Elon Musk jumps overboard from Paul Allen's GIANT MOTHERSHIP Stratolaunch Systems has turned to Orbital Sciences to get the world's largest air-launch-to-orbit system off the ground. Concept art of loaded Stratolaunch mission. Credit: Stratolaunch Giant jumbo-jet style heavy lifter Backed by billionaire Microsoft co-founder Paul Allen, the firm originally wanted to build an enormous …
Perhaps Balloon or Aircraft launched rockets sound good, but the actual numbers don't really work? For the aircraft there is the fuel to simply lift the aircraft as high as possible.
Israel is looking at air launches, but that is more a case of being able to have a launch point outside Israel. For some reason Rocket launches in Israel make the neighbours nervous.
@Mage: Orbital already performs air launches of Pegasus using a former Air Canada L-1011 jet: http://www.orbital.com/spacelaunch/pegasus/
The aircraft pretty much _replaces_ the first stage, and avoids having to have the launch vehicle deal with the same level of aerodynamic pressure, because the rocket engine is much more efficient (in thrust - drag terms) at ~38,000ft than at sea level. Plus, of course, there are limited numbers of launch sites that are geographically optimal (Kennedy/Canaveral and Vanderberg are too far north, for example).
It absolutely makes sense from an energy point of view.
Instead of accelerating the vehicle through the dense lower atmosphere at huge speed/cost you gently lift it high enough for the second stage to work.
You also get to choose your launch position depending on what orbit you want - that's why the mothership has such large range.
The downside is the limited size/mass of the payload, mounting it so that it's safely held horizontally under gravity and then vertically under thrust and the extra complexity of the parent aircraft and it's crew
When you air-launch, you never need to go vertical, and that accounts for a large part of the performance gain. When a conventional rocket takes off vertically, gravity opposes thrust and subtracts 1 gee from the net acceleration. When you are horizontal or near horizontal, gravity is perpendicular to thrust and does not slow you down.
Air-launch has an optimal flight angle early-on that is between horizontal and vertical, and the later parts of the flight are pretty much identical to other types of rocket. So it has less losses from fighting gravity in the early flight, and so better performance overall. The other gains you get are less drag loss and higher engine thrust, both from being at lower pressure, plus the actual altitude and velocity of the airplane.
The other part of the cost benefit besides performance is that an airplane has effectively an infinite operating life compared to one-use rocket stages. Thus the cost per flight of the airplane is much reduced. The cost of actual flying time (fuel and maintenance) will be ~$15,000/hr. This will be a tiny part of the total launch cost.
@Steve the Cynic
Apollo was a monumental accomplishment, but every piece of the Saturn 5 was thrown away after use save the command module that brought them home. The whole concept of today's space race is re-usability. That makes it cheaper to run and cost effective. Everything you see in the concept photo of the article can be reused many times making the cost of putting things in orbit relatively cheap.
NASA and the US Gov dropped the ball after Apollo 18 was cancelled. They stopped all lunar exploration for twenty years and slashed budgets. A continuous and steady effort to develop a presence in space and on other planetary bodies should be continued globally. Our future is out there.
@NoneSuch
Don't get me wrong, reusable is good. My question is more one of what adjective-of-size we should use to describe Saturn V (47 tonnes to the Moon, 120 tonnes to LEO) if 6 tonnes to LEO is "enormous"...
I'm conflicted partly because people keep talking about space operations as if sending 120 tonnes to LEO (regardless of reusability) belongs to the realm of science fiction, rather than being a piece of history.
Martin 47 came close, but the truth of the matter is, there is no adjective in the English language that adequately describes the size of the Saturn V.
If you go to Canaveral and look at the one they've restored and mounted in rests so you can walk it's length the experience of standing at the working end of the rocket is awe inspiring. If you've been to the Smithsonian and seen the engine they have on display you think you have an appreciation of how big the rocket was, but you don't. My friends and I have been to Canaveral several times and every time we stopped and stood there for 10 minutes just staring up at the nozzles. Then we'd slowly walk along the length of the rocket. Even when we knew that because of the other things we wanted to see, we didn't really have the time. So something else always got cut from our visits.
Witch Doctor icon because every time I've looked at that Saturn V I've felt like a primitive.
If my sense of proportion is not completely off whack, each of the 5 main stage engines of the Saturn V rocket was just slightly smaller than the tip of the rocket nose-cone you see on the picture in this article.
So yeah, it may have been able to lift a tad more than this air-launched rig.
How about the old (1988) Energia / Buran 100t -> LEO or 20T-geostat
http://en.wikipedia.org/wiki/Energia#Second_launch_.28Energia-Buran.29
worked pretty well, they simply ran out of money...
Or Zenit (currently in use-Ukraine->Sea Launch/Kazhakstan) 14T->LEO 6T->GTO
http://en.wikipedia.org/wiki/Zenit_%28rocket_family%29
In a study of 16 launchers, the Zenit-2 was, as of March 18, 2001, the lowest cost vehicle for achieving LEO in terms of payload weight per launch ($1,167-1,667 per pound or 2,567-3,667 per kg), and one of the lowest in terms of total costs per launch ($35–$50 million).
http://www.spaceref.com/news/viewnews.html?id=301
Or Angara (full test launch 2013?) 14-24T maybe up to 40T to LEO
http://en.wikipedia.org/wiki/Angara_%28rocket%29
including RD-191 motors
http://en.wikipedia.org/wiki/RD-191
Or if you like dodgy but ambitious LARGE antique prototypes:-
N1 90T->LEO 23.5T->Moon (planned) (1969-1972) (all went BANG!)
http://en.wikipedia.org/wiki/N1_%28rocket%29
Launch:- http://www.youtube.com/watch?v=Ux4TrOEhh0c
Equinox documentary on engines http://www.youtube.com/watch?v=rEX0IHIn0_4
Possibly the largest artificial non-nuclear explosion in history!
Apparently "first stage is the most powerful rocket stage ever built"
Buran was their Space Shuttle. It has the same strengths/weaknesses. Ultimately the weaknesses outweighed the strengths by a LOT:
Very high weight for reusable represented too much lifting-expense
Nasty rocket activity was too close to the payload and passengers
Cost too much to recycle for reuse (including too much checking/repair cost after each use)
It was an intoxicating thought, kinda like a bad marriage.
"But the money behind SKYLON and LAPCAT. And return Britain to the forefront of aviation"
You do know that REL do not want much more than their current 15% to be govt (of any country) funded?
Some of the REL staff remember just how much the men from the ministry (of any country) can f**k up a programme.
However if anyone has a spare £10m VC they are prepared to loose....
This is high cost/risk/reward stuff.
What benefit does this scheme provide?
If reduced fuel expenditure then the benefit is small: cost of fuel to launch from sea level to LEO is less than £200K.
If reduced vehicle costs, again the benefit is small: while expensive, the 4 engines (if using the SpaceX vehicle) saved would not provide a large benefit.
The largest benefit to be found is reuse of first stage rockets, which this scheme does not do.
The rocket-bodies needed for launch-from-altitude weigh MUCH less than rocket-bodes that can sustain a sea-level launch. The reduction of that weight and simplification of the mechanism could being substantial savings. The problem with Orbital's participation is that Orbital mainly uses solid rockets, and was working on liquid rockets. Solid rockets cannot be shut-off and restarted.
SpaceX is almost completely about liquid rockets (specifically, RP1 rockets).
Changing to Orbital will mean that EITHER they will use their solid rockets, which don't really benefit as much from launch at-altitude OR they will debug their troubled liquid rockets. This COULD be an opportunity for Orbital to get capital to re-adapt their liquid rockets for at-altitude launches and benefit both companies.
We will see...
"The rocket-bodies needed for launch-from-altitude weigh MUCH less than rocket-bodes that can sustain a sea-level launch."
Doubtful. Sea level rocket have mass stresses aligned with the thrust direction. A rocket here has to be strong both longways (from where the thrust comes) and crossways (mass on the mounting fixture).
A pressure fed could be lighter because it would need a lower tank pressure to support the same sized nozzle at sea level before flow separation started (roughly 0.4x ambient pressure).
" they will debug their troubled liquid rockets."
what AFAIK OSC only major liquid rocket stage is the Antares 1st stage, which is being done by Russia. Those engines are meant to be versions of the highest performance LOX/RP1 engines ever built.
They certainly weigh less because they start at 30K feet. The lateral vs longitudinal stresses are a mix, but there is less needed because of the initial weight reduction.
As you say, the engine pressures can be lower, giving potential cost reductions...
As for Orbital and liquid rockets. EVERYONE is pinching Russian tech (SpaceX, too). They Antares just isn't getting great launch tests, yet.
While I'm happy to see big engineering projects fly, the opinion I held when El Reg first put this story out there, back when it was SpaceX providing the big thrusty thing, still holds - This thing'll never fly.
Oh, I'm sure they can do the engineering & it's not impossibe to find the development money but what's it for? It's for the direct-to-GTO market. Existing players, SeaLaunch, at approx 100 million dollars a pop, able to do 6 tonnes direct to GTO. SpaceX, at approx 54 million dollars a pop, able to do about 4 tonnes to GTO, launching from about 29 (might be wrong but thereabouts) degrees north.
Both exist now, both are operating now. So this would have to cost less than 100 million dollars to put 4-6 tonnes into GTO, and less than 54 million to put less than 4 tonnes into GTO.
And unless the range of the aircraft has changed, it'll never reach the equator to launch directly to GTO unless it takes off from... Hawaii.
Which is a bit out of the way...
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