Will StratoLaunch Fly?

[DDE]

20 hours ago, lysol said:

Another pro is being able to launch in bad weather on the ground.

Only if your rocket is an American-made wimp. The Buran launched in the middle of a full-fledged blizzard with no issues.

[Emperor of the Titan Squid]

i think stratolaunch will happen, but it won't work very well

[wumpus]

5 hours ago, DDE said:

Only if your rocket is an American-made wimp. The Buran launched in the middle of a full-fledged blizzard with no issues.

Which only matters for a few launch sites:

Vandenburg: does smog (and smog variations) count as weather?  I think that (and minor temperature levels) are the only thing that counts as "weather" in Southern California.

The Mojave: Two types of weather: hot and hotter.  What do you expect from a southern desert?

KSC: Two types of weather:  hot and humid, and thunderstorms.  They never should have launched the shuttle with icicles hanging off of it (no icicles in Vandenburg, either).  Complain about not launching in subtropical storms, because they are pretty common in Florida.

Wallops: I think it is the only US launch site with four seasons.  Still south of the Mason-Dixon line, so expect more hurricanes than blizzards.

[Kryten]

Bringing this thread back from the dead because Stratolaunch have finally announced what their new rocket is. Specifically it's Pegasus. Not the Pegasus II vehicle they had been developing with OrbATK, just normal Pegasus rockets as are currently flown from Orbital's L-1011.

But how, I hear you asking, can they justify using their giant carrier aircraft for Pegasus when OrATK have one that works just fine?

By launching three at once.

But how, I also hear you ask, can they fly three Pegasi (?)  at once when Pegasus now flies about once a year at best? Well... you won't get an answer for that from this release. The whole thing seems even less viable that their last two attempts to fit a launcher to this thing. It feels desperate.

[Steel]

Well that seems a shame. I really like what they were trying to achieve and the whole air-launch concept as a whole. 

My best guess would be that that their aircraft may be able to go higher(?) and faster (???) that the L1011, giving the Pegusus a little more capability? Also,I suppose if the company can stay afloat (which might be stretch, considering currently the Pegasus on the old plane has two launches planned in the next two years) this is a good way to test their aircraft with a proven rocket.

[todofwar]

After reading all this I think the Pegasus was fine for what it wanted to be, but further development doesn't seem to pay off. Now, if they can get this thing cheap enough for more academic labs to access LEO or maybe even fly by the moon, I can see some use for it. Such lower funding labs would probably not need a falcon 9 and small rockets will benefit more from air launch. But then again the falcon 9 can launch multiple satellites at once and solve the smaller satellite launch issue. 

If someone can get a hypersonic air launch at 80,000 feet to work, that might be a different story. 

[Steel]

7 minutes ago, todofwar said:

If someone can get a hypersonic air launch at 80,000 feet to work, that might be a different story. 

Very true, but considering very few people other than NASA can get hypersonic anything these days, this may be a while off

[Matuchkin]

On 21/06/2016 at 4:52 PM, wumpus said:

How much would it really cost to build a launch pad in Ecuador anyway?  Because that would do everything an airlaunch does.

Doesn't the ESA launch from Kourou? I thought that was close enough to the equator.

[Kryten]

29 minutes ago, Matuchkin said:

Doesn't the ESA launch from Kourou? I thought that was close enough to the equator.

It's 4 degrees north, which is close enough for government work. There's also a Bazilian launch base at 2 degrees south, Alcantara.

[Tex_NL]

Will it fly? Sure. Will it achieve orbit? Probably. Will it be efficient? I doubt it.
A large plane like that won't fly much higher or faster than a large commercial airliner. And even IF it flies higher I doubt it will be anything above 15km. And it will definitely be subsonic. Mach 1 at 15km is only a fraction of getting to orbit. A simple additional booster (preferably reusable like SpaceX) would do the same for less.

Edited October 7, 2016 by Tex_NL

[DerekL1963]

3 hours ago, Tex_NL said:

Will it fly? Sure. Will it achieve orbit? Probably. Will it be efficient? I doubt it.
A large plane like that won't fly much higher or faster than a large commercial airliner. And even IF it flies higher I doubt it will be anything above 15km. And it will definitely be subsonic. Mach 1 at 15km is only a fraction of getting to orbit. A simple additional booster (preferably reusable like SpaceX) would do the same for less.

They're not chasing speed or altitude.  They're chasing the theoretical benefit of not being tied to a range and of various orbital insertion parameters that come from not being tied to a fixed launch pad.

Given that Pegasus has reached orbit a number of times from a L-1011, I don't see any reason to doubt it will do so from Stratolaunch.

[magnemoe]

23 hours ago, todofwar said:

After reading all this I think the Pegasus was fine for what it wanted to be, but further development doesn't seem to pay off. Now, if they can get this thing cheap enough for more academic labs to access LEO or maybe even fly by the moon, I can see some use for it. Such lower funding labs would probably not need a falcon 9 and small rockets will benefit more from air launch. But then again the falcon 9 can launch multiple satellites at once and solve the smaller satellite launch issue. 

If someone can get a hypersonic air launch at 80,000 feet to work, that might be a different story. 

Yes, for an small launcher air launch make sense as you avoid most of the drag who is hard on small rockets and you can start with an vacuum optimized first stage. 
However unless you need an specified orbit an secondary payload slot is far cheaper. 

[Tex_NL]

2 hours ago, DerekL1963 said:

They're not chasing speed or altitude.  They're chasing the theoretical benefit of not being tied to a range and of various orbital insertion parameters that come from not being tied to a fixed launch pad.

Given that Pegasus has reached orbit a number of times from a L-1011, I don't see any reason to doubt it will do so from Stratolaunch.

What benefits are you talking about? There are no inclinations or orbits unachievable when launching at, or very close to the equator. And even then, the most efficient location to fly your carrier plane from is ... the equator. If Stratolaunch wants a nice equatorial orbit they still would have to fly their plane to the equator to launch the payload.
Sorry for being such a pragmatist but I just don't see the benefits. I don't doubt it will work. I don't doubt it can achieve its goal. I just don't believe it is the easiest and most efficient method.

Edited October 7, 2016 by Tex_NL

[DerekL1963]

4 minutes ago, Tex_NL said:

I just don't believe it is the easiest and most efficient method.

It's not.  There's a reason why Pegasus is one of the most expensive launchers per kg.
 

5 minutes ago, Tex_NL said:

What benefits are you talking about?

Mostly phasing because the "launch pad" can be at a precise spot at a precise time. (Why this is a major benefit is beyond me.)  You can also launch to an arbitrary inclination w/o having to dogleg.   Don't shoot the messenger, I'm just repeating what they've said over the years.

[Tex_NL]

1 minute ago, DerekL1963 said:

...
Mostly phasing because the "launch pad" can be at a precise spot at a precise time. (Why this is a major benefit is beyond me.)  You can also launch to an arbitrary inclination w/o having to dogleg.   Don't shoot the messenger, I'm just repeating what they've said over the years.

Yeah, OK. You will have a bit more flexibility with your launch windows. Especially when your launch site is not near the equator. But at the equator EVERY orbit at whatever inclination will line up with your launch site twice a day. If you can not delay your launch for twelve hours that is probably the least of your problems.

Don't worry. I won't shoot you for being the messenger. I know you are not the Stratolaunch spokesman. You are just the one who replied.

[Kryten]

It should probably be pointed out that there isn't really an near-equatorial launch site for small missions. The smallest thing from Kourou is Vega; it's a 'small launcher' by conventional reckoning, but it's in the 1.5-2 ton to orbit class and something like €65-70 million. Also, US government missions including NASA ones cannot legally use foreign launchers. That's why Pegasus still exists, nothing else works for small science missions with equatorial or otherwise specialised orbits. It's not exactly a big market niche, but it's there.

Edited October 7, 2016 by Kryten

[_Augustus_]

51 minutes ago, Kryten said:

US government missions including NASA ones cannot legally use foreign launchers. 

Then how is JWST launching on the Ariane V?

[Kryten]

That's technically a NASA-led international mission. Common for big projects, but adds too much bureaucratic overhead for most small missions.

[passinglurker]

7 hours ago, Kryten said:

It should probably be pointed out that there isn't really an near-equatorial launch site for small missions. The smallest thing from Kourou is Vega; it's a 'small launcher' by conventional reckoning, but it's in the 1.5-2 ton to orbit class and something like €65-70 million. Also, US government missions including NASA ones cannot legally use foreign launchers. That's why Pegasus still exists, nothing else works for small science missions with equatorial or otherwise specialised orbits. It's not exactly a big market niche, but it's there.

meaning they either have a way to drop prices to roughly 10million per pegasus or they are banking on thier proven flight record/virgin falling flat on thier face like they always do to protect thier niche.

[wumpus]

On 10/7/2016 at 3:57 PM, Tex_NL said:

Yeah, OK. You will have a bit more flexibility with your launch windows. Especially when your launch site is not near the equator. But at the equator EVERY orbit at whatever inclination will line up with your launch site twice a day. If you can not delay your launch for twelve hours that is probably the least of your problems.

Don't worry. I won't shoot you for being the messenger. I know you are not the Stratolaunch spokesman. You are just the one who replied.

Except this only makes sense if you are launching one at a time.  There's no way to finish Startolaunch and turn around and use it cheaper than the L1011 (for single launches).   For three launches, it is unbelievable that all three launches wanted that same window, nor that they couldn't be grouped on a bigger rocket cheaper.

They are looking for a sucker to invest in this thing, but probably need a better patter than this.

[Kryten]

It's worth noting that the release says that Pegasus on Stratolaunch is what the Vulcan-OrbATK partnership will lead to initially. This is likely something to make Stratolaunch avoid the stench of being a Spruce Goose for Vulcan's investors while they work on a real rocket. Something like the initial Pegasus 2 concept could be a lot more financially viable now BE-3 is available, for example.

[wumpus]

1 minute ago, Kryten said:

It's worth noting that the release says that Pegasus on Stratolaunch is what the Vulcan-OrbATK partnership will lead to initially. This is likely something to make Stratolaunch avoid the stench of being a Spruce Goose for Vulcan's investors while they work on a real rocket. Something like the initial Pegasus 2 concept could be a lot more financially viable now BE-3 is available, for example.

There still is absolutely no reason to *ever* launch a pegasus from stratolaunch.  Initial or not, it will almost certainly exist only as a paper capability (since nobody will buy it).  A pegasus2/3 might make sense, but without a real rocket (that can't be launched cheaper on L-1011) Stratolaunch and $5 gets you coffee.

[Kryten]

Aye, we're on the same page there. Having this expensive aircraft doing something on paper is better for perception than it waiting in a hangar for the new rocket, even if that's what it's doing de facto.

[Northstar1989]

On 6/22/2016 at 1:53 AM, Nibb31 said:

But nobody is proposing a Mach 3 air launch because:

• Hypersonic separation is a difficult nut to crack.
• Mach 3 and 24 000 meters still makes a rather crappy first stage (typically they get you to Mach 6 or 7 at 100 km).
• You are still going to need a pretty large multi-stage rocket with a first stage that will only be marginally smaller.
• Nobody wants the cost of developing a one-off XB-70 just to have it fly once a month or less.

Nibb, I must remind you that the Delta-V necessary to reach a given speed and altitude and the speed you travel at that altitude are two entirely different things.  It takes well over 2000 m/s to reach Mach 3 and 24 km altitude.  You also can efficiently use vacuum-optimized rocket nozzles at 24 km, which drastically increases your ISP...

 

See below:

On 6/22/2016 at 10:21 PM, Laie said:

Hey hey hey, wait a second.

From playing Realism Overhaul, I'm under the impression that it takes on the order of 1500-2000m/s just to get to Mach1@10km. That's only a fraction, but not exactly a small one. In terms of mass, that's 40-60% of the entire rocket.

In principle, small LVs suffer the most from drag, and hence should benefit the most from being carried out of the worst atmosphere. Besides, the smaller the rocket, the wider the choice of planes that could carry it to altitude. The standard example was an SDI satellite killer. Less than a hundred kg payload, but as a standalone LV it would have required MRBM-class infrastructure. Air-launched it's just another kind of missile that goes on the standard mount points.

I won't try to sell anyone on that concept for civilian launches. Especially not for 5t payloads (that's a lot). I just want to point out that air launch is not as obviously silly on the face of it as some here seem to believe.

The problem with air-launch really isn't that it doesn't make sense from a physics perspective.  It's that to really get the most out of it, you need an expensive-to-develop plane uniquely built for high altitude flight with a very heavy payload...  The R&D costs are what get you...

Besides, if you're trying to get the most out of a plane, why stop at air-launch?  It makes a lot more sense to just build a spaceplane that dolphins out of the atmosphere, and release a heavy upper-stage on a suborbital trajectory at a couple km/s of speed.  This way, you eliminate the need for a first stage entirely, while not needing to design a spaceplane that can get all the way to orbit (the difficulties of spaceplane design increase exponentially the more Delta-V it needs to carry- and the wings/ airbreathing engines don't provide any benefit once you're high enough you need to swap to rocket propulsion, they're just deadweight, and at that point Lift/Drag is likely to end up below 1...)

Of course, at that point you're probably just better off with a reusable launch stage, ala Falcon 9, unless you're using something like Microwave Beamed Power which is very limited in takeoff-thrust (and since Escape Dynamics went under, MBP probably won't happen for at least 40 years...)

 

Regards,

Northstar

Edited August 29, 2017 by Northstar1989
Spelling

[wumpus]

To try to get midway between a stratolaunch and a falcon 9, consider a rocket with a jet engine as a first stage.  It would probably require a runway like Edwards air force base and still have wing issues (your first stage would likely be elongated for aero reasons).  You would have all the landing issues of Blue Origin (throttling shouldn't be an issue) and still not even have their delta-v.  I  can't imagine how many launches you would need to justify such a stage over the cheaper and vastly more capable (if thirstier) rocket engine.  No reason to design the rest of the airplane if all you want is a rocket stage.

I'm less convinced that ground based power (such as Escape Dynamics) is completely dead.  Mostly due to US Naval projects trying to use lasers as weapons, they seem to have immense budgets (that Escape Dynamics could only dream about) to try to get power from ships to elsewhere via EM waves.

Has anybody really considered mountain launch (well, since the 1950s)?  Russia launches over land all the time, but my best two guesses had nasty range issues downstream (Leadville, CO and Cayambe, Equador).