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N844RS repair

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Posted

Hi all,

I have ordered the WIB gear, tail ribs, and trailing edge alum. from Airdale. I have damage to the rt. side carry trough tubes front and rear. They broke off taking the butt rib with them . The rear tube is bent Here are my plans for repairs. I have obtained a Kitfox III cabin from the front door posts, and rear at the side windows up. I have taken all measurements and they all match the Avid MK IV. I am going have it welded onto the Avid where it matches the original cabin top. All thoughts and advice appreciated.

Russ, N844RS

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Posted

All thoughts and advice appreciated.

Avifox sounds a hecka lot better than Kitvid. :hammerhead:

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Posted

Hi all,

I have ordered the WIB gear, tail ribs, and trailing edge alum. from Airdale. I have damage to the rt. side carry trough tubes front and rear. They broke off taking the butt rib with them . The rear tube is bent Here are my plans for repairs. I have obtained a Kitfox III cabin from the front door posts, and rear at the side windows up. I have taken all measurements and they all match the Avid MK IV. I am going have it welded onto the Avid where it matches the original cabin top. All thoughts and advice appreciated.

Russ, N844RS

Still looking for advice and thoughts on proposed repairs.

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Posted

Lol, no replies!? Since when has this site not even offer up an opinion or two? They must think you are craazy. C'mon, let's help the brutha out!

OK, this does sound drastic. Having owned both types, I recall the tube braces in both the headrack and the butt rib areas are different. Now that may or may not be a showstopper. IIRC, the spar pin bushings on both models are 27-1/2" center to center from front to rear spars on each side. However, the side to side length of the carry thru tubes ie. cabin width and the location of the pin bushings along the carry thru tubes must be exactly the same as well for your Avid wings to simply bolt back on after repair and function correctly. And safely. I think we can all agree on that as a start, eh?

So you say you've measured... are each of those critical measures identical on both planes? If yes, then I agree you MAY have a shot at replacing the entire top of the Avid cabin with the KF-III cabin. BUT... obviously now the location of each primary down tubes (ie. the 4 corner posts) will come into play. It would seem a lot to ask for that they too were in identical positions between both models, but pretty damn convenient if that were true. But even if they are placed perfectly, are the tubing o.d. and i.d. the same? I'm guessing the Mk-IV used bigger or thicker wall tubing... Lotsa variables.

I dunno, if it all measures out and is easier to keep the plane straight by replacing the entire head rack, I do see the value in your approach and say why not. Once tubing gets bent and is reformed it loses strength. I most certainly do NOT like the idea of a butt weld, or even a slip tube rosette welded inside, to repair a bent or broken off carry thru tube. Seems replacing the entire headrack with intact carry thru tubes would provide the best strength in that critical area. If approached very carefully and systematically with laser jig for accuracy and proper welding technique, no reason it couldn't work if the parts actually line up. And of course we'll be here to encourage you or B-slap you if you f'n it up! But it's yer plane and my .02 ain't a whole lot when talking about an aeronautical engineering salary!

Oh, and Russ, I would add one last comment... cut once, measure about 100x and do this sober. :)

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Posted

Lol, no replies!? Since when has this site not even offer up an opinion or two? They must think you are craazy. C'mon, let's help the brutha out!

Oh, and Russ, I would add one last comment... cut once, measure about 100x and do this sober. smile.gif

Well I was going to agree with you up to this point! Just how the hell is a guy spose to get good at fitting new tubes if he only has to cut and grind once for a perfect fit??? This is best done with atleast 3 other budddies standing around mixing your drinks and handing them to you. Then when youy do eph up, you will have witnesses who can pull your chain for weeks to come. This keeps the rebuild process interesting and light hearted. Your already pissed and in a bad mood cause you twisted this lil bugger up, so you really do need some humor to keep you going at this point!

OK, So Doug has some other pretty damn good points ( is it just me or does he seem to put alot of thought into his work :dunno: ) The top cage replacement is a good way to go IF all things line up as he pointed out. Can you take some pics of the damaged area and post them up? This would really help out as far as repair recomendations from the peanut gallery!!

I have seen alot of cubs up here that were twisted up pretty damn good, and we just cut out the offending tube and spliced in new ones. Yes on wing mounts just like yours. AC blah blah blah ( I am on the work computer right now and dont have it in front of me) shows how to make the required splices. Please keep in mind, that as an experimental, you dont have to comply with the AC, HOWEVER, it is a pretty DAMN GOOD idea to use tried and true methods that have been proven over a whole shit load of years and signed off by guys alot smarter than me!

If we can be of further hinderance, please dont hesitate to ask! :lol:

Oh, one last thought.. Any chance that Brett will fab you the bird cage in the event that the KF one does not fit?? I would think he could put that in the jig pretty damn easy and have one out the door in pretty short order.

:BC:

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Posted

Another thought, if it is just the rear tube, I would not think twice about just cutting that tube and splicing in a new one. If the tube is not kinked, I would just straighten it and perhaps put on a gusset or sleeve it with a split sleeve.

Take a look at Jack AK and Randys fat bastard build pics. They had to bend the carry through tubes to match their existing wings. Coversations with Aridale at the time determined this was the best fix for them. They may be ugly, but so far the wings have not folded :lol: There is not that much compression on that joint, the struts are carry most of that load.

:BC:

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Posted

Lol, no replies!? Since when has this site not even offer up an opinion or two? They must think you are craazy. C'mon, let's help the brutha out!

OK, this does sound drastic. Having owned both types, I recall the tube braces in both the headrack and the butt rib areas are different. Now that may or may not be a showstopper. IIRC, the spar pin bushings on both models are 27-1/2" center to center from front to rear spars on each side. However, the side to side length of the carry thru tubes ie. cabin width and the location of the pin bushings along the carry thru tubes must be exactly the same as well for your Avid wings to simply bolt back on after repair and function correctly. And safely. I think we can all agree on that as a start, eh?

So you say you've measured... are each of those critical measures identical on both planes? If yes, then I agree you MAY have a shot at replacing the entire top of the Avid cabin with the KF-III cabin. BUT... obviously now the location of each primary down tubes (ie. the 4 corner posts) will come into play. It would seem a lot to ask for that they too were in identical positions between both models, but pretty damn convenient if that were true. But even if they are placed perfectly, are the tubing o.d. and i.d. the same? I'm guessing the Mk-IV used bigger or thicker wall tubing... Lotsa variables.

I dunno, if it all measures out and is easier to keep the plane straight by replacing the entire head rack, I do see the value in your approach and say why not. Once tubing gets bent and is reformed it loses strength. I most certainly do NOT like the idea of a butt weld, or even a slip tube rosette welded inside, to repair a bent or broken off carry thru tube. Seems replacing the entire headrack with intact carry thru tubes would provide the best strength in that critical area. If approached very carefully and systematically with laser jig for accuracy and proper welding technique, no reason it couldn't work if the parts actually line up. And of course we'll be here to encourage you or B-slap you if you f'n it up! But it's yer plane and my .02 ain't a whole lot when talking about an aeronautical engineering salary!

Oh, and Russ, I would add one last comment... cut once, measure about 100x and do this sober. smile.gif

Thanks Doug, I have measured the wing bushings frt. to back, and diagonaly. All match the Avid setup. The frt. left and rt. door tubes on the KF will slide over the Avid tubes. The rear will have to be welded at my weldment points. 1st. pic. shows rt side damage. 2nd. rt. side butt. 3rd. rear carry thru damage.

post-83-13155912260322_thumb.jpg

post-83-13155912429666_thumb.jpg

post-83-13155913001077_thumb.jpg

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Posted

Thanks Doug, I have measured the wing bushings frt. to back, and diagonaly. All match the Avid setup. The frt. left and rt. door tubes on the KF will slide over the Avid tubes.

Well everyone knows the two models are close kissin' cousins, but that almost seems too good to be true. Interesting to me that the door posts on the older KF are bigger tubes than the newer Mk-IV, go figure. In any event I guess it doesn't get any better than that if you're going to swap tops. Keep us posted on the progress. Pics are good.

P.S. Being nosy now... WTF did you drop a wing landing in a wind shear or hit a barn or something??! :o

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Posted

Well everyone knows the two models are close kissin' cousins, but that almost seems too good to be true. Interesting to me that the door posts on the older KF are bigger tubes than the newer Mk-IV, go figure. In any event I guess it doesn't get any better than that if you're going to swap tops. Keep us posted on the progress. Pics are good.

P.S. Being nosy now... WTF did you drop a wing landing in a wind shear or hit a barn or something??! ohmy.gif

Fence post got in the way. Go figuredunno.gif Russ.

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Posted

Well everyone knows the two models are close kissin' cousins, but that almost seems too good to be true. Interesting to me that the door posts on the older KF are bigger tubes than the newer Mk-IV, go figure. In any event I guess it doesn't get any better than that if you're going to swap tops. Keep us posted on the progress. Pics are good.

P.S. Being nosy now... WTF did you drop a wing landing in a wind shear or hit a barn or something??! ohmy.gif

I asked Dean Wilson about this a couple years ago. His answer was when KF started they did not have any real engineers looking over things so when something came up that may be an issue, instead of adding a small brace or something, they just threw bigger heavier tubes at everything, hence the dramatic weight increase from say a model I to a model IV KF.. after that, they really started building alot bigger airframe and adding heavier engines etc to account for the weight increase. They also got some engineers on board around then too to oversee the design changes.

:BC:

Fence post got in the way. Go figuredunno.gif Russ.

Bet its that same S.O.B. that put a ditch in front of Doug! I say we have a few drinks and go find that sumbitch that keeps putting stuff infront of our planes and beat his ass!

:BC:

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Posted

I asked Dean Wilson about this a couple years ago. His answer was when KF started they did not have any real engineers looking over things so when something came up that may be an issue, instead of adding a small brace or something, they just threw bigger heavier tubes at everything, hence the dramatic weight increase from say a model I to a model IV KF.. after that, they really started building alot bigger airframe and adding heavier engines etc to account for the weight increase. They also got some engineers on board around then too to oversee the design changes.

BC.gif

Bet its that same S.O.B. that put a ditch in front of Doug! I say we have a few drinks and go find that sumbitch that keeps putting stuff infront of our planes and beat his ass!

BC.gif

I'll drink to that, or anything else.party.gif

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Posted

I'll drink to that, or anything else.party.gif

Me Too!!

post-219-13158742154581_thumb.jpg

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Posted

Me Too!!

Words to live by my friend!

:BC:

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