Stratolaunch and Orbital - The Height of Air Launch

[edkyle99]

Thanks for the nice words chaps. Had a LOT of help with that one!

any idea how many G's a payload would get with this design?

My guesstimate shows low gees.  They can tailor the solids to produce lower thrust as they go, and there are two of them, so solid motor g-forces shouldn't be big.  The biggest g-force would likely be near the end of the first stage burn for lighter GTO type payloads.  The fact that they would remove one of the RL10 engines from the third stage shows that those forces would also be kept low.  It might be possible to keep acceleration in the 3-4 g maximum range, if desired.  Since they are designing this thing from scratch, they can pretty much set the g-loads wherever they want them.

 - Ed Kyle

[R7]

Since they are designing this thing from scratch, they can pretty much set the g-loads wherever they want them.

Is steady acceleration even that much of a problem for the payload (and the hydrolox US) compared to the vibration loads from solids?

[Avron]

ditto .. "Exactly. Stratolaunch is a dead end."

If Jim, Blackstar, and folks like that were saying so, I'd agree. But they are sort of defending this.

Skepticism from experts counts more to me than that from armchair engineers (like myself... for now).

If this is a commercial venture, there is no way,  based on first principals ,that they can compete in the 2017 time frame, or whenever they do get going .. costs for the service to launch at $/lb and risk cannot compete..  are far higher for the onset .. I know I will not invest..

[Lee Jay]

If this is a commercial venture, there is no way,  based on first principals ,that they can compete in the 2017 time frame, or whenever they do get going .. costs for the service to launch at $/lb and risk cannot compete..  are far higher for the onset ..

How do you know what their costs are going to be?

[Lee Jay]

Heh, you were thinking Dream Chaser as well... 

Atlas 412 (the planned LV for Dream Chaser) seems to have about twice the LEO payload capacity of this vehicle, so I don't see how this one could get DC to orbit.

they could re-engine the aircraft.  I noted that they are using old 747 engines.   New engines might do the trick.

More power doesn't give you double the capacity.  You need more lift and more structure as well.

[edkyle99]

Is steady acceleration even that much of a problem for the payload (and the hydrolox US) compared to the vibration loads from solids?

They'll have to design the vehicle to provide acceptable loads of all types to the payloads.  The short, fat solids will minimize thrust oscillation compared to longer motors.  It is all about de-tuning motors from structures.

Vega and Minotaur and Pegasus and, soon again, Athena, etc., show that a mostly solid motor launch vehicle can haul satellites.  Vega provides a ride as soft, or softer, than Ariane 5.  Ariane 6, of course, is going solid too (Pegasus 2 is almost like a 1/3rd scale Ariane 6). 

To me, this monolithic solid plus high energy upper stage configuration looks more and more like a future standard.  I would like to see a U.S. ground launched version of this type, more capable, to see if it could undercut the bloated EELV costs.

 - Ed Kyle

[Prober]

Heh, you were thinking Dream Chaser as well... 

Atlas 412 (the planned LV for Dream Chaser) seems to have about twice the LEO payload capacity of this vehicle, so I don't see how this one could get DC to orbit.

they could re-engine the aircraft.  I noted that they are using old 747 engines.   New engines might do the trick.

More power doesn't give you double the capacity.  You need more lift and more structure as well.

If the plane is just a demo then its not worth the cost.
 
But if this is a one up project, beefing up the payload area would be worth it.   I guesstimate by switching to the lighter more powerful engines the payload can be 2-4 tons added.
 

[Avron]

If this is a commercial venture, there is no way,  based on first principals ,that they can compete in the 2017 time frame, or whenever they do get going .. costs for the service to launch at $/lb and risk cannot compete..  are far higher for the onset ..

How do you know what their costs are going to be?

From first principals we have an additional cost of the carrier aircraf, if it was any way as efficient as a 747, and was used at a high rate.. "International Civil Association Organization, the average direct operating (airborne) cost of a B 747-400 in the year 2000 was $6,761 per hour"

So lets assume that out the box they got it all right .. I just don't see how that would get away with less than $10K per hour.. oh the ground costs " ground costs are around 70 percent of the airborne costs in 2003."

Maybe there are better sources: http://askville.amazon.com/cost-airline-fly-commercial-jet-York-Los-Angeles/AnswerViewer.do?requestId=2593308

but anyway you hack it..these costs will be added to the LV cost.. so make the investment in the carrier pay off you need a high flight..carrier costs are not going to help you much in lowering the total launch costs.

Oh, you say , but the concept gains you some high and velocity.. wow all of what 11Km and 0.8 mach on a very good day.. these figures are a drop in the ocean compared to the needs .. the cost of a little extra gas on the Lv at say 1% of lv cost, will get  to the same height and velocity for a lot less.

From a cost to orbit , its "failure is the only option"...  I am not investing..

[Lee Jay]

From first principals we have an additional cost of the carrier aircraf,

And the reduction of the cost of a launch pad, which is a very expensive thing.  Both need a vehicle integration facility of some sort.

Pads can cost hundreds of millions to build and get operational.  Look at what Orbital just went through with Antares.  They know those costs first hand.

if it was any way as efficient as a 747, and was used at a high rate.. "International Civil Association Organization, the average direct operating (airborne) cost of a B 747-400 in the year 2000 was $6,761 per hour"

So lets assume that out the box they got it all right .. I just don't see how that would get away with less than $10K per hour.. oh the ground costs " ground costs are around 70 percent of the airborne costs in 2003."

$10k per hour for a 3 hour launch campaign that has an overall cost that's in the tens of millions is so low it's not even worth mentioning.

How about this...a single scrub due to weather can cost over a million dollars.  If this thing saves that cost on a regular basis, that can amount to a big savings.

[renclod]

From first principals we have an additional cost of the carrier aircraf,

And the reduction of the cost of a launch pad, which is a very expensive thing.  Both need a vehicle integration facility of some sort.

IMO They still need launch-pad-like facilities on the ground, such as:
- large area lightning protection
- LOX and LH2 handling (tanking + detanking)
- solids handling

Range safety must still be available from the hangar on to all the lenght of the runway. Need secured perimeter for hangar and runway. Bird ingestion in engine(s) is an extra threat. If the aircraft sits incapacitated at the far end of the runway they need a way to detank cryogenics there.

[robertross]

From first principals we have an additional cost of the carrier aircraf,

And the reduction of the cost of a launch pad, which is a very expensive thing.  Both need a vehicle integration facility of some sort.

IMO They still need launch-pad-like facilities on the ground, such as:
- large area lightning protection
- LOX and LH2 handling (tanking + detanking)
- solids handling

That's more like aircraft ground facilities with an industrial base.
Actually, it's a lot like shuttle landing facilities, with prep for SRBs.

[Avron]

From first principals we have an additional cost of the carrier aircraf,

And the reduction of the cost of a launch pad, which is a very expensive thing.  Both need a vehicle integration facility of some sort.

Pads can cost hundreds of millions to build and get operational.  Look at what Orbital just went through with Antares.  They know those costs first hand.

if it was any way as efficient as a 747, and was used at a high rate.. "International Civil Association Organization, the average direct operating (airborne) cost of a B 747-400 in the year 2000 was $6,761 per hour"

So lets assume that out the box they got it all right .. I just don't see how that would get away with less than $10K per hour.. oh the ground costs " ground costs are around 70 percent of the airborne costs in 2003."

$10k per hour for a 3 hour launch campaign that has an overall cost that's in the tens of millions is so low it's not even worth mentioning.

How about this...a single scrub due to weather can cost over a million dollars.  If this thing saves that cost on a regular basis, that can amount to a big savings.

If only.. these are additional cost on top of the LV cost and that is flight time.. ground time is at a discount 30% less.. now do the math..  no savings.. more risks.. more cost.. less lbs to orbit for the $

[edkyle99]

Oh, you say , but the concept gains you some high and velocity.. wow all of what 11Km and 0.8 mach on a very good day.. these figures are a drop in the ocean compared to the needs .. the cost of a little extra gas on the Lv at say 1% of lv cost, will get  to the same height and velocity for a lot less.

This type of air launch method offers gains of perhaps 400-500 m/s delta-v over a ground launch equivalent.  Almost all of the gain is due to the initial altitude, not the speed.  A ground launch version would need to weigh perhaps 25-30% more than an air launched version to lift the same payload.  That's not trivial.

Any comparison of air versus ground has to compare two launch sites versus one air strip site, given azimuth limitations of U.S. ground sites.

 - Ed Kyle

[Lee Jay]

If only.. these are additional cost on top of the LV cost and that is flight time.. ground time is at a discount 30% less.. now do the math..  no savings.. more risks.. more cost.. less lbs to orbit for the $

Please forget the flight time - it's nothing.  And what you did wasn't doing the math, it was hand waving.  If you're going to do the math, then you need to have the numbers and do it.  You don't have the numbers.

[joek]

...
In my opinion, it's for the direct-to-GTO market. Unless it costs less than existing launchers, it probably won't see many customers for inclined orbits. So that leaves direct insertion into GTO.

A couple of the existing players in the GTO business are, SeaLaunch, which for approx 100 million dollars a pop, is able to do 6 tonnes direct to GTO. SpaceX, which for around 54 million dollars a pop, is able to do about 4 tonnes to GTO, launching from about 29 degrees north.

Not sure why they wouldn't be competitive for NGSO?  Seems that given the ability to "dial an azimuth" they would have some advantages.  Also, the NGSO market has been increasing and is projected to increase significantly over the next 10 years with total NGSO satellites exceeding GSO by ~50% (altho number of NGSO launches is projected to be significantly lower than GSO launches).

For GSO over the next decade, 60% (13.7 launches/yr) of the projected market is for satellites up to 5400kg, and 40% (9.1 launches/yr) for satellites up to 4200kg.  That seems sufficient without having to complete in the heavy class (>5400kg ).  For more information on those forecasts, see here.

[Elmar Moelzer]

Shouldn't someone say something about the economics?

I'm sure they can do the engineering for this & it's not impossibe to find the development money but what's this rocket for?

In my opinion, it's for the direct-to-GTO market. Unless it costs less than existing launchers, it probably won't see many customers for inclined orbits. So that leaves direct insertion into GTO.

A couple of the existing players in the GTO business are, SeaLaunch, which for approx 100 million dollars a pop, is able to do 6 tonnes direct to GTO. SpaceX, which for around 54 million dollars a pop, is able to do about 4 tonnes to GTO, launching from about 29 degrees north.

Both exist now, both are operating now, and come 2018 when this rocket is set to enter service, they (Falcon 9 certainly) are likely to be launching frequently. So to make any headway in the market, this rocket would have to cost less than 100 million dollars to put 4-6 tonnes into GTO, and less than 54 million to put less than 4 tonnes into GTO.

Call me Mr. Negative on this but is it really likely to go anywhere?

I dont get how this is supposed to change anything. What exactly is their business mode? Why do they think they will attract paying customers for their manned version? It is obviously not going to be cheaper than alternatives for manned missions, but rather it is going to be more expensive. The added flexibility and responsiveness, the main improvement offered by the giant airplane wont really matter that much for manned launches either. That would be more relevant for military missions, I would presume. So I dont see how this is ever going to get them their investment back.

Exactly. Stratolaunch is a dead end.

Launch when needed. less chance of weather problems. No problems with the range being tide up or a problem with the launch pad.

As I said, that is about the only advantage that I see of airlaunch with a 3 stage expendable rocket versus ground launch with a cheaper (and partially reusable) rocket.

For crew, who wants to pay for a launch to LEO and then have it delayed. If it is a tourist then they loose out do to bad weather and if they need to return to work can't get a new launch date. For commercial they don't want down time on a station. For some examples.

I dont buy it. The cost of access to LEO is right now the biggest limiting factor for space tourism. This does not reduce the cost of access to LEO. It wont make a difference to the current situation.

I only see a very limited amount of customers who would be willing to pay a (probably) significant premium for more responsiveness and more flexibility. The military being the main one.

I disagree. There is some real possibility for quite interesting concepts... I kind of think they're not strongly partnering, but XCOR's two-stage fully reusable orbital rocket concept seems very well-suited to using something like the Stratolaunch carrier.

XCORs two stage fully reusable system would indeed change things, but that is not what they are doing right now. Right now they are going with Orbitals 3 stage expendable and that is what I was referring to. I would say something very different, were they to do the XCOR thing.

[RocketmanUS]

For crew, who wants to pay for a launch to LEO and then have it delayed. If it is a tourist then they loose out do to bad weather and if they need to return to work can't get a new launch date. For commercial they don't want down time on a station. For some examples.

I dont buy it. The cost of access to LEO is right now the biggest limiting factor for space tourism. This does not reduce the cost of access to LEO. It wont make a difference to the current situation.

I only see a very limited amount of customers who would be willing to pay a (probably) significant premium for more responsiveness and more flexibility. The military being the main one.
{snip}

For space tourist it might only be one per year ( adding to their total launches for the year for their business case ). A space tourist personnel schedule might not be flexible enough for ground launch with possible launch delays.

Keep in mind the price is not everything when launching a payload.

[Avron]

If only.. these are additional cost on top of the LV cost and that is flight time.. ground time is at a discount 30% less.. now do the math..  no savings.. more risks.. more cost.. less lbs to orbit for the $

Please forget the flight time - it's nothing.  And what you did wasn't doing the math, it was hand waving.  If you're going to do the math, then you need to have the numbers and do it.  You don't have the numbers.

I did my math,, Elon did it before.. I will not invest, you are welcome to do so.. I have all the numbers I need.. and all of them are above and beyond a basic LV..

[Avron]

Oh, you say , but the concept gains you some high and velocity.. wow all of what 11Km and 0.8 mach on a very good day.. these figures are a drop in the ocean compared to the needs .. the cost of a little extra gas on the Lv at say 1% of lv cost, will get  to the same height and velocity for a lot less.

This type of air launch method offers gains of perhaps 400-500 m/s delta-v over a ground launch equivalent.  Almost all of the gain is due to the initial altitude, not the speed.  A ground launch version would need to weigh perhaps 25-30% more than an air launched version to lift the same payload.  That's not trivial.

Any comparison of air versus ground has to compare two launch sites versus one air strip site, given azimuth limitations of U.S. ground sites.

 - Ed Kyle

initially when I looked at air launch, I wondered what had taken so long, STS came an went...  a $200 M  launch needed $500M just to get to the pad..  the LV was supposed to be reusable, it was rebuild-able .. in a commercial world that would have been dead,,. but because the powers controlled the people.. nothing hatppened.. other than waste.. but I digress...

There is a finite size that can be air-launched,,  that is minute compared to what can be ground launched.. size matters, as it should bring down the cost to orbit.. so its game over at start..  again, first principals tell me not to invest. you are welcome to do so.. 

[Lee Jay]

I did my math,,

Show your work.