The flaperon section is connected to an arm on the carbon fiber bellcrank by a short push-pull tube. I couldn't show that in this video because the mold surface is in the way.
Internal aileron linkage
- Thread starter Scheny
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OK, I just got it. This translates the linear movement of the pushrod into rotation and the weight rotates around an offset axis that has an identical moment to the flap. The up and down was confusing me without seeing the flap. Is the flaperon horn or horns conventional, as in non skewed actuation?
I will use this in the future for a bunch of things. Sort of like a lot of the little universal joints in a lot of landing gear legs to rotate the leg while retracting. You can never have a large enough library of solutions available.
I will use this in the future for a bunch of things. Sort of like a lot of the little universal joints in a lot of landing gear legs to rotate the leg while retracting. You can never have a large enough library of solutions available.
geraldmorrissey
Active Member
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- Aug 11, 2008
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- 38
Torque tubes. Mount the aileron to the tube, arrange bearings on the rear spar, devise a control system to twist the tube. Used quite successfully on the Stephens Acro and probably others.
Correct, the flaperon drive from the bellcrank to the horn on the upper surface of the flaperon is entirely conventional. Using a skew drive for the flaperon would have required center-hinging the flaperon, which would have been more trouble than I wanted. I used the skew drive for the mass balance because it was the simplest way to implement something that lives inside the wing and works well for decades on end.
Torque tubes are great for short distances where you have volume for a tube with lots of enclosed area. For longer distances they are fairly poor in terms of stiffness per unit mass.
The torque tube ailerons in the Stephens Akro were replaced with push-pull tubes in the Extras (and other one offs). Lighter, and tighter, but look dorky in the cockpit.
BJC
BJC
pwood66889
Well-Known Member
The Ercoupe uses push-pull tubes to actuate the ailerons. They go from the "mixer" where the rudder cables take off, through the stub wing at a funky bell crank, then to the aileron. Need a picture?
I purchased plans for the CH701 and CH750 aircraft. They use flaperons.
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pictsidhe
Well-Known Member
Weren't we discussing aileron linkages?
No we weren't.
But I thought that was the question being asked.
Scheny
Well-Known Member
This is how it is done in the Cirrus. Quite similar like the Libelle, but actuated by pulleys, which rotate the red shaft around the center axis of the pulley disc. Due to that, it needs an additional axis (blue).
Does anyone have more pictures of ailerons similar to the Libelle?
Scheny
Well-Known Member
@BoKu there are good linear slide bearings available from IGUS that I am planning on using. This one is for 5/8 (16mm) and can be clipped onto 3mm strong carbon panels:
I used the IGUS products for the steering of my boat, where I have a sidestick acting on a torque tube which is supported by two of these bearings. Slides almost without any noticeable resistance and needs no service at all. I heard that a lot of aircraft already use these products.
I used the IGUS products for the steering of my boat, where I have a sidestick acting on a torque tube which is supported by two of these bearings. Slides almost without any noticeable resistance and needs no service at all. I heard that a lot of aircraft already use these products.
That's a big parts count to save one horn and a tiny fairing. What advantage does that give? The flap hinges are hang out in the breeze already anyway.
pictsidhe
Well-Known Member
If using Igus, be careful to pick the right material. They have a pretty good online selector and are extremely helpful if you email them. The wrong material can be very disappointing
TFF
Well-Known Member
I think the Cirrus is done that way to keep a the controls in the wing cove instead of having holes in the tank that have to be dealt with which would be way more complicated. It’s done like a big plane which is a nice touch.
If that's why that's a good compromise. Breaking into a composite structure for access to controls is always a tough design problem. If stuff can be bolted on outside it is always better.
Click on the video. It shows how the CH701 uses push rods and ball cranks for it's aileron control
