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Zenith "no hinge ailerons"

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Toobuilder

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Concerning piano hinges on a long, flexible wing - the Lockheed U-2 has piano hinges for both flaps and ailerons. The hinges themselves are standard MS extrusions with each lobe relieved a touch. The U-2 is not known for sporty handling, but the hinges survive just fine.

As a tangent to this, the upper plennum lid on the Rocket is secured to the baffles with a continuous run of piano hinges. Thought I was real clever until I found a broken lobe caused by independent movement/expansion of the cylinders. Remembering the Lockheed solution, I spent a couple hours relieving each lobe with a file. Seems to be the solution here as well
 
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Himat

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This is probably one of those things that works fine right up until it doesn't.

If you look at the (few and getting fewer) sailplanes that use an uninterrupted upper skin between the wing and the aileron or flaperon, you see that they all also use supplemental mechanical hinges that react shear between the control surface and the wing. In the absence of those hinges, you probably flirt pretty closely with flutter regimes. Given the structural complexity of the uninterrupted skin, and the mechanical complexity of having both that and the mechanical hinges, the cost probably does not outweigh the relatively tiny performance benefit. Especially since commercially available mylar seals get you most of the way there.

As it turns out, the window of utility for this innovation would probably have been wider had aggressive airfoils like those on the ASG-29 come along earlier, and had they used it on the lower skin instead of the upper skin. However, I don't think that would have made it worthwhile for anything but advanced competition, and such aircraft would probably be known for accumulating water that enters at the upper hinge gap and pools inside the hinge cove.
Many composite radio control sailplanes are made with the skin as a hinge. Do work and work at high speed. Have anybody here seen one of the DS Kinetic designs? The web pictures look like live hinges on them and a 130 Kinetic DP model was flown faster than 500mph.
 

pictsidhe

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I looked into living hinges for my project but decided against them. The infinite life living hinges need a different type of PP than that used for Coroplast. They also do not like shear loads. My surfaces will have some flex, which would have a strong centreing effect with piano hinges and would put compressive and tensile loads on living hinges due to that. I have instead come up with non-binding mechanical hinges.

It could be that living hinges could be made to work reliably and safely, but it's complex problem needing a lot more work than I'm willing to put in. The partial failure scenario also scares me.
 

litespeed

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Seems a problem in service life that should not get past the design board.

Unless this hinge method is the only possibility for a point design- I would pass.

Just use gaps seals if you must.

From a buyers prospective- I would be wary and extremely so as a second hand buyer. I could see its value drop purely from doubts of buyers.

Anything that screams experimental, unusual practice or short life span should be avoided.

Not personally a fan of Zenith products either but that is a side issue.
 

cheapracer

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Unless this hinge method is the only possibility for a point design- I would pass.


Not personally a fan of Zenith products either but that is a side issue.
It's the 'simple' factor I was looking at, if it's a real problem in service life I don't know, was it the root cause of the CH601 crashes?

I note the CH650 design is slightly different to the CH601 in that it appears to have greater length to flex with.

Plenty of Zeniths out there with lots of hours, the high wings seem robust, but Zeniths seem to be built on the borderline of minimal material though, but because of that, the designs are good for research.
 

litespeed

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As a Aussie,

The idea of a film hinge is scary even more than alloy.

Some of our wildlife love attacking slow aircraft and even have ago at tearing your skins. Hate to have a moody Eagle make a tear in the hinge as it has its revenge.

I know it sounds strange but.............were are a weird mob.

And a Wedge tail is a very big Eagle. 1/3 rd bigger than Bald Eagle.

Note damage to skin at end. I have seen vids of this same bugger- called "Jack the Ripper" attack a the same Goat glider, land on the leading edge and start pulling apart the skin in flight.

Jack does not share his airspace. Either your a meal or a threat.
 

bmcj

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As a Aussie,

The idea of a film hinge is scary even more than alloy.

Some of our wildlife love attacking slow aircraft and even have ago at tearing your skins. Hate to have a moody Eagle make a tear in the hinge as it has its revenge.

I know it sounds strange but.............were are a weird mob.

And a Wedge tail is a very big Eagle. 1/3 rd bigger than Bald Eagle.

Note damage to skin at end. I have seen vids of this same bugger- called "Jack the Ripper" attack a the same Goat glider, land on the leading edge and start pulling apart the skin in flight.

Jack does not share his airspace. Either your a meal or a threat.
Aaah, that’s just his mating ritual. Either that, or he saw the bigger Eagle with a tender human morsel in its mouth and it just wanted a piece of you for himself.
 

bmcj

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It could be that living hinges could be made to work reliably and safely, but it's complex problem needing a lot more work than I'm willing to put in
I would never consider using a living hinge, because a living hinge would eventually start thinking for itself and the next thing you know, it’s going to start demanding things like equal rights, union coffee breaks, etc.
 

cheapracer

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I would never consider using a living hinge, because a living hinge would eventually start thinking for itself and the next thing you know, it’s going to start demanding things like equal rights, union coffee breaks, etc.
I believe your term "living" hinge to be offensive to dead, non-operational, and discarded hinges, please try to find a more gender neutral term thank you.
 

anvegger

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Interestingly the CH approach is well defined


And no problem have been detected with that hingeless design for years. Problems became noticeable when people started asking for hinge based ailerons. The hingeless aileron design have been known in European design way before the WWII - from 30-s if not 20-s. Many Soviet airplane designers have used that approach.
 

cheapracer

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Would that create a stress concentration between each pin segment? Would it matter?
Technically, probably, but the stress is so low on a piano hinge that it wouldn't matter. That's a full aileron width piano hinge of course..

The EAA recommend using 3 x 6" lengths of piano hinge if you think full width binding will be an issue.
 

Vigilant1

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It's the 'simple' factor I was looking at, if it's a real problem in service life I don't know, was it the root cause of the CH601 crashes?

I note the CH650 design is slightly different to the CH601 in that it appears to have greater length to flex with.
Just to clarify:. It wasn't the Zenith 601 that had all the problems. It was the Zenith 601XL. The wings are different between the two designs. The 601 has had a long history of safe flying, and it does use the hingeless ailerons (though many owners fit hinges). I would prefer hinges. Good control feel is an important attribute in a fun-to-fly plane, and these ailerons detract from it. If I were building a utilitarian little cargo hauler and wanted simplicity of build above all else, I could see the attraction.

The Zenith/Zenair model names are not as clear as they could be, (IMO)
 
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stanislavz

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BBerson

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What is the problem? Fatigue life 120,000 hours (post 31).
By the way, cutting piano hinges to 6" segments won't prevent binding if the wing bends up in flight. In that case the aileron must be segmented like a Schweizer 2-33.
 

cheapracer

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What is the problem? Fatigue life 120,000 hours (post 31).
I think it's the mindset I referred to earlier, who hasn't flex a material back and forward a few times and had it fail.

Boku has a solid point though, the 'hinge' can move in a vertical plane, a hinge certainly can't.

During flutter it must be a crazy scene with that extra axis of movement.
 
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