Background on the Falcon 9 Launch
spacex.com
Background on the Falcon 9 Launch
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Re: Background on the Falcon 9 Launch
#2"[100Km altitude] is the equivalent of the starting line of a race. The race itself is the kinetic energy."
Did you get that, Jeff?
The truth is, they have both achieved an astonishing amount.
Re: Background on the Falcon 9 Launch
#3One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base?
I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
Re: Background on the Falcon 9 Launch
#4One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base? I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
You're right not to trust your intuition! Good call.
It's actually going to be much, much less than that due to the nature of the rocket equation. https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation
Re: Background on the Falcon 9 Launch
#5One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base? I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
About 30% returning to landing site, 15% returning to a barge downrange. Note that the rocket's still perfectly capable of running an expendable mission if the payload requires it. The mass figure on their website[1] is for reusable.
Re: Background on the Falcon 9 Launch
#6One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base? I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
I don't think you could allocate all of the landing fuel load to payload as any addition to the payload also requires additional 2nd. stage fuel.
Re: Background on the Falcon 9 Launch
#7"[100Km altitude] is the equivalent of the starting line of a race. The race itself is the kinetic energy." Did you get that, Jeff? The truth is, they have both achieved an astonishing amount.
Comparing apples (going up then down) to oranges (getting into orbit). Pretty awesome to see these guys putting their cash towards this! Hope a rivalry heats up and I can goto Mars for $3.50.
Re: Background on the Falcon 9 Launch
#8One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base? I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
I don't think you could allocate all of the landing fuel load to payload as any addition to the payload also requires additional 2nd. stage fuel.
You can run the first stage longer without any extra second stage fuel. Adding performance to either one (within limits) increases the performance of the system. Using the landing fuel for a launch would allow for a heavier payload without changing the second stage. The first stage would do more of the total work.
Re: Background on the Falcon 9 Launch
#9My favorite way to describe orbits is 'constantly throwing yourself at the ground but moving so fast that you just keep missing', hence the constant free-fall/zero-g.
Re: Background on the Falcon 9 Launch
#10One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base? I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
According to http://aviationweek.com/blog/nasa-cnes-warn-spacex-challenge... every 10lbs of recovery hardware loses you 1lb of payload, approximately.