Updates Blue Origin announces the New Glenn Orbital Launch Vehicle

Thunder Chicken said:
That's not deep enough. Merlin can be throttled down to 40% and they can't hover the Falcon 9.

45% of a single BE-4's 550,000 lbf thrust is just under 250,000 lbf or 124 tons of thrust minimum. Total thrust of the booster is 3,850,000 lbf, so the maximum weight of the entire loaded rocket must be less than that. Call it 3 million lbf on the pad. Spitballing a mass fraction is 5% (a rather high number) the empty stage mass would be something like 75 tons. In all probability it is lighter. Unless they are carrying a lot of fuel back to the landing site or managed to get their throttle down to 20% (which would be astounding) or have something else up their sleeve I don't think they'll be hovering this thing.
Click to expand...

5% is a rather low number actually for a rocket, especially first stages. Some have of course achieved it, but usually they are closer to 10%. Also Blue Origin does not seem to optimize their rockets for launch, but more for landing, they are made for falling back to Earth rear end forward and put quite many landing systems on them. I'd say a heavier landing mass is quite likely.

They could actually even increase the dry mass of the first stage by moving typical second stage systems into it, for example engine ignition and staging systems. And make the non-reuseable second stage lighter that way.
 
Found it, 28:16:

"Sustained Thrust to Weight equals 1", with throttling one engine down to 40%. Though he specifically only says constant velocity descent, so it's possible they skip an actual hover.
 
diogom said:
Found it, 28:16:

"Sustained Thrust to Weight equals 1", with throttling one engine down to 40%. Though he specifically only says constant velocity descent, so it's possible they skip an actual hover.
Click to expand...
That how it sounds to me too. It sounds like they will do full thrust on three engines to get it to a low velocity, and then shut down two and throttle one down to 40% to maintain that velocity to touchdown. Instead of trying to hit 0 velocity at 0 altitude, they are going to decelerate to a slow enough touchdown speed and just maintain that to touchdown. I doubt that they will be doing an extended hover like New Shepherd because that is simply a waste of fuel.

So this implies that the New Glenn booster stage at touchdown will weigh 0.4 x 550,000 lbf = 220,000 lbf or 110 tons. Assuming a mass of 3 million pounds on the pad that would be 7.3% of the total wet mass of the stack.
 
https://twitter.com/x/status/1851498623949029778

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