Ejection Charge

[ELBRAZ]

before I go any farther in my madness, I need the opinions of the group. I've got a rear-ejection design that should work for the 60 motor Warloc clone, but would the kinda simultaneous firing of 60 (I hope) ejection charges pressurize the 7.5X30 inch airframe for conventional deployment? If not, has anyone augmented a modrock ejection charge with a few grams of BP?


The picture is of one of the rockets displayed on the missile walk at Ft Sill. Nose is cut off, but I took it for fin, conduit, and details of the strange corrugated bit toward the top. I've got photos of Little John, Honest John, Lance, Lacrosse, Pershing (both models), Sargeant, and Redstone. The paint jobs are really simplified, could be good for Sport Scale if your are neatness challenged like myself. Should I scan them?

 

[Missileman]

I am assuming black powder motors?
I am not sure of smaller sizes but D engines have .86 grams of bp for ejection.
Lets say only 20 of your motors fire ejection charges near the same time. Rounding down to .75 grams each for simplicity that is 15 grams of BP firing ejection.
Whithout calculating it roughly 2 grams should be about enough for that size airframe.
if most of the motors fire you are looking at around 30 to 40 grams.
My concern is if the airframe can withstand the pressure.
Are you using a flashpan?
I saw a 62 motor attempt once but only about 40 or so lit.

 

[ELBRAZ]

Yes, I'm using flashpan. Oh, well. Get the chute out or blow the critter apart is my motto. I hope an overpressure will be avoided since the ejection charges are going to "ripple-fire". The NC will come off when the pressure is high enough, and the remaining charges will just be sound effects. A few pictures of the critter in the flashpan thread in Scratchbuild. Thanks, missileman.

 

[loopy]

You could put a few vent holes in the tube above the motors to vent some of the pressure.

Loopy

 

[powderburner]

If you are worried about too many ejection charges firing at once, while the NC is still in the front of the rocket, then consider changing out a portion of the motors to use longer delay charges. The first wave will eject the NC and recovery system, the remaining motors would be delayed and would 'eject' into an open BT.