World's Largest Aircraft (Stratolaunch) Flies for the First Time

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MikeK

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OK, wonderful aircraft, but what is it for? OK, sorry, I went back to read the report. Actually, it's what I have always supported, flying up to space as opposed to the standard Saturn 5 type of launch. Richard Branson pioneered this system, and I'm glad to see it catching on. I would think they could fly higher than 15,000 feet before launching the spaceship, though.
Just on the fantasy side, I had imagined a hydrogen airship floating to it's maximum ceiling, then burning the hydrogen and some liquid oxygen for a final thrust upwards. Once as high as it would go, the now empty craft would somehow return to land without collapsing into a heap. I haven't figured the return out, yet. A great big empty blimp with no internal pressure isn't going to fly very well......
 
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Wanttaja

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OK, wonderful aircraft, but what is it for?
Does make me wonder, a bit. The plane was developed as the first stage of a space-launch system...carry a rocket and its payload up to 35,000 feet (past the thickest part of the atmosphere) and launch them.

However, one of the news reports today said that they're no longer developing their own rockets, they're going to use the Orbital ATK Pegasus XL.

Now, the Pegasus is a great system, I launched one of my payloads on one. But the Pegasus XL does quite nicely with an L-1011; it doesn't need a brand-new dedicated system. So what does the Stratolaunch bring to the program? Surely it'd be cheaper to convert old 747s rather than design and build a new plane?

It's possible Orbital is upgrading the Pegasus past the point where a jumbo can carry it.

And if you were referring to the He-111Z? That was designed to tow Me-321 Gigant gliders. Instead, they added motors to the gliders to produce the ME-323.

Ron Wanttaja
 

Bill-Higdon

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Does make me wonder, a bit. The plane was developed as the first stage of a space-launch system...carry a rocket and its payload up to 35,000 feet (past the thickest part of the atmosphere) and launch them.

However, one of the news reports today said that they're no longer developing their own rockets, they're going to use the Orbital ATK Pegasus XL.

Now, the Pegasus is a great system, I launched one of my payloads on one. But the Pegasus XL does quite nicely with an L-1011; it doesn't need a brand-new dedicated system. So what does the Stratolaunch bring to the program? Surely it'd be cheaper to convert old 747s rather than design and build a new plane?

It's possible Orbital is upgrading the Pegasus past the point where a jumbo can carry it.

And if you were referring to the He-111Z? That was designed to tow Me-321 Gigant gliders. Instead, they added motors to the gliders to produce the ME-323.

Ron Wanttaja
Yeap that's one I was referring to, Ernst Heinkel when asked about it after WWII said it wasn't his idea. The 321 when fitted with the surplus GR14 engines did ok as long as there wasn't any opposing aircraft to attack it
 

Victor Bravo

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I remember reading that on one of the first Me-323 Gigant cargo missions they had a large percentage of them shot down, because it was just too big and slow of a target and too easy to shoot down.
 

Marc Zeitlin

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Does make me wonder, a bit. The plane was developed as the first stage of a space-launch system...carry a rocket and its payload up to 35,000 feet (past the thickest part of the atmosphere) and launch them.

However, one of the news reports today said that they're no longer developing their own rockets, they're going to use the Orbital ATK Pegasus XL.
Having watched the development of this plane from the time I arrived at Scaled in 2005 (at which time it was already a 5 - 10 year old idea from Burt), I can say that it's currently a solution in search of a problem. Originally (and even in 2011, when I worked on it a bit and it was first funded by Paul Allen) it was envisioned as a launch mechanism that could put almost ANY payload (and read here, "big honking spy satellites for the NSA, DOD and CIA) into almost ANY orbit within 12 - 24 hours, so that any particular square inch of the planet could be examined. Of course, no one ever SAID that that was the plan, but you don't have to be Albert Einstein (or hey - a rocket engineer!) to figure out what kinds of payloads might need that kind of launch capability.

And spy satellites used to be very big and heavy - now, everything is a small cubesat - light and cheap(er). So the need to be able to haul a horizontal launch 500K lb. rocket (that hasn't been and will never be developed) is mooted.

Interestingly, everyone thinks that launching from 35K ft. is going to either save fuel, enlarge the payload, or somehow make launches easier/cheaper. None of those things is true. What is gained from being higher is lost by launching horizontally and having to make a gamma turn to go vertical. The advantage is just that you can fly to anywhere, point in any direction, and launch. Can't do that when launching from Vandenberg or Cape Canaveral. And no one was ever able to figure out how they were going to make a 500K lb. rocket make a gamma turn, and take the loads from being horizontal during the carry phase of flight.

Now, the Pegasus is a great system, I launched one of my payloads on one. But the Pegasus XL does quite nicely with an L-1011; it doesn't need a brand-new dedicated system. So what does the Stratolaunch bring to the program?
See above. Nothing.

It's an amazing accomplishment, and my friends at Scaled should be proud of it from a technical standpoint. But I'd bet a lot of $$$ that it'll make a few more flights and then end up outside at some museum forever, like the Spruce Goose (but taking up way more space).

Surely it'd be cheaper to convert old 747s rather than design and build a new plane?
Had launching Pegasus XL's been the original intent, then you're absolutely correct - modify something you've already got.
 

MikeK

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Having watched the development of this plane from the time I arrived at Scaled in 2005 (at which time it was already a 5 - 10 year old idea from Burt), I can say that it's currently a solution in search of a problem. Originally (and even in 2011, when I worked on it a bit and it was first funded by Paul Allen) it was envisioned as a launch mechanism that could put almost ANY payload (and read here, "big honking spy satellites for the NSA, DOD and CIA) into almost ANY orbit within 12 - 24 hours, so that any particular square inch of the planet could be examined. Of course, no one ever SAID that that was the plan, but you don't have to be Albert Einstein (or hey - a rocket engineer!) to figure out what kinds of payloads might need that kind of launch capability.

And spy satellites used to be very big and heavy - now, everything is a small cubesat - light and cheap(er). So the need to be able to haul a horizontal launch 500K lb. rocket (that hasn't been and will never be developed) is mooted.

Interestingly, everyone thinks that launching from 35K ft. is going to either save fuel, enlarge the payload, or somehow make launches easier/cheaper. None of those things is true. What is gained from being higher is lost by launching horizontally and having to make a gamma turn to go vertical. The advantage is just that you can fly to anywhere, point in any direction, and launch. Can't do that when launching from Vandenberg or Cape Canaveral. And no one was ever able to figure out how they were going to make a 500K lb. rocket make a gamma turn, and take the loads from being horizontal during the carry phase of flight.

See above. Nothing.

Had launching Pegasus XL's been the original intent, then you're absolutely correct - modify something you've already got.
It's an amazing accomplishment, and my friends at Scaled should be proud of it from a technical standpoint. But I'd bet a lot of $$$ that it'll make a few more flights and then end up outside at some museum forever, like the Spruce Goose (but taking up way more space).

Marc, your concern with the gamma turn doesn't make sense to me. Whenever the rockets launch vertically they have to make a turn towards the horizontal to start to gain orbital speed. The launch from the airplane is already going in that direction, and didn't burn tons of fuel to get to the first few feet off the ground. That should eliminate the usually wasted first stage. (although I am very impressed with current first stage returns!)
I think the airplane represents a first stage more dependable for re-use.
 

Marc Zeitlin

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Marc, your concern with the gamma turn doesn't make sense to me.
Are you arguing the facts, or asking for an explanation?

Whenever the rockets launch vertically they have to make a turn towards the horizontal to start to gain orbital speed.
Yes, once they are FAR higher than 35K ft. And even at hundreds of thousands of feet, they're still nowhere near horizontal.

The launch from the airplane is already going in that direction, and didn't burn tons of fuel to get to the first few feet off the ground. That should eliminate the usually wasted first stage.
If you go horizontal at 35K ft., you'll burn up in the atmosphere when you start getting up to Mach 2 - 3 and above. Since you need to get to Mach 17 to get into orbit, you won't have much of a rocket left unless you get a LOT higher before you turn horizontal. The physics, aerodynamics and orbital mechanics are well known and clear. Vertical launch rockets generally don't even reach a 45 degree angle to the vertical until they're in the 80 - 100 km altitude range - FAR higher than 35K ft.

Interestingly, one of the original thoughts (and I'm pretty sure I mentioned this in a previous thread) was to have rocket boosters in the twin booms to provide extra thrust, so that the aircraft could climb at a 45 degree angle during the launch, to eliminate 1/2 or more of the gamma turn. And that would have made a large difference in payload capacity of the rocket. However, the idea of having even liquid or hybrid motors that could theoretically be shut off go asymmetric in thrust due to a failure of some type was deemed far too risky, given the non-centerline thrust - it would essentially guarantee loss of the aircraft and crew, and the idea was discarded.

I think the airplane represents a first stage more dependable for re-use.
Had the original intent customers been able to put a satellite into the orbit they wanted to, in the timeframe they wanted to, using CC or Vandeberg as launch sites, they would have done so - the reusability of the launcher was meaningless.
 

Wanttaja

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During my aerospace career, I spent a number of years studying quick-reaction launch systems for rapid replenishment of on-orbit satellites. The Orbital Science Corporation (OSC) Pegasus was always a favorite. However, the throw weight of the Pegasus was kind of towards the bottom... not really an option if you were looking to rapidly restore existing types of spacecraft.

In the late '90s, Orbital proposed a new launch vehicle...taking a nearly stock Pegasus (without the wing) and putting it atop a surplus Minuteman first stage. Basically converting the air-launch rocket back to a "normal" ground launched system. IIRC, this was the OSC Taurus.

What was weird was that the new configuration gave a TREMENDOUS increase in the throw weight capability...IIRC, it could launch twice as much weight to the same orbit.

So much for the claim that air-launched vehicles are more efficient. Orbital eventually switched to an Mx (Peacekeeper) first stage, which gave even more launch capability. They called that version the Minotaur.

Air launched launch vehicles supposedly provide more launch flexibility...but it's almost never used. The stages generally aren't stacked until the mission is almost ready to go, and that's true for the air-launched as well as the ground-launched vehicle. I remember doing a study once where I showed that you could stack and launch a Minotaur in three days. Not much of an advantage over a Pegasus.

Nominally, you have a wider selection of launch azimuths since the aircraft can fly out to locations that have fewer limits. Practically, this is almost never done. You need range support for launches, and you end up needing a whole flying circus if you're going to try to launch outside the tracking stations used for the existing test ranges.

Similarly, you can put more weight into orbit by launching near the equator (the rotational speed of the Earth is the highest. But that's a long flight from CONUS bases, and you have to keep the rocket alive the whole time.

Ironically, Boeing does this, but with BOATS, not airplanes...the Sea Launch system. They tow a converted oil platform to the launch location, accompanied by a combination control/tracking ship.

So it'll be interesting to see if the Stratolaunch system actually provides a new capability. Without a rocket customized to take advantage of the capabilities, I don't really see much for it. The Falcon's ability to fly the stages back for re-use pretty much cancels the main advantages of an air-launched system.

To put SOME homebuilt aircraft stuff into this posting, here's a drawing of an X-37 painted up like a Fly Baby....



Ron Wanttaja
 
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bmcj

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Marc,

I thought there was already a pitch up lob plan for the jet only version of Stratolaunch, wasn’t there?

I think the best chance of success for the SL is versatility of mission capability. Orbital launch missions I think will be few and far apart, but the ability to carry a variety of loads would allow it to be used in other ways such as fire bomber, modular cargo pod carrier, or even a replacement for the Edwards test drop mothership. You could even use it for unusual or bizarre applications like citywide leaflet drops, record setting formation skydive drops, rocket section carriage, large fish repopulation drops in lakes, large scale paratrooper invasion force deployment, large sample statistical test to check the likelihood that cats will land on their feet, and shade at airshows.
 
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