Paul Allen’s six-engine Stratolaunch

Point out news stories, on the net or in mainstream media, related to polywell fusion.

Moderators: tonybarry, MSimon

Diogenes
Posts: 6967
Joined: Mon Jun 15, 2009 3:33 pm

Paul Allen’s six-engine Stratolaunch

Post by Diogenes »

New photos reveal mammoth structure of Paul Allen’s six-engine Stratolaunch


Image


Paul Allen's giant satellite launch plane, called Stratolaunch, has been kept mostly under wraps since the project began – or at least as much under wraps as you can keep something with a 380-foot wingspan.

But now, new images from a California television station have revealed some interesting details about the aircraft.

http://www.bizjournals.com/seattle/blog ... o&page=all
‘What all the wise men promised has not happened, and what all the damned fools said would happen has come to pass.’
— Lord Melbourne —

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Re: Paul Allen’s six-engine Stratolaunch

Post by Tom Ligon »

That's a HUGE craft for Scaled Composites to build. They probably had to make special autoclaves to build it.

It would be interesting to see more specs on it, but that's twice the number of engines as OSC's old L-1011, at comparable specs. The three engines on an L-1011 produced about 50,000 to 53,000 pounds of thrust each. 747 engines are more like 45,000 pounds thrust.

But carrying capacity is unlikely to be the motivation. An L-1011 could carry something like 100 tons of payload. The main reason OSC bought theirs was to handle the wider wingspan of Pegasus II, which would not fit between the fuselage and inner engine nacelle of the B-52 they used to launch the original Pegasus (and had earlier launched X-15s). So what the heck are they really planning to launch on this thing? The wingspan and power suggest a HUGE payload, and with a purpose-built airframe they are probably making a radical departure from the Pegasus approach.

AcesHigh
Posts: 655
Joined: Wed Mar 25, 2009 3:59 am

Re: Paul Allen’s six-engine Stratolaunch

Post by AcesHigh »

Whats the use? Orbit is about speed not height. How much deltav does this thing ads?

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Re: Paul Allen’s six-engine Stratolaunch

Post by Tom Ligon »

There are a couple of benefits. That first 500 mph and 30,000 ft is expensive in terms of lift off mass and payload fraction. The jet does it on jet fuel and air, and constitutes a fully reusable, quick turnaround first stage.

Launching from jet airliner cruising altitude means you can optimize the rocket's engine nozzle for high altitude. SSTO's launching from the surface must compromise nozzle shape.

The biggest advantage, though, may be the ability to pick your air launch point. If you can fly out over the ocean, you have less problem clearing your range, you can get above clouds and weather that would scrub a surface launch, and you can use launch directions that may not be considered safe for a fixed launch site. Some of these factors are why Boeing wants to use a floating launch platform, but the aircraft launch solves more problems.

Skipjack
Posts: 6805
Joined: Sun Sep 28, 2008 2:29 pm

Re: Paul Allen’s six-engine Stratolaunch

Post by Skipjack »

I think the thing mainly has operational advantages less than performance advantages. The rocket provided by Orbital is a 3 stage solid rocket with (AFAIK) no return capability and not reuse. So the impact on Isp from the additional altitude will probably be minimal. Generally, it seems to me like the rocket itself is the weakest link of the concept. Originally, the rocket was meant to a partially reusable, liquid fueled, 2- stage design provided by SpaceX, which would have benefited a lot more from the altitude provided by the plane. Industry insiders think that SpaceX quickly realized that refitting their rockets from vertical to horizontal launch would require a major redesign. This would have probably been a major distraction for comparably little benefit to their plans so they opted out of the project.

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Re: Paul Allen’s six-engine Stratolaunch

Post by Tom Ligon »

Skipjack wrote:I think the thing mainly has operational advantages less than performance advantages. The rocket provided by Orbital is a 3 stage solid rocket with (AFAIK) no return capability and not reuse. So the impact on Isp from the additional altitude will probably be minimal. Generally, it seems to me like the rocket itself is the weakest link of the concept. Originally, the rocket was meant to a partially reusable, liquid fueled, 2- stage design provided by SpaceX, which would have benefited a lot more from the altitude provided by the plane. Industry insiders think that SpaceX quickly realized that refitting their rockets from vertical to horizontal launch would require a major redesign. This would have probably been a major distraction for comparably little benefit to their plans so they opted out of the project.
The Antares OSC lost last year, originally developed as Taurus, was never where their heart was. And based on that last launch, it would be hard to get an aircrew to launch it. They've lined up some new engines for it, but they're still Russian engines.

Their first love was Pegasus. https://en.wikipedia.org/wiki/Pegasus_%28rocket%29. I had the opportunity to work with them when they were starting out (waaay before SpaceX). I tested the bolts that hold the wings on the larger version they used with the L-1011, among other bits and pieces. Pegasus was always air-launched. However, they never could do it SSTO, and it was never large enough to carry the payloads that would make it commercially viable. It sounds to me as if this is a collaboration to make an air launch platform capable of making the original OSC concept commercially viable. Obviously, Scaled Composites has also shared this dream.

The Pegasus wiki covers the arguments for air launch, which pretty much confirms what I said, except that they apparently were launching at 40,000 ft.

I would expect they would prefer to do liquid-fueled, as it should greatly improve Isp. Their earlier solid fueled efforts probably had to do with low development costs and flight safety issues with the plane. A possible compromise might be a ramjet or solid rocket booster for a liquid fueled upper stage.

mvanwink5
Posts: 2143
Joined: Wed Jul 01, 2009 5:07 am
Location: N.C. Mountains

Re: Paul Allen’s six-engine Stratolaunch

Post by mvanwink5 »

I thought the rocket was destroyed by command, in which case the command would only be given after the launch plane was clear. Also, the launch could be over the ocean well away from anything of any worry.
Counting the days to commercial fusion. It is not that long now.

GIThruster
Posts: 4686
Joined: Tue May 25, 2010 8:17 pm

Re: Paul Allen’s six-engine Stratolaunch

Post by GIThruster »

There is also the thing that Rutan gets to build his Really Big Plane. That might be the biggest reason for all of this. For smaller launches, Gary Hudson's AirLaunch and the new Firefly both seem better choices. For bigger launches, I don't see how they can compete with SpaceX once they're reusing even just the first stage.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Re: Paul Allen’s six-engine Stratolaunch

Post by Tom Ligon »

GIThruster wrote:There is also the thing that Rutan gets to build his Really Big Plane. That might be the biggest reason for all of this. For smaller launches, Gary Hudson's AirLaunch and the new Firefly both seem better choices. For bigger launches, I don't see how they can compete with SpaceX once they're reusing even just the first stage.
I don't know if they can compete either, but I'm glad to see them try. Back when I was at Meloy Labs, one of the businesspeople there explained something about competition: if you don't have any competition, that's a bad sign, because you're in a market nobody wants to touch, and you're probably doomed. The fact that others want to compete with SpaceX is highly encouraging. I'd argue that, in fact, SpaceX entered the market following in the footsteps of OSC and other small rocket outfits that saw private space launch as promising.

At a private space launch conference a few years back, there was some discussion about market. At the time, we had two satellite broadcast companies, Sirius and XM. The speaker was talking to someone at one of these companies, when that someone referred to satellite broadcast as a "market" for launch services. The speaker pointed out that two companies do not constitute a "market" for satellite launches. And, indeed, today if you want satellite radio in your car, you subscribe to SiriusXM.

One hopes that we do indeed wind up with a market for launch services that can support multiple launch companies. At the moment we're trying to clear up a huge backlog of container ships. Now that's commerce! What we want is people worrying about how the heck are we going to launch all the spacecraft we need and land all the unobtainium. We want rockets painted in the colors of dozens of competing major carriers. Right now we are not carrying enough cargo to space to impress a Greek ship owner from two and a half millennia ago.

I think we'll reach that level, but let's hope it does not take another two and a half millennia.

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Re: Paul Allen’s six-engine Stratolaunch

Post by Tom Ligon »

mvanwink5 wrote:I thought the rocket was destroyed by command, in which case the command would only be given after the launch plane was clear. Also, the launch could be over the ocean well away from anything of any worry.
And that's the downside of air launch. You drop the rocket, then light it off. If there's a problem with it, the computer can't just abort the launch and shut it down to be repaired ... gravity is in control and the bird with its payload become an expensive hole in the ocean. You have the choice of one big splash or a lot of little ones.

There have been rockets that exploded on the pad, though. It is rare these days. Somebody pushed the destruct button on that Antares but I think it was a flaming bunch of flying scrap before that, and the goal was to be sure it didn't go far. If you did start ignition while still on or very close to the plane, such a launch could be a disaster for the aircraft. No doubt one can engineer around this but it is a significant departure from our present practice of keeping people 2-3 miles away from a launch.

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Re: Paul Allen’s six-engine Stratolaunch

Post by hanelyp »

One advantage of air launch if you want stage reuse, launch from the right point and the first rocket stage has free return to near the home airfield.
The daylight is uncomfortably bright for eyes so long in the dark.

GIThruster
Posts: 4686
Joined: Tue May 25, 2010 8:17 pm

Re: Paul Allen’s six-engine Stratolaunch

Post by GIThruster »

Tom Ligon wrote:There have been rockets that exploded on the pad, though. It is rare these days.
I haven't heard much from Boeing's SeaLaunch since they blew up a Zenit on the pad. Not sure they ever sprang back.

You'd think people would stop using those ancient Russian motors.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

KitemanSA
Posts: 6179
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Re: Paul Allen’s six-engine Stratolaunch

Post by KitemanSA »

I wonder if this can be augmented with a kite-launch stage?

Skipjack
Posts: 6805
Joined: Sun Sep 28, 2008 2:29 pm

Re: Paul Allen’s six-engine Stratolaunch

Post by Skipjack »

hanelyp wrote:One advantage of air launch if you want stage reuse, launch from the right point and the first rocket stage has free return to near the home airfield.
What's the point of that with a 3 stage solid? Even if the first stage (of 3!) could be recovered, solid rocket boosters are difficult to refill so it does not really safe any money to recover them. Recovering the shuttle SRBs pretty much saved nothing. The Europeans don't even bother with the Ariane V boosters.

alexjrgreen
Posts: 815
Joined: Thu Nov 13, 2008 4:03 pm
Location: UK

Re: Paul Allen’s six-engine Stratolaunch

Post by alexjrgreen »

KitemanSA wrote:I wonder if this can be augmented with a kite-launch stage?
Cool idea...
Ars artis est celare artem.

Post Reply