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Wing Tip Mounting

11 posts in this topic

Posted

Wing tips (droop style Model III).  Do these but up to the outboard wing rib surface (via maybe a attach plate, wing screws go into this plate) or do these actually go over the rib (I.e. wingtip screws go right into the outboard rib)?

 

The instruction seem to indicate the wingtips actually encapsulate the rib.  Just want to make sure. 

 

Anyone have a few pics they could post?

 

Many thanks,

 

Larry S.

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Posted

I have seen some people spend a lot of time making the tips fit flush with the end rib.  Most just follow the book and screw the tips on right over the top of the rib.  I have seen a few with nut plates rivet to the rib and machine screws used.  Wood screws (or sheet metal screws) into the rib is the fastest way to do it.  drill the holes, run the screws in, take the screws out and wick some thin CA down the holes to harden the wood threads and your good to go for the fast approach to putting them on.

 

:BC:

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Posted (edited)

Leni,

What is CA?

IMO, if you are going to have tip lights, it is better to make the tips removable - I like aluminum angles and rivnuts - If no lights, then just put them on and forget removing them. If you ever need to hang your wing, or put new fabric on, the removable tips make it easier.

One of my Kitfox manuals says to put dope and surface tape on the edge of them to make them permanent.

EDMO

Edited by Ed In Missouri

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Posted

Ed,

 

CA is the common name for .... cyanoacrylate or super glue :lol:  Thin super glue wicked into the wood holes makes a pretty good thread that does not pull out easily, especially if your going to be taking the screws in and out.  Old model airplane builders trick.

 

:BC:

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Posted (edited)

Ed,

 

CA is the common name for .... cyanoacrylate or super glue :lol:  Thin super glue wicked into the wood holes makes a pretty good thread that does not pull out easily, especially if your going to be taking the screws in and out.  Old model airplane builders trick.

 

:BC:

next question - HOW do you thin Superglue? I didn't have an instructor when I was building models - Just "Winged" it!

EDMO

Edited by Ed In Missouri

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Posted

HOW do you thin Superglue?

 

Hi Ed. You by it that way. Go to a hobby shop, and ask for thin CA. They'll know what you need.

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Posted

Larry -

 

Both of my KF's had/have droop tips fastened directly on top of the tip rib capstrip, although each a little differently. In both cases the edge of the wing tip material was fit flush to the inboard edge of the capstrip. However, the model 3 had sheet metal screws into the outboard half of the capstrip only and the model 4 has pan head sheet metal screws into a metal backer strip epoxied under the inboard half of the tip rib capstrip. Tips on both did not sit not perfectly flat along the capstrip and the model 3 tips had some stress cracking of the paint under the smaller screw heads, probably due to overly aggressive tightening more than anything. I did use Leni's CA trick on the model 3 and it made a big difference when screwing directly into the wood capstrip without any backer, highly recommended.There is no need to 'thin' CA, it's already thin enough.

 

If you take the time to install nutplates and machine screws, couple ways you can do that too. Either with the tip directly on top of the capstrip like in the attached photo or flush with the top of the wing using attachment strips as in the current KF removable tip mounting kit (see attached .pdf). Aesthetically, I like the tip surface flush with the wing surface those I've seen seem using attachment strips and machine screw nutplates sit nice and flat with no 'waves'.

 

Maybe some ideas for you in this old thread too if you missed it: http://www.avidfoxflyers.com/index.php?/topic/548-wing-tips/

wingtip install.pdf

post-53-0-85195900-1427055303.jpg

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Posted

At hobby shops or online you can order several viscosities of superglue.  Gel, Super thick, thick, medium, thin super thin, foam safe, odorless etc.  They each have their place and I have a few bottles of most of them in the shop.   When I had my online hobby shop I ordered direct and had my labels put on them.  If your gluing ply to ply, use a thick CA, if your making thread bosses, use thin to really wick in there and seal up the wood, infact, apply it a few times to really get the wood loaded.  Every other year of so I soak my rib tails down with the thin super glue to keep them water proof and in good shape.  If wood starts to get punky, you can most times save it pretty quickly with thin CA.

 

:BC:

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Posted

Actually, in my Ancient Times, when we needed glue for our models of DaVinchi's plane, we had to make it out of snail or slug spit, or boil certain weeds while we smoked the flowers! :lol:

EDMO

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Posted

All great feedback.  DHolly thanks for the pics!

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Posted (edited)

All great feedback.  DHolly thanks for the pics!

If you read the old posts, you may have seen that I favor the aluminum angles riveted to the rib instead of the capstrip, and I like Rivnuts instead of the nutplates that are shown in Doug's photos.

I am also thinking about adding a rubber edge to the tips to seal them and protect the fabric from chaffing.

EDMO

Edited by Ed In Missouri

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