In our final days of Semroc 1.0, we were working on several new types of engines. One broke the propellant into sections divided by delays and another had an initial delay followed by propellant then the normal end delay. The first type sounded like a multistage but had higher altitudes. The second was for an upper stage sustainer.

The booster would ignite the delay as it staged. The sustainer would continue for 1 or 2 seconds coasting and slowing until the main propellant started. At this point it was much higher and going slower (with much less drag) as the main charge started. The sustainer did not have an initial spike so it burned at a lower thrust for a longer period. The slight pressure should also help base drag during the delay during staging.

I ran Rocksim on an A1.5-0 to A1.4-4/7 combination on a 10mm 2 stage and it sims to almost 2800 feet(850 meters). The NAR record is 731 meters for B altitude. The -4/7 means it delays 4 seconds before main burn then a 7 second delay before ejection. This is not for the faint of heart or heavy rockets (or non-vertical flights!)

A1.5-0 to A1.4-4/7

BECO v=350 ft/sec alt=300 ft
- 4 second delay - - 0 delay -
SEIGN v=72 ft/sec alt=1100 ft
SECO v=600 ft/sec alt=1800 feet
Apogee v=0 ft/sec alt=2800 ft

A1-5-0 to A1.5-7

BECO v=350 ft/sec
-no delay-
SEIGN - same as BECO
SECO v=700 ft/sec alt=1300 ft
Apogee v=0 ft/sec alt=2300 ft (500 feet less altitude)

Problem is in seeing a 10mm rocket at 2800 ft!

__________________
Carl McLawhorn
NAR#4717 L2
semroc.com