Am I the only one who's noticed that when two engine are in a cluster, the circle that encloses them has a lot of wasted space? I doubt it. Am I the only one who's thought that a body tube with an elliptical cross-section would contain a two engine cluster so much more efficiently? Or am I just the only one stupid enough to take the idea seriously? I've worked out how I'll do it. I've figured out how to determine a safe value for the CP so the final swing test will go smoothly. The 3D printed nose cone and laser cut balsa parts are designed. An awesome paint scheme is... not coming to mind; I always have trouble with that part. The cluster will be two 24 x 95 mm, which provides me a pretty good range of total impulse options, from a pair of Estes C11's (21.8 Ns) to a pair of Aerotech F32's (153.8 Ns.) Anyway, I'm typing on my tablet because my real computer is down at the moment, and may not be back up for a couple of days. I have the cone modeled in OpenSCAD, so I started to do the rest just to have some screenshots to post; I may have some pictures in a few days.