Stratolaunch: General Company and Development Updates and Discussions

[Kabloona]

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

But that's what makes sense. The advantage of air launch is flexibility/simple logistics which is negated when liquids are added to the mix.

Once you've committed to solids for the lower stages you've already lost a big chunk of performance relative to liquids, and using a liquid upper stage isn't going to make up that loss up anyway, and it cripples your ground ops, so you end up with the worst of both worlds. Maybe they just figured that out. Perhaps Orbital convinced them.

[Llian Rhydderch]

This launch vehicle design has moved a great deal from what it was when Paul Allen first agreed to fund the beast.

 - Was originally liquid/liquid "Falcon 9 Air" launch vehicle concept from SpaceX
 - Changed to solid/liquid "Pegasus 2" concept from Orbital
 - and now is an all-solid Orbital Pegasus 2 concept. 

I know Allen understands the sunk cost fallacy, and he's already in hip deep on the design and build of the carrier aircraft...

But I wonder if he would invest again today, from scratch, knowing what we all know now that we didn't know then?

[RanulfC]

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

But that's what makes sense. The advantage of air launch is flexibility/simple logistics which is negated when liquids are added to the mix.

The former is right but "simple logistics" is part of the design process not anything that is inherent for air-launch. Liquids CAN be as "simple" as solids if you go the right way, and they can also be dreadfully more complex and operationally a PITB if you're not careful. Solids "biggest" advantage has always been a far more robust and "solid" (pardon the pun) structure for air-launch but at a very high "cost" in efficiency. Your "average" solid will tend towards ISPs in the low 300s while a good liquid stage will be in the mid-to-high 300s and higher but need heavier structures to "allow" for carry and launch in a horizontal position.

LOX/RP1 is pretty easy to handle and would have a higher average ISP though again you'd need a good structure to allow it to be carried and launched like that but its not something that hasn't been looked into a lot. (Frankly carrying a HTP/Kero rocket would seem to be more efficient than going all solid but its Orbital we're talking about )

Once you've committed to solids for the lower stages you've already lost a big chunk of performance relative to liquids, and using a liquid upper stage isn't going to make up that loss up anyway, and it cripples your ground ops, so you end up with the worst of both worlds. Maybe they just figured that out. Perhaps Orbital convinced them.

Since they chose Orbital to build their rocket I've been expecting this outcome actually I don't agree with it at all but then again:
1) I'm not an investor so I don't get a vote
2) They didn't ask my opinion but I give it away anyway

--This is going to mean that no in-flight propellant conditioning equipment or tanked propellants are going to have to carried by the StratoLaunch carrier aircraft which is probably a good thing. (However I'd point out you wouldn't have that issue with H2O2/kerosene either and better performance )

--This means less overall issues with integration of the LV onto the aircraft and less need for "beefing-up" the LV structure to handle the loading. (However that's not as much or an issue if you design the liquid stage right AND/OR use a low-impact carry/release mechanism, which I'd lean towards the AirLaunch system HOWEVER they have always seemed to disregard that method in favor of the "winged-LV-powered-pull-up" maneuver which again, is no surprise really. It's Orbital )

--I'm going to suspect that this is going to be a payload hit. (As the article itself seems behind a paywall I guess I'll have to wait and see) I think this will be an end to the idea that DC-Junior rides on StratoLaunch unfortunately

Randy

[Lee Jay]

I'm looking at payload fraction.  I note the following:

Pegasus XL:  1.9%
Falcon 9 1.1:  2.6%

If this is a four stage, and a larger one, and a more modern design, am I crazy in suspecting that it will do a little better in payload fraction than Pegasus XL does?  If so, it seems it might do somewhere close to Falcon 9 1.1 with the nominal 30% knockdown for return of the first stage.

That doesn't seem so bad to me.

[Lars-J]

I'm looking at payload fraction.  I note the following:

Pegasus XL:  1.9%
Falcon 9 1.1:  2.6%

If this is a four stage, and a larger one, and a more modern design, am I crazy in suspecting that it will do a little better in payload fraction than Pegasus XL does?  If so, it seems it might do somewhere close to Falcon 9 1.1 with the nominal 30% knockdown for return of the first stage.

That doesn't seem so bad to me.

Yes, but it is still 4 stages. Four. Five if you count the aircraft as a stage. Compared to a two stage LV. Now what seems simpler again?

[Kabloona]

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

But that's what makes sense. The advantage of air launch is flexibility/simple logistics which is negated when liquids are added to the mix.

The former is right but "simple logistics" is part of the design process not anything that is inherent for air-launch. Liquids CAN be as "simple" as solids if you go the right way, and they can also be dreadfully more complex and operationally a PITB if you're not careful.

We're talking about cryo upper stage here, to be specific. Yes, Pegasus had a hydrazine PIK/HAPS for some missions, but we're not talking about 100 lbs of storable hydrazine. The plan was for a ginormous cryo upper stage for Pegasus II, and that would have been a ground ops nightmare.

[Lee Jay]

I'm looking at payload fraction.  I note the following:

Pegasus XL:  1.9%
Falcon 9 1.1:  2.6%

If this is a four stage, and a larger one, and a more modern design, am I crazy in suspecting that it will do a little better in payload fraction than Pegasus XL does?  If so, it seems it might do somewhere close to Falcon 9 1.1 with the nominal 30% knockdown for return of the first stage.

That doesn't seem so bad to me.

Yes, but it is still 4 stages. Four. Five if you count the aircraft as a stage. Compared to a two stage LV. Now what seems simpler again?

I didn't mention simplicity or reliability, just performance.

[Elmar Moelzer]

I don't understand how this is ever going to be cost competitive with F9. The only way I see Stratolaunch being of any relevance is by allowing for a more responsive launch from a wide range of launch sites. Whether that is enough to warrant the effort remains to be seen.

[Todd Martin]

Switching to an all solid LV for Strato-launch will likely increase the weight of the LV.  As an example of the effect of a change in gross weight, a 21 percent increase in takeoff weight will require a 10 percent increase in liftoff speed to support the greater weight.  To compensate for the increased weight, perhaps Stratolaunch will consider making changes to accommodate a higher liftoff speed.  Some ideas are a longer runway, towing the plane during take-off, adding a rocket assist for take-off, or ending the runway off a cliff...

[Lars-J]

To compensate for the increased weight, perhaps Stratolaunch will consider making changes to accommodate a higher liftoff speed.  Some ideas are a longer runway, towing the plane during take-off, adding a rocket assist for take-off, or ending the runway off a cliff...

That would be very amusing to see. 

[edkyle99]

Switching to an all solid LV for Strato-launch will likely increase the weight of the LV.

The air launch method limits the gross weight of the rocket, no matter what type of propellant is used or how many stages are used.  If the original three-stage rocket was already near the limit, the new four (plus?) stage rocket won't weigh any more.

 - Ed Kyle

[Zed_Noir]

Switching to an all solid LV for Strato-launch will likely increase the weight of the LV.  As an example of the effect of a change in gross weight, a 21 percent increase in takeoff weight will require a 10 percent increase in liftoff speed to support the greater weight.  To compensate for the increased weight, perhaps Stratolaunch will consider making changes to accommodate a higher liftoff speed.  Some ideas are a longer runway, towing the plane during take-off, adding a rocket assist for take-off, or ending the runway off a cliff...

Or get some 777 size turbofan engines instead of the current 747 size turbofan engines. About roughly 40% increase in thrust.

[Elmar Moelzer]

Or get some 777 size turbofan engines instead of the current 747 size turbofan engines. About roughly 40% increase in thrust.

Would the structure support those?

[meekGee]

Some ideas are a longer runway, towing the plane during take-off, adding a rocket assist for take-off, or ending the runway off a cliff...

Air air launch!

[apollolanding]

Have you ever witnessed JATO/RATO?  I have and let me tell ya, the stresses on a beast like a C-130 or (before my time a B-47) are/were incredible.  Wow... I don't think the airframe for something like the mammoth carrier aircraft could handle that.  The cliff... just a longer way down before "controlled/uncontrolled flight into terrain".  You need runway length and smooth, steady assisted acceleration.  If the airframe could handle the 777 fans that would make sense but this seems like a solution looking for a problem. 

[R7]

You can always make the carrier plane to take off without the rocket, pick up speed and do a fast low level pass over electromagnetic catapult launching the rocket just in time for mid-flight hook up. No? Why not?!

[yg1968]

I don't understand how this is ever going to be cost competitive with F9. The only way I see Stratolaunch being of any relevance is by allowing for a more responsive launch from a wide range of launch sites. Whether that is enough to warrant the effort remains to be seen.

I suspect that their launch prices will be similar to those of SpaceX. So if your payload is small enough (13,500 pounds or less), you wouldn't be paying more than if you were launching on a F9. But I think that launch flexibility is the key for them. A quicker turn around than their competitor would be their best selling point.

[ChrisWilson68]

I don't understand how this is ever going to be cost competitive with F9. The only way I see Stratolaunch being of any relevance is by allowing for a more responsive launch from a wide range of launch sites. Whether that is enough to warrant the effort remains to be seen.

I suspect that their launch prices will be similar to those of SpaceX. So if your payload is small enough (13,500 pounds or less), you wouldn't be paying more than if you were launching on a F9. But I think that launch flexibility is the key for them. A quicker turn around than their competitor would be their best selling point.

I can't see how Stratolaunch could have a launch price similar to SpaceX.  They're both doing reusable first stages, but SpaceX's first stage gives so much more delta-V that they only need one more stage and it can be cheap.  Stratolaunch needs two more stages, and from what they've said they sound much more expensive than the Falcon upper stage.

Stratolaunch will need to make both their first stage (the huge carrier aircraft) and their next stage reusable to compete, but that will be a much more complex system than the Falcon 9 first stage.  How could that combination be less expensive to operate than the SpaceX Falcon 9 first stage?

[yg1968]

I meant that Stratolaunch would have to be competitive with SpaceX's current prices ($61.2M). Reusability is supposed to give you a 25% discount according to Musk (see September 6 2013 SN article) which would mean $45.9M for a flight on a reused F9. 

[ChrisWilson68]

I meant that Stratolaunch would have to be competitive with SpaceX's current prices ($61.2M).

By the time Stratolaunch first flies, SpaceX should already be flying reused first stages.  So aiming for being cost-competitive with SpaceX's current prices is betting that SpaceX will fail.  That hasn't worked out so well for SpaceX's competition so far.

Reusability is supposed to give you a 25% discount according to Musk (see September 6 2013 SN article) which would mean $45.9M for a flight on a reused F9.

Both Musk and Shotwell have given numbers that are all over the map for reusability.  They've said 25% discount.  They've said 35% discount.  They've said 75% of the cost is in the first stage, implying a 75% cost savings.  They've talked about having a goal of $7-$10 million for a F9 launch.

Once SpaceX can reuse first stages, their own marginal costs drop by a huge amount.  Probably somewhere around 66%-75%.  That doesn't mean they have to pass that savings on to customers.

When they talk about a 25% discount, that's likely because they're looking at what the market will bear currently.  They're already cheaper than the competition, so there's not much reason for them to immediately lower prices a lot.  The 25% discount is enough to get a few customers to take the perceived risk of using re-used first stages.

Longer-term, they have said they want to lower costs greatly to expand the market.  But they have to do that carefully, to avoid losing out short term by lowering costs too quickly.  Perhaps they'll offer new companies that want to do large numbers of launches of cheap satellites long-term quantity discounts while keeping prices high until those new companies are in business.

If a new competitor showed up that could be cost-competitive, they could likely immediately lower costs to undercut that competitor.

It's also important to keep in mind that SpaceX has long term commercial crew and cargo contracts locked in or soon-to-be-locked in with NASA and those will cover much of SpaceX's fixed costs, allowing them to price commercial launches based largely on marginal costs.

That's why what they plan to charge isn't the key to understanding whether a competitor could match them on price.  The key is to understand SpaceX's cost structure and compare that to a competitor's cost structure.