New rotorcraft concepts

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

rotax618

Well-Known Member
Joined
Oct 31, 2005
Messages
1,658
Location
Evans Head Australia
I have long thought that the ideal “sports plane” would be based on a autogyro with partially powered rotor. Partially powering the rotor would :
1. Shorten the takeoff.
2. Providing small amount of power would overcome a large portion of the rotors induced drag, would overcome the high power requirement (1/2 all up weight in thrust) for forward flight, lowering the disk angle.
3. Eliminate or massively reduce the problems of negative “G” slowing the blades dangerously.
Obviously there would have to be a simple lightweight mechanism to overcome the torque, this could be provided in a pusher installation by having the engine mount on a transverse slide, and in a tractor by pivoting the engine frame on a vertical axis.
A gyroplane is an ideal sports plane if the problems of thrust requirement and negative “G” can be overcome - autogyros don’t stall or spin and are much smoother in rough air, can land near vertically so X-wind is not a problem.
 

henryk

Well-Known Member
Joined
Mar 8, 2010
Messages
7,412
Location
krakow,poland
I have long thought that the ideal “sports plane” would be based on a autogyro with partially powered rotor. Partially powering the rotor would :
1. Shorten the takeoff.
2. Providing small amount of power would overcome a large portion of the rotors induced drag, would overcome the high power requirement (1/2 all up weight in thrust) for forward flight, lowering the disk angle.
3. Eliminate or massively reduce the problems of negative “G” slowing the blades dangerously.
Obviously there would have to be a simple lightweight mechanism to overcome the torque, this could be provided in a pusher installation by having the engine mount on a transverse slide, and in a tractor by pivoting the engine frame on a vertical axis.
A gyroplane is an ideal sports plane if the problems of thrust requirement and negative “G” can be overcome - autogyros don’t stall or spin and are much smoother in rough air, can land near vertically so X-wind is not a problem.

=1/2 of potential...

IFF install FULL power prerotation/reactionless rotation =VTOL, helicopter like,
+economic cruise, faster as classic autogyro !

(electric variant can work withaut gear !!!)

Dick Degraw fly with DIFFERENTIAL gears !=




=look at rotor surface (AoA !)
 

rotax618

Well-Known Member
Joined
Oct 31, 2005
Messages
1,658
Location
Evans Head Australia
The Dgraw gyro is an engineering masterpiece, the gyro I was describing was to be far simpler, in the interview Dick did describe the phenomenon of a much lower disk angle and reduction of drag with a constantly powered rotor.
The simple sports gyro I described would not need collective pitch change. By just powering the rotor with say 20hp the ground run would give STOL performance without the added rotorhead complexity and provide the other safety features I described.
 

Martin W

Well-Known Member
Joined
May 14, 2021
Messages
209
.

A gyroplane is much cheaper and mechanically simpler than a helicopter thus the popularity .... if only we could have a quick launch and short takeoff.

Complicated collective pitch mechanisms and transmissions to partly power the rotor can work and there are some good examples that have been built.

Nick Lappos (Sikorsky engineer) always had a brilliant way of looking at such things ...... he would say to drop all the clutter and complicated components and weight .

Then apply the savings toward a higher powered engine and good prerotator and you will accomplish pretty much the same thing , only much simpler

.
 

henryk

Well-Known Member
Joined
Mar 8, 2010
Messages
7,412
Location
krakow,poland
gyro I described would not need collective pitch change.
=reactionless CR rotors drive,

=simple inertial automat=AoA blades proportional to the rotors RPM
+high,short power E-motor (80 kW) for VTOL regime

=NO gear,NO beavels...
 

Attachments

  • IMG_20171218_160612019 (2).jpg
    IMG_20171218_160612019 (2).jpg
    40 KB · Views: 20

rotax618

Well-Known Member
Joined
Oct 31, 2005
Messages
1,658
Location
Evans Head Australia
I’m not advocating the complexity of the Degraw machine, what I am advocating is simply a more powerful pre-rotator that is constantly engaged (with sprag clutch) and a method of deflecting the thrust engine to counter the torque. I recon that a tractor gyro would be the best configuration, the engine mount could be pivoted on the firewall in ithe vertical axis, simple hydraulic brake cylinders on the rudder peddles could be used to used to move the engine to control the yaw.
 

Heliano

Well-Known Member
Joined
Dec 24, 2015
Messages
179
Location
Campinas, SP, Brazil
Very good thread. However I would like to comment about "ideal “sports plane” would be based on a autogyro with partially powered rotor ". An autogyro has its advantages: it is simple, is controllable at very low speeds and lands anywhere. But it has one important shortcoming: it is aerodynamically inefficient. Its L/D is very low. A defunct british company named Fairey Aviation developed a large autogyro for 40 passengers in the 50s called Fairey Rotodyne, but its fuel burn was way more than that of a conventional aircraft, and it was very noisy, and the program ended up scrapped. If you need urban mobility or your distances to be flown are short, an autogyro may be a good choice. But if you intend to fly cross country for distances exceeding 100 miles, a good old nice pair of wings comes handy.
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,528
Very good thread. However I would like to comment about "ideal “sports plane” would be based on a autogyro with partially powered rotor ". An autogyro has its advantages: it is simple, is controllable at very low speeds and lands anywhere. But it has one important shortcoming: it is aerodynamically inefficient. Its L/D is very low. A defunct british company named Fairey Aviation developed a large autogyro for 40 passengers in the 50s called Fairey Rotodyne, but its fuel burn was way more than that of a conventional aircraft, and it was very noisy, and the program ended up scrapped. If you need urban mobility or your distances to be flown are short, an autogyro may be a good choice. But if you intend to fly cross country for distances exceeding 100 miles, a good old nice pair of wings comes handy.
Yes. Efficiency is poor alright. Here's an old article on the Hollman two-seat autogyro: First Two Place Homebuilder Gyroplane - Hollmann HA-2M Sportster

Two seats, 150 HP, cruise 75 MPH, climb 500 fpm, range 90 miles, useful load 430 pounds including fuel. A 172 with that same HP will cruise at 115 MPH, carry at least 800 pounds, have a range of four or five hours, and climb at 750 FPM or so. And at that, a 172 is not an efficient fixed-wing airplane, either. A clunky Piper TriPacer is better yet.
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,528
much more eficient is rotor drived mechanically (or better=electrically)!
A Robinson R22 helicopter gets better performance than an autogyro, but still needs a lot of power to haul two people and a bit of fuel. You aren't going to do it with current battery technology. Not for more than five minutes, anyway.
 

henryk

Well-Known Member
Joined
Mar 8, 2010
Messages
7,412
Location
krakow,poland
You aren't going to do it with current battery technology. Not for more than five minutes, anyway.

=battery power ONLY for vertical take off/ landing,
cruise on IC with CRDiff. propellers +generator for battery in flight charging & continue
rotor drive (reactionless !) !
 

D Hillberg

Well-Known Member
Joined
Nov 23, 2010
Messages
1,870
Location
very low low low earth orbit
Weigh in tankering batteries reduces useful load

With US LSA once you power the rotors it's not eligible for Sport Pilot...

Chicago Airways , Los Angeles Airways, New York Airways SABINA and San Francisco all gone....

A gyro's short legs wont help at all
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,528
=battery power ONLY for vertical take off/ landing,
cruise on IC with CRDiff. propellers +generator for battery in flight charging & continue
rotor drive (reactionless !) !
All of which adds up to way more weight, complexity and cost than just using the ICE. Helicopters of any sort have to be kept light even more so than fixed-wing airplanes.
 

rotax618

Well-Known Member
Joined
Oct 31, 2005
Messages
1,658
Location
Evans Head Australia
The Fairy Rotodyne was pretty successful aerodynamically, it wasn’t successful commercially because of the noise generated by the rotor tip jet engines which use compressed air from the thrust engines pumped down the hollow blades and mixed with fuel at the tips, this prevented its primary use which was to transport passengers to and from City centres.
Gyros are inefficient, partially powering the rotor makes them much more efficient by overcoming the induced drag of the rotor, this lowers the disk angle (which is the drag source).
A normal gyro requires thrust equal to half of its all up weight to fly, if you can lower the disk angle for the same lift much of the drag disappears, with the assistance of autorotation a semi-powered rotor gyro could be much more efficient than an equivalent weight helicopter - it would not hover (except in a headwind) but would be far less complex and easier to fly.
 

Heliano

Well-Known Member
Joined
Dec 24, 2015
Messages
179
Location
Campinas, SP, Brazil
Interesting point, rotax618. However a doubt remains: a powered-rotor autogyro is kind of intermediate between a unpowered-rotor autogyro and a helicopter. Those two extremes are inefficient. How can something in between be efficient? Where is the flaw in my reasoning? Be patient with me, I am just trying to learn.
 
Top