Virgin Galactic's VSS Enterprise's First Manned Glide Flight

[MKSheppard]

You seem to only think in terms of raw thrust... there are many other things that might be more important for a given task.

Raw thrust in the first stage enables heavier upper stages, and thus heavier payloads into orbit; it also enables greater reliability via lesser enginespam.

Take a look at the SpaceX Falcon 9 Heavy proposed design.

27(!!!) Merlin 1D Engines to put 32,000 lbs into LEO.

Now; the Defense Department took a look at that and began laughing so hard they couldn't stop; and told SpaceX to stop fucking around with them regarding proposals for space launch services for the DoD.

It's why in a Powerpoint this August, they started to talk about a notational Falcon 9 Heavy Block II with just three "Merlin 2" engines.

Of course, these Merlin 2s are notationally 1.7 million lbf; a massive increase in thrust over Merlin 1.

And of course, on top of this, they're talking about developing a so called "Raptor" upper stage engine...which will of course be Liquid Hydrogen powered.

If you haven't started laughing, you will now.



Nevermind where they are going to get the funding for this from...as you've seen, it cost Rocketdyne $1.7 billion in FY91 dollars to develop the F-1. Adjusted to FY2009 prices, that's $2.64 billion.

Even if we presuppose SpaceX can develop a F-1 class engine for 45% of the cost of the F-1; that still comes out to $1.1 billion USD to develop it. Of course; SpaceX has claimed they can develop it for $1 billion (at the AIAA Joint Propulsion Conference 2010).

Where's SpaceX going to get that money for future development; continue to uprate it's rockets; develop new classes to take advantage of the new Merlin 2; AND develop a high-energy LH2 upper stage?

Have there been manned missions to the moon lately? Then why should NASA have build more Saturns V?

Because a Saturn V Class vehicle is awesome for unmanned missions.



Figure is from "Launch Vehicle Performance Capability" in "Mid-Term Technical Progress Report Advanced Planetary Probe Study" circa 15 March 1966 by TRW.

--------------------------------

Saturn V/Centaur injection capabilities:

200 km2/s2 and 10,100 lbs
150 km2/s2 and 15,900~ lbs
100 km2/s2 and 26,800~ lbs
70 km2/s2 and 37,500~ lbs

--------------------

Saturn V (bare) injection capabilities:

169 km2/s2 and 1,900 lbs (Maximum Possible)
150 km2/s2 and 4,900 lbs
100 km2/s2 and 17,300 lbs
70 km2/s2 and 29,800 lbs

---------------------

To put this into context; the NEW HORIZONS mission to Pluto-Charon that was launched a bit ago for a flyby of Pluto required 149 km2/s2 of C3. LINK

New Horizons weighed 1,050 lbs because it had to be launched by an Atlas V 551.

If we still had a Saturn V production line open; then NEW HORIZONS could have weighed 4,900 lbs. If we had added CENTAUR capability to the Saturn V; we could send a 15,900 lb NEW HORIZONS to Pluto.

Either that, or we could have NEW HORIZONS arrive in something less than nine years (launch was 2006, arrival is 2015).

And while we are at it: the SSME is a far superior engine, its also still in active use.

You mean the engine that can only produce 400,000 lbf of thrust at sea level, requiring more of them to be clustered together, operates at 2,700 PSI, and costs $50 million?

I fucking laugh at the DIRECT people who seem to think that throwing away a $50 million dollar engine after each flight is a good idea.

But thanks for proving that SpaceX is better/more competent now than Rocketdyne was forty years ago...

Right. Because producing an engine that only produces 125,000 lbf is as technically difficult as producing one that produces 1.8 million lbf at sea level.

:rolleyes:

[MKSheppard]

Wouldn't it be cheaper just to buy RD171 engine for heavy lift rocket than develop the F1A. RD171 is already in production so no need to pay R&D costs and build new assembly line. It is more powerful and far more efficient than F! was, probably as efficient as realistically possible for practical LOX/Kerosene engine. RD171 also has to be fairly cheap since Zenit is among the cheapest rockets when it comes to $/kg.

RD-171 produced 1.7 million lbf for a engine weight of 20,900 lbs in four clustered combustion chambers. Each chamber ran at about 3,553 PSI.

F-1A produced 1.8 million lbf for an engine weight of 17,853 lbs in a single combustion chamber at 1,015 PSI.

Here's a hint; the lower the PSI on your combustion chamber, the more reliable your engine is -- there's a reason the RS-68 went from the SSME's 2,747 PSI to a much more modest 1,392 PSI.

Plus....your engine can be made a hell of a lot cheaper the lower the chamber pressure.

[Geodd]

RD-171 produced 1.7 million lbf for a engine weight of 20,900 lbs in four clustered combustion chambers. Each chamber ran at about 3,553 PSI.

Yeah, the Russians never quite got a handle on the problems with combustion instability associated with very large combustion chambers.

But to be fair, with the computer simulation capability around these days designing a big engine ought to be cheaper. Learning mainly by trial and error(or boom!in this case) is, as you've noted earlier in this thread, very expensive.

[Simon_Jester]

That said, it's still going to be a painfully expensive process, and I have to agree with Shep (ouch!): I'm skeptical of companies that are still ambitiously charging into the business building castles in the air that are held up entirely by their ability to pull it off.

[MKSheppard]

More to the point.

In 1992 immediately after the USSR's collapse; the Energia system was still in a position to be restored to production -- it last flew in 1988; so where the fuck was the FREE MARKET buying interest in NPO Energia?

Or in 2001, when the X-33 program was cancelled? All because of a dumb idiot who testified to Congress that if X-33 could not fly with a composite tank, it was not worth flying...

...never mind that Engineers had already made a LIGHTER aluminum-lithium tank at that point.

So where was the FREE MARKET stepping in to continue the X-33 research?

Fucking god-damned libertopians.

[Geodd]

In 1992 immediately after the USSR's collapse; the Energia system was still in a position to be restored to production -- it last flew in 1988; so where the fuck was the FREE MARKET buying interest in NPO Energia?

Well the oligarchs basically in charge at the time were a bit busy with coke, whores and massive defraudment of the so called "government" to really capitalize on that opportunity.

Or in 2001, when the X-33 program was canceled? All because of a dumb idiot who testified to Congress that if X-33 could not fly with a composite tank, it was not worth flying...

Well, to be fair the X-33 and even more so the planned VentureStar had a few more more issues than that. But considering how a lot of military projects are handled, the reason for canceling it :"Holy shit, it has some problems and is slightly over budget" is kinda hilarious. Almost makes me believe that the military should handle it, and hide it in some deep dark recesses of their budget. And as a card carrying pacifist - that just hurts me deep inside.

As for some of the current in-vogue private efforts, SpaceX is basically re-inventing the wheel, on the cheap, in a borderline saturated market. Seems smart to me... I'll be somewhat impressed/surprised if they manage to get decent reliability out of the Falcon 9 and kinda horrified if they con someone into man-rating the thing. If they somehow manage to finance that FalconX thing they're talking about - good for them, it might even be useful.

Now Burt Rutan and Virgin Galactic, well SS2 is a toy, but at least they admit it. And if they get enough cash to build SS3 things get interesting. Point-to-point suborbital spaceflight actually has uses.

[MKSheppard]

SpaceX talks a lot of smack about them being the first; but they're full of it as usual:

Link to Conestoga

I won't reprint the article here; but they became the first privately funded rocket to reach space in 1982.

Yet.....nothing happened; despite them being in business until about 1995 -- and having a virtual guranteed market following Challenger; and all those payloads which had to now find a new launch vehicle.

Or how about OTRAG?

OTRAG was a Germaninoid attempt in 1975-1981 to produce a cheap low cost rocket by a Germanoid engineer named Lutz Kayser.

The idea was to use shitloads of clustered pressure fed propulsion moduels to place payloads into orbit.

And it attracted some nice luminaries; Kurt Debus (First director of KSC) and Wehrner Von Braun (duh) as chairman of the board and scientific advisor.

Of course; OTRAG went nowhere.

[Simon_Jester]

Or how about OTRAG?
OTRAG was a Germaninoid attempt in 1975-1981 to produce a cheap low cost rocket by a Germanoid engineer named Lutz Kayser.
The idea was to use shitloads of clustered pressure fed propulsion moduels to place payloads into orbit.
And it attracted some nice luminaries; Kurt Debus (First director of KSC) and Wehrner Von Braun (duh) as chairman of the board and scientific advisor.
Of course; OTRAG went nowhere.

OTRAG seems to have run into problems as much on account of being a German missile company as anything else. Cold War politics made for problems, as did having to test the rockets in Qaddafist Libya (guess how that turned out). While those are inherent problems with private rocket development, they're not exactly ones someone like SpaceX or Burt Rutan has to deal with.

[Skgoa]

The United Launch Alliance is already using Russian made RD180 which is a scaled down version of RD171. IIRC there were even some talk about licensing the RD180 production in US. I don't see a reason why similar agreement couldn't be made regarding RD171 if the US want to preserve skills and workforce needed to make large rocket engines. Russians have the best LOX/Kerosene engines in the world so it would make sense to use thair experince and not to try to reinvent the wheel. NASA could save billions of R&D costs if it decided to use already existing RD171 for planned heavy lift rocket.

The valuable skillsets are not limited to production, R&D is a very very important set of skills and this tends to go away very very fast. (E.g. people simply getting other jobs...) Its crucial for anyone who wants to be a big player in space to design and build his own rockets.

Even more R&D money could be saved if it was decided to revive Energia rocket. Zenit boosters are still in production as first stage for Zenit rocket. There are few dozens of RD 0129 engines still in storage, those could be used until production is restarted. Energia core stage and shuttle external tank have similar dimesions so it might be possible to use same factory that builds external tanks to build Energia core stages.

I doubt that will happen, ever.

Any space exploreration program that recquire serious heavy lift capability are likely to be international undertaking like ISS so I don't see anything wrong with using an internationally built rocket.

Neither do I, but as I aluded above, americans have a problem with that, since they want to keep their leading position...

There are some interesting developements regarding restartable/"dual use" engines. We might see "stages" that are just different operational modes instead of physical parts of the rocket breaking of, in the future.

Do you mean the SABRE engine which would use atmosferic air to burn fuel at low altitudes and switch to onboard LOX supply when air becomes too thin?

No, I was refering to "conventional" engines that e.g. burn kerosene at first and then switch to hydrogen. And I am not convinced about the abilites of SABRE, to be honest.

[Sky Captain]

Wouldn't it be cheaper just to buy RD171 engine for heavy lift rocket than develop the F1A. RD171 is already in production so no need to pay R&D costs and build new assembly line. It is more powerful and far more efficient than F! was, probably as efficient as realistically possible for practical LOX/Kerosene engine. RD171 also has to be fairly cheap since Zenit is among the cheapest rockets when it comes to $/kg.

RD-171 produced 1.7 million lbf for a engine weight of 20,900 lbs in four clustered combustion chambers. Each chamber ran at about 3,553 PSI.

F-1A produced 1.8 million lbf for an engine weight of 17,853 lbs in a single combustion chamber at 1,015 PSI.

Here's a hint; the lower the PSI on your combustion chamber, the more reliable your engine is -- there's a reason the RS-68 went from the SSME's 2,747 PSI to a much more modest 1,392 PSI.

Plus....your engine can be made a hell of a lot cheaper the lower the chamber pressure.

Howewer lower chamber pressure means you loose ISP although that might be partially offset by higher thrust to weight ratio of F1A. Speaking of costs RD171 has to be relatively cheap considering the launch price for whole Zenit rocket is 35 - 50 million $ - cheaper than single SSME. United Launch Alliance buy RD180 for 10 million. How Russians have managed to make RD180 and RD171 that cheap despite the high performance I don't know. Regarding reliability only Zenit failure caused by RD171 malfunction was caused by debris sucked into turbopumb, but that would destroyed any other pump fed engine too.