Stratolaunch: General Company and Development Updates and Discussions

[Robotbeat]

You would obviously set the "abort" parameters a lot more liberally than if you can abort without losing the rocket. Tell me: were all those pad aborts we keep hearing of really going to lead to a failed launch? A significant fraction (and, just a guess, the large majority) could probably have launched successfully just fine.

Obviously, if you can do a pad abort and just recycle the rocket in a couple hours, you're going to set the criteria for aborting (before lift-off) a lot more strictly, since your cost in case of a false alarm is a lot less.

[dbhyslop]

Point taken.  I remember some discussion of this during the Falcon launch where it was an issue but unfortunately I don't have the background to understand the trades that go into those abort criteria.  Nonetheless, given a choice I'd prefer to ride the one that launches from the ground.

[Rocket Science]

You would obviously set the "abort" parameters a lot more liberally than if you can abort without losing the rocket. Tell me: were all those pad aborts we keep hearing of really going to lead to a failed launch? A significant fraction (and, just a guess, the large majority) could probably have launched successfully just fine.

Obviously, if you can do a pad abort and just recycle the rocket in a couple hours, you're going to set the criteria for aborting (before lift-off) a lot more strictly, since your cost in case of a false alarm is a lot less.

An abort on the ramp or during takeoff would be interesting. I hope the carrier craft crew would have some means to escape and ejection could return you to any plume on the ground. All need to be considered…

[zaitcev]

Here's an apropos quote from Elon Musk:

http://www.nasaspaceflight.com/2006/08/spacexmusk-the-rocket-business/

There is a fundamental difference in architecture between ourselves and the Pegasus. I think if you were the smartest person on earth you could not make the Pegasus cheap.

The reason I say that is because it is a five stage rocket. You’ve got an airplane, which is a dedicated Lockheed L-1011. No matter how many times you launch, you have to maintain that plane at several million dollars per year. You have to have dedicated pilots.

Your range safety is much more complex because you essentially have a man-rated system – you are interacting a rocket and a plane with people on board, and then launching it with maybe 20 or 30 feet separating the pilot and that rocket. So I think that complicates things.

Then you have three solid rocket motor stages, including a complete hypersonic airplane in the first solid rocket stage. And then you have the fifth stage, which is the liquid apogee HAPS stage. So if you were the smartest person on Earth, I don’t think you could make that system very cheap.

If you look at ours in contrast: it is a two stage rocket, no wings, no control surfaces, both stages are the cheapest propellant you can use, LOX/Kerosene.

The animation shows a manned carrier airplane and the "complete hypersonic airplane" with a triangular wing. Why such a change of mind? Because this time Elon is spending someone's else money.

[jongoff]

Point taken.  I remember some discussion of this during the Falcon launch where it was an issue but unfortunately I don't have the background to understand the trades that go into those abort criteria.  Nonetheless, given a choice I'd prefer to ride the one that launches from the ground.

My concern is just that "relaxing constraints" could end up getting you into trouble.  If those constraints aren't thought to increase the odds of getting a good flight, then why are they there in the first place?  If they do increase the odds of getting a good flight, then aren't you still playing risky games with relaxing them to increase the light probability?

For a VTVL powered landing, I can totally see having the landing ignition requirements be a lot looser, since the engine only has to hold together for a few seconds, and you can probably tolerate some hardware rich combustion if it gets the engine on the ground safely.  But anyway, my biases are showing.

~Jon

[Lee Jay]

I do wonder what Rutan would think of Jon's gamma-maneuver (or whatever you call it), which should allow a sizable increase in payload without increasing the size or mass of the rocket itself. Sounds a little scary, to be honest. Scary in a good way.

I hear Kirk ran the idea by him about 5-10 years ago...the reaction was (IIRC--third hand info here) entertainingly emphatic...  Honestly, I think the only way they'd try something like that is if someone did a subscale demo first.

What is it?

Oh sorry, I wasn't clear.  The answer supposedly started with something like "There's no way in hell you're going to..."

Third hand info, and he may very well either have changed his mind or be open to reevaluating the view based on data and demonstrations.  At least during the press conference he mentioned the idea of putting rocket engines on the carrier plane as one option they had traded over the years.  But the idea may have somewhat of an uphill battle to convince him/others of its sanity. :-)

~Jon

I had a discussion a while back with Antonio Elias here on NSF about using what I called a "zoom launch".  The idea is to place the carrier aircraft into a shallow dive to pick up speed, and then pull up hard and release the rocket at the proper angle, thus avoiding most or all of the turning losses that the wing on Pegasus is supposed to also help to mitigate.  I've simulated this a little (don't ask) and I still don't see exactly why this wouldn't work, but I could imagine some implementation details that could be a problem.

[Jim]

Expand a still from the media to your full screen and measure the ratios.  If the wingspan is 117 meters, then the rocket they show there is 5 meters diameter in my estimation. 

It isn't, it is a F9 type core

[Rocket Science]

Some other twin conversion carrier aircraft...

http://www.pmview.com/spaceodysseytwo/spacelvs/sld039.htm

[simonbp]

I had a discussion a while back with Antonio Elias here on NSF about using what I called a "zoom launch".  The idea is to place the carrier aircraft into a shallow dive to pick up speed, and then pull up hard and release the rocket at the proper angle, thus avoiding most or all of the turning losses that the wing on Pegasus is supposed to also help to mitigate.  I've simulated this a little (don't ask) and I still don't see exactly why this wouldn't work, but I could imagine some implementation details that could be a problem.

That sounds pretty cool, and doable with the design they're showing. The structural loads on the wing roots at the point you pull up might be a killer, though.

[edkyle99]

Launch everyday from everywhere: stratolaunch.com! The new project by Mr. Allen.

http://Http://www.stratolaunch.com

Largest aircraft ever. 

The problem is, it is still not big enough.

 - Ed Kyle

[robertross]

Some people have asked if I'm involved, or AirLaunch or t/Space.  The answer is no to all three.

Perhaps someday I can comment, but not today.  NDAs and confidences are involved.  Sorry.

No worries here - I totally understand. Thanks for the note.

[Rocket Science]

Launch everyday from everywhere: stratolaunch.com! The new project by Mr. Allen.

http://Http://www.stratolaunch.com

Largest aircraft ever. 

The problem is, it is still not big enough.

 - Ed Kyle

Aw, come on now Ed… Let’s not cloud the issue with facts…

Robert

[Lee Jay]

I had a discussion a while back with Antonio Elias here on NSF about using what I called a "zoom launch".  The idea is to place the carrier aircraft into a shallow dive to pick up speed, and then pull up hard and release the rocket at the proper angle, thus avoiding most or all of the turning losses that the wing on Pegasus is supposed to also help to mitigate.  I've simulated this a little (don't ask) and I still don't see exactly why this wouldn't work, but I could imagine some implementation details that could be a problem.

That sounds pretty cool, and doable with the design they're showing. The structural loads on the wing roots at the point you pull up might be a killer, though.

I think the g-load could be kept under 1.5, which is equivalent to a decent turn.

If it buys you a couple hundred m/s saved, maybe it's worth beefing up the structure a bit.  Don't forget, by the time you get to this point, you've already burned off quite a bit of jet fuel.

[Lee Jay]

Launch everyday from everywhere: stratolaunch.com! The new project by Mr. Allen.

Http://www.stratolaunch.com

Largest aircraft ever. 

The problem is, it is still not big enough.

 - Ed Kyle

Heh!  When I envisioned this long ago, it had 6-8 GE90-115Bs.

[go4mars]

Here's an apropos quote from Elon Musk:

http://www.nasaspaceflight.com/2006/08/spacexmusk-the-rocket-business/

Thanks for posting that.  This was interesting too:

"We pay $1.90 per gallon of rocket propellant grade Kerosene…[laugh]…I can’t fill my car up for that…and the liquid oxygen in Texas – unfortunately in Kwajalein it ends up being a little more expensive than I’d like – but certainly in the continental United States you can actually buy liquid oxygen for about 40 cents per gallon."

[neilh]

Here's an apropos quote from Elon Musk:

http://www.nasaspaceflight.com/2006/08/spacexmusk-the-rocket-business/

There is a fundamental difference in architecture between ourselves and the Pegasus. I think if you were the smartest person on earth you could not make the Pegasus cheap.

The reason I say that is because it is a five stage rocket. You’ve got an airplane, which is a dedicated Lockheed L-1011. No matter how many times you launch, you have to maintain that plane at several million dollars per year. You have to have dedicated pilots.

Your range safety is much more complex because you essentially have a man-rated system – you are interacting a rocket and a plane with people on board, and then launching it with maybe 20 or 30 feet separating the pilot and that rocket. So I think that complicates things.

Then you have three solid rocket motor stages, including a complete hypersonic airplane in the first solid rocket stage. And then you have the fifth stage, which is the liquid apogee HAPS stage. So if you were the smartest person on Earth, I don’t think you could make that system very cheap.

If you look at ours in contrast: it is a two stage rocket, no wings, no control surfaces, both stages are the cheapest propellant you can use, LOX/Kerosene.

The animation shows a manned carrier airplane and the "complete hypersonic airplane" with a triangular wing. Why such a change of mind? Because this time Elon is spending someone's else money.

Also keep in mind that he's comparing the Pegasus and the Falcon 1 in that remark. The economics change a fair bit when you increase the payload by an order of magnitude.

[fotoguzzi]

396 comments!

Well, I will ask these questions and cross them out as I find them already covered in the comments as I plow through said comments:

Perhaps this plane could launch rockets into funny orbits without having to fly over cities. Are there that many funny orbits that are needed?

Does the initial altitude and speed really help all that much with cost? What are we saving? Fuel?

Is the cost per kg lower or is it just that one can get that kg exactly where it needs to be?

Is there something about an air launch that makes more parts recoverable?

Well, back to reading the thread....

[Proponent]

Perhaps this plane could launch rockets into funny orbits without having to fly over cities. Are there that many funny orbits that are needed?

Being able to move the launch point makes for more frequent launch windows to, for example, the ISS.  How important that is depends on how frequently you need to fly.

Does the initial altitude and speed really help all that much with cost? What are we saving? Fuel?

The speed provided by an air launch is not very significant.  What is significantly beneficial is that the lower air pressure at ignition permits a greater expansion ratio for the first-stage engines, making them more efficient.  Starting above well over half of the atmosphere reduces drag losses.

[simonbp]

Does the initial altitude and speed really help all that much with cost? What are we saving? Fuel?

There's a wonderful post on this forum by Antonio Elias, the original designer of Pegasus, about the advantages of the design. Effectively, it's more performance and more flexible launch operations.

The performance comes from launching in lower-pressure high-altitude air (which increases the rocket's efficiency) and from the wing providing lift to the rocket, reducing the losses due to gravity and drag. The flexibility comes from being able to launch in locations where building a launch pad is too expensive (i.e. anywhere other than established sites), and to be able to go around bad weather.

It's obviously not a smoking gun (as evidenced by the lack of any Pegasus launches this year), but it could be enough to be cheaper than Orbital's Antares (ex-Taurus II), the main competition in this range.

Speaking of which, I wonder if Allen initially offered the booster contract to Orbital; it seems much better suited to an air-launched Antares than a foreshortened Falcon 9...

[Robotbeat]

Antares has a few of differences: Not entirely domestic, hasn't flown, solid upper stage (i.e. harder to carry around when the rocket isn't fueled up... upper stage is always fueled), and possibly higher cost compared to foreshortened Falcon 5 (whatever). There are a lot more subcontractors to deal with for the different parts of Antares since that's Orbital's style (and it has suited them well in the past) compared to SpaceX's vertically integrated approach.

I think it's interesting that both of Elon's big projects, Tesla and SpaceX, have taken the vertical integration approach and now both are selling the heart of their primary product (i.e. electric drivetrain to Toyota and others and Falcon 5 to Stratolaunch) as a contractor to what some might call competitors. A couple of reasons for that: 1) Elon is very ambitious, pushes for something really great (with a great team), they partially succeed, but he over-steps and so sells out partially to competitors... 2) Elon possibly cares more about the technology succeeding in a way that changes the landscape than that it's "his." Maybe that last one is a little too generous (Musk is incredibly cocky, and it probably hurts his ego a bit that he sells out... sometimes learning a little humility can be good for ya). Either way, I don't really care who is making electric cars or launching rockets, as long as they're cheap and work well.

I wish Stratolaunch the best of luck. It will be quite interesting to see footage of a launch from this thing...