Droop Wing Tip internal support

[GaryK]

I modified and added Spar extensions to help stiffen the Fiberglas Droop tip on my Yukon, The aft end of the wingtip was quite floppy with just the spade box support as mentioned in my Moose manual.
1) First of all I was not furnished any Spar Extensions for the Wing Tips so bent my own up with 0.032" and drilled 5" dia. lightening holes.
2) The Spar extension at front of the Spade had a doubler provided in the kit which was longer than the spade box so I added flanges to the part that extended past the provided spar extension. This added support 4" farther out at the spade corner.
3) Last modification was bending up a short spar extension 4.5" long that would attach the the spade box rib. The aft end of the wing tip is now quite stiff and also lined up with aileron except the tip was 5/8" longer than the aileron.

Droop Tip inner structure

4) Added more fiberglass resin and mat inside of trailing edge of tip and then cut end to match line of adjacent aileron. At same time, added a strip of fiber mat along full length inside the tip seam. The seam needed to be ground on outside and the seam joint seamed quite thin.

Strip of fiberglass added at seam

Below photo does not show line of clecos/rivet holes of the last short spar extension and was taken before end of tip cut off to match aileron.

almost Finished Tip install

[mikeh]

Looks good Gary. FWIW I did a similar thing with main and rear spar extensions on our Rebel......without spades of course.
Cheers
Mike

[Nedkelly]

Hi im about to fit my elite droop tip.
How did you cut the tip..?
The manual says to set up at aileron reflex position..did you.
Did you set up on a wing ?or on a work bench.
And any pointers there.

How many stiffeners did you install top and bottom.
Did you connect them to wing stiffeners.

How did you attach the main spar extention. ?

Any other helpful photos appreciated. Manual sucks.

Anyone outthere intall led landing lite in tip,,?????what type and lumens?

Thanks in advance.
Other stuff.
I need help with tip install.
Windshield install. Trim hold down options.
Gas tank pressure test,,,possible to put access panels on temporary in case of leaks. ??

Cheers. Paul

[Nedkelly]

By the way. Great pics. Thanks for the post..

[GaryK]

Paul, Sorry for late reply, I don't have email notification setup with the forum so didn't see your questions.
I cut tip with 0.040" abrasive cutoff disc in 4.5" did angle grinder. Yes I did set up the tip with aileron in the 5 deg reflex. I put the tips on when the wing was my assembly table. I put 3 stringers inside fiberglass top and another 3 each bottom not counting the spar extensions. They stop just 1/16" short of the wing skin. The spar extensions are attached with 3/4" rt angle x 1/8 thick that riveted to wing stringers inside of wing and then extend out though the last rib like the manual explained. A key point is to have tail of wingtip restrained to match aileron reflex when drilling tip to wing. This is important to have it aligned when it is done.

I also installed LED wingtip lights I used Wheel Microburst II series ( same as Microburst III but not certified) If you want planeFAA certified for night flight you will need the Microburst III lights. Installed a 0.032" doubler inside the fiberglas with anchor nuts for the light. Made the doubler 1" wider and longer than the light footprint.


As far as Gas Tank test, I used 50 inches of water as pressure and used a scheider valve ( inner tube stem valve ) so you can add in short bursts and avoid risk of blowing up tank. I wondered same thing about temp install of the gas tank access panels but was advised that the temp install and then the final install also created risks. I went ahead and prosealled the access panels and riveted. On left tank had one leak that was from center of an access panel tank rivet ( must have failed the end seal on rivet). Easy to proseal from outside.
Right tank had a slow leak through the tank rib inside the curl of the stringer on top skin. Cut access panel outside tank in bottom and repaired from there.

[Jerry Folkerts]

I find a dremel with cutoff wheel is easiest to use on fiberglass. You get a really fine cut. I also did more cursing on wing tips than any other part of the build.

[Nedkelly]

Thanks for reply Garry. Still not done. Will eventually post pics.

[c120pilot]

Gary,
Nice fiberglass work. I am fitting droop tips on my Rebel. I sort of copied what was done on a Moose. The trailing edge was flexible on mine as well so I added a second support connected to the original one just for alignment purposes. The main spar I used .040, rear spar is .032. It replaces the >032 doubler for the flaperon bracket. I extended all the stringers with .025 to keep it from flexing so much. The tip light I added .032 with a nut plate flush riveted. We put resin with microbeads on it to hold the fiberglass tip flat for the light to sit square. There are 2 standoffs and adel clamps to support the wires with an access hole to remove them if necessary. Not done with them yet.

Curtis
N175LW

[c120pilot]

Here are a few more pictures.

Curtis

[monty777er]

Very nice. I've yet to do my tips so this is helpful. However when I recieved my droop tips from MAM I did not get any additional parts. What should I have recieved such as stringer material and ribs?
Thanks
Monty

[c120pilot]

Monty,
I am still laughing..... MAM was very fast getting my tips. But there were no instructions, suggestions or parts with it. I fabricated all my pieces.
I overlapped them under the skin but on top of the spars and stringers. I ended up putting the stringers more like a U-shape than a J- shape. If they are a J- shape it would mean taking some meat out of the ribs and I didn't want to do that. They go under 4 rivets and up close you can barely see any difference.
The rear spar was the toughest. I removed the .032 doubler under the flaperon hinge and made the spar to match the factory spar. This makes the extention overlap more than necessary but didn't have to change anything on the flaperon hinges. I just back drilled all the original doubler holes.
The only thing is on the top trailing edge it put the extention under the spar and skin making a big step for the fiberglass tip. I added an .032 strip on top with a few flush rivets to smooth out this transition. Also narrowed the top of the rear extention to 1', just didn't need the extra width there (you can see it in the picture). The extra wedge trailing edge rib is .020 with a lightening hole. I used .025 L brackets to attach the ribs just because it's stronger there. I used a scrap piece of stringer material to attach the trailing ribs together to keep them parallel to each other.
It is a PITA but looks good and you can pick up the wing from the trailing edge without flexing it.
Hope this helps, good luck.

Curtis

[monty777er]

Haha but sad faced; I guess I got the same 'kit' as you did. I'll revisit this post when I get to the tips.

[Flygirl]

Very nice. I've yet to do my tips so this is helpful. However when I recieved my droop tips from MAM I did not get any additional parts. What should I have recieved such as stringer material and ribs?
Thanks
Monty

To those ordering Droop Tips. The attachment is a ship list of parts that should be coming with your tips.

[c120pilot]

Something changed. My daughter in Washington drove to the factory and picked them up for me. Just the tips no drawings or instructions. I just winged it.........

Curtis

[GaryK]

Curtis,
Nice job on the wingtips and great photos to show the stringer extensions.