flap return spring - I'm stumped

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stede52
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Re: flap return spring - I'm stumped

Post by stede52 »

you also want to use a spring that is about twice the length of the spring in the kit and as strong or a little stronger. The longer spring eliminate the problem of over stretching. I'm not sure if you'll have room for the long spring and that bracket setup becasue you will be stretching the spring very close to or thru the false rib to get enough tension to hold up the flap, you will need more tension then you think.
Steve D N419LD
xpflyr
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Re: flap spring setup

Post by xpflyr »

SheepdogRD wrote:
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 . . .
Another option is in this thread.
www.wingsforum.com/viewtopic.php?f=218&t=18900
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SheepdogRD
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Re: flap spring setup

Post by SheepdogRD »

stede52 wrote:you also want to use a spring that is about twice the length of the spring in the kit and as strong or a little stronger. The longer spring eliminate the problem of over stretching. I'm not sure if you'll have room for the long spring and that bracket setup becasue you will be stretching the spring very close to or thru the false rib to get enough tension to hold up the flap, you will need more tension then you think.
That helps on spring selection.

If I don't use the adjuster system that worked for you, I suspect I could run the hole-plate type adjuster into an additional bay and all it would add would be a little extra cable; or perhaps I could make a shorter hole-plate adjuster. Once installed, it looks like this will rarely need adjustment. Is that your experience?
xpflyr wrote:Another option is in this thread.
www.wingsforum.com/viewtopic.php?f=218&t=18900
It wouldn't help resolve the spring stretching problem, but that's interesting -- attaching the standard flap spring in the open area at the wing root, rather than through the trailing edge. That probably makes it easier to install and service.
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 »

SheepdogRD wrote:If I don't use the adjuster system that worked for you, I suspect I could run the hole-plate type adjuster into an additional bay and all it would add would be a little extra cable; or perhaps I could make a shorter hole-plate adjuster. Once installed, it looks like this will rarely need adjustment. Is that your experience?
Rather then using a cable and nico sleeve for adjustment at the butt ribb, find or make a long eye bolt you can attach to the spring and extend thru the butt rib. Use a nut and washer on it to tension the spring. Yes, you won't need to adjust it unless it was too loose to begin with.
Steve D N419LD
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danerazz
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Re: flap return spring - I'm stumped

Post by danerazz »

For a flap root to fuselage return spring you could rig something up other than as in the picture. I'll have to look at it when I get home, but I think a simpler idea is to use the stock setup and add a limit cable or something similar to prevent the flap from being overextended by gusts of wind.
Dane

Paralysis by analysis
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SheepdogRD
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Re: flap return spring - I'm stumped

Post by SheepdogRD »

stede52 wrote:Rather then using a cable and nico sleeve for adjustment at the butt ribb, find or make a long eye bolt you can attach to the spring and extend thru the butt rib. Use a nut and washer on it to tension the spring. Yes, you won't need to adjust it unless it was too loose to begin with.
That makes it even easier to install. Thanks, Steve.
danerazz wrote:For a flap root to fuselage return spring you could rig something up other than as in the picture. I'll have to look at it when I get home, but I think a simpler idea is to use the stock setup and add a limit cable or something similar to prevent the flap from being overextended by gusts of wind.
Agreed, that could be simpler, or at least closer to the manual. But this alternate system eliminates those big holes in the trailing edge, and it seems a lot less jammed into a small spot. I'm going to give it a shot.
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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SheepdogRD
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Re: flap return spring - I'm stumped

Post by SheepdogRD »

After going over this a couple of times, I realized that I was looking at a different layout, Steve. I had planned to build the system so the spring is attached running outboard from the hinged rib. You're talking about mounting it so it runs inboard, behind the tank. It finally occurred to me that placing it behind the tank means I can attach the cable as you suggest -- through the butt rib. That means I can adjust it by folding the wing. That's a nice touch.

If I slot the threaded end of the eyebolt, I can adjust the tension with an open-end wrench and a screwdriver. A double nut will keep it from loosening.
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 »

You got it!! :D, actually if I did it again I'd do the threated rod/eye bolt because it would be easier to adjust then a nico sleeve, wish I would have thought of that earlier :?
Steve D N419LD
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gkremers
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Re: flap return spring - I'm stumped

Post by gkremers »

Steve,
I used your idea with some slight modifications. I did use a threaded rod, it runs through the root rib and should make adjustment easy. The pulley is mounted on a clevis that fits perfectly, I did need to press bushings in to fit the 1/4" pulley bolt. The clevis is on a 3/8" threaded rod and mounted through the hinge plate. McMaster Carr had the clevis and longer spring.

Thanks for the idea,
Gary
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stede52
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Re: flap return spring - I'm stumped

Post by stede52 »

Very nice install !!, the only potential issue I see is that the false rib may limit the mount of tension you can get unless you make the hole large enough to be able to pull the spring thru the rib. Once the flap is covered and painted it gets quite heavy and with a longer spring you need to stretch it much further than you may think to keep the flap up tight. I would increase the hole thru the rib so the spring can be pulled as far as required to get the tension you need. Better to be safe than sorry.
Steve D N419LD
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gkremers
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Re: flap return spring - I'm stumped

Post by gkremers »

I found springs with the same wire thickness and diameter. The original spring is 4", currently have it set up with a 6" spring and also found an 8" spring but it just seemed too long. The thimble is currently about 1.5" from the pulley when the flap is extended to 40+ degrees, I could make up a new cable .75" shorter.

To be safe I'll take your advice and enlarge the hole In the false rib.

Getting close to covering, just need to fabricate the pitot bracket and seal the ribs. Jason from Stewart and I discussed the nessesary wet goods needed to get the plane covered, taped and sealed.
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stede52
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Re: flap return spring - I'm stumped

Post by stede52 »

Gary,
Don't think you need to make the cable shorter, allowing the spring to be able to slip thru the rib will give you all the tension you'll need. You really did a nice job.
Steve D N419LD
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SheepdogRD
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Re: flap return spring - I'm stumped

Post by SheepdogRD »

gkremers wrote:The pulley is mounted on a clevis that fits perfectly, I did need to press bushings in to fit the 1/4" pulley bolt. The clevis is on a 3/8" threaded rod and mounted through the hinge plate. McMaster Carr had the clevis and longer spring.
That looks good, Gary. Can you provide McMaster part numbers for the clevises and springs? And can you show a picture of how you set up your wing root end of this, please?
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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gkremers
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Re: flap return spring - I'm stumped

Post by gkremers »

I'll get a picture tomorrow.

McMaster -Carr
2 Clevis 1583K14
2 Bushing 6391K131
2 Threaded Rod 90032A011

Aircraft Spruce
2 Pulley's MS20219-2
2 Terminal Assembly AN665-21R
24" SS 1/16" cable
4 Thimbles AN100C3
4 Sleeves MS51844-22

I had some 3/8 - 24 threaded rod
You'll need some jam nuts or lock nuts for the 3/8 threaded rod

Gary
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SheepdogRD
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Re: flap return spring - I'm stumped

Post by SheepdogRD »

Thanks, Gary. That's a tremendous help.
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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