I'm considering using alphatic resin to glue the shear webs on my Chrysalis. My understanding is that A/R (properly applied) has a stronger strength to weight ratio then C/A. Any thoughts?

From : Don Stackhouse

Aliphatic resin is definitely better for this application than C/A. The only drawbacks are the longer drying time, and the need for more than one kind of glue. When we wrote the Chrysalis HLG instructions we were trying to keep things simple and fast. However, if I was writing the Chrysalis instructions today, I would recommend aliphatic resin or other "white" glues for the shear webs.

In fact, come to think of it, I did just finish writing the 2-meter Chrysalis instructions, and in those I did specify white glue for the shear webs! ;-)

I've come to the conclusion that part of our job in designing a built-up beginner's model is to provide training in proper building methods, including teaching which kinds of glues are preferred for which applications. With this in mind, the 2-meter Chrysalis can be built successfully with only medium C/A (and we say so in the instructions), but we recommend five different types of glue (fast and slow C/A, 5 and 15 minute epoxies, and of course white glue) for different steps of construction. For critical wood-to-wood joints requiring strength and toughness (such as the wing spars), we recommend white glues such as aliphatic resin. We have little notes in each step indicating which type of glue to use.

Epoxies have better strength than aliphatics, but the aliphatics do a better job of soaking down into the wood to provide a deeper bond. C/A's are more brittle than either aliphatics or epoxies. Although they soak in better than epoxies, they don't soak in as well as the aliphatics (soaking takes time, and C/A cures too quickly to allow that to happen). Thin C/A improves the soaking-in properties, but tends to make the joint brittle, with very poor toughness. For this application, the aliphatics provide the best combination of properties.

Don Stackhouse
DJ Aerotech