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rv6ejguy

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Jun 26, 2012
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I like the B4c a lot, but I am not sure that I could trusted the bonded wing. Might be great, but is a little too far out on the edge for me.
I had lots of time in a very old (30+ years and 6000+ hour) Grumman Tiger. Nothing wrong with the bonded wing there. Pretty proven tech.
 

lelievre12

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Jul 15, 2020
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I think the Beechcraft Musketeer/Sundowner/Sierra had bonded wings as well. I know my one had no skin rivets on the leading edges.
 

David L. Downey

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Aug 7, 2019
Messages
93
Bonded in the same way as the BD4?
Simple question...extremely complex answer. Tersely stated, no, the home shop bonding process does not equal the production method. For performance or durability.
On a different tack, I have always found it intriguing that all the screw/nut joints in the fuselage truss violate the basic rule to avoid knife edges in structural 2 detail fastened joints! If memory serves, the countersink for the screw is full depth on the outer detail and partial depth on the inner detail. Does make a superbly keyed installation though - and I never heard of a crack coming from one of the fastener locations.
 

David L. Downey

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Aug 7, 2019
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93
Interesting side note.
Way back when, the USAF research lab in Dayton at Wright Pat found that among the best "field" aluminum bonds resulted from a final scour/abrade using the actual adhesive during the process. Abrade, immediately wipe surface clean (no solvent!) Reapply adhesive, join,clamp, allow to cure.
Theory was that the surface was final cleaned/prepped with no oxygen exposure and therefore the oxides that can cause poor bonding never had the chance to form.
Someday I will probably try to verify he assumption if I live long enough
 

stanislavz

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ersely stated, no, the home shop bonding process does not equal the production method. For performance or durability.
Exactly. Structural aluminium bonding is too dependant on proper cleaning from physical residues aka oil fingers and/or proper oxide layer management.
 

ToddK

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Jan 13, 2016
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430
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The Real Texas
Somehow I just don’t see the guys at Grumman sanding the bare aluminum spar and prosealing the thing together and calling it a day.
 

TFF

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Apr 28, 2010
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14,192
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Memphis, TN
The process is close. Grumman American, remember it was an acquisition of American Aircraft not the guys that came up with the Wildcat, used epoxy. They also screwed up in 1975 and tried to change the epoxy which caused an AD. Pro seal is dummy proof in the tubes. It sticks to everything practically. All you have to do is have wide enough goop slopped on to hold. In away , the AA aircraft wings were like the original buckets of the BD4. They were modular in concept but made in two sections. The brain behind all of this is pretty consistent. Modern BD has to live in the edge of the past brilliance and lowness. You can tell the determination to stay open.
 

Bill-Higdon

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Joined
Feb 6, 2011
Messages
1,014
Location
Salem, Oregon, USA
Interesting side note.
Way back when, the USAF research lab in Dayton at Wright Pat found that among the best "field" aluminum bonds resulted from a final scour/abrade using the actual adhesive during the process. Abrade, immediately wipe surface clean (no solvent!) Reapply adhesive, join,clamp, allow to cure.
Theory was that the surface was final cleaned/prepped with no oxygen exposure and therefore the oxides that can cause poor bonding never had the chance to form.
Someday I will probably try to verify he assumption if I live long enough
This is the process Goodyear used for repairs to their honeycomb "Shelters back in the 60's & 70's, I was trained on it when I worked AGE repair on the "Photo Van" shelter repair in 1973
 

stanislavz

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Aug 21, 2016
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Lt
There exist one non purist way to solder aluminium - you flux is mineral oil with some grinding paste and normal flux. You put it on you metal. And with soldering iron under paste grind away oxide. And flux with solder will stick to new aluminium surface.

Same could be tried with epoxy - sloow epoxy with grinding powder - you grind you parts under it, wipe with rag and add you layups. No exposure to oxygen..
 

stanislavz

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Aug 21, 2016
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Lt
Some thread stealing.

A way to avoid dry to dry bond. For open layouts/layout between foils

You lay you part, last on layer is wetted using epoxy with slow hardener. Which will gel after 3-4 h, and fully cure after 2-4 days.

Or after you layout and squezing extra epoxy - brush some epoxy on places to be bonded.

Just an idea.
 
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