rv6ejguy
Well-Known Member
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.
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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.
Wow! Next thing you know, someone will start building airplanes with fiberglass and glue.
BJC
BJC
Bonded in the same way as the BD4?
rv6ejguy
Well-Known Member
Yup, Bede designed the Yankee etc.tubular spar, bonded skins. Have stood the test of time with millions of hours collectively.
TarDevil
Well-Known Member
Couple guys at the FBO I managed owned a Yankee they were afraid to fly. One mentioned to me, "It needs to be flown."
So I did. One of my absolute favorite two seat production aircraft.
So I did. One of my absolute favorite two seat production aircraft.
TFF
Well-Known Member
This is probably the most expensive Yankee in existence
TFF
Well-Known Member
David L. Downey
Well-Known Member
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
Well-Known Member
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
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
Exactly. Structural aluminium bonding is too dependant on proper cleaning from physical residues aka oil fingers and/or proper oxide layer management.
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
Well-Known Member
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
Well-Known Member
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
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..
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..
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.
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.
Interesting article , certainly the begin which explains how bonding works . https://www.compositesworld.com/cdn/cms/Fokker_Glare.pdf
The article mentions anodizing as a means of bond preparation and gives some information why it is a durable process.
