Wing Springs

[perryv1]

I have a pair on my BC12d-1 and I was wondering if anyone knows of any others still flying. About 10 years ago, a guy in NY put an ad in trade a plane saying his was the only one. I called him right up and Oh No your not, and he confessed that he had heard of another in NJ. just curious.

[NC36061]

Re: Wing Springs

OK, I'll ask......what are you referring to?

Dave

[Vasey fan]

Re: Wing Springs

The Wings with Springs STC?

I've always wondered what that setup looked liked. Suppose you could post some pics?

[jack clifton]

Re: Wing Springs

What do they do? Curious to see and hear also.

[perryv1]

Re: Wing Springs

Ill get some pics tomorrow. Friday 11/23 and ill see if I can figure out how to post them tomorrow night
PV

[Ragwing nut]

Re: Wing Springs

What do they do? Curious to see and hear also.

They attach to the struts I think and are suppose to soften the ride. Not a new concept, but one that never caught on. I think it was also tried back in the 20's.

Mike

[perryv1]

Re: Wing Springs








Heres some pics of the wing springs
There is a pressure tank located at the front of the seat with a section for each side (sealed from each other)and I usually keep about 200psi in them.
I like to fill them with nitrogen because for the temperature changes but it is hard to come by for me,so i generally just fill them with air.These allow about 36" possible travel at the wing tips,and even in smoth air you can look at the struts and wach them move. Its really kool.
Every annual I replace the wing attach bolts but I have Never seen ANY wear on the bolts or the fittings, you can see where they piviot on the bolts but never any play in the joint.
I dont know if the extra dihedral makes any differance in the performance of the plane but stall carateristics and landing flair are the same as any other t-craft Ive floan.

[Ragwing nut]

Re: Wing Springs

The extra dihedral will stabilize it laterally, but it will also slow it down. I took the dihedral out of a Tripacer one time to try it, gained 5-10 mph indicated and was a handful in the air.

Mike

[perryv1]

Re: Wing Springs

I can cruse on floats about 95 and on wheels about 105 indicated.I think my airspeed indicator is pretty accurate even a about 60 years old
I use a seaplane prop 74-42 year around because i put the plane on skis too.I usually run it about 2400 rpm to get the speeds im reffering to. Is that tyipical? (sp)
Thanks for your interest.
PV

[Forrest Barber]

Re: Wing Springs

Thank you very much for the excellent photos of the "Wings with Springs". I recall seeing them for the first time here in Alliance as the ship rounded base to final real tight & I thought , SHxx the wings are breaking off!!
, I got engaged by the apparent owner of the STC at OSH one time at a Forumn, had never met him; Boy was he adamant about the virtues of the system. Yes I have flown them kind of neat!
I really see no improvement, but do not knock them. Would like to see you bring that ship to the Fly-In this year July 6th, 7th & 8th , 2007.
I always put them in the category of a retractable landing gear on a Bensen Gyrocopter, or rudder pedals on a Ercoupe.
Anybody else ha them installed?

[VictorBravo]

Re: Wing Springs

I'm intrugued by these things but I have a question...

If the wings move up and down in a flapping motion with those spring units, how does the control cable geometry not get screwed up? There are primary control cables running through the rear of the cabin, supported by steel "fairlead" tubes welded to the longerons. If the wingtips go up 36 inches, those cables will try to stretch up through the fairlead tubes, not to mention tightening up the cables going to the control yoke. It would APPEAR that the whle aileron cabale system would go into high tension and bind up due to a change in geometry.

I have a lot of time in airplanes with long springy flexible wings, so I can vouch for the comfort level you would get... but it does seem like the cable rigging would be all fouled up, not to mention how the HELL would the wing root cover strips stay in place?

[DanBrown]

Re: Wing Springs

Yes -- very interesting. Bill, IMHO I don't see why a small wing angle change without affecting the distance from the fusalage attach points to the control surface would put any significant tension on the control cables.

[Vasey fan]

Re: Wing Springs

Perry, thanks for the photos. IIRC, they were available for Pipers & C-120/140's also, haven't ever crossed paths with one so equipped though.

[alwaysoar]

Re: Wing Springs

It looks like both struts attach only at one point on the bolt where it passes through the most forward and middle ear on the fuselage fitting. Even though the bolt goes through all three ears, doesn't that put most of the stress on the forward and middle ears? Isn't that going to increase stress on those ears and increase the potential for cracks?

Also, Perry, what do you have for an engine? If it's a 65, you're running over red line. Must be a 75 or 85 and I can't think offhand of what those redlines or normal cruise settings are.

Ed@BTV VT
TF 527

[VictorBravo]

Re: Wing Springs

Yes -- very interesting. Bill, IMHO I don't see why a small wing angle change without affecting the distance from the fusalage attach points to the control surface would put any significant tension on the control cables.

It's primarily because there are short tubes welded on the longerons that the cables go through.

If the bellcranks out in the wings are both raised by a foot relative to the fuselage, a straight line drawn between those bellcranks (the straight line formed by the cables) is also raised by a foot.

So the center point of the aileron cables (which is the two steel bars with the turnbuckles attached to them) tries to raise up a foot so it still forms a straight line between the aileron bellcranks in the wings.

But the little tubes welded on the longerons do NOT raise up a foot because they are welded onto the fuselage and the wings are moving relative to the fuselage. So the cables now have a longer path to go because they can no longer be in a straight line between the bellcranks.

Add to this the fact that as both wingtips go upward hinging on the attach bolts, the distance between the aileron bellcranks also gets a fraction shorter, so you might lose a little tension on the cable. This may or may not compensate for the increase in tension caused by the cable route becoming longer, but it changes the shape of the cable routing nonetheless.

Add to this the fact that the cables will now be sawing against the edges of tose short tubes if the pilot moves the control yoke.

Add to this the fact that the axis of the cables is now at a slight angle to the grooves in the pulleys.

Add to this the fact that if you just removed the tubes and ALLOWED the center attach point of the cables to rise upward in the cabin when the wings flex upwards... the cable center turnbuckle assembly would be trying to pull tension on the lower cable loop that connects to the control yokes, sprockets, lower pulleys, etc.

All of these movements are fairly small, admittedly. But throwing everything just a little off-kilter in an airplane is still a problem where primary cables are concerned. I believe it IS completely possible to redesign or modify the system to allow this kind of movement, but it ain't no little weekend project.

IF the T-craft had been designed with push-pull tubes and spherical bearings on all of them, then it would probably be a lot easier. The spherical rod end bearings would gladly take up a few degrees of off-axis motion without a problem.