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Booster will either do a partial return and land in the Gulf of Mexico or do a full return with a catch attempt

That's cool - hope we get to watch it either way (Like, they take out one of the Drone ships and land just off it, if it is a water landing)

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Ship will reach about 250 km in altitude, then powered landing in the Pacific

Why so high?  Is that due to ballistic nature of the flight?

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31 minutes ago, JoeSchmuckatelli said:

Why so high?  Is that due to ballistic nature of the flight?

My guess is it is doing a burn with the same deltaV of a circular orbit insertion, but with an elliptical trajectory that carries it back into the atmosphere.

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Posted (edited)

Wow, the finished Raptor 2 engines are so clean (of extraneous stuff).

"A high production rate solves many ills"

No torch ignitors in the main chamber.

Edited by tater
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Posted (edited)
1 hour ago, tater said:

They want to get rid of the hydraulics and go straight electric for actuators.

Hmm, IIRC, Merlin could use the RP-1 fuel as hydraulic fluid. Somehow I don't think methane can be dual-purpose like that, so it makes sense to eliminate a separate fluid system. 

E: posted first, watched video later. Yup, that was covered. Methane is doable, but problematic due to low boiling point.

Edited by StrandedonEarth
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On 7/8/2022 at 6:20 PM, JoeSchmuckatelli said:

Is there a 'ground effect' for a rocket that would make a practice 'hoover' over water different from what they'd see at the pad?  

I would guess not. I understand that ground effect is due to increased pressure of air when close to a surface (because the air is more constrained).

Increased air pressure is good for wings, but not for rockets. 

Also, if ground effect did something, I would guess this would be mentioned when describing TWR, as arguably it is most important immediately on takeoff.

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56 minutes ago, mikegarrison said:

99% combustion efficiency is no big deal in a gas turbine. I'm not sure why Elon was so impressed by it.

Wiki indicates that 70-90% is good for a turbopump: https://en.wikipedia.org/wiki/Turbopump#:~:text=Turbopumps have a reputation for,this is a severe problem.

It looks like the efficiency problems are more with the fluid-handling side as opposed to the gas-turbine side(or at least all the listed issues seem to be related to fluid handling).

Also, the 99% includes not just two gas turbines, but also the two pumps, the combustion chamber and the rest of the engine.  Even if both turbines are at 99.9% that still means that the rest of the bits combined lose less than 0.9% total efficiency. 

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45 minutes ago, Terwin said:

Wiki indicates that 70-90% is good for a turbopump: https://en.wikipedia.org/wiki/Turbopump#:~:text=Turbopumps have a reputation for,this is a severe problem.

It looks like the efficiency problems are more with the fluid-handling side as opposed to the gas-turbine side(or at least all the listed issues seem to be related to fluid handling).

Also, the 99% includes not just two gas turbines, but also the two pumps, the combustion chamber and the rest of the engine.  Even if both turbines are at 99.9% that still means that the rest of the bits combined lose less than 0.9% total efficiency. 

No, you are talking about the pumping efficiency. He specifically said "combustion efficiency". At 14:30 or so.

Maybe rocket engines don't typically get the combustion efficiency of jet engines? I don't know, but 99% would be low for combustion efficiency in a jet engine.

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39 minutes ago, Terwin said:

Wiki indicates that 70-90% is good for a turbopump: https://en.wikipedia.org/wiki/Turbopump#:~:text=Turbopumps have a reputation for,this is a severe problem.

It looks like the efficiency problems are more with the fluid-handling side as opposed to the gas-turbine side(or at least all the listed issues seem to be related to fluid handling).

Also, the 99% includes not just two gas turbines, but also the two pumps, the combustion chamber and the rest of the engine.  Even if both turbines are at 99.9% that still means that the rest of the bits combined lose less than 0.9% total efficiency. 

Gas turbines burn gas or atomized liquid in air and even jet engines uses cooled turbine blades, the large ones in power plants don't bother about weight. 
Turbopumps, Well burning gas in pure oxygen is an nice way to cut steel while the engine is small even compared to an small fighter jet engine and no working gas to cool the blades. 
And yes outside the space shuttle, new Shepard, falcon 9 and Starship all turbo pumps are single use. 
I assume efficiency on cruise missile jet engines is well below 99% as they are small and single use. 

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