Space X to build reusable launch vehicle

GIThruster · Post by **GIThruster** » Tue Oct 18, 2011 3:44 am

Skipjack wrote:. . .NASA hated the DC-X (because of its success with little money) and they also had the weird concept that choosing the most ambitious design was a good idea for some reason.
So they chose the Lockheed design. The cancellation was also dubious. One main reason cited was the failure of the cryogenic composite tank and the issues with it. Interestingly enough they built a replacement from aluminium which was much lighter and worked fine, but NASA rejected it anyway on the grounds that they wanted the composite tank research as part of the project. Instead of keeping it going with the aluminum tank, they threw out the entire project including the many things that worked.
Typical NASA management and politics crap and the reason why nothing has ever happened at NASA in over 30 years.
Sure, Lockmart was not without fault in all this, but NASA is just as much to blame.

Actually the situation was a bit more involved than that. X-33 was doomed from the start as result of failed systems engineering on the part of NASA. They gave the composite tank issue to a group with no composites experience, and the original systems design team designed a tank shape that could not be made without heavy seams. Only had the tank been seamless or nearly so, could it have come in on weight and it wasn't close.

Second problem was the aerospike. The engine team simply stated they needed an enormous copper heat sink and threw the problem at systems. Had systems not had their head up their ass, they would have scrapped the spike at that time and gone with SSME's. Problem solved. Instead, the lack of leadership left 2, horrible problems running at once. Then the first composite tank delaminated so it was not only over weight, but broken. The LiAl tank was known to be too expensive to put into service from before it was built. It was only built because someone broke the chain of command and ordered it so--and built a tank that is too expensive to use in commercial spacecraft--useless. Of course no one got fired, as they would if they were spending other than taxpayer money.

The problems were not L-M's. They were all incompetent management on the part of NASA. Had NASA brought Scaled Composites in for a consult early on, they would have known they needed a composite tank structure with no concave surfaces and X-33 might well have succeeded. DC-X and Roton really did not have near so good a chance to succeed. Both suffer the problem that the pilot cannot steer because he cannot see where he's going. During reentry, plasma stops mission control from piloting, so this turns out to be an extremely difficult issue that there was never found an answer to.

GIThruster · Post by **GIThruster** » Tue Oct 18, 2011 3:45 am

[edit for double post]

kunkmiester · Post by **kunkmiester** » Tue Oct 18, 2011 3:52 am

Much better to wait for a bigger and cheaper launcher, and also a business plan to make some money from going to the Moon.

You read my posts on here, Charlie? I've got a plan, I just have no business experience, connections, or money.

I doubt asking a billion for half a dozen five to seven man trips to the moon with my current resume would get more than laughs, but I think a base by 2020 could be feasible if SpaceX gets Dragon manrated and can get me the rockets.

GIThruster · Post by **GIThruster** » Tue Oct 18, 2011 4:12 am

IIRC, Dragon is not capable of going to the Moon. It has higher performance than Orion specifically because it was optimized for LEO and lacks the radiation protection needed for lunar missions. I'm sure Musk would remedy this provided a market, but in any case I think it unlikely it could fly more than 4 people to the Moon. Certainly, it cannot do that from a single Falcon 9. You'd need 3-4 launches minimum, to get 4 people round trip to the Moon and back--would certainly effect your business plans. I'd say you're looking at $50 million/seat, minimum.

Skipjack · Post by **Skipjack** » Tue Oct 18, 2011 5:11 am

DC-X and Roton really did not have near so good a chance to succeed. Both suffer the problem that the pilot cannot steer because he cannot see where he's going. During reentry, plasma stops mission control from piloting, so this turns out to be an extremely difficult issue that there was never found an answer to.

Remote control? Worked for the DC-X, worked for the Buran.
Cameras?
There were never any windows planned in the Venture Star, btw and it was meant to be unpiloted (but with a crew module).
The rest about management at NASA being insane is certainly true.
What is also certainly true is that NASA chose the most ambitious design. The design by Boeing e.g. was basically a larger X37b and that one is working pretty well as we all know (also is remote controlled).
I still think that the DC- X was the best approach though. Wings suck in space

Either way, the Lockheed design was the dumbest of them all.

IIRC, Dragon is not capable of going to the Moon.

Actually it is and tere are plans for a lunar orbiting mission using the Dragon.

It has higher performance than Orion specifically because it was optimized for LEO

No it isnt. E.g. the heatshield is designed to withstand a lunar return, even a return from mars. Elon Musk wants to go to mars and that is his declared goal. The Dragon capsule is part of the plan.

I think it unlikely it could fly more than 4 people to the Moon. Certainly, it cannot do that from a single Falcon 9.

I think that this is actually correct. They would need at least one Falcon Heavy launch for that. I think it is more actually, I am tired and dont want to look it up right now. There is a study about it too somewhere.
Musk wants to build a reusable lunar transfer infrastructure though, which requires even more than a one time stunt moon mission.
This is why he needs to lower the launch costs and that is why he needs reusability.

charliem · Post by **charliem** » Tue Oct 18, 2011 5:16 pm

kunkmiester wrote:
Much better to wait for a bigger and cheaper launcher, and also a business plan to make some money from going to the Moon.
You read my posts on here, Charlie? I've got a plan, I just have no business experience, connections, or money. I doubt asking a billion for half a dozen five to seven man trips to the moon with my current resume would get more than laughs, but I think a base by 2020 could be feasible if SpaceX gets Dragon manrated and can get me the rockets.

Sorry, Kunkmiester, I did not see it.

Can you give a link to the details, or tell me where to find them?

kunkmiester · Post by **kunkmiester** » Wed Oct 19, 2011 12:29 am

THought it was on here, it's actually here:
viewtopic.php?p=70396#70396

I want to put more than three people up at a time, so a transfer "stage" is necessary, I think. Ultimately, it'd be nice to have a Falcon Heavy for the LTV and lander, and a Dragon Cargo for each mission--five to seven people, two crew, and fuel and supplies.

The LTV could serve other purposes too, since it's basically a mannable habitat with a rocket attached.

A big advantage is that this frees up space on the Dragon--Since all you're carrying with you is the fuel for your delta V, the other weight can be put to other uses, such as building the supplies for a base.

Ray · Post by **Ray** » Wed Oct 19, 2011 2:15 am

Don't forget to include the possibility of a propellant depot in orbit. No need to send everything up in one launch. I don't take all the fuel I need with me, when I go touring in my car.

kunkmiester · Post by **kunkmiester** » Wed Oct 19, 2011 2:42 am

That would be an eventual goal, but I'm thinking that logistics would be a big limit right now--minimize the number of launches.

A tanker would probably have a super sized upper stage, and be dedicated to the role. It goes up, meets the depot or a tug on a low trajectory, transfers the fuel, then goes back down. That's presuming of course you don't plan to get fuel from the moon, which would happen eventually.

Skipjack · Post by **Skipjack** » Wed Oct 19, 2011 12:46 pm

I would make the LTV use nuclear engines (NERVA) and thus make it reusable for many, many, many flights. Just "fill er up" with some hydrogen and off you go!

charliem · Post by **charliem** » Wed Oct 19, 2011 3:22 pm

Skipjack wrote:I would make the LTV use nuclear engines (NERVA) and thus make it reusable for many, many, many flights. Just "fill er up" with some hydrogen and off you go!

I think that'd be great. Nerva engines, having more than two times the Isp of chemicals, could increase the mass fraction, LEO to LLO, from todays 25-30% to 60-65%, more then doubling it.

That would raise the fraction mass from Earth to the Moon above 1% (instead of prior <0,5%).

But I think that using them in the short term is quite unlikely. I'm sure that taking the necessary amount of fissionables (tonnes?) to orbit would find strong opposition, fueled by popular fears of anything nuclear. Who knows, it could become just a question of PR: take those ugly, dangerous, dirty, nuclear fuels away from the Earth, how can that not be something good? ...

But if we are talking long term I think that Electrical/Plasma thrusters are even more promising, at least for cargo. They are slow, but their Isp is even better than chemical, or even fission, engines (Hall thrusters can, theoretically, reach 8000s). I have not found any economic study comparison but intuition says that they have to be proportionally cheaper.

Although all that doesn't matter in the short term, we are bound to chemical engines by now.

Kunkmiester, it looks that your idea is similar to the one mentioned in this study by NASA that Skipjack mentioned a few posts ago: http://images.spaceref.com/news/2011/HATDepot.Study.pdf

But this study does not give any economic reason for going back to the Moon, just how to do it the cheapest way.

Skipjack · Post by **Skipjack** » Wed Oct 19, 2011 4:22 pm

I think that'd be great. Nerva engines, having more than two times the Isp of chemicals, could increase the mass fraction, LEO to LLO, from todays 25-30% to 60-65%, more then doubling it.

I am also thinking about the long term use of the vehicle. A nuclear reactor could operate it for decades. It would be a monopropellant, which should make logistics easier.

But I think that using them in the short term is quite unlikely. I'm sure that taking the necessary amount of fissionables (tonnes?) to orbit would find strong opposition, fueled by popular fears of anything nuclear.

Good point!
I think that if a private company does it, the public has not much to say about it. Launch it from Kwaijlen if you cant get a launch permit anywhere else.
There have been quite a few nuclear powered missions in the past decades, so it is not THAT unusual.
Sure a NERVA reactor would be bigger, but you could just pack it in a robust container and it should be save.

Maybe, one could also launch it in smaller quantities on secondary payloads and then assemble the thing in orbit.

But if we are talking long term I think that Electrical/Plasma thrusters are even more promising, at least for cargo. They are slow, but their Isp is even better than chemical, or even fission, engines (Hall thrusters can, theoretically, reach 8000s). I have not found any economic study comparison but intuition says that they have to be proportionally cheaper.

Their thrust is to low for transporting humans to the moon. It would take weeks to get there, but for cargo that would definitely be the better choice.

ELF thrusters like the ones developed by John Slough at MSNW could be a bit better though. One will have to keep an eye on the developments there. Slough recently got some funding from NASA to further develop his system.
Even better would be if someone would come and give him some funding for his fusion engine and fusion plasmoid space propulsion:
http://nextbigfuture.com/2010/12/fusion ... lsion.html

That could change the game completely, includig for getting to LEO, I believe.
If I was Musk or Bezos, I would finance those two things. It could really change life as we know it on several levels.

Skipjack · Post by **Skipjack** » Wed Oct 19, 2011 4:36 pm

This kinda fits the topic of a sustainable lunar architecture:
http://yfrog.com/kjq2sxfj

You would absolutely need fuel depots for that. You cant deliver this to the moon with the SLS either. You would need multiple SLS flights and then you might just as well do fuel depots and have them for all sorts of things.

charliem · Post by **charliem** » Wed Oct 19, 2011 8:40 pm

Skipjack wrote:
charliem wrote:But if we are talking long term I think that Electrical/Plasma thrusters are even more promising, at least for cargo. They are slow, but their Isp is even better than chemical, or even fission, engines (Hall thrusters can, theoretically, reach 8000s). I have not found any economic study comparison but intuition says that they have to be proportionally cheaper.
Their thrust is to low for transporting humans to the moon. It would take weeks to get there, but for cargo that would definitely be the better choice.

More like weeks-months.

My present favorite design in that category are the Ad Astra Company VASIMR thrusters. They are about to be tested in the ISS.

The VF-200 that they are going to fit the ISS with weights 300 kg (not much less than a Merlin 1C), needs 200 kW of electricity to operate, gives a max thrust of 5 N (at 3000 s of Isp), and has maximum Isp of 5000 s (with less thrust). Weak, I know, but you can use a bunch of them if necessary (although obtaining that much energy from solar panels can be a pain, much better a nuclear reactor).

In any case it'd be adequate for small payloads. An example: Lets say that we depart from LEO with a vehicle of 10 t total mass. Using the maximum thrust of 5 N (Isp=3,000s) the mass fraction to reach LLO is 87%, so 1.3 t of fuel (Argon) would be spent en route. Travel time about 3 months.

Summing up: From those 10 t, 1.3 would be fuel, 0.3 the engine, don't know how much for the 200 kW solar panel, 1 t?, and lets say 1 t for avionics and other hardware. So the cargo delivered would be 6.4 t

If that number does not sound impressive enough, multiply it for 10, from 100 t at LEO 64 t of cargo gets to LLO in 3 months.

There's no other present day technology that efficient, not even with NERVA engines.

And its advantages are even more evident if we travel farther.

If the goal where Mars I would send most of the cargo to low Mars orbit (delta-v 6100 m/s) using these engines, and then the crew in a faster vehicle with just enough of everything for the voyage. That cargo would be there in 4 months using the maximum thrust (just considering acceleration time), or 8 months using the most efficient Isp, in both cases with mass fractions well above 80% (minus ship hardware).

Skipjack · Post by **Skipjack** » Wed Oct 19, 2011 9:22 pm

Yeah, as I said, for cargo it makes sense, for humans not so much.
I wonder how an ELF thruster would do in comparison.