Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by rtfm, Dec 28, 2010.
Hi Bro..... How are you going so far with your wing folding construction?
If you are talking to me, the answer is it's going to be awhile. I'm focusing on populating the cockpit section with stuff like controls, skin attach points, canopy frame, etc. I might even built the aft fuselage next. That way I'll have the weight and balance data to better locate exactly where the wing attach will be, which will determine where to put attach holes in the wing spars. Everything so interrelated. The key is determining the critical path/sequence of design and build.
Oh i see Geschwarz....its a lot of work to be done, actually am asking RTFM.
I am designing a folding wing for my buddies plane. he sent me pics of this design very simple and easy to install. it should work well withg what you want to do. i can send you detail drawings when i get it adapted to his plane... lester
I can't let this opportunity go by to point out that Eric Clutton has been flying his folding wing FRED design for almost 50 years now, so the mechanism has proven the test of time. FRED is a semi-cantilever design so it may not be entirely applicable, but perhaps worth a look. Here's a quick detail shot taken from this photo album (on my site): Eric Clutton's FRED
Not a homebuilt but the RWD-8 RWD-8 - Wikipedia, the free encyclopedia had folding wings. If I remember the wings fold back like a fly's; one wing had a what looked like a flap but it was flipped up or down so the trailing edges did not meet. I think it was used for small cargo compartment also. It is a good looking airplane too.
That's pretty much the same mechanism as the Stemme S10 has.
Assuming that you only want to shorten the span for a standard 3 meter garage door you don't need to remove much. If you want to shorten to whatever a legal trailer width is in Oz that is another story.
My take is that even if you cut your wing off at a standard 2 meter trailer width and you put stub spar extensions on the removed wings (like a glider) that the outer wing panels wouldn't weigh enough to be worth folding. One person could handle taking them off and stowing them in a garage or trailer. Much simpler than folding and more robust and then you are down to copying a stub spar design and an aileron quick connect which have strong examples to copy also.
What is the goal of folding? Do you wish to drive the thing down the road to a house from the airport? If not there is really no need for folding. Just put two saddles on the trailer and take the outer wings off for transport. I did that with my design. It is set up to have the outer wings with outer flap half and ailerons removed with the inner flaps staying with the fuselage. That way the aircraft stays on gear and is taxiable and can be driven up on a trailer and is narrow enough to be transported without any other derigging. Get to airport, put on wing extensions, put in one pin each side and everything else: lighting wires, aileron torque tubes, flap pass through, (and potentially outer fuel tank connections), hook up automatically. That is all fairly straightforward.
Keep your gear stance narrow enough to get on any trailer you want to use and keep the derigged aircraft narrow enough to get through any door you want to go through and you are in good shape.
I have seen several designs that do just that, but leave the wing attached somehow via a fitting which is not load-bearing in flight. Why bother? Well, the great thing about gliding and it's Achilles heel is that it is essentially a group activity. Assembling a glider all by yourself it at best awkward, requiring little stands and things to make up for the extra hands, and in some cases impossible. The best wing-folding arrangements also make it much, much easier to so single handed. Eric Clutton's FRED above uses one approach. The most elegant system I have ever seen is that used on later Henri Mignet tandem-wing designs, but I suppose that's cheating as they don't have any ailerons to worry about.
Your comments are dead-on. I can easily lift the wings of many gliders, even though I'm not particularly strong. But their sheer size is usually preventing this.
I'm working on a folding mechanism for my own too. I'm basically using the glider-approach. On the ends of my spar stubs, there's a flexible coupling that connects to a rails that runs left/right. This rails is just strong enough to take the vertical weight of the wing. When you pull the bolt that connect both spar stubs, the wings will "fall" a bit and the spar stubs will rest to a block above their ends, taking the wing mass. When you lift the wingtip, you can pull out the wing and if it's rolled out to the wing/fuselage fairing, then you can walk it to the back and suspend it there.
Thanks for all the input, examples, pictures and suggestions. But I'm thinking that with each wing only about eight feet in length, it might just be easier to remove the entire thing. It should be easy enough to do. The spar stub passes through the strengthened fuse, with the end attaching to a central fixed point. I won't be able to slide the spar stubs alongside each other and fix them with a couple of pins the way so many planes do, because my wings are both tapered (3:2 ratio) and swept (7.5 deg) so the spars don't line up. But with each spar attaching at two points, it should be easy enough to release them.
And the half wings will be pretty light also. I just have to figure out an idiot-proof way to connect/disconnect the control linkages. The flaps will be electric, so that's simple enough. But the ailerons are a bit more complex.
Thanks again guys,
I wish he mentioned how the ailerons were attached Folding Wing Brackets
This is an old thread. I would like to add a question here about aileron cable for foldable / removable wings.
I am designing my own Pt 103 with wood and fabric and already have the folding mechanism (spar attachment and strut fittings) worked out.
It will be a removable wing, ( not a folding one. )
My challenge seems to be the aileron cables.
Not able to figure out how to handle that part of the removal.
Any ideas on this will be appreciated. Thanks
Have a good read through this post before you commit to anything:
That topic discussed various mechanisms.
The classical sailplane hook-up seems to me like a good option; have the cables terminate in a crank, which locks into a crank on the inside of the wing.
Fairchild had a nifty way of handling that on some of their early planes - think it was the FC-1 or FC-2. Basically, two vertical flat paddles/pieces of metal vertically pivoted in the middle. Each piece pressed against each other when in flight mode. One piece on the wing, one piece on the fuselage. A slick set up. Hard to describe. There's a picture of the wing fold in the link above, but there should be more pictures somewhere on the net.
That setup has various issues. Wear and tear quickly result in aileron flutter. Ideally alignment and actuation axis are different.
My solution would be push/push linkage to the aileron that would just fit together when you put the wing back.
I have gone over to the "dark side" on this (which means that AR is giving good advice again, and I'm taking it).
I just wish there was a simpler and less expensive way to do the mechanism.
A rotating assembly with torque tubes is really simple and safe. Routing the cables vertical at the joint and you could do the same thing.
With the "sailplane connection", you can also go for such a push-push pad, simple make it t-shaped, outward on the outboard wing and inboard on the inboard wing and let them slide over theirselves. That avoids the potential for play and thus flutter etc.
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