Thrust chamber velocity

treddie

Hello.

I am trying to find the thrust chamber flow velocity for a rocket engine, but no literature seems to be able to come up with a solution for this. The best I have found is "Rocket Propulsion Elements" which states that the value probably lies somewhere between 200-400 ft/sec.

But in my tests, I come up with something more along the lines of 1500 ft/sec for the Saturn V F-1 engine. This is either wrong, or the range of 200-400 ft/sec is unreliable. I think my result is wrong because it should be a LOT slower than the approximate Mach 1 at the throat.

The reason I am fixated on this chamber flow velocity is that it seems to be my only ticket to getting the thrust chamber radius (and from that and other data, chamber cylinder length). I have tried the chamber length approximation (for the cylindrical portion) of Lc = EXP(.029LN(Dt)^2 + .47LN(Dt) + 1.94), in (cm), (from http://www.braeunig.us/space/propuls.htm), but this only seems to work well for large engines. When I tried it for a small, Apollo SM/LM R-4D thruster, it was way too large (not even in the ball park, really).

treddie

ANY thruster-heads out there?