Can Vmg exceed the V of a jet exhaust?

[awblain]

Re:51 why a nozzle?

Nozzles are necessary evils?

Rocket expansion nozzles lose a lot of thrust, but they are necessary to be able to gimbal the exhaust accurately and ensure control of the whole vehicle. Also, as stated by Mr Optimistic, straight release of the 1000 atmosphere through a 2-foot hole would be an explosion. Stable combustion requires a steady flow. Also, they reduce and control instabilities in the shear layer between the exhaust and air and prevent acoustic damage.

The likely 2:1 thrust loss I quoted previously for the shuttle main engine is much much more than in a jet engine. It might be 800,000lb, but acting over the 2.4-m wide, 3-m long nozzle, it's only a viscous force of ~ 6 lb / square in. The exhaust speeds and pressures in even a military engine are much less, and so is the jetpipe surface area, leading to a much smaller fractional loss.

Note to ChristiaanJ: I accept this is ignoring changes in internal energy in the gas from temperature-pressure-density, the careful manipulation of which can give an efficiency gain.