PPRuNe Forums - Megarocket

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- - Megarocket (https://www.pprune.org/space-flight-operations/638063-megarocket.html)

According to the BBC News

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The four RS-25s can generate 1.6 million lbs (7 Meganewtons) of thrust - the force that propels a rocket through the air.

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Originally Posted by tdracer (Post 10970040)

Yellow, that's popular myth, but it was never actually true for any operational rocket.
Think about it - if you needed to burn off fuel to reach the liftoff weight - why not just reduce the starting fuel load?
Thanks wiggy - good to know some sanity remains at NASA. I'm still angry that we're spending tens of billions of dollars to re-create the heavy lift capability we had five decades ago and simply threw away.

As I say, I am happy to be corrected by those who do know about these things.

The myth seemed reasonable to my mind because I assume a rocket engine does not go from ‘zero power’ to stable state ‘top whack’ power instantaneously and that some time was require to go from one state to the other. Using unnecessary, overweight fuel during that power build up stage seemed plausible to me. I suppose a proper myth has to have a large degree of plausibility.

I’m surprised no-one has levered in the expression it isn’t rocket science yet in this thread!

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Originally Posted by yellowtriumph (Post 10970306)

I’m surprised no-one has levered in the expression it isn’t rocket science yet in this thread!

That's because it is rocket science!

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Originally Posted by yellowtriumph (Post 10969889)

... and what will Greta make of all this? Can Nasa designers come up with some electric equivalent that can be plugged in and charged up overnight?

No need,
Hydrogen and LOX only exhaust steam.

Having said that, Methane and LOX produce steam and CO2, so Greta not so happy .

Hmm. All manufacturers in the world: we can make engines smaller, fuel consumption is lower, and power is higher.
Rolls Roys and UK Space Agency: We will try to build a nuclear rocket engine to reduce the mass of the rockets.
NASA: we can connect 4 engines at once.

Quote:

The four RS-25s can generate 1.6 million lbs (7 Meganewtons) of thrust - the force that propels a rocket through the air.

Pretty big difference between "Meganewtons" and "Megatons"