Stratolaunch: General Company and Development Updates and Discussions

[MP99]

I thought I'd made it clear in my previous post that this is only integrating with / replacing the previously baselined RL-10 upper stage. Would still rely on the other (solid) stages, so doesn't need six RL-10s.

Cheers, Martin

[MP99]

Wow, that MAKS looks hilarious. No, not what I was picturing.

The original Stratolaunch was two solids + an RL-10 upperstage. Basically, replace the third & fourth solid stages in the new launcher with recoverable RL-10s in DC and an expendable H2 tank.

DC & ET would be supported by interstage until all the solid stages have fired and fallen away. The join between DC & ET would not need to support the tank against aero loads (the interstage would offload those stresses), only carry the weight of the tank against RL-10 g-forces in vacuum.

So, I was picturing something more akin to Shuttle + ET. Possibly even an ogive on top of the tank for aero.

Maybe even a pair of tanks nestled into / above the gaps between body and the "wings" (not sure of the correct terminology here). This would avoid having penetrations in the heatshield.

Cheers, Martin

Edit: if the H2 tanks carried the same prop load as Centaur DEC (~3t of H2 out of a ~21t prop load), this would be two cylinders ~6.7m long at 2m diameter. Or, a single tank 2.8m ID.

I'm sure this requires a much larger O2 volume than DC could accommodate, since much of the volume currently occupied by the hybrids would hold RL-10 machinery, instead.

[MP99]

But, I should have realised that the nozzles of the RL-10s would get in the way of the docking port at the back.

Cheers, Martin

[R7]

Maybe even a pair of tanks nestled into / above the gaps between body and the "wings" (not sure of the correct terminology here). This would avoid having penetrations in the heatshield.

Check Lockheed LS-200, one of countless 70s shuttle proposals.

[Rocket Science]

Maybe even a pair of tanks nestled into / above the gaps between body and the "wings" (not sure of the correct terminology here). This would avoid having penetrations in the heatshield.

Check Lockheed LS-200, one of countless 70s shuttle proposals.

Star Clipper!

[R7]

Star Clipper!

Same people behind it but slightly different. Star Clipper tanks go under the wings. LS-200 tank ends connect to topside of wings.

[Rocket Science]

Star Clipper!

Same people behind it but slightly different. Star Clipper tanks go under the wings. LS-200 tank ends connect to topside of wings.

This one had the deloyable jet engines in pods IIRC..

[Rocket Science]

Gee... I wonder where Burt got his idea for Stratolaunch?


https://fbexternal-a.akamaihd.net/safe_image.php?d=AQDJFOs3xEXXil_v&w=484&h=253&url=http%3A%2F%2Fi.kinja-img.com%2Fgawker-media%2Fimage%2Fupload%2Fs--nxDtj7z---%2Ff0948ex0guvouzznhpgn.jpg&cfs=1

[ChrisWilson68]

Do you think mini-Dream Chaser will be able to ditch in the sea in an abort situation?

[bubbagret]

Bad things happen to solids so quickly, I can't realistically see DC aborting from a solid stack safely in hardly in hardly any conceivable circumstance.

[ChrisWilson68]

Bad things happen to solids so quickly, I can't realistically see DC aborting from a solid stack safely in hardly in hardly any conceivable circumstance.

Aborts can happen for lots of reasons that don't involve the solid blowing up.  If there's loss of control, the solid will just keep burning, spiraling out of control or into the sea/ground.  You'd definitely want to be able to abort from it while the solid is burning in that case.

Orion's LAS was supposed to be able to take it safely out of range of an exploding Ares I first stage.  While outside analysis suggested it might not be able to actually do that, at least that was the plan.

At the very least, there's the case that they drop the rocket from the plane and the solid doesn't ignite for whatever reason.  You'd hope that mini-DC would be able to detatch and survive in that case.

[Space Ghost 1962]

Bad things happen to solids so quickly, I can't realistically see DC aborting from a solid stack safely in hardly in hardly any conceivable circumstance.

Aborts can happen for lots of reasons that don't involve the solid blowing up.  If there's loss of control, the solid will just keep burning, spiraling out of control or into the sea/ground.  You'd definitely want to be able to abort from it while the solid is burning in that case.

Keep in mind the acceleration profile of a solid is high. The advantage of crew air launch is that you don't need the parasitic weight of a LAS, because you turn off the booster/US, detach, and glide back - you don't have to outrun the stage to exit its potential debris field.

With a solid, you can't terminate thrust, so you have to outrun it. And, because of its acceleration, you have to out thrust it too!

Orion's LAS was supposed to be able to take it safely out of range of an exploding Ares I first stage.  While outside analysis suggested it might not be able to actually do that, at least that was the plan.

In both Ares I case and this case (unlike Shuttle), the crew vehicle is axially aligned above the booster, such that a rupture will spray high velocity burning propellant  on the crew vehicle.

The good news with this case than Ares I, is that the trajectory (before the turn) is inclined, such that a small interval LAS thrust can be used to vector away from the booster such that you are out of the debris field. The bad news is after the turn you are plastered to the booster at an even higher acceleration

At the very least, there's the case that they drop the rocket from the plane and the solid doesn't ignite for whatever reason.  You'd hope that mini-DC would be able to detatch and survive in that case.

Easy case. Also, ignition on solids is very reliable. The big risks are as the burn proceeds with a nozzle jam with propellant break off, causing overpressure and casing rupture.

It is possible to design thrust termination/cancellation ports radially around the top, such that the booster is in effect its own abort separation thruster. However this increases cost and testing issues.

[Rocket Science]

Do you think mini-Dream Chaser will be able to ditch in the sea in an abort situation?

I've only ditched the HL-20 in a sim and it handled fine. I've never seen any tank tests for DC and the flight characteristics for DC MKII should be somewhat similar though not exactly identical depending on exact weight and any aero mods...

[Danderman]

Perhaps someone has mentioned this earlier, but even if Dream Chaser could only produce 1 km/sec via its own propulsion, it would be a viable SpaceShip Two substitute, in the event that SS2 could never get to 100 km.

In other words, there is a viable market for DC + Stratolaunch, even without the Stratolaunch rocket.

[Nibb31]

Assuming there is a viable market for SS2 in the first place.

It also seems to me that Stratolauncher+DC would cost a lot more to operate than SS2.

[R7]

if Dream Chaser could only produce 1 km/sec via its own propulsion, it would be a viable SpaceShip Two substitute

DC would need a window job.

[yg1968]

This isn't a new article but it has some encourging quotes on the chances that Paul Allen will choose DC as its spacecraft.

“The whole point of Stratolaunch is to open up and really allow a fuller exploitation (of space) commercially,” said Stratolaunch executive director Charles Beames. The Dream Chaser is something like a “space Corvette,” he added. “It has Paul’s attention. He’s very excited about it.” Allen is expected to make a decision about whether to partner with Sierra Nevada before the end of the year, Beames added.

http://sen.com/news/paul-allen-s-stratolaunch-eyes-sierra-nevada-dream-chaser-space-plane

[yg1968]

It looks like Stratolaunch will opt for an all-solid LV:
http://aerosmart.com/stratolaunch-drops-liquid-stage-from-rocket-system/

[...] Gary Wentz, company CEO. The company “suspended work on the liquid variant air launch vehicle but continues to pursue an all-solid vehicle” with its contractor, Orbital Sciences Corp., he tells Aviation Week.

Stratolaunch Systems is shifting its strategy to focus its rocket system solely on solid-fuel propulsion after scrapping plans in August to consider liquid-fueled options...

http://aviationweek.com/awin-only/stratolaunch-drops-liquid-stage-rocket-system

[sdsds]

It looks like Stratolaunch will opt for an all-solid LV

So does replacing the hydrolox upper stage (with two solids) make it a four solid stage vehicle?

This was somewhat implied in the article Chris wrote recently:
http://www.nasaspaceflight.com/2014/10/dream-chaser-eyes-rides-with-under-review-stratolaunch-system/

[Lars-J]

All solid? So the already anemic Stratolauncher performance becomes even worse?