Thanks very much to all of you. I will PDF your advice and save it up for Mark 2!

A few comments:

1. David has me worried about the nose stability issue. I will cut into the cheek skin and reinforce it with hardwood or carbon.

2. The AMA review cautioned against using a prop larger than 11" on the Kaos because the gyro effect would cause tail wag on vertical lines. My goal is to replicate the stock piston performance, not necessarily to improve on it - on Mark 1 at least.

3. The Firepower 40 is the only motor I could find on the planet which combines a 42mm diameter with 700W rating and low Kv (about 625 from bench tests). Nothing bigger than 42mm will front-mount in the nose of the Kaos.

4. The whole nose-mount thing began when I saw Franny Brodigan's gorgeous conversion of the Bridi Vagabond, which can be found in the link below. I thought I had to go nose-mount to imitate this. Now Franny is obviously a greater craftswoman than many of us guys can aspire to. So for Mark 2 I may have to hack out the nose for an X-mount instead.

http://www.frannybrodigan.com/Vagabond.asp