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Variations on attaching the wing tips...

rsr3

Well Known Member
I've got to that stage of the build where I'm giving thought to attaching the wing tips. I've seen different methods of attaching them, such as:

- pulled rivets
- screws
- hinges

I think I'm unlikely to remove them once they're on - even with annual inspections I can't see that there will be a great deal to be gained from taking them off, when a borescope could do the same thing?

If anybody would be good enough to explain their reasoning for their chosen method of attaching the wing tips that would be very useful.

Thanks in advance!

Rob
 
Most builders have nav/strobes mounted on the tips, some included landing lights (like me). Add a VOR antenna to one wing and there is ample reason to be able to remove the tips for future maintenance.

I use nutplates and tinnerman washers under the screw heads as this protect the wing paint. I don?t use hinge pins as I enclose the trailing edge tip rib (like all the other control surface end ribs).

Carl
 
I think I'm unlikely to remove them once they're on - even with annual inspections I can't see that there will be a great deal to be gained from taking them off, when a borescope could do the same thing?


Rob

Rob, I think this thought will bite you.
 
#6 countersunk screws and nutplates

I went with #6 countersunk Torx stainless steel screws and floating nutplates. I like the way it turned out. I guess you would be surprised how many times you might need to remove them.

You can kind of see how it was done here:

http://www.rv8.ch/inside-the-wingtips/

img_8789-1024x768.jpg
 
I went the hinge rout. Reason? I have two sets of wing tips. One set is all painted, the other is not.
The not painted set I modeled smoke cartridge attach brackets and ignition system for a formation flight team I used to work with. I also fabricated a wing tip "locker" in one of this set.
I can remove and replace a wing tip in about five minutes and the not scratch up any paint.
The only drawback was that I also needed two sets of wing tip mounted nav position and strobe lights as well as the fiberglass blisters to mount them.
 
I used #4 ss screws. Makes for a nice finish with screw heads looking similar size and spacing to rivets in the rest of the wing. I only have removed tip 2–3 times in 14 years of flying. Just a check every 2-3 condition inspection to take a peek inside.
I would not do it again as the #4s are easy to strip the head with a battery screwdriver (I have specific bit I use only for these #4s), easy to twist off heads, and too many screws to remove to take off tip.
 
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#6 SS screws and regular plate nuts for me and I do remove them every condition inspection.
 
I built my RV simple. Used pulled rivets per plans. I have position lights only in my wingtips and bulbs/connectors are easily inspectable. However, through 9 years of flying I had to remove the tips twice. Once I hit a hard snow bank while taxiing and second time buchered both leading edges on rollout. I would install screws or combination screws/hinges if I do it again. It would make repairs easier :)
 
I went with #6 countersunk Torx stainless steel screws and floating nutplates.

I just found out about the floating nutplates. Sometimes the handmade holes don't quite aligned and the floating nutplates saved the day.
 
Ok everyone, thanks for that. So, fit them such that they can be removed as required, fair enough. Sounds sensible.

Using screws and tinnerman washers sounds like the easiest way, but I do like the idea of minimal visibility that the hinge method offers. If I went down the hinge route, how do you stop the hinge from pulling the rivets through the fibreglass on the wingtip half of the hinge? That must be quite difficult to reinforce, unlike the screw method by which a strip of aluminium can be riveted inbetween the nutplates and the fibreglass of the wingtip.

Thanks!
 
An adhesive under the aluminum strip or hinge would reinforce it well. Also, instead of tinnermans, consider thin SS flat washers, pressed in the appropriate dimple die. Smaller, clean and effective.
 
floating nutplates

I just found out about the floating nutplates. Sometimes the handmade holes don't quite aligned and the floating nutplates saved the day.
Indeed, they are really nice. I bought a big bag full at Oshkosh from one of the tent dealers there - it was no where near as expensive as the normal price.

The nice thing is that the screws line up perfectly with the dimpled hole, no sideways stresses.

The torx screws make it fast and easy to install and remove with an electric screwdriver without worrying about stripping the head.

Be careful riveting the floating nutplate on - if you are not lined up right with the rivet you can pinch the nutplate and it won't move freely.
 
I built my RV simple. Used pulled rivets per plans. I have position lights only in my wingtips and bulbs/connectors are easily inspectable. However, through 9 years of flying I had to remove the tips twice. Once I hit a hard snow bank while taxiing and second time buchered both leading edges on rollout. I would install screws or combination screws/hinges if I do it again. It would make repairs easier :)

Always learning from others....snow bank..check, do not hit. Got it.
Rollout...do not butcher leading edges....?? :confused: Overrun into corn field maybe?? Flock of boids....??
R
 
An adhesive under the aluminum strip or hinge would reinforce it well. Also, instead of tinnermans, consider thin SS flat washers, pressed in the appropriate dimple die. Smaller, clean and effective.

I prep both surfaces and then Fay Seal all my hinges and backing aluminum for fiberglass parts with Pro-Seal, then rivet after they Pro-Seal is set.
 
If it?s a taildragger consider making it removable. Ground loops are hard on wingtips.......
 
Probably depends on what you put in the wing tips. I have my APRS antenna and unit in there. I had to replace the antenna a few years ago when it stopped sending out packets. Found a loose wire. I know others with Archer COM/NAV antennas in the wing tips. Most likely you will want to inspect in there at some point down the road, or add/change something.
 
I've got to that stage of the build where I'm giving thought to attaching the wing tips. I've seen different methods of attaching them, such as:

- pulled rivets
- screws
- hinges

I think I'm unlikely to remove them once they're on - even with annual inspections I can't see that there will be a great deal to be gained from taking them off, when a borescope could do the same thing?

If anybody would be good enough to explain their reasoning for their chosen method of attaching the wing tips that would be very useful.

Thanks in advance!

Rob

- hinge would be my vote. Easy, no paint damage removal. Never say never. You will end up back in there for some reason.
 
Ok - hinge set up it is, then. That was my initial thought but as time went by I thought that just blind riveting them on would be quick and easy.. i.e. Lazy!

Final thought - I think - would you recommend using AD4 rivets to put the hinge on so that the rivet head is a bit bigger and more reluctant to pull through the fibreglass?

Thanks for taking the time to reply everyone, it is really appreciated.

Rob
 
The torx screws make it fast and easy to install and remove with an electric screwdriver without worrying about stripping the head.

+1 on the torx screws. I wish I know about them before working on the fuselage.
 
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