#### phil303

##### New Member

- Joined
- Feb 5, 2010

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So I know the rocket thrust equation as:

T=(dm/dt)*V_e+A_e(P_e-P_a)

where,

dm/dt = the mass flow rate

V_e = exhaust velocity

A_e = Area of exhaust plane

P_e = Exhaust pressure

P_a = Ambient Pressure

But I was bored today and was trying to do the free body diagram for the rocket. And I just can't get the same equation. It's driving me crazy. I can't figure out where I went wrong. Anyway, here's my work.

http://double-chinned.mirror.waffleimages.com/data/e6/e6205fdb65daa7cfb9bb3e7e46de3ee68fb58585.jpg

If anyone can point me in the right direction, it'd be much appreciated!

Edit: Fixed the picture link.

T=(dm/dt)*V_e+A_e(P_e-P_a)

where,

dm/dt = the mass flow rate

V_e = exhaust velocity

A_e = Area of exhaust plane

P_e = Exhaust pressure

P_a = Ambient Pressure

But I was bored today and was trying to do the free body diagram for the rocket. And I just can't get the same equation. It's driving me crazy. I can't figure out where I went wrong. Anyway, here's my work.

http://double-chinned.mirror.waffleimages.com/data/e6/e6205fdb65daa7cfb9bb3e7e46de3ee68fb58585.jpg

If anyone can point me in the right direction, it'd be much appreciated!

Edit: Fixed the picture link.

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