A Helicopter for the Price of a Gyrocopter

[Rotor Rooter]

The linked web page Simple Electric Ultralight Helicopter (http://www.unicopter.com/1536.html) outlines a low cost helicopter. It is basically a gyrocopter without the engine and propeller, but, with a large electric pre-rotor and a pilot controlled collective blade pitch.

This rotorcraft may make for an interesting R & D experimental project today, plus become more and more practical as the advances of electric vehicles continues.


A serious discussion on the functional probability of this rotorcraft will be appreciated.

Dave

[scottessex]

I like the part with the 1200ft extension cord, :der: I don't think you could make FAR103 with todays current battery technology, too heavy.:noidea:

[Rotor Rooter]

I don't think you could make FAR103 with todays current battery technology, too heavy.
Maybe the battery would not be included in the FAR103 empty weight. Five gallons of battery. http://www.unicopter.com/Wink.gif

Agreed. A long flight time using today's battery and fuel cell technology would be very heavy and expensive; but tomorrow's http://www.unicopter.com/ThumbsUp.gif

Dave

[aerodynamicdon]

We won't mount the batteries in the aircraft. There will be a huge stack of them in the battery 'follow van'. connected to the gyro with a long extention cord (tether). Get to work on this. And don't we wish solar arrays were more efficient?:hippie:

[aerodynamicdon]

-should have read the article with more care. Never mind.

[quadrirotor]

Just for reference:

http://www.icon.fi/%7Ejtki/elgyro.html

[Rotor Rooter]

Quadrirotor,

Thanks for the link.

Interestingly, a link to Hughey Electricopter Corporation (http://www.hecopter.com/) had been posted to you on the thread [Very light homebuilt helicopter, post #10].

Last week the following e-mail was received;
"Dave,
I’m flattered that you actually put a message with a link to our “placeholder” web page on RotaryForum.com.

Frankly, we’re still in stealth mode, but “the cat will be out of the bag” so-to-speak when our first U.S. Patent Application is published by the USPTO in November.

As the name would suggest, the full-size (part 103) flying proof-of-concept prototype is all electric, fly-by-wire, and nothing like anyone has ever seen before.

We won’t be ready for a public demonstration until next spring, as we’re still doing IGE control trimming and the Chicago weather is not kind in the winter.

Since multiple rotors is your thing, I think you’ll want to kick yourself when you see it. http://www.unicopter.com/Smile.gif The miracle is how cheaply we can crank these out (although the production prototype is a year away).

Let the revolution begin!

Regards,

Brad Hughey
Founder & CEO
Hughey Electricopter Corporation"

An all-electric VTOL craft for $10,000 dollars sounds intriguing.

No specific details have been given and the patent that protects Mr. Hughey's idea has been filed. Therefore, the above general parameters represent an interesting technical challenge.

This thread is an attempt to develop a craft that can comply with these parameters. At this point, it is looking like it can be done.

I have assumed, correctly or incorrectly, that others on this forum who are technical disposed would enjoy working toward the possibility of a low cost and reliable recreational helicopter.


Dave

[bwhughey]

Hello All,

International IP laws being what they are, I am limited as to what I can say before the US application is officially published. I did not really intend for this to become a "coming out" venue. Nor do I imagine the moderator would tolerate much self-promotion, even if I were so inclined.

Jokes about extension cords aside, there is no getting around the energy density of fossil fuel. Our E-copter POC prototype is all electric; the production unit will be a hybrid - precisely for extended flight time considerations.

That said, the capability of lithium polymer technology might surprise you. It is, however, around 5X as expensive per watt/hour capacity as nickel metal hydride, albeit at one-third the weight. Rest assured that automotive companies are pouring billions into figuring this all out for us going forward.

I have reason to believe that the next few years will include some exciting developments in personal aviation. I am personally committed to producing "The Helicopter For The Rest of Us", although Steven Jobs might take exception to that metaphor.


Regards,

Brad

[quadrirotor]

Just for reference:

http://www.rotaryforum.com/forum/showthread.php?t=2188

[Rotor Rooter]

quadrirotor,

Was your link to Kestrel Aerospace a premonition?
See their web page. :)

Down the toilet? http://www.unicopter.com/Cry.gif ~ The aerodynamic inefficiencies of a propeller mounted on a rotating blade, combined with the intrinsic inefficiency of the rotating blade may make my idea unattractive.

Dave

[quadrirotor]

Dave, i saw their web site. I know i am gifted! but i don't think i have the gift of premonition :(...What i think, and tell, is only the results of my knowledge and wiseness!!! :)) i am also very humble!!! :0 :)

Every time i think i have a good idea, i look for the wheel of misfortune!!! :(

http://www.vstol.org/

[Rotor Rooter]

Every time i think i have a good idea, i look for the wheel of misfortune!!!

Every time I think I have a good idea, I invariably find fault.
However, after sufficient regurgitation, the occasional (very occasional) one works its way through.

After a couple of noted modification to the location and diameter of the propellers, this idea MIGHT be looking a little more attractive. http://www.unicopter.com/Smile.gif


The ability of an end-user to make the frame for a Ultralight gyrocopter from plans, and then basically bolt on a pair of purchased blade assemblies (blade c/w motor, controller and propeller) should be an attractive one; assuming that the blade assembly was reliable and economical.

[Rotor Rooter]

Here is another idea (http://www.unicopter.com/A119.html) to provoke thought.

It is simply the single blade concept (http://www.unicopter.com/ElectroRotor.html) used on a pair of blades.
Its disadvantage is the need to counter the rotor's torque.

Dave


Perhaps it's time to get back to more practical things, such as contemplating whether a NF or a NC nut should be used on a NC bolt.

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

[quadrirotor]

Here you have the gas-engine version, with counter-rotating blades, so no need for more reaction device other than a small vane in the back!!!:

http://www.rotaryforum.com/forum/showthread.php?t=7144

[karlbamforth]

No real need for two blades. Bolkow built this single bladed heli that flew fine.

If a piston engine or electric motor driving a prop replaced the balance weight there would be no need for a tail rotor.

Can't remember who it was, but someone suggested a small electric motor attached to the main shaft would provide yaw control by applying drag or drive to the shaft.

The lower pic is a flight simulator as they only built single seaters to start with.

[quadrirotor]

Karl, this could be simpler:

[quadrirotor]

But may be the best concept:

[karlbamforth]

Hi Quad,

Yep that is just what I was thinking.
I have pretty much discounted piston engines up there as the centrifugal loads would cause havoc with piston, bearings etc not to mention carburation.
One thought was to put electric motors up on a flybar but set in line so a thrust bearing rather than a roller bearing takes the weight of the motor then drive the props thro a right angle gearbox.

I have thought of putting small turbines in the blades and have a friend who builds them comercially for the french military. I am trying to get him to build me two to mount on rotor blades. I would mount them inline as you show in the pic for the same reasons as above, but would probably fit them at the tip end so the blade only has to be strong enough to take the centrifugal load rather than carry a duct and protection from the heat. I think ducting the jetefflux over any distance there would be considerable losses.

Props would be better for noise and can probably be bought off the shelf.
Jets would be pretty noisy.
I have an electric motor here that is about the size of a car alternator and has been fitted in a BMW. It moved the car at 40 mph. If anything it is lighter than some of the small lawnmower type piston engines and I bet one of those lawnmower things wouldn't move a BMW.
Can't wait to try it but as usual always more important things to spend cash on. LOL

[quadrirotor]

May be this concept:

[Ga6riel]

that last image doesnt take much account for the 90 degree gearboxes required, or the bearings to support the shafts. Gas motors up there has to be one of the craziest solutions fraught with potential for inflight failure.

Electric power transfer is about the only reliable answer, but then you have to contend with a significantly heavier rotor system, the aerodynamic losses and the safety that departs from its inclusion. After that, I couldnt get a spec APU that had enough output to supply the motors.

Despit being unsure about the induced drag environment for rotors so equiped, Im pretty sure it can be done, but the safety concerns me so much that I stopped publishing data for a paper prototype here.

G at the tips of an 'ordinary' rotor is around 160G

[karlbamforth]

Hi Ga6riel,
I agree with your comment about the gas motors, forgetting about the fire hazard i doubt their bearings and piston rings would last much more than an hour or two.
It is possible to get quite high power but low weight electric motors these days, but for the reasons you mentioned I would be tempted to put them on a "flybar" setup keeping the weight inboard and slowing down the speed we gotta swing them at which would be essential to prevent high prop tip speed.

I think in the image the props are folding type, that would fold back with a loss of power reducing drag. Again this is the way I would go if using props.

If for some reason someone did want to put the props at the tips maybe small vane air motors would be the way to go. It would be fairly simple and lightweight to duct the air along the blades, indeed centrifugal pumping should help the flow.

I am sure this can be done in some form or another. It will be unlikley to replace conventional helis or be more economical to operate but for us wannabe heli pilots it should work as a cheap sports/fun machine.

[gyrofly]

I remember seeing on TV about 20 something years ago where a guy made an electric helicopter flying machine that used parts from a washing machine for the transmission etc. No kidding...It used a long extension cord and he flew it in his back yard to about 20 feet.

[Rotor Rooter]

What about this idea?

http://www.unicopter.com/1536-F.gif

General:
A teetering rotor assembly that bolts to the rotational bearing on the top of the gyrocopter cyclic control system.
Cyclic control is by conventional gyrocopter flight controls.
Collective, from autorotation pitch to maximum pitch, is by power from an electric motor.

Motor:
There is a single high-speed electric motor and the center of the rotor, with the centerline of the motor aligned with the blade pitch axis.
Both the motor's rotor (armature) and the motor's frame (stator) rotate, and they rotate in opposite directions.

Propeller:
A folding propeller is mounted behind the trailing edge of both blades.
Its axis of rotation is slightly below the blades feathering axis. This is done so that increasing the motor's power will increase the pitch of both blades. (torque-pitch coupling)
The blade rotates inside down. (The propeller's blades will be experiencing a much faster inflow airspeed when they are pointing outward, away from the mast, then when they are pointing inward, toward the mast. This problem exists when the craft is at hover or in transitional flight. It also exists when the propeller is on the advancing side and on the retreating side.)
It is located as far out the rotor blade as is possible. This is done to provide better thrust, and to minimize the aerodynamic differential between when the propeller blade pointing toward the hub and when it is pointing toward the rotor blade's tip.

Power Transmission:
Behind the propeller is a 90º miter-gear set.
One gear is attached to the propeller shaft and the other gear is attached to a torque-tube, which runs from the motor to this gear.
One torque-tube is attached to the motor's shaft and the other torque-tube is attached to the motor's frame.
The torque tube is manufactured from carbon composite. It will flex with the blade but it is rigid in torsion.

Dave

[quadrirotor]

Yes Dave, it's a good idea to be tried...You know i am not eager to invest time and money in R&DD...I am always searching for pieces we could buy and use out of the boxe...And i wounder if this weed-eater could do the job? is it powerfull enough? anyway the transmission is interesting enough!!!

[Rotor Rooter]

quadrirotor,

Combine your idea, with this for jump takeoff and you might have something. :D

http://www.unicopter.com/JumpTakeoff2.gif

[Ga6riel]

the first issue i see is that the shafts and subsequent gearbox need space which would otherwise be taken up by the spar.

Chuck was saying (in a conversation appertaining to mass balance weights) that even the most aerodynamic blisters have a huge effect on the rotor, re autorotation.

[Rotor Rooter]

Ga6riel,

Thanks for the points.

The inner portion of a rotor blade isn't good for much lift so perhaps the airfoil, out to the prop, might be a NACA0018 or NACA0024, with the torque-tube inside a hollow spar.

The blister for the gearbox may serve as a faring for the hub of the propeller. However, I don't know what sort of efficient gearing could be employed to get the propeller's axis 2-3" below the torque-tube's axis.

All somewhat similar to the brantly's rotor (http://www.brantly.com/picts_ground.htm).


Just some more thoughts.

Dave

[Ga6riel]

i have seen German rotors arranged like that too

thing is, my natural inclination would have been to place the props either at the tips, or about 2ft of the rotor span back. This becuase the lift along the blade, and therefore the drag is about equal there, being that the last 2ft of rotor span supports 1/2 the weight of the machine.

it seems to me that the technological answer is a very narrow diameter motor placed in situ with the prop, even on the prop hub.

[Rotor Rooter]

Ga6riel,

A narrow diameter motor will have the advantage of being lighter and more aerodynamic. It would also have a high RPM. However would the attached propeller be able to operate near the tip of the rotor?

If the rotor is turning at 325 rpm and the rotor blade radius is 12 ft, then the tip speed = 325 x 12 x 2 x pi = 24,514 fpm = 408 fps = mach 0.37.

If the propeller is 26 x 15 and it's efficiency is 0.8, its speed = (408 / (15/12) ) / 0.85 = 381 rps = 22,860 rpm.

Since the propeller is 26 x 15 it's tip speed = 22,860 rpm x (26/12) x pi = 155,666 fpm = 1,769 fps = mach 2.39.

Assuming the above math is correct it would appear that the propeller would have to be located quite a bit inboard on the blade.

__________

Another interesting and unfortunate situation appears to be that the motor and propeller should rotate upward on the side closest to the mast. This is so that when powered the gyroscopic precession of the two rotating about the mast will pitch the blade up.

Unfortunately, I think that the best aerodynamic rotation for the propeller will be downward on the side closes to the mast. This is because when the propeller blades are closer to the mast they will be experiencing a lower free air velocity then when they are furthest from the mast. When they are experiencing this lower air velocity, their high pitch will want to 'swirl' the air and it will be best if they 'swirl' the air downward and generate some lift.

Dave

[quadrirotor]

Dave can you implement the picture?

[Ga6riel]

what would be wrong with more pitch Dave ?

[LGoodhind]

>Motor: There is a single high-speed electric motor and the center of the rotor, with the centerline of the motor aligned with the blade pitch axis. Both the motor's rotor (armature) and the motor's frame (stator) rotate, and they rotate in opposite directions.

How much horsepower would you want to put into these two props?

Regardless, multiply horsepower by 745 watts/hp and the next question is how will you get this much power into a motor which, as described, is rotating around it's own axis in addition to being above the universal joint of the rotor and spinning in that plane as well?

Failure modes? Additional mechanical complexity. How about the electrical density of real batteries that you can really buy? Assume that they can double the density. This is beyond a "big" if- even if this does happen in our lifetime how much would such an exotic battery cost?

Assuming an optimistic 60% efficiency in using an air screw to push (or pull- same thing) the rotor around in circles, isn't this approach less efficient and more complicated than a coaxial helicopter?

[Ga6riel]

ofcourse the state of the art isnt going to leave you aghast at its sustained flight capability. That said there are other directions.

A sophisticated APU would have to compete with a conventional engine and transmission for weight. It is likely that only turbines could do this as about 28kw is required. Fuel cells are another road. It would compete with conventional arrangements, given no requirement for anti-torque. Transmission through the rotor would be via slip rings.

So why would you do this?
It would plainly be easier to fly, and that means safer to fly. Some 15% of helo accidents involve the tail rotor, eliminating that would make it 15% safer. Add to that electrical equipment is very reliable, certainly ever moreso than 2 stroke technology. For low time pilots the ease of handling would prove itself faster to learn, and uncomplicated to operate.

[LGoodhind]

Pushing 28KW (~37HP available) through two sets of commutators for 60% efficiency at conversion (~22HP delivered) to rotor torque seems like lots of work and effort to apply a specific solution rather than focusing on the problem. Does the 28Kw estimate come from a shaft driven example?

My question was how this is an improvement over a shaft driven coaxial helicopter.

[Ga6riel]

no its a drag estimate from a 21ft dia rotor

you seem to work on the idea that coaxials are easy
where the risks of blade collisions are great
only avoided with a rather large intermediate mast
thats mechanicly not so simple to analyse or construct
then you need a reduction g'box
and a coaxial g'box
pressure oil lubrication ?
oil coolers ?
majorly more complex cyclic?

you cant buy these parts at the corner store, you would need to make them
and one inflight failure would end it all

[Rotor Rooter]

Quadrirotor,

"Dave can you implement the picture?"
Unfortunately no. Your craft has CW rotation so it is obviously European and I don't know how to work in the metric system. :)


Ga6riel,

"what would be wrong with more pitch"
True. How much pitch do you think can be used before it becomes inefficient for flight and impossible for initial rotation?

A 20º pitch appears to be the normal maximum. In the proceeding example, this will result in the propeller's tip speed dropping from Mach 2.39 to Mach 1.28. Moving the propeller inboard from the tip to 0.8 of rotor-blade radius will lower it further to Mach 1.02.


Larry,

"How much horsepower would you want to put into these two props?'
Required power to hover for 500 lb. GW, from Prouty's calculations; by Momentum theory it is 21.9 hp and by Blade Element theory it is 17.3 hp. Of course, his calculations are intended for much larger helicopters. There will be positives such as no tail rotor and negatives such as the aerodynamic transmission of power (propeller) to the rotor, as you have mentioned.


Larry you're into RC how about this. 10 hp out of a motor weighing 3 lbs. :eek:

http://www.unicopter.com/PredatorPowerPlant.jpg

Dave

[Ga6riel]

i found induced drag really difficult to calculate for a rotor

[LGoodhind]

Hiya- I was speaking about an electric helicopter for an apples/apples comparison and was talking about a counter-rotating Hiller servo rotor with shorter blades and a wider chord to address the other things you mentioned; fewer moving parts and 30% more torque. I can't imagine that a counter rotating gearbox is more of an engineering challenge than getting a useful amount of power to a 30HP motor spining in two planes but that's an uneducated opinion.

[quadrirotor]

All you need is...

[Rotor Rooter]

Blade mounted propulsors appear to be limited to hover and slow transitional flight.

As the forward velocity of the craft increases the airflow over the advancing blade will increase. This mean that the propeller's rpm (and tip Mach number) must be higher.
When the propeller is on the retreating side, its thrust is in opposition to the direction that the craft is moving.


Any thoughts?

___________________

A possible means of overcoming this concern might be some idea similar to Root Fan Rotor (http://www.unicopter.com/0002.html), but this probably removes the rotor from the 'low cost' goal of this thread.

[Ga6riel]

hmm I did wonder about this
what you mean is essentially
the retreating blade +V wont recover enough speed for the advancing side
is that it ?

[quadrirotor]

All depends, Dave, on what you want: a backpack helo or could it be on skid? what is your budget? for one follish person only, i suppose?

you have this one that flies very well!

http://www.innovatortech.ca/

[Rotor Rooter]

Ga6riel,what you mean is essentially the retreating blade +V wont recover enough speed for the advancing side
is that it ? Regarding concern 2.

Both propulsors will provide rotation to the rotor during hover, and this is OK. However during forward flight, it seem that it will be counterproductive to be flying the craft North and have attached propulsors that are spending quite a bit of their time trying to push the craft South. (ie. on the retreating side)

The proposed idea on the linked [Root Fan Rotor] is that, simplistically, the thrusters only work on the advancing side during forward flight. The thruster is located so close to the blade's root that the blade's drag moment outboard of the thruster is balanced by the drag moment of the fuselage on the other side of the thrust.


Since you brought the subject up. http://www.unicopter.com/Wink.gif To get really wild, here was an idea to have differential blade RPM between the advancing and the retreading sides. Cyclical RRPM (http://www.unicopter.com/1501.html) :o

[Ga6riel]

i got to thinking today (always dangerous) why then are tip jets successful
XH-20 Little Henry Research Helicopter
First flight: Aug. 29, 1947
Rotor diameter: 20 feet
Length: 12 feet 6 inches
Height: 6 feet 8 inches
Empty weight: 290 pounds
Power plant: Two small ramjet engines mounted at the rotor tips
Speed: 50 mph

so how about this
a double sided centrifugal compressor
perhaps 10" dia (really depends on motor rpm)
tip mounted with the profile of the compressor edge on, laid flat with the blade
electric (like the one you have) motor mounted centraly inside

this provides are usefully larger diameter for a better 'e'
but without the drag imposed by a conventional front on compressor

[Rotor Rooter]

i got to thinking today (always dangerous) why then are tip jets successfulJust speculation, but perhaps tip jets are a little more successful because the air velocity that they produce allows the sum of the rotational speed, at the propulsor, plus the craft's forward speed to be higher than a propeller could. Also, I believe that the Faridyne rotorcraft only used its tip jets for hover and transition.

Your double-sided centrifugal compressor is an intriguing idea. Will there be a problem for the high velocity free-air at the blade tip to make the sharp right-angle turn into the compressor?

[Ga6riel]

no
Intake, helped by ram, is pushed into the centre from above and below, and flung out to the perimeter. Any centrifugal intake pattern makes a right angle turn anyway, in some ways, this might actually improve the flow for air and pressure would naturally vector to the rear of the difuser and therefore straight onto the centrifuge. It would be necessary to use the difuser to keep the intake and rotational air in the centrifuge separate, thats about the only unusual thing.

Like some turbo chargers of centrifugal design, the eflux parts on on side of the compressor, tangental to the circumference.

[Rotor Rooter]

Ga6riel,

Sorry to not reply much earlier but I was despondently coming to the conclusion that it may not be possibly to simply 'bolt' a rotor into the teetering hinge of a gyrocopter and achieve hovering capability.

At the risk of sounding too pessimistic, your idea for a tip mounted radial blower is intriguing, but it may have terminal limitations. Some limitations might be, weight, drag during autorotation and gyroscopic precession effects.

What may be interesting is the use of a single larger version of your blower in a root driven rotor (http://www.unicopter.com/0002.html) with azmith variable thrust. Of course, this is certainly not going to be a modified gyrocopter.

Perhaps the soundest remark was Larry's when he said " Assuming an optimistic 60% efficiency in using an air screw to push (or pull- same thing) the rotor around in circles, isn't this approach less efficient and more complicated than a coaxial helicopter?"


Dave

[Ga6riel]

hi Dave
well i know a lot less about the potential for success on a teetering hinge gyrocopter rotor, but i have come to agree about the rest

as to Larry's remarks
that may well be true on a pure efficiency background
but its perhaps a different story when it comes to mechanical simplicity
the centrifugal blower so fitted may not be the right answer
but i still believe that a blown rotor has significant potential
perhaps its back to the fairy ultralight and the djin

[Ga6riel]

an APU ducted into a large turbocharger provides a hot/drive side and a cold/driven side. such a setup wouldnt weigh a whole lot at all, perhaps 100lbs or so. on the voljet the hot side is used for lateral control and the cold side goes into the rotor.

or one could avoid using a gas turbine and the attendant fuel consumption and heat issues, and just opt for a conventional reciprocating engine and driven centrifugal compressor. whatever the compressor drive with this arrangement the size and weight of the compressor part are less of an issue, but is ofcourse much heavier than a turbine plant. 60 to 80hp makes for a lot of compressor.

the mast would be hollow with the teeter hinge hung around it, held captive by top and bottom bearings. this would allow a T fitting and bearing at the top with short flexible connections to the rotors. the flexible lines allow the rotor to teeter. the location of eflux jets would be dependent on the compressors performance, speed vs pressure. the only differences here with a conventional rotor are the drag of the T connection bearing and the dynamic drag of the flexible lines.

[quadrirotor]

post #24
http://www.rotaryforum.com/forum/showthread.php?t=7858

[Rotor Rooter]

Ga6riel,

A couple of questions;

Would the blades be able to have a sufficiently large X-sectional area to transmit the airflow?

Is there a means of applying collective?


From a personal perspective, I do not like the idea of a propulsor pushing a portion of the craft's mass in a direction that is opposite to the direction that the craft wants to go.

___________________

[i]The off topic portion of this post has been moved to a new thread; called Jellyfish Aircraft



Dave

[Ga6riel]

yes
and yes,
outside of the rotor propulsion its still a single rotor helicopter, and collective pitch control is the safest way of dealing with it. i just think that a fixed pitch ala model helo's could be too slow to control a decent, given there is a lot of potential for lag in accelerating the system

i think the tip-jet, for want of a better term, its potentially so small in sectional area not to matter. unlike the tip-prop it doesnt suffer from anything like the same drag regime. so its just back to translational lift rotor dynamics.

on another tack, we already know that it works as a system, but it would be better if it could use an 'off the rack' collective rotor hub like the mosquitoe's

[Rotor Rooter]

Ga6riel,

Here is an 'off-the-wall' thought for an 'jet' driven rotor. The rotor might be; a tip jet, a root jet, a strip jet along the full or portion of the span of the blade, or some combination of the foregoing.

The intent is to provide a helicopter, which has a single main rotor, the ability to produce faster forward speeds. This would be accomplished by giving the jets the ability to redirect their thrust vectors at a rate of 1 per rotor revolution.

When the blade is on the advancing side, it's thrust will be aft and this will contribute to the rotation the rotor and the advancement the craft.

When the blade is on the retreating side, its thrust will have a downward component. This will partially contribute to the rotation of the rotor, but primarily it will provide lift on the retreating side of the rotor disk. This lift will mean that the pitch of this blade will be less, the drag will be less, the blade will not be subjected to tip stall, and the craft can fly with a higher forward velocity.

____________

A second possible feature of having a 1/rev variable thrust vector might be that the blades can have a rigid attachment to the hub, ala Kaman, and the thrust vectoring be used to provided pitch change for collective and cyclic control.


Dave

[Rotor Rooter]

The Hughey Electrocopter Corporation's patent application has been released.

20060266881 (http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220060266881%22.PGNR.&OS=DN/20060266881&RS=DN/20060266881)