SpaceX News

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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kunkmiester
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Re: SpaceX News

Postby kunkmiester » Sat Jul 30, 2016 10:46 pm

Fun thing will be when the rockets start taking off, refueling while in space, then landing with enough to take off again, making the ground the stop off point, not space.
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Aero
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Re: SpaceX News

Postby Aero » Sun Jul 31, 2016 2:53 am

Aero

kunkmiester
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Re: SpaceX News

Postby kunkmiester » Sun Jul 31, 2016 3:43 am

The point would be to switch from terrestrial fuel to space based fuel. The trajectory wouldn't change much--you need just enough lag time for a tanker to meet and transfer the fuel load. If the rocket has enough gas to go up then back down, it should work. Problem I just thought of though is that they're using super chilled fuel to get things to where they have the load to make these maneuvers. While it would mean lifting off with a partial fuel load, it might not work well to leave it sitting around on the ground getting warm while reloading the rocket.
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Tom Ligon
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Re: SpaceX News

Postby Tom Ligon » Sun Jul 31, 2016 2:40 pm


kunkmiester
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Re: SpaceX News

Postby kunkmiester » Sun Jul 31, 2016 4:09 pm

The main thing I was seeing is you'd probably be saving a bit of fuel on lift-off, since you don't necessarily have a full rocket. You'd also have a price point savings, since the orbital fuel should be a bit cheaper to get despite transporting it to earth.

I've been wanting to see some math done on my rogue rocket ideas, though not sure how exactly to get that started.
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Re: SpaceX News

Postby paperburn1 » Tue Aug 02, 2016 1:30 am

It’s not, and never ever has been, about the cost of energy to get to orbit. Such arguments are flawed.
I am not a nuclear physicist, but play one on the internet.

kunkmiester
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Re: SpaceX News

Postby kunkmiester » Tue Aug 02, 2016 2:52 pm

It is, because ISP drives so much of the design process, but it isn't, because until now expendable launch vehicles have had fuel as a small fraction of their cost-- but it is now because the Falcon 9 reusable is shrinking the cost of the hardware per flight.

By the time things get to the point where my thought is feasible (it may not ever actually be done for any number of reasons) the cost of fuel will probably be one of the larger costs of a flight.
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Skipjack
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Re: SpaceX News

Postby Skipjack » Tue Aug 02, 2016 7:11 pm

According to Musk, the cost of the fuel in a first generation Falcon 9 was 200,000 USD. The newer F9 models are quiet a bit larger. Not sure exactly by how much volume has increased, but I would be confident saying that the cost of the fuel for an F9 launch is less than 500k USD.
Considering that a F9 launch (with a small enough payload for recovery) is currently about 62 million, the fuel (currently) makes less than 1% of the total launch cost. This relationship will probably start changing, once they start reusing their boosters more often. But there is a natural limit to how low the prices can go. With the current system, the booster makes about 3 quarters of the cost of the whole vehicle. The upper stage is 1 quarter. Add costs for range, launch operations and some profit margin, they may be able to reduce the launch cost by 50% with the Falcon9. So the fuel will still make only 2% of the total launch cost.

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Re: SpaceX News

Postby paperburn1 » Tue Aug 02, 2016 11:29 pm

That would be great if that were to occur. But right now fuel costs are just a small fraction of the cost of a rocket even when you include the infrastructure necessary to super chill the fuel like the falcon nine rockets are using. The ideal solution to open up our solar system is paraphrasing as Tom L says"unless you're using nuclear rockets you're just playing around the space travel"
I am not a nuclear physicist, but play one on the internet.

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Re: SpaceX News

Postby Skipjack » Wed Aug 03, 2016 12:49 am


kunkmiester
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Re: SpaceX News

Postby kunkmiester » Wed Aug 03, 2016 3:50 am

Short of a breakthrough, even nuclear is dubious. None of the nuclear thermal designs (best ISP that has the thrust to actually lift off) right now have the ISP and thrust/weight needed to break the payload issue you're only doubling chemical's already low payload fraction, at least as I understand the math. Nuclear also gets into fallout issues--you can do plenty if you accept a certain amount of nuclear pollution, but if you want a clean rocket, it's not much better than chemical.
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Skipjack
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Re: SpaceX News

Postby Skipjack » Wed Aug 03, 2016 5:20 am


ladajo
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Re: SpaceX News

Postby ladajo » Wed Aug 03, 2016 5:37 pm

I was looking at the launch schedules and it looks like SpaceX has rolled a bunch of stuff to the right. Maybe less busy for the rest of the year than I thought before.
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Re: SpaceX News

Postby paperburn1 » Thu Aug 04, 2016 10:32 pm

Looks like they have made changes to accelerate the falcon heavy schedule . :D
that's why they reserved the three pads for next month....
I am not a nuclear physicist, but play one on the internet.

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Re: SpaceX News

Postby Diogenes » Wed Aug 10, 2016 7:21 pm

‘What all the wise men promised has not happened, and what all the damned fools said would happen has come to pass.’
— Lord Melbourne —


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