This required the development of a mercury-switch activated onboard ignition circuit, which fires a capacitor holding 9 volts, thus activating a flashbulb taped to a Teflon-jacketed fuse which is inserted into the top stage motor core. For a while Aerotech did make a few special composite booster motors which could be staged directly, but the system was not very reliable, and vastly limited one's engine choices. No full-H motors with direct-staging capability were available. These two pics portray very early prototypes, when I was shaking down the rocket's top stage alone. Good to go!

This is the rocket, which I used to develop the onboard flashbulb-ignition circuit. It uses BT-60 Estes tubing, and I initially called it the E-Squared, as the Aerotech E28 was my motor of choice. There were some setbacks, but overall the rocket was a great learning tool.

For instance, it taught me that choosing a proper ejection delay becomes very tricky with staged rockets. This photo displays the repair method I developed to repair "zipper tears" made by the shock cord when the 'chute deploys at high speed.

In the end, I had to rechristen the rocket the F-Squared, after successfully flying it on dual F motors (F40 booster and F25 upper). This was a magnificent flight, which was lucky to be recovered! But this rocket seems to have a homing instinct. I repeated the dual-F flight at a monthly NIRA launch, only with F25 booster and F10 upper, and the more efficient thrust profile increased performance even more. Though the flying field was an oversized ball diamond, basically, I caught the rocket as it returned to Earth! Note that this was the maximum legal "model" rocket possible, being well under the weight limits and with a combined thrust potential of 160 n/sec. As far as I know, it was the first, and perhaps still the only such max-profile flight made at a regularly scheduled NIRA launch.

The final version of the H-Squared, using 38mm mm dia heavy-duty airframe tubing and 3/32 fiberglass fins mounted TTW. Alas, my fist attempt at a full-load flight was unsuccessful, with a top-stage ignition failure and the near-total destruction of the rocket.