Here is the Airframe of the larger of the three Lego Rockets set next to the former largtest. The former used to fly on a 38mm Aerotech J-420 Redline. It had really good flight characteristics, even stable in the windiest of conditions.

Finally making time to work on my rockets, well before the night before the launch. Brought about by a good couple of snow days. Here is the first mock up of my fin design. Originally it was about a third as long and with out cross supports. This should make for a stronger and lighter fin. The increased size ought to give more stability to the rocket. But with drag caused by the thickness of the bricks the rocket should be rather stable any ways.