Will StratoLaunch Fly?

[Northstar1989]

On 9/19/2017 at 2:25 AM, Helmetman said:

@mikegarrison  You are very right, and it wasn't specifically to make fun of them.

But reading about this myself for some time already and the topic replies covering the implications, lack of need, maybe net loss for required infrastructure (runway) and everything else gets me annoyed about the fundamental priorities of this project.

The physics make sense (>50% reduction in first-stage mass, fewer engines, shorter burn-time).  There are PLENTY of payloads in the size-range this thing can launch (6 tons to LEO with a "Falcon Air" sized rocket).  And it's just REALLY COOL (TM).

I have no doubt that it COULD be made to work, if they could rope SpaceX back into building them a rocket.  I'm not sure any other company has the gusto and daring to build something that will do the job well enough, though...

 

[Northstar1989]

On 9/14/2017 at 10:52 AM, wumpus said:

 The obvious issue the stratolaunch backs itself into is that it strictly limits the size of the satellite it can launch, while still requiring basically the same number of flights to design the rocket as the big boys.  The Delta-II was able to scale itself by adding various numbers of SRB boosters ("more boosters") and the Delta-Heavy and Falcon-Heavy "simply" combine boosters to build a vastly larger rocket.  These are then more efficient and can lob large numbers of "stratolaunch sized" satellites into orbit even more efficiently than a small stratolaunch rocket even with it's 50% efficiency.

Note that how this thing gets to Mars is only one of Elon Musk's concerns.  Recovery is a particular bugaboo of his, and it isn't clear that spacex could use current recovery methods to recover Falcon Air.  But the real reason Spacex still exists at all is the CRS program.  CRS requires 2-3 tons of cargo and is delivered by a 2 ton dragon capsule.  If Spacex was tied to Falcon air and couldn't cut the dragon down to fit the falcon air payload requirements, spacex would go bankrupt.  Just from memory, CRS is one of the lightest LEO payloads falcon 9 carries (excluding multiple launches),  and I don't see how they could afford to justify falcon air without CRS.

These are baseless accusations.  The Delta II had a MAXIMUM payload of 6,100 kg with a full booster array.  The Falcon Air, launched from the Roc, would have been able to carry 6 tons without any modifications (that's BEFORE you account for engine-upgrades to the Merlin since Falcon 9 v1.0, now making it one of the best Kero/LOX engines in the world).  Size is clearly not an issue here.

CRS requires 4-5 tons of mass to LEO.  Falcon Air could deliver 6.  Payload capacity is just a straw-man here, and for the record, SpaceX has a MASSIVE back-log of pre-ordered commercial launches: they are hardly at risk of going bankrupt.

I hate to say it and don't mean to sound mean or rude, but your entire argument here boils down to "it can't launch enough payload" with some mild hating on SpaceX sprinkled in.  But, with a payload-capacity that EXCEEDS the Delta 2 in any of its configurations, despite that being the rocket you point to as a contrast, your argument really doesn't hold up here...

I hope we can agree to amicably move to further points of discussion here: size and payload-capacity are simply NOT an issue...

 

Regards,

Northstar

Edited September 21, 2017 by Northstar1989

[Northstar1989]

On 9/14/2017 at 10:31 AM, DerekL1963 said:

That doesn't make what Nibb said wrong.  That increase in first stage mass is cheap - it's all tankage and fuel.  (And setting aside that the mass savings from a smaller first stage are partially offset by the mass increases in all stages to allow for horizontal carry and to withstand the stresses of the drop.)

 

But this discussion isn't just about the physics.  It's also about the costs, particularly the elephant in the room - the launching aircraft.  (Estimated at $300 million six years ago for Stratolaunch, almost certainly much higher than that in reality.)  That's long been the basic economic problem for air launch systems, the economics only make sense if you're launching a significant number of payloads.  Otherwise, you end up with Pegasus, one of the more expensive civilian launchers rather than being one of the cheapest.  (Another part of this is because air launch doesn't save any man hours in the launch campaign, in fact it adds to them.)

First Stage mass is NOT cheap.  Mostly because it's not just all "tankage and fuel" here- you also need additional engines and turbopumps- which are the single most difficult, failure-prone, and expensive part of a rocket to manufacture...

6 engines instead of 9 reduces the chance of launch-failure.  Using a tried-and-true jet engine on a plane body that while large, let's be honest here, really isn't that revolutionary also means the carrier plane itself really doesn't have much chance of failure.  The most difficult aspect here BY FAR is the actual air-launch itself: the process of decoupling a plane and a rocket in the air, and firing the rocket off without crashing into the plane or a failure of the rocket engines to ignite...

As for the $300 million, that's about what SpaceX spent developing the Falcon 9 v1.0 (before the later upgrades and reusability-testing), a cost thst simply knocked the socks off any of their competitors (which typically spend 3-4x that much for a comparable rocket).  It's not really that much money in R&D costs at all.  If Paul Allen is not fudging his figures here at all then that's a BARGAIN for the cost of developing one half of a launch system- and even cheaper compared to R&D costs for most large commercial passenger or cargo jets...

So, $300 million for the plane and another $300 million for a Falcon Air rocket (maybe less- since SpaceX already has a mature design for the Merlin engine).  That's still only $600 million for a 6 ton to LEO rocket- still less than the maybe $750 million to $1 billion pricetag that a comparable payload-capacity would cost for a more traditional rocket...

What's more, half of those R&D costs are already SUNK- meaning that Stratolaunch won't be able to take back all the spending they've done on the Roc no matter what happens from here on out.  So only $300 million more to develop a rocket in the 6 ton payload range is a great bargain, and they would be stupid not to take therm up on the offer if SpaceX came back to them and offered to develop them a Falcon Air (with further launches provided at a much lower price) for $300 million...

And SpaceX would be even dumber not to make such an offer in the first place, as they get the R&D money no matter whether the Falcon Air finds a market or not.  If they could develop a Falcon 9 v1.0 for $300 million from scratch, they could certainly build a Falcon Air with only 6 engines for less than that- and the experience working with the unusual aerodynamic regime of air-launch would probably also be beneficial to their later developing a landing-system for the ITS.

SpaceX could PROBABLY even experiment with building a 2-engine rocket based on their upcoming Raptor Meth/LOX engine design instead: which would be lighter and have a higher payload-capacity due to the higher ISP (334/361 seconds SL/Vac for the Raptor vs. 282/311 seconds for the Merlin), higher initial thrust (6,100 kN vs. 5070 kN), deeper throttling (down to 20% vs. A minimum of 60%), and even a higher expected Thrust--Weight-Ratio for the Raptor than the Merlin, which might equate to lower engine-mass despite the increased thrust...

Note that the Raptor's higher chamber-pressure means they could equip an even higher expansion-ratio nozzle for air-launch to the Raptor than the Merlin (the ability to use higher expansion-ratio nozzles is one of the PRIMARY advantages of air-launch, even Elon Musk has noted this despite his criticism of the concept).  And, it would be a great opportunity for SpaceX to flight-test their Raptor engine WITHOUT needing to throw out a perfectly good Falcon 9 configuration to replace it with one based on the Raptor instead of the Merlin...

 

Ultimately, I believe the Roc will fail, but not because of any inherent weakness of the Stratolaunch plan- simply because SpaceX, the only company that could make this work, is simply too reluctant to work on the development of an air-launched rocket: which is ironic for a company thst seems so remarkably audacious the rest of the time...

Regards,

Northstar

Edited September 21, 2017 by Northstar1989

[DerekL1963]

1 hour ago, Northstar1989 said:

What's more, half of those R&D costs are already SUNK

Ahh...  the sunk cost fallacy rears it's ugly head once again.
 

1 hour ago, Northstar1989 said:

And SpaceX would be even dumber not to make such an offer in the first place, as they get the R&D money no matter whether the Falcon Air finds a market or not.

Alongside the broken window fallacy...

 

1 hour ago, Northstar1989 said:

First Stage mass is NOT cheap.  Mostly because it's not just all "tankage and fuel" here- you also need additional engines and turbopumps- which are the single most difficult, failure-prone, and expensive part of a rocket to manufacture...

Only if you reduce the size of your payload.   Which just brings you back to the same starting point.

[Northstar1989]

On 9/21/2017 at 1:54 PM, DerekL1963 said:

Ahh...  the sunk cost fallacy rears it's ugly head once again.

Sunk costs are a known economic fact of decision-making, and you are completely reversing sunk cost theory- which you probably do not understand (and which theory shows *I* am correct, not you).

The "Sunk Cost Fallacy" is the human tendency to treat costs which are, in fact, already "sunk" (sunk costs) in future decision-making as if they have not already been spent.

I.e. to not finish developing a launch-system that is already $300 million in the hole because the additional, say, $250 million to do it would add up to a "higher" cost than starting over on a different design which might cost $450 million from start to finish, but that had not yet been started.

In that scenario abandoning the project and starting from scratch on a new rocket design would cost more- simply finishing the system already $300 million down is the cheaper option as it costs just $250 million, not $450 million (so you save $200 million).  Starting over would be an example of the Sunk Cost Fallacy.

The fallacy actually SUPPORTS my point here, as finishing the Roc is a cheaper option than starting on a new launch system from start to finish, regardless of how much money has already been sunk into the project- at this point it is cheaper to proceed than to start over with a new project.

Put a different way, the costs of developing the Roc have already been spent, so that carrier plane is essentially "free" from a standpoint of future decision-making as no course of action will change that cost.

And, it will be cheaper to develop and build/operate an air-launched rocket to be released by the Roc due to the smaller size needed to attain orbit than a ground-launched rocket with the same payload-capacity.  The disadvantage of an air-launched rocket over a ground-launched one is the R&D costs of developing the carrier-plane: but the carrier plane has already been developed, so those costs can be forgotten- and going forward it's cheaper to develop an air-launched rocket for the Roc than to develop a ground-launched rocket (as bigger rockets are more expensive to debelop). Already expended R&D costs don't matter- only the remaining costs to project completion.

You don't seem to understand the meaning of the fallacy, as it actually supports my point, and by bringing it up you have actually given me ammunition to use against you, since it illustrates why I am right: given that building an air-launch rocket for the Roc is the cheapest option going forward; any past costs are already "sunk" and it would be an example of the fallacy to incorporate them in determining the cheapest option going forward...

https://en.m.wikipedia.org/wiki/Sunk_cost#Loss_aversion_and_the_sunk_cost_fallacy

On 9/21/2017 at 1:54 PM, DerekL1963 said:

Alongside the broken window fallacy...

Nothing about selling a product and not being responsible for whether the consumer can put it to good use constitutes destruction, which is what THIS fallacy is about (specifically, falsely thinking that destruction is good for the economy).

The Falcon Air was and is a good product.  SpaceX could sell it in good faith.  It really doesn't matter to them whether Stratolaunch can find a use for it or not- they're not intentionally selling them a faulty product in the hopes it will break, nor would they be trying to destroy the company itself in the hopes of gain.  Nothing about this decision generates destruction or somehow dooms Stratolaunch.

In fact, the Broken Window Fallacy works in my FAVOR here, since refusing to sell a rocket to Stratolaunch is actually what has the greatest risk of generating destruction.  As has Bern said by multiple people multiple times, Stratolaunch is likely to go under if they can't find somebody to build a rocket to air-launch from the Roc for them.  They are LEAST likely to go under if SpaceX designs them a Falcon Air-launch as it is the best posdible product for the Roc they can hope for.

On 9/21/2017 at 1:54 PM, DerekL1963 said:

Only if you reduce the size of your payload.   Which just brings you back to the same starting point.

You clearly don't understand what I wrote.  My entire point was that you get the SAME payload to orbit with fewer engines, not a smaller payload with fewer engines.  My response you quoted was in reply to the incorrect assertion that it wouldn't cost that much to just build a larger first stage rather than air-launch the rocket: in reality it would cost MILLIONS more, *per launch*.

A Falcon Air as proposed would have 4 engines, but launch just as much payload to orbit as a 6-engine ground version.  The heavier, theoretical 6-engine rocket I was also referring to as a Falcon Air at times would have the same payload-capacity as a Falcon 9, but only require 6 engines...  Either way, it's a third less launch stage engines for the same payload (for a design where you just cut in half the size of the first stage- in reality you might want to cut mass off both the first AND second stages for even greater mass-savings...)

Edited September 23, 2017 by Northstar1989

[insert_name]

It looks like now they are planning to develop their own engine

http://spacenews.com/nasa-agreement-sign-of-stratolaunch-engine-development-program/

[wumpus]

Looks like they want to test fly the thing.  Still no word on any rocket being developed for it to carry: multiple pegasus ruin most of the point of a pegasus.  And Orbital already has a perfectly good carrier that is almost certainly cheaper to fly.  My guess is a last ditch hope some greater fool will take it off their hands.

[Thor Wotansen]

I'm actually surprised nobody's stepping up with vehicle designs for this.  The system should be capable of incredible flexibility in launching payloads to pretty much anywhere, regardless of ground level weather, and with much greater launch window flexibility.  If you use solid rocket stages, you could keep the cost per launch very low and not have to be tied to a specific geographical launch area.

[DerekL1963]

2 hours ago, Thor Wotansen said:

I'm actually surprised nobody's stepping up with vehicle designs for this.  The system should be capable of incredible flexibility in launching payloads to pretty much anywhere, regardless of ground level weather, and with much greater launch window flexibility.

I'm not surprised at all.  That capability comes at a steep cost, in the form of a very expensive one-of-a-kind aircraft.  Amortizing that expense (including servicing the debt) significantly increases your launch costs...  On top of that, total system performance is sharply limited by the carrying capacity of the aircraft.  On top of that it's still not clear that there's a lot of demand for that kind of launch capability, in terms of throw-weight (which isn't impressive) or lack of limits.

 

3 hours ago, Thor Wotansen said:

If you use solid rocket stages, you could keep the cost per launch very low and not have to be tied to a specific geographical launch area.

On the contrary - you're very tightly limited in geographical launch areas.  They have to be within range of an airfield that can handle the aircraft and which will allow for the handling of several tons of low explosives (in the form of solid fuel).  Plus you need the ability to support the payload, or the payloads have to be self supporting or require little-to-no support.

It's not nearly as simple, or cheap, as people would like to think.

[wumpus]

20 hours ago, DerekL1963 said:

I'm not surprised at all.  That capability comes at a steep cost, in the form of a very expensive one-of-a-kind aircraft.  Amortizing that expense (including servicing the debt) significantly increases your launch costs...  On top of that, total system performance is sharply limited by the carrying capacity of the aircraft.  On top of that it's still not clear that there's a lot of demand for that kind of launch capability, in terms of throw-weight (which isn't impressive) or lack of limits.

Those costs aren't going to be paid (except by Paul Allen and co).  There are basically four paths:

mothball the thing (presumably not happening.  It seems to be complete)
sell and take whatever money they can (then the buyer doesn't need *quite* the return on investment
bankruptcy (and a situation similar to the above, although Stratolaunch people are more likely to wind up with the plane)
eat the loss and try to launch things

None of "the big boys" seem all that interested in building a rocket for them (apparently Orbital does a bit of consulting, but isn't under contract to build a rocket).  On the other hand, I'd assume that Rutherford Labs (the Electron rocket people) and any competitors building small rockets would be interested.  Most of the reasons to avoid this type of thing would be deep uncertainty of the plane flying (a few test flights might make investors willing to at least ink deals) and fear of tying themselves to the small rocket market (which isn't that profitable, look at how often Pegasus flies).

[Nibb31]

The reason to avoid this thing is operational cost.

An aircraft that flies only once or twice a month is an aircraft that is going to lose money. Airplanes are expensive, so it is essential to maximize their operational time. Most aircraft, from commercial airliners to fighter jets to small tourism aircraft spend most of their time either flying or in maintenance.

300 million is about the price of an Airbus A380. So Stratolaunch is not that expensive for a large custom-built aircraft. The main difference is that an A380 will spent 80% of its time flying commercial passengers and recouping its cost, and 20% in maintenance. It probably amortized its ownership cost over something like 10 years.

Stratolaunch on the other hand (like Pegasus before it) will spend most of its operational life in the hangar. A plane sitting on the tarmac is a plane that's losing money. If it flies 50 times less than an A380, it means that each hour of flight will cost 50 times more and the cost of operating it will rapidly become prohibitive, meaning that it will be much less competitive than simply designing a slightly larger first stage for your rocket.

Edited March 6, 2018 by Nibb31

[mikegarrison]

On 3/2/2018 at 10:26 AM, wumpus said:

Still no word on any rocket being developed for it to carry

No longer true. The Seattle Times is reporting today that the Stratolaunch people are working on an orbital spaceplane for Allen. It would launch from under the stratolaunch lifter and be capable of reaching the ISS. It apparently has the code name "Black Ice".

Edited March 7, 2018 by mikegarrison

[DerekL1963]

2 hours ago, mikegarrison said:

The Seattle Times is reporting today that the Stratolaunch people are working on an orbital spaceplane for Allen.

0.o  Stratolaunch *is* Paul Allen.   And that's not what the article says, it says they're "considering" developing such a vehicle.  Which I read as putting pressure on an as yet unknown potential partner - "if you don't do it, you'll miss out because we'll do it ourselves".  Either that or Allen actually has finally lost it completely.

On top of that, the notional specs of the proposed vehicle are (to put it mildly) mind boggling (and not in a good way).  An unmanned space shuttle sized vehicle that's all but an SSTO capable of reaching ISS?

[mikegarrison]

5 hours ago, DerekL1963 said:

0.o  Stratolaunch *is* Paul Allen.   And that's not what the article says, it says they're "considering" developing such a vehicle.  Which I read as putting pressure on an as yet unknown potential partner - "if you don't do it, you'll miss out because we'll do it ourselves".  Either that or Allen actually has finally lost it completely.

On top of that, the notional specs of the proposed vehicle are (to put it mildly) mind boggling (and not in a good way).  An unmanned space shuttle sized vehicle that's all but an SSTO capable of reaching ISS?

I know, I know. But the guy has so much money ... if he wants a toy, he usually gets it, somehow or another.

About a year ago I was walking around in his personal collection of flying WW2 airplanes (open to the public). He's got the White Knight airplane stashed away in there too, up in the rafters like its kind of an afterthought.

Edited March 7, 2018 by mikegarrison

[wumpus]

2 hours ago, mikegarrison said:

I know, I know. But the guy has so much money ... if he wants a toy, he usually gets it, somehow or another.

About a year ago I was walking around in his personal collection of flying WW2 airplanes (open to the public). He's got the White Knight airplane stashed away in there too, up in the rafters like its kind of an afterthought.

A SSTO shuttle isn't just expensive, it may well be on the wrong side of physical limits.  If you don't drop the fuel tank (and stop being "fully reusable"), it almost *certainly* is on the wrong side.  Staging is simply required for the Isp used in currently available fuels, and there is no reason to believe Allen has anything up his sleeve beyond a whole lot of money.

A two stage shuttle (presumably both landing like planes/gliders) still has problems, but might be considered easier/cooler/less "me-to" than a vertical landing.  I don't know Stratolaunch's cost/schedule, but building a rocket for it would presumably be a project of similar scope.  I'd expect a rocket sized for stratolaunch would be a more complex project, but presumably Stratolaunch already knows from working with Scaler (who built both the White Knight and Space Ship 1).  BFR is well along the way in design.  Presumably New Glen is also coming along.  I'd assume at least one of them will be flying while Stratolaunch is grounded/reduced to ferrying Pegasus regardless of how fast Allen spends money.

There's also the issue that the Electron can already send more payload to orbit than any SSTO light enough for Stratolaunch to carry.  If any work starts on the design, that "nearly SSTO" will drop down to "just getting out into space".

[DerekL1963]

5 hours ago, wumpus said:

A SSTO shuttle isn't just expensive, it may well be on the wrong side of physical limits.

That's kind of my point.  Thanks to Musk and Bezos we've gotten used to billionaires accomplishing amazing things by defying received wisdom and common sense.  But what most folks may not realize is that no matter how much it seems so, neither has actually tried to defy the laws of physics. (Or economics and GAAP.)  Allen is trying all three, at once.

Edited March 7, 2018 by DerekL1963

[ment18]

A SSTO isn't impossible.  Since they are launching at a significant altitude you can use vacuum engines, without doing the stuff rs 25 had to do.  Depending on how much Dv they save from high altitude launch and the small forward speed, a significant mass fraction would be possible with engines similar to rl 10s.  At 9000dv to orbit, which is probably a bit high, you could get a payload fraction close to 5%.  This only accounts for engine and tank mass, so other structural stuff will cut into that severely, and a reusable vehicle borders on impossible due to heatshield mass and wings/landing prop.

[DerekL1963]

No, an SSTO isn't theoretically impossible.  Just very, very difficult to accomplish affordably and with a useful payload in the real world (which is rather messier, more complicated, and less cooperative than the theoretical world).

 

[insert_name]

http://spacenews.com/stratolaunch-planning-first-aircraft-flight-this-summer/

[tater]

 

[sh1pman]

Spaceplane is interesting. Single stage or multistage? Orbit or suborbital?

[sh1pman]

“Stratolaunch confirmed that, in addition to those launch vehicles, it is in the design study phase for a reusable spaceplane that would be launched from the aircraft. That vehicle would initially be used for cargo, but a “follow-on variant” would be able to carry astronauts.”

https://spacenews.com/stratolaunch-confirms-launch-vehicle-development-plans/

Is something like that even possible? Single stage spaceplane that packs 8.5 km/s dv and has wings, heat shield and everything else that a spaceplane needs? And has enough margin for cargo or astronauts? What is it, an air-launched BFS?

[magnemoe]

12 minutes ago, sh1pman said:

“Stratolaunch confirmed that, in addition to those launch vehicles, it is in the design study phase for a reusable spaceplane that would be launched from the aircraft. That vehicle would initially be used for cargo, but a “follow-on variant” would be able to carry astronauts.”

https://spacenews.com/stratolaunch-confirms-launch-vehicle-development-plans/

Is something like that even possible? Single stage spaceplane that packs 8.5 km/s dv and has wings, heat shield and everything else that a spaceplane needs? And has enough margin for cargo or astronauts? What is it, an air-launched BFS?

yes, that is the problem, 12 km and mach 0.9 don't help much outside of small rockets there drag hurt a lot and you can start with vacuum engines. 
For small stuff you can also use an fighter jet as fist stage for supersonic and higher attitude. 

Yes you could build an huge mach 6 plane capable of releasing an significant payload in near space. 
This would require you to match the specifications of an  Valkyrie bomber, an X15 rocket plane and an 747 cargo plane. 
Yes you could build it but it would be expensive as in the moon program, rockets are far simpler, yes BFR will be way cheaper. 

[sevenperforce]

On 8/20/2018 at 11:01 AM, sh1pman said:

Spaceplane is interesting. Single stage or multistage? Orbit or suborbital?

Looks like there would be space along the spaceplane's fuselage for a pair of simple crossfed boosters.

[wumpus]

On 8/20/2018 at 11:01 AM, sh1pman said:

Spaceplane is interesting. Single stage or multistage? Orbit or suborbital?

Appears drawn as single stage, which strongly implies suborbital.

Note that the Minotaur 1 used a modified Pegasus (Orion 38) rocket to put a 1.7 ton load into LEO (I think.  That might be with the upgraded Star engine.  Wiki isn't explicit or its usual infallible self).  Even so, strapping additional stages to a pegasus in an effort to launch .5tons to GTO instead of LEO is likely a useful thing for a Pegasus (and launch into GTO makes much more sense for air-launch).  Note that I doubt that anyone would be too worried moving an engine/nozzle designed for 40,000 feet and above to vacuum only flight (if not just grab the nozzle from minotaur I or IV).

As far as "what's changed", I'm guessing that management changed.  Once Northrup Grumman acquired Orbital-ATK, somebody thought it would be a great idea to build a rocket for Paul Allen.  Or maybe Paul Allen thought that if NG wouldn't build for him he'd have to build for himself.  But I'd be pretty surprised if the first effort didn't build on the Pegasus.