Stratolaunch: General Company and Development Updates and Discussions

[Lurker Steve]

of course those "wise men" were assuming a reusable launch vehicle with the development and recurring cost of the STS, an RLV built to keep the NASA centers occupied. They were not talking about any conceivable RLV. And since that is OT for this thread, I will leave it at that.

Wrong on all accounts, again.   Know who you are talking to. 

Well, I am sure that they did not assume a more expensive one, because then the 60 launches would not have covered the cost. With a cheaper vehicle with lower running cost, they would not need that many launches to make it cost effective. No?

I think the point is that to make the LV reusable, it becomes more expensive, since the components that the LV is made from have to be more durable in order to last multiple missions. that durability comes with the cost of more weight and less efficiency. You have to get lots of use out of that LV, just because it cost so much to initially develop and build.

Is that number really 50-60 launches per year, or just 50-60 launches per vehicle ?

[Proponent]

Well, wiser men than me concluded in 1975 that a reusable launch vehicle becomes more economical than an expendable one at the rate of 50 to 60 launches/year (reason: added development and recurring cost of the reusable, which has a much worse G/P than an expendable and more expensive components, which must be amortized through the life of the program at a time-discounetd rate).  That justified the Shuttle, which was planned to fly once a week (*cough*, *cough*...)

Even wiser men concluded in 2000 that the "crossover" annual rate between expendable and reusables, given the technology in 2000 was ... can you guess?... 50 to 60 launches per year!

And there is a RAND study from way back in 1966 according to which expendables would be cheaper than reusables for a program requiring 72 Mlb into LEO between 1970 and 1999.  That's an average of 2.4 Mlb per year, equivalent to 48 launches per year of a 50,000-lb-capable vehicle.  (I used to have an electronic copy of this study, but somehow I trashed it.)

[baldusi]

Yes, Russians calculated at 1,000 to 3,000tonnes per year to LEO. And you have the granularity issue.

[mrmandias]

These studies were for completely reusable vehicles, no?  So not directly relevant to a question about first stage reusability.

I still think a recoverable Stage One would be a nice move.

Yeah, I am a bit confused by that. They spend all that money on developing a huge carrier plane and then they launch an expendable rocket from it. I do understand the advantages of airlaunch, but still this just feels "wrong".

Well, wiser men than me concluded in 1975 that a reusable launch vehicle becomes more economical than an expendable one at the rate of 50 to 60 launches/year (reason: added development and recurring cost of the reusable, which has a much worse G/P than an expendable and more expensive components, which must be amortized through the life of the program at a time-discounetd rate).  That justified the Shuttle, which was planned to fly once a week (*cough*, *cough*...)

Even wiser men concluded in 2000 that the "crossover" annual rate between expendable and reusables, given the technology in 2000 was ... can you guess?... 50 to 60 launches per year!

No coincidence: specific impulse and structural mass fraction, the two key figures of merit that determine the expendable vs. reusable G/P (the main contributor to the "crossover" rate,) really haven't changed much since 1975.

BTW this result is to first order independent of the launch mode (ground or air.)

OK - since I'm atop the soap box, I'm going to pontificate and you guys can't stop me: 

Yesterday I gave a lecture to the docents at the Udvar-Hazy on Pegasus, since they have one on display (the "artifact", as museum curators say.)  I started the lecture trying to convince them how fundamentally different aircraft and rockets really are, a difference that many, many things try to blur (e.g. "Air and Space Museum", "NASA" and my degree in "Aeronautics and Astronautics".)  So I started the pitch with a picture of the Bruce Nuclear Generating Station (BNGS) in Bruce County, Ontario, the world's largest (operating) nuclear power plant.  BNGS's EIGHT reactors produce 14,000 MW of THERMAL power in order to generate 4,000 MW of electricity (about 30% efficiency.)

The two SRB's on the Shuttle consume 1,000,000 Kg of solid propellant (at 4 MJ/kg) in 120 seconds, thus generating 33,000 MW of thermal power during their burn - more than twice that of BNGS... and Saturn V's stage 1 numbers are even more impressive: 185,000 MW, the equivalent of 14 times the world's largest nuclear power plant!!!!!!!!

Anytime you are handling this amount of power it's going to be a) very dangerous and b) very expensive, especially if it has to be lightweight enough to fly!

Aircraft and rockets - they just aren't the same thing.

[Robotbeat]

These studies were for completely reusable vehicles, no?  So not directly relevant to a question about first stage reusability.

I still think a recoverable Stage One would be a nice move.

Yeah, I am a bit confused by that. They spend all that money on developing a huge carrier plane and then they launch an expendable rocket from it. I do understand the advantages of airlaunch, but still this just feels "wrong".

Well, wiser men than me concluded in 1975 that a reusable launch vehicle becomes more economical than an expendable one at the rate of 50 to 60 launches/year (reason: added development and recurring cost of the reusable, which has a much worse G/P than an expendable and more expensive components, which must be amortized through the life of the program at a time-discounetd rate).  That justified the Shuttle, which was planned to fly once a week (*cough*, *cough*...)

Even wiser men concluded in 2000 that the "crossover" annual rate between expendable and reusables, given the technology in 2000 was ... can you guess?... 50 to 60 launches per year!

No coincidence: specific impulse and structural mass fraction, the two key figures of merit that determine the expendable vs. reusable G/P (the main contributor to the "crossover" rate,) really haven't changed much since 1975.

BTW this result is to first order independent of the launch mode (ground or air.)

OK - since I'm atop the soap box, I'm going to pontificate and you guys can't stop me: 

Yesterday I gave a lecture to the docents at the Udvar-Hazy on Pegasus, since they have one on display (the "artifact", as museum curators say.)  I started the lecture trying to convince them how fundamentally different aircraft and rockets really are, a difference that many, many things try to blur (e.g. "Air and Space Museum", "NASA" and my degree in "Aeronautics and Astronautics".)  So I started the pitch with a picture of the Bruce Nuclear Generating Station (BNGS) in Bruce County, Ontario, the world's largest (operating) nuclear power plant.  BNGS's EIGHT reactors produce 14,000 MW of THERMAL power in order to generate 4,000 MW of electricity (about 30% efficiency.)

The two SRB's on the Shuttle consume 1,000,000 Kg of solid propellant (at 4 MJ/kg) in 120 seconds, thus generating 33,000 MW of thermal power during their burn - more than twice that of BNGS... and Saturn V's stage 1 numbers are even more impressive: 185,000 MW, the equivalent of 14 times the world's largest nuclear power plant!!!!!!!!

Anytime you are handling this amount of power it's going to be a) very dangerous and b) very expensive, especially if it has to be lightweight enough to fly!

Aircraft and rockets - they just aren't the same thing.

Yes, and after all, you /could/ consider Stratolaunch (or Stargazer) as the first stage of the rocket. Clearly you don't need 50-60 launches a year to make that worthwhile, do you?

[Elmar Moelzer]

I would really like to see the actual calculation (with baseline cost estimates) for the 50 to 60 launches per year. And I believe the RAND study assumed Saturn size payloads (at lest from the small excerpt, the rest is behind a paywall)...

[lereyna]

One crazy idea, add a couple of spaceshipone/two-like feathers to the air launched first stage being designed by Orbital and bring it back as a reusuble first stage. I'm not an engineer so don't know the technical feasibility of such an aproach. I'd like to know your views on this idea. Also I don't know if there are any intelectual property issues that would prevent them from using this aproach, if it was feasible.

I'd really like your feedback on this.

LR

[QuantumG]

Welcome to the forum!

I think such a stage would have to glide forward, which adds cost to the recovery efforts that you have to account for. It could still be a winner, but any recovery mass added eats into the payload to orbit and that's very limited already.

[RanulfC]

I still think a recoverable Stage One would be a nice move.

Yeah, I am a bit confused by that. They spend all that money on developing a huge carrier plane and then they launch an expendable rocket from it. I do understand the advantages of airlaunch, but still this just feels "wrong".

Well, wiser men than me concluded in 1975 that a reusable launch vehicle becomes more economical than an expendable one at the rate of 50 to 60 launches/year (reason: added development and recurring cost of the reusable, which has a much worse G/P than an expendable and more expensive components, which must be amortized through the life of the program at a time-discounetd rate).  That justified the Shuttle, which was planned to fly once a week (*cough*, *cough*...)

Even wiser men concluded in 2000 that the "crossover" annual rate between expendable and reusables, given the technology in 2000 was ... can you guess?... 50 to 60 launches per year!

No coincidence: specific impulse and structural mass fraction, the two key figures of merit that determine the expendable vs. reusable G/P (the main contributor to the "crossover" rate,) really haven't changed much since 1975.

Not to "disagree" with "wiser-men" mind you, (which is exactly what I'm going to do anyway ) the major "issue" I've always had with ther wisdom is it tends to be VERY attached to the "standards-and-assumptions" made initially.

As an example I'll reference here:
http://forum.nasaspaceflight.com/index.php?topic=31025.msg1009428#msg1009428
Specifically:
"On the contrary, 40 a year is the general rule-of-thumb for a totally reusable launch vehicle (first and second stage). Work by Lockheed suggested that first-stage reuse is viable starting around just 6-8 flights per year."

Which it seems Blue Origin "believes" to be a correct assesment given:
http://forum.nasaspaceflight.com/index.php?topic=10685.msg1018777#msg1018777
"Blue Origin said it plans about 12 orbital launches a year, on average, but offered no timeframe"

Of course this ALSO depends on what you define as your "first-stage" being the aircraft or the "first" rocket stage

As well as various "S-&-A" parts pertaining to the rocket design itself I might point out

Randy

[antonioe]

of course those "wise men" were assuming a reusable launch vehicle with the development and recurring cost of the STS, an RLV built to keep the NASA centers occupied. They were not talking about any conceivable RLV. And since that is OT for this thread, I will leave it at that.
 ...

Well, I am sure that they did not assume a more expensive one, because then the 60 launches would not have covered the cost. With a cheaper vehicle with lower running cost, they would not need that many launches to make it cost effective. No?

Elmar and the others:

The "50-60" argument implies the same amount of "expensiveness" or "cheapness" for the expendable and the reusable; if we claim that "new space" (or commercial, or whatever) can develop a new reusable cheaper than NASA, why, so can they develop an equally cheaper than NASA expendable and the ratio still holds...

[Elmar Moelzer]

The "50-60" argument implies the same amount of "expensiveness" or "cheapness" for the expendable and the reusable; if we claim that "new space" (or commercial, or whatever) can develop a new reusable cheaper than NASA, why, so can they develop an equally cheaper than NASA expendable and the ratio still holds...

I am sorry, but I am not sure I can follow. I will repeat my question: What were the assumptions made for the service costs of the RLV versus the construction costs of the ELV? What were these assumptions based on? E.g. we all know that the shuttle needed a lot of manhours between flights and a lot of replament parts that would benefit from the power of scale (e.g. the more replacement parts produced, the cheaper the individual part).
Why should we assume that any RLV would require exactly the same as those assumed for the shuttle?
What about (reduced) payload of the RLV versus the ELV. I am sure they calculate that in, but what were the exact numbers they used for that? I just keep hearing the same "50 to 60 flights" quote, but it feels awfully out of context to me.

[Garrett]

One crazy idea, add a couple of spaceshipone/two-like feathers to the air launched first stage being designed by Orbital and bring it back as a reusuble first stage. I'm not an engineer so don't know the technical feasibility of such an aproach. I'd like to know your views on this idea. Also I don't know if there are any intelectual property issues that would prevent them from using this aproach, if it was feasible.
I'd really like your feedback on this.
LR

Welcome to the forum!
I think such a stage would have to glide forward, which adds cost to the recovery efforts that you have to account for. It could still be a winner, but any recovery mass added eats into the payload to orbit and that's very limited already.

I think such a stage would have major engineering problems to overcome:
 - The feathered structures would add significant drag, unless they were somehow tucked away.
 - In SS2, I think the maximum reentry speeds are of the order of Mach 3. Going on the current F9 first stage, IIRC a first stage for orbit insertion reaches speeds of the order of Mach 10. My armchair guess is that feathering at such velocities would not be feasible.

Oh, and welcome to the forum LR

[docmordrid]

IIRC Musk has said the F9R first stage will only hot Mach 6-ish, with a more vertical trajectory.

[deltaV]

Falcon 9 is off-topic here.

[JohnFornaro]

Well, F-9 used to be on topic, until SpaceX quietly acknowledged that the rocket had been designed to launch vertically, and bowed out.

[Comga]

I just read the FlightGlobal article on Stratolaunch, and it makes even less sense than ever.

They have built TWO giant hangers for a single "one off" giant aircraft.
They are building the center wing structure, the part that mates to the undefined to-be-carried rocket.
Wing designs are still undefined, not just being tweaked.
They are still aiming for a 6100 kg orbital payload.
Aircraft GTOW is up by 0.1Mlb to 1.3 Mlb.
They still don't know if the rocket will have solid or liquid propellant.

It must have been said before, but regardless of the number of stages, for a given payload, isn't starting mass a strong function of Isp and therefore the fuel chosen?  Doesn't that mean that the rocket mass will be much greater if the rocket is solid than if it uses liquid propellants?

This does not add up to the announced program.  Something else must be going on.

[JohnFornaro]

Not sure when they did it, but the Stratolaunch page has been updated, and so have the renderings of the vehicles. The aircraft looks very different, much less twin 747 than super WhiteKnight. The booster renders don't show the nozzles, but do appear to show three stages of similar length and a much wider faring. IMHO, that (plus the fact that's it Orbital) would imply all solids. But it's probably just notional.

http://www.stratolaunch.com/

Well, their video, which I would call unnecessarily grainy, still shows the SpaceX configuration and credit.

a) Review location of delta (or near-delta) - planform wing's cp location w.r.t., say, the apex of the triangle

b) Imagine where the WHOLE VEHICLE Cp (including the fairing) would be

c) compare with expected location of the aircraft wing's cp (quarter-chord?)

Okay....  How about this?

The only thing that flies back is Stage 1.  Which would be one more stage than anybody else is flying back.

[Lars_J]

Doubtful. The wing is supposed to be balanced for the entire LV when it is released, to assist in the pull-up maneuver - see here: http://forum.nasaspaceflight.com/index.php?topic=27520.msg1028020#msg1028020

I don't think it will be able be balanced to act as a fly-back first stage with the payload and top two stages removed. It seems implausible.

But I have been wrong before.

[Elmar Moelzer]

And the shuttle did need a lot of replacement parts,

No, it did not.  You have nothing to base this assertion on except for your petty and uninformed bias against the shuttle.

ET didn't have "a lot" of parts?

ET, tiles, and one could argue that the booster engines were basically rebuilt after every flight. But Jim does not even get the topic of the discussion or why I said that, anyway. The topic was not the shuttle, but what assumptions the "50 to 60 flights" were based on. I assumed that they thought that every RLV would need as many replacement parts as the shuttle did after every flight (and service time between flights). In this case, "many" is relative.

[yg1968]

Image of the Hangar:
https://twitter.com/PaulGAllen/status/317696319512801281
https://pbs.twimg.com/media/BGivHo-CcAAbjc_.jpg:large

Update:
http://www.flightglobal.com/news/articles/stratolaunch-marches-forward-383992/