Passenger market for suborbital, hypersonic transports.

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I saw that this weeks Space Access '09 conference,, will have several presentations by companies working on suborbital flights for tourism.
According to this article, Virgin Atlantic is planning on marketing just suborbital flights at $200,000 and it reports a survey said orbital flights might be commercially viable at $500,000:

Space tourism survey targets cost factor.
Online results hint at future price points for suborbital and orbital flights.
By Leonard David
Senior space writer
updated 4:53 p.m. ET, Tues., Oct. 3, 2006
"Pricey seats.
"So far, orbital space tourism has been the propelled
province of well-heeled millionaires. Even for projected
suborbital jaunts — up to the edge of space and return to
Earth — the price tag for a Virgin Galactic spaceliner
seat slaps your purse or wallet for roughly $200,000.
Several key results of the space tourism survey point out:
The prices of current space treks into suborbital and
orbital are generally too high at present, with only 7
percent registering for a suborbital flight and 4 percent
for an orbital adventure at current price levels.
Suborbital flights would really take off at $25,000, and
orbital flights at $500,000, if such price levels were
compatible with an operator’s business plan. If price were
not an issue, nearly two-thirds of the respondents would
want to go on a round-the-moon adventure."

I want to argue here that it would be feasible to provide service also for a much larger market: suborbital, hypersonic passenger flights for transcontinental and intercontinental transportation.
A round trip cross-Atlantic ticket on the Mach 2 Concorde cost around $10,000. I don't think it's out of the question that a substantial number of business executives and wealthy vacationers would be willing to pay $100,000 to make a cross-Atlantic or cross-U.S. trip that took less than an hour, especially when it included making a short stint to space in the process.
Likewise I think there would be a substantial market at $100,000 per ticket for a trip to Asia that only took 2 or 3 hours, compared to a full day as it does now.

You can make a calculation for how much fuel you would need for a rocket flying horizontally to reach a certain distance by using the rocket equation for velocity:

Vf -Vi = Ve*ln(Mi/Mf), where Vf, Mf are the final velocity and final mass, and Vi, Mi are the initial velocity and initial mass, and Ve is the exhaust velocity. The formula still works for intermediate points in the trip where you burned only a portion of the fuel, where Vf and Mf are the values at these intermediate times.
Let's say you're burning propellant at a rate r kgs/sec. Then the mass of the vehicle at time t will be Mf = Mi-rt. I'll say the initial velocity Vi is zero, and let the velocity at time t be V(t). Then the formula becomes:

V(t) = Ve*ln[Mi/(Mi-rt)]. Then we can integrate this formula for velocity to get the distance traveled, S(t):

S(t) = Ve*t - (Ve/r)*(Mi-rt)*ln[Mi/(Mi-rt)]

This formula is for the case of constant thrust, where the acceleration will gradually increase since the mass is decreasing as the fuel is used up. It might be more comfortable for the passengers if instead we used a constant acceleration flight. This would be accomplished by making the fuel flow rate, and therefore thrust, decrease as the weight decreases. The formulas for this case can be constructed in an analogous fashion to those of the classic rocket equation. I haven't calculated it but my guess is the total fuel usage would be the same as for using the fuel at a constant rate.
In any case, I will assume that just as for SpaceShipOne it will have aerodynamic shape to allow lift so that most of this propulsion can go towards providing horizontal thrust. I didn't include the drag in this first order calculation of the constant fuel rate case, but it can be added in a more detail examination. You can reduce the drag by having the craft undergo the hypersonic flight at high altitude. You can save fuel to reach this altitude by using a carrier craft such as the White Knight for SpaceShipOne. Note that you don't have to use the fuel on the carrier craft or suborbital vehicle to get to a height of say 100 km, but only to get to high enough altitude to reduce the drag and heating on the vehicle at the hypersonic velocities.
XCOR is planning on using kerosene and LOX for their engines so I'll use this type of engine for getting the Ve number. Kerosene/LOX engines can have Isp of 360 s at high altitude, which I am assuming will be the only time the rocket will be used. So Ve will be in the range of 3600 m/s at high altitude.
Let's say you want to go across the continental U.S., 4500 km. For a first generation transport vehicle let's say it's comparable in size to SpaceShipOne about 1,000 kg empty and 3,000 kg fully loaded with fuel to carry one pilot and two passengers.
Let's put in some numbers in order to calculate the distance, S(t): say t = 2500 s, about 42 minutes, r = 1 kg/s, and Mi consists of a 1000 kg vehicle with passengers and 2500 kg fuel, for a total of 3500 kg. Then we calculate: S(t) = 3600*2500 - (3600/1)*(1000)*ln(3500/1000) = 4,490,000 meters, or 4,490 km. The time of 42 minutes compares to about 6 hours for a normal passenger jet to travel this distance.
The maximum speed would be Vf = 3600*ln(3500/1000) = 4500 m/s, or Mach 15, quite a high speed. The X-15 was able to reach Mach 6.7 and was planned on being able to reach Mach 8. It had an Inconel skin with a titanium frame to resist the heat loads at these high Mach numbers.
Still for Mach 15 you might need materials even more heat resistant. In this article Burt Rutan says SpaceShipOne's carbon composite structure would not be sufficient for even the Mach 6.7 speeds of the X-15:

X-15 and today’s spaceplanes.
by Sam Dinkin
Monday, August 9, 2004

Still carbon-carbon composites are used for the leading edges of the wings for the Space Shuttle which have to withstand the highest temperatures of re-entry even at Mach 25, so presumably would also work at Mach 15. These carbon-carbon composites became infamous though for how they fractured under impact by foam in the Columbia accident. It turned out they are even more brittle than fiberglass.
This is a bit puzzling because the type of carbon composites used extensively for example in modern race cars is actually more fracture resistant than steel. This makes them an ideal material for race cars since they have greater strength than steel while being more fracture resistant and at a fraction of the weight. I can only assume that at the time the shuttle was being designed, these highly fracture resistant carbon composites were not available. Then the recommendation for the thermal protection is the carbon-composites of this highly fracture resistant type.
For the vehicle to be useful as a transport craft it will have to be able to take-off and land at least at international airports. Airport safety managers might not be too enthusiastic about rocket takeoff at their airports, and certainly not enthusiastic towards deadstick landings. At least for the takeoffs this uncertainly be could ameliorated by the jet engine carrier craft.
For the landings I suggest these rocket craft also have their own small jet engines so that they can do powered landings. There are some lightweight jet engines that could work for our 1000 kg first generation craft. For instance there is the TRS-18-1 engine that can produce 326 pounds of thrust and only weighs 85 pounds:

Microturbo TRS-18-1
Engine Specifications.

Two of these would probably be sufficient for landing our 1000 kg rocket plane assuming at subsonic speeds the craft had a lift/drag ratio typical for jets, which can be at 10 and above.
A more high performance and more extensively tested jet engine to use might be the PW610F. This weighs 260 pounds and can produce 900 pounds of thrust:

Pratt & Whitney Canada PW600. ... nada_PW600

One of these would probably sufficient for our purposes. For this more high performance engine we might even be able to use it for takeoff to reach high altitude for the rocket plane, dispensing with the need for the carrier craft.
At this early stage, we would have separate jet engines and rocket engines. The jet intakes would be closed off when the rocket is operating and opened to be used only during low speed, subsonic flight. However, we can imagine with further development we would get a type of hybrid engine, as for example envisioned for the Skylon craft, where the jet and rocket engine are combined into one.

Bob Clark


Just saw this article on Rocketplane XP, which plans to offer suborbital, tourism rocket flights, while using jet engines for take-offs and landings:

Rocketplane reset
by Jeff Foust
Monday, November 5, 2007

The revised Rocketplane XP design (above) is intended ultimately to be more competitive in the emerging suborbital space tourism conference.

The Second Space Age.
March 6, 2008
Patrick Mahoney
"Ready for a space cruise? The technology is taxiing to the runway." ... e-age-0306

Rocketplane XP's current design was modified from the original Lear Jet base airframe but still has the look of a passenger business jet, with a rocket in the tail.
It has some titanium and steel portions to withstand the heat of reentry in addition to an aluminum frame. This makes it heavier than a Lear Jet and it has to use a long military base runway for take-offs and landings. However, quite likely if it used all composite materials, as does SpaceShipOne, to replace the heavy steel, titanium, and aluminum it could take off and land from a standard sized airport runway.

Bob Clark


The Europeans have also proposed a business jet model for a suborbital tourism rocket:

PICTURES: Astrium aims for 2012 suborbital tourism flights.
By Rob Coppinger

The space jet will take off from a conventional runway, powered by two jet engines, and fly to 39,300ft (12,000m), where it will ignite its liquid oxygen, methane rocket engine providing an ascent acceleration of 3g. After 80s the jet will reach 196,000ft and coast to its apogee. ... ights.html

Interestingly, they consider this as a precursor to a point-to-point transport.

Another article on the proposed Astrium rocketplane:

Space planes 'to meet big demand'.
By Jonathan Amos, Science reporter, BBC News
Monday, 17 March 2008, 13:38 GMT
"Aerospace giant EADS says it will need a production line of rocket planes to satisfy the space tourism market."

There is a link to a nice video of a simulated flight on this page. In the video the passengers are wearing helmets with closed visors. But it doesn't look like they are wearing actual spacesuits with independent air supplies because the helmets are not connected to the rest of the suits. The helmets have more the look of motorcycle helmets. I don't know if this is really supposed

Bob Clark


Another suborbital, tourism rocket plane based on a business jet model:

Bristol Spaceplanes - Ascender.
ascender_580.gif ... nder.shtml

There have been several studies showing just for tourism there would be a sufficient market for such suborbital flights to be profitable. I have to think there would be a bigger market for cases where the traveler would actually want to go somewhere and this method could get him there in 1/10th the time.
As a point of comparison I did a search on the Japan Airlines site for round trip business class tickets from my town of Philadelphia to Tokyo.
It ranged from $6,600 to $21,000:

Select Your Flights

Philadelphia to Tokyo Thursday, April 9, 2009
Tokyo to Philadelphia Tuesday, April 14, 2009
Travelers: 1
Travel class: Business and First

Select your fare: Price differences within a fare type may be due to flight connections or availability. Prices are per adult passenger and include Taxes and Surcharges.

Fare type Fare description Lowest price
Business Saver Special Restricted. Bed-style seating on most long-haul routes -
Executive Class. more details $6,672.48
Business Saver Restricted. Bed-style seating on most long-haul routes -
Executive Class. more details $7,611.48
Business Normal Flexible. Bed-style seating on most long-haul routes -
Executive Class. more details $12,330.48
First Normal Flexible. World-renowned service and comfort - First Class.
more details $21,589.48

Note also, that the $200,000 ticket price mentioned for suborbital flights on SpaceShipOne is only for the first few flights. After, a few years the price is expected to come down to $20,000.

Bob Clark


I think the cargo market for sub orbital flight might be more lucrative. With its speed you could have same day shipping from very distant places. I also wonder how long will it take for the passenger market to develop? Yes it is fast, but concord was fast yet unprofitable. I wonder will high maintenance and fuel cost doom it or will it be small enough to succeed.


I was wondering why the first goal for that Skylon-type engine was not a suborbital plane.

It would sure be great for the advancement of safe cheap rocket technology if suborbital flights became an everyday event even if just for Celebrities. If Britney Spears gets one, they will all have to get one. Anyone who cannot have breakfast in paris, adopt an ethiopian orhan after lunch and be caught doing coke in LA that night just wont rate at all.


I think this is in the wrong forum. IMO, this should be in SB&T.


I think you're right swampcat; I'll move it there, but leave a breadcrumb trail here....


Saw these articles linked on the Wikipedia X-33 page:

Lockheed Test Flies Space Plane Prototype.
By Leonard David
Special Correspondent,
posted: 24 April 2008
11:41 am ET
"Lockheed Martin has tested a prototype reusable launch system by flying a sub-scale flight demonstrator from the site of New Mexico's proposed Spaceport America.
"The successful test flight of the proprietary vehicle took place in December and was only recently disclosed. A company official said Lockheed Martin is planning more tests using ever-larger vehicles.
"Lockheed Martin Space Systems teamed with launch provider UP Aerospace of Highlands Ranch, Colo., Dec. 19 to conduct a small demonstration launch at Spaceport America in southern New Mexico to evaluate proprietary technology the company currently has under development." ... -test.html

Lockheed loses prototype of Space reusable launch vehicle.
18 August 2008
"Golden, Colorado: Lockheed Martin's second test flight of a prototype reusable launch system failed with the craft going out of control and becoming seriously damaged, rendering it unusable. The test, conducted 12 August, saw the winged craft take off from a launch rail under its own power and fly for some 12.5 seconds of a planned flight of less than a minute before it crashed."
"The 200-pound (91 kg) vehicle reached its planned altitude of roughly 1,500 feet (457 meters). It is 8 feet (2.4 meters) long with a wingspan of about 6 feet (1.8 meters) and is roughly one-fifth in scale. It is being flown to develop techniques and procedures for quick launch, ease of operations and low cost access to space." ... artin.html

Anyone know what the scoop on this is? Since the Lockheed X-33 was canceled because of the relatively trivial problem (compared to the complexity of the rest of the system) of the composite hydrogen tank debonding, I'm inclined to think Lockheed solved that problem and it's a version of the X-33. The dimensions given though are small for it actually being a one-fifth scale of the X-33:

X-33 Advanced Technology Demonstrator.
X-33 Specifications.
Length: 69 ft
Width: 77 ft
Takeoff weight: 285,000 lbs
Fuel: LH2/LO2
Fuel weight: 210,000 lbs
Main Propulsion: 2 J-2S Linear Aerospikes
Take-off thrust: 410,000 lbs
Maximum speed: Mach 13+
Payload to Low Earth Orbit: N/A ... monstrator

If it is a version of the X-33, I wonder why it would now be classified. Perhaps Lockheed found it would be able to provide the suborbital troop delivery system wanted by the defense department. If so, it could also work as a suborbital commercial transport.

This article suggests the composite hydrogen tank debonding has been solved:

New Composite Hydrogen Fuel Tank For RLVs Successfully Tested.
Huntsville - Dec 22, 2003
"A team of engineers from Northrop Grumman and NASA's Marshall Space Flight Center, Huntsville, Ala. Have demonstrated that a new, specially designed fuel tank made from composite materials can safely hold and contain liquid hydrogen under simulated launch conditions."
"Fuel tank problems on the X-33 Venture Star project were critical to ending what was the last major new space transportation R&D program at NASA."

Several companies are also working on developing lightweight composite cryogenic tanks:

An update on composite tanks for cryogens.
More automation, improved materials bring composite fuel tanks for space applications closer to reality.
Contributed by: Sara Black, Technical Editor
Article Date: 11/1/2005 ... ogens.aspx

Bob Clark


>>In this animation of the SpaceShipTwo trip, the passengers also do not appear to be wearing actual spacesuits, though they do have helmets:

They aren't. Rutan believes that if you can't make a reliable pressure hull you shouldn't be flying passengers into space. He may be right. To my knowledge a pressure suit has never actually saved anyone's life in a spacecraft contingency, and it certainly isn't practical to wear them continuously. Would it have helped the guys in the Soyuz T-11? Perhaps, but that accident was caused by a very poor design, since corrected, and it could have happened anytime during the flight.


NASA has canceled most, or perhaps all, of its efforts in launch vehicle technology to pay for the Ares and Orion. The Lockheed prototype was probably a DOD project.


The launch of a military satellite yesterday at the NASA's Wallops Island facility reminded me that commercial launches are also being made from the site:

Mid-Atlantic commercial spaceport makes 1st launch.
Posted 12/16/2006 7:20 AM ET ... OE=TECISVA

There was a push by some to offer a prize for a suborbital commercial transatlantic transport to launch from the site but I don't know if that is still being considered:

Hypersonic Cruise for the V Prize.
Wednesday 2008.01.23 by gravityloss ... e-v-prize/

This article did not optimize the cruise velocity to get the best fuel fraction and gets a too high cruise speed of 6,000 m/s. A later article on this site discusses how this could be optimized, giving a cruise velocity of only 3,000 m/s if you can get a high lift/drag ratio of 7 at hypersonic speeds:

Optimum Rocket Cruise.
Friday 2009.03.20 by gravityloss ... et-cruise/

Some hypersonic waverider shapes can get a lift/drag ratio in the range of 6 to 8 when optimized for a set hypersonic cruise speed:

Waverider Design. ... ider.shtml

If the delta-v required is only 3,000 m/s this could be obtained with a rather low mass ratio: Mi/Mf= exp(delta-V/Ve) = exp(3,000/3600) = 2.3, assuming an exhaust velocity Ve of 3,600 m/s, which can be reached by kerosene/LOX rockets. This is less than the mass ratio of SpaceShipOne.

Bob Clark
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