Folding Wings, Aircraft Trailers, and Portable Hangars for Inexpensive Storage

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Hot Wings

Grumpy Cynic
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Probably prohibitive on a 103?How much does it cost to make/buy/install those parts?I really like the concept, but am concerned it's not possible in 103?
The Sadler Vampire had a wing fold and mostly metal construction 30 years ago. Some of the features of that particular folding arrangement aren't in agreement with what has been presented here as "best practice" but it proves that a true part 103 weight with folding wings can be done.

Sadler Vampire promo video - YouTube

Note: Not the ultralight version, but the same folding mechanism. It could be improved upon IMHO.
 

Rienk

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The Sadler Vampire had a wing fold and mostly metal construction 30 years ago. Some of the features of that particular folding arrangement aren't in agreement with what has been presented here as "best practice" but it proves that a true part 103 weight with folding wings can be done.

Sadler Vampire promo video - YouTube

Note: Not the ultralight version, but the same folding mechanism. It could be improved upon IMHO.

The problem is that, regarding weight, we'll get nickled and dimed beyond the limit.
My take is that we have to work backward.
If a UL is to see a mass market, I think it needs to retail for $15-19k - which means it needs to be manufactured for less than half of that. There's just not a lot of room for fancy systems.
It needs to be four-stroke, and look sexy (the Sadler is the best at that, IMO).
It's already very difficult to build a true ultralight with a four-stroke, let alone an inexpensive industrial engine.
Adding a bunch of extra fittings, connections, and hardware will likely put it out of the running.
I want it to work, I just don't know how it will...
 

Hot Wings

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NOTE: This is a deliberate double-post, from the HSA Tehachapi thread. Same subject is being discussed in both, with the same positions being held.
I think we've actually been discussing the folding wing option of 3 threads. I started this thread in the hopes that we could leave the cheaper aircraft are impossible thread to other aspects of getting more aircraft built and used.

I think that we have a pretty good list of the features that a good folding system should have. Now I think it's time to start posting examples of existing art so that we can all see what is available now, and maybe give us some inspiration to improve the situation.

Gliders seem to have a pretty good handle on the problem. For now I'd like to discuss trying to move that technology over to the ultralight/LSA class of plane, and maybe improve it if we can. Gliders are by their very nature with high AR wings "stuck" with long trailers or multiple wing sections. Ultralights and LSAs with shorter wings may allow us to package them into a box that is more likely to be able to be towed on the highway in wind and stored in the home garage with ease. I see the trailer and the wing fold as a package deal where the design of one effects the design of the other.
 

Hot Wings

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It's already very difficult to build a true ultralight with a four-stroke, let alone an inexpensive industrial engine.
Adding a bunch of extra fittings, connections, and hardware will likely put it out of the running.
I want it to work, I just don't know how it will...
The 4 stroke is going to be the hard part. The weight penalty for the folding mechanism on the Vampire is probably in the 2 pound range over the same plane with a fixed wing. Saving enough weight in the rest of the structure for a 4 stoke industrial would be hard to do. But that problem is for another thread.
 

mcrae0104

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My concern isn't slop itself, but the potential for flutter. Murphy's law is all too valid and too many people have already be killed by designs like this. Theoretically it's perfectly fine, but in an operational environment it's a recipe for disaster. You're pushing against an elastic spar, elastic fitting and a wing that moves fwd/aft. You're essentially basing your fitting on what in flight is structure that's continously moving around.

There´s a good reason all sailplane manufacturers have converged to only a single design and more than a few pilots have paid with their lives with those lessons.
So you're saying that the opposing-paddle control system has been tried, and deaths resulted? I wasn't aware of this. Which aircraft type(s) did this happen in? (Not trying to be argumentative, just wanting to learn and avoid mistakes that have already been made.)

The slop doesn't appear all at once, right? A simple preflight check of lateral stick play with the ailerons locked should reveal any slop. As soon as any creeps in, adjust the nubbers. As for the elasticity of the system, how could this system be any worse than a typical bellcrank attached to a spar or rib? Granted, all of the members need to be designed for proper stiffness based on the loads in the control system, but I'm just not seeing the fatal flaw here.

Andy
 

Topaz

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So you're saying that the opposing-paddle control system has been tried, and deaths resulted? I wasn't aware of this. Which aircraft type(s) did this happen in? (Not trying to be argumentative, just wanting to learn and avoid mistakes that have already been made.)

The slop doesn't appear all at once, right? A simple preflight check of lateral stick play with the ailerons locked should reveal any slop. As soon as any creeps in, adjust the nubbers. As for the elasticity of the system, how could this system be any worse than a typical bellcrank attached to a spar or rib? Granted, all of the members need to be designed for proper stiffness based on the loads in the control system, but I'm just not seeing the fatal flaw here.

Andy
I don't think it's so much a "fatal flaw", and certainly there have been folding-/removable-wing aircraft that have used the opposing-paddles system. If I'm not mistaken, the Europa is one, or at least it was when it first came out. I don't see those falling from the sky so, yes, it can be done.

The point Autoreply is making, as I see it, is that if you can avoid the need for a preflight check for this, wouldn't that be better? Yes, we're all supposed to preflight before every flight. Everyone here does a thorough preflight before committing aviation, every single time they fly. Right? Right?

Fact of the matter is, people skip preflight. Sometimes once in a blue moon, and sometimes they make a regular habit of hopping in the cockpit and taking off. Is it dumb? Yes. Is it going to bite them someday? Absolutely. Is it the designer's fault? Not in the least. Will a jury care, at the liability suit brought by the bereaved family of the late, great, complete idiot pilot who skipped all his preflights and got himself killed when the system eventually developed lots of slop? Nope.

Is there really any excuse for designing your control hookups such that they require a preflight inspection, when you know beforehand that there's a mechanism that can work without that diligence and more-reliably do the job?

No, not really.

IMHO, any system that can reliably do a job without being diligently inspected is better than one that can reliably do the same job only if inspected, even if you put that inspection on a checklist. Don't give the failure an opportunity to happen at all, if you can.
 

mcrae0104

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IMHO, any system that can reliably do a job without being diligently inspected is better than one that can reliably do the same job only if inspected, even if you put that inspection on a checklist. Don't give the failure an opportunity to happen at all, if you can.
I agree heartily. I guess I still don't understand the mechanism AR is advocating based on the photos and videos. (Wing attach mechanisms, crystal clear; control mechanisms, not so much. Maybe I'm slow:) ) Also, I'd like to hear of some real-world failures of an opposing-paddle system before I dismiss it on the basis of the possibility that flutter might develop due to the possibility of slop, which shouldn't crop up all of a sudden in a well-designed system. If there are some failures, we'd all benefit from knowing why they occurred.
 

cheapracer

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I hate to see the conversation bog down in such minutiae, .
I see what you did there! :gig:



The slop doesn't appear all at once, right? A simple preflight check of lateral stick play with the ailerons locked should reveal any slop.
You are presuming people would care.

/////

Very informative thread by the way about the other side of owning aircraft.
 

autoreply

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I understand how the wing spar overlaps work (though I've not learned how to make those composite ends fit precisely in a tunnel).I don't understand how pictures 4,5 and 7 work for the controls - it looks like they are incomplete at the moment?
Could you quote next time? It's hard to make out which pics you're referring to, but I think you're talking about these:
Can I ask anybody who's serious about designing them to read those two documents. Well, just look at the pictures in them:
Both dead:
http://www.onderzoeksraad.nl/uploads/items-docs/493/2008011_2006034_PH-626_Valkenburg.pdf

Miraculously survived
http://www.onderzoeksraad.nl/uploads/items-docs/773/2009048_PH-1108_definitief.pdf



The other end, although this is an HP24. Note that one automatic connector still has to be installed.



Compare to 1st picture
The upper picture shows that the rear push tube is assembled, the front one still needs it's automatic connection. The lower picture shows the not assembled push tubes arriving from the wing (wing mounted on fuselage). The triangular receptors "catch" the triangular connections on the wing. The receptors you see in the fuselage are steered via a push tube, that connects to the half-round lug you can see just underneath it.

By putting the hinge point at the same place, any translation of the wing that's less than 1/4" has zero net effect on the position of the control surface.
To me, the most important question is, how much does the wing fold and auto control apparati weigh? Probably prohibitive on a 103?How much does it cost to make/buy/install those parts?I really like the concept, but am concerned it's not possible in 103?
Virtually zero on all questions I'd say. Mostly dependent on your concept (wing position, type of tail). For an unstrutted, one-piece high wing you might very well have a lighter structure as any other 103 ultralight. Use flaperons and you've just cut complexity in half ;)
So you're saying that the opposing-paddle control system has been tried, and deaths resulted? I wasn't aware of this. Which aircraft type(s) did this happen in? (Not trying to be argumentative, just wanting to learn and avoid mistakes that have already been made.)
I can't recall. It came up in a discussion with some akafliegers a few years ago. One of the early sailplane had it and fluttered spectacularly.
The slop doesn't appear all at once, right?
Well, it can. The wing moves around in flight. Turbulence, fwd lift components, gusts. All that is extra movement and you will NOT get that out of the system. Mechanically it's the same as a non-tensioned wire control. Remember all those Zenith's that suddenly dropped out of the sky?
As for the elasticity of the system, how could this system be any worse than a typical bellcrank attached to a spar or rib?
If you have a typical bellcrank, any deformation in the wing's structure will change the position of the aileron. It won't give it free travel.

The push-push system might fly perfectly fine, even if you're f*cking up the regular adjustments. Let's say you've just taken out the slop and you've flown a thousands hours happily around. Now you pull up at 3G and Va and you hit a small gust. Due to the instant 4G the wing bends fwd, introducing considerable play. Even below LL, a quick ballpark shows that's plenty of play in the aileron to let the now loose aileron flutter.

It really is a fatal crash waiting to happen and the push/push scheme is fundamentally flawed.


The RF5B also has an interesting system. One could copy it directly to the Sonex (and fix the locking mechanism there too).
http://www.onderzoeksraad.nl/uploads/items-docs/493/2008011_2006034_PH-626_Valkenburg.pdf
 

autoreply

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This is roughly how I would do it for low/mid wings:

Use a single locking pin, no "stuff" like fuel tanks in the wings, single controls (flaperons) and bolt the wing tips directly to the tail, instead of making up an inpractical cart. (this requires beefing up the extended shaft such that they can take the weight of the wing root)
 
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X3 skier

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Folding via the primary load carrying structure in flight. Leave it outside with a bit of the right wind and it'll tear out those holes easily. If not, a local kid will do it. You won't notice it till the wing let's go.
Or just imagine what happens when I put the slightest load on the leading edge. Indeed, now your spar is bent and probably buckled.
Just curious why a design stressed for +6, -3gs would be so susceptible to gusts on the ground with the wing down and locked.

Cheers
 

Aviator168

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This is roughly how I would do it for low/mid wings:
[video=youtube;W7GsVAZl3WM]http://www.youtube.com/watch?v=W7GsVAZl3WM[/video]

Use a single locking pin, no "stuff" like fuel tanks in the wings, single controls (flaperons) and bolt the wing tips directly to the tail, instead of making up an inpractical cart. (this requires beefing up the extended shaft such that they can take the weight of the wing root)
How about high wing with weigh shift control through a stick. No flaps(or electric flaps), no ailerons.
 
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autoreply

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Just curious why a design stressed for +6, -3gs would be so susceptible to gusts on the ground with the wing down and locked.
Inertia, though my comment was about the folded wings. +6 is orders of magnitude more load, but if you for example look at that Sonex, those wings can move around a lot when up. When in "flying mode" there shouldn't be a problem. But I maintain that you always want to have non-load bearing parts that do the folding. More than a few joints like on the RF5 got damaged. That's just a replacement, but you're not always likely to see it. Then it's a funeral.

How about high wing with weigh shift control through a stick. No flaps(or electric flaps), no ailerons.
Can't tell you whether weight-shift via a stick is viable.

But for a high wing, a single-piece wing where the flaperons are attached like SH connects their tails:
Pull, not push. See around 4 minutes in this video:
[video=youtube;WRhCO42zuzA]http://www.youtube.com/watch?v=WRhCO42zuzA[/video]
Seems about as simple as it gets. Have a telescope "guider" and a spring that can lift up your wing, then rotate. That's two additional parts and maybe half a pound for adding folding. Trailering won't work very well (wings too high), but for hangare it's as simple as it gets.
 
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gtae07

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Could you quote next time? It's hard to make out which pics you're referring to, but I think you're talking about these:

The upper picture shows that the rear push tube is assembled, the front one still needs it's automatic connection. The lower picture shows the not assembled push tubes arriving from the wing (wing mounted on fuselage). The triangular receptors "catch" the triangular connections on the wing. The receptors you see in the fuselage are steered via a push tube, that connects to the half-round lug you can see just underneath it.

By putting the hinge point at the same place, any translation of the wing that's less than 1/4" has zero net effect on the position of the control surface.
Ok, I think I see how this connection works. Let me see if I get this right:
The inboard receptors normally pivot about the same axis as the triangle on the wing (i.e., the lower inboard pin on the gray wing-mounted bracket). But the actual pivot point is on the little fiberglass tab attached to the gray rod that runs underneath everything. This allows the pivot point to float with the wing's pivot point.

Now, the questions:
Do the push tubes that connect to the lug on the receptor come upwards on each side (from the bottom of the fuselage) or outwards from the middle?

How does this system accout for rattling of the wing connector inside the receptor? That is, what keeps the end of the wing connector (it looks to have a roller of some kind?) captured inside the receptor without slop? Is the straight "box" section on the connector closely tailored enough to the roller, and the roller projects far enough into it, that variances in insertion depth don't matter (the roller is still in the box) but it can't move up and down within that box?




Just s a historical note, Grumman has used the paddles on more than one aircraft. For example, the E-1 Tracer has a paddle on the forward spar, directly in line with the large attach lugs that lock the wing in place. The axis of the paddle is parallel to the locking pins, and the paddles are located near the locks themselves to minimize slop and rigging changes with structural movement. This may or may not have appliciability to light aircraft.
 

autoreply

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Ok, I think I see how this connection works. Let me see if I get this right:
The inboard receptors normally pivot about the same axis as the triangle on the wing (i.e., the lower inboard pin on the gray wing-mounted bracket). But the actual pivot point is on the little fiberglass tab attached to the gray rod that runs underneath everything. This allows the pivot point to float with the wing's pivot point.
Yep.
Now, the questions:
Do the push tubes that connect to the lug on the receptor come upwards on each side (from the bottom of the fuselage) or outwards from the middle?
Bottom.
How does this system accout for rattling of the wing connector inside the receptor? That is, what keeps the end of the wing connector (it looks to have a roller of some kind?) captured inside the receptor without slop? Is the straight "box" section on the connector closely tailored enough to the roller, and the roller projects far enough into it, that variances in insertion depth don't matter (the roller is still in the box) but it can't move up and down within that box?
Yes. This is the raison d'être for this system.
It's impossible to get a perfect wing fit every time (if only due to thermal elongation). The 3 types of misalignment you can have (wing bending, spanwise "sliding" of the fitting and fwd/aft bending (fwd lift component)) all result in zero play in the controls.
Just s a historical note, Grumman has used the paddles on more than one aircraft. For example, the E-1 Tracer has a paddle on the forward spar, directly in line with the large attach lugs that lock the wing in place. The axis of the paddle is parallel to the locking pins, and the paddles are located near the locks themselves to minimize slop and rigging changes with structural movement. This may or may not have appliciability to light aircraft.
By placing them right on the spar, you loose most of the potential for play (not everything). Pre-flights by professionals on every single flight (and probably some pre-tension on the mechanism) probably make it safe enough.

I'd still much prefer the RF5 system for a simple hinged wing:


Just don't use such a locking mechanism.
 

Holden

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A few comments...

Both videos show a very slow process that just eliminated 95% of the customers. It has to be push button easy and on the run (< 35 mph).

The issue is that when you land and are still rolling, how do you fold the wings in motion? Fighters do it...

If you don't have a hinge that takes a flight load then how can it be folded WHILE MOVING? Possible. If this is done in 25 mph winds stopped, can it take it?

If I land on a road on the dotted line (5 lanes, two on each side, one down the middle, for example, found quite often around the USA) in the RIGHT lane (we don't drive on the left side because we are not on a horse trying to kill someone with our sword...just kidding here...), how can I pull over if the wings are not folded? Most entrances to parking places are 16-20 ft wide (2 cars) and if the wing is 24-50ft, just how do you get off the road without them ALREADY shortened enough to squeeze in? Being secured for 65 mph is another thing. Land, shorten span, pull over, secure and go. All while staying warm in the vehicle, yes?

As I see it, a motion like the Terrafugia but 10 times faster would work, but with a top wing and a final motion to lay them on top of the center wing. The problem with the Terrafugia is the wing is in the side field of view. It makes it feel like you are driving a large cargo van, not a 1000 lb roadable. If they fold back like a Glastar, then the chord is limited to 4 ft and the span increases beyond 24 ft and the drive length goes to beyond 18-20 ft.

The paradigm should be to have the wings fold while in motion. This requires some good joints. Perhaps hinged, then a main spare comes in to bridge the joint. Fold down, then slide a spar into the outer wing from a center.

BTW, I have been working on this the last two days full time. Not easy...

Comments on fold while in motion? Ideas?

My configuration is: High wing with center delta (8 feet wide and 15 ft long tip to tail...like the Sea-Era, but flat) with panel wings (like the Sea-Era, but tapered). The panel wing inboard 8ft chord tapers to 4 feet outboard with added span of 8 feet. (Gives a taper ratio that is min induced drag). Total span is 24 ft, which is 1 ft less than a typical road width. Delta wing area is 88 sft and panels 96 sft, for a total of 184 sft. This allows a road landing if you can land in the middle without drift.


Holden
 
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Rienk

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The upper picture shows that the rear push tube is assembled, the front one still needs it's automatic connection. The lower picture shows the not assembled push tubes arriving from the wing (wing mounted on fuselage). The triangular receptors "catch" the triangular connections on the wing. The receptors you see in the fuselage are steered via a push tube, that connects to the half-round lug you can see just underneath it.

By putting the hinge point at the same place, any translation of the wing that's less than 1/4" has zero net effect on the position of the control surface.

Virtually zero on all questions I'd say. Mostly dependent on your concept (wing position, type of tail). For an unstrutted, one-piece high wing you might very well have a lighter structure as any other 103 ultralight. Use flaperons and you've just cut complexity in half.
It would be nice to see pictures of everything in place (no parts missing).
Does anyone have pictures or videos of the process?
I think I get it, but would appreciate seeing it, to make sure I understand it well enough to translate into my own application.

I have some other comments about this, but they are more pertninent to my other thread, so I'll post them there.
 

Rienk

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A few comments...

Both videos show a very slow process that just eliminated 95% of the customers. It has to be push button easy and on the run (< 35 mph).

The issue is that when you land and are still rolling, how to do fold the wings? Fighters do it...

Comments on fold while in motion? Ideas?
Holden, I think you are posting these comments on the wrong thread.
This is not about roadable aircraft, but normal aircraft that need a simple way to be transported - thus the "trailer and portable hangar" title.
 

Hot Wings

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Originally Posted by gtae07
Ok, I think I see how this connection works. Let me see if I get this right:
The inboard receptors normally pivot about the same axis as the triangle on the wing (i.e., the lower inboard pin on the gray wing-mounted bracket). But the actual pivot point is on the little fiberglass tab attached to the gray rod that runs underneath everything. This allows the pivot point to float with the wing's pivot point.

Compared to the mechanism used in the Daimond (1:08/1:09 is a good shot in the video post #52) is there really that much advantage to floating pivot for the fuselage side control sockets? For a plane that isn't intended to be a competition plane it seems the added manual step of inserting the pivot pin wouldn't be worth the time, and just one more thing to forget or potentially do wrong?

I presume that diss-assembly is by deflecting the fiberglass tab over the end of the ball pointed rod, rotating about the lower greenish tube and then withdrawing the whole elongated "C" assembly of pin/tube/fiberglass tab?
 
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