Originally Posted by FlyBack

Black Shire

In all three configurations both motors are ignited at the same time (like a cluster). A hold back system is required. The D5-P orbiter motor burns slightly longer than the E9-4 booster motor. I guess that makes it a 1 1/2 stage rocket. Separation occurs when the rear ejection parachute deploys from the booster stage. The orbiter motor remains with the orbiter.

The two motors used have different impulses and average thrusts. However, their thrust/time curves have nearly identical shapes. That characteristic is what allows me to meet the conditions stated above. As a consequence, they have different offsets from the vertical C.G. and also different thrust line angles. Getting that part right is a real B... err, challenge.

Regards,

DJ Miller