Space X to build reusable launch vehicle

Skipjack · Post by **Skipjack** » Thu Sep 29, 2011 8:45 pm

Elon Musk speaking at National Press Club Luncheon - Sept. 29, 2011
http://www.hobbyspace.com/nucleus/index ... emid=32777
You definitely want to watch the video!
This is sooo cool!
http://www.youtube.com/watch?v=sSF81yjV ... r_embedded

Giorgio · Post by **Giorgio** » Thu Sep 29, 2011 9:24 pm

If they can do what they show in the video I will be really mesmerized...

Skipjack · Post by **Skipjack** » Thu Sep 29, 2011 9:50 pm

Elon Musk is betting quite some money on it. They will start testing of a suborbital prototype vehicle soon (already got the permits for that).

Giorgio · Post by **Giorgio** » Thu Sep 29, 2011 10:05 pm

Yes, I saw that, but we are talking about a 3 stage rocket with each stage having an independent return system.
This is more than a tough bet, it required a complete re-thinking of the idea of a what a rocket is and the way it is built.

If he is able to achieve that he will cut costs to space of an order of magnitude at least. It will be an amazing feat.

ladajo · Post by **ladajo** » Thu Sep 29, 2011 10:05 pm

I just do not see the fuel and thrust densities to support what he is doing. Not to mention the re-entry maneuvers. Braking, atmosphere, roll, friction braking, roll, braking, landing... that is a lot of stress.
So how does he plan to fit that much thrust into that size package? Effectively two launches worth of thrust in one launch package.

Giorgio · Post by **Giorgio** » Thu Sep 29, 2011 10:06 pm

Exactly.

DeltaV · Post by **DeltaV** » Thu Sep 29, 2011 10:40 pm

Every time I see SpaceX's plans for the future, one thought enters my mind: "These sumbitches are serious."

It's probably just reflexive amazement due to decades of NASA plodding.

KitemanSA · Post by **KitemanSA** » Fri Sep 30, 2011 4:13 am

The video shows a single core rocket, 2 stage plus payload module. Seems a bit of a reach as shown. But if they do something like a 9-Heavy with two fly back boosters around the core... what then?

I guess my second question would be, would the tail landing method seen in the video be lighter and cheaper than a scissor wing / skid horizontal landing system?

djolds1 · Post by **djolds1** » Fri Sep 30, 2011 5:36 am

ladajo wrote:I just do not see the fuel and thrust densities to support what he is doing. Not to mention the re-entry maneuvers. Braking, atmosphere, roll, friction braking, roll, braking, landing... that is a lot of stress.
So how does he plan to fit that much thrust into that size package? Effectively two launches worth of thrust in one launch package.

I'd bet 1.2 launches - probably uses atmo drag to bleed the first 6000m/s on reentry, and then propulsion for the last 2000m/s. Total dv 12,000m/s.

Or this is a disguised test for a Mars lander.

Skipjack · Post by **Skipjack** » Fri Sep 30, 2011 7:08 am

I'd bet 1.2 launches - probably uses atmo drag to bleed the first 6000m/s on reentry, and then propulsion for the last 2000m/s. Total dv 12,000m/s.

Yeah, that was my thought as well. I was actually even a bit more optimistic with 1.1 to 1.15. Though that guess was for the first stage only.

Dont forget that the stages are very bouyant when they are almost completely empty. So they dont need that much thermal protection and they should have a pretty good crossrange on their way down.
They made some really good experiences with the Pico TPS systems on Dragon. They realized that they went way overboard with it on the first capsule. That stuff is ablative, but it barely got burned on the surface during the reentry. I read a quote somewhere that they could probably reuse that heatshield almost 100 times at the rate of ablation. So if they were to plan on reusing the TPS only a couple of times instead of 100 times, then they could reduce the mass of that quite a bit. Those savings would apply to everything.
Then they will have more efficient engines soon, both first stage and second stage. From what I understand F9 still had some margins with the dragon capsule and they have additional margins for savety. So if they assume that they dont need them, or rather they accept the loss of a stage that failed somewhere and so used up those margins, they can probably get a few more percent out of that.
With the multistage design they leave themselves a lot of options there. They can just accept the loss of a stage during reentry if nothing goes perfectly as planned (e.g. an engine fails, or a the TPS is for some reason used up more than expected) and the crew and return cargo will still be save.
I do have to admit that I am really, really suprised by the second stage reuse. I think that this is going to be really hard. From all that I have seen so far, I guess that they are aiming for first stage reuse first and then move on to second stage reuse once they have mastered the first one. They do not have to reuse both right away and I think the first stage will already be challenging enough.

TDPerk · Post by **TDPerk** » Fri Sep 30, 2011 9:51 am

ladajo wrote:I just do not see the fuel and thrust densities to support what he is doing. Not to mention the re-entry maneuvers. Braking, atmosphere, roll, friction braking, roll, braking, landing... that is a lot of stress.
So how does he plan to fit that much thrust into that size package? Effectively two launches worth of thrust in one launch package.

Oh good Lord, no! Think about it.

It's one full launch and one empty launch. Like 1.1 or 1.05 launch's worth.

The issue is not whether it can be done, it's whether they can keep the payload fraction they need.

Giorgio · Post by **Giorgio** » Fri Sep 30, 2011 10:31 am

NBF has coverage of Elon Musk and the reusable Falcon9 with some additional info and data too:

http://nextbigfuture.com/2011/09/cspan- ... -talk.html
http://nextbigfuture.com/2011/09/pictur ... con-9.html

/-- Pivotal break-through is a fully reusable, rapid turnaround rocket
/-- 2-3% of expendable initial total mass gets to orbit
/-- Adding reusability cuts into that 2-3%
/-- Very tough engineering problem. Wasn't sure for awhile that it could be solved. In past year decided that it could be.
/-- SpaceX will try to do it. No guarantee of success.
/-- Calculations and simulations say it should work.
/-- See simulation (video below).
/-- Falcon 9 is the lowest cost rocket in world at ~$50M
/-- Fuel is only about $200,000
/-- So if could reuse it would lead to 100 times reduction in cost.
/-- Fully reusable rapid turnaround is absolutely required for practical spaceflight and making humanity multiplanetary.
/-- A little base is not interesting.

Skipjack · Post by **Skipjack** » Fri Sep 30, 2011 12:25 pm

Actually the coverage is a direct copy from HobbySpace (which I linked above)...

Giorgio · Post by **Giorgio** » Fri Sep 30, 2011 3:41 pm

True, I didn't notice that it was the same links..... sorry about that

ladajo · Post by **ladajo** » Fri Sep 30, 2011 3:42 pm

TDPerk wrote:
ladajo wrote:I just do not see the fuel and thrust densities to support what he is doing. Not to mention the re-entry maneuvers. Braking, atmosphere, roll, friction braking, roll, braking, landing... that is a lot of stress.
So how does he plan to fit that much thrust into that size package? Effectively two launches worth of thrust in one launch package.
Oh good Lord, no! Think about it.

It's one full launch and one empty launch. Like 1.1 or 1.05 launch's worth.

The issue is not whether it can be done, it's whether they can keep the payload fraction they need.

I agree, I spoke in haste. You guys are right. It would be interesting to see the actual curves for dV and thrust mass.