Mechanical Engineering - Compressors, Gas Dynamics and Gas Turbines - Discussion


A rocket works with maximum overall efficiency when air-craft velocity is __________ the jet velocity.

[A]. equal to
[B]. one-half
[C]. double

Answer: Option B


No answer description available for this question.

Rekha said: (Feb 4, 2013)  
Rocket is a non air breathing engine, which doesn't depends on air.

It depends only on jet velocity. So jet velocity should be more than its aircraft velocity in this case.

Manoj said: (Oct 20, 2013)  
According to kelvin planks statement we can't obtain the 100% efficiency. So we can't convert 100% work in another 100% work (i.e 100% velocity to another 100% velocity). It should be less then 100%.

Anuj said: (Jun 17, 2014)  
It should be equal to because for maximum efficiency the aircraft should move to its maximum velocity. As we know,

F = m*(vj-vi).

Aravindh.M said: (Aug 2, 2014)  
Sigma = u/cj;
For maximum sigma = 0.5, So 1/2.

Mahaboobbasha said: (Sep 28, 2016)  
Absolute velocity of a non-air breathing rocks jet velocity is always greater than its air jet velocity.

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.