Hmmmmmmm.

 

Well, once again I must prepare for my 320 to come apart at any second...........

 

Dan, et al,

 

I used the old-fashioned, simple method of de-grease (Dupont S-22, no longer available cause of those EPA folks), clean (store-bought "Sunnyside" acetone), sand (no coarser than 80-grit), clean (acetone), always wiping with rolls of "lint-free" Bounty and finally removing bolls of residual lint, thus making me a weevil......................

 

Whilst the appropriate parts (fuelish areas) were bonded with a 3-M industrial cement (number ?, thin is better, fuel proof), the wing bottoms and wing D-section (leading edge) became one as follows:

 

1.  Rib edge nomex was scraped with a screw driver until it was depressed at least 1/4".

 

2.  Clean with acetone.

 

3.  Paint on epoxy and mix the remainder with flox to make? Flox.

 

4.  Flox was then forced into the depression and mounded up.

 

5.  The release-taped part (wing D-section or bottom) was positioned and weighted as though it was to be finally bonded.

 

6.  The cured flox was sanded and bonding surfaces were prepped as above.

 

7.  3-M cement was spread on (and into) both surfaces and parts put together and weighted until cured.  

 

Note that this was pre "cap-strip" (for later ES, IV, etc builders - "flanged" ribs), thus the wing bottoms (holding the potential 4-G weight of fuel) are only attached to the 5/8" wide ribs by a strip of adhesive.  Gee, I remember when my wings were painted and set in the sun the next day for many passerbys to admire - then loaded upside down into a van to return them to the airport.  I was shocked as I looked down the wing and saw enormous bulges between the ribs - Finally the light bulb came on and I pulled the golf tee out of the wing tank vent, relieved by the interminable hiss as the air escaped.  Hmmmm, looks like I don't have any leaks.... I wonder what the pressure was?.  Anyway, My wings are still in one piece after years of abuse.  Preparation is everything.  Squeeze-out is next.  The materials are all pretty good - good enough to hold things together if they are used properly.

 

Believe me, I think the flanged ribs with the large bonding surfaces are better than the old way as long as the surfaces are also well prepared and wetted.  The bad part of large area flox-bonding is the propensity of Jeffco to exotherm.  That is why Hysol is better.  I bet the Legacy skin peeled because there was no wetting of both surfaces before smearing on the flox and then the flox had started to cure (or exotherm) before becoming one with the skin surface.  There is no useful extended working time with the hi-speed Jeffco.  It is useful for small jobs requiring serial construction, but no good for a large construction step.

 

Maybe I can explain some other time how many years it took the skin on my hands to recover from the cracking and dryness because I used to clean my unprotected fingers with acetone.

 

Maybe I can explain some other time why my paint color experiments resulted in the upper surfaces being painted white.

 

Of course, all of that information is buried in the LML archives.