The Servo Flap Controlled Rotor for gyrocopters ?

Joe, if blue rotor wash is a water soluble liquid, its specific gravity will be close to one.
 
thx for great immages

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On lightweight helicopter, this device appears to me far too sensitive
In the paper below a two blade teetering rotor for a light helicopter is investigated. The blade dimensions are very close to gyro blades. Due to the smaller rotor speed on a gyro the torsional stiffness would have to be adapted, a fairly straightforward job if you can use state of the art FEM programs.

http://www.dtic.mil/get-tr-doc/pdf?AD=ADA480619
 
Juergen, I meant "too sensitive to onlookers watching with hands"
 
I think that the little aileron things would work on powered rotors, because the engine can/should be able to make up for the drag they induce, which is why they are used on the flettners, not really for lift, they just need to apply a descernable amount of drag the the rotor set to yaw the craft, and do it quickly and predictably....

I doubt they would be better for us than the gimble head arrangement, and to me, I doubt that anything that adds drag to a rotor system, especially an autorotating rotor system like ours would be a good thing.... as our gyro rotors are now, they autorotate freely and happily, to add drag making 'aileron' thingys on the rotors which slow down their autorotation, to me, doesn't sound like a great idea
 
A divergence of opinion on how a servo flap functions.

A divergence of opinion on how a servo flap functions.

I think that the little aileron things would work on powered rotors, because the engine can/should be able to make up for the drag they induce, which is why they are used on the flettners, not really for lift, they just need to apply a descernable amount of drag the the rotor set to yaw the craft, and do it quickly and predictably....

In my opinion the servo flap twists the blade rather than using a swash plate to reduce the forces on the cyclic and collective.

I have seen a different device on some coaxial helicopters that comes out of the tip that uses drag for yaw.

Regards, Vance
 
Poorly designed airplanes with wings too flexible torsionally often suffered aileron reversal where an up aileron would raise the wing rather than lower it.

That’s the reason fabric covered wings have “V” struts; metal covered wings, stiffer in torsion, can manage with a single lift strut.
 
IIRC, wasn't there a gyro built in Canada that had servo flaps (Avian 180) in it's original form?
 
wasn't there a gyro built in Canada that had servo flaps (Avian 180) in it's original form
The pictures of the Avian 180 which I have collected (see below) and two small articles do not mention any flaps. The only unusual feature was a compressed air nozzle system for prerotation that seems to have been intended for trials on one of the prototypes. I think though it has not actually been installed.
http://www.rotaryforum.com/forum/showthread.php?t=41075


too sensitive to onlookers watching with hands
Sorry JC, I didn't get that. Perhaps I am a bit over enthusiastic when it comes to discussing servo flap rotor systems, this being one of my pet ideas....;-)
 
The only real advantage of servo flaps on torsionally flexible rotorblades, Juergen, is the elimination of feathering bearings carrying a centrifugal load of several tons. Then there’s the complication of actuation linkage and the aerodynamic drag penalty.

Torsion packs also work. The UltraSport helicopter, one of the few EAB designs by professional helicopter engineers, used a hank of music wire embedded in polyurethane in lieu of rolling element bearings.

Where there’s no requirement for collective pitch, tilt head cyclic with central flap hinges is entirely satisfactory. It also can provide stabilization via offset pitch pivots.
 
You are of course right, Chuck, that the disadvantges of the servo flap rotor for a conventional (recreational) gyro are
such that no one seriously seems to consider one. What makes it attractive to me are three things:
- it is easy to incorporate a jump start capability
- the systems lends itself very well to model tests since you could attach RC controlled actuators
directly to the flaps as pointed out by Dino
- the system scales fairly easily to larger rotors since the flaps simply scale up as well and the control forces remain small
 
A tilt rotorhead isn’t satisfactory for jump takeoff regardless of collective pitch method; torque transmitted through an angle; -the tilt pivots- and the resultant component in the control system rules it out.

The larger problem is getting sufficient power to the rotor while the engine is connected to a prop.

The Cierva type machines with low speed, direct drive engines had sufficient excess of power at an RPM lower than normal operating RPM to overspeed the rotor. Modern, high speed, geared engines probably do not without de-clutching or feathering the prop.
 
You are of course right, Chuck, that the disadvantges of the servo flap rotor for a conventional (recreational) gyro are
such that no one seriously seems to consider one.

Well, I beg to differ Juergen ;)....'cause in my opinion, I do seriously believe a servo-flap controlled rotor (through a swashplate or electric actuators) has several advantages over a tilting/gimbaled rotorhead.

Advantages:

(A). Small cyclic stick actuation control forces: On a gimbal-headed, 2-bladed rotor, try holding the cyclic with the thumb and forefinger, from the start of pre-rotation through flight and until the rotor stops turning.....it is possible if you have a super strong hand.

(B). Lower rotor vibrations: One couldn't slap on servo-flaps to a standard gyro-type rotorblade and expect it to work worth a hoot. A servo-flap controlled rotorblade must not be as rigid in torsion as is required by blades that are pitched at the root or by the rotorhead. Servo-flaps that are positioned aft of the blade trailing-edge, act as horizontal stabilizers for the rotorblade and help dampen out vibrations. These blades are also easier to adjust for tracking....it's like having big trim-tabs. These blades are also easier to balance, especially in the chord-wise direction. A rigid 3-bladed rotor will have less vibrations than a semi-rigid, 2-bladed rotor.

(C). Higher pre-rotation rpm due to less lift drag: The servo-flaps can keep the blade airfoil at zero lift during spin-up and then move to positively twist the blades when ready to fly. The blade root stays locked. Because these blades can twist both positive and negative degrees while in flight (like a helicopter), I believe the airfoil should be at or near symmetrical, like 0012. Once flying straight and level, the blades have a positive twist which is similar to a Dragon Wings blade, except the in-flight adjustable tip speed can be kept close to 400 fps for less parasitic blade drag.

(D). Due to the way these blades can be controlled and how the rotorhead is designed, the airframe follows this rotor system's every movement.....like preventing rollover right after landing. Jump take-off is also within reach.....
There are more advantages but I've run out of time.....

I like and respect what Kaman designed and I think servo-flaps have a place in the newer gyroplane's.

Here is an idea of what I'm going on about.....
 

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As a true servo-flap aficionado and engineer I do of course fully agree with you Ed that technically these rotors would be great! I feel thought that people shy away from the hefty price tag for developing such blades for the gyro market. As I mentioned previously they would have to be taylor made with torsional stiffness being amongst the key design goals to meet, as you have stated, and they are more expensive to manufacture as well, with all the stuff you have to build in and attach to make the system work. The question is how many people would be willing to pay how much more for these superior blades. So far gyros have been the domain of bare bones flying and this is only slowly changing with what Chuck calls "Dreadnought Gyros". If these have seen wider acceptance and thus the whole gyro market attains a higher price level we might get to the point where there is at least a niche market for a high end product like a servo-flap rotor blade. As I said before still another matter is for a dedicated and enthusiastic team to develop blades for personal use. I currently am convinced that wood is the material of choice for home made servo flap blades. The low torsional stiffness of wooden blades would make it easier to bring the torsional frequency to the required value as published by Chopra et. al. I have started to build a FEM model for such blades although I only made some very preliminary calculations as currently my main goal is the development of my gyro stability program. Let's do hope that 2015 is a year of great progress for all of us and our pet, the servo-flap rotor blade!
 
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I know that you Juergen, have the right mental stuff to make the servo-flap rotors viable for the "Dreadnought" type gyros. Single seat gyros are served well by 2-bladed rotors and even some of the lighter two place machines squeak by. But the heavier two to four seat gyros would be much better handling and safer machines if they used 3-bladed rotors with much lower tip speeds. That would be a good niche for servo-flap rotors. Five blades would probably be better beyond four seats.....but that's not going to happen.

I do hope you completely figure this stuff out by at least the end of 2015! I quit smoking about four years ago and can no longer think worth a hoot.....so I'll not be much help.....unless perhaps I start puffing again ;).
 
I do hope you completely figure this stuff out by at least the end of 2015
Each estimate I have so far given in this forum has been so ridiculously wrong that I would actually like to delete all those posts, so no more estimates from me...;-(

But the heavier two to four seat gyros would be much better
That's what I envisage ultimately, a four seat Sedan De'Ville Gyro, something along the lines seen below swinging a 60 foot four bladed rotor....;-)
(full size available here
http://www.wallpaperup.com/wallpapers/download/170726....
from here:
http://www.wallpaperup.com/170726/1938_Rolls_Royce_Phantom_III_Sedanca_de_Ville_by_Park_Ward_luxury_retro_t.html
some more details here:
http://www.classicdriver.com/en/car/rolls-royce/phantom-iii/1937/201653

I quit smoking about four years ago and can no longer think worth a hoot
This will be a lesson to me Ed, I don't smoke but I'll think twice before I quit drinking...;-)
 

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Each estimate I have so far given in this forum has been so ridiculously wrong that I would actually like to delete all those posts, so no more estimates from me...;-(


That's what I envisage ultimately, a four seat Sedan De'Ville Gyro, something along the lines seen below swinging a 60 foot four bladed rotor....;-)
(full size available here
http://www.wallpaperup.com/wallpapers/download/170726....
from here:
http://www.wallpaperup.com/170726/1938_Rolls_Royce_Phantom_III_Sedanca_de_Ville_by_Park_Ward_luxury_retro_t.html
some more details here:
http://www.classicdriver.com/en/car/rolls-royce/phantom-iii/1937/201653


This will be a lesson to me Ed, I don't smoke but I'll think twice before I quit drinking...;-)
Best wishes Kolibri .... but never mind about Rolls Royce and all that other stuff

We are trying to control the pitch of a rotor blade by a swash plate at the root of the blade .... or an aileron midway out on the blade ... I do not know which one is the best but I like them both

But if you ever quit drinking while you are thinking I will fire you !!!!
 
if you ever quit drinking while you are thinking I will fire you !!!!
LOL Arnie,
fortunately we have some of the best beers in the world here in Duesseldorf (I don't sound too much of a local patriot, do I ?...;-), so no great risk here!
 
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