Really nice, John! I'd love to build one some day so be sure to do a kit or plan pack with wraps!

The reason the engines look that way is because he had to use BT-5 for the motor mounts.

As for finless stability, think bottle rocket. CG in front of CP. It doesn't matter whether it's "pushed or pulled". If that was all that mattered, bottle rockets would swap ends at burnout.

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I love sanding.