Nozzle efficiency is the kinetic energy of the exhaust divided by the energy available in the exhaust gases expanding from combustion pressure to exit pressure. The nozzle efficiency is high when the nozzle has a smooth bell shape. The nozzle efficiency is higher still when the heat of the exhaust nozzle is not allowed to escape; either because, as is usually the case, it is preheating the fuel or rarely because the nozzle is made of an insulated heat resistant material. The nozzle efficiency can be used along with the expanded change to calculate the expanded velocity.

expanded velocity = sqrt( 2.0 * expanded change * nozzle efficiency )
 
 

This is used in astropolis.html, bipropellantrocket, tripropellant rocket, pumped rocket and rocket cost.
 
 

Feedback   Free Electronic Nation Home    Rocket   GNU Free Documentation License