Is CLT,HS theTaliban Terrorist of gyros

[Redbaron]

you can hear Ron Herron talk about his adjustable horizontal tailplane for countering propellor torque in this interview with paul plack.

‪Aero-TV: Ron Herron's Little Wing - Going Back to Traditional Autogyro Roots‬‏ - YouTube

 

[C. Beaty]

Thanks Red, for that clip of Ron’s interview. I had heard him discuss torque compensation several times but had never seen the clip.

 

[Redbaron]

no problem cb, your infinite knowledge is a treat for the mind! :rapture:

Thanks Red, for that clip of Ron’s interview. I had heard him discuss torque compensation several times but had never seen the clip.

 

[birdy]

Because the rotor quits producing its usual forces, nothing we do with the rotor during zero G will have any effect. Think about this concept carefully:
Not quite.
We still have cyclic control.
Iv been 'floatn' on the seat many times at the top ofa short climb and centered the stick to stomp a peddle and sometimes theres a roll induced from [ im thinkn] prop gyrscopics and i can still control it with the rotor, with more authority than at one G. The cyclic responce at near 0G seems to be higher than at one G.

Not that itll help ina HTL machine coz youll go over before you can move the stick.

 

[Doug Riley]

Birdy, in zero G you still have cyclic control of the rotor, in the sense that moving the stick tilts the rotor. If the rotor isn't pulling up on the frame, though, then tilting the rotor won't result in a tilt of the frame. The string has gone slack, so to speak.

If you get a response in the frame, then you're not at zero G -- maybe fractional (less than 1.0) pos G.

With some of the very HTL, powerful machines, you don't have to go all the way to zero G to start a PPO. PPO's feed on themselves unless you snap the throttle shut.

 

[birdy]

I hear you Doug, im just be'n agumentative.

But,
If the rotor isn't pulling up on the frame, though, then tilting the rotor won't result in a tilt of the frame. The string has gone slack, so to speak.
coz you still have cyclic, you can realine the disc so's its got airflow and retention the string.

 

[Friendly]

Back when I was flying my RAF, it was impossible not to be aware of the shortcomings its HTL created. I enjoyed flying that machine, but flew respecting it not to be near as friendly should I unload the rotor by my action or had nature step in with a big downdraft. Maneuvers like the one that killed the pilot in the Frog RAF unfortunately have happened way too many times. Had he had CLT, he more than likely would not have bunted. Sure, you shouldn't be unloading your rotor like that in a zoom climb, but to unload your rotor with lots of power pushing at the distance an RAF's thrustline is offset, is a perfect recipe for a disaster. More than likely, if the pilot had flown it respecting its HTL, and understanding the physics of why, he would be still flying his RAF safely as do many others. Its the ones that don't understand what a HTL can do if you push it unloading the rotor. Too many have tumbled out of the skies while I was flying mine. When I started flying my SparrowHawk is when I could feel what stability was. I agree with the person that commented how Brian would notice the difference when he flies his Genesis. Stan

Stan,
I agree with you on that, The Genesis will introduce some awareness for a lot of people who are flying marginal designs without knowing it because of their flying skills.
Brian,
This is not meat to be offensive, so please do not take it be so.
You RAF has an HS on it. Does it fly the same without it? Not can you fly it, without the HS. But is there a difference?
No singling you out, but I have never understood why RAF owners would argue for the RAF design, yet they were no longer flying the RAF design, instead they were flying the Modified RAFs . There must be something of value in the HS to add it to the RAF.

 

[Doug Riley]

Birdy:

Yup, you can re-tension the string as long as the machine hasn't flipped onto its back in the meantime. That's the difference between stable machines and not.

The Peasant Frog crash that Stan mentions was typical of the older pattern of PPO crashes during the Bensen era -- zoom climb starting with a fair amount of speed. The speed is traded for more "zoom," making it easier to unload the rotor more completely and for longer. Note that the "Frog" had a H-stab. The HTL offset on the RAF, combined with its powerful engine, make it very difficult to bolt on enough H-stab to prevent PPO in aggravated curcumstances like this.

Vance is right, though, that PPO's changed with the coming of the re-drive era. Redrive gyros with the prop above the engine tend to have such a large HTL distance that some of them will PPO from normal, unaccelerated flight, without first porpoising or zooming. In these cases, they're often climbing out at full power at normal airspeed.

 

[Alan_Cheatham]

Maybe one way to think about this is to put it into terms that are more familiar, many pilots have either flown full scale or R/C airplanes and tried the vertical prop hang maneuver.

An airplane handing by it's prop has wings unloaded, engine thrusting placing torque and pulling forces into the fuselage with air blowing down it's length. As the aircrafts indicated airspeed reaches zero all directional stability is lost as there is no longer any relative airflow across the tail, but if the tail surfaces are in the props wash they can be used to develop counter balancing forces.

Now imagine a gyroplane trying to do the same maneuver, what design characteristics become important ......................

Obviously zero G and zero airspeed are a worse case scenario but it illustrates the point.

.

 

[StanFoster]

Doug- I distinctly remember the Peasant Frog having a high cambered upside down airfoil for his HS, but it was on the keel below the propwash. It had what I thought a vewry high negative angle of attack and it had that high lft airfoil shape to boot. I was comparing my 2 degree negative incidence to his MUCH more incidence, and was wondering how much more downforce his had over mine Parham stab. I would assume it was too much with good airspeed, but loosing most of its down force at low airspeed. Stan

 

[Doug Riley]

Stan: Yes, a H-stab intended to PPO-proof a HTL gyro MUST be at least partly in the propwash. There is no choice. It won't work at low airspeeds otherwise.

All the camber, stab-area and incidence in the world won't make an airfoil function if it has no airflow. A keel-mounted stab on a pusher gyro gets no flow to speak of at low airspeeds.

It doesn't get much at higher airspeeds, either, if there's a low-mounted, fat cabin with a blank-wall backside upstream.

 

[C. Beaty]

It is important to remember that a propeller is not a rocket motor; i.e., what goes in comes out.

The propeller slipstream is the vector sum of free stream and propeller added velocity. If the airspeed is 50 mph and the propeller adds another 50 mph with the machine in a 10º yaw, the slipstream will be 100 mph with a 5º yaw angle. (This is approximate to avoid acute angle trig)

But airfoil lift varies as the square of airspeed, double the airspeed and lift is 4x as great. One half the angle at twice the airspeed doubles the effectiveness as compared to a stabilizer completely exposed to the freestream but out of the prop slipstream.

This holds even in the case of objects; cabin, pilot’s body, etc. blocking direct flow into the propeller disc. In traveling around interfering objects, the relationship of yawed flow is preserved.