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Avid C HH wing build 101

93 posts in this topic

Posted (edited)

Yessir, 35 1/2" c-c! On the intial glue, there are only 2 long ribs to be glued. The remaining 3 are 2 trailing edge ribs behind the tank and the tip rib. It's gonna be critical to get these first ones right! Also, there are 3/32" holes drilled in the left wing spars. These were drilled for a drag tube that won't go there, the fuel tank goes there instead. Guess they kinda missed that! Any ideas what to do about those holes. I was gonna put rivets in 'em, but a friend said that they may rub a hole in the tank.  He said JB weld, but I'm thinkin'........Ideas?

Wyatt

Edited by 3CW
Wanted to add. Went flyin' in the Challenger, beautiful, but rougher than a cob!

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Posted

I don't know how the Avid tanks fit, but on my Kitfox tanks they fit loose enough that you are supposed to put some GE Silicone II between the spars and the tanks, so rivets put in the holes would not be rubbing the tank.   EDMO

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Posted

Yessir, 35 1/2" c-c! On the intial glue, there are only 2 long ribs to be glued. The remaining 3 are 2 trailing edge ribs behind the tank and the tip rib. It's gonna be critical to get these first ones right! Also, there are 3/32" holes drilled in the left wing spars. These were drilled for a drag tube that won't go there, the fuel tank goes there instead. Guess they kinda missed that! Any ideas what to do about those holes. I was gonna put rivets in 'em, but a friend said that they may rub a hole in the tank.  He said JB weld, but I'm thinkin'........Ideas?

Wyatt

I agree with ED, SS Rivit there should be plenty of clearance

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Posted

Howdy boys! 

I was gone, but now I'm back at it! Have the ribs glued to the spars with a 3/4" washout and have the strut attachments fit. 80" center of the bolt holes to the root end of the spars. I also have the fuselage attachment elevated above the spars 36" c-c. Boys, I got to tell you, I'm gunny about pokin' the holes in the spars! Those are the only measurements that I have. Is there anything else I would need to check? I have the attachments held in place with hose clamps and have 1/4" of thread showin' at the rod end. I really wish the other strut had adjustment too.

Tomorrow, I figure on setting up the spar stiffeners with 4 pieces of 1/4"X 3/4" birch plywood to make an"I" beam. What would be easiest way to profile the stiffener to fit the I.D. of the spar? I'll be using Poly-Fiber epoxy varnish for a sealer. The way I see it, the only thing that holds the stiffener in place are the rivets from the spar attachment. Ain't a lot, but I guess it's enough. 

Well, that's enough to keep me busy for a bit! 

Keep me straight!

Wyatt

About forgot! Can I buy a mounting for my wing tip position light or would I have to make it?

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Posted (edited)

Kitfox sells the light mount and you can make it work on the Avid tips.  I've got a new set I would sell for $20 plus shipping.  EDMO

Edited by EDMO

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Posted (edited)

Otherwise you can cut a small piece of aluminum slightly bigger than your light then sand a flat spot on your wing tip, and glue the aluminum onto the wing tip, then fill the edges in with hysol and shape it into the wingtip,

and nice work keep it up

Edited by TJay
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Posted

Hey Ed!

SOLD! PM me your address 'n I'll send the money!

Wyatt

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Posted

Wyatt,

Mailed today 6 April - got tracking number too.

EdMO

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Posted

Thanks Ed! Put the check in the box, but the mailman must've come early. Oh yeah! Checks in the mail! 

Beefed up the spar stiffeners today. Take note of the clamps. Thanks JimChuk! I'll be workin' on fittin' them in the spars. The plan is to use a sanding pad on a grinder and just go slow. Any other ideas would be appreciated! Looks like a long process to me.

Wyatt

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Posted (edited)

Wyatt,  One of the Avid builders I watched took a piece of 3/4" conduit and taped a rag to the end of it - gobbed some 9460 on it and CAREFULLY put it in the top and bottom areas inside the spar and swabbed the glue in the right area before inserting his plywood insert.  I am not a fan of the plywood inserts, so I bought some 5 foot long extruded aluminum I-beam inserts from Just Aircraft in case I build more wings.  They are like the Kitfox inserts, only cheaper. 

In case you haven't thought of it, some epoxy spar varnish on the inserts will protect them, just like protecting the ribs.   EDMO

Edited by EDMO

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Posted

Ed, would you do me a favor and post a picture of those aluminum stiffeners? If I don't like the result with the wooden stiffeners, I would like to have the option of using the aluminum. Contingency! 

Wyatt

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Posted (edited)

Wyatt,  I don't have a picture to post, but someone posted a picture of one.  There is also Kitfox drawings in Files and Forms of the reinforcement that the UK mandated.  One was just some aluminum the shape of the rib from rear spar to tail tip and bend a 1/2" angle on it where it goes under the ribcap and glue to both sides and rivet it to the rib and tail back to just before the hanger bolts go thru the tail.  I don't agree with rivets shown thru the rib cap.  The UK showed .025 aluminum, I think, but mine are lots thicker because I have more powerful 15" chord flaps and ailerons.  EDMO 

Edited by EDMO

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Posted (edited)

Ed - I think Wyatt was inquiring about the aluminum I-Beam spar stiffener extrusion, not the rib reinforcements. As I understand, the aluminum extrusion can be sourced thru Kitfox Aircraft or Just Aircraft (less expensive), however, they only fit the .065" wall, not .083", spar tubes.

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Edited by dholly
Pic

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Posted (edited)

Ed - I think Wyatt was inquiring about the aluminum I-Beam spar stiffener extrusion, not the rib reinforcements. As I understand, the aluminum extrusion can be sourced thru Kitfox Aircraft or Just Aircraft (less expensive), however, they only fit the .065" wall, not .083", spar tubes.

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Thanks for the correction Doug.  TJay used the Just stiffeners (inserts) in his .083 wall spars - just have to take about .018 off of each side, or .036 off of one side - I don't know which way he cut it down enough to fit.   These are 5 feet long about 10 times better, IMO.   I have a set if you cant get them anywhere else less than $300 for 4 of them.   EDMO

Edited by EDMO

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Posted (edited)

Hi guys!

Feel like I got a good fit on the spar stiffeners. I used the table saw like a planer to true them straight, and shaving them down to the height that was slightly taller than the I.D. of the spar. Then I set the blade to a 10 degree angle and ran them down the 4 corners. Just shaving the stiffeners left burn marks on them. When I sanded out the marks out and tried them, they fit perfectly. Now I'm going to varnish them with Poly-Fiber epoxy varnish. I know, after varnishing, I'm gonna have to do some more sanding since I've got such a good fit without. How many coats would I want on the stiffeners, and the ribs too for all that matter? Another question: Is there any kinda of lube I could use to slide them in place? It just takes time!

,Like I said, I'm gun-shy about drilling the rivet holes for the strut attachments on the spars. I'm thinkini' that I'm gonna leave the attachments hose clamped, attach the wings to the fuselage and drill/cleco the holes in place. I feel like this would insure their exact location. Am I nuts?

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Edited by 3CW
Forgot pics

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Posted

Use baby oil on the aluminum ones, with wood just push harder, And hose clamp the attach bracket on then drill after the wings are rigged,

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Posted

Thanks TJ! I thought that might be the best way.

Wyatt

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Posted (edited)

I would say to try some liquid floor wax - it wont hurt your inserts or struts.  EDMO

Edited by EDMO

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