StratoLaunch Redesign

kbd512 · 2016-09-03 04:35:55

I find the latest project from Scaled Composites fascinating, but for the life of me I can't figure out why Burt designed this thing the way he did. I realize I don't have any of his engineering expertise, but I seem to recall that the Air Force figured out how to expel an ICBM's from a C-5 decades earlier. One of the stated secondary uses for the aircraft was cargo transport. The arrangement they're using has to create a massive amount of drag (two fuselages and a massive payload slung on a center pylon between the fuselages). I can't imagine that it's more efficient or even less technically challenging to separate what amounts to the world's largest store from the world's largest aircraft. There's also the possibility that the rocket could strike the tail of the aircraft, an undoubtedly catastrophic event for both vehicles.

What kind of loading would the fuselage be subjected to if the rocket was mounted on a rollers and simply ejected from the rear cargo ramp in a climb using a drogue chute? Are the forces exerted on the fuselage too great for the airframe to reasonably withstand?

Although rear ejection clearly changes the pitching moment of the aircraft, it would seem to have the effect of orienting the aircraft and rocket in an optimal launch attitude. If the launch vehicle was secured on rollers with four or more points of contact and the vehicle is parachute ejected, I would think the stresses placed on the rocket and airframe would be lower than the stresses applied to either using the present strong back configuration. Perhaps my understanding of what's going on here is incorrect, though.

It would also seem that escape options for astronauts using the present configuration are limited. If the rocket were stored in an internal cargo bay, the astronauts could conceivably egress from their capsule and bail out if the launch aircraft malfunctioned in flight.

An air-launched rocket could conceivably deliver two to four astronauts to ISS or nominal resupply consumables using a much smaller rocket. As a consequence of various design aspects mandated for man-rated systems, the rocket may not be much less expensive than Falcon 9 or similar rockets. For typical payload masses delivered to ISS, this has to be more efficient than ground launch rockets.

See any pattern here:
CRS-1 delivered 1.2t to ISS
CRS-2 delivered 1.5t to ISS
CRS-3 delivered 2t to ISS
CRS-4 delivered 2.2t to ISS
CRS-5 delivered 2.3t to ISS
CRS-6 delivered 2t to ISS
CRS-7 was to deliver 1.8t to ISS, but failed
CRS-8 delivered 3.1t to ISS

Why should we use such massive and complicated rockets as Falcon 9, Antares, or Atlas for delivery of such nominal quantities of cargo?

If we have an air launched rocket that can deliver 5t to ISS (spacecraft + astronauts or cargo), I can't see a reasonable argument for using far more capable and complicated launch vehicles to deliver this kind of tonnage.

Excluding development costs, how close could we come to a $5M per unit for small, single use rocket capable of delivering 5t to ISS (not including payload adaptor hardware, operational costs, or payload integration costs)?

Here's what I'm thinking:

Aerospike engines using turbo-machinery manufactured using 3D printing
Composite tanks built using Boeing's new robot
LOX/Jet-A propellants

RobertDyck · 2016-09-03 10:54:34

kbd512 wrote:

I find the latest project from Scaled Composites fascinating, but for the life of me I can't figure out why Burt designed this thing the way he did. ... The arrangement they're using has to create a massive amount of drag (two fuselages and a massive payload slung on a center pylon between the fuselages).

Drag is roughly proportionate to the cross-section area of the fuselage. A single fuselage large enough to contain a Falcon 5 rocket would have more cross-section area than two small fuselages plus the rocket slung beneath the centre line. That means what you propose would have more drag, not less.

Stratolaunch originally proposed launching Falcon 5 from White Knight 2. Falcon 5 was to have 3.4m diameter, and 5 Merlin 1C engines. The upper stage would have a single Merlin Vacuum 1C engine, just like Falcon 9. So the rocket family would be Falcon 1 with a single engine, Falcon 5 with 5 engines, and Falcon 9 with 9 engines. SpaceX later announced they didn't want to build and inventory that many different rocket stages, so Falcon 5 would just be Falcon 9 with 4 engines removed, and propellant tanks not fully loaded. That increased diameter and length of both stages, increasing dry mass. That screwed with aerodyanamic characteristics, White Knight 2 could not lift it to required launch altitude.

Astronautix: Falcon 5

Stratolaunch tried coming up with a design for a new aircraft, based on White Knight. This new aircraft would have the same layout as White Knight and White Knight 2, but larger. It would air launch Falcon 9, called Falcon 9 Air. I thought it was cancelled, but Wikipedia reports they're still working on it: Scaled Composites Model 351

Coming back to the design of the aircraft. White Knight was originally design to carry SpaceShipOne. That was designed for the X-Prize, and to meet X-Prize rules it had to be able to carry 3 adults. It never did carry 3, but it had to be capable of it. The deal with Virgin Galactic is this would be followed by a scaled-up version for tourists. White Knight 2 would launch SpaceShipTwo. It would carry 6 passengers plus 2 crew. White Knight 2 was not designed to carry a stream lined cylindrical rocket, it was designed to air-launch the delta wing spacecraft. Its design is optimal.

You could argue for asymmetrical fuselages. A larger one for crew, and a narrow one with less drag that only provides structural support for the tail. An aircraft like that was built in World War 2. However, this aircraft would have high drag while carrying the spacecraft, then suddenly less carry mass and less drag when the spacecraft separates. Balancing aerodynamic forces is extremely complicated for that change. It's far simpler to make the aircraft symmetrical. KISS: Keep It Simple Stupid.

kbd512 · 2016-09-03 14:31:43

RobertDyck wrote:

Drag is roughly proportionate to the cross-section area of the fuselage. A single fuselage large enough to contain a Falcon 5 rocket would have more cross-section area than two small fuselages plus the rocket slung beneath the centre line. That means what you propose would have more drag, not less.

Rob,

You're clearly referring to White Knight 2, but this thread is about StratoLaunch. Your frontal area argument is applicable to White Knight 2, not Stratolaunch.

RobertDyck wrote:

Stratolaunch originally proposed launching Falcon 5 from White Knight 2. Falcon 5 was to have 3.4m diameter, and 5 Merlin 1C engines. The upper stage would have a single Merlin Vacuum 1C engine, just like Falcon 9. So the rocket family would be Falcon 1 with a single engine, Falcon 5 with 5 engines, and Falcon 9 with 9 engines. SpaceX later announced they didn't want to build and inventory that many different rocket stages, so Falcon 5 would just be Falcon 9 with 4 engines removed, and propellant tanks not fully loaded. That increased diameter and length of both stages, increasing dry mass. That screwed with aerodyanamic characteristics, White Knight 2 could not lift it to required launch altitude.
Astronautix: Falcon 5

What rocket are they launching with it now that they've parted ways with SpaceX and Orbital?

RobertDyck wrote:

Stratolaunch tried coming up with a design for a new aircraft, based on White Knight. This new aircraft would have the same layout as White Knight and White Knight 2, but larger. It would air launch Falcon 9, called Falcon 9 Air. I thought it was cancelled, but Wikipedia reports they're still working on it: Scaled Composites Model 351

Are they working on it with SpaceX?

RobertDyck wrote:

Coming back to the design of the aircraft. White Knight was originally design to carry SpaceShipOne. That was designed for the X-Prize, and to meet X-Prize rules it had to be able to carry 3 adults. It never did carry 3, but it had to be capable of it. The deal with Virgin Galactic is this would be followed by a scaled-up version for tourists. White Knight 2 would launch SpaceShipTwo. It would carry 6 passengers plus 2 crew. White Knight 2 was not designed to carry a stream lined cylindrical rocket, it was designed to air-launch the delta wing spacecraft. Its design is optimal.

I'm aware.

RobertDyck wrote:

You could argue for asymmetrical fuselages. A larger one for crew, and a narrow one with less drag that only provides structural support for the tail. An aircraft like that was built in World War 2. However, this aircraft would have high drag while carrying the spacecraft, then suddenly less carry mass and less drag when the spacecraft separates. Balancing aerodynamic forces is extremely complicated for that change. It's far simpler to make the aircraft symmetrical. KISS: Keep It Simple Stupid.

I was arguing for carrying the launch vehicle internally in StratoLaunch, not White Knight 2.

RobertDyck · 2016-09-03 15:09:50

Wikipedia shows an artist's image with each fuselage based on a 747. However another image on that same page shows size comparison with other aircraft. That image shows each fuselage based on White Knight 2. Is your argument based on interpretation by an artist who didn't know what he's doing? Do you have any engineering drawing, or better yet images of built hardware?

kbd512 · 2016-09-03 17:38:58

RobertDyck wrote:

Wikipedia shows an artist's image with each fuselage based on a 747. However another image on that same page shows size comparison with other aircraft. That image shows each fuselage based on White Knight 2. Is your argument based on interpretation by an artist who didn't know what he's doing? Do you have any engineering drawing, or better yet images of built hardware?

Rob,

StratoLaunch has pictures of the aircraft they're actually building on their website and those pictures have been posted on various other websites as well. There's no need to guess at the accuracy of an artist's interpretation of what's being built. There are pictures of the airframe in the hangar where it's being constructed. A quick search with any major search engine will find them. It's been photographed from multiple different angles and with pieces of equipment of known size next to the airframe.

I've been a little scarce here lately because I'm building a small single seater for personal enjoyment. That doesn't make me an aerospace engineer or anything close to it (and I think I stated that in the second sentence of my original post), but I have some basic working knowledge of aerodynamics from the books that I have, actually building an airframe, and of course, flying.

Once again, why transport that rocket outside of the airframe between two fuselages when it could be carried internally with less of a drag penalty in a lower weight and simpler airframe? I understand why White Knight 2 was designed the way it was. StratoLaunch was supposed to be able to launch some variation of an Orbital (that Stratolaunch found to be cost prohibitive) or a SpaceX rocket (that SpaceX is either not building or not talking about building) to LEO. Their own product literature states that StratoLaunch is intended to deliver ~5t (maybe up to 6t) class payloads. Although this is just my opinion, you probably don't need a massive two fuselage airframe with the rocket slung under a strong back to do that.

Stratolaunch.pdf

StratoLaunch also stated that they want to use their aircraft to deliver cargo. This makes sense because eventually this aircraft is going to have to start paying the bills. There simply aren't enough 5t class payloads waiting in the wings for less expensive launch vehicles. I can't think of a commercially successful heavy cargo transport aircraft that transports the cargo outside the airframe. Although it can technically carry a heavier payload than the AN-225 (227t vs 200t; supposedly the AN-225 can carry a 250t payload but that's never been demonstrated, to my knowledge), it's not going to carry that 227t payload very far (2200km) when it's subject to the massive amount of drag that the externally slug load generates. By way of comparison, the AN-225 can carry a 200t payload 4000km. The Orbital rocket would actually fit inside the cargo bay of the AN-225 if the wings were folded. I can't find the dimensions of the F9 Air, but the cargo bay of the AN-225 is 4.4M high, 6.4M wide, and 43M long (although given the shape of typical rockets you could probably get an extra 5M for a sufficiently rounded nose cone).

RobertDyck · 2016-09-03 18:12:28

Images on various websites look like computer graphics, not photographs. The image in your pdf looks different again from the images on Wikipedia. The fuselage is narrow, and low to the ground, landing gear with short struts like a modern airliner. Designed to make maximum use of composites, minimum heavy metal. The cockpit is small, and the fuselage top smoothly flows from a low slung cockpit to a high mounted wing. I don't see a problem with the design. Form follows function.

kbd512 · 2016-09-04 05:19:32

RobertDyck wrote:

Images on various websites look like computer graphics, not photographs. The image in your pdf looks different again from the images on Wikipedia. The fuselage is narrow, and low to the ground, landing gear with short struts like a modern airliner. Designed to make maximum use of composites, minimum heavy metal. The cockpit is small, and the fuselage top smoothly flows from a low slung cockpit to a high mounted wing. I don't see a problem with the design. Form follows function.

When considering aircraft performance, it can be helpful to review certain information about the aircraft's design that affects its flight characteristics. Review the characteristics and performance data of the two aircraft being compared with each other below and then make inferences based on that information.

StratoLaunch
MTOW: 591000kg
Takeoff Thrust: 154772kg
Takeoff Roll at MTOW: 3650M
Wing Area: 420M^2

AN-225
MTOW: 640000kg
Takeoff Thrust: 140,727kg
Takeoff Roll at MTOW: 3500M
Wing Area: 385M^2

The longer takeoff roll required by the StratoLaunch aircraft, in comparison to the AN-225 aircraft, is best explained by which aspect of StratoLaunch's design?

A. Weight
B. Power
C. Aerodynamics
D. Wing Area

If you answered "C", you are correct. The aerodynamic design of a specific aircraft can substantially affect the aircraft's performance in all regimes of flight. If you selected any other answer, you may want to reconsider your decision to pilot aircraft before you get yourself killed.

To reiterate what I said earlier, I think that if the rocket was carried internally and parachute ejected from a rear cargo ramp that the aerodynamic qualities of the airframe would be markedly improved. Apart from the 5M payload shroud, the rockets will fit inside the cargo bay of the AN-225 and the AN-225 can technically lift the payload. More importantly, when there were no rockets to be launched the aircraft could still be making money by delivering cargo.

I also think four GE90-115B's would've been better engine options than six PW4056's. However, we're talking about $100M for the GE's and the Pratt's were probably purchased for a fraction of that price. That's hanging an extra 7.5t on the wings, but gaining an extra 55t of thrust at takeoff. If you lose one of the GE's, you still have slightly more thrust than all six Pratt's. Fuel consumption works out in favor of the GE's and the extra weight on the wings would be fuel consumed by the Pratt's to get to launch altitude. The GE's would also likely permit the rocket to be carried to 13000M before release.

No government-sponsored space agency would permit their people to launch from a vehicle with no possibility of escape in an emergency, but that might be an acceptable risk for commercial crews. Thus far, there isn't a rocket to use with StratoLaunch so that's not too much of a concern at this point.

I'm a Rutan fan and I'm not knocking his excellent work. I'm just a little mystified as to why he didn't simply design a heavy cargo transport that could double as a rocket carrier instead of a rocket carrier that was unlikely to ever double as a heavy cargo transport.

GW Johnson · 2016-09-04 11:01:00

I actually know Burt a little. I met him and his brother long ago at Mojave. He's retired now, but his Scaled Composites outfit has a life of its own now, mostly as the replacement "Skunk Works" operation for the Lockheed portion of Lockheed-Martin.

When you do unique-aircraft design-build for paying customers for a living, you do exactly what the customer asks for, or you don't get the business. It's really bad with government projects, but the same effect also prevails in non-government business.

That's why they built a rocket carrier that could not also serve as a cargo transport. I think it was stupid, too, but that's what they were contracted to do.

GW

Antius · 2016-09-04 13:29:18

Why not just modify a 747 as a carrier? A well established technology, for which parts are cheap and available everywhere and development costs are long forgotten. Building an entirely new aircraft effectively doubles development cost. You could pick up a second hand 747 at a fraction of the cost and there are engineers capable of servicing it at airports all over the world. And then there is the question as to whether a heavy lift aircraft built specifically to carry a launch vehicle can compete against something like a 747 for cargo transport? Doesn't make a lot of sense to me.

Using an aircraft as a launcher does place inherent limits on the payload that can be delivered to orbit. Hence we come back to the 1-tonne (or few tonnes) at a time question. Going for volume production of relatively small vehicles and bringing down costs that way.

Last edited by Antius (2016-09-04 13:41:30)

SpaceNut · 2016-09-04 19:44:08

A quick look around the web tells me that this is a larger version of the Pegasus rocket with a new carrier plane with more capability to get larger cargo to orbit.

kbd512 · 2016-09-06 00:30:26

Presumptions

1. It’s unlikely that StratoLaunch will ever be anything other than a one-off airframe specifically for ATK’s Thunderbolt. We’ll presume the positive here by stating that within the next two or three years, StratoLaunch will be in-service and capable of launching Thunderbolt. Over-sized payloads requiring launch vehicle dimensional flexibility will use StratoLaunch.

2. For the concept behind StratoLaunch to attain commercially viable and attract a substantial customer base, a number of fundamental design changes to the launch aircraft are required that ultimately dictate construction of a general-purpose launch aircraft that can also transport heavy cargo between rocket launches to offset the cost associated with development and construction.

3. We’ll trade up-front procurement costs associated with major systems like engines, landing gear, and avionics so long as those trades minimize operating costs. To the extent practical, existing commercial aircraft engines, landing gear, control systems, and avionics will be used or adapted to minimize development costs. The airframe design should be substantially similar to commercial heavy cargo transport or military heavy bomber designs for the same reason.

There are two proven methods for rocket separation that I can think of, each with specific advantages and disadvantages.

1. Internal Payload Separation (B-52):

Advantages

Fuselage Diameter Minimization

Four 777 bogies modified with shorter main struts, positioned fore and aft of the payload bay in a configuration similar to the B-52’s landing gear configuration, would minimize fuselage diameter. The 777’s main gear is steerable and four units can easily support a 500t MTOW, which would be approximately 85% of StratoLaunch’s 590t MTOW. Thus, a 5M diameter fuselage would be entirely sufficient for a rocket with a 4M diameter payload shroud since the wing box can be built into a structure faired into the top of the fuselage in the same manner used by most commercial heavy cargo transport designs, to include StratoLaunch.

CG Shift Minimization at Payload Separation

The airframe should simply lurch upwards if the rocket is simply dropped like a massive bomb from the cargo bay. A winch could potentially lower the rocket from the cargo bay if clean separation was in question. The same mechanism could be used for payload mate / de-mate operations. A rather simple spectra or kevlar cargo net could uniformly support the weight of the rocket. A single release mechanism connected to all tie-downs could remove the requirement for special structures built into the rocket body to support the weight of the rocket at a specific attachment point or points.

Disadvantages

Special Mate / De-Mate Operations

Requires multi-point articulating payload bay doors to for mate / de-mate of the rocket or cargo. Although jacking gear or an elevated platform could be used, these alternatives are typically expensive infrastructure investments that limit when and where the aircraft can be used. Either way, special cargo handling equipment and procedures are required.

Fuselage Complexity

The wing box and landing gear mounts must be connected to each other to form a strong box to transmit landing loads into a substantial structure. The rocket or payload is suspended from the wing box and top of the fuselage instead of specific mount points. This will increase the weight and complexity of the fuselage, although to what extent is an engineering question.

2. Parachute Separation (C-5 design):

Conventional Cargo Handling

With roll-on / roll-off cargo handling, existing commercial cargo handling equipment could potentially be used. As it relates to cost, this should be self-explanatory. Anytime you can use existing infrastructure with little to no special equipment or procedures, cost is generally minimized.

Conventional Landing Gear

Six 747 bogies and two 747 nose gear could be used in a conventional tricycle landing gear layout. The 747 gear is less expensive than the 777 gear and the weight differential associated with these two solutions is a wash.

Disadvantages

Extreme CG Shift at Payload Separation

Although parachute extraction systems are proven to work quite well for separating heavy payloads from aircraft in-flight, no system to extract a payload in the weight class of a rocket capable of delivering a 5t payload to orbit exists and the extraction operation will substantially alter the flight characteristics of the launching aircraft.

Larger Diameter Fuselage

The fuselage will have to be larger to accommodate the rocket if it is to be extracted from the aircraft’s rear cargo ramp. This increases cost, weight, and incurs a higher drag penalty, although it’s still a better solution than an externally slung payload.

SpaceNut · 2016-09-06 18:31:48

https://www.orbitalatk.com/space-system … _Sheet.pdf

http://space.skyrocket.de/doc_lau/stratolaunch.htm

The Thunderbolt rocket, initially known as "Pegasus-2" consists of two ATK built solid-fuel stages and a restartable crogenic upper stage. The first two stages will have a Thrust Vector Control (TVC) system. The upper stage will be initially powered by two RL10C-1 engines for low earth orbit missions or by one RL10 for GTO missions.
In May 2015, Stratolaunch announced, that the Thunderbolt rocket is economically not feasable and that they are going to evaluate over 70 other launch vehicle variants.

kbd512 · 2016-09-07 15:43:30

Invariably, Vulcan Aerospace will need other paying customers for their aircraft. That typically means a fleet of aircraft, if small, and a variety of supported missions. The first paying customer that I know would be interested in heavy cargo delivery would be the US military.

The airframes I proposed could easily carry seven M1A2's or eight M1A2's with a reduced fuel load. That's four times as effective as the C-5 and since these airframes use a lot of COTS components, it's more likely than not that they'll be available when needed. The heaviest pieces of equipment that the US military routinely transports by air are armored ground vehicles and our military has lots of these vehicles to transport all over the world at a moment's notice. A fleet of 32 airframes could transport an entire armored brigade in a day.

The C-5, to include the new C-5M, can only carry two M1A2 tanks. These airframes are also typically down for maintenance more often than they're available for use. If StatoLaunch II was available and reasonably affordable, there's no doubt that our military would make use of the heavy cargo transport capability those airframes could provide. Our military already uses commercial aircraft for transporting personnel and cargo.

The ground vehicles could be loaded onto a pallet with castering wheels, wheeled up to the airframe and inserted from either side using a tug, winched into the aircraft's payload bay using equipment built into the airframe, and then pinned into the strong box.

Edit:
I didn't think about this at the time, but the StratoLaunch successor I proposed would also be a superb tanker with near 500t of gas to give. You could fly an entire squadron of F-22's, F-35's, or any other tactical fighter for that matter, to any continent with a single tanker in a single hop. For in-theatre tanking services, you could effectively support three squadrons at the same time with a single tanker.

Edit 2:
I want to clarify what I meant by carrying 8 M1A2's. Basically, StratoLaunch II could take off with its center (strong back) fuel tank empty and only carry enough fuel to rendezvous with the USAF's new KC-46A's, hit up tankers en-route to the theater of operations, and land a sizable combat force in less than 24 hours. Travel by ship and railway may take a couple weeks. That amount of time would enable virtually any peer or near-peer adversary to mobilize their military.

Edit 3:
I think another potential military application for StratoLaunch is an airborne drone carrier. StratoLaunch II could carry three squadrons of X-36 drones. The ordnance carrying capability would only be between 50kg and 70kg, but that's enough for 6 FIM-92, 6 Hydra 70 / APKWS, 1 AGM-114, a few cluster bomblets, 1 M134 minigun, or an assortment of surveillance equipment. The smaller, less powerful weapons are less likely to cause collateral damage in comparison to common overkill solutions like AGM-65's, JDAM's, and GAU-8A. While these little drones won't win any wars, they could make the cost of fighting them slightly less insane.

A C-17 cost about $24K per flight hour to operate. Let's double that cost to $48K per flight hour because this is the military that we're talking about. Let's also assume that our 36 somewhat stealthy X-36 drones each cost $2K per flight hour to operate. There are more sophisticated aircraft in terms of avionics and engines that cost substantially less to operate, per flight hour, but this is the military so let's assume higher operating costs. I realize that the MQ-1B's cost per flight hour is well north of $3K, but there are various reasons for that which are unrelated to maintenance of the drone. That brings our operating costs to about $120K per flight hour. That's on par with the per flight hour cost of two F-35's.

The F-35 may be the best platform around for fighting adversaries with similar machines, but at $60K per flight hour that's just not affordable for whacking terrorists. The lower number of available aircraft also means that the F-35 may not be available when needed, as a function of their scarcity. The grunts probably don't need an expensive 5th generation attack aircraft to whack terrorists with. X-36 drones may not be as sleek and sexy as the latest and greatest fighters from Skunkworks, but you can see how they just might be immediately available when requested. It's affordable, highly available, and persistent close air support.

Last edited by kbd512 (2016-09-13 02:17:25)

kbd512 · 2016-09-11 12:45:01

The most important aspect of StratoLaunch II has yet to be discussed, so I'll put forth a launch vehicle proposal.

An ideal air launched rocket would be an expendable two stage LOX/Jet-A powered design. I specify Jet-A instead of RP-1 because no attempt will be made to reuse the rocket and the nozzle will feature an ablative liner rather than contend with kerosene polymerization problems encountered when using lower grades of kerosene for regenerative cooling. To attain maximum Isp, these engines must use full-flow staged combustion. Staged combustion complicates the design somewhat, but means the rocket can be smaller and lighter than a rocket powered by engines using gas generators. The specification of Jet-A instead of RP-1 permits StratoLaunch to burn the rocket's propellant to reduce landing weight in the event of a launch abort. Conceivably, the rocket could be partially fueled in-flight from StratoLaunch's fuel tanks.

The feasibility of using aerospike nozzles should probably be investigated to reduce the length of the rocket. This rocket starts its flight at 12 km in altitude, so there is less atmospheric pressure variance to contend with compared to a sea level launch.

Basically, we're talking about an updated RS-76 optimized for higher altitude operation.

Antius · 2016-09-12 06:14:36

kbd512 wrote:

The most important aspect of StratoLaunch II has yet to be discussed, so I'll put forth a launch vehicle proposal.
An ideal air launched rocket would be an expendable two stage LOX/Jet-A powered design. I specify Jet-A instead of RP-1 because no attempt will be made to reuse the rocket and the nozzle will feature an ablative liner rather than contend with kerosene polymerization problems encountered when using lower grades of kerosene for regenerative cooling. To attain maximum Isp, these engines must use full-flow staged combustion. Staged combustion complicates the design somewhat, but means the rocket can be smaller and lighter than a rocket powered by engines using gas generators. The specification of Jet-A instead of RP-1 permits StratoLaunch to burn the rocket's propellant to reduce landing weight in the event of a launch abort. Conceivably, the rocket could be partially fueled in-flight from StratoLaunch's fuel tanks.
The feasibility of using aerospike nozzles should probably be investigated to reduce the length of the rocket. This rocket starts its flight at 12 km in altitude, so there is less atmospheric pressure variance to contend with compared to a sea level launch.
Basically, we're talking about an updated RS-76 optimized for higher altitude operation.

How about a single stage with drop tanks? Store the first stage burn propellant in a doughnut shaped ring around the outside of the upper stage and drop it off prior to second stage burn. It would complicate the plumbing system a little, but that way you only need 1 engine instead of two.

kbd512 · 2016-09-12 10:58:47

Antius wrote:

How about a single stage with drop tanks? Store the first stage burn propellant in a doughnut shaped ring around the outside of the upper stage and drop it off prior to second stage burn. It would complicate the plumbing system a little, but that way you only need 1 engine instead of two.

Do you mean having a Soyuz-like core with a fuel tank wrapped around it? That might work.

Edit:

LOX/RP-1 or LOX/Jet-A requires something like a 95% propellant mass fraction. I'm not very sure that that's doable and that's why I said it might work.

If the composite tanks were reinforced using the method shown below, would they be strong enough and light enough to make staging unnecessary?

In-plane strength enhancement of laminated composites via aligned carbon nanotube inter laminar reinforcement

I doubt it. The tanks have to be incredibly light weight for this to work at all. The real problem here is the extreme Delta-V requirement.

This is a GW question.

A hypothetical ramjet attachment on a SSTO rocket (designed to deliver a 6t payload) functions as a nozzle skirt encircling an aerospike rocket engine. The rocket engine's turbo pump feeds fuel into the ramjet for combustion. For sake of argument, let's say the ramjet attachment could be jettisoned to reduce weight and drag. This "first stage" accelerates the rocket to 2km/s. Another 7km/s dV is still required to attain orbital velocity.

Is it even possible for the tanks and engine to be light enough to remove the requirement for staging if we're using LOX and Jet-A or RP-1?

Last edited by kbd512 (2016-09-12 20:33:13)

Antius · 2016-09-14 03:55:48

kbd512 wrote:

Antius wrote:
How about a single stage with drop tanks? Store the first stage burn propellant in a doughnut shaped ring around the outside of the upper stage and drop it off prior to second stage burn. It would complicate the plumbing system a little, but that way you only need 1 engine instead of two.
Do you mean having a Soyuz-like core with a fuel tank wrapped around it? That might work.
Edit:
LOX/RP-1 or LOX/Jet-A requires something like a 95% propellant mass fraction. I'm not very sure that that's doable and that's why I said it might work.
If the composite tanks were reinforced using the method shown below, would they be strong enough and light enough to make staging unnecessary?
In-plane strength enhancement of laminated composites via aligned carbon nanotube inter laminar reinforcement
I doubt it. The tanks have to be incredibly light weight for this to work at all. The real problem here is the extreme Delta-V requirement.
This is a GW question.
A hypothetical ramjet attachment on a SSTO rocket (designed to deliver a 6t payload) functions as a nozzle skirt encircling an aerospike rocket engine. The rocket engine's turbo pump feeds fuel into the ramjet for combustion. For sake of argument, let's say the ramjet attachment could be jettisoned to reduce weight and drag. This "first stage" accelerates the rocket to 2km/s. Another 7km/s dV is still required to attain orbital velocity.
Is it even possible for the tanks and engine to be light enough to remove the requirement for staging if we're using LOX and Jet-A or RP-1?

I am not familiar with the arrangements for Soyuz. My thoughts are that most of the dry mass of a stage is in the propellant tanks. These are quite cheap - HSLA steel costs about $0.5/kg, is quite easy to weld and the geometry of a propellant tank can be quite simple if we don't get stupid with weight optimisation. Engines are more expensive - they require precise engineering, cooling, gimbaling, etc. Instead of having two stages, with the need to stage separation, separate engine, etc, why not build a single stage with a single engine with propellant tanks that you can just dump? If the vehicle is pressure fed and chamber pressures are kept to say 20 bar, the propellant can be transferred to the engine module by flexible lines that can be easily detached.

For that matter, maybe a N2O/propane SSTO could be built in this way, with a single pressure-fed engine taking the vehicle all the way to orbit? So long as the tanks are cheap and problems of geometry, valving, plumbing and separation can be solved, this may provide a more cost optimum approach than 3 expendable stages. The expensive bits of the rocket, such as engine, manoeuvring and guidance system are part of the SSTO and get reused. The cheap steel tanks get dumped. If the tanks can be produced for $2/kg, then for an overall mass ratio of 50, they would add ~$10/kg to the launch cost of payload. If the vehicle is pressure-fed and fundamentally simple and easy to repair and turn-around, then its capital and operational costs will be small anyway. Perhaps this is a practical way to the holy grail of $100/kg launch costs.

kbd512 · 2016-09-14 14:58:35

Antius wrote:

I am not familiar with the arrangements for Soyuz. My thoughts are that most of the dry mass of a stage is in the propellant tanks. These are quite cheap - HSLA steel costs about $0.5/kg, is quite easy to weld and the geometry of a propellant tank can be quite simple if we don't get stupid with weight optimisation. Engines are more expensive - they require precise engineering, cooling, gimbaling, etc. Instead of having two stages, with the need to stage separation, separate engine, etc, why not build a single stage with a single engine with propellant tanks that you can just dump? If the vehicle is pressure fed and chamber pressures are kept to say 20 bar, the propellant can be transferred to the engine module by flexible lines that can be easily detached.

Steel Tanks - A good idea from a cost standpoint, as long as the weight is reasonable. Typical HSLA's come in somewhere near 8t/m^3. The common bulkhead monocoque steel tanks proposed for ACES by ULA indicated that a .92 propellant mass fraction was achievable with stainless steel. That's not good enough for a LOX/RP-1 SSTO. Tank pressurization with propellants or nitrogen is required to prevent them from collapsing under their own weight and that may complicate operations, even if production cost is low.

Engines - Non-reusable with ablative nozzle liners instead of complicating the design with regenerative cooling and reusability. I still think a turbopump fed, full-flow staged combustion engine is the way to go here- especially if only one turbopump is required. The government can pick up the tab for the engine development since it's the primary beneficiary of a lower total cost to orbit system for resupply of ISS.

Staging - Complicates the launch vehicle design, but lowers weight. This thing has to have a diameter of about 4M or less to fit inside the 5M diameter fuselage. A total vehicle length of 30M or less would be ideal.

Antius wrote:

For that matter, maybe a N2O/propane SSTO could be built in this way, with a single pressure-fed engine taking the vehicle all the way to orbit? So long as the tanks are cheap and problems of geometry, valving, plumbing and separation can be solved, this may provide a more cost optimum approach than 3 expendable stages. The expensive bits of the rocket, such as engine, manoeuvring and guidance system are part of the SSTO and get reused. The cheap steel tanks get dumped. If the tanks can be produced for $2/kg, then for an overall mass ratio of 50, they would add ~$10/kg to the launch cost of payload. If the vehicle is pressure-fed and fundamentally simple and easy to repair and turn-around, then its capital and operational costs will be small anyway. Perhaps this is a practical way to the holy grail of $100/kg launch costs.

NOP propellant produces Isp values only slightly better than current solid rocket tech. I don't know whether or not a SSTO that can be air launched is practical with those kinds of Isp values. I think the rocket will weigh far too much for the launching aircraft to reasonably lift it. Moreover, virtually all SSTO's have very high Isp and very low vehicle mass fractions, both of which drive up costs. It may be possible, but it isn't practical at any reasonable cost.

ATK's Thunderbolt weighs 227t, using two solid stages followed by a LOX/LH2 stage for orbital insertion. In other words, the same ridiculously expensive technology set used by STS. I've been told that solid rockets are cheaper than liquid rockets, but the people who state that always leave out the part about how massive the solid rocket will be to lift a payload of a given tonnage or the fact that an incredibly complex and expensive LOX/LH2 stage is nearly always used in conjunction with solid rockets. RL-10's are $38M a pop and Thunderbolt uses two of them. Those two RL-10's cost as much as a Falcon 9 launch (rocket + launch services).

I need a rocket that costs $5M per copy or less and $2.5M per copy or less is highly desirable.

I'll make some sort of attempt at an operations analysis, assuming USAF owns the StratoLaunch II aircraft.

StratoLaunch II Aircraft Purchase Cost: $250M (USAF owned; customer's launch insurance required to cover aircraft purchase)

Fuel Costs: $20K per flight hour (using four GE90-115B; customer pays for fuel; 4 hour flight typical) - A 777-300ER's two GE90-115B's consume 7.35t of fuel per hour at cruise, so 14.7t per hour, which works out to about $19K per hour

Lightning Rocket (ATK already took the name "Thunderbolt"): $5M

Customer pays salaries of government employees while those employees perform services for them, with a three day minimum purchase package. Perhaps some sort of deal could be worked out with with service providers if regular deployment schedules can be maintained.

USAF Ground Crew: 20 maintainers likely required (12 for engines and airframe, 2 for avionics, 2 for fueling, 4 for cargo handling; deployed with aircraft)

USAF Air Crew: 3 required (pilot, co-pilot, range safety officer; deployed with aircraft)
Mission Specialists: 4 (flight controller, range safety officer, launch vehicle monitor, payload monitor; customer provides flight controller, vehicle, and payload monitors)

With that kind of government/industry cost-sharing, total launch costs could conceivably come in at around $10M. For payloads between 3t and 6t, the cost of the rocket becomes a major factor in the total launch costs. If a smaller version of BEAM could be created with a power and propulsion module attached to the other end, it could be a lot less expensive to deliver cargo to ISS. The cost per ton is higher, but the total cost of the cargo delivery solution is far lower than current solutions.

NASA awarded Bigelow Aerospace a $17.8M to construct. Let's say that a smaller version using the same technology could be built for $15M per copy or $13M with a block buy of six units per year (ISS resupplied every other month). That means ISS cargo resupply may only cost $138M per year. That's still a lot of money, but it's affordable for NASA. The agency presently pays between $1B and $1.5B per year for resupply.

I couldn't hazard a guess as to what a 2 seat capsule would cost, but it has to be significantly less expensive than the $114M Soyuz, $160M Dragon V2, or Orion $406M capsules that were intended for exploration missions and substantially over-engineered for ISS taxi service.

The commercial space program provided an invaluable opportunity to grow that emerging market, but the focus should remain on cost control and there's no cost benefits associated with any of the capsule solutions put forth for delivering two astronauts to ISS every six months.

SpaceNut · 2019-04-13 20:15:36

First flight out of the hanger....
Stratolaunch, the giant aircraft developed by Paul Allen, just took its first flight in California

Stratolaunch, the world's largest airplane and built to launch rockets.

Stratolaunch was a spinoff from Allen’s backing for the SpaceShipOne private space effort that won a $10 million prize in 2004. For more than seven years, Stratolaunch has been working with Mojave-based Scaled Composites on the project, which aims to use the plane as a flying launch pad for orbital-class rockets.

The plan ahead calls for further tests over the next 12 to 18 months, with the aim of getting the plane fully certified by the Federal Aviation Administration. Stratolaunch has already struck a deal to use Northrop Grumman’s Pegasus XL rocket to send payloads weighing as much as 816 pounds (370 kilograms) to low Earth orbit. Launches would begin once the plane, nicknamed Roc, wins full certification.
Stratolaunch’s air-launch system is designed to carry multiple rockets up to an altitude of about 40,000 feet, and then drop them into the air to fire up their rocket engines. The advantage of such a system is that it can take off from any runway that’s long enough to accommodate the plane, fly around bad weather if need be, and launch a satellite into any orbital inclination.

kbd512 · 2019-04-21 18:00:57

SpaceNut,

She flies!!! That is a spectacular sight!

I think it's time to consider the possibility of using airborne aircraft / drone carriers to reduce military expenditures associated with having thousands of our people deployed in vulnerable carrier battle groups.

tahanson43206 · 2020-04-05 14:48:37

Here's an update on Stratolaunch

The article at the link below includes a number of images of a new (proposed) hypersonic test vehicle:
https://www.yahoo.com/news/worlds-large … 00105.html

(th)

kbd512 · 2022-05-04 12:05:28

Stratolaunch 5th Flight:

NASASpaceFlight - Stratolaunch ROC Test Flight 5 | World's Largest Aircraft By Wingspan

kbd512 · 2022-05-04 12:39:13

Test Flight 5 includes a structural wing pylon to carry very heavy payloads, such as small orbital class rockets or various experimental aircraft. Late this summer, the Stratolaunch "Roc" carrier aircraft will drop its first Talon-A Mach 6 experimental aircraft. A "captive carry" test flight will precede the first "drop" flight. Roc will be capable of dropping up to three fully fueled Talon-A hypersonic test vehicles per flight to increase the pace of testing. Talon-A is a reusable experimental hypersonic drone aircraft intended to better understand a powered hypersonic flight regime.

Edit: According to Lead Pylon Engineer, Grace Wang, of Stratolaunch, the empty port and possibly starboard fuselage space aboard Roc will eventually contain a tank farm that includes cryogenic fuels for its payloads, such that the carried rockets or aircraft can be fueled in-flight, after takeoff, before drop / launch.

Last edited by kbd512 (2022-05-04 12:43:16)

SpaceNut · 2022-05-04 20:06:13

Its been quite a long time since its flights started.

Mars_B4_Moon · 2023-05-30 14:18:38

Stratolaunch Buys Virgin Orbit's Rocket-Launching 747

https://www.universetoday.com/161643/st … ching-747/

New Mars Forums

Announcement

#1 2016-09-03 04:35:55

StratoLaunch Redesign

#2 2016-09-03 10:54:34

Re: StratoLaunch Redesign

#3 2016-09-03 14:31:43

Re: StratoLaunch Redesign

#4 2016-09-03 15:09:50

Re: StratoLaunch Redesign

#5 2016-09-03 17:38:58

Re: StratoLaunch Redesign

#6 2016-09-03 18:12:28

Re: StratoLaunch Redesign

#7 2016-09-04 05:19:32

Re: StratoLaunch Redesign

#8 2016-09-04 11:01:00

Re: StratoLaunch Redesign

#9 2016-09-04 13:29:18

Re: StratoLaunch Redesign

#10 2016-09-04 19:44:08

Re: StratoLaunch Redesign

#11 2016-09-06 00:30:26

Re: StratoLaunch Redesign

#12 2016-09-06 18:31:48

Re: StratoLaunch Redesign

#13 2016-09-07 15:43:30

Re: StratoLaunch Redesign

#14 2016-09-11 12:45:01

Re: StratoLaunch Redesign

#15 2016-09-12 06:14:36

Re: StratoLaunch Redesign

#16 2016-09-12 10:58:47

Re: StratoLaunch Redesign

#17 2016-09-14 03:55:48

Re: StratoLaunch Redesign

#18 2016-09-14 14:58:35

Re: StratoLaunch Redesign

#19 2019-04-13 20:15:36

Re: StratoLaunch Redesign

#20 2019-04-21 18:00:57

Re: StratoLaunch Redesign

#21 2020-04-05 14:48:37

Re: StratoLaunch Redesign

#22 2022-05-04 12:05:28

Re: StratoLaunch Redesign

#23 2022-05-04 12:39:13

Re: StratoLaunch Redesign

#24 2022-05-04 20:06:13

Re: StratoLaunch Redesign

#25 2023-05-30 14:18:38

Re: StratoLaunch Redesign

Board footer