Stratolaunch: General Company and Development Updates and Discussions

[baldusi]

Their renders did showed a SpaceX's standard fairing of 5.2m. If they can lengthen proportionally, a 5.2m core has 3 times the volume of a 3.65m, one.

Now you suggest making the rocket even longer than it is currently rendered.  I continue to struggle with acceptance of the idea of hanging a long, skinny rocket from its middle, without seeing what the hanging structure looks like.  The additional mass needed is ameliorated some what by the prospect of launching it from such an altitude, but the only information there is to go on is an illustration on a website.

May be I didn't express myself correctly. (5.2/3.65)^3 is pretty close to 3. In other words, the rocket would be longer, but also wider. And it might be longer, but it would also be less dense. So it's quite probable that the bending moment from the own mass would be lower, proportionally. And if you take the mass cap, and put two J-2X it's sort of a shoe in. Put an RL10 on the US and you have a pretty nice combo. Those are existing or as close to existing engines as you can get anywhere. And they would probably have better performance for LEO, and significantly better performance to high energy orbits.
I'm not stating anything about the business advantages of any of this. I'm just stating that H2 in the Stratolauncher is quite doable and even with good performance, and can be done with existing tooling and parts.
I'm not stating it would be worth the development cost, nor that it would be the fastest nor the cheapest option. Probably the higher performance, though. But we've already stated that the reason of being of Stratolauncher is cost, not performance.

[simonbp]

OK guys, let's make a few things clear:

1) SOFIA uses a 747SP because they need the range; the typical operational profile is to take off from Palmdale and "chase the Sun" going West, with a landing in Hawaii or New Zealand. That's massively more range than Stratolaunch needs, and puts lots of extra constraints on aircraft.

2) For a large telescope like SOFIA, the primary mirror _must_ be open to the sky, and _must_ have a clear line of sight. Without seriously modifying the aircraft, that's going to restrict you to objects at greater than about 60 deg elevation, which is only a very small section of the sky.

3) Vibration is a killer for all optics, especially movable ones. The end of a Stratolaunch cargo pod is going to vibrating around all over the place from aero loads. That would then require a superstiff (read heavy) pod structure and connection to the aircraft. Stiffening up SOFIA after they cut a hole in it was the most expensive and time-consuming part of the conversion.

So, while technically possible, putting a telescope in a Stratolaunch cargo pod is not really practical.

[go4mars]

1) SOFIA uses a 747SP because they need the range; the typical operational profile is to take off from Palmdale and "chase the Sun" going West, with a landing in Hawaii or New Zealand. That's massively more range than Stratolaunch needs, and puts lots of extra constraints on aircraft.

Having far larger mirrors means the same or better images can be collected in less time.  So range is not a big issue. 

2) For a large telescope like SOFIA, the primary mirror _must_ be open to the sky, and _must_ have a clear line of sight. Without seriously modifying the aircraft, that's going to restrict you to objects at greater than about 60 deg elevation, which is only a very small section of the sky.

I don't understand your concern here.  The world is round so if your mirror can't tilt much you can fly to the part of the world that faces your target galaxy or whatever.  Also, the aircraft doesn't get modified for this.  This would be an aerodynamic telescope that clips into the hanger between the fuselages.  No modifcations to the stratolaunch aircraft would be needed or desireable.  Potentially, you could design it so the mirror(s) could swivel, even pointing down if needed (though a minimal degree of tilting for just enough capability to track objects for the duration of your flight would probably be simplest). 

3) Vibration is a killer for all optics, especially movable ones. The end of a Stratolaunch cargo pod ... would then require a superstiff (read heavy) pod structure and connection to the aircraft.

Fortunately, 500000 pounds of mass should be able to fix the issue (with margin).  SOFIA's mirror weighs 880 kg.  SOFIA in total weighs about 20000 kg.   

http://www.sofia.usra.edu/Science/telescope/sci_tele_character.html

So, while technically possible, putting a telescope in a Stratolaunch cargo pod is not really practical.

Why not?  Assuming that an aircraft like stratolaunch will exist, and will work, and could be purchased or leased or copied, then I don't understand what the show-stopper would be.  If a 900 square meter stratospheric telescope could be developed for a Gigadollar or so (using KISS wherever possible), I would view that as a positive development.  Right now the wolrd's largest telescope is 84 square meters (74 effective). 

[as58]

[

So, while technically possible, putting a telescope in a Stratolaunch cargo pod is not really practical.

Why not?  Assuming that an aircraft like stratolaunch will exist, and will work, and could be purchased or leased or copied, then I don't understand what the show-stopper would be.  If a 900 square meter stratospheric telescope could be developed for a Gigadollar or so (using KISS wherever possible), I would view that as a positive development.  Right now the wolrd's largest telescope is 84 square meters (74 effective). 

Do you have any sources for your claims about how well suited Stratolaunch carrier would be for a airborne telescope? I don't know much about astronomical instrumentation, but to me your claims sound more than a bit fantastical.

[Zed_Noir]

Stratolaunch could stargaze all night, pull in to the hanger, unclip its telescope, then clip on a rocket for its morning excursion.

No, on the last line

If "roll-out to launch in <60 minutes" is a possibility for F9, then I don't see why this isn't. 

It isn't attaching the rocket to launch in <60 minutes

Have to agree with Jim. Aircraft the size and complexity of the Stratolaunch carrier requires many manhours of maintenance between flights. Something similar would be a C5 Galaxy fully loaded on a maximum range roundtrip mission.

[Comga]

Stratolaunch could stargaze all night, pull in to the hanger, unclip its telescope, then clip on a rocket for its morning excursion.

No, on the last line

If "roll-out to launch in <60 minutes" is a possibility for F9, then I don't see why this isn't. 

It isn't attaching the rocket to launch in <60 minutes

Have to agree with Jim. Aircraft the size and complexity of the Stratolaunch carrier requires many manhours of maintenance between flights. Something similar would be a C5 Galaxy fully loaded on a maximum range roundtrip mission.

While I don't want to be seen a supporting wild ideas, these are objections to a silly and inconsequential aspect of the post.  How about the rational objections to this if the changeover from observatory to launcher were allowed a week?   Justifying a megaplane launcher presupposes a significant launch rate, but capturing more than a launch every month would require some new market that isn't obvious, at least to me. 

So, if the plane is idle for 2-4 weeks at a time, what other technical objections remain, other than "been there, done that, can't even afford to buy the tee-shirt."

[Zed_Noir]

Stratolaunch could stargaze all night, pull in to the hanger, unclip its telescope, then clip on a rocket for its morning excursion.

No, on the last line

If "roll-out to launch in <60 minutes" is a possibility for F9, then I don't see why this isn't. 

It isn't attaching the rocket to launch in <60 minutes

Have to agree with Jim. Aircraft the size and complexity of the Stratolaunch carrier requires many manhours of maintenance between flights. Something similar would be a C5 Galaxy fully loaded on a maximum range roundtrip mission.

While I don't want to be seen a supporting wild ideas, these are objections to a silly and inconsequential aspect of the post.  How about the rational objections to this if the changeover from observatory to launcher were allowed a week?   Justifying a megaplane launcher presupposes a significant launch rate, but capturing more than a launch every month would require some new market that isn't obvious, at least to me. 

So, if the plane is idle for 2-4 weeks at a time, what other technical objections remain, other than "been there, done that, can't even afford to buy the tee-shirt."

Think you misunderstood my point, also maybe Jim's too. I don't think you can turnaround the Stratolaunch carrier like an airliner within a hour.

The plane turnaround downtime between missions would be roughly as short as several hours. It depends on how much monitoring instrumentation is installed on the plane.

[Comga]

While I don't want to be seen a supporting wild ideas, these are objections to a silly and inconsequential aspect of the post.  How about the rational objections to this if the changeover from observatory to launcher were allowed a week?   Justifying a megaplane launcher presupposes a significant launch rate, but capturing more than a launch every month would require some new market that isn't obvious, at least to me. 

So, if the plane is idle for 2-4 weeks at a time, what other technical objections remain, other than "been there, done that, can't even afford to buy the tee-shirt."

Think you misunderstood my point, also maybe Jim's too. I don't think you can turnaround the Stratolaunch carrier like an airliner within a hour.

The plane turnaround downtime between missions would be roughly as short as several hours. It depends on how much monitoring instrumentation is installed on the plane.

I did not miss your point, but you may have missed mine.  You and Jim are (as ususal) correct that a one hour conversion is nowhere near possible.  My point was, given this reason to ignore that small part of the original post, which other reasons are fatal to the idea of using the Stratolaunch carrier aircraft as a host for a SOFIA successor?

[Danderman]

While I don't want to be seen a supporting wild ideas, these are objections to a silly and inconsequential aspect of the post.  How about the rational objections to this if the changeover from observatory to launcher were allowed a week?   Justifying a megaplane launcher presupposes a significant launch rate, but capturing more than a launch every month would require some new market that isn't obvious, at least to me. 

So, if the plane is idle for 2-4 weeks at a time, what other technical objections remain, other than "been there, done that, can't even afford to buy the tee-shirt."

Think you misunderstood my point, also maybe Jim's too. I don't think you can turnaround the Stratolaunch carrier like an airliner within a hour.

The plane turnaround downtime between missions would be roughly as short as several hours. It depends on how much monitoring instrumentation is installed on the plane.

I did not miss your point, but you may have missed mine.  You and Jim are (as ususal) correct that a one hour conversion is nowhere near possible.  My point was, given this reason to ignore that small part of the original post, which other reasons are fatal to the idea of using the Stratolaunch carrier aircraft as a host for a SOFIA successor?

I am sure that the Stratolaunch carrier aircraft will be used as a cargo vehicle for many potential customers when it is not busy flying space missions.  However, it must be realized that its not a magic carpet, and significant work will have to be performed to adapt the aircraft to other customers. Its possible that some sort of container structure could be built for a flying telescope that would be compatible with Stratolaunch, but the problem is that Stratolaunch may not be able to provide a very long flying time, which telescopes need.  Also, its not clear if people can transfer from the main hull into a flown container, which may be a requirement for a telescope.

[as58]

I did not miss your point, but you may have missed mine.  You and Jim are (as ususal) correct that a one hour conversion is nowhere near possible.  My point was, given this reason to ignore that small part of the original post, which other reasons are fatal to the idea of using the Stratolaunch carrier aircraft as a host for a SOFIA successor?

I completely agree that a very fast turnaround wouldn't be necessary. As I've said, I'm no expert, but I just don't see why the Stratolaunch carrier would be a particularly good choice. Would it really be that much easier than using a standard aircraft? I particular, go4mars's proposals seem to me like pure fantasy. I really, really, doubt you could build a 6x8 m or 2x24 metre telescopes that could carried on the Stratolauncher even if given all the money in the world. Even one 8 m telescope would be hard enough to build with the given mass constraints. And suppressing vibration enough to get good perfomance (e.g., diffraction limited imaging) seems like a herculean effort.

I seem to remember that you wrote somewhere that you've worked on HST and (or?) JWST, so you probably know a lot more about this than I do.

[hop]

Having far larger mirrors means the same or better images can be collected in less time.  So range is not a big issue. 

You lose much of the advantage of the big mirror then. It will also drive up your observing costs, since you have to turn around a flight for much less time in the air.

Another unique capability SOFIA has is observing things that are only visible from limited areas, like KBO and asteroid occultations. This requires range, especially if your carrier can only work out of a few airports.

I don't understand your concern here.  The world is round so if your mirror can't tilt much you can fly to the part of the world that faces your target galaxy or whatever.

Limited elevation range limits what you can observe and how long you can observe it. Flying to a different location won't help if the sun is up when the object is at an elevation you can observe. This strategy would also seem to negate the idea the carrier doesn't need long range.

Also, the aircraft doesn't get modified for this.  This would be an aerodynamic telescope that clips into the hanger between the fuselages.

If the telescope is sitting between the two fuselages of the Stratolaunch carrier, you have a limited range of directions you can point. Facing forward is presumably out of the question, so you have to look up or possibly back between the fuselages. The container stills needs a large opening in it, plays havoc with aerodynamics no matter how you cut it.

Anyway, you ignoring the big picture here. There is no demand for a SOFIA successor, nor anyone working one. Big telescope projects take many years from concept to first light. By the time  (if ever) anyone starts working seriously on a SOFIA successor, Stratolaunch will be old news. Even if the Stratolaunch carrier would be a good choice today, there's no saying what will be available by then.

The signal-to-noise of this forum would be greatly improved if people didn't spend so much time using threads about real stuff as a place to argue for pie-in-the-sky concepts that are only tenuously connected to the main topic.

[go4mars]

Do you have any sources for your claims about how well suited Stratolaunch carrier would be for a airborne telescope?

No.  But if you find some, please let me know. 

go4mars's proposals seem to me like pure fantasy. I really, really, doubt you could build a 6x8 m or 2x24 metre telescopes that could carried on the Stratolauncher even if given all the money in the world. Even one 8 m telescope would be hard enough to build with the given mass constraints.

Seems like fantasy based on what?  Why wouldn't it be possible?  Mass constraints?  Even dead mass of half a million pounds helps resist vibrations, but systems and software developed for SOFIA could be implemented.  SOFIA total mass = 20Mg. 

This requires range, especially if your carrier can only work out of a few airports.

That's a good point.  Regarding range, we don't know what it's final range will really be, and we don't know how heavy the telescope would really be.   

If the telescope is sitting between the two fuselages of the Stratolaunch carrier, you have a limited range of directions you can point. Facing forward is presumably out of the question, so you have to look up or possibly back between the fuselages. The container stills needs a large opening in it, plays havoc with aerodynamics no matter how you cut it.

Picturing it like the operculum on fenestral bryozoans, like Cheilostomata.  A Frontal lip for the wind keeps the opening lid/flap out of the turbulent airstream for the front one and back.  They wouldn't necessarily have to point only backwards. 

[go4mars]

Big telescope projects take many years from concept to first light. By the time  (if ever) anyone starts working seriously on a SOFIA successor, Stratolaunch will be old news. Even if the Stratolaunch carrier would be a good choice today, there's no saying what will be available by then.

Why do anything that's uncertain?

The signal-to-noise of this forum would be greatly improved if people didn't spend so much time using threads about real stuff as a place to argue for pie-in-the-sky concepts that are only tenuously connected to the main topic.

I made one post suggesting the possibility.  If I suspected it would snowball I would have started a new thread.   

[Comga]

Picturing it like the operculum on fenestral bryozoans, like Cheilostomata. 

Surely you jest! "perculum on fenestral bryozoans, like Cheilostomata"  without so much as a wink or a link? 

[go4mars]

Picturing it like the operculum on fenestral bryozoans, like Cheilostomata. 

Surely you jest! "operculum on fenestral bryozoans, like Cheilostomata"  without so much as a wink or a link? 

Apologies.  I blame extreme sleep deprivation combined with having to suddenly rush off to something.  Had a period about a decade ago where I was keenly interested in invertebrate paleobiology and biomimicry has always been an interest.  Haven't found much with google image search.  Sorry.

Best I could find: http://www.ucmp.berkeley.edu/bryozoa/bryozoamm.html
http://en.wikipedia.org/wiki/Operculum_(bryozoa)

[chrisking0997]

hypothetical thread is hypothetical

I think Stratolaunch is going to have a hard enough time trying to figure out how to be successful launching rockets without people trying to strap on airborne telescopes or giant pony carriers or whatever else we pull out of our...heads to it.

[go4mars]

LOX-hydrogen at the full payload capability of the aircraft will fit fine; there is an S-IVB worth of diameter available so the overall length for the stage is only about 60-80 feet.  It was one of the early options for which I did a design for a previous version of the a/c about five years ago.  I wanted to go with a one-stage expendable SSTO approach but that turned out to be a bit radical for my colleagues

If you are allowed to say... Was your proposal intended to double as a F-X diameter upper stage called "raptor"? 

[HMXHMX]

LOX-hydrogen at the full payload capability of the aircraft will fit fine; there is an S-IVB worth of diameter available so the overall length for the stage is only about 60-80 feet.  It was one of the early options for which I did a design for a previous version of the a/c about five years ago.  I wanted to go with a one-stage expendable SSTO approach but that turned out to be a bit radical for my colleagues

If you are allowed to say... Was your proposal intended to double as a F-X diameter upper stage called "raptor"? 

No, had nothing to do with SpaceX or Raptor.  I can't say more about it.

[JohnFornaro]

While I don't want to be seen a supporting wild ideas, these are objections to a silly and inconsequential aspect of the post.  How about the rational objections to this if the changeover from observatory to launcher were allowed a week?   Justifying a megaplane launcher presupposes a significant launch rate, but capturing more than a launch every month would require some new market that isn't obvious, at least to me. 

So, if the plane is idle for 2-4 weeks at a time, what other technical objections remain, other than "been there, done that, can't even afford to buy the tee-shirt."

... I don't think you can turnaround the Stratolaunch carrier like an airliner within a hour.

The plane turnaround downtime between missions would be roughly as short as several hours. It depends ...

...  You and Jim are (as ususal) correct that a one hour conversion is nowhere near possible.  My point was, ... which other reasons are fatal to the idea of using the Stratolaunch carrier aircraft as a host for a SOFIA successor?

You all realize that discussing the turnaround time of an airplane which is only an image on a website has little practical application?

Then there's this:

There is no demand for a SOFIA successor, nor anyone working one.

However, if the point of the SOFIA discussion is to practice typing, then that's fine.  And speaking of typing, is it too much trouble to type the phrase "perculum on fenestral bryozoans, like Cheilostomata" into the internets?

... without people trying to strap on airborne telescopes or giant pony carriers or whatever else we pull out of our...heads to it.

Hold on there pardner.  What's wrong with ponies?  You sound like a typical nerfherder.

The most salient objection to this scheme is why isn't the angel investor bringing the inventor's proven, sub-scale RLV scheme to the proper and needed scale?

[go4mars]

The most salient objection to this scheme is why isn't the angel investor bringing the inventor's proven, sub-scale RLV scheme to the proper and needed scale?

Are you talking about something Rutan came up with?  Musk?  A different inventor?  Do you mean a bigger spaceship2? 



Just to compete the geology nerdnition:  It's "operculum".  "An operculum (on an animal) is an anatomical feature, a stiff structure resembling a lid or a door that opens and closes, and thus controls contact between the outside world and an internal part of an animal. Example:

An operculum (gastropod), a single lid that (in its most complete form) closes the aperture of the shell when the animal is retracted, and thus protects the internal soft parts of the animal that are not completely covered by the shell. The operculum lies on the top rear part of the foot. When the foot is retracted, the operculum is rotated 180° and closes the shell."

In context, it saves me from making a drawing by showing the shape (fenestral bryozoans).  Lids would probably slide in toward the middle wing. 

But that doesn't matter.  This discussion of a SOFIA successor has snowballed completely out of proportion and is becoming distracting.  I propose further discussion of it be on a new thread if it must be examined further.  Start one if you must. 

I said something along the lines of "A SOFIA successor would be possible if stratolaunch existed", and got all kinds of "no it wouldn't", or "it wouldn't be worth it", or "where is the funding coming from", or "there are better alternatives", "how exactly would it work", "do you have supporting literature/studies",  "how is a stratospheric telescope better than ground based or space based", "could you draw an exact diagram of the optics stabilization mechanism", "have you done wind tunnel studies", "what would its exact weight be", "what is its exact operational range", "which routes and runways would work best for various celestial regions", "what is the idealized cruising altitude", "what would it be called", "what color should it be painted",etc. etc. etc. 

The exact details of how it would be done are a red herring.  But I think it's a valid point that it could technically be done in some form that is larger than SOFIA, and there might be some improvements in design and/or cost drawn from SOFIA.  I'm happy to leave it at that.