Selecting Epoxy
I've spent a considerable amount of time contemplating which epoxy system to use. Primarily, I've been familiar with and have used the R&G systems in the past.
However, the project plans necessitate a range of different curing times and temperature resistances, for which I couldn't find an adequate fit within the R&G product lines. Furthermore, there's a mantra repeated by both the designer, Serge Pennec, and many builders:
Stick to the plan!
That's precisely what I intended to do. The plans and documentation specify the Sicomin SR 1500 system as the ubiquitous all-around choice, mainly for all wood bonding, with occasional use of the stronger (and much more expensive) SR 1700.
There are two primary issues with these specified systems:
- The distributor in Spain informed me that the SR 1500 has been discontinued, and Sicomin is only selling remaining stock until it's depleted. This, clearly, does not constitute a reliable source for purchasing material.
- While both systems are toxic, the SR 1700 is listed for sale only to professionals. Some builders have already reported difficulties when attempting to order this system.
Consequently, we need alternatives. After all, the world doesn't stand still, and one of the huge benefits of experimental aircraft is the ability to incorporate innovations much faster.
After several discussions with Mel Composites and
the aircraft designer, I decided to use the Sicomin SR Greenpoxy 33 with the SD 47xx hardener.
It was recommended by Sicomin as an alternative and also accepted by Serge Pennec.
SR Greenpoxy 33 / SD 47xx
The SR Greenpoxy 33 boasts excellent mechanical properties, exceeding those of the SR 1500 at
a comparable price. It also features a high glass transition temperature, up to 100°C.
This is particularly advantageous for us in the south, with our hot summer days, as it even
allows us to paint the plane in colors other than white. Ferrari red... here we come!