Midget70 - 2.2 inch (BT-70) Midget upscale

Midget 70
2.2" (BT-70) Upscale

This Midget variant was built using BT-70 (2.2") tubing. Originally, it existed only in upper stage form, but provisions for mating a booster were included.

The nosecone is turned from cedar, and that should give it the extra noseweight needed for stability. The white paint is RustOleum's epoxy enamel while the black is regular RustOleum.

At this scale, the weight is too great for using a black powder (D12) booster motor, and some other solution is needed.

The aft end tapers to BT-60 with a 24mm motor mount. The booster can be attached to the sustainer using a BT-60 coupler.

At some point, the nosecone got dinged up and I painted it red. Here's a great shot of a single-stage liftoff.

Photo courtesy of Tim Sapp

Here's another cool liftoff pic.

I finally built a booster for it. Three B6 or C6 motors along with a central D12 work great. A burn string holds it on the pad to ensure the center motor lights. This is necessary since only the center motor lights the upper stage. The outboard tubes are beveled on their forward ends to join the BT-60 which mates to the sustainer tailcone.

Here it is prior to a launch with a full complement of booster motors. At the time, I was using a clip-whip. Since then, I have started using lead extenders on the ignitors. This eliminates the aliigator clips which tend to be unreliable in cluster situations.

Here's a decent shot of the cluster coming up to pressure. It put in a great flight.

It has clearly moved up from the burn stick. Not sure if it's the burn string or an ignitor lead hanging down below the rocket.

12-24-2008