The cryogenic engine cycles (see figure) normally used are gas generator cycle, staged combustion cycle and expander mode cycle.
Thanx for the excellent post, it was really very helpful n very detailed explanation in very simple language...
I'll try to summarize what i have understood so far on this topic here, plz point out any deficiencies u notice
What i have understood so far is SCC engines r the most complicated but the most efficient engines n Russia leads this tech with its RD180 n r generally used at 2nd or 1st stage to get the rocket outta Earth's atmosphere as they r highly efficient n have high thrust to weight ratio. Most countries r still trying to catch up with the Russians here. These engines r so efficient that they considerably reduce the additional booster requirement of the rocket.(Indian eg.- SC200)
Then comes the expander engines which r also complicated(but not as much as SCC) n here the US leads the package with its RL10 these r also efficient engines n r generally used at the upper stage to lift the satellites to its final position. These r smallest in size n have max thrust limitation(around 300kn).
The smaller size helps in reducing the over all weight of the upper payload making the rocket lighter in size(in comparision to using Gas Generator Engines in upper stage) Although these r smaller in size n have limited thrust but provide good thrust to weight ratio good enough to lift the satelittes at upper stage.
But most countries r either not able to make them small enough (RL10 vs RD56) to provide the necessary thrust at the upper stage.(Indian eg.- CE7.5)
The last one r the Gas Generator engines which r least complicated n can be easily expended to provide higher thrust at upper stage(as high as 1300kn) but r not very efficient(bcoz the Gas generated in not reused again) resulting in lower thrust to weight ratio.
But these r the most widely used engines world wide n r used by majority of the nations(Except US n Russia for upper stage). France leads it with there Vulcan Engine. (Indian eg.- CE20 n CE60).
Even though they provide high thrust but at the same time increased weight too but most countries prefer them due to their simplicity. But they have to use much bigger engines to produce the required T/W ratio(In comparision to Expander Engines).
Plz provide ur views on my understanding.
@
S-DUCT i would like to hear ur comments too on my explanation...
