sustainers

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Matt

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hey guys i need some help i very confused what a sustainers ive heard all this stuff about a sustainers coming to pressure but usually only motors do that or is it a part of a motor could some one tell me what a sustainers is and how it effects the rocket
 
A sustainer is the upper stage of a two-stage rocket. The only difference between the sustainer in a high power rocket and a sustainer in a low power rocket is that the high power rocket usually has to carry some sort of mechanism to light the upper (or sustainer) motor. This is because there is no way to directly stage composites. A timer usually does the trick.

Why should you be worried about sustainer pressurization? Well, a composite rocket motor can't operate underneath atmospheric pressure-- it has to generate some internal chamber pressure for the propellant to create force with the exhaust gases. A larger motor takes more time and a bigger igniter to come up to pressure. I've seen motors light almost instantly (ask Bill Seiders) or motors not light at all (chuffing, misfires). If you have a large motor in the sustainer of your rocket and it takes a long time to come up to pressure, you will have a much longer staging delay and the rocket may fly off course.

HTH.
 
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