The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S - Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres)
The air standard efficiency ofan I.C. engine is given by (where r = Compression ratio, and Y = Ratio of specific heats)
The mechanical efficiency (ηm) of the engine is given by
If V1 is the jet velocity and V0 is the vehicle velocity, then the propulsive efficiency of a rocket is given by
If V1 is the jet velocity and V0 is the vehicle velocity, then propulsive efficiency of a turbo-jet engine is