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Square bulkhead in a round skin

RV10Rob

RV10Rob

Well Known Member
The F-1011 bulkhead doesn't fit well into the tailcone bottom skin. The plans show the sides of the bulkhead as curved, but they're definitely straight.

bulkhead.JPG


Anyone else come across this problem? I've sent an email to Van's, and I'll let everyone know what they say. I figure I'll probably end up trimming some of the sides (similar to the HS nose ribs), but I'm curious if there's something else I should consider.

-Rob
 
Definitely let us know what you find. That step isn't too far down the road for me.

Phil
 
Quick reply from Bruce at Van's: it's okay to modify the bulkhead to make it fit better.

I found a pic of Mark Lanier's modification, which looks promising: http://www.lanier-rv10.com/Empennage-Tailcone/2006-09-07_10_08_01a.jpg

Looking at my original picture, I'd say not only is it okay to modify the bulkhead, but it's absolutely necessary. Has anyone completed the tailcone without such a modification? It certainly doesn't look like mine can be riveted as-is.

-Rob
 
fitting curves

I used a scotchbrite deburring wheel to round the corners as they would contact the surface -- did this on my ribs, too, where the tabs were flatter or had protruding edges. This technique worked well for me.
 
RV10Rob said:
The F-1011 bulkhead doesn't fit well into the tailcone bottom skin. The plans show the sides of the bulkhead as curved, but they're definitely straight.

bulkhead.JPG


Anyone else come across this problem? I've sent an email to Van's, and I'll let everyone know what they say. I figure I'll probably end up trimming some of the sides (similar to the HS nose ribs), but I'm curious if there's something else I should consider.

-Rob
Click to expand...

Rob, Use Liquid Shim. This is what I used at United Airlines. Paste it on,
cleco near affected area, let it dry, and then shoot the rivets.. Don't grind or sand on your rib as this will damage it and remove structual intergruty. http://www.aerospace.henkel.com/cps...GHE&BU=ut&countryCode=us&redDotUID=0000000IS8
 
Intresting. I looked around online (without luck) to see if I could find some places to purchase. Do you know who sells it?
 
The aerospace group of Henkel

NORTH AMERICA

Aerospace - Structural Adhesives
2850 Willow Pass Road
P. O. Box 312
Bay Point, CA 94565-0031 USA
Tel: 925.458.8000
Fax: 925.458.8030

Technical Support: [email protected]
Literature Requests: [email protected]
Health & Safety: [email protected]
Customer Service: [email protected]

Aerospace - Surface Treatments
32100 Stephenson Hwy.
Madison Heights, MI 48071 USA
Tel: 248.583.9300
Fax: 248.588.0486

Also Aeropoxy has a variation of this WWW.ptm-w.com Just tell them you need a liquid shim like Hysol 934
 
I used the wheel to trim the tabs but also put tabs on a wheel and bent them to fit the curvature better that they would have.
 
I cheated.

I bought the back five fuselage bulkheads from Underwood Aircraft (no longer in business in) they were made out of Cond-O and hydro formed without notches and fully radiused where required. After they were made they were heat treated to t-3 condition.

I did this in 1991 when I had NO money, so he bought a bunch of hardware and then I bought his bulkheads and all the tank ribs that are were made in the same manner. It was 98 before I got the tail kit. So that was an on faith purchase.

So far I'm just blabbing. So maybe this will help.

If I had to use your bulkheads I would get or make the right dolly or hardwood blocks and use a the right super smooth faced hammers to put the radius where it belongs. (a lot of work) you can re form that small amount of sheet as long as you do not overwork it. It's like fluting, it does not wreck the metal unless over done.

If you can find an old timer that really knows his stuff he could slap them into shape with lead straps and a form. (advanced lesson).

The fill stuff will work too. the thing I would be most concerned in any case is not gouging or scratching the inside of the tailcone skin. This can be a pretty highly stressed area, even more so if its a tail dragger. De-burr and smooth the edges really good before you even get it close to the skin.

Have fun and best wishes.
 
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