New rotorcraft concepts

[henryk]

pushers are stabilizing.

-f.e. Hiller Platform=

 

[dukkbutt]

Isn’t a jet a pusher?

Yes and I'm not sure what the difference was. I had the same thought after I posted and was coming back to comment. Only thought I have is the force on the aircraft being applied at the prop disc vs. somewhere further forward in the jet engine. Total guess, though.

I know I read that long ago but I don't know why it was considered to be true.

 

[John.Roo]

Tractor props are destabilizing, pushers are stabilizing. That's one reason early flying wings that switched from props to jets had stability issues.

I don´t think that this is valid for gyroplanes

Tractor gyroplanes are better in many ways except one - pilot´s vissibility.
Normal pilots are thinking that gyroplane = helicopter for less money
Tractor gyroplane like Little Wing has higher safety and better performance than "normal" pusher gyroplane (comparing performance with same engine) only doesn´t look "cool" like a small helicopter.

Little Wing Autogyros, Inc..

 

[EzyBuildWing]

Maybe this gyro could be easily modified to electric with a direct-drive Geiger motor??
Tail-feathers could be carbon-fibre.
Large diameter slow-turning tractor prop would be efficient.
Would look super-cool.......and ultimate in simplicity.
More info on electric-gyrocopters is on the excellent website below....just click on the Link:
Electric Autogyro, is it possible?

 

[henryk]

direct-drive Geiger motor??

=but not for low RPM prerotation/rotation drive...

-the simple and effective solution=Differential Gear (Rotor/Stator of Electromotor),
we get Reaction less Drive !

=possibility in VERTICAL take off/landing + rotor drive in cruise !!!

 

[D Hillberg]

Tractor props are destabilizing, pushers are stabilizing. That's one reason early flying wings that switched from props to jets had stability issues.

Tractor gyroplanes are much more stable then pushers, PIO PPO are nearly nonexistent in early tractor designs
Flying wings are unstable due to center of pressures and C/G limits being exceeded and not thrust.
Short coupled flaperons and spoilers are not as effective as tail feathers on a stick.
no difference in jet thrust or pusher prop thrust.
Old engineer saying "Easier to pull a rope then push it" pulling is naturally more stable

 

[henryk]

is naturally more stable

-look=NEGATIVE Stability !=

 

[crusty old aviator]

Isn’t a jet a pusher?

It depends how close you are to the intake: they can literally suck you off your feet!

 

[D Hillberg]

-look=NEGATIVE Stability !=

Questions of Thrust Lift Drag Weight - and you give us Girly Toys. [Bell style flybars - ballast toes - coaxial action]
The look on one girls face as the fairy godmother face slicer went for her nose...
Go to the Rotarywing Forum and have a discussion on Pusher/Tractor Gyros.

Front wheel drive isn't worth anything either... Maybe Chinese tractors?

 

[rtfm]

Tractor props are destabilizing, pushers are stabilizing. That's one reason early flying wings that switched from props to jets had stability issues.

Is this an opinion, or do you base this on actual data?

 

[U+fly]

Is this an opinion, or do you base this on actual data?

To understand it, you have to think that behind the prop the airflow is perpendicular to the prop"disc".
If the incoming air comes sideways, in front of the prop, the air flow changes it's direction passing through the prop, creating a yaw force.
For example: the incoming air comes from the left, the resulting force is right (Newton's law).
For the prop in front of CG (tractor) the airplane want's to go more right (destabilizing), but with the prop
in back of the CG (pusher) the same force pushes the back right, so the airplane goes left (stabilizing)
For jets, it is the position of the intake that has to be considered. So on old jets like the Sabre or Mig 15, with the intake in the nose, it was very destabilizing.

 

[Mike von S.]

Tractor props are destabilizing, pushers are stabilizing. That's one reason early flying wings that switched from props to jets had stability issues.

Is this meant as a joke?
At least as regards gyrocopters, you've got it exactly backwards

 

[Mike von S.]

But why are the tractor gyros not very popular?

Because since Igor Bensen developed his flying lawnchair in the 1950s, built from aluminum tubing and mostly materials available at the local hardware store, the industry has fixated on cheap and easy to build. Autogyros aren't as capable as helicopters or as efficient as fixed wings, but the idea that the average Joe or Jane could build one at home over the course of a few weekends, for not much money, was very appealing. Also, the motorcycle style wind-in-your-face-and-unobstructed-view-ahead feels like freedom.
Unfortunately for those who died flying pushers.
In recent years much engineering has gone into designing pusher gyros to make them safer, mostly by adding tail surface area/arm and better aligning center of thrust to center of gravity, but had the industry stuck with the original tractor configuration of de la Cierva many fewer pilots would have died over the years and gyros would not have developed the bad reputation they are still stuck with.

 

[Aesquire]

Maybe this gyro could be easily modified to electric...

Neat! What/who's is that gyro?

I don't know about electric power, but I Really like that. A good thrust line, and without the cranked keel/tail boom of the pushers that compromises ground clearance, or forces excessively tall landing gear. Are plans or kits available? Looks perfect for a pt103 design.

 

[Aesquire]

I just went back & re-read this thread from the beginning.

My priority list;
First is true VTO [ not jump] and land
Second is slower min AS with better safty margine if the noise stops.
Third [ my dream] ground effect hover.

My suggestion for this 2008 mission is deflected thrust...

Deflected slipstream - Wikipedia

en.m.wikipedia.org

The Ryan VZ-3 had issues in ground effect, apparently, but it seems like a great application for multiple electric motors.

 

[EzyBuildWing]

Little Wing Autogyro's had a cool "see-through" version.....looked great.
Perhaps could be built of half-inch SQUARE 4130 tube TIG welded....all drop-saw cut so no fish-mouths to file.
Engine could be Polini Thor, or MZ 202 helicopter-engine from Mosquito(air cooled).

 

[henryk]

you give us Girly Toys.

=cheap,quick examination...

<20 $ !

 

[D Hillberg]

To understand it, you have to think that behind the prop the airflow is perpendicular to the prop"disc".
If the incoming air comes sideways, in front of the prop, the air flow changes it's direction passing through the prop, creating a yaw force.
For example: the incoming air comes from the left, the resulting force is right (Newton's law).
For the prop in front of CG (tractor) the airplane want's to go more right (destabilizing), but with the prop
in back of the CG (pusher) the same force pushes the back right, so the airplane goes left (stabilizing)
For jets, it is the position of the intake that has to be considered. So on old jets like the Sabre or Mig 15, with the intake in the nose, it was very destabilizing.

B
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Where do you come up with these mistaken opinions?


Bunny says "PLIBABBBBBBBAPPPPPPLLLAAAPPPPBIBIBIBIBI"

 

[rotax618]

Irrespective of any theoretical stabilising effect of a pusher, I can tell you from bitter experience that the airflow into a pusher can be very destabilising, it took me a lot of experimentation to solve the problem of vibration and phugoid like oscillation in yaw I encountered while test flying my Boorabee. The problem was solved after numerous experimental placement of vortex generators along the forward fuselage sides.

 

[henryk]

experimental placement of vortex generators along the forward fuselage sides.

=more detailed ?