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Old 09-04-2020, 12:24 PM
luke strawwalker's Avatar
luke strawwalker luke strawwalker is offline
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Join Date: Dec 2007
Location: Needville and Shiner, TX
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Quote:
Originally Posted by jeffyjeep
PLEASE tell me what #13 is. Is it a rocket motor?

Looks like a scale model of one of their solid rocket motors for a missile... maybe Minuteman 2/3 upper stage?? I know they used a four nozzle exhaust and thrust termination ports at the top to eliminate the "tailoff" of solid rocket motor thrust as it reaches burnout, which affects the speed of the missile and therefore the ACCURACY of putting the weapon target, particularly without a "post boost vehicle" to perform the final velocity trim of the warhead(s) before releasing them... The velocity has to be *just right*-- if it's under the desired velocity the warhead(s) will fall short of the target (assuming the trajectory is correct) and if it's HIGHER than the desired velocity the warheads will "go long" or overshoot the target... That's why the Atlas used the vernier engines-- allowed it to "trim" the velocity by shutting down the powerful sustainer engine just shy of the desired velocity, and then "creeping up to" the desired velocity with the much lower thrust (thus lower acceleration rate) vernier engines, thus improving accuracy.

BTW there's a view of one laying in the desert from some missile test in an Airwolf episode ("Firestorm"). You can clearly see the four nozzles and the thrust termination ports near the top. Lots of solid rocket missiles used thrust termination ports in the front to counteract the thrust tail-off as the motor burned out, where velocity trim was particularly important.

Later! OL J R
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