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quadrirotor
11-08-2006, 08:12 AM
How could be feasible this homebuilt version of the X2 Sikorsky coaxial helico...

No swashplate, only collectives.
A blown tail for yaw, pitch and roll (differential elevator...)
teetering semi rigid rotors with Delta3...

May be like the Rotorfly on wheels with a blown tail, no swashplate, only collectives!?

Ga6riel
11-09-2006, 05:07 AM
im thinking you guys need to check this out

http://www.motisvirtualjetdesign.com/VIRTUALEXPERIMENTALCASESTUDIES.htm

quadrirotor
11-09-2006, 05:17 AM
Just for RC, too noisy, too inefficient, too dangerous...autorotation questionnable...a good drawing, only a good video game target.

Rotor Rooter
11-09-2006, 12:08 PM
Ga6riel,

Interesting.
It's proposed market is the same as Sikorsky's series of X2 craft.

Unfortunately the student's concept has a terminal flaw. Rigid 2-blade rotors will produce a horrendous 2P vibration. Sikorsky's earlier ABC coaxial had 3-blade rotors, which is much better, however vibration was the limiting factor to it's forward speed. It appears that the new X2 will have 4-blade rotors.


Dave

quadrirotor
11-13-2006, 05:21 AM
One of the first "homebuilt" coax with a blown tail!!! :D

Bensen hovergyro 1976.
http://www.aviastar.org/foto/bensen_hovergyro.jpg

quadrirotor
11-15-2006, 08:06 AM
As a matter of fact, this set up could be a good way to achieve the safest gyro...The Doublegyro! :D

(no swashplate, no collective...two gyro rotors... a smaller engine for prerotation and in flight power...)

The Buhl gyro could be a precursor...change the rotor by a double coax rotors...


http://www.rotaryforum.com/forum/attachment.php?attachmentid=17442&d=1134823774

quadrirotor
08-31-2007, 06:41 AM
For new news on the Rotorfly:

http://www.rotor-international.net/start.html

Rotor Rooter
08-31-2007, 10:23 AM
on the topic of small coaxial helicopters, and specifically Russian ones; ----

Coaxial - Kamov - Ka 56 (http://www.unicopter.com/1009.html)

quadrirotor
10-06-2007, 12:55 PM
The Rotorfly:
New videos, very enthousiasming!!!

ROTORfly.mp4 - YouTube (http://www.youtube.com/watch?v=PUefKj--X90)


The very very very simple mechanics of the Rotorfly:

Timchick
10-06-2007, 05:36 PM
In a coaxial helicopter like that how do the rudder pedals pivot/turn the fusalage without a tailrotor? What exactly are the rudder pedals controlling?

brett s
10-06-2007, 06:10 PM
In most the pedals would control either differential collective pitch or rotor tip brakes, in addition to actual rudder which would be effective at higher speeds - not sure with this one (fixed pitch, right?).

Jason O
10-06-2007, 07:52 PM
I am almost sure that this helicopter uses collective and cyclic on both rotors. I believe the upper rotor is controlled by rods through the center of the mast just like the Mini 500, the and the Helisport copters. You can also control yaw by putting a brake on the two different rotor masts. When you cause friction between a mast and the airframe, the frame yaws that way.

Jason

PTKay
10-07-2007, 12:47 AM
This looks to be really innovative.

The blade pitch control seems to be the same like Kaman,
with flaps on the trailing edge.

Simple teetering stiff hub bar.

Reliable and easy.
I really like it !!!
:)

Could be a solution for jump take off gyrocopters.

PTKay
10-07-2007, 02:45 AM
Kaman blades:

Sita
10-07-2007, 10:17 AM
....You can also control yaw by putting a brake on the two different rotor masts. When you cause friction between a mast and the airframe, the frame yaws that way......

Jason



Are you sure about this?:p
I think both rotors will slow down.....without any yaw at all.

Rotor Rooter
10-07-2007, 11:25 AM
Here is some information on the tip brake;

Control - Flight - Directional - by Tip Brake (http://www.unicopter.com/1235.html)

~ and even better; with pictures :) ~

Gyrodyne Helicopter (http://www.gyrodynehelicopters.com/xron_history.htm)


Cita;

I think it depend on how the two rotors are mechanically interconnected.
Here is a page related to this subject; Coaxial Transmission w/ Yaw Control (http://www.unicopter.com/0954.html)

Dave

Fly Army
10-07-2007, 02:58 PM
Isn't this the one that has no auto rotative capability ? I think I remember something about this one having a ballistic recovery chute. I could be mistaken though.

brett s
10-07-2007, 03:39 PM
They say "excellent autorotating qualities" on their website - from watching the videos it sure looks like it has collective pitch, must be using blade servo tabs as PTKay suggested.

Sita
10-07-2007, 10:19 PM
Cita;

I think it depend on how the two rotors are mechanically interconnected.
Here is a page related to this subject; Coaxial Transmission w/ Yaw Control (http://www.unicopter.com/0954.html)

Dave

Dave,

I think that, from the moment the two rotors are connected,in whatever way,it makes no difference which rotor you put the brake on for yaw.Both rotors will slow down because they are connected,giving no yaw at all.
The only way to achieve yaw through the rotors is via an aerodynamic force (airbrake for example like in the Rotorcycle) or via a differential gearbox (like in the Japanese GEN-4 UL co-axial helicopter).....I think.
One can allways use two sperate rotorsystems, each having their own engine and rotor operating idependantly from each other, but I think that this will be tricky to control but that's the only way I can think of to use rotor shaft brake force to create yaw.

Cita

quadrirotor
10-08-2007, 04:32 AM
Who knows what became those coaxial (Dennis Fetters, may be!?)???
And what are the intentions of Cicare about them???

http://www.cicare.com.ar/index.htm

Rotor Rooter
10-08-2007, 12:45 PM
Cita,

I agree, when you say that yaw control can be handled by the inclusion of a 'differential' in the gearbox.

This is the proposed method in the web page mentioned above; [Coaxial Transmission w/ Yaw Control ~ With larger version of drawing just added. (http://www.unicopter.com/0954.html)].

By clutching the central back-to-back crown gear to either the upper or the lower crown gear the relative rpm (and drag) of the two rotors can be varied + or -, thereby producing yaw. In addition, the pedals will not have to be reversed during autorotation.

By braking the central back-to-back crown gear the rpm of the two rotors will be equal, but opposite.

By the application of an incremental rotation of the back-to-back crown gear the crossing azimuth of the upper and lower blade can be changed.


Should you, or anyone disagree with this, please say so.

Dave

quadrirotor
10-08-2007, 12:56 PM
I am sure, Dave, that you can do simpler!!!

Fly Army
10-08-2007, 01:36 PM
On their technical data page at the bottom they list "Ballistic Recovery". Why ?????? and more precisely ...HOW ???

brett s
10-08-2007, 02:00 PM
I'm with you on that, makes no sense to me either - just wasted payload & money. Marketing hype only IMO...

If the rotors are still attached & spinning, no way you'll be able to deploy safely - if they aren't, odds of surviving are about nil regardless.

Sita
10-08-2007, 05:57 PM
Hello Dave,

I'm still pondering over your design but at first glance it seems to me that the forces will cancel each other leaving no yawing force.Like I said though I'm still try to grasp the idea (grin-grin)

cita

Rotor Rooter
10-08-2007, 08:04 PM
Andre,I am sure, Dave, that you can do simpler!!!Hell, anyone can make it simpler. This complicated transmission was designed for rotornaughts who enjoy maintaining more than flying. :)

Seriously, the only advantage it offers over 1 pinion and 2 crown gears is that it does not require pedal reversal during an infrequent autorotation.
It's just an idea from the Department of Demented Designs.

Dave
_____________________________
Edited to add a 'More Seriously'

You want something simple. I'll let you in on a secret; but don't tell anybody or I'll have to shoot you. :laser:
Go to Goggle and search on [ElectrotorSimplex]

quadrirotor
10-11-2007, 11:54 AM
Is anyone trying to reproduce the XRON?

http://www.gyrodynehelicopters.com/xron_history.htm

karlbamforth
10-11-2007, 07:24 PM
Hi Andre,

Not that I know of, but would be a great idea. Maybe we should get a few guys together and do it.

joe nelson
10-12-2007, 04:13 AM
Wasn't there a coax aircraft several years ago called the Pearch Eagle or something like that? It had two 503s as powerplants but couldn't autorotate so it wasn't a commerical success.

PTKay
10-12-2007, 08:04 AM
Wasn't there a coax aircraft several years ago called the Pearch Eagle or something like that? It had two 503s as powerplants but couldn't autorotate so it wasn't a commerical success.

http://avia.russian.ee/helicopters_eng/eagle_perch.php

Evolved into AirScooter....
Nolan works for them.

http://www.airscooter.com/

Fixed pitch rotor...

:eek:

PTKay
10-12-2007, 08:11 AM
Is anyone trying to reproduce the XRON?

http://www.gyrodynehelicopters.com/xron_history.htm

Continued here....

http://www.yoshine.com/home.php

Eazycopter... ;)

PTKay
10-12-2007, 08:14 AM
Servo flaps:

In Conclusion

As can be gathered from this analysis, the servo flap provides the whole helicopter with more stability with regard to angle of attack than other rotor control systems. It is easier to give wider margins for rotor blade flutter and it reduces the requirements for an AFCS to give good handling characteristics especially in gusts. It is lighter than other systems and needs no hydraulics, yet it gives better rotational inertia, which is important for good autorotational characteristics.

The servo flap is extremely simple in concept and execution yet very effective in control. The reasons for its application in helicopter design being limited to exactly one company are rather hard to comprehend, nevertheless should not be attributed to flaws in the system.

http://www.helis.com/howflies/servo.php

joe nelson
10-12-2007, 10:58 AM
I love those servo flaps and work on mine each day...working on the swash plate control system (classic gimbal) today. Had a idea of using uhmw plastic in lieu of the bearings.

quadrirotor
10-17-2007, 05:47 AM
Two interesting videos:

http://www.youtube.com/watch?v=sMV5iy4ARdg

http://www.youtube.com/watch?v=4z7NSr2y6pg

quadrirotor
10-17-2007, 06:28 AM
Advantages of the coaxial set up, explained by Kamov:

http://www.kamov.ru/market/news/petr11.htm

quadrirotor
10-17-2007, 01:45 PM
The rotorcycle:

http://www.youtube.com/v/223lA5Trj3Q

quadrirotor
10-18-2007, 06:43 AM
Do you like it? how much are you willing to pay for it?

http://www.rotor-international.net/start.html

PTKay
10-18-2007, 10:46 AM
This is the answer I got from them:


vielen Dank für Ihr Interesse an unseren Helikoptern. Der Eaglet kostet, je nach Ausstattung des Kits, zwischen 60.000 € und 100.000 €. Die genauen Optionslisten sind in Vorbereitung, wir schicken sie Ihnen gerne zu, wenn sie bereit sind.
Ausgeliefert werden die ersten Kits in der zweiten Jahreshälfte 2008.

Mit den besten Grüßen, / Kind regards,

Christian Frey, CEO


"...thank you for your interest in our helicopters. The Eaglet costs, depending upon equipment of the kit, between 60.000€ and 100,000€. The exact option lists are in preparation, we dispatch them to you gladly, if they are ready. The first kits shall be delivered in the second half of the year 2008."

quadrirotor
10-18-2007, 12:46 PM
Thanks Paul, almost the same price as a Xenon!!! ;)

PTKay
10-18-2007, 12:53 PM
Eaglet is a kit,
Xenon - ready to fly....

Small difference. ;)

quadrirotor
11-03-2007, 08:14 AM
To build from a complete kit, when you have all the peaces and bits, it's a real pleasure!!!

Rotor Rooter
11-04-2007, 11:15 PM
André

At last ~ a helicopter for every garage.


Tatarinov "Aeromobile" ~ 1909
http://www.aviastar.org/foto/tatarinov.jpg

............. and it has 4 rotors.;)


Dave

quadrirotor
11-05-2007, 06:17 AM
Be serious, Dave!...And in the coaxial topic!...
Here you have a new variation of the Sikorsky project which converges to the GYROCOAX, as you could have a vectorizing tail...It seems the vectorizing tail is a solution for simplification!...

Rotor Rooter
11-05-2007, 11:34 AM
Andre, OK but if we are going to get serious I've got to vote against the Coaxial configuration.


For homebuilt rotorcraft; the thrust-to-power ratio is a serious concern, particularly when using 2-stroke engines. The coaxial has a significantly inferior thrust-to-power ratio in comparison to bilateral twin main rotor configurations.


For fast future craft; I suspect that the coaxial, such as Sikorsky's X2 may have a terminal problem. The earlier Sikorsky S-69 ABC was unable to achieve the top speed objective, due to excessive vibration. It had provisions for vibration damping devices but for some reason they never added them.

The following is copied from PPRuNe. It may explain the reason for this problem and an inability for the coaxial configuration to excape it.
"Consider the side of the craft coaxial ABC] where the upper blades are advancing and the lower blades are retreating, during cruise. The use of ABC means that the upper (advancing) blades are providing most of the thrust. The lower (retreating) blades are meeting the airflow with a sharp leading edge.

We know that a sharp leading edge can only operate within a small range of AOA. We also know that there is an amount of time required for the sectors of an airfoil to recover from a stall. In addition, we know that the lower blades on this side of the craft are passing in and out of the thrust of the upper blades 8 times per rotor revolution.

IMHO, it is reasonable to assume that segments of the lower retreating blades will passing in and out of stall, at rates of up to 8 times per RRPM."

The bilateral twin main rotor configurations should not be subjected to this specific concern.


Dave

quadrirotor
11-05-2007, 02:24 PM
Andre, OK but if we are going to get serious I've got to vote against the Coaxial configuration.


For homebuilt rotorcraft; the thrust-to-power ratio is a serious concern, particularly when using 2-stroke engines (not mandatory). The coaxial has a significantly inferior thrust-to-power ratio in comparison to bilateral twin main rotor configurations. For private purposes, at 100 mph, it's not a problem...

For fast future craft (that's out of concern!!!); I suspect that the coaxial, such as Sikorsky's X2 may have a terminal problem (AMEN!). The earlier Sikorsky S-69 ABC was unable to achieve the top speed objective, due to excessive vibration. It had provisions for vibration damping devices but for some reason they never added them.

The following is copied from PPRuNe. It may explain the reason for this problem and an inability for the coaxial configuration to excape it.
"Consider the side of the craft coaxial ABC] where the upper blades are advancing and the lower blades are retreating, during cruise. The use of ABC means that the upper (advancing) blades are providing most of the thrust. The lower (retreating) blades are meeting the airflow with a sharp leading edge.(????)

We know that a sharp leading edge can only operate within a small range of AOA. We also know that there is an amount of time required for the sectors of an airfoil to recover from a stall. In addition, we know that the lower blades on this side of the craft are passing in and out of the thrust of the upper blades 8 times per rotor revolution (FALSE, at cruise, no blade passes in the downwash of the upper blades!!!!).

IMHO, it is reasonable to assume that segments of the lower retreating blades will passing in and out of stall, at rates of up to 8 times per RRPM."

The bilateral twin main rotor configurations should not be subjected to this specific concern.(for homebuilding purposes: too complex, too large, not compact enough, too much dead weight, too much airframe blown during take off, etc...and above all: i don't like side by side rotors, except synchropters...)

Dave

Once again, this forum is mainly peacefull homebuilding oriented, not high speed warrior rotorcraft... You certainly saw the video on the GYRODYNE, this craft with two tandem seats: it's all we need!!!:violin: :der:
The best, of course, would be the ROTORFLY...But a little expensive for the moment!...

karlbamforth
11-05-2007, 04:38 PM
I agree, we should be able to use the Gyrodyne drive and control system on a modern fuselage with two seats. This should be easy to do.

Maybe we should get together to design and build a few. :D

Rotor Rooter
11-05-2007, 07:37 PM
André

Homebuilt coaxial only.
The "high speed warrior rotorcraft" can be discussed; if someone wishes to.


The importance of Power Loading (http://www.unicopter.com/0939.html)

The following sketch, from this web page, (http://www.unicopter.com/B360.html#Required_Power_Comparison) show two extreme configurations, that of the coaxial and the side-by-side. Prouty's calculations show that 50% more horsepower is required to hover a coaxial helicopter than side-by-side helicopter with the same specifications.

http://www.synchrolite.com/Configurations.gif

There are two basic solutions to overcome this difference;

Install a much larger engine, power-train and rotors etc. in the coaxial. However, this will add even more weight, which in turn requires an even large engine, power-train and rotors etc. 50% more.
Use a very light and less reliable engine and power-train etc. in the coaxial. However, this will involve risk.
How much risk does a person want to take?
~ the Robinson uses a 4-stroke Lycoming engine, which is then derated.
~ the Original Helicycle and the Mini-500 used 2-stroke Rotax engines, which were then given tuned exhausts to extract more power out of these lightweight engines.


You mentioned; too complex, too large, not compact enough, too much dead weight, too much airframe blown during take off, etc.A side-by-side helicopter with an empty weight that is nearly half that of a comparable coaxial means that many of your concerns are, or can easily be, eliminated.


Dave

Bruno
11-06-2007, 01:05 AM
Has anyone flown a side-by-side two-rotor gyro?

quadrirotor
11-06-2007, 04:34 AM
Sorry Dave, this thread deals with homebuilt coaxial helicopters...I opened this thread for you:
http://www.rotaryforum.com/forum/showthread.php?t=14667

You could expose the advantages of the side-by-side rotors...
Most of the time you bring complications, never simplications or a technological solution...

Many people seems aside of their shoes!... But, I think that most of the time, they are dysinformation agents!...

That's what we need, with a pretty aerodynamic shape! The Wagner Skytrac or the GYROCOAX!...

Rotor Rooter
11-06-2007, 10:49 AM
André Sorry Dave, this thread deals with homebuilt coaxial helicopters I believe that my remarks and information are directed at the coaxial configuration. They are not the promotion of any specific configuration.

My 'mode de opération' is to look for the technical shortcomings of ALL configurations and be aware of them early, at at the stage of the 'notepad' not the 'helipad'.


Dave

quadrirotor
11-06-2007, 12:32 PM
It's only a scaled up of the GYRODYNE:

karlbamforth
11-06-2007, 04:44 PM
Looks great to me when do we start building ?

quadrirotor
11-07-2007, 04:10 AM
Where is Oxford? GB?

quadrirotor
12-10-2007, 07:15 AM
always amazing!!!

http://www.dailymotion.com/search/h%C3%A9licopt%C3%A8re/video/x3pj1w_helicoptere-personnel_extreme

Bruno
12-10-2007, 07:31 AM
Yes, an amazing device built by a certain Dr. Schoffmann of Germany. (Hope I have not misspelled his name.) He rarely manages to get out of ground effect, but I do find it amazing that his device flies at all.

Here's a picture.

Sita
12-10-2007, 09:53 AM
"out of ground effect" is roughly 1 1/2 times rotor diameter.With only 2.13 meters diameter,Mr. Schöffman flies regularly out of ground effect.
I have seen him reaching a height of about 10 meters last year in Wels (Austria).


Cita

Bruno
12-10-2007, 09:59 AM
"out of ground effect" is roughly 1 1/2 times rotor diameter.With only 2.13 meters diameter,Mr. Schöffman flies regularly out of ground effect.
I have seen him reaching a height of about 10 meters last year in Wels (Austria).


Cita

Cita, I respect you because of your impressive background, and do not mean to contradict you. However, all the photos and videos I have seen show Mr. Schöffman hovering just a few feet above ground -- less than his own body height. Do you have better pictures or videos?

Sita
12-10-2007, 01:09 PM
Bruno,

Thanks for the flowers!:D

"Herr Schöffman" would be flying "out of ground effect" theoretically speaking when his feet would be roughly 1.2 m above the ground.
Even this short clip shows Mr. Schöffman a few times higher than this.
I agree though that even the 30+ hp he's using seems marginal with the extreme small rotor diameter and I guess that the 10m altitude I saw last year is probably the best he can do under near perfect conditions.
I had the chance to examine his little helo and the simplicity in both design and construction is beyond believe.
Although very sencitive (spelling?) I'm surprised at how well he's able to control the craft,after all 2.13 m diameter is VERY small,even for a UL helo.

Cita

Bruno
12-10-2007, 03:11 PM
Bruno,

Thanks for the flowers!:D

"Herr Schöffman" would be flying "out of ground effect" theoretically speaking when his feet would be roughly 1.2 m above the ground.
Even this short clip shows Mr. Schöffman a few times higher than this.
I agree though that even the 30+ hp he's using seems marginal with the extreme small rotor diameter and I guess that the 10m altitude I saw last year is probably the best he can do under near perfect conditions.
I had the chance to examine his little helo and the simplicity in both design and construction is beyond believe.
Although very sencitive (spelling?) I'm surprised at how well he's able to control the craft,after all 2.13 m diameter is VERY small,even for a UL helo.

Cita

Having observed it at close range, do you think it could be improved to a notable degree?

quadrirotor
12-11-2007, 12:06 PM
The gear boxe which could be scaled up easyly!!!

quadrirotor
12-11-2007, 12:10 PM
Even if for the Nolan coax, the set up is a bit more complex (uselessly), it's easier to manage a collective through the precedent set up!!!

http://www.google.com/patents?id=tRQcAAAAEBAJ&printsec=abstract&zoom=4&dq=nolan+helicopter

PTKay
12-20-2007, 06:30 AM
recent news, I received from them:

"Dear Customers,

the end of this year has come and we would like to thank you for your interest in our helicopters. A lot has happen this year - the setup of the Stendal workshops, launch of the new website, the presentation in August, the exhibitions in November and December - just to mention a few. In the moment we are very busy to test the new autopilot, which will be available as an option for the RI 30, and to assemble the second generation of prototypes of the Eaglet. Development on the RI 600 is ongoing - we plan to do the first flight as soon as possible.

From spring next year on, we will be happy to offer test flights to you. The precise dates will be spread via our website and this mailing list - or simply drop a call or mail, if you have any questions or wishes regarding that. We will be happy to welcome you in Stendal and are looking forward to meet you in person!

Meanwhile we have begun to take orders. Do not hesitate to place yours - we will be happy to help you with that when our office opens again on 2nd January.


With the best wishes from Russia and Germany,

the ROTOR International Crew"

quadrirotor
03-03-2008, 05:40 AM
Nolan coaxial in flight!


https://www.youtube.com/watch?v=0QHfBucsL0Q

quadrirotor
04-12-2008, 06:44 AM
RI300 in flight, details of the setup:

http://www.youtube.com/watch?v=OcwD953QCYA

lgcs3110
05-03-2008, 07:51 PM
They are definitily coming...

http://wielandhelitech.com
http://www.youtube.com/watch?v=TGe-vePJzzs&feature=user
http://www.aviodyne.com/ROTORCYCLE.html
http://www.rotor-international.net

Gustavo

cmo111
05-16-2008, 06:26 PM
Hi team

A member here from downunder in New Zealand.

Our team are researching coaxial systems and have come across:

1. Ezycopter Taiwan Dr C Lin.

2. RI 30 Eaglet (courtesy your site).

3. Wieland Australia.

Photo of ours below.

Can any members give us information on merits of the three systems above please.

Thanks

chris :rapture:

quadrirotor
05-17-2008, 07:08 AM
Just for information, the mating of a GYRODYNE and a ENSTRÖM helicos:

Brent_Brown
05-17-2008, 01:15 PM
Chris What ever that is in the photo is very nice. What is it? tell us all about it.

quadrirotor
05-17-2008, 01:31 PM
Eh! Dennis Fetters! can you make this one with the same set up as the RI30?

http://www.rotaryforum.com/forum/attachment.php?attachmentid=26324&stc=1&thumb=1&d=1159459301

cmo111
05-17-2008, 03:46 PM
Hi Brent

This is our compound helicopter being built and tested in New Zealand at Ardmore Aerodrome by our company. We are already using rotary engines successfully and hope to put a coaxial rotor on top - in the testing stage we are using a simple gyrocopter rotor.

Note this is not simply a mockup - its a working aircraft.

Thanks for the compliment

chris

:wave:

yolandbeaudet
05-19-2008, 10:37 AM
Does anyone know how the RI 30 Eaglet achive yaw control ?

and how would you compare there technology (teetering rotor)
to the more traditional of the gyrodyne use by Wieland Helicopter?

for manoeuvrability(handling) , complexity, reliability, maintenance ect.

quadrirotor
05-21-2008, 08:30 AM
Hi Chris, one of most interesting project since a long time!...
It is needed more info on the dynamic parts of this compound, which could be compared to the gyrocoax...
Seems to be too small to lodge all the gears for the added coaxial set up but i am eager to see more on this!!! :)

quadrirotor
06-01-2008, 12:11 PM
An other variation of the Sikorsky X2, with its rough imitation: the Barnett gyro with the airscooter set up!

Rotor Rooter
06-01-2008, 02:20 PM
André

Some support for your idea.

Hiller XH-44 ~ 1944 (http://www.aviastar.org/helicopters_eng/hiller_xh-44.php)

Hiller X-2-235 ~ 1945 (http://www.aviastar.org/helicopters_eng/hiller_x-2-235.php)

One of three prototypes of the 2-seat Hiller UH-4 Commuter ~ 1946. (http://www.fsdome.com/aviation-encyclopedia/helis/country/usa/helis/79.htm)


Nick Lappos has mentioned that a wind tunnel test of Hiller's craft with its extremely rigid two-bladed rotors did damage to wind tunnel. This was due to the vibration produced by applying cyclic to extremely rigid rotors with only two blades each.

The pictures in this report look like Hiller's extremely rigid rotors
NACA ~ FULL-SCALE-TUNNEL INVESTIGATION OF THE STATIC-THRUST PERFORMANCE OF A COAXIAL HELICOPTER ROTOR By Robert D. Harrington (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930083001_1993083001.pdf)

Note that at the bottom of the above X-2-235 page it says
"As a result of the NACA tests, Hiller initiated redesign of the X-2-235 to incorporate three-bladed coaxial rotors .............................."

You may wish to consider that the use of the extremely rigid three-bladed rotors should provide very fast control response, plus eliminate the complexity of lead/lag or teetering hinges.

Dave

quadrirotor
06-01-2008, 02:29 PM
That's two (semi-rigid) gyro rotors as the Airscooter' ones! Sized as needed, of course!...and being autorotation-able, too...
The RI300 has semi-rigid rotors too, but with variable pitch...

PTKay
06-02-2008, 02:26 AM
"As a result of the NACA tests, Hiller initiated redesign of the X-2-235 to incorporate three-bladed coaxial rotors augmented by an aft-thrusting rear propeller. The reworked craft was obviously geared to flight at speeds substantially higher than those attained by existing helicopters."

Do I miss something?

It's X-2 by Hiller in the forties, or X2 by Sikorski in 2008...

They needed 60 years to find out ???

quadrirotor
06-09-2008, 07:38 AM
From the Prouty's papers:

Rotor Rooter
06-10-2008, 11:29 AM
André

The following is a technical paper that has your sketch.

A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research. (http://www.humanpoweredhelicopters.org/articles/nasa-tp-3675.pdf)

____________________________________


A sketch of the disk areas and hovering thrust distributions of various configurations.

http://www.unicopter.com/0949.gif

quadrirotor
08-09-2008, 07:45 AM
Just an other alternative for the Gyrocoax:

quadrirotor
08-21-2008, 08:31 AM
Coaxial helicopters with fixed pitch.

Just for references, video of:
NOLAN in flight:
http://www.youtube.com/watch?v=0QHfBucsL0Q

AIRSCOOTER:
http://www.youtube.com/watch?v=E-3beBkHMcg

GEN-H4:
http://www.youtube.com/watch?v=MyWxaiPQ7JY&feature=related

ULTRA-LIGHT:
http://au.youtube.com/watch?v=xPA2k3qPe-4

quadrirotor
08-28-2008, 08:39 AM
X2 technology helicopter flew yesterday:

http://www.sikorsky.com/sik/about_sikorsky/news/2008/20080827_1.asp

PTKay
08-28-2008, 09:08 AM
The NOLAN Eagle's Perch helicopter mentioned 2 posts above
and seen on youtube was designed and manufactured
by the same people who work niow on the X2.

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

See the list of companies involved in the press release:
the Eagle Aviation Technologies, Inc., who made main rotor blades,
and miscellaneous composite hardware
origins from Nolan brothers workshop in Virginia...

World is small.

And the rigid rotor coaxial idea lives on.

:first:

Does it remind you of something ???

http://www.eagleaviationtech.com/Eagle%20Aviation%20Technologies,%20Inc%20UAV.pdf

;)

quadrirotor
08-28-2008, 11:02 AM
The NOLAN Eagle's Perch helicopter mentioned 2 posts above
and seen on youtube was designed and manufactured
by the same people who work niow on the X2.

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

See the list of companies involved in the press release:
the Eagle Aviation Technologies, Inc., who made main rotor blades,
and miscellaneous composite hardware
origins from Nolan brothers workshop in Virginia...

World is small.

And the rigid rotor coaxial idea lives on.

:first:

Does it remind you of something ???

http://www.eagleaviationtech.com/Eagle%20Aviation%20Technologies,%20Inc%20UAV.pdf

;)

Yes the Nolan Brothers are very present:
From the list of personnel of the AIRSCOOTER Comp.
"Jack and Herb Nolan serve as technical, test flight and training consultants to AirScooter. They used their racing background to develop small helicopter designs in the 1980s and have valuable practical flight experience."

The next step is the GYROCOAX which enables the autorotation!... ;)

PTKay
08-28-2008, 11:45 AM
The next step is the GYROCOAX which enables the autorotation!... ;)

Sorry, Andre, but I would disagree.

There is no reason to unnecessarily complicate an autorotating device,
like a gyrocopter, with a double, coaxial rotor....

;)

Coaxial dual rotor against power wasting tail rotor: YES
Coaxial dual rotor against nothing (in a gyrocopter): NO

quadrirotor
08-29-2008, 05:16 AM
A double coaxial rotor can be motorized more efficiently in flight without the reaction torque, enhancing the EFFICIENCY and the SAFETY (the two main issues of the gyro).
Enables a very very short take off and landing, with the use of the powerfull "prerotator", almost an helicopter behaviour without the blades pitching problem or the tail rotor behaviour; yet enabling autorotation, as you have gyro (smaller) rotors...!
Less demanding than a jump take off gyro (see the Dick Degraw's stunts!)...

I don't think the construction would be more complex (see the photos):
-less complex to make than a coaxial helicopter (fixed pitch blades).
-as complex as a gyrocopter (as you need a good prerotator, anyway).

quadrirotor
09-10-2008, 09:38 AM
Do you think it is very difficult to replicate it today, sixty years later???:ohwell:
The Kamov Ka10 1949:


http://au.youtube.com/watch?v=H6haCY3tpFQ

PTKay
09-10-2008, 01:39 PM
-less complex to make than a coaxial helicopter (fixed pitch blades).
-as complex as a gyrocopter (as you need a good prerotator, anyway).

But how are you going to realize the prerotation of the couterrotaing blades ??
You need a complex system of gears like Eagle Perch (Nolan) or AirScooter.

When you have this, why the pusher prop on top of it ?

You already have a helicopter... kind of...

:)

quadrirotor
09-10-2008, 03:26 PM
The angle of incidence (pitch) of the blades, of a fixed pitch helo, is set to an angle which can not allow the autorotation (4°aerodynamic for autorotation, ~8°-10° for f.p. helo and for a better helo efficiency). The Nolan or the Airscooter can not autorotate!...

If you want to enable autorotation, you set the pitch of the blades at 4°, but so you can not take off at a reasonable powered RRPM!...So you need to translate and use the pitch of the entire rotors as a means to increase the pitch of the blades (as with a gyro)...So you need a pusher engine (as with a gyro)... But the efficiency of the so-called GYROCOAX will be amazing, as you have always your rotors "powered" beyond the autorotation RRPM, with rotors almost horizontal!...And without the reaction torque...And without the fear to lose the autorotation, sometime, somewhere... (the autorotation is taken too much for granted!!!)... And so on... :)

You have an exemple of what could be a GYROCOAX, posts #49, #73, #79.

quadrirotor
10-10-2008, 06:58 AM
Post#80:
>>>>>>>>>>>>>>>
Coaxial helicopters with fixed pitch.

Just for references, video of:
NOLAN in flight:
http://www.youtube.com/watch?v=0QHfBucsL0Q

AIRSCOOTER:
http://www.youtube.com/watch?v=E-3beBkHMcg

GEN-H4:
http://www.youtube.com/watch?v=MyWxa...eature=related

ULTRA-LIGHT:
http://au.youtube.com/watch?v=xPA2k3qPe-4

<<<<<<<<<<<<<<<<<<<<<<


Something similar to those of post#80 but with a collective on each rotor:

http://www.rotaryforum.com/forum/showthread.php?t=18431

Rotor Rooter
10-10-2008, 10:33 AM
What about incorporating an automatic pitch-change mechanism?

It would provide advantages for partially and fully powered rotors, plus for propulsors.

There is a lot of material available on the subject. It has been done in the past. It would make for an interesting thread.

It might even make for an interesting group of low cost automatic-pitch projects. A type of Wikinomics (http://en.wikipedia.org/wiki/Wikinomics) by interested forum members to participate in one or more of the steps; requirements, conceptualizations, designing, calculations and prototyping.


Dave

quadrirotor
10-10-2008, 11:11 AM
What about incorporating an automatic pitch-change mechanism?

It would provide advantages for partially and fully powered rotors, plus for propulsors.

There is a lot of material available on the subject. It has been done in the past. It would make for an interesting thread.

It might even make for an interesting group of low cost automatic-pitch projects. A type of Wikinomics (http://en.wikipedia.org/wiki/Wikinomics) by interested forum members to participate in one or more of the steps; requirements, conceptualizations, designing, calculations and prototyping.


Dave

Yes, for a gyro, an automatic pitch actuator can be made like the one of a french gyro, and it works:

http://www.rotaryforum.com/forum/showthread.php?p=79969#post79969

But for the ULTRALITECOAX, i thought about it and i concluded that it is simpler to have the two (brain) manual-actuated variable collectives. And above all, i don't see anything simpler which could give more pitch at high power setting, and more pitch at low speed and low altitude (just before landing) if the engine quits!...And enabling also to give less pitch if the engine quits at high altitude, during autorotation!...

For the WIKINOMICS, it seems there is not many people interested in this kind of collaboration... :(

Rotor Rooter
10-10-2008, 12:13 PM
Andre,

Gyrocopter:
My knowledge of the gyrocopter is very limited (and it may not be much better for the helicopter :o) However, I believe that the basic gyrocopter has automatic rotor speed control due to the aerodynamics of autorotation.

The addition of manual or automatic pitch-control is only required on a gyrocopter when jump-takeoff or a partial-powered-rotor is incorporated. Perhaps there is little interest in the community to add these two features to gyrocopters. Perhaps the cost, complexity and minimal benefits are the reasons.

Helicopter:
IMHO, if there is a desire to have a simple, cheap, safe and reliable helicopter 'in every garage' then the piloting difficulty and craft maintenance must be significantly reduced. Whereas current recreational helicopter pilots appreciate the challenges of mastering the skills and maintaining the craft.

An analogy would be the bicycle vs the unicycle.

One idea toward putting a rotorcraft in every garage:
I believe (hope) that torque-pitch and speed-pitch can both be built into a 1-piece hub-bar. This would be achieved by producing the hub-bar out of carbon and fiberglass tow instead of an aluminum plate. The objective is to have torque and centrifugal force (coning angle) effect the pitch of the blades.
One current project; http://www.unicopter.com/0575.html

Dave

quadrirotor
10-11-2008, 08:24 AM
Gyro: variable pitch could be desirable in case of low G: the rotor governor, by lowering the pitch, enables the rotor not to slow down to much, and to regain speed more easyly with the coming back G...Then, the gyro gaining speed, the pitch of the blades will be higher as the speed of the rotor gains speed also, so the rotor will tilt forwards, giving more efficiency to the system!...

Helico: In this case, i don't like automatic things which can not be disconnected at once!!! The coaxial helico is very simple to pilot as there is no tail rotor! A journalist took one hour to learn to fly the AIRSCOOTER, alone!!! For the ULTRALITECOAX, the only problem which could remain is the correllation between the collective and the power requirements: a governor must to be used! this governor (as for the MOSQUITO) is a full electric car cruise control (with a lot of settings by micro switches: sensibilty, gain, etc...) which is used in the Hot Rod domain, and can regulate the engine RPM...cost: $250!!!

The problem of the ULTRALITECOAX is not a problem of feasability, but a problem of manufacturing!!! I have no means to make and gather all the pieces and bits, to make this coax a serviceable helico!...

quadrirotor
10-22-2008, 07:24 AM
Have someone more info on the VIKI coaxial helicopter?

http://www.rotaryforum.com/forum/attachment.php?attachmentid=46675&d=1211033278

quadrirotor
10-22-2008, 08:01 AM
Has anybody more infos on this one? is it on the market? etc...:

http://www.rotor-international.net/helicopter/ri-30-eaglet/gallery-eaglet.html

tyc
10-23-2008, 07:14 AM
Just came across your postings ...

That VIKI machine, I wonder why they didn't invert the powerplant.

As for that second one, by chance, isn't that the VIKI machine?

tyc

Sita
10-27-2008, 04:46 AM
Just came across your postings ...

That VIKI machine, I wonder why they didn't invert the powerplant.

As for that second one, by chance, isn't that the VIKI machine?

tyc


Tyc,

I think the rotor system in the latter differs from the VIKI as is the engine placement and the tail I guess.

It could be though that the second helicopter is a developped prototype from the proposed VIKI drawing.

Inverting an engine which is not designed to operate in that "new mode" can be a very tricky thing and I know from first hand information that Rotax for example will not permitt use from their engines in manned craft,other than the postion to operate in they are designed for.

Cita

Doug Schwochert
12-05-2008, 07:29 AM
Just so happens I have a picture of this very helicopter I'll post it (I hope)
http://i273.photobucket.com/albums/jj221/schwoch1/dustin2.jpg

Doug S

quadrirotor
12-05-2008, 10:33 AM
Thanks Doug. Have you any info on this one? location? is she flying? what about this helico?

karlbamforth
12-05-2008, 07:46 PM
Hahahaha at first glance I thought it had a blue tail rotor with yellow tips.

Then I saw it was a ladder... I need new glasses.

Looks real nice, did it ever fly ?

A company in Australia is building something like this, I believe got orders from Thailand, singapore etc.

quadrirotor
12-15-2008, 11:16 AM
News from EASYCOPTER!

http://www.ezycopter.biz

joe nelson
01-01-2009, 04:12 AM
I have to plead my igorance on rotor tip brakes. Looking at the pictures of the small coax helos I see the tip brake...how do they work?

Arnie Madsen
01-01-2009, 05:40 AM
I have to plead my igorance on rotor tip brakes. Looking at the pictures of the small coax helos I see the tip brake...how do they work?


Good morning Joe.

From memory in one of my old helicopter design and data manuals (by Stanley Dzik ) he showed a tip brake drawing.

I think it was used on the Hiller Rotorcycle one man co-axial developed for the Army. In order to control yaw each set of blades had small flap on the end to create drag. The 1" square flap simply folded out into the airstream at the rotor tip.

It used a small rod down the length of the inner blade to control the small flap . Each set of blades had these flaps and the controls were almost like an additional swashplate in amongst all the other linkages (complicated)

They were connected to the rudder pedals. The idea was to create more drag on one set of the (co-axial) blades by opening the flaps into the airstream and the extra drag caused the fuselage to rotate. Opposite pedal and flaps opening on the other blades to rotate the other way.

In other words , the torque free co-axial rotor now required more torque on one set of blades than the other and the fuselage would have rotate. Hope that makes sense.

Some experimenters use a small brake band at the hub of each rotor to do the same thing. Mostly they were trying to eliminate an actual rudder in the downwash behind the helicopter for yaw control.

Some experimenters use a system to apply slightly more collective to one set of blades than the other which also works.

C0-axial blades and controls are complicated enough , and with the added yaw control it gets even worse. For this reason most designers see the single rotor helicopter with a tail rotor a much simpler solution .

Even if you look at the production Kaman Husky , they had to use a huge ungainly set of downwash rudders at the rear for yaw control. All this to eliminate a small tail rotor. Not very practical in the end.

Happy new year Joe.

Arnie

ps: I am glad you saw the strap pack on the Ukrainian built helicopter I posted elsewhere. I was thinking of you when I saw it. It sure would be nice to have a machine shop like those guys .....

brett s
01-01-2009, 05:41 AM
They add more drag when extended, then the basic rules of physics apply - if one rotor has more drag than the other, you'll yaw.

C. Beaty
01-01-2009, 07:37 AM
Traditionally, yaw has been controlled by differential collective pitch in coaxial helicopters. The problem then is that yaw pedals reverse in autorotation unless some type of automatic linkage is introduced to prevent reversal. Syncopters have the same problem. Dick DeGraw has pedal reversing linkage coupled to collective pitch on his syncopter. .

Tip brakes do not reverse yaw direction.

The Nolan Bros. helicopter had fixed collective pitch with blades ground adjusted for torque balance; in-flight yaw being controlled by a canted rudder in the rotor downwash. The lower rotor needs more collective than the top rotor for torque balance.

Bensen interposed a differential between engine and rotors, eliminating airframe torque reaction altogether. He also used canted rudders or on at least one occasion, a chain saw engine and torque rotor mounted on the tail.

Rotor Rooter
01-01-2009, 09:27 AM
Joe,

If you want pictures, there are some good ones on http://www.gyrodynehelicopters.com/xron_history.htm

Cikatti
01-02-2009, 04:10 PM
"Have someone more info on the VIKI coaxial helicopter?"

Hello, VIKI was my uncle and he died about 9 years ago, he got his first heart attack... he was just finalizing this amazing "machine" which has inverted Allison (can´t remember was it 18 or 20). Fuselage is from Enstrom 28.

He painted this copter green as it can be seen on post #98. BTW where this picture has been taken? Who owns this nowadays?!

This copter has got Hughes 500 avionics, hydraulic controlled cyclic column.
My uncle had hughes 500 C earlier and also Bell 47 G before Hughes.

I remember how he purchased this Gyrodyne coaxial mast about 1998 from US and I think it was even never used earlier. It was kind of finding from NAVY surplus storage.

As uncle died, just before he was actually to able to start this copter. He had only one daughter... must say that embaressing, I haven´t been discussing with her for several years. I never asked later what she did to this copter, just due to simple reason. I´ve been really sad and disapointed how he died so early.

Where is this copter and is it flying? I definitely want to come and see this copter. I´m so confused to this green beauty in here.

quadrirotor
01-03-2009, 05:25 AM
Thanks, it would be a pity if this copter becomes a scrap!
Would be very glad to hear more from you!
Thanks again. :)

Doug Schwochert
01-03-2009, 06:43 AM
Hi all

I think This helicopter is now in Utah somewheres near Salt lake city or within a couple hours of there.The person that owns it bought rotor blade extrusions from me. we got talking I mentioned that I would be in salt lake city doing a Helicycle checkout. he asked ir he could come and visit while I was there.
I am pretty sure he has the helicopter in his posession. He must have it he e mailed me pictures of him standing with it. He told me the particulars on it but that was over 2 years ago and with my good memory I cant remember them. I do not rememer his name but I will try and dig up the pictures that I have maybe that will give me a clue who he is. I'll post the other pictures later. I assume he has the helicopter, either that or he is building one.

Doug

valotus
01-04-2009, 05:21 AM
Hello all,

Thanks to Cikatti, I found this forum and saw this very familiar copter project for a long time. Concerning that, I'll try to find some images from my archive though there may only be some technical shots of different parts.

Anyway, I knew Viki for ten years before he died; I did my first aerial photoshootings from his 500C in 1988. After that we met quite often because he lived near me and we both had same technically orientated hobby, Citroen cars... :)

Cikatti may be the best to tell more of Viki's background, but said shortly, Viki was one of the first copter mechanics in Finland and had long career in Frontier Guard and Finnish Air Force before started his own business as helicopter operator. He was extremely talented and nice person.

I would also be very interested to see this coaxial project again as it was so close to be ready...

J-P

joe nelson
01-04-2009, 06:11 AM
Arnie, Chuck, Dave, Andre and Brett,

Thanks for the information! I'd seen tip brakes before but never thought the complexities of their use. Being a fan of the Kaman system, I did notice the vertical stabs tilting right and left but again never thought of the yaw issues.

The Nolan aircraft was very interesting as well. My interest was how they handled the power transmission...two 503's through a single light system...neat! I did hear early on of it's inablity to autorotate but I never knew why.

joe nelson
01-04-2009, 06:26 AM
Arnie,

I love the Hughes strap pack system! Now that I've found a source for .oo9" stainless I can start experimenting with the concept. My servo flap experimentation is progressing but slowly. I've changed the airfoil for the flap from an 8H12 to a symetrical one because of my concern with its pressure changes. Where has been no dynamic tests as of yet but it's coming soon!

joe nelson
01-07-2009, 12:01 PM
Does the Kamovs use tip brakes or just swash plates for each rotor set? I have a couple of small pictures of a Ka-32 and Ka-50 which appear swash plate controlled. Both have large vertical stabs but only the Ka-50's seems to be conventional. The Ka-32's stabs tilt both like a rudder and elevator.

Rotor Rooter
01-07-2009, 12:20 PM
Joe,

Kamov Yaw Control (http://www.unicopter.com/1119.html#Yaw)

Dave

joe nelson
01-09-2009, 01:44 PM
Dave,

Does the Kaman aircraft have the same yaw characteristics?

Doug Schwochert
01-09-2009, 02:09 PM
Hi all


The persons name Is Dustin Hartley I could not find out where he lives. All I know it was driving distance to Salt Lake city. I'll keep looking


Doug

Rotor Rooter
01-09-2009, 06:54 PM
Joe,

You will find Yaw Control information near the top of both these pages.

Intermeshing - Kaman - H-43 Huskie (http://www.unicopter.com/0742.html)

Intermeshing - Kaman - K-MAX (http://www.unicopter.com/0473.html)

Dave

joe nelson
01-13-2009, 08:02 AM
Dave,

Thanks for the information! After reading each article I understand the yaw reversal in the coaxial rotor system and the collective fade on synchrocopter. I'm still having some difficultly with the causitive dynamics in yaw reversal and pitch instability in the synchrocopter. Is it a reverse of air flow between the rotors as in the coaxial?

I've been experimenting with a Kaman style rotor for about two years. My version is more toward the system as on the seasprite than the husky. The rotor system that I'm working with will always fly in autorotation so I'm not expecting to encounter these characteristics but it's always good to be aware of all possibilities.

Rotor Rooter
01-13-2009, 09:46 AM
joe.

The Coaxial helicopters controls yaw by increasing the collective pitch on one rotor and reducing it on the other. This results in the combined thrust of the two rotor being unchanged. However, the drag of the two rotors is different and this causes the craft to yaw.

During autorotation the craft will yaw in the opposite direction. Therefore the pilot must use the other pedal, or the craft's mixer box must have a means of automatically switching the pedal linkages. The automatic switching is done by the position of the collective lever.


The Intermeshing helicopter controls yaw the same way as the coaxial, but it also uses opposed longitudinal cyclic.


The rotor system that I'm working with will always fly in autorotation ..... If the craft is always flying in autorotation (gyrocopter), why are you thinking of using 2 rotors?


Dave

joe nelson
01-13-2009, 10:47 AM
Dave,

I have been trying to build a gyro that is the Cessna 172 of gyros for a long time but I have found it is as easy to build a helo.

I have built a model tandem gyro and have had a lot of fun experimenting with it until a piece of plywood fell on it last summer. If large loads are to be carried by this type of aircraft, it will likely be a tandem or synchro type of machine.

There are many things to work out before a man-carrying aircraft could be built. I love a good challenge lol.

GyroDoug
01-13-2009, 01:15 PM
Hi all
The persons name Is Dustin Hartley I could not find out where he lives. All I know it was driving distance to Salt Lake city. I'll keep looking
Doug

Doug,

I would love to get any information on this guy that you can find and we will invite him to join our PRA chapter. I did a quick search on Dex knows and couldn't come up with a phone number attached to that name . But if you can find me any other information I will continue to try to find him. Any guy that owns an aircraft like that has got to be a very interesting person and he would be a great asset to our group. Let me know what you find.

Gyro Doug

Cikatti
01-15-2009, 02:40 AM
Hi all


The persons name Is Dustin Hartley I could not find out where he lives. All I know it was driving distance to Salt Lake city. I'll keep looking


Doug

Thanks Doug!
This is good start! Thnks a lot about your help. I wouldreally like see this green devil in the air.

Monk
01-19-2009, 09:22 AM
One of these guys could be Dustin Hartley.

http://www.zabasearch.com/query1_zaba.php?sname=DUSTIN%20HARTLEY&state=UT&ref=&se=&doby=&city=&name_style=1&tm=&tmr=

Doug Schwochert
02-04-2009, 05:44 AM
Hi All

I was in South africa for the last 2 weeks working on 4 Helicycle Helicopters when I opened up my checkout manual, there it was Dustins telephone number. it is about 3 years old. try it and see what happens

208 852 2636 Dustin



Doug

Monk
02-07-2009, 08:32 AM
Hi All

I was in South africa for the last 2 weeks working on 4 Helicycle Helicopters when I opened up my checkout manual, there it was Dustins telephone number. it is about 3 years old. try it and see what happens

208 852 2636 Dustin



Doug

That must have been an interesting trip Doug. Are all four that you worked on completed and flying now? Are all four of them turbines? BJ was a big contributor to the homebuilt heli community.

I have been kicking an idea around in my head and thought of you and John Uptigrove. If you two put your abilities together, I think yuo two could come up with a tandem design for the Helicycle not unlike the Kompress.

Cikatti
02-27-2009, 02:57 AM
Thanks about hints Gentlemen!
This phone number is then to States. I try that!

Cheers

HobbyCAD
03-05-2009, 12:29 PM
These guy's make the co-axial heli's look so easy. The rotors are not so far apart as the EzyCopter, or Kamov types. They seem fairly stable, not shaking themselves to bits. I'm being very tempted to check this type of heli out a bit more. I've always just casually shrugged off the idea of going co-axial, but it seems very successfull in small versions, judging by these video's.

http://www.youtube.com/watch?v=usycKA64jS0

http://www.youtube.com/watch?v=0QHfBucsL0Q

..and they have even gone electric !!

http://www.gather.com/viewArticle.jsp?articleId=281474977472381

Regards,

Francois

Rotor Rooter
03-05-2009, 02:05 PM
These guy's make the co-axial heli's look so easy. The rotors are not so far apart as the EzyCopter, or Kamov types. They seem fairly stable, not shaking themselves to bits. I'm being very tempted to check this type of heli out a bit more. I've always just casually shrugged off the idea of going co-axial, but it seems very successfull in small versions, judging by these video's.


http://www.unicopter.com/ThumbsUp.gif http://www.unicopter.com/Clap.gif http://www.unicopter.com/Clap.gif http://www.unicopter.com/Clap.gif

http://www.unicopter.com/Group.gif . This might lead to this. http://www.unicopter.com/HelicopterSmiley.gif. . . . . . . . . . . . . . http://www.unicopter.com/HelicopterSmiley.gif. . . . . . . . . . . . . . http://www.unicopter.com/HelicopterSmiley.gif

quadrirotor
03-14-2009, 08:04 AM
Kamov KA26
New:
HA-MCB berepülés - YouTube (http://www.youtube.com/watch?v=CDjbn72hNk0&feature=related)

quadrirotor
10-06-2009, 09:00 AM
An other "NOLAN type" helico:

http://www.youtube.com/watch?v=bWyK5YIqDWE&hl=fr

Gyro_Kai
10-06-2009, 10:45 AM
I like this one:

http://www.youtube.com/watch?v=4RITbQHLLhU

Kai.

Lspav8r
10-06-2009, 10:49 AM
E flight uses two motors, one on each rotor and they are electric. Control to the rotors is by adjusting the motor speed to each rotor. the problem with this type of setup as I see it is that you can not really gain much forward speed since the machines are overly stable to the point that you can not overcome any wind at all. check it out. You can buy the flying RC model for less than 100.00 and you can have a lot of fun in the process.

Rotor Rooter
10-06-2009, 12:02 PM
E flight uses two motors, one on each rotor and they are electric. Here is a neat arrangement for a large model. The front motor has a hollow shaft.

http://www.modelmotors.cz/index.php?page=61&product=5330D&serie=20&line=GOLD

quadrirotor
10-10-2009, 07:17 AM
http://en.wikipedia.org/wiki/Lib%C3%A9lula_espa%C3%B1ola

HobbyCAD
10-24-2009, 08:50 PM
Check this out, from New Inventors on Ozzie TV:

To watch the video, go to http://www.abc.net.au/tv/newinventors/specials/# , under the Transport tab, scroll down to Co-axial Rotor helicopter.

Technological advances and a lot of research and development have allowed the Wieland Helicopter Company to build a coaxial counter rotating helicopter that is competitive in the civilian market. Running costs, particularly with the electric motor version, are significantly lower than traditional helicopters.

Since the WHT range of helicopters are much easier to control and to fly, pilot training is much simpler and therefore takes a lot less time and money to complete.

The electric version of the helicopter will be powered by batteries that run an electric motor to turn the co-axial rotors

CONTACTS
Email: sean@wielandhelicopters.com.au
Website: http://www.wielandhelitech.com

Sita
10-25-2009, 12:28 AM
The video is only visible from within Australia

quadrirotor
10-08-2010, 02:37 PM
Speak, and speak of it! Ideas make their way through the mind...

http://www.ezycopter.biz/latestnews.htm

Rotor Rooter
10-08-2010, 04:06 PM
Hi André.

Are you suggesting that the tail rotor is dying? :D


Dave

brett s
10-08-2010, 04:16 PM
The AVX helicopters actually have two tail rotors - the ducted fans aren't just for fwd thrust.

hillberg
10-08-2010, 04:59 PM
Weiland is a single reworked QH-50 :twitch:and the tooling and spares were sold 15 years back:eek:.What weiland can do is in question:rant:.......

hillberg
10-08-2010, 05:01 PM
:twitch:AVX ?:rant: Bell won't share the spoiles of any contract.

Rotor Rooter
10-08-2010, 05:15 PM
Brett.

True the ducted fans are for yaw control as well as forward thrust, but I would not consider them as tail rotors in the conventional sense. In fact the Eurocopter's new X3 is very similar to the AVX except that its propulsors must also counteract the torque of its single rotor.

Heck they both are repeats of the FL-185 by Flettner, who IMHO was the preeminent designer of helicopters.

YouTube - Sikorsky Vs Flettner: The Single rotor Helicopter (http://www.youtube.com/watch?v=mo8_C5J3F3o&feature=player_embedded)

Dave

hillberg
10-09-2010, 02:41 PM
Poor Anton was on the losing side,Winners get to rewrite history, Its like the wrights 1948 contract with the smithsonium ,For the wright flyer the museum locked out other inventers that flew before them,No good for anyone.Check out the Hiller museum.....

quadrirotor
09-05-2011, 07:35 AM
Related threads:

http://www.rotaryforum.com/forum/showthread.php?t=18431

http://www.rotaryforum.com/forum/showthread.php?t=10429

quadrirotor
02-14-2013, 02:12 PM
May be there is something there:

http://www.enterprise-europe-scotland.com/sct/services/enquire.asp?id=12%20BE%200324%203QZY&EnquiryType=BBS&reftype=RSS&refid=


Could be related to this thread:

http://www.rotaryforum.com/forum/showthread.php?t=2067

And also this one on the turbine...

http://www.rotaryforum.com/forum/showthread.php?t=9865

And this one too...

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

Rotor Rooter
02-14-2013, 08:00 PM
Poor Anton was on the losing side, Winners get to rewrite history, Its like the wrights 1948 contract with the smithsonium , For the wright flyer the museum locked out other inventers that flew before them, No good for anyone. Check out the Hiller museum.....

Yes.

Prouty deserves admiration for his informative and easily understandable information on Single+Tail rotorcraft. But, his latest article in the January/February 2013 issue of Vertiflite is entitled 'A New Concept?'.
It is about the Eurocopter X3.

http://www.eurocopter.com/site/docs_wsw/RUB_1099/CDPH-2603-188-1.jpg


He gives credit to the Fairey rotorcraft.

http://www.aviastar.org/foto/gallery/britain/fairey_gyrodyne_1.jpg


But there is no mention of Anton Flettner's FL-185; which is shown on Post #142 in this thread.



Advancement is difficult when so called developers don't look outside the box.


Dave


Retarding Rotorcraft:

Flettner's plant was bombed and had to be relocated on three occasions during the 2nd World War.

Paul Cornu, who is credited as building the first helicopter, had his house bombed in the 2nd World War. Most of his material was destroyed, and he was killed.

quadrirotor
06-18-2013, 09:10 AM
Follow up of post #145...

The makers:

www.sagita.be

A proof of concept:

http://www.youtube.com/watch?feature=player_embedded&v=mhIIy4DdPHg

Info on the Turbine:

http://congress.cimne.com/eucass2013/admin/files/fileabstract/a233.pdf

hillberg
06-18-2013, 10:27 AM
need to duct the inlet for ram air recovery.

birdy
06-19-2013, 11:44 PM
Interestn thread.
And alot of information.
I hava question, of which the answer is probably in this thread sumwhere, but iv missed it.
The systm of yaw control in a differential collective coaxial machine is, i think, the most efficiant. But as has been said a few times, the effectiveness of this systm depends on the amount of collective pitch at the time.
Full power collective pitch would give the strongest yaw control while nearing free wheeling collective pitch would give minimal control.
My question is bout the reports that yaw control is reversed dureing an auto.
How could this be?
I would have expected nill yaw control, not reversed control.
If you are useing a slightly vairied load between the rotors to control yaw, then its the draggyest rotor the machine will rotate against.
But in an auto, when there is no torque supplied to the rotor from the machine, [ its freewheeln] how could vairied rotor drag have any influence over the frame??

C. Beaty
06-20-2013, 01:36 AM
I would have expected nill yaw control, not reversed control.If you are useing a slightly vairied load between the rotors to control yaw, then its the draggyest rotor the machine will rotate against.
But in an auto, when there is no torque supplied to the rotor from the machine, [ its freewheeln] how could vairied rotor drag have any influence over the frame??I usually don’t pay much attention to fantasy threads like this one but stumbled across Birdy’s comment.

It would be true if both rotors were independently freewheeling that there would be no yaw control but the gearbox with reversing gears is attached to the airframe.

When one rotor is supplying torque to the other, there is a reaction at the gearbox that tends to yaw the airframe.

Dick DeGraw’s synchopter had yaw pedal reversing built into the collective mechanism.

birdy
06-20-2013, 01:51 AM
When one rotor is supplying torque to the other, there is a reaction at the gearbox that tends to yaw the airframe.
How??
If you load one rotor with extra pitch, the drag is transferd, through the box, to the other rotor, not the machine.
Or am i getn the gear box setup assabout?
Im assuming that wen you load one rotor, it slows, and the other speeds up, as ina differential connection. Or are they hard geared to each other?
Either way, theres still no hard torque connection to the airframe, coz its free wheeln.

C. Beaty
06-20-2013, 02:13 AM
Here’s a synchopter.

Imagine, Birdy, that you’re standing on the ground, supplying torque to one shaft.

Don’t you think the synchopter would yaw in the direction you’re twisting the shaft?

That would not be the case if you were standing of the airframe while twisting the shaft. But when one rotor supplies excess torque, it comes from the outside world.

(serves me right for waking up in the middle of the of the night)

birdy
06-20-2013, 03:43 AM
Imagine, Birdy, that you’re standing on the ground, supplying torque to one shaft.

Don’t you think the synchopter would yaw in the direction you’re twisting the shaft?
Yes, of course.

But when one rotor supplies excess torque, it comes from the outside world.
I know, in the form of drag.
But, its not be'n transferred to the frame, coz its not hard linked.
Its transferred to the other rotor.

Im speakn only in autorotation.

If you had a twin rotor gyro, with the blades hard linked to spin in opposite directions, thered be no torque transferred to the frame if you pitched differentialy.
A coaxial, or even regular heli is the same thing.

C. Beaty
06-20-2013, 05:40 AM
OK Birdy, the torque is actually reacted out in the gearbox, which if not solidly bolted to the airframe, would rotate. That would be messy in a synchopter.

It may be simpler to consider a coax with gearing consisting of a pair of crown wheels and a pinion.

The pinion runs in bearings that are part of the gearbox case.

Suppose that instead of the gearbox being bolted to the airframe, it was in bearings and free to rotate. Rotate it would if torques from the pair of rotors did not exactly balance each other.

The yawing motion resulting from one rotor producing more torque than the other reacts against the airframe via the gearbox.

It’s not complicated.

Rotor Rooter
06-20-2013, 04:07 PM
Birdy you ask a good question.



Yaw:

The coaxial has excellent yaw control, which is done by varying the lift, and more importantly the drag, between the two counter-rotating rotors, while maintaining a constant total lift.

During autorotation, the airflow through much of the disks is reversed. A particular pedal input would now cause a yaw in the opposite direction, if it were not for 'pedal switching linkages' that automatically takes place in Kamov's at the onset of autorotation.

"The problem of coaxial-rotor helicopters' directional stability in autorotation has been solved in full." ~ Quote from Kamov web page, but they do not say how it has been solved.

CRAN said ~ "Dr. Gareth Padfield picked the Russian engineers up on this point [weak yaw control during autorotation] at the conference and they sheepishly said that ...'yes, it is a problem, and we achieve direction control in autorotation with the moveable fins...' or words to that effect."


Dave


A related question that was asked on PPRuNe many years ago was; What happens on an autorotative landing when the collected is raised to help in the flare.
I don't think that there was a definitive answer.

D

birdy
06-20-2013, 05:31 PM
CB, mate, either im still thick asa brick, or your not getn me argument.
Yes, all youv said is correct, but only under power.
Dissconnect that pinion from the craft [ as ina sprag dureing an auto] and any drag/torque from one shaft is simply transferred to the other, through the pinion gear. Theres nuthn on the end of the pinion shaft to restrict any rotation, only the other crown wheel.

Under power, wen the sprag is closed, and one shaft is tryn to slow [ coz sumone has increased its pitch], the torque is taken up through the pinion gear, into the frame, creating the desired yaw.

A particular pedal input would now cause a yaw in the opposite direction, if it were not for 'pedal switching linkages' that automatically takes place in Kamov's at the onset of autorotation.
Yes Dave, I read that, but it only said it happened, not why.
I cant see how any torque can be transferred to a aircraft from a free wheeln rotor.


Hang on, I think a penny dropped.

Rotor Rooter
06-20-2013, 07:04 PM
Birdy,

If the penny is still rolling around this might be of interest. OTHER: Miscellaneous - Thoughtless Idea - Coaxial Transmission w/ Yaw Control (http://www.unicopter.com/0954.html)

Many years ago Bob Pegg had asked if he could use this idea in his PAM-100B (http://www.aviastar.org/helicopters_eng/pam.php).

I've no idea whether he used it or not, but a search just now brought this video up.

EyeFly 8-7-2011 - YouTube (http://www.youtube.com/watch?v=8-fde2AwzHw)


Dave

C. Beaty
06-20-2013, 07:10 PM
Birdy, your imagination has to be coaxed.

I’ve added a gear case. Suppose the gearcase was mounted in bearings and free to rotate.

No torque could ever be transmitted to the airframe.

Imagine the pinion was driven by an electric motor, bolted to the gearcase and also free to rotate with it.

We would have a torqueless drive; even while the rotors were being driven, no torque would be exerted against the airframe.
If one rotor had more collective than the other, it would run slower than the other and the gearcase would spin at the speed difference.

That’s what Bensen did with one of his helicopters except for using a differential gearset rather than a floating gearcase.
The differential gearset provided the equivalent of a floating gearcase.

Now, imagine we’re back to normal with the gearcase bolted to the airframe. You’re standing on the ground twisting one of the shafts.
The torque you’re applying tries to rotate its crown wheel, rotating the pinion which in turn tries to rotate the other crown wheel in the opposite direction.
But if the other crown wheel resists, the pinion tries to rotate the gearbox.
However, since the gearcase is bolted to the airframe, the torque you apply tries to yaw the airframe.

birdy
06-20-2013, 09:01 PM
Ping. ;)

Ill be driven most of tmorrow, so ill have plenty of time to get the grey cells into gear.

C. Beaty
06-21-2013, 05:42 AM
Here’s a schematic of Bensen’s torqueless drive for a coax helicopter.

It’s not intended to be a practical drive, the “V’ belt drive is only for illustration.

The differential provides an equal torque split between the two rotors, whatever the speed ratios.
Since torques are always equal but in opposite directions, no torque is ever exerted against the airframe. Speed difference between the two rotors is taken up in the differential.

Keep in mind that yawing motion of the airframe can only be accomplished by a connection with the outside world. No arrangement of gears and levers can yaw the airframe without that connection.

Bensen’s yaw control was via a small engine/propeller blowing on a conventional rudder.

Rotor Rooter
06-21-2013, 12:03 PM
To my understanding, Birdy's questions in post #149 are ;
1/ "The system of yaw control in a differential collective coaxial machine”, and
2/ “yaw control is reversed dureing an auto”


The subject is a difficult one for even for the experts. Referring to the note in post #155.
~ Kamov is, arguably, the most knowledgeable company on coaxial helicopters.
~ Gareth Padfield is the head of Helicopter Aerodynamics Section at Defense Research Agency in England. His book Helicopter Flight Dynamics: The theory and Application of Flying Qualities and Simulation Modeling (http://books.google.ca/books/about/Helicopter_Flight_Dynamics.html?id=ewVI57iyLRwC) is over 500 pages and extremely complex.


This sketch shows the Yaw control for different configurations. (http://www.unicopter.com/B318.html)
For ‘conventional’ coaxial and intermeshing helicopters it is by differential torque between rotors. These ‘conventional’ helicopters cannot vary the rotation speed between their 2 rotors because they must maintain constant blade crossing azimuths; both coaxial and intermeshing. But, the blades on these helicopters can change their pitch; by swashplate, etc.


Rotors that do not have the ability to change the pitch of their blades must; vary their RPMs differentially, or put drag tabs on the blades, or place a rudder in the rotors downwash, or have separate small propellers etc.

Chuck mentions in his latest post that “Bensen's yaw control was via a small engine/propeller blowing on a conventional rudder.” In other words, the yaw control on Bensen’s coaxial helicopter has nothing to do with the rotor system. This is basically the same as the two small propellers in Pegg’s PAM-110B, which is linked to in post #157.

It is interesting (for me at least) to see that Pegg's newer 1/5-scale helicopter does not appear to have these small propellers.

For the ‘conventional’ coaxial and intermeshing helicopters, autorotation, is a meaningful concern since they do not use the so-called ‘band-aid’ type of solutions.


Dave

Rotor Rooter
06-22-2013, 11:17 AM
Birdy, I think that this will answer your specific question.

Coaxial and Intermeshing helicopter use differential collective (differential torque) for yaw control.
The overrunning clutch is located between the engine and the gearbox.
The gearbox consumes 4% of the engine’s power.
The gearbox is hard coupled to the rotors.

During powered flight;
~ 96% of the power gets to the rotors and the yaw authority is strong.
~ Higher pitch on the CCW rotor will rotated the fuselage CW.

During autorotative flight:
~ Higher pitch (drag) of the CCW rotor will react back into the gearbox.
~ It will want to yaw the fuselage with it due to the friction of the gearbox (gears, bearings, seals and oil etc.)
~ Higher pitch on the CCW rotor will rotated the fuselage CCW, BUT it will be very weak.

Dave

C. Beaty
06-22-2013, 07:30 PM
Gearbox drag has nothing to do with it. It is torque differential between rotors.

All_In
06-22-2013, 07:33 PM
OK I'm lost!
Going to have to read this a few times and look a few things up.

C. Beaty
06-22-2013, 07:49 PM
Torque differential between rotors yaws the airframe whether the rotor is driven by the engine or by the airstream.

In autorotation with engine disengaged, the rotor with greater pitch has greater drag than the rotor with lower collective, the torque difference yawing the airframe, exactly the same as engine drive except torques are in reverse direction.

Bear in mind, the rotors are geared together and can’t act independently as would be the case if each had its own freewheel clutch.
Or like Bensen’s torqueless drive, a differential gear between rotors.

C. Beaty
06-22-2013, 08:18 PM
The Gyrodyne QH-50 had yaw control via rotorblade tip brakes, small vanes at blade tips that would pop out and increase the drag of its rotor.

Yaw control was identical whether the rotor was driven or autorotating. There was no reversal.

http://en.wikipedia.org/wiki/Gyrodyne_QH-50_DASH

This article doesn’t mention tip brakes, a Google search might be in order.

Rotor Rooter
06-22-2013, 08:29 PM
Chuck,

Here is your Gyrodyne QH-50 Tip-Brake page (http://www.gyrodynehelicopters.com/xron_history.htm)


Dave

C. Beaty
06-22-2013, 09:01 PM
Thanks, Dave.

The Gyrodyne patent explains yaw control via differential collective better than I can:


http://www.google.com/patents/US2835331?printsec=abstract&dq=2,835,331&ei=3nDGUY24F5LM9gTUhYGACQ#v=onepage&q=2%2C835%2C331&f=false

Rotor Rooter
06-22-2013, 09:52 PM
Chuck,

The Gyrodyne patent describes 3 methods of tip-brake yaw control; radially moving flap, radially extending probe and trialing edge clamshell.

The tip-brake (drag) is their way of getting around the inability to use differential collective for yaw during autorotation.
(Reference paragraph #2 in the link on post #167 above.)


The tip-brake is very complex but like you I assume (not having seen an exploded gearbox) that it eliminates the need for left and right pedal reversal during autorotation.


Dave

birdy
06-23-2013, 12:31 AM
Gearbox drag has nothing to do with it. It is torque differential between rotors.
Back from my boreing drive, and cept for the rum boiln off this morn'n, its sunk in.
I savvy why the reversed peddle response now. :)
Thanks.

Rotor Rooter
06-23-2013, 12:56 PM
Birdy,

You asked a very interesting question in your post #149.

I have participated in perhaps a hundred postings, plus research, related to yaw control in auto-rotation on twin-rotor helicopters.

First the easier of the two. :)

Intermeshing:
Flettner used only the rudder for yaw control during autorotation.
Kaman used pedal reversal in autorotation.
DeGraw used pedal reversal in autorotation.
This is a VERY discriptive presentation of the K-MAX yaw control (http://www.pprune.org/rotorheads/222277-how-does-kmax-control-yaw.html#post2527505)


Coaxial:
Autorotation, Kamov, Yaw & moveable tail-planes (http://www.pprune.org/rotorheads/68162-aerodynamics-coaxial-myth.html#post647314)
Aerodynamics ~ Yaw, Autorotation & the Coaxial configuration (http://www.pprune.org/rotorheads/124609-aerodynamics-yaw-autorotation-coaxial-configuration.html)
Gearbox drag has nothing to do with it. You may be correct about my speculation on the gearbox drag. - It may depend on the design of the gearing in the box(es)

It is torque differential between rotors. It is definitely not torque differential between rotors.

I savvy why the reversed peddle response now. Your thinking would be of interest. Sincerely.

Apparently, pedal reversal on the coaxial is of little to no value in autorotation.

My speculation:
Perhaps when the collective is fully down (i.e. autorotation) the application of pedal will increases the angle of attack on one rotor, BUT it may MAY decrease the angle of attack on the other rotor down into Windmill Brake State. :noidea:

No one, to my knowledge, has given a definitive answer to your question, That is why it is such an interesting one.


Dave

hillberg
06-23-2013, 01:32 PM
A logging pilot up north had to auto in an old husky, He added a little yaw & found it acted in reverse, spun in & rolled down a hill. Walked away, He said the damn peddles worked backwards WTF? Rudders don't do well unless you have forward airspeed.

birdy
06-23-2013, 10:09 PM
Wots a Husky??

Dave, ina coaxial, under autorotation, with fixed geared rotors, if you slow one,[ add pitch] it slows the other.[ coz they are hard linked]
The difference between the two is the one with extra pitch is be'n slowed by the extra drag. The other is be'n "torqued" slower, [ reversed torque]. This reversed torque is transferred through the pinion, which is hard rigged to the frame.

But, only half of the yawing power of the slowing rotor is transferred to the airfame. The other half it used up to slow the other rotor.
And it don't matter wether you take on degree of pitch off one and add one to the other, its still a 2* differential.

Don't wurry, it still don't sound rite to me either. :(
I need anatha brain numbn drive to ponder it sum more.

Rotor Rooter
06-24-2013, 12:39 AM
Birdy,

Intermeshing Husky:
http://i1.ytimg.com/vi/XV2YZxYjkUM/hqdefault.jpg

From the link to the sketch in posting #161;
The Kaman Huskie uses both differential collective pitch and opposed longitudinal cyclic together. But what about during autorotation?
The Flettner used differential torques (differential collective pitch change) and rudder and only the rudder could give steering during autorotation
_______________________________

Coaxial:
You, and Chuck, are correct if the gearing is the simple arraignment of 1 pinion driving 2 crown gears. My speculative posting #162 posting was poorly thought out and presented. Sorry.

However, when the cyclic is down, as it is in autorotation, there is a problem with yaw control and differential collective pitch will not solve it.

The problem with the Kamov coaxials has already been discussed.

Regarding the Sikorsky ~ S-69 ABC ~ From; Department of the Army Historical Summary: FY 1976. Weak directional control power in partial power descents and autorotation was observed. In future testing, improvements in autorotation directional control at low collective settings and high flare angles will be emphasized.

Here is another interesting report on yaw;
Regarding the Advancing Blade Concept (ABC) High Speed Development ~ May 1980 ~ (#3):
"However, with the rotor flying at close to autorotation at high speed, differential collective pitch has little impact on yawing moment ....."


I will stick with my speculation on #171 for now. :)


Dave

birdy
06-24-2013, 12:59 AM
Thanx, that clears it up. :)

quadrirotor
09-13-2013, 10:44 AM
The SKYTRAC in flight!

SkyTrac coaxial utility helicopter - YouTube (http://www.youtube.com/watch?v=V_S4mEZtWgM)

Blue Chips
09-13-2013, 12:19 PM
There seems to be a lot of positive in these systems and there are numerous models but still way in the minority, while they seem to be gaining in popularity I wonder why they really never seem to have been a serious contender over a conventional helicopter.

Stan V
09-13-2013, 12:38 PM
There seems to be a lot of positive in these systems and there are numerous models but still way in the minority, while they seem to be gaining in popularity I wonder why they really never seem to have been a serious contender over a conventional helicopter.

FAA certification would be a biggie!

quadrirotor
09-14-2013, 07:11 AM
The story:

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

This configuration has been qualified of "communist"!

hillberg
09-14-2013, 11:26 AM
For the extra set of blades,swashplate etc you could outfit another airframe or build a few batches of tailroter systems, Production costs. another compramize in the grand plan of flight.

quadrirotor
09-14-2013, 11:49 AM
Hillberg, can you figure out real numbers of what you pretend?

hillberg
09-14-2013, 12:02 PM
Break out any price list, Bell ,MD , Kamov etc. ($230.000 for a set of 212 blades)
Just call the manufactures on the costs.

Jason O
09-14-2013, 03:26 PM
For yaw you could have disks mounted on the rotor shafts and break pads mounted on the airframe, when you push a rudder pedal it would lightly rub on one disk or the other. No reversal in autorotation.

Atic
09-14-2013, 08:07 PM
For yaw you could have disks mounted on the rotor shafts and break pads mounted on the airframe, when you push a rudder pedal it would lightly rub on one disk or the other. No reversal in autorotation.

That wont work. Since both rotors are coupled the only thing, using your system, will do is slow down both rotor rpm. No yaw whatsopever.
You need to create differentl rotor drag for yaw via different collective or by airbrakes.

Jason O
09-14-2013, 09:55 PM
I believe it would work. Please tell me the difference between adding drag to the rotor from deploying air brakes (to a rotor that is coupled) and adding drag to a rotor by apply a brake to that rotor.

That wont work. Since both rotors are coupled the only thing, using your system, will do is slow down both rotor rpm. No yaw whatsopever.
You need to create differentl rotor drag for yaw via different collective or by airbrakes.

hillberg
09-15-2013, 11:55 AM
Benson had the shaft brakes, worked, rather have the tip air brakes, works better. mechanical brakes when worn or contaminated tend to grab a bit.

quadrirotor
09-18-2013, 08:23 AM
A news video for the ROTORFLY:

Вертолёт ROTORFLY Ð*-30.mpg - YouTube (http://www.youtube.com/watch?v=Bf7FVdiyD9Q)

Atic
09-18-2013, 12:23 PM
I believe it would work. Please tell me the difference between adding drag to the rotor from deploying air brakes (to a rotor that is coupled) and adding drag to a rotor by apply a brake to that rotor.

Hello Jason,

the difference is that with an air brake you do add drag to one rotor.When you brake on the shaft you don't add rotor drag.
If you're riding a bicycle and you apply only the front brake, does the rear wheel turn faster or slower than the front wheel or do they keep the same rev's but is the bike as a whole slowing down ?
If both rotors are' coupled via a gear system with the intention that they both rev at the same speed than braking on one rotor will cause both rotors to slow down.....I think.
I'm not an engineer or well educated for that matter so take my opinion with the proper reservations.

quadrirotor
07-08-2014, 05:51 AM
Not really homebuilt but interesting...

AVX Answer to the Future of Vertical Lift on Vimeo (http://vimeo.com/92696522)

quadrirotor
07-09-2014, 12:24 PM
But for homebuilding, this one is more suitable!...:D

quadrirotor
08-30-2014, 08:30 AM
Where are they now?

www.aerovationtech.com

hillberg
08-30-2014, 04:13 PM
Ugly as it is,, Junk yard?

quadrirotor
08-31-2014, 09:30 AM
She seems to be a "dogship"... Let's wait and see!... :D