EXPjawa
Well-Known Member
I'm investigating building a semi-scale, 1.6" sized model of the Nike-Nike Smoke that we'd discussed elsewhere. Basically, from what I can gather, the rocket takes the Nike Smoke that we all know & love and adds a second Nike booster to turn it into a 2-stage rocket for high altitude use. Of course, it would be easy to simply build a long rocket that was detailed to look like a 2-stage model, but flies single stage only (like my Estes Terrier-Sandhawk). But I'd really like to make it a proper two-stage. That means gap staging. For the design I've come up with, there's a little less than 10" from the front of the booster motor case(s) to the nozzle of the sustainer motor.
Basically, what I'd like to do is cluster three 18mm motors in a BT-60 tube, two of which will duct their blow-through up to the sustainer by way of near full length stuffer tubes, and the third will carry a delay and deploy a parachute after the booster is falling away. The sustainer will also have an 18mm mount; anything bigger that far forward requires serious nose weight to balance. My questions are thus: 1) is 10" too far to allow reliable ignition of a gap-staged sustainer motor? And 2) if I leave the space between the three booster motor mount tubes open all the way back, does that provide sufficient venting for the air in the forward booster to escape? Air flow would be up the stuffer tubes, into the chamber just below the nozzle, and then back out between the tubes to the rear. Or, should it have vent ports near the top of the booster to simplify the airflow?
Basically, what I'd like to do is cluster three 18mm motors in a BT-60 tube, two of which will duct their blow-through up to the sustainer by way of near full length stuffer tubes, and the third will carry a delay and deploy a parachute after the booster is falling away. The sustainer will also have an 18mm mount; anything bigger that far forward requires serious nose weight to balance. My questions are thus: 1) is 10" too far to allow reliable ignition of a gap-staged sustainer motor? And 2) if I leave the space between the three booster motor mount tubes open all the way back, does that provide sufficient venting for the air in the forward booster to escape? Air flow would be up the stuffer tubes, into the chamber just below the nozzle, and then back out between the tubes to the rear. Or, should it have vent ports near the top of the booster to simplify the airflow?