Aileron Hinge Design

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Dana

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Also download and study the plans for the Minimax and Bloop ultralights (both are free) to see how they did things.
 

cheapracer

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Ultralights are not flown in the rain and will not last long if left outdoors.
Piano hinges are used on a wide variety of aircraft that get rained on, washed, and left outdoors.

Because virus in China, I am carrying a small bottle of, and using rubbing alcohol 5 to 10 times a day, it evaporates within mere seconds, and leaves no water residue to be concerned about.
 

Victor Bravo

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I fly one of the airplanes that uses piano hinges on the ailerons. It is a very stiff, fully "sheeted" aluminum wing (Cessna 172) which has no visible flexure in flight. The forward and rear spars are solid C-channel beams with a shear web in between the upper and lower caps. The aileron is a full upper and lower skin with a C-channel spar at the front, and it is very stiff as well. The ailerons are about 8 feet long, and are operated by cables and bellcranks. The portion of the wing occupied by the aileron (connected by piano hinges) is perhaps half the span. In normal flight, for all practical purposes, nothing moves more than a small invisible fraction of an inch. So the piano hinges don't bind.

The Kolb Firestar LSA I flew for several hours had a light weight aluminum tube for the trailing eedge spar, as well as the leading eedge of the aileron. Neither the wing trailing edge spar, nor the aileron, had any vertical shear web in it. Even the main spar only has a short 8 or 12 inch sectiton of shear web at one location mid-span. The aileron and torque tube assemblies are 12 feet long.The portion of the wing span occupied by the aileron and its integral torque tube (and connected rigidly by sections of piano hige) is 95% of the wing span. Under normal 1G flight loads I am guessing that the wingtips are raised 3-4 inches above their position on the ground. In a turn this will increase a little more.

On the Kolb Mark 3 I flew with a friend, and on the Kolb Firestar I flew briefly, as an experiment I had two people lift up on the wingtips with their estimate of ten pounds of force each... far far far below the equivalent lifting force in flight. The force required to move the stick went from almost nothing to "what's wrong with this airplane???" instantly.

Yes, there are tousands and thousands of airplanes that use piano hinges without any problem. They can use the piano hinges only because there is no significant wing flex in flight.For Ollie's ultralight, and any other airplane using long sections of round tube for the wing spars and beams, piano hinges are much much more likely to cause problems. For very little gain compared to other hinge methods.

Just building a wing with the hinges attached to round tubes, and getting the hinge axes all lined up, is a nightmare. Riveting flat extruded hinge sections to round tubes, without the hinge sectiton "rocking" on the tubes, is a nightmare. Hammering and forming the hinges to a rounded shape to cup the tubes is a chore. Drilling out 100 pop rivets (with mandrels that require a punch) on a Kolb to remove an aileron and torque tube is a friggin' nightmare (trust me).

Homer Kolb did a lot of clever things. But his aileron hinge method is not one of them.
 
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Aerowerx

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There is a special place for him, where it's very warm. A blessing and a curse!!!
The original autocorrect was for Microsoft Word. It corrected common typing and spelling mistakes. Like "teh" and "seperate".

What we have now on Smart Phones is downright evil. It thinks I know what I want to say better than I do. Then I have to send an amended text with the desired word.
 

cluttonfred

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Back to the topic...there are some interesting tidbits in these articles on control systems by Tony Bingelis and others here: https://www.eaa.org/eaa/aircraft-building/building-your-aircraft/while-youre-building/building-articles/control-systems?

For example, from one of those articles, here is a very simple design made from three (or four) sections of aluminum angle, a bolt, a castle nut, and a cotter pin. Of course, you'll also need rivets or bolts to attach the angles to the wing and the control surface.

You can imagine this working well with wood, composites, sheet aluminum, or square aluminum tube. You could choose to use steel angle (with some lightening holes) for more strength and less concern about wear, but that could also be solved with regular inspection for any play.

PS--Come to think of it, hinges like that could be mass-produced from aluminum or steel angle on a little CNC setup, complete with cutting lightening holes and snipping off the corners near the hinge bolt hole to minimize weight.
6ControlSystemSavvy-1 (detail).gif
 
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Dan Thomas

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I fly one of the airplanes that uses piano hinges on the ailerons. It is a very stiff, fully "sheeted" aluminum wing (Cessna 172) which has no visible flexure in flight. The forward and rear spars are solid C-channel beams with a shear web in between the upper and lower caps. The aileron is a full upper and lower skin with a C-channel spar at the front, and it is very stiff as well. The ailerons are about 8 feet long, and are operated by cables and bellcranks. The portion of the wing occupied by the aileron (connected by piano hinges) is perhaps half the span. In normal flight, for all practical purposes, nothing moves more than a small invisible fraction of an inch. So the piano hinges don't bind..
Those Cessna wings flex more than one realizes. Most changes in loading are slow, so we don't notice the movement. I learned to fly floats in a Cessna 180, and step-taxiing across choppy water at 40 MPH would get those wingtips going up and down nearly three inches. The lead mass-balance weight on the outboard end of the aileron contributes to that, and that outboard piano hinge (on all Cessnas, not just floatplanes) suffers vertical wear and the center hinge, which is at the aileron pushrod loaction, suffers fore-aft wear. Floatplanes wear out stuff faster.

The ailerons flex a bit to follow the wing. They are more flexible vertically than horizontally, but they do flex.
 

Dan Thomas

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Back to the topic...there are some interesting tidbits in these articles on control systems by Tony Bingelis and others here: https://www.eaa.org/eaa/aircraft-building/building-your-aircraft/while-youre-building/building-articles/control-systems?

For example, from one of those articles, here is a very simple design made from three (or four) sections of aluminum angle, a bolt, a castle nut, and a cotter pin. Of course, you'll also need rivets or bolts to attach the angles to the wing and the control surface.

You can imagine this working well with wood, composites, sheet aluminum, or square aluminum tube. You could also choose to use steel angle (with some lightening holes) for more strength and less concern about wear, but that could also be solved with regular inspection for any play.

PS--Come to think of it, little hinges like that could be mass-produced from aluminum or steel angle on a little CNC laser setup, complete with cutting lightening holes and snipping off the corners near the hinge bolt hole to minimize weight.
View attachment 93805
That might be fine for something that has very light loads and doesn't fly a lot. Aluminum angle is typically 6061 and is rather soft, and some bronze bushings would be a good idea. The bolt in the aluminum can also corrode quickly; dissimilar metals produce galvanic action if they're wet.

The Jodel had hinges folded up from 4130 sheet, with the control suface half fitting between the legs of the fixed half. The control suface half had a steel bushing welded into it, and a 1/4" bolt or clevis pin held them together. Rust was a problem. Oiling them would help temporarily, but the weather cleaned that out soon.
 

cluttonfred

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I agree it's not a heavy-duty solution, but it seems like an appropriate option for a tube-and-fabric ultralight. I wonder if there would be any simple ways to mitigate your concerns...such as 4130 steel angle brackets and a mild steel tube as a bushing? I was trying to find a simple solution, hackswaw and drill and no welding, given the application.
 

Pops

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Those Cessna wings flex more than one realizes. Most changes in loading are slow, so we don't notice the movement. I learned to fly floats in a Cessna 180, and step-taxiing across choppy water at 40 MPH would get those wingtips going up and down nearly three inches. The lead mass-balance weight on the outboard end of the aileron contributes to that, and that outboard piano hinge (on all Cessnas, not just floatplanes) suffers vertical wear and the center hinge, which is at the aileron pushrod loaction, suffers fore-aft wear. Floatplanes wear out stuff faster.

The ailerons flex a bit to follow the wing. They are more flexible vertically than horizontally, but they do flex.
Yes the Cessna wings flex. At 11K in a C-172 at cruising speed I hit turbulence while I was looking out below the left wing. Knocked the breath out of me, hurt my back. Saw the wing tip flex several inches and even the wheel pants shook, also the windshield made a loud popping sound. LE of a strong cold front in Nov.
 

Dillpickle

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Yes the Cessna wings flex. At 11K in a C-172 at cruising speed I hit turbulence while I was looking out below the left wing. Knocked the breath out of me, hurt my back. Saw the wing tip flex several inches and even the wheel pants shook, also the windshield made a loud popping sound. LE of a strong cold front in Nov.
I used to fly commercial more than I liked. I always picked a wing window seat--the center of the See-Saw. A 747 or air bus, fully loaded with fuel, will have the wing tips drooping many FEET below its empty weight. Upon take off, the wing tips bend up to 12 feet higher than the at rest position. I derived some perverse pleasure pointing the movement out to other passengers and asking, "is it supposed to do that?"

Here are some tests with videos for our young student--I wonder what these guys do to keep flaps and ailerons from binding...
https://www.popularmechanics.com/flight/g2428/7-airplane-wing-stress-tests/
 

raymondbird

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Belleville, Ontario Canada
I agree it's not a heavy-duty solution, but it seems like an appropriate option for a tube-and-fabric ultralight. I wonder if there would be any simple ways to mitigate your concerns...such as 4130 steel angle brackets and a mild steel tube as a bushing? I was trying to find a simple solution, hackswaw and drill and no welding, given the application.
Could this work . . . ?
 

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Ollie Krause

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Feb 26, 2020
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Also download and study the plans for the Minimax and Bloop ultralights (both are free) to see how they did things.
The MiniMax plans seem to cost some money but I got the ones for the Bloop for free and they look super detailed. I also purchased the Affordaplane plans a bit ago so I've been reviewing those as well. Thanks for the suggestion!
 

Ollie Krause

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Just building a wing with the hinges attached to round tubes, and getting the hinge axes all lined up, is a nightmare. Riveting flat extruded hinge sections to round tubes, without the hinge sectiton "rocking" on the tubes, is a nightmare. Hammering and forming the hinges to a rounded shape to cup the tubes is a chore. Drilling out 100 pop rivets (with mandrels that require a punch) on a Kolb to remove an aileron and torque tube is a friggin' nightmare (trust me).

Homer Kolb did a lot of clever things. But his aileron hinge method is not one of them.
So it sounds like creating U bracket hinges riveted to the aft spar are just going to be too complicated to manufacture and piano hinges are too prone to binding. I'm going to do a quick mock up of a design using a torque tube with nylon bushings and I'll put some screenshots here when I'm done. I was thinking that if I make the torque tube just slightly longer than the aileron, only leaving enough extra length to fit into the bushings and attach a bellcrank, it will be more rigid and less likely to lock up from any bending during flight.

On a completely separate note, unfortunately due to wind, our EAA Young Eagles fly day was canceled today so I won't have a chance to check out some ailerons until Sunday the 8th. The chapter which is hosting the event is: EAA Chapter 1232 at Marin County Airport if anyone here is local to the Bay Area or a member. Thanks again for all of your support!
 
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