Tip Jet Helicopters

[Helidev II]

Let the Games Begin!!!!!

Dividing into 3 catagories;
1, cold cycle pressure driven, where compressed air is expelled from the tips of the blades

2, hot cycle, gas from a turbine exhaust expelled from the tip

3, tip burning, where either compressed air is piped to the tips, and mixed with fuel to provide the propulsion, or rockets like hydrogen peroxide, or self contained motors like ram jets or pusle jets, or even mini turbines.

Im pretty much ruling out No 2. I dont really want to use a turbine, they are expensive, plus the ducting of the hot exhaust gasses seems like a pain in the butt. Even though the X-50 has gone this route, I think that the expense of the heat tollerant materials, the cost of the turbine, will all add up to put it out of reach for most builders.

As far as Hydrogen peroxide goes, Im not a big fan of carrying 2 fuels on board, plus the endurance seems to be very limited.
Ram jets, pluse jets and mini turbines, all suffer from the same disadvantage in the extra drag caused by having the motor out on the tips, instead of in the nice streamlined fuse.

Which really leaves 2 options. either cold cycle or tip burning. Both have had their relative successes, however the cold cycle is the only one to have gone into production, with the Sud Djinn. However the Fairey Rotordyne and the XV-1 both had successful test programs.
One of the disadvantages of tip burning is they suck fuel like pigs. The XV-1 could only hover for about 1 hour, before running dry, not sure on the rotordyne, havent been able to find any figures.
Cold cycle requires more air, at pressure to work, with a sufficient compressor they can work, finding the compressor is the trick.

Tip Jets always seem to have 2 problems to overcome. 1, the relative inefficiency compared with a trans driven helo. 2, Once you get rid of the tail rotor, how do you achieve yaw control.
Dealing with No 1 first. Recently Ive been looking over the old tip jet designs, and comapring them with the only modern tip jet, the X-50. One of the most striking differences between them is the nozzles. Typically the nozzles on the early tip jet designs seem to be quite small, relying on high velocity, lower pressure air. The X-50 has much larger nozzles, and Im guessing a lower velocity. The reason Im guessing about the lower velocity is because funnily enough, Boeing and DARPA dont like to share info on their research projects. :)
Most of us would be familiar with the principal that its more efficient to move a large mass of air slowly, than move a small amount of air quickly. Following this on, it should also be quiter.
One of the problems with this theory is the tips of a helo blade are moving fairly quickly. This means that the efflux velocity must be atleast equal to this speed to maintain RRPM.
2 possible solutions, 1 reduce the RRPM, this would have benefits in terms of noise and vibration. 2 move the tip jets inboard. This would mean the jets are located in a thicker part of the blade, reducing the profile drag, and by placing the jets inboard of the tip, the required velocity of the jet goes down, however this comes at the cost of a higher required power for the jets due to the reduced leverage.

2, The NOTAR problem. Interestingly one of the percieved failures of the XV-1, was the requirement of two small tailrotors to ba added for yaw control in low speed and hover flight.
This seems to me to be a relatively monor concern. Utilising the method employed by the Fairey Rotordyne, 2 pitch controled props, each side of the fuse. Differential thrust enables good yaw control.

I think thats enough for now, feel free to comment, critisize or suggest, see where we end up.

[birdy]

Forgive me if this a stupid idea Heli,but it's been in me head since I started fly'n gyros.[and is a little off topic.]If you shoot it down in flames then I can forget about it and not loose sleep over it anymore.

A jump start[vto]gyro has one major problem if the rotors are mechanicaly driven,torque.
I thought,if you had a prerotor powerful enough to lift off,could the torque be countered with a BIG rudder,with two hinges.One controle would activate a 45 degree hinge to deflect rotor and prop thrust to counter torque and the other for yaw control in autorotation S/L.
Obviosly it wouldn't be a true vto coz the prop thrust would have you moveing forward befor you broke ground,but it would be a STOAL at least.With the stick back on the stoper,the rotor thrust would assist the ground breaks to minamise ground roll.

Is this feasable or am I talk'n out me a.. again.??

[Victor Duarte]

hi christian, i m glad you created this thread, i said in other i am very interested about tip jets.

for me (for a light or ultralight) the best way is cold air... the more the air is cold the more it is "heavy" .

the venturi effect is less pressure, more speed, less speed, more pressure (like traffic jams in sydney or paris ;) )

if you want a good output speed (more than 600 km/h at least, for slow rotors to 900km/h) you need speed AND pressure to output enough air...

i agree improvements are possible on the nozzles to master a good flow.

the yaw IS another problem, in forward flight, rudders do the job, in hover they dont, i thought in use the engine exhaust gases for yaw control, but really unsufficient, in the djinn as in the lockheed model 120 the turbines exhausts blow on rudders, a few persons i talked with told me it is quite a "must be".

you reached the MAIN problem : air production.
the chalenge of the day is : produce enough air with cheap and light devices...
i was thinking in using a piston engin coupled with 1,2 or 3 turbochargers, this solution is employed in the best compressors in the marker, but... sould be too heavy for air production... perhaps someone should overcome this...

for a ultralight, i evaluated the needs of air : at least 2 bars and about 6 m3/second, huge.. must be confirmed by some one else

if you consider to build a commercia VTOl aircraft as i readed your posts, it seems that turbine is really the only way ...

i send again this link :
http://www.technologie-entwicklung.de/Gasturbines/Turbocharger/turbocharger.html

a car turbo could be used as a small turbine... no eng here to fit that?

see lockheed model 120, nice and powerfull bird..

i still thinking something good sould be found.... i wish it will be..

a suivre.... ;)

victor

[quadrirotor]

I expressed many times my position in the previous posts; to sum up:
Tip-jets for an helicopter are noisy and thirsty!... but can be done with success with stock peaces, centrifugal compressor ($5000) belted to a big Subaru etc...(specs can be found for the HELICOP-JET on the site of the CELAG (given previously)...
BUT cold-air-tip-jets could be use for a low powered (15 to 20 hp) offset hinged blades rotor of a jump-take-off gyro with in flight added power (IFAP); using the turbo of the engine...

[Victor Duarte]

hi andre,
what you say looks VERY interesting ! :D
have you further info about a such mounting? i thouth exactly the same way, but with a 503 or 586 , not sufficient on my opinion, so, if you could saiy "yes it works" i d jump to the roof !

thanks andre

victor

[quadrirotor]

the power needed depends on your requirements and your mission profil! all is trade off!!!
The tip-jet helicopter exits and is flying since 1952! 52 years!!! THE DJINN...

[Victor Duarte]

right andre,here, we agree with each other...

so some of expected data

empty weight : about 120 kgs
cruise speed : 130 km/h
payload : at least 50 kgs plus pilot

as i said earlier here, i had the chance to live with a pro pilot who began as mech crew on DJINN and learned to fly on it .. i asked him lots of questions, he s still thinking it is a good helo and regrets that lots of them come out of their lifetime.
this person , Aimé Fabrégat, said to me "there is no "better" pilot, only alive ones", i made this thought mine.

if i can have good info on engines, i have not enough about centrifugal compressors.. have you some?

best regards andre and others

victor

[quadrirotor]

for an helico, you can overcome (to some extents) the inefficiencies of the tip-jets by using a light turbo diesel engine (mecedes smart engine) and the synchropter set-up (only synchronization with homocinetics joints...Dave Jackson's site...no gears.).
For the noise, you can use newly technics of electronic noise suppression (concellation with a sound system by opposing a generated sound to the sources of noise...) experimental. army classified!

[Victor Duarte]

andre

"mercedes smart engine" > yes a german manufacturer is on it ... in my hometown's aeroclub they build a fixed-wings with a 90 hp OPEL TD... i ll go and have a look.

"no gears" > :eek: :eek:

"For the noise, you can use newly technics of electronic noise suppression (concellation with a sound system by opposing a generated sound to the sources of noise...) experimental. army classified!"
> you're right, but classified... not at all ... you may talk about the interior noise, dont know if it could suppress outer one, good blade tips design is actually the best way to avoid "flaps".. the sound system works with compressed air (my brother owns a music studio and some speakers use this device)

i think we can obtain acceptable noise by a better nozzle design or by using elastomeric materials , a kind of noise wall in the nozzle, i dont really know.

did you remark how the night birds are silent... maybe a way to investigate.. ;)

best regards

victor

[quadrirotor]

clic on the pic!
:eek: :eek: :eek: :eek:

[Victor Duarte]

oh ok ok sorry, i m confused, i knew that .. if you have not twin engine, you still need a synchro gearbox , no ? i may misunderstand you.

if a was a malicious guy (for shure i am ;)) i would say that in this part there are much more sources of failure than in gears, am i wrong ? or can we thrust it just like gears ?.

[quadrirotor]

Yes this kind of joints are fragile, but the one used in your car (with balls) are fail-safe as they make a noise a long long time before braking! :o anyway they are not loaded, only synchronization!

for compressor, there is a link:
http://www.vortron.com/products/blowers.html
make a searsh with googles too! ;)

[Victor Duarte]

yeah ! thanks for link .. filed in my database....

for the car joint, i know well by having experimented it by myself, i could hear the noise much before failure, i agree, but when the balls crushed...no way to go further... i changed both bearings myself.

thanks andre

victor

[quadrirotor]

As the synchonization is not loaded, you could use a flex cable as the one used for the wunderlich prerotator!!!! I am joking!!!!

[Victor Duarte]

i m reading about the compressor, still have problems with units conversion :(
looks interesting ...

[PTKay]

Victor, I am dedicated to diesel in aviation, can you report more about the fate of this Opel (GM) engine in the plane. I've seen a lot about it on internet, but everything I saw is more than 2-3 years old.

And most of it is in French, and my French is only slightly better than Chuck's B.
(although I cooperate with a company in Lorient)

Is it the Dieselis ?

http://membres.lycos.fr/dieselis/

Please, go and check if this project is still alive...

PTKay

[Victor Duarte]

i ve converted the units.....well ! i may be wrong but maybe there s a way to succeed.. ;)

for example the z40 model allows quite 8 bars where 4 are enough but only 2.8 m3 /minute where about 10 sould fit :confused: ... i must see before telling more (silly things :p ).

thanks andre

victor

[Victor Duarte]

PAUL >>>>

by now i dont know, i had a fiew pictures in my hand but cant confirm it is dieselis, it may be...
i ll send my sister's boy friend ( he pratcices RC helico) and often crawls by the hangar, they are friends and they try to convert him to full scal flight :D

i ll tell him to take picture and infos, unfortunately and fortunately, i m going to be father and in the last month i cant EVEN have my adored GF out of sight !!!

well.. it may take a fiew days but i will get the info....

victor

[PTKay]

Thanks Victor.

[quadrirotor]

ecofly may be???

[Victor Duarte]

act with others just as you would like them to act with you (or something like that)... dont remenber the name of the engineer but sounds good ;)

[Helidev II]

Andre, you are right, traditionally the tip jets have been fuel and power pigs.
However that doesnt mean that they have to be so. Prior to the X-50 virtually no research had been done on tip jets, while other designs were persued. Look at the tilt rotor, compare the figures of the XV-3, with the V-22 or the XV-15, they are marked. New technologies often present new ways of refining old ideas.
One of the interesting things about the Mcdonnel 120 is it used the blades and head off the XV-1. The difference was in the tip burning, the 120 was purely pressure driven, and I dont know of any other helo that can lift 1.5 times the empty weight.

Victor, we seem to be on the same page with alot of things. One idea which I have been thinking about, but havent really looked into yet, is having a small turbo run by the engine, the compressed air then drives a larger turbo, kinda like a turbine with its different stages. Like I said Im not real sure on it right now, its more a napkin sketch which needs work.

I probably should have been more clear on my design. What Im thinking of is more of a helo/autogyro or a gyrodyne. Looking at helocipters very few opperate in the hover all the time. With the exception of operations like logging or long lining, most helos are VTOL transports. Seeing that gyros have the ability to fly slow anyway the main time you need a hover option is for TO and landing. Keeping this in mind Im prepared to accept some loss of efficiency in the hover. Even if I loose a bit here, Ill be making up for it in the forward flight profile.
Because the aircraft can hover, it will mean I can run a little less blade than for a traditional autogyro, which should help with the forward speed profile.
Another benefit of the tip jet is that what I loose in efficiency I gain in simplicity, and reduced weight.

Birdy, yes your right with your idea. Infact most of the tip jet helos used this idea, however they used deflected exhaust from the turbine . You couls actually still have VTOL with this idea, you could balance the thrust from the prop with aft cyclic to remain stationary. What I propose is to use 2 props off the one engine, with differential pitch on each prop controling the yaw. This has a big advantage in that there is nothing on the helo that isnt doing something useful through all stages of flight.

Ill post more soon.

[Helidev II]

Sorry Birdy I missread your post.
Your Idea would work assuming a couple of things. 1 you had collective control over the blades, and 2 you have enough power to drive both.
The real problem lies in the weight of the trans required to drive the MR.
I would love to tell you it wouldnt work, but in theory it would, whether it would be worth while or not is a different story.

[quadrirotor]

Yes Helidev, there was a concept shown in the HOMEBUILT ROTOCRAFT magazine, the name is the Cyclone, it consists in using the Subaru engine with its gear boxe, which has been lightened of some gears, the rear PTO (on the car) is used to power the trans of the lifting rotor...The two front PTO (used for the front wheels on the car) are used to power two side propellers...why not?

[birdy]

Thanx Heli,I wasn't expect'n anything positive like that.
Andre,I reckon the weight would be git'n prohibitive with a soob AND gearbox.

I know the fixed gyro rotor pitch wouldn't allow for a real vto coz you'd loose ground break effect befor you got close to lift off,but it'd still make for a very short TO roll,no??Full backstick and a little wind I reckon would allow for a VTO.
Surly they could make a hydrolic preroter that could produce the rpm.
The systm I'v been think'n of would only need the different rudder,beefed up head,mast and tail boom to take the extra loads and it would be near VTO without the complexity and weight needed for real VTO.
The yaw your both refering to ,is that wot I was call'n torque.??
The 45 degree rudder would counter that,no??
The trans driving the MR is only for liftoff,then covert to conventional gyro as AS increases.

[quadrirotor]

heavy compared to what?

[Victor Duarte]

hi andre , christian and everyone !

christian and andre i posted on "coax" but re-post it here..

look at that : www.rotrex.eu.com/

sounds like we have a solution for a small tip jet.. or may approch one...
christian it should rise a great interest for you.. ;)

i posted some questions to dave jackson on eng-tips hope i ll have some answers...

just throwing some more to the wall , christian ;) :D

friendly

victor

[Helidev II]

Yeh I replied in coax, Ill try to post more tonight.

Birdy, what your describing is similar to jump takeoff. If you made your blade pitch adjustable, abd the head able to take about 150%RRPM then you could use a powerful prerotor to spin the blades upto about 150% of operating RRPM, then pull pitch and up you go. Because you wouldnt be applying torque to the airframe by driving the rotor in the air you wouldnt need to modify the rudder. I beleive the Carter Copter uses this method for a VTOL take off.
I beleive theres a bit of timing involved to get it into the air, because you will have to build speed fairly quickly as you are airborne well on the wrong side of the power curve.
Yeh the yaw is caused by the torque.

[birdy]

I understand wot your saying bout the rotor pitch Heli,but it's the commplexity of that systm that I'm trying to avoid.
The way I'm look'n at it is to keep it simple.You may need a bit more power than a regular gyro,but because you would be very light on the ground[almost off] when the machine starts to accelerate[but still prerotating],there would be less chance of git'n caught behind the curve.And probably more idiot proof than the more sudden mode switch in something like a Carter C.
BTW,could the rudder have enough effect to counter torque.???

[Victor Duarte]

hi christian , andre and ohers

christian and andre > i cant log to eng-tips , and all the posts seem to be those of more than a week ago.. have you the same problem?

[quadrirotor]

yes i do!...

[PeroxidePropuls]

As stated in the discussion the yield improves if having a lower gas velocity out from the nozzle.The maximum yield is when the gas velocity is 2 times the rotor tip speed.
The problem is a lower velocity needs to be compensated with a higher mass flow, because the thrust is the mass flow times the velocity -But if the mass flow comes from the fuel or a compressor, one end up with a worse economy. The only way to come out of this is to have an air breathing engine, like a jet engine, that takes the extra mass flow from the surrounding air at the rotor tip.

I have made one attempt to make a very simple jet engine without any moving parts. I call it the ejector jet. You can read about it on my web site: http://www.peroxidepropulsion.com/article/17
It did not work so well at the first test though, -but maybe it can be improved...Anyone have any ideas?

Another simple jet engine with peroxide propulsion would be to make a da Laval turbine, with fan blades at "b" in the drawing. I believe this jet engine would be easy to build and to balance and there is no direct contact/no sealing between the nozzles and the rotating fan.

These solutions may be good for a helicopter, but for a gyro I still believe, anything bigger than a tiny rocket with aerodynamic profile will course too much drag and disturb the auto-rotation.

[Victor Duarte]

cancelled ...

[PeroxidePropuls]

Victor,
My idea is one should use peroxide tip rockets for making VTO or jump take offs with gyroplanes, because the fuel economy does not allow for continious operation as on a helicopter. The rockets can also be used at tricky flight situations and at landings of gyroplanes, I believe (not yet tested). This would make the gyro almost as useful as a helicopter, I belive, at the same time as all the benefits of the gyro technology is kept, -like low cost and easier to learn to fly.

The total weight of my prototype system is 13 lbs. It can be squeezed in below the holy 254 lbs for an UL gyro, like a Gyrobee or a Butterfly, if using Dragon Wings (the tip weights can be removed when the rockets are installed at the tips) and using a Rotax 447, 40 HP. The volume of the gasoline tank plus the peroxide tank must be maximum 5 gallons together, according the UL codes.

You find more about this if you take a look on a thread under "Engines" in this forum.

What I tried to say before is that IF using peroxide propulsion tip jets on a helicopter, the fuel economy has to be improved, in my opinion. I suggested it could maybe be done by making a high rpm "microturbine", based on a de Laval turbine. On such a turbine, the exit gas flow from the nozzles acts on the vanes at the outer perefery of a wheel. On the same wheel, -inside of the vanes, one could put fan blades, that pumps the air through. The nozzles could be mounted on a duct, outside the wheel. The duct is clamped to the rotor tip. The gas to the nozzles comes from a peroxide gas generator -also mounted on the duct.I cant explain my idea any better than this without making a scetch. I will publish a scetch when I have some time over if there is an interest in my crazy ideas.

[Victor Duarte]

cancelled ...

[PeroxidePropuls]

Well Victor,
The surrounding duct can be made with an aerodynamic smooth form, so the microturbine would pritty much look like a normal jet engine. Than the drag will not be a problem, I think -as long as we are talking helicopters with the engine in operation all the time.
When the air inlet is turned towards the speed wind, like I would like, the thrust will be maintained at high rotor tip speed. If you turn it horizontally, like you have suggested, the thrust will decrease at high tip speed, I think, because the relative velocity will be lower when the engines own velocity can not be utilized equally efficient for pushing the air through the fan.

[Helidev II]

Birdy, collective pitch wouldnt be that hard to add. Ive seen somewhere here an example of a really simple collective head. It would really only need two settings, one for spool up on the ground and one for flight. You have to remember that any extra system adds complexity whether you want it or not.
I have doubts that with standard autorotative pitch the rotor would be able generate enough lift for a vertical takeoff. However there are others on this site with far more knowledge than me on Jump take off gyros.
With regard to the prop having enough power to overcome torque, probably. It will depend on the drag of the blades and the efficiency of the prop. Where you will more than likely strike trouble is the amount of power required to run both. Your trying to gain airspeed, in the highest power required part of the zone, while trying to power the rotor as well. Especially considering the DA you run at up there, I would think youll run short.
Give me your rotor diameter, blade section, blade chord, and engine hp, Ill do some calcs when I get a chance, let you know how much power you would need to get in the air. (Average temp and alt above sea level would be good too).

Victor, for some reason someone has decided that one of your posts was inappropriate. This happened to me a while ago. You can email the moderator of the group to get let back on. It ticks me off when they do this, but its such a great resource that you have to put up with their rules. Unfortunately half of a great discussion is lost.

Erik, thanx for your thoughts. I must confess I do like the idea of the Peroxide jets, however I think that 2 kinds of fuel is a little limiting, especially if you are planning to use the vehicle in “heli” mode.

It is funny though. The other day at work I was thinking about the tip jet efficiency problem, started thinking about the turbofan over a traditional jet, then thought what if I added a venturi tube around a high pressure air flow, it should impart extra energy to the flow. Made a little note for future investigation. Then I get home, and read its called an ejector jet.

With regard to the efficiency of the tip jet, as far as a pure helo, it may not be very viable, unless the reduced weight/complexity offsets this enough to be of benefit.
However where I believe it can be of great benefit is in the area of the compound helicopter.
This is where the reduced weight/complexity really pays off. For the same gross weight, a compound helicopter will not match the range or performance of a conventional helo. However by getting rid of the trans, and associated bits and pieces, you can have a compound helo which MAY outperform a conventional in most areas, especially as a transport.
I really want to stay away from combustion tip jets if possible, the noise may kill the project before it starts. Im wading through a report on the XV-1 and the noise was around 100db @ half a mile!!!!!!!
Typically the idea of using a turbo fan was to mount it at the tip, however what if you mounted it near the blade root, normal to the chord? You get around the centrifugal forces being a factor on the turbine.

As stated in the discussion the yield improves if having a lower gas velocity out from the nozzle.The maximum yield is when the gas velocity is 2 times the rotor tip speed.
The problem is a lower velocity needs to be compensated with a higher mass flow, because the thrust is the mass flow times the velocity -But if the mass flow comes from the fuel or a compressor, one end up with a worse economy. The only way to come out of this is to have an air breathing engine, like a jet engine, that takes the extra mass flow from the surrounding air at the rotor tip.

Erik is this from your experiments/calculations, or have you found some info on this?
While the need for greater massflow is an important consideration, by reducing the velocity you can reduce the noise.
Im curious as to your thoughts on moving the jets inboard to say 75% R, while you would need to apply more force, it would allow for a lower exhaust velocity again?

[birdy]

Heli,wot is used to counter torque with the 'simple head' setup your talk'n bout??
I'm not try'n to VTO,just shorten the roll.
If you could git to 100% rrpm with the prerotor,then your going to have a short TO,but you'll need some way to counter torque coz your going to be very light on the ground.


Blades are 26' extruded alu,don't know the section,I think 7" chord and 60hp concervitavly.Av temps bout 25c/30c[range,-11 to 48] at 2000'.

[PeroxidePropuls]

Hi Birdy and Christian,
I am not sure I understand your discussion about vertical take off and stability, but for sure it is possible to make a vertical take off with a gyroplane when using my prototype tip rockets.
Take a look at the movie called "VTO1" here: http://www.peroxidepropulsion.com/article/23 Is this proof or not? The take off was stable and controlled when the rotor disc was slightly back, so the gyro wanted to go up and back. At the same time one need thrust from the propeller that want to push the gyro forward, in the same way as the stretched towe rope in the mivie file.
The file "VTO2" shows that the VTO can also be unstable if lacking the balancing forward push from a propeller.

Torque force that want to twist the gyro is not a problem.

You can see the successful transfer from VTO to forward auto-rotation gyro flight, if you look on the movie files here: http://www.peroxidepropulsion.com/article/24

I hope I have not missunderstood what you are talking about.

To Christian regarding gas velocity: I found the "times 2 factor" in an old article by Dr. de Laval, where he discribes how the de Laval turbine was developed and optimized. I have assumed the rule is a general rule, valid also for tip rockets an a gyroplane rotor

[Victor Duarte]

christian,
"for some reason someone has decided that one of your posts was inappropriate." ,... whitch one?

i didnt see that.. have you an idea why? i hope i didnt do wrong with someone, if so, i apologize. :o .. hope its not because of my bad french-english ... someone just tell me if i break a rule.. i ll be aware... thanks

thanks

victor

[quadrirotor]

Helicopt-jet: 2.15 kg air /seconde at a pressure ratio of 3.5:1...four blades/9.40m...
230 kg of fuel for 450 km at gross 1060 kg, 4 seats... almost 800km with fuel instead of 2 passengers!... witnesses said it was a bit underpowered at gross!...

[Victor Duarte]

many thanks andré!

here we are, the needs of air are HUGE and the fuel needed also.... not mentioning the noise...
if i divide /4 the mass, im not shure the air can be divided /4 also .. i m not shure the features are linear..
by the way the compressors i ve seen (sorry andre , dont remember the Vortron ones but they are quite comparable) the 3/4 of max air flow is about 0.2 kg/sec and the exploitable pressure ratio about 2:1 .... seems to me that even for an ultralight, the compressor (s) should be HUGE...

what is your opinion .... do you think its definitely and idea to drop?
no one talks about noise reduction...

[Victor Duarte]

Erik i saw your videos.. really impressive... looks very fast at start!
on your site we can see you handle the peroxyde tank... is this really as "easy" as that ?(i guess it is not) .

didnt you experiment problems with ducting the peroxyde through the rotor ? no losses?

i have very "naive" questions but... what is the autonomy (estimated) of consumption, what is the price of peroxyde, handling and stok conditions?

thanks

victor

[quadrirotor]

Victor, to go to a tip-jet helico, as i said many times before, you'll need a lot of power, and too noisy! and the type of compressor needed could be different from the one i showed you. May be you have to go with the type below!...
But for prerotation and IFAP, VORTRON is enough; even, may be the turbo (exhaust gaz powered) of the main engine could be!!!!

[Victor Duarte]

andre i think you re right,
dont have info about screw compressors, i ll check them..
as i read posts... i havent heard about significant improvements possible for cold tip jets that should make me think it s a good way... for the moment, i m fishing informations.... before going for coax, jt or syncho, or gyro, i prefer to talk with a lot of people to make my own mind, then i classify them in "those who work" "those who could work but" "those who do not work"

some one posted a thread (Ptkay i think) about a dream machine, mine could actually be a kamov KA 56 foldable coax .... not far from a gyro at all.

in fact... all i need is a gyro !! ;)

thanks for the help andré !

[birdy]

Erik.
I'm drooling at the sight of those rotors spinning up so fast,it looks good.
But from a practicality point of view,where am I going to git HP out here.How long dose 5 liters last?
Could it be a fire hazard?
I know nothing bout HP.

[PeroxidePropuls]

Hi Birdy,
Do you need to make VTO on the grate plains of Australia?
I think after some training one can make a zero ground roll take off with about a liter of HP = 15 to 20 seconds run time of the rockets.
Peroxide does not burn itself, but if you have a spillage on textiles or dry grass, it can start glowing and take fire after a while -unless you have some water available to pore on it (Water is maybe not available were you have your farm? -but some beer is also probably making the job)

Supply is a big problem. The main producers avoid any other market sectors than the military and the space industries. You have one producer in Australia. It is Solvay-Interox. You can contact and ask for a price, but dont have too high expectations. I plan to make a shipment to US, to have at least one single depot there to start with. I am afraid it will take time for me to estiblish any desent kind of distribution net, that covers Australia.

[birdy]

You better belive it Erik,Theres places here where I'v got less than 150m to break ground.And on a 45c day and no wind,a powerfull prerotor would help no end.

Roughly how much $$ for a liter of HP??

[PeroxidePropuls]

I need US$25/gallon = US$ 7/liter as long as I have the small production I have now. When the stuff is arriving to you it may very well cost you almost the doubble because of the transport (hazmat transports). I am afraid Solvay-Interox will not offer you any better price.

[birdy]

I thought as much.
May as well be pump'n liquid gold through it ay.
Never mind,I'll just keep drem'n.

[Victor Duarte]

cancelled ...

[PeroxidePropuls]

Zeeoo,
Dont mix up Hydrogen and Hydrogen Peroxide. Hydrogen is gas that explodes in a mix with air. Hydrogen Peroxide is a liquid.

[Victor Duarte]

ok ok erik,sorry, i didnt mean to upset you, i know the difference, just trying to tell my interest in your work... i m not enough skilled to have a debate about that, thanks

[Shadow]

[QUOTE=. . . . . The tip-jet helicopter exits and is flying since 1952! 52 years!!! THE DJINN...[/QUOTE]
Correction McDonald had a rotor tip Ram jet Helicopter in about 1948. I had pictures of it and the Banshee Jet that McDonald was making at the same time.

[Victor Duarte]

andre, i recieved some documentation from Hutchinson-paulstra about elastomeric products and active noise elimination ones, if you re interested, i can scan them.

[quadrirotor]

Zeeoo, can you do an executive resume, If You please, not to scan too many?
what the principle, where do you apply this product, etc???...

[Victor Duarte]

ok i try a quick overview :

cabin noise attenuation > they use an accelerometer on engines to catch vibes, microphones in cabin to catch ambient noise spectrum, then, sent to a calculator , then transmitted to a power amplifier that controls actuators one the engine, didnt see any use of acoustic devices..;

use of elastomeric in noise reduction > on airframe skins , an elastomeric layer is put between constraint skin (outer composite skin) and base layer (inner), the elastomeric absorbs and damps the distorsions on outer skin due to turbulences and vibes and then attenuates their transmission to the inner volume...

in fact it s a little more complex, but i got only a global doc..

i m still looking for high speed air noise studies, found one about the measuring of vorticity on a supersonic air jet, but no clue to reduction..
i still have some ideas but do not post them here, i could appear as a mad thinker and will be considered as unappropriate, regarding my aero-engineering skills whitch are close to zero.

[quadrirotor]

This is important but that's not what i am looking for: obtimisation of the tip thrust nozzle. What shape must have this nozzle to be:
1-efficient.
2-the less noisy as possible.

May be i must look at the rocket industry?.
thanks Victor.

[Helidev II]

Erik, my appologies, I misread your post, with regard to what you were trying to achieve. Unfortuantely being in a different time zone gives me a lot to reply to in one sitting.
I agree that for a VTO gyro your soulution is both simple and elegant. The only problem is getting the fuel, which as you say can be self distilled.
If I may add a couple of thoughts. It appears in the video that you are using RRPM to control the rotor thrust. If this is the case, you may want to consider a collective control instead. Alothough it does add mechanical complexity, it is a more presice method of control, particularly in the hover. One thing that you find with a variable RRPM is the lag involved, and while a person can get used to just about anything, you may find that a collective control reduces the work load immensely. Another bonus would be the fule saving. For example right now your running up the rotor with some AoA on the blades, which provide enough thrust to lift the craft at a given RRPM. However if you un the blades up at zero pitch, there would be less drag to overcome, meaning less fuel would be required to achieve operating RRPM, or conversely a quicker run up time.
To control the power of the tip jet, you could use a corelator so that when more collective is applied more fuel flows to the jet, maintaining RRPM.
I’m really interested in the ejector jet idea, but using compressesed air instead of a rocket. While you wouldn’t get the thermodynamic benefit, you may be able to increase the mass flow of the system, by taking advantage of the higher dynamic pressure at the blade tip.
However the lack of thermodynamic change may be a show stopper for this idea, as the extra energy imparted to the flow by the thermodynamic expansion of the air in the nozzle may be a large source of the extra energy?

Tip burning is one thing I would like to avoid, assuming I can get around it.

Birdy, on an completely unrelated topic have you considered going to a 44 instead of a 22. For about 200k Aus, you can pick up an astro which wont have the lack of power problem the 22s have. Another option would be an older MD500, with a C-18 in it. These are a turbine, but have the benefit of not being cycle limited like a C-20, meaning your not as limited in start up/shut down.

Victor, I don’t know which post they felt was inappropriate. Like I said earlier they can be pretty funny about things there. I posted my email because theres no PM service on there, and they decided to remove it because of the possibility of spam email. Go figure.

Andre, whats the gas production method employed for the Celag? Is it bleed air from the turbine, or ducted exhaust?

There are 2 main things that I think need to be overcome
1, noise
2, power

Ive put noise first because in these noise sensitive times, even if you have the power, if its to loud you wont be able to fly anywhere, plus it scares the cows.
I think that the shape of the nozzle could be a good place to start. I was watching a show the other night which showed a 40% reduction in the heat eliminated by a turbojet purely by the nozzle shape. Interestingly it was noticeably quieter also, although being on TV that could have been mike placement.
Andre with regard to looking at rocket desing s for noise suppression I think it’s a non starter. To my knowledge there hasn’t been one study into making them quiter, that I know of. Purely because they don’t need to make them quiet now. They need the power and that’s all they car about.
One reason I don’t like the tip burining as much is because it nesseccitates a high exhaust velocity. This is always going to be noisy. I think the main way to get it be quiet will be through use of nozzle shape and reducing the exhaust velocity, how to achieve this Im not entirely sure yet, however you have to start somewhere.

Power, the power required is mainly a function of the disk loading. Keeping this in mind for a given gross weight and disk area, the power required is then only varied by the efficiency of the rotor, and the method of getting power to the rotor. This is where a transmition driven rotor has the advantage.
One interesting comparison though is that between the Bell 47G, and the Sud Djinn. Both are of a similar time period, and utilise similar construction. Both use symmetrical aerofoils, of 10.7m diameter.
The Sud has an empty weight of 360kg, and a max gross of 800kg, while the 47G had an empty weight of 651kg and a max gross of 1067kg.
I couldn’t find the exact figures for the 47’s hp, but off memory its about 150, while the Sud has about 236hp.
What becomes apparent from these figures is the 47 has the greater gross weight, with a lower payload, however this could just as easily be due to the difference in weight between the piston and turbine powerplants.

So I guess without an improvement in the areas of noise and efficiency prospects aren’t so good.
Id love to know what the Mcdonnell engineers did to get that performance out of the 120.

BTW, the first tip jet was built in germany during the second world war.

[birdy]

With the greatest respect to you and every helicopter bloke Heli,I'd never use a chopper.
The gyro just can't be beet for efficiancy,simplicity[like me] and convenience,not even thinking of cost.
From a muster'n perspective,the only advantage the chopper has is the ability to have a fuel dump anywere.The hovering thing with mustering is way overrated.If you need to hover coz the critter has bailed up,then hover'n wont move it ether.I'v been able to do wot helie pilots do with cattle in a machine thats mechanicaly simpler than a bike.
If your go'n to use a vto gyro for mustering,then it'd need to be able to hover as well,otherwisae theres no real benifit gained over a basic gyro for the added complexity.
If I could make a very short TO gyro,then it'll do.

[Victor Duarte]

hi christian and andré ! well i try to push the subject a little more....

chris > the b47 has lycoming about 150 hp, depends on the make, the DJinn has a turbomeca "palouste" whitch was specially fitted to be coupled with a turbocompressor.. CELAG is a museum, a enthusiasts club in grenoble, not really a tests-center, i know its pretty hard to find real docs about djinn..

i kewn a person who knows it very well : my ex-GF's father , as you imagine i didnt keep links for personnal reasons, but he s a nice person, if you feel you can phone him, the name of his helico company is "touraine hélicoptères" at "NEUVY LE ROI"... was for info only.
but i think the best way to have docs is on sales bids, you can ask the vendor to fax you tech data, tbo manual etc....

about the power > i havnt dropped the idea of cold air pressure tip jets, but i m not shure we can evaluate it like in a classical one, the rotor load is not the only factor..

the first thing we should evaluate is the air needed... two procedures could be done :
1 > with a heavy duty compressor, make a dummy blade, put a nozzle at the tip, measure pressure, air speed and the torque generated, this measures should be done with several diameters of nozzles, of ducting tubes and several presure/air mass settings..
( i saw a video where a japanese team made an helico fly with a ground compressor)

2 > test several turbochargers or superchargers (andre suggest screw instead of centrifugal ones), by coupling them to a piston engine, dont mind the model, just to evaluate the air production.. at whitch HP , RPM etc ... even an old used engine could fit.

these two small tests done we could know if the air production is suitable for this purpose.

alas, as i said in one post, i m going to be father soon and cant move to a place i could work on this, probably next year..

for the noise, i still thinking theres a way to reduce it, the noise seems tobe generated by th air vorticity at supersonic speeds, creating continuous shockwaves (like a jet aircraft) ...

maybe we should investigate in 2 ways :
1 > to "quiet" this air at the exhaust until it expands... remember i talked about the nightbirds and the way their quills "silent" their flight... have alook at water algae in a water stream... between their leaves there is quite no turbulence.... as they fit the stream lines.... may be a clue ? or im really mad

2 > absorb the noise before exhaust ... a gun silencer absorbs the "bang" before exhaust ... i really dont know if applicable here, just trying to find a clue.. what we know is that sound doesnt propagate in empty air (or V low densities).

3 > different kind of nozzles ... dont know much about whitch type, just know that there are new improvements in firefighting stuff nozzles... for example i know they mix a substance to the water to make it slide better in the tubes ( a kind of fish mucus )

nature invents, the man reproduces...

just passing... friendly ;)

[PeroxidePropuls]

I have been offered to buy a UL Kestrel tip jet helicopter. I can get it to a good price, because the guy owning it cant get it up in the air, because the Gluhareff propane driven tip jets are too powerless. I am quite convinced my HP tip rockets would make it fly. The Kestrell helicopter has collectiv pitch controll, so it would be possible to hoover with it, I guess.
The problem is the fuel consumption. I think it would need at least half a gallon of HP per minute. The UL code allow for a maximum 5 gallon tank. That would be 10 minutes of operation. That short time of operation would make it a toy, -not a useful aircraft. Could one install a pusher propeller on it? Would this make it a gyroplane with collective pitch controll? I dont think so myself, but it would be interesting if someone with more knowledge and understanding than myself could comment.
Does anyone have any experience from the Kestrell helicopter or from the Gluhareff tip jets? -Both are sold as kits or fully assambled by Vortech.

[quadrirotor]

Victor, all has been done! see the V.F.W. the coumpound helico H2:

http://www.vstol.org/GermanVSTOLRotorcraft.pdf

[Victor Duarte]

thanks andre ! i have seen that but didnt have it in PDF, thanks,
yes i agree all has been done except Anti-G (may the gravitationnal forces be with you ! in a far far galaxy.... etc) .

yes my interest is EXACTLY in the H2, if it has been done, its better, i dont try to reinvent the wheel, just to use better tyres ;)

in your posts andre , i can clearly read that you think the compound is the best way..
what do you really think, sincerely.. i see the direction you are looking to, but you still very careful in comenting my thoughts... do you think i m mad?

best regards

victor

[Rotor Rooter]

An interesting and semi-technical report that was produced last year. The Convertiplane had a jet tip driven rotor.

An Overview of Autogyros and The McDonnell XV-1 Convertiplane
http://rotorcraft.arc.nasa.gov/publications/files/NASA-CR-2003-212799.pdf

[Victor Duarte]

RotorRooter i cant downlod this publication :( i found it on the web, no way !.
classified ? ;) ... have you a hard copy ?

also have a usefull link, some interesting docs, didnt read them

http://rotorcraft.arc.nasa.gov/publications/pub.html

[Helidev II]

Some of this follows on from what was posted recently in the Dream Machine thread.
That paper on the XV-1 is really good. Ive only had the chance to read through it once, but the info is great particularly with regards to the different requirements for convertiplane MR design.

With respect ot the noise issue, I recently found a section on tip driven rotors in Ray Prouty's Helicopter Aerodynamics. Interestingly it puts the noise of the Mcdonnell XV-1 @ 110db @200ft (doesnt say speed, alt or distance) with the Rotordyne @ 120db @ 600ft, which is pretty bloody noisy. Especially considering its a logarithmic scale. I have heard they got the noise down to 96db, but I dont know at what range.
Ray Prouty also states that the Djinn was quieter, although without figures, and the hot cycle XV-9 quieter agian, again without figures.
The efficiency of the Djinn and the XV-9 is also stated to be better than that of the XV-1 or rotordyne, but without figures to compare.

I think that any form of tip combustion is going to be loud unless there is some way of either muffling the exhaust, or starting the combustion earlier in the process, like in the mast or blade root.
I think that 100db @100ft would be a good goal for a 2 seater 15000-2000lbs gross weight helo. I have measured the sound of a 22, 44, and an EC-120. The 22 and 44 both ran 100-102db, while the EC-120 was whisper quiet @ 86db. This is more than likely due to the difference between a tail rotor and a fenestron.

Whether the tip jet is the best option for a pure helo is debatable. While there are obvious weight savings, and reduced parts count, which would go to reduced costs, the losses in the system may kill these benefits.
I beleive that the tip jet is the ultimate though for compund rotorcraft, where the lack of trans and associated parts reduces the weight enough to counter the added weight of the props/wings.

Perhaps we are looking at the problem from the wrong end though.
For exapmle the MD Notar system uses the canoa effect on its NOTAR helocopters. Using a variable pitch fan to supply low pressure air in large amounts supplemented by an adjustable nozzel in the tail.
Assuming we used this as a model, what if instead of using a compressor, we used a small variable pitch fan?
OK it adds to the parts count, (although you could do away with the compressor), however it does solve the problem of mass flow.
You could use an acsessory drive, at 1:1, as the required power would probably only be in the order of 80HP or so. (Wild guess based on no facts)
Thoughts?

[quadrirotor]

The doc of Rotor Rooter is really good. Definitively, the noise is the problem. Without serious R&D about the nozzle noise and efficiency, this system must be used on low powered system for added power.
For a user friendly helico (NASA requirements...), it's not 100 dba/100ft which is the aim but 85dba/100ft, and less...so no tail rotor (no noisy prop...), multibladed rotor with special tips, engine soundproofing, etc... The simplified synchropter is a good candidate...unless the no-torque torque converter is a reality...

[Victor Duarte]

i suspect the presence of dave jackson somewhere by here... :cool:

[quadrirotor]

Who is Dave Jackson?

[Victor Duarte]

finally i got the doc of Rooter's post.. its huge

interesting INDEED, particularly the design of the rotor.... i know now im not on the wrong way, but when i saw the control system...wow.. not simple..

i still reading it..

[quadrirotor]

I had pb to send you this doc too big!

[Victor Duarte]

ask doc to Kestrel, interesting to have, but not detailed ;(

Simon Scott
Managing Director
Kestrel Aerospace Ltd
United Kingdom

Tel: +44 (0)1782 644409
Cell: +44 (0)7981 120045

WWW: www.kestrelaerospace.com
Email: sscott@kestrelaerospace.com

[quadrirotor]

What have you seen interesting?

[Victor Duarte]

just a cross section of props..nothing more.. i sent you the docs by mail .. check your hotmail

they just use a second stage to counter torque and create 2 indentendent flows... i think they re not so independant.. i would have more info about size, thrust etc

[quadrirotor]

Thanks Zeeoo, nothing more than on the site.

[Victor Duarte]

andre you should mail Simon from Kestrel for info, he takes the time to reply, whitch is pretty rare from others, i appreciate.. thanks to him

[quadrirotor]

I don't see redundancies in their project! ;)

[Victor Duarte]

well, i worked for a guy "Jean Claude Andruet" a (80's) world famous car races world champion, he was in golf business and was building a 4x4 electric caddie for golf and other uses.. i was working on marketing strategy .. he uses an electric high torque motor in each wheel.. he could climb 45 degrees lawns (i v seen it by my eyes) .. i think electric motors is also a way to investigate.. is the production of electricity onboard more efficient? dont know ... i m ignorant, i just feel that adding losses in piston engine plus losses in electrical motors just may create more losses... whats about reliability ?

the solution is perhaps in fuel cells .. and the pioneers will be tomorrow's winners.. if they hold on.. a thing is shure.. some day we wil have to leave our wings or rotors to fly something different or new...

[quadrirotor]

The noise will be the discriminent! :)
fail-safe, redundancies...

[Victor Duarte]

yes for civilian aircafts... i see the aero industry bust begins to build-in antinoise systems... its clear electric motors are silent... the air is not ;) .. i stil investigate, you know, when ill go to my parents ahouse, ill just try a heavyduty compressor, of mount a turbo i have on a small engine... and i ll test several nozzles... i have some ideas... i have also sound stuff for measures... my brother owns a studio and is also involved in noise suppression inn any kind of building (night clubs foor example) . we have a lot of materials to tes (skins, foams etc) .. i l learn a lot

[PTKay]

I just found a "gold mine" of pics and links on tip jets.

http://www.flightforum.ch/forum/showthread.php?t=27290

It's unfortunately in German, but have patience and just
go through all the pics and links.

For me - a great site....

PTKay

[Victor Duarte]

oh oh thankyou paul!
unfortunately i dont speak german, but the pictire i saw are pretty interesting...
thanks

[quadrirotor]

Thanks Paul. :)

[PTKay]

You are welcome...

Yes, Switzerland is THE helicopter country. Enough cash and flying FW there
is really no fun...

I worked there many years ago (as a student) and have seen glider pilots
doing most impossible things in those narrow Alpine valleys.

I will try to help you (with my German knowledge) to find some more
interesting things there.

PTKay

[Neil C.]

I expressed many times my position in the previous posts; to sum up:
Tip-jets for an helicopter are noisy and thirsty!... but can be done with success with stock peaces, centrifugal compressor ($5000) belted to a big Subaru etc...(specs can be found for the HELICOP-JET on the site of the CELAG (given previously)...
BUT cold-air-tip-jets could be use for a low powered (15 to 20 hp) offset hinged blades rotor of a jump-take-off gyro with in flight added power (IFAP); using the turbo of the engine...
Do you think the Wright brothers were concerned about economy when they were experimenting? How thirsty is the V-22 ? (I heard Mr. Keller say these words when asked a similar question concerning his Pressure-Jet design)

[quadrirotor]

There are not many people flying with the first airplane neither!

[Neil C.]

If the nozzle orifice were (all 10 of them in Kellers design) close to the bladetip, wouldnt some tiplets help roll off the building sound/shock wave ?

[Neil C.]

An interesting and semi-technical report that was produced last year. The Convertiplane had a jet tip driven rotor.

An Overview of Autogyros and The McDonnell XV-1 Convertiplane
http://rotorcraft.arc.nasa.gov/publications/files/NASA-CR-2003-212799.pdf
Asymetrical Lift and all the weight from redundant shafting will be the demise of the v-22 -according to Keller.

[Neil C.]

I see the thread of discussion on tip-driven technology has been going on for a year at least and I feel fortunate to have found it. I was never interested in tip-jet rotor designs until only a couple of years ago. On behalf of my retired helicopter engineer friend, who is non-computer/internet savvy, Mr. Merrill Keller I would like to direct all who are interested in other tip-driven applications/methods to his temporary website which is...

http://www.lowdollerhosting.com/keller/index.htm
The beauty of Mr. Kellers design seems to be not only the short span rotor blades, but the frisbee shaped center plenum which acts as a lifting body during forward flight, unloading the blades for faster forward airspeed and stability. A canard would assist in yaw control. Aft dump of warm cycle exhaust would assist in steering.
On Mr. Kellers website you will find his home telephone number and he has told me that he will take calls from serious inquiries as to his appearing to answer any and all questions concerning his patented design anytime and anywhere. Please respect his privacy during normal sleep times Eastern Std. Time- ty
This direct quote in Merrill Kellers words are taken from his website....
thank you for reading ..........Neil C.


I seek financial investor or purchaser for my advanced helicopter rotor system. This system is the only viable current helicopter rotor. (tip jet ) It's the simplest , safest, fastest & smoothest system . This system is very similar to Boeings latest offerings the (X-50) in infrastructure except for the main rotor. The main rotor of any helicopter is what determines helicopter type. I have contacted Boeing ( MESA Arizona Advanced Rotor Systems ) and continue to wait. ( I am tired of waiting ) My system is ideal for the Tip-Jet Rotor . I would like to build a small prototype a ( proof of concept ship ) or let others take on the project ( I will serve as consultant ) This design is the future of helicopter technology.

Merrill M. Keller

[Victor Duarte]

Hi Neil,
i love tip jets, an ideal pre rotator and de - icer.
Let me know more about your interest in that. Are you a part of Keller's project ?
thank you

[Neil C.]

Zeooo,
No sir, the only part I play in Mr. Keller's project is to try to bring some awareness to his patented design through use of the internet since he has no computer and does not know how to surf to forums like this one. I don't know why it took me so long to find ANY discussion on tip-jets, I am glad that I did. Mr. Keller told me he has a friend in the FAA who informed him that Sergio Sikorsky had been in the former Soviet Union recently having something to do with new discoveries in tip-driven technology. Perhaps some of the first new developments we will see in tip-driven technology will be in the unmanned area. I believe Sikorsky has just acquired a company that specializes in this area.
Thanks for the reply,
Neil

Here is the link to Mr. Keller's patent as it appears on the U.S. patent offices website
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=5,984,635.WKU.&OS=PN/5,984,635&RS=PN/5,984,635

Here is a New Link to Mr. Kellers webpage until his Domain is active, if it changes again, I will repost it..for now..this should work..thank you.
http://www.lowdollerhosting.com/keller/index.shtml

[Jan Verhoeven]

Hi guys, here's a drop from Holland. I've read the articles with interest, for techniques and discussions or fantasies about possible techniques have my interest. (ever seen "the sixth day" with Arnold S.? that's something to check out!).
Anyhow, from 1952 there have been a bunch of Dutch engineers (Verhage, Meier Drees and Kuipers among others) that started a foundation SOBEH to develop a small tipjet driven helicopter. It was named Kolibrie and after a few mishaps (oh dear, how sad, never mind) a Netherlands Helicopter Industries production of 11 NHI-H3 Kolibries were successfully built. The ramjet tipjets were built by Kromhout (that is "warped wood" although the blades and engines were (light- and) metal made). Quite a few have several hours made as cropdusters in Israel. Check at: 1000aircraftphotos.com/HistoryBriefs/NHI-H3.htm and you'll be surprised. For yaw control a small Austrian moped engine propels a tailrotor, this engine was also used to gain initial main rotor rotation (via a clutch) necessary to combust the ramjets. And indeed high fuel consumption but it ran on cheap paraffin! There is still a craft at Lelystad museum and in my instruction classroom I have a rotorblade with tipjet!

So everything has been done before as you already have encountered; The games began in 1842 by W.H. Phillips in England with a flyable prototype copied by quite a few successors, some rotors driven by hot or cold gases, some even by piston engines with propellers at the bladetips!
Even in this frog-country as we call our kikkerland someone obviously tried rather successful.
And last but not least from very small to very big: How about the Hughes XH17? 130 feet diameter gasdriven rotor! That’s something to think about I guess…

Thank you for your attention,
Kletsmajoor Jan.

1000aircraftphotos.com/HistoryBriefs/NHI-H3.htm

[Neil C.]

And last but not least from very small to very big: How about the Hughes XH17? 130 feet diameter gasdriven rotor! That’s something to think about I guess…
....whats there to think about?..They tried it and scrapped the project...another failure at tip-driven design....they've tried EVERYTHING except one thing...a tip-driven rotorhead with multiple short span blades attatched to a frisbeeshaped lifting body to unload the blades for faster forward speeds...no-one has tried it...there's nothing left to try. Conventional rotorheads are based on 40's technology plain and simple...at least...that's what Merrill Keller says. America needs this design.
thanks

Neil C.

[Victor Duarte]

Hi Neil and Jan, i am trying to work on a cold tip-jet prerotated rotor...
i 'd really appreciate your sharp expertise.
i can obtain 0.8 kgs/sec of airmass at 3 bars...
What do you think of that ?

Neil, sorry, i didn't see your reply was aimed at me, stupid me.

cheers

[Neil C.]

Mr. Kellers site is up for viewing... www.pressurejet.net
those interested in tip-driven technology may find this site interesting. His patent is FOR SALE and Virgin Airways of the U.K. is in contact with Mr. Keller. Seems as though only the Brits are interested in THE MOST MODERN ADVANCEMENT IN TIP-DRIVEN ROTOR TECHNOLOGY TO DATE.

[hstearnsjr]

Hi,

I was involved with Dr. Bruno Nagler and Gene Liberatore when they were devoping
cold cycle pressure jet helicopters in Phoenix, Arizona. I was there for some
of the prototype flights. These were very quiet -- All I heard was a hissing of the
tip jets + engine noise.

For yaw control, all one needs do is have a small electric motor geared to the
rotor shaft. For left yaw just use it as a generator (or just grip the shaft with a brake).
For right yaw, just add a bit of power to the motor.

I patented a method to increase the efficiency of tip propulsion by putting
electric powered cross flow fans in the blade tips, which provides 10 times the airflow
of central blown blades. See patents 4,702,437 and 4,720,059.

These 75 HP motors are only 3 cm in diameter and weigh only 10 pounds.
This kind of propulsion also causes an anti-coning gyroscopic couple to the blades.

For some history see "Cold-Cycle Pressure -Jet Helicopters--Ventures, Designs,
& Developments" -- E.K.Liberatore Vertiflite Nov-Dec 1991; Jan-Feb 1992, Mar-Apr 1992.

(An American Helicopter Society publication) http://www.vtol.org

See

http://www.turbotip.webhop.net/nagler.html
http://www.turbotip.webhop.net/airjet.jpg

http://members.cox.net/hoyt-stearns for my latest project :-)

[helipilot]

Can you confirm the www.turbotip addresses - couldn't find the pages

[hstearnsjr]

You're right -- I'm having trouble with the free Yahoo website myself
(which the turbotip URL's redirect to).

I guess I'll have to move the site to my cox.net account (Maybe Yahoo wants
me to pay for an upgrade :-( ). Anyway, keep trying http://www.turbotip.webhop.net
and if you can get in, you can get to the pages of interest.

[helipilot]

Thanks for reply re: web pages. Managed to get a quick view of patent docs before te site went again. Couple of questions:
1. I saw that you were proposing a gimbal arrangement for pitch and roll and not using direct aerodynamics on the rotor blades, what about increased lift - ie collective equivalent, increased rotor speed?
2. Whar sort of motors were you using? 75 hp out of 10lbs at 3cm dia is fabulous. And can you be more explicot about cross-flow fans?

Cheers

[et3dotcom]

I did some work on the American Air Jet pressure jet helicopter in Colorado springs in the mid 80's The prototype did not have quite enough power to sustain HIGE. It used a 300 horsepower Mazda 13b turning a turbine air compressor through a speed up gearbox. if i remember correctly it put out 5lb/sec at 80psi, (my papers on it are in storage now). The rotor blades were fiberglass. It was very loud, the engine especially, the turbine compressor was shrill, and the tip jets were not quiet either. I do not know what happened to the project.

[hstearnsjr]

Thanks for reply re: web pages. Managed to get a quick view of patent docs before te site went again. Couple of questions:
1. I saw that you were proposing a gimbal arrangement for pitch and roll and not using direct aerodynamics on the rotor blades, what about increased lift - ie collective equivalent, increased rotor speed?
2. Whar sort of motors were you using? 75 hp out of 10lbs at 3cm dia is fabulous. And can you be more explicot about cross-flow fans?

Cheers

Tilting the rotor shaft (ala Benson etc.) is almost exactly equivalent to using a
swash plate and IS using aerodynamics. It's feasible in a tip jet 'cuz there's no
transmission. In practice I'd use a 3D Peaucellier virtual pivot so there's no
mechanism above the fuselage, reducing drag enormously.

Collective is done in the conventional way with a slider up the center of the
rotor shaft (as in Rotorway Scorpion).

One difference shown in the patent is the possibility of using just one
stick for collective, cyclic, yaw and throttle. You move the stick up and down
for collective, twist the grip for yaw. Perhaps another small twist grip for throttle.


The motors are rare-earth permanent magnet synchronous machines providing
2 horsepower per Inch of length, spin about 200,000 rpm and are powered
by 3-phase AC at about 3000 Hz, as I recall. They use air bearings.

Cross flow fans are long thin hollow vaned squirrel cage blowers. The
air actually flows through the center. Their behavior is not obvious by inspection.

Neodymium/Iron/Boron magnets are incredibly strong. I bought a few to play
with and they can be hazardous to your fingers if you get them stuck between
two 1" cubes ( I know, I've been pinched severly several times :-( )

If they do get stuck together, it's really hard to pry them apart. If you use a vise,
now they're stuck to the vice.

[Rotor Rooter]

If there is still an interest in Tip Jet Helicopters, pages 23 to 55 of the following NASA report may be of interest.
Stepniewski, who has probably done more comparative evaluations of rotorcraft concepts than any one else, wrote it in 1992.

Open Airscrew VTOL Concepts (232 page 'pdf' file) (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008694_1993008694.pdf)

Dave

[quadrirotor]

Thanks Dave, there are hopes for a small homebuilt helo with cold air tip-jets! but may be, the main problem is the noise: a good project for universties! Overall efficiency could be today a lot more than forty years ago: light but powerfull diesel engines, new compressor technology, access to low cost fuels...
I think that the best potential is for gyro...We could get back the anyway wasted energy of the exhaust with a turbo to power a good prerotator and have added power on the rotor to conteract low G situations (and icing conditions as turboed "cold" air is not so cold...). The power for prerotation is not so high, so the problem of the noise is not a big deal...No reaction torque to conteract...The added weight could be lower than the weight of the no more needed mechanical prerotator and muffler!...the efficency is more than 100% as the rotor works in a better way and we recycle the anyway wasted energy!...
But for a very efficient, safe and silent homebuilt helo, the synchropter set up is unbeatable!... ;)

[Rotor Rooter]

This Root Turbofan Rotor proposal (http://www.unicopter.com/0002.html ) is a high volume / low velocity alternative to the tip rotor.
It may (or may not) have validity.

Also, it may (or may not) have been posted on this forum before. :confused:

[quadrirotor]

Yes Dave, in the same stream, you have the no-torque torque convertor and the helo of the sci-fi film "the 6th day" with Arnold...

[quadrirotor]

Why not for a prerotator! pressurized water through tip-jets! :eek: :eek: :eek:

http://www.lookatentertainment.com/nneu231nd1zd823/vids/v-1169.wmv

[Jan Verhoeven]

For serious work: MEG

[quadrirotor]

Impossible to see it flying!!!

[Cita]

I have a short clip on video of the MEG-1X (single blade rotor) hovering on a safety line.

Cheers Cita

[quadrirotor]

Cita, if you please, put your small video and get an URL, on:
http://www.putfile.com/
Thanks.

[Cita]

I would love to do this quadrirotor but I have the clip on a video tape not in my computer or on a CD/DVD.
It is taken from some old 8 mm footage and I have no idea how to put it on a CD/DVD.
My concern is that in the near future the magnetic video tape will loose all the images!!
Anybody has a solution for this?

Cheers Cita

[Brian Jackson]

I would love to do this quadrirotor but I have the clip on a video tape not in my computer or on a CD/DVD.
It is taken from some old 8 mm footage and I have no idea how to put it on a CD/DVD.
My concern is that in the near future the magnetic video tape will loose all the images!!
Anybody has a solution for this?

Cheers Cita
For videotape, get a video capture card for your PC and digitize it to your hard drive.
http://www.pinnaclesys.com/PublicSite/us/Home/
Pinnacle Systems makes a good video capture card... I use one myself. The software that comes with it (Studio 9) lets you make decent edits, etc. as well. Once the raw footage is captured you can export it as MPEG, AVI, WMV, or pretty much any standard format. I'm fond of WMV because the compression quality is good for a small file size.

For around $100 US you can get a system that will let you transfer all of your analog tapes into digital format. It's worth it. BUT... you should have a fairly fast hard drive (6MB/sec. sustained transfer rate). Most drives today will perform that way however.

[Jan Verhoeven]

Here's one photo of the thing flying

[Jan Verhoeven]

And the one bladed rotor with the jet-tip. Note the gas bottles on 's mans back, also a two bladed version.

[karlbamforth]

I like the last pic which shows it mounted directly on top of his helmet. Talk about keeping it simple. LOL

[karlbamforth]

Mr. Kellers site is up for viewing... www.pressurejet.net
those interested in tip-driven technology may find this site interesting. His patent is FOR SALE and Virgin Airways of the U.K. is in contact with Mr. Keller. Seems as though only the Brits are interested in THE MOST MODERN ADVANCEMENT IN TIP-DRIVEN ROTOR TECHNOLOGY TO DATE.

Neil C, for some reason I cannot access the website you listed is there another site or would you be willing to send info direct to me by Email ?

[karlbamforth]

Take a look at this link.

Jerry May seemed to be going along the right lines untill the accident.
Admittedly 26GPH is way too much and needs reducing to make it viable.

I still think this can be done with a bit of ingenuity, just got to get away from those thirsty turbine engines.

http://www.helis.com/timeline/may.php

[Ga6riel]

The MEG 1, -3 is also a product of EMG and the engines are a design by Eugene Gluhareff. These various configurations have seriously limited autorotational capability, and as is pointed out are high fuel consumers. They use propane (aka LPG) and need pressure cylinders to carry them. The photos you show of a MEG-1 flying are probably the only ones in existence since the thing was created. For a read of the report on the loss of autorotation look here:

http://naca.larc.nasa.gov/reports/19...ca-tn-2154.pdf

[karlbamforth]

Remember the fairey rotordyne.
Try this link and click on the "preview movie" button.
http://www.british-helicopters.com/aircraft__23.php#

Even better try this one for the Fairey ultralight.
http://www.british-helicopters.com/aircraft__30.php

[Biggles]

Thanks to HeliDev for raising the question of the use of jet tipped rotors. I have done a lot of research on both the so called cold cycle jet tip which is not really cold air. Running about 30 PSI gauge pressure (44.7 lbs. Abs) the nozzle temprature after heat losses will be 150 degrees C. The nozzle velocity will be about 1200 F/Sec , still subsonic at that temperature. Noise is not a big problem because the wake speed will be reduced by the tip speed. Without working out this example exactly you would need about 3 lbs./sec. of air to give you 100 lbs. of total dynamic tip thrust. There two conflicting factors for the choice of rotor tip speed. The faster the tip speed the higher the rotor net HP and the lower the required blade angle of attack. The lower the tip speed the more resultant rotor torque but more torque is required, the best compromize may depend on the gyro speed required.

That's what it takes for a very nice safer type of helicopter, compressors are no great problem but it does require a reasonable amount of power to hover. This is because there is a loss of energy absorbed by the air mass being accelerated on its way in a spiral to the tips.

The resulting helicopter will be extremely easy to fly as there is no torque reaction. A rudder needs to be in the prop. wash and rudder hinges can be angled at 45 degrees to use the down wash in hover and still be effective at speed.

I have designed and built what I call re-heat tip jets and they have a great future if they are used right. The Rotodyne was the greatest heavy lift coumpound helicopter ever designed but it was destroyed be government stupid decisions and corporate indecisions.

We are just scratching the possibilities, we should be considering going to 3 blade (folding) rotors to improve handling qualities and therefore safety of helicopter and gyros. Lets hear what you think - thinkers.

Kind regards, Biggles

[Ga6riel]

hey Biggles
Your right about the Rotodyne, its one of a chain of crazy decisions the Govt made there.

3 Blades arnt common because they are more expensive and less easy to hangar /transport. Also the setup time is greater. Besides a lot of people seem happy witht the performance available from 2.

It occurs to me, on the cold cycle machines, is a turbine really necessary. I shudder to mention pulse jet engines as the fuel performance is terrible but does something like that stand a chance?

Edit: I perhaps should have suggested the broader term "gas generator"

[quadrirotor]

All have been thought:
http://www.vstol.org/
French rotorcraft

[Ga6riel]

quadrirotor
you mean like electric cars and space travel too right.....

[quadrirotor]

Yes, indeed Ga6riel:

The "jamais contente" in may 1865, the first electric car:

http://upload.wikimedia.org/wikipedia/fr/thumb/e/ea/Jamais_contente.jpg/400px-Jamais_contente.jpg



By Jules Verne in 1865, "De la terre à la lune";

some details of the space rocket:

http://www.fourmilab.ch/etexts/www/talune/fig39.gif


The take off:

http://www.fourmilab.ch/etexts/www/talune/fig41a.gif

[Ga6riel]

what exactly are you saying quadrirotor?

[Jan Verhoeven]

Don't always believe what you see, hear or read. It might be possible but sometimes in a slightly different way.;)

[Victor Duarte]

http://video.google.com/videoplay?docid=6943201001782160188

this works

[autorotate]

i would doubt the turbos have the commpression power for this. or at least to be efficent. many air compressors have alluminum jugs and pistons wouldnt be th lightest but probably cheaper

[gyro]

I just saw this video today...RC turbin engines strapped to the guys leggs....way Cool!!

click here http://www.alexisparkinn.com/aviation_videos.htm#Videos
and scroll down to the skydiving section click on jetdiving.

[Jan Verhoeven]

Gleat Tlicks, Aalsoo froom Fiinlaand!

More rocket propelled items? Eat this::eek:

[helipilot]

Decided to pick up this thread again as now have more timeto investigate. From what you said about total power (75 HP) and power per inch of motor it would seem these things are about 3ft long? Do you know who manufactured them and if they are still available?

[quadrirotor]

Have a good time!
http://www.pulse-jets.com/

[karlbamforth]

Thought these might be of interest. I found them in an old magazine that was given to me recently. I tried to upload them but they don't view too well on here, so try my website at this link http://www.ckaviation.co.uk/Rotordyne.htm
and click on Rotordyne ads.

[Cita]

The Rotordyne hmmmmm........
Probably the biggest scandal in rotorcraft history !!!!!

I would like to find out the real reason why the Rotodyne project was cancelled.(instead of the redicilous noise issue they (gov.)claimed)
It simply is beyond believe that any gov. would end a project that was so promising, with unbelievable performance,even at today's standards,and with a HUGE potential of costumers!!!!!
I think almost every major airline in Europe was HIGHLY interested !!

Sad but true.

Cita.

[karlbamforth]

Cita,
Basically it came down to political pressure. Something was going on behind closed doors in parliment.

The official version is that due to development in rocket technology there would be no future requirement for manned military fighter and bomber aircraft.
The goverment used this reason to remove funding from several projects, Rotordye, Fairey Ultralight, and TSR2 are but a few. Companies were then forced into unwanted partnerships with the threat of no further funding for projects or military orders if they refused.

Once the UK Aviation companies were reduced to a few large partnerships the decision based on rocket technology was reversed, this was too late for the Aviation companies.

[Cita]

Hi Karl,

yes I know that it was politicaly manipulated but, if memory serves me well,
I believe that a lot of the tools and moulds where rapidly destroyed after official cancelation of the project,why? It can hardly be explaned by lack of storing space in those days.
Had Sikorsky and Bell so much influence on the US gov. that they could force the British gov. to back off?

It is possibly one of the weirdest things ever happened in rotorcraft history and up till today no serious explanation (other than the noise or rocket path)
was ever given by the British gov. or sought by aviation journalists.

Can you imagine what the rotorcraft scenery would look like today if the Rotodyne had 40 years of R§D under it's belt?

Cita

[karlbamforth]

Hi Cita,

I agree, but it wasn't just the Rotordyne that suffered.
The TSR 2 was similarly ordered to be destroyed along with all its jigs. Its a miracle that we still have a couple in museums.

At about this time Britain was in the race to break the sound barrier. The company concerned was ordered to hand over all information to the USA and destroy the aircraft and jigs. The British aircraft was to be fitted with an all flying tail, which was to be the secret to breaking the sound barrier safely.

America received the recognition for breaking the sound barrier, but only after incorporating the British modifications.
The handing over of such sensitive information albeit to allies is tantamount to industrial espionage.

Someone was applying political pressure, who, is anybody's guess. One thing for certain it destroyed a lot of the British aviation industry and a number of technologically advanced aircraft.

All that is history now and fuelling conspiracy theories doesn't help. All we can do is try again. :D

[Mike G]

Ranger
I don't follow you when you say that the time the TSR2 was scrapped Britain was in the race for the sound barrier.
If I remember well the TSR2 was scrapped in the 60's, Yeager went through the sound barrier late 40's or early 50's.
From what I've read the TSR2 was certainly scrapped to maintain the "special relationship" between GB and the US and due to US pressure on the GB government at the time. One of the biggest behind the scenes forces for scrapping the TSR2 was Lord Mountbatton.

Mike G

[karlbamforth]

Hi Mike,

I have just reread my post and you are right.
I didn't type what I was thinking. :(

I believe the aircraft that was destroyed and all information handed over to the USA was the Miles Aircraft Company M1. Thats just from memory I may be wrong.:eek: again.

[Ga6riel]

Cita,
Basically it came down to political pressure. Something was going on behind closed doors in parliment.

The official version is that due to development in rocket technology there would be no future requirement for manned military fighter and bomber aircraft.
The goverment used this reason to remove funding from several projects, Rotordye, Fairey Ultralight, and TSR2 are but a few. Companies were then forced into unwanted partnerships with the threat of no further funding for projects or military orders if they refused.

Once the UK Aviation companies were reduced to a few large partnerships the decision based on rocket technology was reversed, this was too late for the Aviation companies.

in addition to the pressures on the TSR2 was the advent of the marketing of the F111, and the govt of the day in my view unwisely decided not to give the indigenous aircraft industry oxygen at this critical time. For after the industry had funded these major and creative projects, they were well out of cash. And for in the end not to receive the blessing of contracts spelled death to more than a few.

More to the Rotodyne, the tip jets made considerable noise that has been noted, (this was also put to the Concorde project). They never had the chance to develop a quieter tip jet and the prototypes were quite wastefully cut up. So ordered by the govt of the day. (how does one say chinook)

Any successful adventure with tip jet technology needs to conquer these points.
1 Be considerably quieter
2 Positively eliminate the potential for ground fires
~~~and were sustained operation is envisaged, re helo ops
3 Be considerably more fuel efficient

[Ga6riel]

Ah yes
I had forgotten to explain
that since various Govt commisions had put up cash for the development of some of these projects, and I speak in particular of TSR2 and Rotodyne. In their consuming wisdom they (the govt) decided that they owned the results of the development. That being the machines (entire) the tooling and jigs, and the intellectual property therein.

The dilema for the industry became this, that being now without cash they could not fund future adventures. And the Govt couldnt be relied on to maintain their secrets, to be fair to them in contracts, or to further their needs.

To this end, much of the business consolidated into just a few groups and much was sacrificed to keep the Harrier, the Concorde project, and Rolls Royce in tact.

[Cita]

When the noise issue was brought up by the gov.as probably, being the major reason for canceling the whole project,the engineers succeeded in a very short time to reduce the noise by an enormous amount.
This must have scared the gov. cause very soon after this achievement the project was canceled and the engineers never got the chance to solve the problem as they probably could have.

Cheers Cita

[Ga6riel]

As I recall it, it was the customers that had complained first about the noise issues with Rotodyne. Although there was considerable interest, including letters of intent from various airline concerns.

Okanagan Canada
Japan Airlines
New York Airways
Chicago Helicopter Airways
British European Airways (BEA)

When the contracts were carefully examined, all included 'out' clauses about the noise concerns, (said to be audible from 10 miles away) which Fairey had contested were resolvable. In the end events, when Fairey was absorbed by Westlands, no such fix existed, and the project was cancelled.

It was indeed a sad event for such a promissing and safe design. It is my belief, that if Fairey had shown the expertise demonstrated in design of the Rotodyne toward its contract execution and its handling of high government beaurocrats it would be flying today. What is more, if the jet-tip engines issue can be solved, I see no reason it should not be revitalised.

[quadrirotor]

Related topic:

http://www.rotaryforum.com/forum/showthread.php?t=7858

[hstearnsjr]

Decided to pick up this thread again as now have more timeto investigate. From what you said about total power (75 HP) and power per inch of motor it would seem these things are about 3ft long? Do you know who manufactured them and if they are still available?


The motors are made up of 2 inch sections totaling about 3 feet with air bearings -- they spin at 200,000 rpm.

They would have to be custom designed, but I've contacted a famous
motor consultant who will do that , Peter Campbell, Hollywood Calif.
formerly with PA technology. I've found that high power to weight motors
are difficult to find off the shelf :-( . The users have them custom designed.


P.S. I now have a Mosquito ultralight helicopter. I've thought of
putting a 600 lb/ft electric motor in place of the top sprocket.
Some electric car wheel motors fit the bill but the manufactures of such
things aren't reallly interested in selling them to small users :-(.

( See my project website:

http://members.cox.net/hoyt-stearns

and my latest practice video:


http://HoytStearnsJr.webhop.net/TPCHovers.wmv

[quadrirotor]

Any more news??? :spy:

[yolandbeaudet]

Does someone khow how many CFM cubic feet minute at what pressure PSI
a rotorcraft like the french DJINN would need?

[Brent_Brown]

As small as jet motor are today why not use them?

[quadrirotor]

yolandbeaudet wrote:
Does someone khow how many CFM cubic feet minute at what pressure PSI
a rotorcraft like the french DJINN would need?

Tu as quelques infos sur l'hélicop-jet qui est un quadri-pales. J'ai quelques documents intéressants, envoie-moi un email, je te les ferai parvenir en retour.

http://celag.free.fr/museum/index.htm

[Cita]

Hallo André,
nu we toch in een andere taal bezig zijn (?),ik ben ook geinteresseerd in de Helicop-jet informatie.
Moet ik je een e-mail sturen?:)

Cita

yolandbeaudet wrote:
Does someone khow how many CFM cubic feet minute at what pressure PSI
a rotorcraft like the french DJINN would need?

Tu as quelques infos sur l'hélicop-jet qui est un quadri-pales. J'ai quelques documents intéressants, envoie-moi un email, je te les ferai parvenir en retour.

http://celag.free.fr/museum/index.htm

[quadrirotor]

Part of those threads are related to tip-jets:

http://www.rotaryforum.com/forum/showthread.php?t=13103

http://www.rotaryforum.com/forum/showthread.php?t=7858

[Victor Duarte]

Yes andré, maybe we should leave Dave's thread..:D

[quadrirotor]

An other very educational video about the Voljet tip-jet helicopter:

http://video.google.com/videoplay?docid=-7767672928209629808&q=tip-jet+helicopter&total=1&start=0&num=10&so=1&type=search&plindex=0

[Mike G]

I joined in other threads about tip jet systems before reading this very long and informative thread. Maybe I can help in some way because understanding centrifugal compressor performance is part of my job.

If you're looking for a simple off the shelf compressor for this sort of application the Rotrex supercharger seems a good starting point. There is a reference to it earlier in this thread.
One of the good things about it is that it gives a performance curve of the compressor and reading these curves gives a good idea of the expected efficiency and this allows us to calculate the discharge temperature and power absorbed.
If you take the biggest compressor they have, the C38-81, the best operating point would be at 0.475 kg/sec (62.7 lb/min) that's 1395 M3/hr (871 ACFM) at sea level and would give a discharge pressure of 1.75 bar (25.4 psi) with a temperature of 140°C (284°F) and require 61 kW (82 HP).
You would need the pulleys to get the input speed up to 12,000 rpm.
If you really wanted more pressure you could put two in series with intercooling.
I hope this is some help.

Mike G

[Mike G]

Another supercharger manufacturer that could be a good basis for this application.
http://www.procharger.com/models.shtml
Their biggest compressor delivers 2.3 kg/s (5 lb/sec) at 3.1 bar (45 psi) which would need 420 kW (564 HP) to drive it. They don't give any performance curves so it's not sure if the max flow (4000 ACFM) is at max pressure. Probably you'd get about 3100 ACFM at max pressure.

Mike G

[ruxpin76]

As I was drifting off to sleep, I was considering the hydrogen peroxide tipjet system and the webpage about the augmentation... Then I had this thought...

What if a standard gluharoff (sp?) tipjet was used, but had a fuel injector nozzle at the ignition site, and further downstream (toward nozzle) had a water injector? The vaporized water would instantly transform into steam and increase the mass the combustion was pushing against. Combined with standard augmentation device, this might allow you to use a smaller tipjet with greater efficiency. This would allow less fuel consumption and potentially lower noise...

I don't have a tipjet, otherwise I'd try it... Thoughts?

[Victor Duarte]

Mike,
glad you joined the discussion and i think you are an asset in the debate.

i don't understand how you determine the HP required to run the procharger 564 HP !! (the engine must be at least 1500 HP or more to have one !!).

the rotrex numbers are not exact.

here is a message i got from ROTREX themselves :

Good Day Mr. Duarte
Interesting project. I would like to se some sketches of the gyrocopter
since I was involved in a similar project earlier.
Our largest can produce about 0,8kg/s at free flow.
At that flow rate the power consumption is 70kW.
I am not sure of your construction, but if you fitted a supercharger to the
engine for increased performance and had a powersupply from the engine to
speed up the rotor that would work.
Kind regards, Anders
in your DOC you use the supercharger at only 50 % of it's capacities, i think you could use it at 75%, no ?

Mike, i don't know if we talk about the same machine : i have in mind an ULTRALIGHT helicopter, something like the Dornier DO 32.

Yes you can use 2 units to produce enough air, but i don't understand why in serie... if you cool air , then suck it into another compressor, the temp will rise again , not the pressure, unless it is a bigger unit (or am i wrong).
I think the ideal setup is 2 units in parallel.

The temps you quote sound correct, they are those i had in my numbers.
at 125 °c you could use composite blades with a kevlar hose , maybe an insulated one.

i think the improvements on tip jets can be done on the nozzles, their placement and their shape..

i will try to post pics of the Fairy rotodyne nozzles, very educating.

Thanks

[Bruno]

What if a standard gluharoff (sp?) tipjet was used, but had a fuel injector nozzle at the ignition site, and further downstream (toward nozzle) had a water injector? The vaporized water would instantly transform into steam and increase the mass the combustion was pushing against. Combined with standard augmentation device, this might allow you to use a smaller tipjet with greater efficiency. This would allow less fuel consumption and potentially lower noise...

I don't have a tipjet, otherwise I'd try it... Thoughts?
Water injection does work. Yes, it will improve performance. However, it will also increase complexity and weight.

At the same time, it will not solve the big problems of rotor-tip jet engines, like the aerodynamic drag. If you could shrink a Gluhareff engine to a quarter of its bulk, you might have something there, but unfortunately it is not possible. So, the moment you cut power off, the rotor starts slowing down fast, braked by those big gobs mounted on blade tips.

Another problem is noise. Those engines are NOISY. Tipjet engines will not win you friends in the local community.

If you want your rotor jet-powered, pumping gas through the blades and having just the exit nozzles at rotor tips seems to be a better idea.

[Mike G]

Mike,
glad you joined the discussion and i think you are an asset in the debate.

i don't understand how you determine the HP required to run the procharger 564 HP !! (the engine must be at least 1500 HP or more to have one !!).

If you look at the Protech data the supercharger was for a 1000 HP engine before supercharging so it is a very big unit probably for a boat or truck.

the rotrex numbers are not exact.

here is a message i got from ROTREX themselves :

Good Day Mr. Duarte
Interesting project. I would like to se some sketches of the gyrocopter
since I was involved in a similar project earlier.
Our largest can produce about 0,8kg/s at free flow.

At that flow rate the power consumption is 70kW.

Could you ask for a preformance curve of this compressor?
For the application we have (atmospheric press and temp at inlet) the absorbed power can be considered as being the discharge press times the mass flow. This is a major oversimplification just to give you an idea of how it works. Therefore when you ask Rotrex for the maximum flow, he'll give you the max flow but doesn't tell you it's at minimum pressure

A compressor drawing 15°C air at sea level delivering 0.8 kg/s and absorbing 70 kW would only be giving a pressure of 1.1 bar (16 psi).

I am not sure of your construction, but if you fitted a supercharger to the
engine for increased performance and had a powersupply from the engine to
speed up the rotor that would work.

I don't think he's really understood what you're trying to do, he's a supercharger guy and cannot imagine not using his supercharger for something else.
Kind regards, Anders[/COLOR]

in your DOC you use the supercharger at only 50 % of it's capacities, i think you could use it at 75%, no ?

In my doc the compressor was limited to 90,000 rpm so if you follow the 90000 rpm curve you see that as the flow increase the pressure decreases. You're looking for the best compromise of flow and pressure. You need the pressure to be able to squeeze the air down the blade with the minimum of losses.
Attached is an excel spreadsheet that shows the Rotrex performance curve as discharge pressure and absorbed power against flow. You can see that as you increase the flow you loose pressure.

Mike, i don't know if we talk about the same machine : i have in mind an ULTRALIGHT helicopter, something like the Dornier DO 32.

I don't really have anything in mind except perhaps a pre rotation system, I'm just interested in the thermodynamics of this and offering my bit of competance in compressors to try to prevent you guys wasting time by misunderstanding the limits of centrifugal compressors.

Yes you can use 2 units to produce enough air, but i don't understand why in serie... if you cool air , then suck it into another compressor, the temp will rise again , not the pressure, unless it is a bigger unit (or am i wrong).

Zeeoo, yes your wrong but it's not surprising, not many people understand these compressors, that's why my company hired me.
If you cool the discharge air of the first compressor you reduce its volume and in fact you need a smaller compressor for the next stage (even though it'll probably absorb more power). You're right of course the temperature will rise in the second compressor and and may still need to be cooled before you put it in the blades.

I think the ideal setup is 2 units in parallel.

Putting two compressors in series only increases the pressure, you're right that if you want to increase the flow you need two in parallel, but as I said above you need a higher pressure to get the air down the blades more than you need mass flow.

The temps you quote sound correct, they are those i had in my numbers.
at 125 °c you could use composite blades with a kevlar hose , maybe an insulated one.

i think the improvements on tip jets can be done on the nozzles, their placement and their shape..

I've collected some data and when I find time I'll try to do some calculations to see how they work. The nozzle was (still is) the weakest part of my understanding of this system.

i will try to post pics of the Fairy rotodyne nozzles, very educating.

Thanks


Zeeoo
I've tried to reply within you message but am not sure if it will work.

Mike

[quadrirotor]

Rare footage of tip-jet helicopters!!! :)

http://www.youtube.com/watch?v=3vsMBYgme64

[PeroxidePropuls]

I just wanted to let you know that the former Intora Firebird is flying again!
The new owner is Swisscopter. They have re-named it Dragonfly.
See http://www.peroxidepropulsion.com/news/the-dragonfly-tip-rocket-helicopter-is-flying

Erik

[Jens]

Great video.
What will the price for fuel, add up to for 1 hour of flight?

[PeroxidePropuls]

Hello Jens!
How is it Denmark?
The cost is not for you and me. Lets say 3-4 kg/minute and price about 5 Euro/kg (80% conc.).
This is why I believe more in autogyro VTO with tip rockets followed by conventional propeller engine flight after TO and tip rockets shut off. A VTO doesnt need to take more than 15 seconds. Not so expensive.
Mr. McGill who invented this type of tip rocket propulsion in fact had this idea all from the beginning. He called the gyroplane version "Configuration 3".
See http://www.aviastar.org/helicopters_eng/aerospace_minicopter.php
Even so there ARE customers that can afford the "Dragonfly". When they showed Intora Firebird at an air show in Abu Dhabi in 2002 (?), I have heard there were a lot of prospective customers that wanted to buy an Intora Firebird.
As far as I understand Swisscopter plan to again show the Dragonfly for prospective customers in Abu Dhabi in the near future.
So if you own an oil well or two its no problem, Jens.

[Jens]

...How is it Denmark?
The cost is not for you and me. Lets say 3-4 kg...../
Hello Erik.
"How Denmark is?" - I hardly know ;-)
I am on job in Norway most of the time. Not at an oil well, but designing equipment for oil drilling. Athough I am very satisfiered with my income, I agree with you that a peroxide driven helicopter or hovercopter is TOO expensive for me :-(

3-4 kg are excatly the same figures for my PPG - for an hour :D

[PeroxidePropuls]

Hello Jens,
What engineering company in Norway you work for? Kvaerner may be? I worked for Kvaerner 1996-2001.
Here is a cost efficient VTOL vehicle for us poor engineers:
http://www.youtube.com/watch?v=mAVpM2ozXi4

TO is with peroxide tip rockets.

[Jens]

...I worked for Kvaerner 1996-2002.....
Ohh, that’s not so long ago. You where at Korsvig, I think.
I work for Natoil - now NOV since 2007. A few kilometers further east of Kristiansand.

Yeah, gyro gliding could be fun, and I would dare it and would like to try it - but that don't really need rockets :)

[PeroxidePropuls]

Of course it is more fun to put the rocket system on a propeller driven gyrocopter and make VTO. It would work the same way as on the glider on the above movie, I believe.
We will make a test in 2 -3 months.

[Jens]

If it will be in Denmark by Ivan - then let me know.

[PeroxidePropuls]

Ivan has stopped flying since quite a long time. That was one reason why the evaluation of the system was delayed.
This time a guy in Indiana, USA will test the rockets on his Ken Brook gyrocopter with a Mc Cullock engine. I hope for more progress this time.
Erik
www.peroxidepropulsion.com

[Rotor Rooter]

Posted link because it may not have been previously posted.


Dragonfly Tip-jet DF1 (http://www.tipjetusa.com/index.html)

Made in USA

[BEN S]

Are they kidding? 120K for an ultralight style...hell I can get a used
Schweizer for that!
I was all interested as they are in AZ, too bad.
Ben S

[Eli-sir]

120K USD!!! And the fuel? 70% H202... here in Italy, for example, is very very difficult find it!
I think that the maximun price for this helicopter can be around 40-50 K USD (it don't have engine, transmission... the construction is "simple"), with this sale price is not the way to launch a new technology!

[Arnie Madsen]

What "they" call a rocket is actually a very nicely designed tip-jet that is as near perfect as could be hoped for in modern day. Especially when adapted to the tip of a rotor blade. The serious drawbacks and tremendous drag of old school tip-jets has largely been overcome .

The remaining problem is the consumption per flying hour of Peroxide Rotor Power.

Much has been accomplished in in the supply and safety of the fuel with promising forecasts for the future.

Still remaining is the high fuel consumption per flying hour. . Plan a 2 hour flight and calculate the gallons required and the weight , and the dollars. Then calculate if a peroxide powered machine could carry the fuel required for 2 hours.

I love the utter simplicity of tip jet rotors , But have learned to accept the mathematical realities . I hate mathematical realities . They interfere with men's dreams of powered flight.

The tip jet rotor is still on the top of my list for the future. Not everything has been made public yet. There is still one situation where the mathematics and thermodynamics look good. Practical testing have not dis-proven the numbers. Fuel supply is abundant , low cost, readily available , and fuel on board can keep us off the ground for 2 hours.

The fuel is not peroxide.

[Rotor Rooter]

Arnie,

What an intriguing post. :)

Dave

[Cita]

as far as tip jet is concerned,I would go for the Dornier 32 without a doubt.
Compressd air as tip jet power,it was done decades ago with the Djinn and the Do32 (same WWII era designer) so with modern technology....
Replace the over expencive turbine with a light weight 4 stroker to drive the compressor.
A 40 centimeter diameter centrifugal fan driven at 20,000 rpm will be need to be developed though.....Hmmmmm.


Cita

[Cita]

Posted link because it may not have been previously posted.


Dragonfly Tip-jet DF1 (http://www.tipjetusa.com/index.html)

Made in USA

That bird has popped up in about a dozen country's and each time it's "new technology".
The bloody thing has'nt changed much since McGill designed it years and years ago.
If HCP was widely available and sold to the price of gasoline perhaps.....


Cita

[Jens]

...There is still one situation where the mathematics and thermodynamics look good... .
a steam something?

[Bruno]

What "they" call a rocket is actually a very nicely designed tip-jet.
Arnie, but it is a rocket. A jet engine would be using atmospheric oxygen. A peroxide rocket doesn't.

a steam something?
Jens, the peroxide rocket is in fact a steam rocket.

[RotoPlane]

Arnie - On Post #174: Input....I crave more input......

[joe nelson]

Just imagine a Hiller Hornet built with modern technologies.

[Cita]

Just imagine a Hiller Hornet built with modern technologies.

Except for the engine,I wouldn't change much on the Hiller Hornet,it's as "modern" today as it was when it was developed :D

Cita

[joe nelson]

Good morning Cita,

I was thinking along the same lines as you. New engines built with newer lighter metals and carbon fibre airframe would reduce the the total weight. Composite blades would improve performance. The starter motor could eliminated again reducing weight. A 10-20% lighter Hornet would be faster, able to carry more fuel or payload.

All in all, I would still like to have one to play with!!!:wave:

[Cita]

Hi Joe,

reducing the weight by 20% on a helicopter that is allready lightweight can be a very nasty task.
I agree though that modern technology would make a "better",more reliable Hiller !!
It was a rather complex machine but I simply love the look of it !!!!

Cita

[kolibri282]

Sorry folks,

didn't have the time to check whether this one has been posted before:


http://www.agplane.nl/downloads/nhikolibriesmall.pdf


Cheers,

Juergen

[tyc]

I agree with Cita ... the Hiller Hornet is as I value such things, a good looking machine BUT ... as I understand it, the autorotational speeds were such that that they'd make a Brantly B2 series machine look like a "piece of cake." If I'm not mistaken, in addition to the noise, it was the high autorotational speeds which essentially killed an otherwise very interesting rotorwing project back then..

As to the issue of employing current technology with the Hiller Hornet, might not be worth it, as in my opinion, one might be better off with a complete redesign; i.e., start from scratch and end up with something like the Mosquito Air. While not a tip drive, at present it appears to be a very advanced rotorwing design in it's own right - and it's intended to be a "sport helicopter" to boot!

... just my opinion for what it's worth.

tyc

[leviterande]

Hi

What about an electrical ducted fan unit of 7kw-10kw:

see the motor here: (3060 and 3080 Series Motors)
http://www.finedesignrc.com/motorslehner.asp

Specifications
weight - 1.400gr
shaft - 10 mm
watt - 7000
volts - 6 - 60 -----free rpm/v choice variation from 500rpm/v to 1527rpm/v


------------------------------------------------------------------------------

see the fan here:
http://www.rcgroups.com/forums/attachment.php?attachmentid=598895


A 160mm fan
7000w at 20000rpm
Thrust at 70m/s 55 N


The motor weighs only 1,4kg so g-forces are minimal for such power
Gyroscopic forces are also minimal as the unit diameter is 160mm


Installing the units on the tips of 10m rotor and low rrpm, would be compared to installing small turbines. but electric is way simpler than jetturbines


even a flight of a 1min is a success with lead batteries

A 27hp 2stroke generater and a 16kw alternator are to be fit into the heli if tests show succes first with lead batteries

[PTKay]

The 8m diameter gyro rotor tip at 300 rpm (5 rps) will travel

4m * 2 * 3.14 * 5/s = 125 m/s

so almost double the design speed of this electric turbine...

Any slower rotor would have to be bigger, so the tip speed higher again.

:(

Do you honestly believe you can fly a helicopter on 14kW?

[hillberg]

Hi auto speed in a Brantly?:bored: I love to do zero / zero No collective autos in the old Bird:spy:-Zero / zero = no ground speed no decent on landing tuchdown.....Better than an Enstrom :sorry:IMHO....

[Rotor Rooter]

This motor may be of interest. EMRAX motor (http://www.enstroj.si/Electric-products/emrax-motors.html)
Price is approx. $3500 US plus controller ($?).
It is brushless, and they are now working on making it sensorless (http://www.unicopter.com/ElectrotorSloMo_Sensorless.html).

For a place to put it, I have hyped this idea before (http://www.unicopter.com/0002.html). It may or may not be practical from an efficiency point of view, but i really like the concept of having all of the thrust contribute to forward flight when in forward flight.


Dave

[leviterande]

The 8m diameter gyro rotor tip at 300 rpm (5 rps) will travel

4m * 2 * 3.14 * 5/s = 125 m/s

so almost double the design speed of this electric turbine...

Any slower rotor would have to be bigger, so the tip speed higher again.

:(

Do you honestly believe you can fly a helicopter on 14kW?

I was thinking of a light heli and wider chord blades. BTW werent those early tipdriven helis powered by a pair of small tubines/ramjet not more powerful than the electric motors above or am I wrong please? it is so confusing with all the semijet and jet tip mounted propulsors. is there even any static thrust and airspeed thrust for those ramjets

Somr tip copter flew with 16hp of total power, I think its called Nr-55?.
-------------------------------------------------------------------------------------------

Something smells fishy here:

Here you got two tip-copters:

The NHI Kolibrie uses 120hp

The Nagler NR-54 V2 uses 16hp!

Is the NR-54 for real?! did it fly? if so than a propeller is the way to go

[leviterande]

We all know tipdriven rotors are less efficient.:rolleyes: The main question is how much?:cool:

I have made some research and found some extraordinary but obvious results:
A prop driven rotor produces 3 times less lift compared to an equal system of the same discloading and power loading.:eek:


You can find some info on this Lockheed Martin Monocopter paper:
http://www.vtol.org/forum66/f66_bestPapers/aircraftDesign.pdf


3.3 times less lift
A RC 1,56m diameter monocopter is driven by a small tip mounted brushless motor. Total AUW is 600g and needs 72watts to hover. That is a blatant high power concumtion. At an extremely low (and efficient) discloading of 0.3kg/m2, the small monocopter still eats 120watt/kg which is a very huge power consumption. My much higher discloading RC helicopters have better efficiency. According to the paper the Figure of merit of the propeller/rotor efficieny of the monocopter is as low as 0.25 which is correct.

A mechanical powertransmission for a diameter of 1,56m and a power of 72watt, gives 2kg of lift instead of 600gram according to blade/momentum theory. 3.3 times HIGHER LIFT then the propeller driven monocopter:Cry:.

As with all the monocopters I found, I discovered offcourse that the tipmounted propulsor alone can actually lift the whole monocopter with its propeller.


A contradicting problem

I really wouldnt bother to burn some braincells if it wasnt for this: How come the Djinn helicopter managed to get such a relatively high efficiency?

240hp for 800kg at its discloading is not too bad at all and far higher then the propellerdriven monocopters. So why is the monocopter so much less efficient? Could it be the high drag of the propellers, combined with the fact that the Djinn had its airjets at the farthest distance from the rotorshaft?



Kalle

[leviterande]

I have tried some tests on a built tipjet helicopter in X-plane. I wanted to emulate the electric ducted fans on the tip but,...it is not easy at all, because there is only "tip-rockets" available in x-plane. Anyway I choosed a gross weight of 440lb. rotor diamter 33ft and tip rockets of 12.4lb-thrust each.


The hard thing here is to find out how much horse power a 12.4lb rocket is.
Trying to figure out the horsepower by: Horsepower (hp) = thrust-lb x velocity-fts/550
If you can help me out here to calculate the horse power it is more then aprreciated.

I run this heli without any rotor blades to determine the horsepower.(Well, I had to use ultra thin no resistance rotorblades). Without any blade resistanse the two tip rockets whirled at a horrific 780rpm at the 33ft rotor. That makes the rocket velocity to 1,300ft per second! Installing some 9 inch rotorblades to actually lift and fly the helicopter yielded a maximum rotor rpm of around 180rpm. Now here is the tricky problem.

How can I calculate the horsepower, when rockets have contant force through out the speed unlike propellers and fans.

Considering this calculation: Horsepower (hp) = thrust-lb x velocity-fts/550,
should I take the velocity measured when the rockets "flew-freely i.e. 1300fts" or should I take the rockets speed when they actually lifted the helicopter at 180rpm? (Apparently if I was to measure the 180rpm velocity, it means that the thrust in the calculation should be increased, ha?)

This is really confusing, any help is welcomed

Kalle

[quadrirotor]

An helico which can use cheap fuel!

YouTube - Hiller HJ-1 "Hornet" - Jet Helicopter (http://www.youtube.com/watch?v=YFF6zzpU3o8)


For the sound!

YouTube - Hiller HJ-1 Hornet hovering (http://www.youtube.com/watch?v=MV2lS5mUSj4&feature=related)

Again and again, Bensen could be the first!!!

http://www.aviastar.org/helicopters_eng/bensen_midjet.php

[Arnie Madsen]

Good videos Andre. Thanks. I am surprised how quiet the Hiller Hornet is.

[quadrirotor]

Biblic simplicity! :D


http://www.airindustriesresearch.com/siram/ramdesigns.htm

[joe nelson]

Andre,
The first ram jet looks very simular to the type use by Stan Hiller's Hornet. I have seen the videos of him mounting it to the blades and flying it. I'm not sure but I think it was in the 42# of thrust catagory.