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SpaceX Grasshopper Flies High

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Re: SpaceX Grasshopper Flies High

#41

Post by artursapek »

petenixey wrote: post #35
EthanHeilman wrote: post #30

Earlier quoted context omitted.

Fuel is very inexpensive (~2% the cost of a rocket launch), rockets are very expensive. If you can trade off fuel for not having to build a new rocket you drop the cost to orbit by orders of magnitude. Additionally you can build more expensive rockets that are more efficient since rocket creation becomes a capital rather than a reoccurring cost.

But why not just use a parachute and airbags? They're going to be a vast amount lighter than the fuel you'd need for a rocket landing.

I don't think a parachute would give them the amount of control they want over where it lands. Maybe the idea is to eventually have many of these things docking in the same area, like an airport. If you have a fleet of multi-million dollar rockets, you want to be in as much control of them as possible.

Re: SpaceX Grasshopper Flies High

#42

Post by EthanHeilman »

petenixey wrote: post #35
EthanHeilman wrote: post #30

Earlier quoted context omitted.

Fuel is very inexpensive (~2% the cost of a rocket launch), rockets are very expensive. If you can trade off fuel for not having to build a new rocket you drop the cost to orbit by orders of magnitude. Additionally you can build more expensive rockets that are more efficient since rocket creation becomes a capital rather than a reoccurring cost.

But why not just use a parachute and airbags? They're going to be a vast amount lighter than the fuel you'd need for a rocket landing.

You can't direct where the rocket ends up, highly likely that the rocket will get damaged or much less likely that the rocket will damage something else (This is why NASA dumps it's rockets over the ocean). Then you have find a way to get the rocket home, which involves time and money. Why not just burn fuel (rocket fuel is only a few times more expensive that burning water) and bring the rocket home?

If you need more payload build a bigger rocket.

You could also add wings to the rocket and fly it home which has it's own set of trade-offs and benefits(see space shuttle).

Re: SpaceX Grasshopper Flies High

#43

Post by smackfu »

DigitalJack wrote: post #3

Haven't heard much from Armadillo Aerospace in a while. Are they still active?

They've always seemed more like a hobby company than the competitors. Their small scale has really seemed to slow them down, like lots of manufacturing and sourcing issues that a bigger company can just throw money at.

Re: SpaceX Grasshopper Flies High

#44

Post by jerf »

rplnt wrote: post #12
StylifyYourBlog wrote: post #2

Its likely that full-fledged Space Travel with reusable rockets will be possible in the coming years

I believe same thing was done by NASA in the 70s. So not really big step forward in this particular regard. edit: Can't find it at the moment. So far I've found http://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X which did what grasshopper and more almost 20 years back. I still believe I've read something earlier though. Will edit when/if I find it.

No. It was a stated goal of the Space Shuttle project, but it failed. Had the Space Shuttle been a commercial venture it would have been abandoned decades ago; other than the fact that it generally worked (which, to be clear, is saying something, that's not guaranteed), it was an awful design.

Re: SpaceX Grasshopper Flies High

#46

Post by InclinedPlane »

marvin wrote: post #14
InclinedPlane wrote: post #6

Earlier quoted context omitted.

The pace of progress seems to have been faster than even SpaceX anticipated. Within the next year we'll see very significant tests of core components of the system and flight profile (for the first stage at least). The very next Falcon 9 flight (out of Vandenberg) will use the performance overhead provided by the v1.1 upgrade to do a controlled reentry of the 1st stage and then after it has reached terminal velocity…

Do you have more information on the "water landing" planned for the next Falcon 9 flight? Why won't the SpaceX team attempt to land it on some sort of floating platform? Seems to me that this would yield an even better test "for free" and even provide the possibility of recovering the first stage for analysis.

They'd have to add flight worthy landing gear, which hasn't been tested yet and would add weight. This test just uses a straight up stock Falcon 9 v1.1 first stage, so it's super low overhead. Also, they're not sure it'll work. But if it doesn't it just means they end up with what they were expecting, broken up first stage bits in the ocean.

They do plan on retrieving the stage if possible, it should float.

Re: SpaceX Grasshopper Flies High

#50

Post by ryanbrush »

stuff4ben wrote: post #37
deepblueocean wrote: post #25

Earlier quoted context omitted.

I find this confusing. It's awesome, that's for sure. But it seems like lifting all the fuel needed to do a soft landing is inherently a tradeoff for less payload capacity. What is the benefit, then? Is it just so much cheaper to be able to re-use the first two stages?

I thought the same thing. One of the Youtube commentswas pretty insightful in that it mentioned that when you do a parachute landing into the ocean, it's landing in salt water. Therefore the craft has to be taken apart inspected, cleaned, and put back together. So I'm assuming they've done the cost benefits and figured it's cheaper this way. I wonder if a combination parachute/thruster landing would be more feasible…

Not to mention the operational costs of a small navy to recover the rocket and transport it to a launch site.
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