Hard shelling

[Autodidact]

I would like to develop a wood/foam construction method that is similar in concept to the Mosquito's plywood/balsa sandwich construction but with foam replacing the balsa. It will take some experiment and study and may not result in a weight saving over normal wood construction, but i think it might be simpler to build than traditional wood. I don't want to talk about why foam/fiberglass is better .

I am concerned here about de-lamination caused by out-gassing of the foam. Is this a legitimate concern? Will hard shelling prevent this? Are there other ways of solving this (potential) problem, like lightening holes through the panels?

My concern with hard shelling is that I can't find a definitive answer as to whether it is a good idea or not. Some people say "good" and some say "not good". Here is a compelling sounding case for "not good", form a Cozy forum, I think:

Thirdly, and worst, you will end up with poorer peel strength, because you will be relying on a mechanical bond to a flat, cured micro surface rather than a chemical/mechanical bond of epoxy to foam, involving a lot more surface area, as with a wet layup over wet micro, as specified in the construction manual.

"One of our builders/fliers heard a loud pop while flying around 13,500 ft"...I also asked if this could have been due to "hard shelling", which doesn't result in as strong a bond as a wet layup over a wet micro filled foam surface...The builder replied that the airplane in question was a Velocity, and the builder had used the "hard shelling" technique.

The bad news was that everywhere the hard shell had filled in a void, even as small as one-eighth inch in diameter and perhaps one-sixteenth inch deep, and everywhere the hard shell had been used to create even a very thin filler layer on top of the foam, the glass skin popped right off the hard shell as clean as a whistle… … Scary!…

What say you guys?

 

[TFF]

 

[Autodidact]

 

[DaveD]

 

[Autodidact]

 

[wizzardworks]

 

[cluttonfred]

 

[BBerson]

 

[Autodidact]

 

[Autodidact]

 

[Himat]

 

[Autodidact]

 

[Himat]

 

[Autodidact]

 

[Autodidact]

 

[DeepStall]

 

[Autodidact]

 

[BBerson]

 

[Aircar]

 

[Autodidact]