flap return spring - I'm stumped

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KevinC
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flap return spring - I'm stumped

Post by KevinC »

Ok, for the first time on the wings I've hit a problem.  Last night I worked on the flap return spring install.  As usual, the manual is poor.  My problem:  with the same amount of cutout of the leading edge of the flap (actually a little more) the spring binds on the fiberglass at maximum flap deployment.  The cut out slot for the spring is already cut to 1.25" from the bottom rear edge of the flap leading edge fiberglass.  So - do I keep cutting until it doesn't touch the spring when the flap is fully deployed?  The geometry seems messed up.

thanks

k
DaveU
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Post by DaveU »

Kevin,

I agree.  When the flaps are fully deployed, the spring does hit the bottom of the cutout.  I don't think this hurts anything.  It just touches due to the angle on the spring.

I had to shorten the spring, nearly an inch shorter, and bend a new hook on it.  This is the only way it would hold the flaps up when sitting on the ground.  THe drooping flaps will strike the fuselage when folding the wing if not really careful.

DAve
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KevinC
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ok - next on the flap return spring

Post by KevinC »

Thanks, Dave for the explanation.  It is all installed & riveted.

So - the other night after work I was imagining that everything was covered & painted.  Time for re-assembly.  How in the hell do you get the spring back on the tab inside that little tiny hole in the flap leading edge?  I tried every tool in my shop to hold on to it - while up against the wing, in position.  I assume the spring stays with the wing?  Yikes!

Way out ahead of myself, but ?

k
scubarider
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silly but.......

Post by scubarider »

Might sound bass assackwards but....I am building the whole plane from the inside out.  Then when everything is fully covered and ready for paint will spend the time to tape tape tape....and paint the plane "whole".  This will save the time of assembly disassembly etc.  Any problems with this plan?
Dennis
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DaveU
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Post by DaveU »

I was able to use a pair of long curved nose needle nose pliers.  I hooked the spring in the flap before attaching the flap to the wing.  I then was able to use the same pliers and hook the spring onto the tab on the wing.  I did have to modify the spring by shortening it and rebending a hook.  I had to modify the hook a little to get it on the tab in the flap.  I cut nearly an inch off the spring to give it enough tension to hold the flap up on the ground.

I did poke a screwdriver through the fabric trying to get the spring off to shorten it.  Ouch, good thing I have some white duct tape to cover the hole.

Dave
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stede52
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flap spring setup

Post by stede52 »

Hey guys,
I'm trying a new flap spring setup on my highlander which will work 100 times better then the original setup.  I got the idea from another aircraft builder so I'm not taking credit for this one but I thought I'd pass it on to the new builders.  The setup eliminates the annoying issue of the sagging flap :shock: , The setup allows you to tension the new double length spring so the flap stay in place. The problem with the spring that comes with the kit is that it can easily be overstretch if wind hits your flaps from the backside which can overstretch the spring resulting in sagging flaps :(  Basically the setup positions a new longer spring parallel to the wing spar. The 1/16" cable is pulled thru the root rib and nico pressed to the outside of the rib at the desired tension. By the way I'm sure this can be made other ways but this worked for me:
My hardware consisted of:
new pulley standoff ( made mine with a 2.5 standoff to clear the flap pulley
1-1.5 pulley
1/16" steel cable
oval nico press sleeve (double hole)
nico stop sleeve (single hole)
new spring, same diameter but double the length (available at hardware stores)
1/16" thimbles
modified W-0510 Spar attach bracket to a hook configuration




Steve
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stede52
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flap spring setup

Post by stede52 »

More pics of the setup

Steve
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rmullins
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Post by rmullins »

We didn't much like the original spring either so we went to our Ace Hardware and bought a heavier spring. It works great but it was a real SOB to re-attach after everything was covered (we also ended up with a patched hole). I would expect your method would be much easier to reconnect after covering.
Rick Mullins  #144
Cincinnati, Oh
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scubarider2
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Post by scubarider2 »

Yep, did the same.  I went to the local hardware store and bought a stronger, shorter spring.  Then with the help of a friend and some long nose needle pliers we went and put the wing side on first.  Then stretched it out and put it on the flap.  Was a  :twisted:   but no problem at all with sagging flaps....
Dennis
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Johnny C!
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Post by Johnny C! »

Dennis,
 The spring you bought has a similar
wire diameter, but the spring's over-
all length is shorter than the one
supplied with the kit?

John
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scubarider2
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Post by scubarider2 »

It was both shorter and tighter.  I bought several so just in case one did not fit go to the next size.  I got the tightest I could get put on.  Absolutely no flap sag.  
Dennis
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SheepdogRD
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Re: flap spring setup

Post by SheepdogRD »

stede52 wrote:Hey guys,
I'm trying a new flap spring setup on my highlander which will work 100 times better then the original setup.  I got the idea from another aircraft builder so I'm not taking credit for this one but I thought I'd pass it on to the new builders.  The setup eliminates the annoying issue of the sagging flap :shock: , The setup allows you to tension the new double length spring so the flap stay in place. The problem with the spring that comes with the kit is that it can easily be overstretch if wind hits your flaps from the backside which can overstretch the spring resulting in sagging flaps :(  Basically the setup positions a new longer spring parallel to the wing spar. The 1/16" cable is pulled thru the root rib and nico pressed to the outside of the rib at the desired tension. By the way I'm sure this can be made other ways but this worked for me:
My hardware consisted of:
new pulley standoff ( made mine with a 2.5 standoff to clear the flap pulley
1-1.5 pulley
1/16" steel cable
oval nico press sleeve (double hole)
nico stop sleeve (single hole)
new spring, same diameter but double the length (available at hardware stores)
1/16" thimbles
modified W-0510 Spar attach bracket to a hook configuration

Steve
Steve, I'm ready to mount the flap springs, and I read about this change you made in your flap spring system. I'm wondering how this worked for you. Would you use this again, or would you go back to the method in the manual?

Thanks . . .
Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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stede52
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Re: flap return spring - I'm stumped

Post by stede52 »

Sheepdog,
Yes I would do it again, it just takes more time to put it together. The shorter spring works well as long a you don't have a gust of wind from the rear that blows down the flaps and over-stretches the springs and then the flap droops. That happened on my first Highlander. The spring in this system can never be over-stretched because of the length of spring but it can also be tighten so the flap won't droop over time or in wind gusts.
Steve D N419LD
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stede52
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Re: flap return spring - I'm stumped

Post by stede52 »

Sheepdog
I was just reminded that the pictures don't show how the spring is tighten. If you look at the first picture you'll see a cable attached to the inboard end of the spring. That cable extends through the butt rib of the wing and once the flaps are hooked up that cable is pulled as tight as needed to hold up the flaps and then secured by a single wire nicopress sleeve.
Steve D N419LD
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SheepdogRD
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Re: flap return spring - I'm stumped

Post by SheepdogRD »

The more I look at that flap return system, the better I like it. It adds some cost and a few ounces of weight, but it's good insurance against wind damage, and it'll make for easier maintenance. I also like the much smaller holes in the trailing edges.

I'm considering mounting the return spring on the outboard side of the bellcrank rib, so the flap return parts will be in the third bay. That will keep things less cluttered in the second bay, and it looks like it will let me use the MS20219-4 pulley and 3/32" cable used on the rest of the plane. I'll need to add inspection access on the bottom of that third bay, too.

I'm thinking of fastening the W-0690.0 attach bracket to rib #3, attaching the spring to that, and making a single cable that runs from the other end of the spring, around the pulley, and out to the W-0695.0 spar attach bracket. That wouldn't leave a way to adjust the cable, though, so I may consider adding a simple adjuster between spring and cable, something similar to these:
Cable adjuster.jpg
Yours is certainly the lighter, less expensive approach; the only advantage to this is adjustability without a Nicopress tool.

Our pulley standoff will be 2.25" from the bottom of the base to the center of the pulley. That will let us keep the cable in pretty close to the rib -- about an inch away -- but still leave some working room.

I'll order the pulleys and necessary fasteners, make the standoffs, and go spring hunting.

This seems pretty straightforward. It's the first change I've considered where it doesn't look like it will add a week or two to the build process. :D

Thanks for putting this on the forum, Steve.
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Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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