The Estes Mini Mean Machine, or E3M reaches over 200 feet, with 13mm motor power, but it can be up powered to accept 18mm motors and still use 13mm motors with an 18mm to 13mm motor adapter. Leave out the 13mm engine mount that Estes supplies with the kit and use one of the BT-20 to BT-5 centering rings as an engine block. Put a mark 1/4 inch(7mm), from the end, of a used 18mm motor and use as a depth gauge. Glue the engine block in to the BT-20 so that 1/4 inch(7mm) of the 18mm motor remains out of the BT-20, at the mark. Add nose weight, to re-balance the C/G, for the heaviest 18mm motor you can find. Laminate the fins, with printer paper, when using composite motors and assemble the rocket with epoxy, or C/A adhesive for max strength. Use lots of wadding and the E3M should see around 900 feet on a C6-5 and with a D10-8 will see over 1,000 feet. Tape the motors to the BT-20 and have fun with this rockets simple up power mods.