Intercontinental Single-Stage Sub-Orbital

[sanman]

Tell me, would it be feasible to design a sub-orbital vehicle that could serve the rapid intercontinental travel market?

So it would take off vertically, and land horizontally somewhere on the opposite side of the world. And it would be traveling through the vacuum in between.

Imagine it being used only for cargo at first, but then much later it would eventually achieve a man-rating to allow rapid intercontinental passenger flights.

So the goal of this vehicle would not be to achieve orbit, but to provide rapid intercontinental suborbital travel/transport. We're talking about being able to land on the other side of the world in less than an hour.

Economics would dictate that this be a single-stage vehicle, for ease of turnaround.
Beyond that, what design features would this market niche role compel?

[RanulfC]

Well to keep you trajectory out of the lower Van-Allen belt you'd haved to shallow up the angle and probably have to have some sort of "skip-glide" air-breathing portion of the flight. IIRC you're looking at a 'cruise' velocity of Mach-6 or greater and a high hypersonic L/D in order to carry it off. (External burning fuel/air as a ramjet engine helps with the L/D issue)

Randy

[sanman]

But what if we don't want an airbreathing hypersonic solution? Why must we have one?

What if you want to ballistically coast through the vacuum, to minimize your flight time?

It says here that the inner Van Allen radiation belt begins at 200km:

http://en.wikipedia.org/wiki/Van_Allen_radiation_belt

That's above LEO, so why would a suborbital vehicle be in danger of traveling into the Van Allen belts? I don't think anybody worries about SpaceShipOne/Two hitting the Van Allen belts.

The idea behind this vehicle is that it should use rocket propulsion through the vacuum in order to achieve rapid intercontinental transit.

Because it would be used for commercial transport purposes, it should be designed to maximize payload capacity. Hopefully this would not necessarily balloon the size of the vehicle, since it only has to achieve a suborbital trajectory rather than achieving orbit.

[Jorge]

It says here that the inner Van Allen radiation belt begins at 200km:

http://en.wikipedia.org/wiki/Van_Allen_radiation_belt

That's above LEO,

Incorrect. 200 km is not above LEO.

[sewand]

Do a search on Philip Bono's Icarus/Pegasus VTOVL concepts for intercontinental sub-orbital transport.   As I understand it, he was optimistic on the mass fractions.  But they are interesting ideas... and I think suborbital transport could be the killer app for rocket transport. 

[Ronsmytheiii]

Well if you dont mind a vertical landing, it has already been invented:

[kkattula]

Basically, the delta-v required to go inter-continental, point to point, is quite close to what's required to get to orbit. That's why the early satellite launchers were often re-purposed ICBMs, with reduced payload.

A purely ballistic trajectory needs to go thousands of km into space.  Depressed trajectories designed to stay at lower altitudes reduce range or payload.

Another option is to launch into LEO, then do a re-entry burn after a fraction of an orbit. But that requires a full SSTO capable vehicle.

IIRC, the Saenger antipodal bomber skip-glide concept has been shown to be rather optimistic in its assumptions. Specifically in hypersonic L/D and re-entry thermal load.

[sanman]

The energy requirements to go intercontinental may be similar to what's required to achieve orbit. But the market demand for rapid intercontinental transport will likely outpace demands for orbital satellite launches for quite some time.

Optimized economics trumps optimized physics. I'm assuming that a rocket-based intercontinental transport would be the most economical form of rapid intercontinental transport. Is that a reasonable assumption?

Hypersonic flight is still vapoware, but rockets have been carrying humans for over half a century. (I assume the X-15 rocketplanes were rockets and not jetplanes.)

So why not a Skylon that uses rockets instead of scramjets? What's the disadvantage from using the more proven rocket technology?

[butters]

Rapid intercontinental transport via a vertical takeoff rocket is largely oxymoronic because of the logistical overhead in placing payloads on top of vertical rockets and/or erecting vehicles from horizontal to vertical.

By the time you set up the rocket with its payload and have it tanked up for launch, you might as well have sent the payload via cargo jet. Explain to me a vertical launch system that can handle 10 or more launches per day from a single pad and then maybe we can begin to consider the practical economics.

Otherwise we're talking about a horizontal takeoff system with airport-like logistics, and that to me optimizes out to something rather like the Reaction Engines A2 hypersonic transport concept that would do Mach 5 at 85,000 feet with antipodal range (anywhere in the world from anywhere in the world).

But it's still tough to sell a few hours across the world over less than 24 hours across the world if it costs several times more. Overnight intercontinental transport is quite sufficient for most time-sensitive business, and it stands to question whether the value of faster transport would be worth the associated price.

Finally, I'll just briefly note that Skylon does not involve scramjets and does indeed involve a staged-combustion rocket cycle with a precooled turborocket cycle and bypass ramjets for the airbreathing portion.

[kkattula]

The energy requirements to go intercontinental may be similar to what's required to achieve orbit. But the market demand for rapid intercontinental transport will likely outpace demands for orbital satellite launches for quite some time.

What I was trying to explain is that a VTVL rocket-based intercontinental transport is effectively the same thing as a VTVL orbital transport. That's how difficult it is.

Optimized economics trumps optimized physics.

Really? I don't understand what you mean by that, but I don't think I want to fly in your rocket.

I'm assuming that a rocket-based intercontinental transport would be the most economical form of rapid intercontinental transport. Is that a reasonable assumption?

No.  Teleportation could be cheaper, and a lot faster. 

Or for a more practical solution, mag-lev trains running in vacuum tunnels at hypersonic speeds. Very expensive to build, but massive throughput of passengers.

[Archibald]

For example, a flight of about 10,000 kilometers would require a delta-V of over 7,300 meters/second, which is already about 80% of that required to reach low Earth orbit.

During my involvement with a hypersonic vehicle program in the late 1980s, the rule of thumb was that once you got over about 5,000 meters/second, the difference between that and an orbital reentry environment were small.

There's certainly a "sweet spot" between the two - I mean a reasonable distance balanced with a reasonable speed. 
Perhaps rocket powered hypersonic point-to-point transportation could be done for a range of 1000 to 3000 km

[sanman]

I don't understand how a fraction of an orbit is different from a purely ballistic trajectory - both involve unpowered coasting. I don't see why every ballistic trajectory has to go thousands of miles into space, when you can have a shallow ballistic trajectory.

Let's imagine a powered "flatter" trajectory, rather than one that goes thousands of km into space. But that flatter rocket trajectory would still for the most part take place in a vacuum, as opposed to the upper-atmospheric flight of a hypersonic vehicle.

Since it was mentioned in previous posts that a horizontal takeoff vehicle is more economical to load than a vertical takeoff one, then let's assume that one.

An SSTO vehicle is considered beyond the range of current state of the art capabilities. But there's no reason to say that Single-Stage SubOrbital vehicle is beyond the state of current technology.

Let's suppose that our SSS vehicle uses LOX-Kerosene, as an economical fuel, and is traveling from NewYork to Tokyo, or from London to Sydney.

What kind of flight time can we expect, and what kind of G-forces along the way?

[RanulfC]

IIRC, the Saenger antipodal bomber skip-glide concept has been shown to be rather optimistic in its assumptions. Specifically in hypersonic L/D and re-entry thermal load.

Quite optimistic given the lack of knowledge at the time. When the idea was examined again in the late 60s the entire concept was pretty much found to be less viable than originally assumed. However, a LOT of the information was simply rejected out of hand simply because it was part-and-parcel of the concept. Another more critical review was undertaken in the late '80s to mid-'90s which used both the gained knowledge data-base and high end CFD modeling among other things to examine the idea of "hypersonic-skip-gliding" without specifically connecting a vehicle concept to the technique.

It was found that skip-gliding actually WOULD work and work quite well given some minimum design criteria and since then suggestions have been made to improve both the basic concept and to provide "up-grades" and work-arounds for some of the efficiency and Hypersonic Lift-to-Drag ratio issues.

The advanced work done in the United States was a program concept called "Hyper-Soar" which would have a hypersonic spaceplane launched from the US which would use a combination of skip-gliding trajectory and ram/scramjet "power-boosts" during the atmospheric "skip" portions of the flight, generally extending each "glide" segment and maintaining a higher average flight speed over the entire mission.

An early 2000-ish ESA report showed that a vehicle with a hypersonic L/D ratio of around 4.0 using external burning combustion during a skip-glide trajectory could do an Earth circumnavigation flight at an averge speed of Mach-10 using much less overall fuel/energy than previously assumed.

But what if we don't want an airbreathing hypersonic solution? Why must we have one?
What if you want to ballistically coast through the vacuum, to minimize your flight time?

A ballistic trajectory isn't necessarily the "least-time" trajectory in fact it is usually not. "Ballistic missile" is somewhat a misnoumer as they don't actually fly a "ballistic" trajectory but a highly depressed angle powered trajectory.

Nothing says you HAVE to have an "airbreathing" solution, you can replace the external-burning ramjet with rocket engines and just fire them at the bottom of each "skip" to re-accelerte the vehicle and extend the next glide phase. However that would require more on-board storage as you're providing both fuel and oxidizer for the engines, and you also loose the L/D boost that external burning provides. So it's a trade off.

And you DO want vacuum "coasting" time to allow radiation cooling of your vehicle between "skips" but with a purly ballistic trajectory you only GET one "reentry" event so your TPS has to be able to handle the higher-heat pulse.

It says here that the inner Van Allen radiation belt begins at 200km:

http://en.wikipedia.org/wiki/Van_Allen_radiation_belt

That's above LEO, so why would a suborbital vehicle be in danger of traveling into the Van Allen belts? I don't think anybody worries about SpaceShipOne/Two hitting the Van Allen belts.

::::grin::: Lets recall that 100km is "officially" the start of space, and that "LEO" is not a single defined orbit and is actually a "speed" rather than an altitude

Having said that, common Low-Earth-Orbits usually end up being somewhere between 100-300 "nautical" miles or 115 to 300 "actual" miles or between 185-556km with the majority of orbits filling the space between the inner and outer belts simply because the air-drag below the inner belt is pretty bad at orbital speeds.

Nobody worries about a "suborbital" tourism vehicle like SpaceShip-Two hitting the Van Allen belts because their maxium altitude which is determined by their maximum speed in a Class-1 (Suborbital: Straight-up/Straight-down) trajectory is far too low to achieve the needed altitude. (SS-2 will top out at around Mach-4 or around 1.3kps)

For Class-2 trajectories, (Suborbital: Point-To-Point) which is what you're talking about, your velocities have to be higher because you are adding significant horizontal velocity as well as vertical climb. The further you "aim" to go the higher your peak altitude will be because the faster you will have to travel. In a ballistic flight path as you near speeds of around Mach-8 to Mach-10 your flight path climbs into the lower Van-Allen belt quickly.

The idea behind this vehicle is that it should use rocket propulsion through the vacuum in order to achieve rapid intercontinental transit.

So...

1) Rocket powered take off to around Mach-4 at an angle of around 70 or more degrees to exit the atmosphere. Maximum Altitude would be around 100km.
2) Once "in-space" you apply the rockets to achieve horizontal velocity to around Mach-10. A bit more, a bit less depending on various factors but close enough for this example. Cut engines and coast.
3) Re-fire engines occasionally to adjust trajectory to increase range and avoid falling back to Earth short of your goal.
4) Reenter at around Mach-10 and slow to a glide and fly to destination to land.

Does that sound about like what you're thinking?

Because it would be used for commercial transport purposes, it should be designed to maximize payload capacity. Hopefully this would not necessarily balloon the size of the vehicle, since it only has to achieve a suborbital trajectory rather than achieving orbit.

It would depend on a huge amount of more specific information but no matter what your overall "payload" would be less than a similar capacity/range subsonic aircraft simply because of nature of a rocket powered suborbital vehicle.

Do a search on Philip Bono's Icarus/Pegasus VTOVL concepts for intercontinental sub-orbital transport. >>snip<<  But they are interesting ideas... and I think suborbital transport could be the killer app for rocket transport.

While the concepts are very interesting, part of the overall issue was that the only actual "suborbital" transport of the group of concepts (the Pegasus) couldn't achieve the needed flight perameters without a major boost from a rocket powered sled and track up the side of a mountain.

ALL the other vehicles were in essance Single-Stage-To-Orbit Vehicles used to provide ballistic point-to-point service instead. Even the Pegasus was designed as a viable upper stage spacecraft able to handle all aspects of orbital flight and a bit more simply because it WAS a suborbital vehicle primarily.

IS suborbital point-to-point (P2P) high-speed/fast package-delivery (as it's listed currently) "THE" killer-ap for rocket transports? Opinions still differ on the idea with major questions over the "assumption" that the world is even ready for point-to-point delivery services.

Some reading:
http://www.suborbitalinstitute.org/FAQ.html

http://www.space.commerce.gov/library/reports/2002-10-suborbital-LowRes.pdf

http://www.nss.org/tourism/Suborbital_presentation.pdf

http://www.sei.aero/com/projects/displayindex.php?id=3
(I highly recommend the papers here as the "Fast-Forward-Group" is an industry self organized group doing actual money and economic studies in order to quantify the current technical and economic challenges that need to be addressed to move this concept into reality.)

NOTE TO ALL: This is the "final" report just issued (March, 2010) by the Office of Commercial Space Transportation, FAA so is of interest to everyone.
http://www.faa.gov/about/office_org/headquarters_offices/ast/media/point_to_point.pdf

(Found here with a lot of other interesting pointers: http://www.faa.gov/about/office_org/headquarters_offices/ast/)

And a few more:
http://www.isunet.edu/index.php?option=com_docman&task=doc_download&gid=519

http://spaceinvestmentsummit.com/lcr3/presentations/7_Services_Splinter_Session_Materials/7.1_Transport_Matrix.ppt

http://dspace.mit.edu/bitstream/handle/1721.1/9253/45537132.pdf?sequence=1

Randy

[RanulfC]

Rapid intercontinental transport via a vertical takeoff rocket is largely oxymoronic because of the logistical overhead in placing payloads on top of vertical rockets and/or erecting vehicles from horizontal to vertical.

While I won't argue the overall assumptions per se...

By the time you set up the rocket with its payload and have it tanked up for launch, you might as well have sent the payload via cargo jet. Explain to me a vertical launch system that can handle 10 or more launches per day from a single pad and then maybe we can begin to consider the practical economics.

Any Soviet era ICBM site can handle multiple launchers per day with only a few hours needed to load the "next-shot" rocket with pre-packaged payload. There ARE some downsides to this as an economical example though

Payload intergration with rocket vehicles is CURRENTLY time-consuming simply because it is an exacting tasking with variable and complex operations and handling issues due to the very much "one-of-a-kind" payload and launcher interaction and connection. Given an actual "need" for the development of a more intergrated and faster payload system the majority of current aircraft payload operations and equipment is quite suitable for payload/launcher operations.

However this would mean actually designing and building reusable rockets and the infrastructure to go with and support them.

YOU assume that current launch operations are "required" for any vertical take off and/or landing rocket vehicle but this is simply not true. Example launch facilty for high-flight rate launch and landings? The reinforced concrete pad(s) the DC-X flew from in New Mexico proved that the currently over-regulated and quite expensive launch facilities in current use are NOT required for a properly designed vehicle. However that same pad would have to have added equipment and facilites to handle any "normal" launch vehicle so it is quite clear the launch facilites are much less an issue than the vehicles themselves.

The key is the questions of "practical-economics" and market for suborbital point-to-point versus current long range air transport.

While you feel that the Mach-5, A-2 transport would "economical" for the suggested mission however the fact that it ONLY travels at Mach-5 and remains inside and is dependent ON the atmosphere is self limiting in capability and economics in and of itself. A subsonic take-off and landing, rocket boosted suborbital vehicle with an average speed of Mach-10 actually faces less stress and is easier to engineer than the A-2 and using denser fuels would probably be smaller and carry more payload.

This doesn't mean such a vehicle has any more of an opportunity in being built, but looking at the situation honestly it is easier and more practical to build such a vehicle as I've described for long-distance fast-package delivery services than a Mach-5 air-breathing only transport aircraft.

So we are back to the original question:

Optimized economics trumps optimized physics. I'm assuming that a rocket-based intercontinental transport would be the most economical form of rapid intercontinental transport. Is that a reasonable assumption?

Is it a "reasonable" assumption? It really depends on what your assumptions concerning the economics and market for and of intercontinental transport are, but currently the answer would be "NO" because current transportation systems and market studies show no great clamoring for faster transport.

However, there is a clear indication that industry and the market would leap on the chance to have access to more effective timely transport, but this is tempered with an overall caution due to the relative immaturity of, and lack of economic data-base for rapid inter-continental transport.
The current case stands at someone needing to "build-it" (prove out the concept AND the economics) and the market and public will come. But not until then.

Note: You wrote:

Hypersonic flight is still vapoware, but rockets have been carrying humans for over half a century. (I assume the X-15 rocketplanes were rockets and not jetplanes.)

Learn your history! Especially if you are planning on using it to bolster your argument!

Point of fact: The X-15 rocket PLANES were in fact built to fly and study the hypersonic (above-Mach-5) flight regime and did so extensivly. They proved out the techniques, materials, and issues with flying for extended times at hypersonic speeds. It should be noted that almost all "manned" rockets have traveled routinly at hypersonic speeds both going into space and returning from space. Hypersonic speeds above Mach-6 have proved mostly probematical due to high aerodynamic stress and heating which is why a lot of the study for hypersonic transport systems include some means of active cooling (using the assume cryogenic fuel) or a "skip-glide" type flight to allow radiative cooling.

Hypersonic flight is NOT "vaporware" and neither is hypersonic Air-Breathing flight, but then again "intercontinental" rocket flight is on the same level being quite possible, just not proven to be economical or practical.

Randy

[sanman]

Nothing says you HAVE to have an "airbreathing" solution, you can replace the external-burning ramjet with rocket engines and just fire them at the bottom of each "skip" to re-accelerte the vehicle and extend the next glide phase. However that would require more on-board storage as you're providing both fuel and oxidizer for the engines, and you also loose the L/D boost that external burning provides. So it's a trade off.

Fair enough - it's understood that rockets have to carry the extra LOX weight, since they're not burning in air. On the other hand, scramjets have to withstand the prolonged atmospheric frictional heating, which probably entails its own weight penalty. Plus, even scramjets have inferior power-to-weight than rockets, right? (I'm talking about the apparatus, not the fuel+LOX)

So...

1) Rocket powered take off to around Mach-4 at an angle of around 70 or more degrees to exit the atmosphere. Maximum Altitude would be around 100km.
2) Once "in-space" you apply the rockets to achieve horizontal velocity to around Mach-10. A bit more, a bit less depending on various factors but close enough for this example. Cut engines and coast.
3) Re-fire engines occasionally to adjust trajectory to increase range and avoid falling back to Earth short of your goal.
4) Reenter at around Mach-10 and slow to a glide and fly to destination to land.

Does that sound about like what you're thinking?

Yes, that's it! That's roughly what I was picturing, for HOTOL.
But if you do it the DC-X VTVL way, perhaps steps 1 & 4 would be more abbreviated.

It would depend on a huge amount of more specific information but no matter what your overall "payload" would be less than a similar capacity/range subsonic aircraft simply because of nature of a rocket powered suborbital vehicle.

Fair enough - it's understood that you'll be flying at a higher price point than regular intercontinental atmospheric flights, but on the other hand you're getting rapid transit time for that extra money. The early applications could be military of course, but then gradually infiltrate the commercial world.

IS suborbital point-to-point (P2P) high-speed/fast package-delivery (as it's listed currently) "THE" killer-ap for rocket transports? Opinions still differ on the idea with major questions over the "assumption" that the world is even ready for point-to-point delivery services.

Well, the world should be ready to move on, since commercial air travel hasn't evolved for a long time. It's still being done the same way as it was during the 1960s. Since then, momentum has been lost. If this were still the 1960s, we would all still be marveling at the new wonders of the "Jet Age" - but a half century later, we're all yawning at the Jet Age.

With commercial air travel now increasingly a commoditized business dominated by price-wars, there should be room to compete in a differentiated and much higher-margin space, where currently no competition exists.

If you can't come up with a broader market base in the long run, then you're condemned to living at the mercy govt contracts. If Chinese and Russian launchers prove to be too cost-competitive in the space launch business, even people like Elon Musk will be reduced to showing up at congressional hearings fretting over the meager amount of govt contracts and subsidies coming his way, and will eventually quit in frustration.

YOU assume that current launch operations are "required" for any vertical take off and/or landing rocket vehicle but this is simply not true. Example launch facilty for high-flight rate launch and landings? The reinforced concrete pad(s) the DC-X flew from in New Mexico proved that the currently over-regulated and quite expensive launch facilities in current use are NOT required for a properly designed vehicle. However that same pad would have to have added equipment and facilites to handle any "normal" launch vehicle so it is quite clear the launch facilites are much less an issue than the vehicles themselves.

The key is the questions of "practical-economics" and market for suborbital point-to-point versus current long range air transport.

Yes, this DC-X VTVL mode of transport would be an interesting one to consider for sub-orbital point-to-point intercontinental. Imagine being able to get some lifesaving medicines, supplies, or transplant organs, etc, to some other place on the globe very quickly. While converting DC-X to SSTO would be too difficult, it seems like it could be scaled up for sub-orbital flight.

Or what about even the Roton concept? Couldn't that likewise be adapted for sub-orbital point-to-point? I haven't heard anybody propose that yet. Roton ultimately could not be made workable as an SSTO, but its design could probably be adapted to achieve suborbital point-to-point.
At least Roton's overhead rotor design could be a robust way to address that "last-mile" leg of the journey (and even the "first mile" as well).

Learn your history! Especially if you are planning on using it to bolster your argument!

Point of fact: The X-15 rocket PLANES were in fact built to fly and study the hypersonic (above-Mach-5) flight regime and did so extensivly. They proved out the techniques, materials, and issues with flying for extended times at hypersonic speeds. It should be noted that almost all "manned" rockets have traveled routinly at hypersonic speeds both going into space and returning from space. Hypersonic speeds above Mach-6 have proved mostly probematical due to high aerodynamic stress and heating which is why a lot of the study for hypersonic transport systems include some means of active cooling (using the assume cryogenic fuel) or a "skip-glide" type flight to allow radiative cooling.

Hypersonic flight is NOT "vaporware" and neither is hypersonic Air-Breathing flight, but then again "intercontinental" rocket flight is on the same level being quite possible, just not proven to be economical or practical.

LOL, yes, I'm aware of what the X-15 program was about - I read plenty about it as a fascinated kid. But I was talking about scramjet propulsion vs rocket propulsion. X-15 craft were rocket-propelled and not air combustion. While rockets have been flying for over a half-century, no scramjet vehicle other than the rare test model has really flown. No actual practical missions are being carried out by scramjet vehicles today. They are still for the most part VAPORWARE.

My point in saying that, is that it's more logical to try to develop a suborbital point-to-point vehicle based on the more mature and proven rocket technology, as compared to the as yet unproven, expensive and precariously complex scramjet technology.

[kkattula]

I don't understand how a fraction of an orbit is different from a purely ballistic trajectory - both involve unpowered coasting. I don't see why every ballistic trajectory has to go thousands of miles into space, when you can have a shallow ballistic trajectory.

Orbit is not about altitude, except that you have to be high enough that air-drag is not significant. It's about having sufficient speed that you fall around the Earth rather than falling into it.

A point to point ballistic trajectory won't quite reach orbital velocity, but has to go high to avoid hitting the Earth before it's gone far enough sideways.

A fraction of an orbit is different from a purely ballistic trajectory in that you do reach orbiat velocity, then have to fire a retro engine to reduce your speed back to sub-orbital.

[sanman]

Or what about even the Roton concept? Couldn't that likewise be adapted for sub-orbital point-to-point? I haven't heard anybody propose that yet. Roton ultimately could not be made workable as an SSTO, but its design could probably be adapted to achieve suborbital point-to-point.
At least Roton's overhead rotor design could be a robust way to address that "last-mile" leg of the journey (and even the "first mile" as well).

Gee, the more I think about it, the more I like this idea. If you were to do Suborbital Point-to-Point, you certainly want a controlled landing, and even a powered landing. Coming down by parachute is too primitive.

HOTOL allows you the elegant airport departure and arrival, but then you've got to include the large heavy wings, and you need the heat shielding for a broad section of the vehicle. You may need an extra long airstrip.

The Roton concept with its overhead rotor offers the same nifty airport departure and can even land on unprepared terrain, and has a simpler trajectory, and only needs the heat shield at the bottom.

It could start out as an automated unmanned point-to-point rapid transport. Eventually,

I'm not saying that there's an immediate market for thousands of these things. But if you look at those 2 giant Antonov An-225 aircraft in existence, I'd read that they're always booked solid because of their unique ability to carry large-sized items that everybody else can't carry.

So even if you only built a dozen Roton-type suborbital rapid transports, you could probably expect that their niche capabilities would keep them quite busy. And as operations matured, operating costs would come down to reduce the pricing, resulting in more demand and more vehicles being built.

[baldusi]

Or for a more practical solution, mag-lev trains running in vacuum tunnels at hypersonic speeds. Very expensive to build, but massive throughput of passengers.

I've heard a speed of 6000km/h for such trains. So you have any paper on that? South America would be the ideal place since the distance between big cities are big (thousands of km), and there are no techtonic plates boundaries.

[RanulfC]

Fair enough - it's understood that rockets have to carry the extra LOX weight, since they're not burning in air. On the other hand, scramjets have to withstand the prolonged atmospheric frictional heating, which probably entails its own weight penalty. Plus, even scramjets have inferior power-to-weight than rockets, right? (I'm talking about the apparatus, not the fuel+LOX)

'Couple of points out front:

1) Scramjets aren't neccessarily needed as a standard subsonic-combustion ramjet can be effective up to speeds of Mach-8.

2) Ramjets or in fact most Air-Breathing engines can have higher Thrust-To-Weight ratios if you really need them, but the economics aren't usually there for them to be in general use. (Military engines for example)

3) Air-Breathing engines are "accellerator" and "cruise" type engines in that they steadly and efficently continue to accellerate the vehicle to the limits of their performance. This is not as much of an issue if the vehicle is using the atmosphere as a 'support' medium as well, (think "lifting-trajectory" using wing/body lift) however rockets are very inefficent at any sort of "cruise" mode and are pretty much just straight accelleration engines. They tend to require very high T/W ratios simply because they demand Vertical Take Off, high angle trajectories in order to get up and out of the atmosphere as soon as possible.

3) Thrust-To-Weight isn't as important in the type of suborbital flight we're discussing.

Drag and such for a ramjet is pretty low overall, better the more you "intergrate" the intake/exhaust system into the vehicle. An "external-burning" ramjet uses the body of the vehicle and the shockwaves generated by hypersonic speeds as the "walls" of the engine. By injecting fuel into a specific point the body/shockwave dynamics are used to compress the fuel air mixture which then uses the body/shockwave dynamics to allow optimum expansion of the exhaust.

You CAN do a skip-glide with rocket burns instead of air-breathing, but as I noted you lose some of the advantages available.

So...

1) Rocket powered take off to around Mach-4 at an angle of around 70 or more degrees to exit the atmosphere. Maximum Altitude would be around 100km.
2) Once "in-space" you apply the rockets to achieve horizontal velocity to around Mach-10. A bit more, a bit less depending on various factors but close enough for this example. Cut engines and coast.
3) Re-fire engines occasionally to adjust trajectory to increase range and avoid falling back to Earth short of your goal.
4) Reenter at around Mach-10 and slow to a glide and fly to destination to land.

Does that sound about like what you're thinking?

Yes, that's it! That's roughly what I was picturing, for HOTOL.
But if you do it the DC-X VTVL way, perhaps steps 1 & 4 would be more abbreviated.[/quote]
Step 1, not so much. Step one pretty much covers all types of "take-offs" that are possible. It only concerns itself with the portion of the flight from where you decide to start the suborbital run through the speed needed to get above most of the atmosphere.

Step 4 you just shorten the "flying" portion with a terminal velocity fall into range to restart your propulsion system for landing.

In the end the overall flight mechanix are the same.

Well, the world should be ready to move on, since commercial air travel hasn't evolved for a long time. It's still being done the same way as it was during the 1960s. >snip good stuff<
With commercial air travel now increasingly a commoditized business dominated by price-wars, there should be room to compete in a differentiated and much higher-margin space, where currently no competition exists.

One would think. Proving it however is the issue

[quotet]Or what about even the Roton concept? Couldn't that likewise be adapted for sub-orbital point-to-point? I haven't heard anybody propose that yet. Roton ultimately could not be made workable as an SSTO, but its design could probably be adapted to achieve suborbital point-to-point.
At least Roton's overhead rotor design could be a robust way to address that "last-mile" leg of the journey (and even the "first mile" as well).[/quote]
Actually? The original "two-person" (no cargo) ROTON was designed from the start as an SSTO vehicle. It was only when it grew bigger that it lost the SSTO ability and started having heavier issues.

I don't see any reason it wouldn't work.

My point in saying that, is that it's more logical to try to develop a suborbital point-to-point vehicle based on the more mature and proven rocket technology, as compared to the as yet unproven, expensive and precariously complex scramjet technology.

Don't get stuck on "hypersonic" meaning "scramjet" because you don't NEED scramjets to fly at hypersonic speeds. Just saying...

Randy

[sanman]

'Couple of points out front:

1) Scramjets aren't neccessarily needed as a standard subsonic-combustion ramjet can be effective up to speeds of Mach-8.

2) Ramjets or in fact most Air-Breathing engines can have higher Thrust-To-Weight ratios if you really need them, but the economics aren't usually there for them to be in general use. (Military engines for example)

3) Air-Breathing engines are "accellerator" and "cruise" type engines in that they steadly and efficently continue to accellerate the vehicle to the limits of their performance. This is not as much of an issue if the vehicle is using the atmosphere as a 'support' medium as well, (think "lifting-trajectory" using wing/body lift) however rockets are very inefficent at any sort of "cruise" mode and are pretty much just straight accelleration engines. They tend to require very high T/W ratios simply because they demand Vertical Take Off, high angle trajectories in order to get up and out of the atmosphere as soon as possible.

3) Thrust-To-Weight isn't as important in the type of suborbital flight we're discussing.

Drag and such for a ramjet is pretty low overall, better the more you "intergrate" the intake/exhaust system into the vehicle. An "external-burning" ramjet uses the body of the vehicle and the shockwaves generated by hypersonic speeds as the "walls" of the engine. By injecting fuel into a specific point the body/shockwave dynamics are used to compress the fuel air mixture which then uses the body/shockwave dynamics to allow optimum expansion of the exhaust.

You CAN do a skip-glide with rocket burns instead of air-breathing, but as I noted you lose some of the advantages available.

Well, perhaps a smaller suborbital craft wouldn't bother with skip glide, just to keep things simple.

Step 1, not so much. Step one pretty much covers all types of "take-offs" that are possible. It only concerns itself with the portion of the flight from where you decide to start the suborbital run through the speed needed to get above most of the atmosphere.

Step 4 you just shorten the "flying" portion with a terminal velocity fall into range to restart your propulsion system for landing.

In the end the overall flight mechanix are the same.

Okay, but somehow it seems like unmanned autonomous flights are better suited to vertical landing, as compared to horizontal landing.

One would think. Proving it however is the issue

Well, hopefully Virgin/Branson will see enough demand to give a solid answer.

But I noticed that Branson had commented early on about the idea of using SpaceShipTwo for quick intercontinental travel. Obviously it's not designed for that. But it then makes me wonder if a flashy-yet-conventional enterprise like his would have more eagerly leapt at the idea of a rapid intercontinental transport over a space tourist vehicle.
Aiming at space tourism means you get to be flashy first, and worry about paying the bills later. With suborbital intercontinental transport, you get to serve a more conventional market first, to pay the bills, and you have the possibility of evolving into something more flashy and Buck Rogers later on.

Actually? The original "two-person" (no cargo) ROTON was designed from the start as an SSTO vehicle. It was only when it grew bigger that it lost the SSTO ability and started having heavier issues.

I don't see any reason it wouldn't work.

I remember reading that "2 guys and a ham sandwich" slogan for original Roton, but I recall the original design also had other hangups, like trying to position the rocket combustion chambers on each of the rotor-tips, etc. That seemed a little weird and eccentric. When they switched to the FASTRAC engine, that seemed more mainstream and sober.

Don't get stuck on "hypersonic" meaning "scramjet" because you don't NEED scramjets to fly at hypersonic speeds. Just saying...

Randy

Okay, fair enough - I see that there are probably already various hypersonic designs that use rockets instead of scramjets. But if you're going to use rockets, why not free yourself from the atmosphere and pass frictionlessly through the vacuum? Yes, you'll need to carry the LOX, but for a smaller-sized vehicle it shouldn't add too much weight.

During the early period, the market for rapid intercontinental flight would be smaller, so it could probably be served by smaller-sized vehicles.
Once that market is catered to and becomes more established and experiences greater growth, then you might want to scale up and have really large transports with greater carrying capacity. That might then push you to switch away from rocket to ramjet/scramjet, so that you could get rid of the oxidizer weight and scale up your vehicle size and capacity.

[simonbp]

Well, hopefully Virgin/Branson will see enough demand to give a solid answer.

But I noticed that Branson had commented early on about the idea of using SpaceShipTwo for quick intercontinental travel. Obviously it's not designed for that. But it then makes me wonder if a flashy-yet-conventional enterprise like his would have more eagerly leapt at the idea of a rapid intercontinental transport over a space tourist vehicle.
Aiming at space tourism means you get to be flashy first, and worry about paying the bills later. With suborbital intercontinental transport, you get to serve a more conventional market first, to pay the bills, and you have the possibility of evolving into something more flashy and Buck Rogers later on.

Well, point-to-point travel is where Branson makes most of his money, so it's obviously come up. I think the idea is more that the high altitude "space tourism" will build up a safety record for the SS2 system, which can then be used to make the case at the FAA for a point-to-point license.

I know for the SOFIA airborne telescope, the largest obstacle right now is FAA approval for the many modifications they've made to the 747SP, and that approval is much harder since they are technically carrying passengers point-to-point. The microgravity aircraft get around that by having an experimental certification, and requiring all passengers to go through depressurization training in a hypobaric chamber...

[sanman]

So you're saying that maybe Branson is being extra-clever by doing "Space Tourism" thru SpaceShipTwo, because his real goal is to use it as a stepping stone to go for suborbital point-to-point transit? So he's not just another billionaire with a flair for throwing money on expensive toys? (Honestly, that's what I've really been seeing him as uptil now - just a rich guy who suddenly got bit by the space bug. Kind of like Bush launching the Constellation program after being emotionally impacted by the Columbia disaster.)

Since nobody's put any money into resurrecting or upgrading the Concorde as an intermediary step, can I take it that the Bransons of the world want to "go superfast or go home"?

[kkattula]

Concorde (in the end) couldn't make money on the busy trans-atlantic route by reducing the transit time to less than 4 hours.

How do you expect a far more expensive system to do better?

For a rocket, you will need 10 to 20 times the weight of payload in fuel. For RP-1/LOX that's about $15 to $30 per kg of payload, just in fuel.

[kkattula]

Or for a more practical solution, mag-lev trains running in vacuum tunnels at hypersonic speeds. Very expensive to build, but massive throughput of passengers.

I've heard a speed of 6000km/h for such trains. So you have any paper on that?

Not much: http://www.impactlab.net/2008/06/27/trans-atlantic-supersonic-maglev-vacuum-tube-train/

But for the cost ($50M+ per km) you're going to want very high volumes. i.e. the trans-atlantic market.

...South America would be the ideal place since the distance between big cities are big (thousands of km), and there are no techtonic plates boundaries.

IIRC, the Nazca & Antartic plates are subducting beneath the South American plate, causing those big pointy things. What do you call them? The Andes?

[simonbp]

So you're saying that maybe Branson is being extra-clever by doing "Space Tourism" thru SpaceShipTwo, because his real goal is to use it as a stepping stone to go for suborbital point-to-point transit?

Saying it's his real goal may be exaggerating, but it would an interesting side-effect of SS2 succeding. Given the huge amount of reservations on Virgin Galactic, he's already building up a potential customer base...

[sanman]

Concorde (in the end) couldn't make money on the busy trans-atlantic route by reducing the transit time to less than 4 hours.

How do you expect a far more expensive system to do better?

Well, I wasn't necessarily thinking about bringing back Concorde itself, but whether supersonic travel could be revived with a Concorde replacement that would be fasterbettercheaper.

For a rocket, you will need 10 to 20 times the weight of payload in fuel. For RP-1/LOX that's about $15 to $30 per kg of payload, just in fuel.

Well, if you use just the RP-1 without the LOX (ie. high-mach ramjet like RanulfC said) then your fuel costs are closer to existing airliners, although obviously still much higher, since you have to burn much more at lower efficiency.
Later on, when scramjet tech is more solid, you could upgrade to that.

I have another question for RanulfC or anyone else - would hypersonic flight produce enough shockwaves to be heard on the ground? That's one of the things that hurt Concorde, so that's why I'm asking. Let's assume a waverider as the worst scenario.

Btw, just as an aside, I saw a recent nice article on Hondajet on MIT's Techreview, where they mention that the engines are mounted above the wings to help reduce the noise traveling downward to the ground:

http://www.techreview.com/energy/27026/?p1=MstRcnt

[Archibald]

For example, a flight of about 10,000 kilometers would require a delta-V of over 7,300 meters/second, which is already about 80% of that required to reach low Earth orbit.

During my involvement with a hypersonic vehicle program in the late 1980s, the rule of thumb was that once you got over about 5,000 meters/second, the difference between that and an orbital reentry environment were small.

There's certainly a "sweet spot" between the two - I mean a reasonable distance balanced with a reasonable speed. 
Perhaps rocket powered hypersonic point-to-point transportation could be done for a range of 1000 to 3000 km

[kkattula]

Well, I wasn't necessarily thinking about bringing back Concorde itself, but whether supersonic travel could be revived with a Concorde replacement that would be fasterbettercheaper.

The major airliner maunfacturers have looked at that many times, but concluded there wasn't a market. In 2001 Boeing announced their Sonic Cruiser, which would fly at Mach 0.95 to 0.98, 15-20% faster than regular airliners, while being just as fuel efficient. The airlines said they would rather have a Mach 0.8 aircraft that was 20% more fuel efficient.  Hence the 787, which is small enough to be point to point, rather than hub to hub like the A380.

Well, if you use just the RP-1 without the LOX (ie. high-mach ramjet like RanulfC said) then your fuel costs are closer to existing airliners, although obviously still much higher, since you have to burn much more at lower efficiency.

Actually the LOX, although more than twice the mass, is less than 10% of the cost. LOX is dirt cheap, around $100 per ton in bulk.

Ramjets can be quite efficient. Far more so than a rocket. They use exterior air as reaction mass as well as oxydizer.

Hypersonic flight is always going to be many times the cost of high sub-sonic flight. Most people are not willing to pay that premium to cut their transit time by 40-50% (when you include time spent in transfers, check-in & customs)

[sanman]

The major airliner maunfacturers have looked at that many times, but concluded there wasn't a market. In 2001 Boeing announced their Sonic Cruiser, which would fly at Mach 0.95 to 0.98, 15-20% faster than regular airliners, while being just as fuel efficient. The airlines said they would rather have a Mach 0.8 aircraft that was 20% more fuel efficient.  Hence the 787, which is small enough to be point to point, rather than hub to hub like the A380.

Look, Boeing and Airbus are in the business of selling thousands of aircraft, and not in the business of pushing the envelope to sell just a few. What's required is a smaller, higher-end company that will make just a small number of vehicles which would then have free reign over that high-end niche market.

if a Concorde successor were in existence today, it could thrive in its niche market, provided that it managed to address some of the deficiencies of the original - noise pollution, fuel consumption, and low passenger capacity. A successor should have at least double the passenger capacity of the original, and address the noise pollution problem, perhaps by flying higher.

If Mach-3 passenger carriers could be designed a half-century ago, I would hope that by now technology could come up with something that can fly faster, quieter and more efficiently.

Actually the LOX, although more than twice the mass, is less than 10% of the cost. LOX is dirt cheap, around $100 per ton in bulk.

Ramjets can be quite efficient. Far more so than a rocket. They use exterior air as reaction mass as well as oxydizer.

Hypersonic flight is always going to be many times the cost of high sub-sonic flight. Most people are not willing to pay that premium to cut their transit time by 40-50% (when you include time spent in transfers, check-in & customs)

There will be niche markets that can sustain a certain minimum demand.
The world is big enough for that.

If world markets can support the construction of luxury cruise ships with ever fancier and expensive amenities, or ever taller skyscrapers with fancier architecture, then there's a market for faster transport aircraft.

A suborbital vehicle could still offer passengers the momentary once-in-a-lifetime thrill of space tourism, for which they might be willing to pay that extra premium cost.

[RanulfC]

I have another question for RanulfC or anyone else - would hypersonic flight produce enough shockwaves to be heard on the ground? That's one of the things that hurt Concorde, so that's why I'm asking. Let's assume a waverider as the worst scenario.

FYI, as long as you're flying over 100,000ft the sonic boom doesn't touch the ground

Look, Boeing and Airbus are in the business of selling thousands of aircraft, and not in the business of pushing the envelope to sell just a few. What's required is a smaller, higher-end company that will make just a small number of vehicles which would then have free reign over that high-end niche market.

Actually... That was the entire POINT of the "sonic-cruiser" design, faster service for a little more fuel but fewer passengers. The airlines said thanks, but no thanks. Of course that wasn't as fast or as far as we're discussing but to make money it has to be both economic to design, test, and operate.

You might want to keep in mind that "sub-orbital" (ballistic and/or skip-glide) passenger travel has been "just-around-the-corner" since the mid '40s.

As addressing the various issues with supersonic travel the technology is there for fast, fuel effcient flight it's just that supersonic aircraft don't lend themselves well to high-capacity shapes. The "Oblique-Wing" flying wing airliner MIGHT have been such a vehicle but outside of DARPA no one is willing to work on the design beyond scale models so we may never know for sure. As it is, airlines can get much more profit out of a subsonic 747 than a supersonic aircraft with half the passengers.

About the only added value an ICBPV (Inter-Continental Ballistic Passenger Vehicle) would have is the possibility of some "free-fall" time during the trip and the passengers getting astronaut wings. But that isn't going to be enough to interest large investment all by itself.

Having said that:
Well, hopefully Virgin/Branson will see enough demand to give a solid answer.

Sanman wrote:

But I noticed that Branson had commented early on about the idea of using SpaceShipTwo for quick intercontinental travel. Obviously it's not designed for that. But it then makes me wonder if a flashy-yet-conventional enterprise like his would have more eagerly leapt at the idea of a rapid intercontinental transport over a space tourist vehicle.

"Virgin Galactic" (noteably NOT Branson) said that SS-3 would originally have been the P2P vehicle, while later it has been said that SS-3 would be an orbital vehicle. Branson I've noted has a tendency to address mix and match the markets depending on who and where he's talking so I'm not sure at this point if P2P has anything to do with his plans.

kkattula wrote:

Hypersonic flight is always going to be many times the cost of high sub-sonic flight. Most people are not willing to pay that premium to cut their transit time by 40-50% (when you include time spent in transfers, check-in & customs)

If world markets can support the construction of luxury cruise ships with ever fancier and expensive amenities, or ever taller skyscrapers with fancier architecture, then there's a market for faster transport aircraft.

A suborbital vehicle could still offer passengers the momentary once-in-a-lifetime thrill of space tourism, for which they might be willing to pay that extra premium cost.

This isn't that cut-and-dried unfortunatly. Cruise ships are 5-star hotels that move between points of interest on the ocean. Their market is well understood and point-of-fact they could (and often do) stop nowhere and STILL make money just from the on-board experiances offered.

Skyscrappers leverage efficency by allowing a higher density of use of already expensived land.

Neither has anything to do with the operations of or possible markets for suborbital vehicles.

Suborbital "tourism" is an hour long experiance wrapped up within a two-week stay at a luxery hotel. Attending "training" classes and such is just an excuse to offer similar "experiance" additives based on the overall "theme" that you are going into "space" but actually are added costs to operations and maintenance that are not associated with the vehicle or its operations. Hence they drive already high prices higher even if the vehicle is somehow less costly to operate than a normal aircraft. (Not a given at this point)

Outside of that SINGLE "niche" market no economical business plan has been advanced that nails down a diffinative incentive capable of sustaining a supersonic, hypersonic, or suborbital fast intercontinental cargo or passenger vehicle.

It is not at all clear that there is any "incentive" for the "experiance" of space flight outside of the "tourism" market and what historical examples of transportation trends we have says that people won't pay "extra" for JUST the thrill connected to a new form of travel unless there is "added" experiance in some form or fashion. People pay more to get where they are going faster, yes, but only to a point and that point is far short of the difference between a ticket on a 787 and the cost of a ticket on a faster vehicle.

Does this mean that the idea of an intercontinental suborbital transport is never going to happen? Not at all, but we have yet to even prove that suborbital transport of ANY kind is economical at all, let alone comparable with "normal" transport methods.

Right now there are people moving towards showing that operations and maintenance of rocket powered vehicles has reached a point where they can be cost-competative in operational use. Once that is established it should be easier to either "down-grade" an orbital vehicle or "up-grade" a suborbital one to offer P2P type services, but the operations, maintenance and other aspects of proving something is "transportation" grade ready to go is not there yet.

At a "guess" (on my part) one or more of the "suborbital" launch companies that are currently working on "booster" models can modify their vehicle to carry cargo/passengers or someone will take an actual Reusable Booster vehicle and refit that to meet the P2P market. But it won't happen before it has been established that such vehicles can fly often and without large operations and maintenance budgets.

Randy

[93143]

The Reaction Engines A2 is supposed to do Brussels to Sydney in around four and a half hours (top speed of Mach 5) for a ticket price of €3940 (2006) if the hydrogen is produced by electrolysis.  The price is cut in half if steam reforming is used instead, indicating strong sensitivity to fuel costs and thus relatively cost-effective hardware design.

This is according to REL themselves.  I am not aware of an independent review confirming these numbers, but the Skylon business plan was recently subjected to such a review and passed with flying colours...

The problems with Concorde are avoided by having antipodal range and good subsonic performance coupled with much higher top speed.  The ability to go anywhere in the world at up to six times the speed of a modern airliner might be worth making the leap, where the ability to do transatlantic routes at two and a half times the speed of a modern airliner isn't.

EDIT:  I know the A2 is only tangentially related to the thread topic, but it was mentioned, and dismissed rather casually I thought...

[kkattula]

The Reaction Engines A2 is supposed to do Brussels to Sydney in around four and a half hours (top speed of Mach 5) for a ticket price of €3940 (2006) if the hydrogen is produced by electrolysis.  The price is cut in half if steam reforming is used instead, indicating strong sensitivity to fuel costs and thus relatively cost-effective hardware design.

This is according to REL themselves.  I am not aware of an independent review confirming these numbers, but the Skylon business plan was recently subjected to such a review and passed with flying colours...

The problems with Concorde are avoided by having antipodal range and good subsonic performance coupled with much higher top speed.  The ability to go anywhere in the world at up to six times the speed of a modern airliner might be worth making the leap, where the ability to do transatlantic routes at two and a half times the speed of a modern airliner isn't.

EDIT:  I know the A2 is only tangentially related to the thread topic, but it was mentioned, and dismissed rather casually I thought...

Which sector of the market is going to pay that much?

Backpackers?  They would rather spend the money on hugely extending their time in Australia.

Families on holiday? They want the lowest cost flights to leave more money for accomodations and entertainment.

Business travelers? Only the highest executives' time is worth the added cost.


The market is basically the same one Concorde catered for: VIPs, the ultra wealthy, and people wanting a once-in-lifetime experience.

[alamo]

kkattula : "The market is basically the same one Concorde catered for: VIPs, the ultra wealthy, and people wanting a once-in-lifetime experience."

and people for whom time is really precious, and are willing to pay gold for it ..
question of the right size
plan to build a supersonic "bizjets", the world has an incredible amount of


http://www.tupolev.ru/images/Pictures/CivilProject_Planes/Tu-444/Tu-444_4.jpg

for not long time no longer, will exist actually

http://startelegram.typepad.com/sky_talk/2007/11/aerion-takes-fi.html
probably find that they are slow, then ...

[RanulfC]

Actually? The original "two-person" (no cargo) ROTON was designed from the start as an SSTO vehicle. It was only when it grew bigger that it lost the SSTO ability and started having heavier issues.

I don't see any reason it wouldn't work.

I remember reading that "2 guys and a ham sandwich" slogan for original Roton, but I recall the original design also had other hangups, like trying to position the rocket combustion chambers on each of the rotor-tips, etc. That seemed a little weird and eccentric. When they switched to the FASTRAC engine, that seemed more mainstream and sober.

Well the original rotor-rockets was part and parcel of the efficiency and technically there weren't any issues with building and operating rockets that way.

The only "hangup" was that the design didn't scale well due to rotor scaling. That's why they had to go with the rotating rocket engine, (again doable, but at that time they were running out of money and needed to scale back engine development in favor of getting something flying) since at the scale for satellite deployment they needed an additional rocket boost-engine in addition to the rotors/rockets so they decided to just make the rotors a passive landing system and go with the rotating rocket engine. Announcing they were going to use the NASA developed FasTrac engine was business smart, but since NASA never really got the FasTrac development program up and running the point was moot.

The "rotors-on-top" design was a compromise at best given how unstable a top-mounted rotor design is under-power. It was pretty much a given that the "flight-test" vehicle was going to be unweildy and dangerous, but the top-rotor design gives a higher stability during un-powered (auto-rotation) descent.

Having discussed it with Bevins/Hudson and through my own research I'd have probably gone with starting out simply demonstrating SSTO capability with a smaller ROTON. I'd have gone with the more stable-under-power bottom or mid-mount rotor and low-or-mid-mount cabin.

Aggressive rotor positioning control and throttleing would be needed to stay below Mach-1 until after you passed 80Kft, and I'd have backed off the rotor speed at take off as the planned speed would have required some active and hefty sound suppression since the rotors would be close to or exceeding Mach-1 under full power prior to take off.
(I've thought it might be even a good idea to apply swept "unducted-fan" scimitar type airfoils for the rotors but they probably wouldn't give the same braking effect as would be needed)

Then again, I see type of vehicle as a way to go about "barnstorming" suborbital and "space" access being easily usable as a self-recovering booster stage even if you can't quite make SSTO with it.

If you can do SSTO with "2-people-and-a-ham-sandwhich" then you have an even better start on demo-ing operations and maintenance costs coupled with a high(er) flight rate that is going to be needed to prove out the various assumptions that have been made concerning reusable launch vehicles.

The small size of the payload (being generous, a "man-and-sandwhich" would probably only come up to around 200-250lbs of payload-to-orbit) commercial viability is probably marginal if it exists at all, but its quite possible IF the rest of the "RLV-assumptions" work out economically.

Flying a ROTON type vehicle out of county-state fairs is quite possible even if you don't manage to get fully into space from them the overall operability and general public access would be a tremendous boost in and of itself.

And of course I have a firm belief that such a vehicle, modular and able to be configured for various staging and velocity increments would easily match the Marine SUSTAIN program goals. So "I" personally have a lot of hopes for the vehicle type. Now... Getting someone to lend me the money to TRY this stuff... That's another story

Randy

[RanulfC]

EDIT:  I know the A2 is only tangentially related to the thread topic, but it was mentioned, and dismissed rather casually I thought...

Nope it's actually "on-topic" since practically any type of transportation is "technically" a "Single-Stage, Sub-Orbital" Intercontinental Transport

However, we should note that the major direction is something that actually leaves the atmosphere in general if not specific

alamo; The problem with any of the currently proposed supersonic business jets is still the same. Note that Aerion "took" its first order in 2007, as of 2010 they still had not fully developed or flight tested their aircraft and are in fact far short on the money to do so. The Japanese SSBJ project has government funding but even so it's not at all clear there will actually be enough buyers to justify production of an aircraft.

Hundreds of studies done in the last 40 years SAY that there is a market for supersonic travel, but the reality hasn't been proven. A 3-hour savings in time for NY to Paris, 41 minutes saved coast-to-coast across the USA, @5-hours saved on trips to Asia, so far NONE of that is important enough in the business world to justify the extra costs involved. So far the majority of orders is from the Middle-East which is most certianly NOT indicative of actual interest!

Now if a trip from NY to Paris takes less than an hour in transit, that's something else. Likewise going from coast-to-coast across the USA in under an hour, or a little over two hours to Asia, NOW you're talking enough time savings to pay for. But only up to a point and it is a VERY, very fine point! Anything under 2000miles is probably not viable no matter how little it costs as your time in and around the airports exceeds your flight time bay a factor of at least two. The problem is it probably WON'T cost "little" but a lot as supersonic and hypersonic aircraft are NOT built the same as standard aircraft and they don't carry as much cargo or passengers as subsonic aircraft. A business jet that CAN go supersonic but is only used at high subsonic speeds for flights around the US has a lot of added capacity and costs that are part of the overall maintenance and operations costs but are never fully re-cooped over the airframe lift time unless you charge much higher rates. And saving "about-41-minutes" is just not going to justify the extra expense.

Overall there was a LOT of misconceptions and false-assumptions (albeit, mostly based on pretty sound "forward-thinking" but rapidly dated information and possibilities) on things like advanced transportation. One could ask why "Intercontinental Mail Rockets" were never put into operation! (That's a bit of a "trick" though as they WERE, the "mail" they were designed to deliver consisted of nuclear weapons though

The "Mail-Rocket" was obsolete before it ever got off the drawing board, doomed by a telecommunications revolution that rapidly followed the on-set of the space-age.
Example:
http://blog.modernmechanix.com/2008/04/15/mail-via-rocket/
"Mail via Rocket!"

Predicting Rocket-Mail in by 1965, or in less than 10 years! A classic business case doomed by the invention of the fax-machine! Safety? We don't need no "safety" around here, I mean look at the "loading" crew high up on the side of the rocket as the one next door blasts-off!
(Yipe!)

The discovery of the Van-Allen belt(s) put a damper on enthusiasm for Intercontinental Ballistic Passenger Transport, the coffin lid was pretty much nailed shut by the combination of costs surrounding rocket vehicles and the extreme difficulty of telling if a dozen flights were being launched from the US/USSR carrying paying passengers or a cargo of H-Bombs.
Example:
http://blog.modernmechanix.com/2008/06/06/coast-to-coast-in-40-minutes/
"Coast-To-Coast in 40 Minutes!"

"300 miles up at 2-miles per second" (So you can spend time deep within the Inner Van Allen belt? )

Note the ship reenters somewhere over Illinois and pull into a gliding flight around 25 miles up. So far so good but look at that again, because somewhere just over the Rockies they are going to be doing around Mach-4 right over 'Vegas and well below 100,000ft. Second or third time casino's on the strip have to replace glass and you just KNOW what's going to happen to the company that runs the rocket planes don't you?

And you might want to recall that the oft mentioned but little detailed "rocket" motors are going to be similar to those used on the Atlas or Delta launch vehicles. Now where are you going to launch THAT from in or around New York? LA? Chicago?

While there are still a lot of assumptions involved in projecting a market for such services today, the very basic fact remains that a lot of the basic costs of "space" flight remain far higher than any comparable aircraft price point. And that more than anything else is what has yet to be addressed.

Early enthusiasms, rhetoric, hopes and dreams are all well and good in their place, but we've moved beyond that one would hope and so we need to set out sights on finding a REAL business case and coming up with the facts and figures to back them up. Then we'll really be on our way....

(Not that I'm NOT going to still be enthusiasticly spewing rhetoric, hopes and dreams all over the forums if given a single chance. Ye have been warned! )

Randy

[tnphysics]

I can see only one market: business travel. The military might be willing to pay for a rapid global deployment capability, but the massive network of bases around the world probably makes it unnecessary.

The problem is that such business executives must be able to go where they need to go, when they need to go. Thus, they cannot be batched. A hypersonic business transport would most likely need to be small, capable of being where and when it was needed. More like a fast business jet than the Concord.

[mmeijeri]

What did the military want TAVs for? I can imagine very rapid transport of special forces teams and their equipment might be useful in some circumstances.

[alamo]

RanulfC : "A 3-hour savings in time for NY to Paris, 41 minutes saved coast-to-coast across the USA, @5-hours saved on trips to Asia, so far NONE of that is important enough in the business world to justify the extra costs involved."

I say to.. probably find, that they are slow, then ...
and evolution "biz jet", of anything faster mach 3,4,5,  will require a large money

"Predicting Rocket-Mail in by 1965, or in less than 10 years! A classic business case doomed by the invention of the fax-machine!"

..and internet, and teleprezentation..

all in full agreement
In addition to this:
"Safety? We don't need no "safety" around here, I mean look at the "loading" crew high up on the side of the rocket as the one next door blasts-off!"

VTOVL-SSTO is potentially more secure than any airliner,
if the cabin "top", can be added LAS

[aero]

, @5-hours saved on trips to Asia,

As one who has made that trip several times, I can assure you that if, after about 10 hours outbound, airline cabin crews offered a supersonic upgrade option for the return flight, they would overbook every time.

[93143]

The Reaction Engines A2 is supposed to do Brussels to Sydney in around four and a half hours (top speed of Mach 5) for a ticket price of €3940 (2006) if the hydrogen is produced by electrolysis.  The price is cut in half if steam reforming is used instead

Which sector of the market is going to pay that much?

I just did a search for Sydney-to-Brussels first-class and business-class tickets.  The cheapest one I found was just under €6000.

A more permissive search on a specific day (Jan. 31, 2011) ranged from about €1300 (economy class, two stops) to over €9000...

Assuming REL's economic analysis is sound, either steam reforming of natural gas or cheap Polywell power for electrolysis could easily drop the ticket price on an A2 below $3000, which is actually quite reasonable for a fast trip to the other side of the world.  I once paid $1300 for an economy-class round trip halfway across Canada...

[Celebrimbor]

The energy requirements to go intercontinental may be similar to what's required to achieve orbit. But the market demand for rapid intercontinental transport will likely outpace demands for orbital satellite launches for quite some time.

Optimized economics trumps optimized physics.

You make an important point. My question is, where does your confidence in the market come from? I can't think of many items that need to be shipped this quickly. Since this was the starting point for the thread, lets keep it on physical objects other than people for the time being...

* With computers, the Internet and even rapid prototyping you wouldn't need to send an "idea" in this way.
* Aid, medical supplies etc. can almost always be procured relatively locally and flown in by aircraft.

What non-human payloads are you imagining?

EDIT: spelling

[Celebrimbor]

Lets remember that flight time is not the only factor. Suppose I work in London for a large company and I need to send a package to Tokyo as fast as possible - no expense spared.

Presumably the service would be set up to launch rapidly, on demand from a small selection of locations around the world. Suppose for the sake of argument, the nearest launch pad is in Stuttgart in Germany.

So I need to fly the package to Germany on the next available flight. While the package is en route, I can procure the services of the launcher and have it ready to go when the package arrives in Stuttgart - but I will need to rely on the usual airmail system to begin with.

Point is: unless I happen to start in Stuttgart, its not going to be less than an hour to Tokyo... more like a few hours. This limitation will eat into market demand somewhat...

[Cinder]

Wouldn't such potential benefits be enough to attract national interest in building that "pad" infrastructure?

[Celebrimbor]

Wouldn't such potential benefits be enough to attract national interest in building that "pad" infrastructure?

Its the potential benefits that I am calling into question...

However, assuming that there was a clear case, it would doubtless begin on an international level. i.e. there would perhaps be a European "pad" and a couple of US ones.

Two questions:
* What business would you have to be in to be worth basing your operations near such a pad for ease of access?
* Would the service still be useful (worth the money) if the nearest pad was 4 hours away?

[RanulfC]

I can see only one market: business travel. The military might be willing to pay for a rapid global deployment capability, but the massive network of bases around the world probably makes it unnecessary.

mmeijeri wrote:
What did the military want TAVs for? I can imagine very rapid transport of special forces teams and their equipment might be useful in some circumstances.

tnphysics; The military IS an applicable market, partly because there is no longer a "massive" network of overseas bases to mobilize from.

mmeijeri; Yes, rapid deployment of small forces is still a pretty high priority, especially given the current disadvantage I mentioned above.

The TAV though is much more than a single use item and the program was specifically directed towards small space reconissence missions, launch of, maintenance and repair of small military space assets, and global strike missions.

The RAND workshop/study report can be found here:
http://www.rand.org/pubs/monograph_reports/MR890.html

though there are a large number (if not the whole report) available in seperate chapters around the web. It's an interesting read none the less and quite informative on both the military and civil aspects of on-demand, small space access.

But on the whole the biggest issue is "aside" a government customer who would provide financing, but possibly demand sole-use options, there is no visible source for the development and production of higher speed civil aircraft. Partially this is because of the generally percieved "failure" of the Concord to be commercially viable. True or not, and regardless of what circumstances lead to that failure, the general perception, along with required high start up, development and production costs of higher speed aircraft has lead the industry to be less than enthusistic about high speed air travel.

It is hard to remember at times that airlines really are VERY conservative and do not like to take any chances if they can avoid it.

Now if someone actually proves out the underlying technologies and the airlines can see real facts and figures in place of assumptions and guess then they get interested.

The problem is that such business executives must be able to go where they need to go, when they need to go. Thus, they cannot be batched. A hypersonic business transport would most likely need to be small, capable of being where and when it was needed. More like a fast business jet than the Concord.

Actually they CAN still be batched, but in general you're correct that it won't help much with the costs on an individual basis. Companies that really need transportation tend to "batch" to afford on-demand aircraft, boats, and other means of transportation so it's not unheard of.

But it costs more to run a business jet than to run a large airliner due to both peronnel and infrastructure savings of the larger system. A hypersonic or suborbital system is not going to interface directly with those savings being more business jet like and less airliner like. Passing the extra costs down to the customer.

Randy
(Edit) Corrected formating... Which I still suck at but I'm workin on it

[RanulfC]

, @5-hours saved on trips to Asia,

As one who has made that trip several times, I can assure you that if, after about 10 hours outbound, airline cabin crews offered a supersonic upgrade option for the return flight, they would overbook every time.

You would probably be correct

However the airlines don't currently think so, which is the point I was making.
And having done the "old-fashioned" island hoping type trips there were times I personally longed to be on-board one of the many 14 hour "sardine-can-commuter" flights the military runs! On the other hand, after the "fare-well" party the night before I last left Korea I needed the time to recover before I got home! (And the thought of even attempting a suborbital flight after that gives me the shakes! )

Randy

[RanulfC]

The energy requirements to go intercontinental may be similar to what's required to achieve orbit. But the market demand for rapid intercontinental transport will likely outpace demands for orbital satellite launches for quite some time.

Optimized economics trumps optimized physics.

You make an important point. My question is, where does your confidence in the market come from? I can't think of many items that need to be shipped this quickly. Since this was the starting point for the thread, lets keep it on physical objects other than people for the time being...

* With computers, the Internet and even rapid prototyping you wouldn't need to send an "idea" in this way.
* Aid, medical supplies etc. can almost always be procured relatively locally and flown in by aircraft.

What non-human payloads are you imagining?

The most often quoted payloads are things like controller components, physical or mechanical primary components, or specialty low-failure items. Examples would be a production control board goes bad, of a valve or pump fails, things like that which shut down a high-value production or resource facility.

The argument goes that currently the facility is now sitting idle for X-amount of hours while a replacement is shipped via standard "high-speed" air shipment from a manufacturer. P2P fast-package deliver cuts that down to only a few hours versus the plant being shut down and un-productive for days on end.

Information has rarely been constrained by a standard "transportation" network, but those ideas have to be translated into a physical product at some point and that production often hinges in "single-point" failure prone production facilities. Since it is never cost effective to ensure you have a "spare" for everything, there are times when you are going to need to ship in a replacement part for one of those single-point-failure items. The issue is that no single company can afford to, likewise, bet money on financing a new transport segment and operations on the "chance" they will loose less money by spending what seems to be more money.

A million up front seems rather large money versus a possible cost of 10s of millions later down the road. A point that may or may never come about.

Taking your example, lets first NOT assume that the service is strictly "on-demand" since even couriers services will attempt to "bundle" as much as possible. But lets look at the "usual" travel time for you package via the standard "high-speed" system.
(Using a 767 freighter air craft: http://en.wikipedia.org/wiki/Boeing_767)

Your-office to a central packaging hub: 1 hour
Hub-to-Hub at Stuttgart: 1 hours
Stuttgart Hub packaging and manifesting: 1 hour
We will assume for a moment that there is an available flight and no wait time between getting the package processed, loaded and leaving Stuttgart.
Stuttgart-Hub to Tokyo-Hub assuming no stopovers: 11 hours
Tokyo-Hub unloading, processing, transhipment: 1 hour
Delivery: 1 hour

Total package time: 16 hours

This assumes of course that everything works out just right. USUALLY as long as the package arrives within 24 hours (local time at the location shipped FROM) is good enough, so 16 hours is actually pushing the system. Still...
Applying the standard "reasoning" from above, we'll say that the destination in Tokyo is a factory that goes "down" for a part only you can provide. Add about 5-hours to communicate the problem to you from Tokyo and find and package the part. Add another couple of hours for installation and "tweaking" of the part in Tokyo to get the factory up and running again, well say 2 hours.

We're at 23 hours right there, which in the world of international transportation, and repair services is down right fantastic. But for each hour the factory was 'down' it did not produce, lets say $10 million of product hence it "lost" $230 million over the time it was "down" from normal production.

Keep all the rest of the times factored in and JUST drop the Stuttgart-Hub to Tokyo-Hub time to 2-hours, or even 1. 14 to 16 hours, $140 to $160 million instead of $230 million.

"Worth" any cost? Probably not, especially not if YOU have to finance the development and operations of a new system to deliver the package. But if the system already exists?

This is actually pretty typical of MOST space access and transport discussions; The Chicken or the Egg? You need a market to develop a commercial transport system, but without a system the market remains stunted and can't raise the needed capital to develop. How do you develop the system without a market, or the market without a system?

The "normal" method is breaking the cycle with a large infusion of either demand or capital that does not depend on short-term payoff. This is usually government support of some type be it financial, assured market revenue, or something. And we're not seeing that so that leaves the private sector which is disinclined to pursue the issue, so we have limited progress and no investor confidence in an assured market.

Randy

[aero]

We're at 23 hours right there, which in the world of international transportation, and repair services is down right fantastic. But for each hour the factory was 'down' it did not produce, lets say $10 million of product hence it "lost" $230 million over the time it was "down" from normal production.

That's some high value product. $84 billion per year. I'd like to own a piece of that factory.

[Celebrimbor]

Thanks for the response. If you don't mind, I'll cut it down a little and reply piecewise:

Optimized economics trumps optimized physics.

You make an important point. My question is, where does your confidence in the market come from? I can't think of many items that need to be shipped this quickly.

The most often quoted payloads are things like controller components, physical or mechanical primary components, or specialty low-failure items. Examples would be a production control board goes bad, of a valve or pump fails, things like that which shut down a high-value production or resource facility.

The argument goes that currently the facility is now sitting idle for X-amount of hours while a replacement is shipped via standard "high-speed" air shipment from a manufacturer. P2P fast-package deliver cuts that down to only a few hours versus the plant being shut down and un-productive for days on end.

OK so I'll accept the premise that these objects exist and are necessarily produced at intercontinental distances.

Taking your example, lets first NOT assume that the service is strictly "on-demand" since even couriers services will attempt to "bundle" as much as possible. But lets look at the "usual" travel time for you package via the standard "high-speed" system.
(Using a 767 freighter air craft: http://en.wikipedia.org/wiki/Boeing_767)

Your-office to a central packaging hub: 1 hour
Hub-to-Hub at Stuttgart: 1 hours
Stuttgart Hub packaging and manifesting: 1 hour
We will assume for a moment that there is an available flight and no wait time between getting the package processed, loaded and leaving Stuttgart.
Stuttgart-Hub to Tokyo-Hub assuming no stopovers: 11 hours
Tokyo-Hub unloading, processing, transhipment: 1 hour
Delivery: 1 hour

Total package time: 16 hours

So the simple model is: X hours before intercontinental flight, Y hours in the intercontinental flight and Z hours after the intercontinental flight.

Scenario 1: Send package to nearest airport to source and fly direct to nearest airport to destination.

X is quite small, Y is quite big, Z is quite small.

Scenario 2: Send package to nearest airport to source and fly to nearest "pad", launch to ballistic and cruise to nearest airport to destination.

X is moderate, Y is quite small, Z is quite small.

In either case there will be an organisational overhead that is minimised by brute force of cash - small but existent.

Keep all the rest of the times factored in and JUST drop the Stuttgart-Hub to Tokyo-Hub time to 2-hours, or even 1. 14 to 16 hours, $140 to $160 million instead of $230 million.

My point is that not just Y drops, but X increases (unless you have made a long term decision to base the source close to a "pad").

"Worth" any cost? Probably not, especially not if YOU have to finance the development and operations of a new system to deliver the package. But if the system already exists?

This is actually pretty typical of MOST space access and transport discussions; The Chicken or the Egg? You need a market to develop a commercial transport system, but without a system the market remains stunted and can't raise the needed capital to develop. How do you develop the system without a market, or the market without a system?

Certainly not worth any cost. But we don't have to develop a market to do market research. It should be possible to evaluate the market size of your proposal to ship one-off tech parts this way.

If there is a strong potential market then, given the importance of location, governments would fall over themselves to develop (finance) it in their country (I'm thinking of Europe, read "states" if you prefer).

Other options also need to be evaluated that could well be more cost-effective.
* Factories that produce these parts could be distributed more strategically.
* Insurance could be taken out to cover eventualities.
* Probably others...

[mboeller]

somewhat unrelated to the discussion:

here are a few websites with informations about the original ROTON concept:

http://www.spacefuture.com/archive/the_roton_concept_and_its_unique_operations.shtml

http://www.wired.com/wired/archive/4.05/roton_pr.html  (print version)

http://stargazer2006.online.fr/space/roton.htm  (picture of one of the original variants half way down the page)

[93143]

But on the whole the biggest issue is "aside" a government customer who would provide financing, but possibly demand sole-use options, there is no visible source for the development and production of higher speed civil aircraft.

It wasn't REL that started the LAPCAT project.  Granted the ESA is a government organization, but the goal appears to be a civil airliner, not a force-projection system, so this doesn't appear to be a government customer situation.

I wonder if there's a philosophical case for considering a major technological capability or proof-of-concept to be public infrastructure...?  Certainly SpaceX (for example) would have gotten a lot less far on a lot more money if NASA and its contractors hadn't done the groundwork...

[A_M_Swallow]

So the simple model is: X hours before intercontinental flight, Y hours in the intercontinental flight and Z hours after the intercontinental flight.

{snip}

My point is that not just Y drops, but X increases (unless you have made a long term decision to base the source close to a "pad").

These days most cities have an airfield.  So a marketing requirement may be that the sub-orbital can land on a normal runway.

Take off will require a simple launch pad or normal runway.  Loading and refuelling will also need to be simple to add to existing airports.

[RanulfC]

We're at 23 hours right there, which in the world of international transportation, and repair services is down right fantastic. But for each hour the factory was 'down' it did not produce, lets say $10 million of product hence it "lost" $230 million over the time it was "down" from normal production.

That's some high value product. $84 billion per year. I'd like to own a piece of that factory.

I've also got a bridge for sale and some "prime" land in Florida that will soon (in a geological sense) be above water at a good price

Randy

[RanulfC]

somewhat unrelated to the discussion:

here are a few websites with informations about the original ROTON concept:

http://www.spacefuture.com/archive/the_roton_concept_and_its_unique_operations.shtml

http://www.wired.com/wired/archive/4.05/roton_pr.html  (print version)

http://stargazer2006.online.fr/space/roton.htm  (picture of one of the original variants half way down the page)

And another with a post-ROTON interview with Gary Hudson:
http://www.hobbyspace.com/AAdmin/archive/Interviews/Systems/GaryHudson.html

Some highlights:
-ROTON (as the ATV/"final" version) was actually a "stage-and-a-half" To-Orbit design but this wasn't actually "mentioned" anywhere at the time. (1.5STO)

-As noted the "original" ROTON design was a marginal-SSTO designed around people and small cargo only. The rotor-and-rockets effect gave enough increased ISP below 80,000ft to make the rotor mass on-orbit basicly "free" but once the payload demand got over about a thousand pounds to LEO the design no longer closed and a new approach was needed.
Instead, attempts were made to keep a majority of the "original" intent which caused design issues in and of themselves. Funding drying up with the loss of the target market was the major reason for shutting down but not the only one.

(I still agree with Gary on the achivement(s) of Rotary Rockets overall in production of flight level hardware within a year of starting)

There is some stuff I think that he takes a bit to "lightly" like the addition of "booster" rockets or a "zero-stage" to a marginal SSTO design. Anything that gets "dropped" off in flight has "issues" that effect operations and maintenance costs and they are NON-trivial!

For example, adding the "0.5" stage to the ROTON as small strap-on boosters would make it impossible to launch from pretty much anywhere but the Cape, and along with recovery and/or purchasing expenses for the SRBs that suddenly becomes a high level of restrictions on your operations. Part of the overall "draw" for the ROTON concept was "simple, bare pad operations" which adding the SRBs takes away.

It simply doesn't matter if you have a "new" or "inovative" operations plan, dropped-booster-rockets is already COVERED by current regulations and you immediatly put yourself under those regulations if you use "off-the-shelf" boosters.

Randy

[RanulfC]

But on the whole the biggest issue is "aside" a government customer who would provide financing, but possibly demand sole-use options, there is no visible source for the development and production of higher speed civil aircraft.

It wasn't REL that started the LAPCAT project.  Granted the ESA is a government organization, but the goal appears to be a civil airliner, not a force-projection system, so this doesn't appear to be a government customer situation.

Granted, however this situation is a "been-there/done-that" type in and of itself.

The US civil supersonic and high-speed transport government supported and funded trade and technology studies.

At issue though is the financial "support" in such cases is never going to be enough to activily develop and produce an operational vehicle. Both the French and British governments under-wrote a great deal of the development of Concorde, but in the end those same governments defaulted to commercial development and operations funding because there wasn't a firm 'reason' for government purchasing of the vehicle.

I wonder if there's a philosophical case for considering a major technological capability or proof-of-concept to be public infrastructure...?  Certainly SpaceX (for example) would have gotten a lot less far on a lot more money if NASA and its contractors hadn't done the groundwork...

Certainly there is! Look at the various developmental programs for aircraft, ships, submarines, oh you name a type of transportation and the government at some point used public funds to "show" it could be done. The major down-side here is that in general while a government program can SHOW something can be done, there is little or no incentive for such a program to show "it" can be done in an economical or commercially useful way

Supersonic travel, even hypersonic travel have been 'proven' by government programs, so has suborbital, orbital and interplanetary travel! But none of it's been done in a way that has proven "economical" commercially other than a few "niche" operations which are also (currently) government funded and supported due to government 'needs' in one way or another.

We have a lot of "theoretical" markets for orbital, and suborbital transportation, but only two (2) "proven" markets for orbital travel. Government payloads, and expensive commercial payloads both of which don't require a vehicle that has a high-flight rate or low cost operations.

Without added markets and/or commercial opportunities the current price-points won't come down and there will be no incentive for lower cost operations.

Randy

[DLR]

This thread is old, but I find it interesting to talk about this subject, so rather than starting a new one we can pick off where the others left.

On the economics of point-to-point intercontinental rockets:

The German Space Agency (DLR) is designing a spaceliner which is supposed to do just that. It's going to be a two-stage system with an "orbiter" and a reusable fly-back booster, both running on LOX/LH2. It is supposed to be able to make the trip from Europe to Australia in 90min.

http://www.dlr.de/en/desktopdefault.aspx/tabid-4530/3681_read-8344/3681_page-2/

In less than 90 Minutes from Frankfurt to Sydney – the DLR-Spaceliner

Die DLR study "Spaceliner" brings together the best from aeronautics and space: A flight from Europe to Australia with up to 50 passengers will be possible in less than 90 minutes. Even the calculated air fare rather corresponds to the price of an exclusive jet flight for the same distance, and therefore can not compete against tourist air fares, market analysts forcast a promising market of 700 Million Dollars per year for 15.000 highspeed travelers in 2021. The next step is to demonstrate the technologcial feasibility to be prepared for the hight speed connections in the future.

15.000 per year is not too shabby, it's about 300 flights per year. Not much, but maybe enough to be just profitable.

Since it's a two-stage system, it could serve as the basis for an orbital launch system as well, increasing synergies and market potential further.

[RobLynn]

Die DLR study "Spaceliner" brings together the best from aeronautics and space: A flight from Europe to Australia with up to 50 passengers will be possible in less than 90 minutes. Even the calculated air fare rather corresponds to the price of an exclusive jet flight for the same distance, and therefore can not compete against tourist air fares, market analysts forcast a promising market of 700 Million Dollars per year for 15.000 highspeed travelers in 2021. The next step is to demonstrate the technologcial feasibility to be prepared for the hight speed connections in the future.

15.000 per year is not too shabby, it's about 300 flights per year. Not much, but maybe enough to be just profitable.

$700 million pays for 350 $2million dollar skylon launches (projected long term cost I believe).  Skylon would have probably 20 tonnes payload for an antipodeal hop due to high L/D and lowered delta V requirement + probably eliminating payload bay and doors by building in a dedicated passenger compartment and eliminating or down-sizing some on-orbit systems.

20 tonnes should be able to cover at 150 passengers for a less than hour long flight, with maybe 1-2 medical crew aboard, no toilet or food etc.  You might even get more aboard as you are being charged $100/kg so you might opt for minimalism - webbing seat, no inflight entertainment and just buy everything at the other end rather than taking luggage.
 
Cost is around $15k per ticket, $30k return.  There would be a lot of takers at that sort of price - its only about 4 times a 1st class fare, and about the same price as concorde was ($10k return across the atlantic).

This really could be a very big market, once reliability is proven.

[apace]

Again some useless study to spend money. There's no business case for a 4h flight to Australia (don't forget the time to get to the airport, check-in, etc.) compared to the flight times we have currently. In modern business jets the time is not used useless, you can work, go to the internet, held conferences, etc... I just don't see the case where this works.

[Moe Grills]

Tell me, would it be feasible to design a sub-orbital vehicle that could serve the rapid intercontinental travel market?


As an engineering project: feasible.

As an economic viability: It's probably dead on arrival.
I'm ignoring the Skylon concept, since it is probably not
what you're referring to or suggesting.

ALSO!
If you do some surfing on the Net, you will find websites
suggesting the possibility of coast-to-coast 10,000mph tube trains (also called vacu-trains) that can take you from LA to NYC in less than an hour.
  Such a concept is theoretically feasible, so if that were ever built,. it would kill your idea.

[DLR]

It depends on the economics of your vehicle.

A first class ticket from Frankfurt to Sydney costs about 8000€ one-way, a business class ticket 3000€.

If your suborbital is able to offer flights in that price range, you've got yourself a lot of potential customers. I suppose many travelers who can afford it would be willing to pay even more (within reason) to have their overall travel time slashed from ~30hrs to ~4hrs (including security checks and transit).

The vehicle should ideally be single-stage, but that's probably out of the question for antipodal range if you don't want to use ramjets/scramjets. It should be able to take off and land on conventional runways and it should be able to be operated like an airliner, rather than a rocket.

A candidate for such a system would be Bristol Spaceplanes' spacebus. It's a two-stage system, with a LOX/RP-1 booster stage and a LOX/Hydrogen upper stage. For use as a "cheap" suborbital point-to-point transfer vehicle, the upper stage should probably use LOX/RP-1 as well. It would operate as follows: The whole thing would be integrated in Frankfurt, loaded with propellant and passengers. The booster stage would depart, use air-breathing engines to fly out over the North Sea, light its rocket engines, release the upper stage and return to Frankfurt (or perhaps Hamburg). The upper stage would finish the burn and skip-glide to Australia in 90min.



It would be designed to carry 50 people.

If the total operational cost spread out over a flight is no more than 5x or 6x the cost of the propellant, your 50 passengers would pay first class rates. If I remember correctly airlines roughly pay 2x or 3x times their fuel costs in maintenance and overhead per flight, if I remember correctly.

[apace]

It depends on the economics of your vehicle.

A first class ticket from Frankfurt to Sydney costs about 8000€ one-way, a business class ticket 3000€.

If your suborbital is able to offer flights in that price range, you've got yourself a lot of potential customers. I suppose many travelers who can afford it would be willing to pay even more (within reason) to have their overall travel time slashed from ~30hrs to ~4hrs (including security checks and transit).

The vehicle should ideally be single-stage, but that's probably out of the question for antipodal range if you don't want to use ramjets/scramjets. It should be able to take off and land on conventional runways and it should be able to be operated like an airliner, rather than a rocket.

A candidate for such a system would be Bristol Spaceplanes' spacebus. It's a two-stage system, with a LOX/RP-1 booster stage and a LOX/Hydrogen upper stage. For use as a "cheap" suborbital point-to-point transfer vehicle, the upper stage should probably use LOX/RP-1 as well. It would operate as follows: The whole thing would be integrated in Frankfurt, loaded with propellant and passengers. The booster stage would depart, use air-breathing engines to fly out over the North Sea, light its rocket engines, release the upper stage and return to Frankfurt (or perhaps Hamburg). The upper stage would finish the burn and skip-glide to Australia in 90min.



It would be designed to carry 50 people.

If the total operational cost spread out over a flight is no more than 5x or 6x the cost of the propellant, your 50 passengers would pay first class rates. If I remember correctly airlines roughly pay 2x or 3x times their fuel costs in maintenance and overhead per flight, if I remember correctly.

A soon as you work with a two stage system where in the first stage are no passwengers you will be always more expensive than with the current systems. Forget such concepts, you will never get the flight rate to get your prices down. No way.

[DLR]

The point is not to be as cheap as conventional airliners. The point is to beat them with much faster trip times, for which passengers can be expected (and will pay) a reasonable premium. 4hrs vs 30hrs is an advantage, especially for high-paying corporate passengers and VIPs.

And I don't see why two-stage shouldn't work. Treat the whole thing as a system. You have departure stages stationed in Sydney and Frankfurt and "orbiters" to travel in between. The German Space Agency certainly thinks such a system could be operated economically and they're even going for vertical launch at dedicated facilities (a bad idea in my eyes).

The best thing to get a high flight rate and prices down would be to use the first stage to launch reusable orbital spaceplanes as well as point-to-point suborbital services. Maximum commonality!

You can't dismiss it as uneconomical when such a system has never been operated before. In the 1930s, worldwide mass travel by the means of jet airliners was unthinkable as well, since jet engines had just been invented and were terribly unreliable and expensive to operate, very much like rockets today.

[apace]

You can't dismiss it as uneconomical when such a system has never been operated before. In the 1930s, worldwide mass travel by the means of jet airliners was unthinkable as well, since jet engines had just been invented and were terribly unreliable and expensive to operate, very much like rockets today.

If you run it as a two-stage system, you need additional pilots, additional runway time, additional installations at the airports, two first stages for every starting airport, etc.

Also if you run it as a one-stage system you need additional equipment for every airport because it requires complete different handling than normal airplanes.

It's the same as with the magnetic railways, the advantage of the speed is to less as it requires new railways.

To get such a system on the same price level as first or business class seats, you need hundreds of such airplanes and hundreds of flights every day.

[A_M_Swallow]

If you are flying between civilian airports think very, very, very carefully before using anything other than normal civilian aircraft fuel.  A special fuel means high costs and a limited number of destinations.

[Andrew_W]

The suborbital flight traveler from Europe to Australia will have to contend with less frequent flights, high g and zero g periods during the flight, and far worse jet lag, I suppose if there's urgent business in Australia at the start of a working day, our hero could just keep going as if it were the end of his day in his own European time zone, but he'd be unwise to keep working for 24 straight hours.

[balan h20]

Personaly I would never get in a tube train where I would be worried about tectonic plate shifting, volcanism, 4000 miles of tubes that can be a terrorist play ground, or a mainteniance nightmare, head on collisions, and a myriad of thousands of other things, when I could personally get on a plane and be weightless for a spell and see the curve of the earth and outer space. There is no choice in the matter outer space wins hands down.

[Spaniard]

A soon as you work with a two stage system where in the first stage are no passwengers you will be always more expensive than with the current systems. Forget such concepts, you will never get the flight rate to get your prices down. No way.

Well... It could be... A first stage that carry people, more slow, to different destination (near but on route) and a second stage only for ultrarapid travel.

[Downix]

Doing the math, $700 million per year with 15,000 passengers comes to $46k per passenger.

While high, there are passengers who do in fact pay more for tickets.

But the real advantage here is for cargo. 

[apace]

Doing the math, $700 million per year with 15,000 passengers comes to $46k per passenger.

While high, there are passengers who do in fact pay more for tickets.

But the real advantage here is for cargo. 

For cargo flights, every penny count. What type of cargo you think will need such a travel time?

[KelvinZero]

I think I can accept the argument that there is not the market based purely on shorter trip times (though those trip times certainly are a pain!)

However I think there is room for a constructive discussion here on how suborbital flights could be normalized by extending the application a bit beyond just a thrill ride. For starters if I were to spend a 100k or so for a rich mans thrill-ride for a few minutes of zero-g, ending the trip with a holiday somewhere you could clearly not have reached in that time by other means would add to the experience for me and I guess it would put me in a sort of very exclusive club. There are people rich enough to fly this way frequently. Maybe if it underscores their wealth and focus on progress it could make business sense.

Suborbital flights serve a purpose anyway. We might not be able to close the business gap with just one application yet but we only have to get up to several tens of flights before RLV begin making economic sense. If we can just get to that point then we will have continual progress that is not continually hamstrung by politics.

[M_Puckett]

Doing the math, $700 million per year with 15,000 passengers comes to $46k per passenger.

While high, there are passengers who do in fact pay more for tickets.

But the real advantage here is for cargo. 

For cargo flights, every penny count. What type of cargo you think will need such a travel time?

Human organs and critical parts where having a plant idled an extra day could cost hundreds of thousands of dollars.

[apace]

Doing the math, $700 million per year with 15,000 passengers comes to $46k per passenger.

While high, there are passengers who do in fact pay more for tickets.

But the real advantage here is for cargo. 

For cargo flights, every penny count. What type of cargo you think will need such a travel time?

Human organs and critical parts where having a plant idled an extra day could cost hundreds of thousands of dollars.

How large is this market? (The market which will be created by such a service, meaning that organs can be flight around the globe...)

[M_Puckett]

It would surely increase the pool of donors who could be mathed to reciepients.

[apace]

It would surely increase the pool of donors who could be mathed to reciepients.

So, let's count it for 0.5% of the flights... where are the other 99.5%?

[M_Puckett]

No law says you can't put other stuff on those flights.

[Andrew_W]

For cargo in most instances that short in flight time will count for nothing unless the flight is unscheduled, or there are so many scheduled flights that there'll be one when you want it.

[A_M_Swallow]

Scheduled fast flights are used for perishable items like cut flowers and fresh food.

[HMXHMX]

A huge problem with boost-glide suborbital transport is that the (uncertain) customs delay will always be longer than the flight.  It will largely negate the market value of being able to fly quickly.  Another issue is that, for antipodal journeys, you tend to arrive in the middle of the night, lessening the advantage for the business traveler markets.

The same sort of issue arises with the SUSTAIN concept that was mooted for rapid troop delivery.  Even though the insertion time might be two hours from the authorization to perform the mission, the practical realties of political decision making means that the leadership will dither for a day or two before giving the authority to proceed.  During that time, you could be flying your special forces to the drop zone in a subsonic B-2, and HALO dropping them via parachute from a special bomb bay personnel pod.

[space_man]

A huge problem with boost-glide suborbital transport is that the (uncertain) customs delay will always be longer than the flight.  It will largely negate the market value of being able to fly quickly.  Another issue is that, for antipodal journeys, you tend to arrive in the middle of the night, lessening the advantage for the business traveler markets.

The same sort of issue arises with the SUSTAIN concept that was mooted for rapid troop delivery.  Even though the insertion time might be two hours from the authorization to perform the mission, the practical realties of political decision making means that the leadership will dither for a day or two before giving the authority to proceed.  During that time, you could be flying your special forces to the drop zone in a subsonic B-2, and HALO dropping them via parachute from a special bomb bay personnel pod.

Good idea, but why not get rid of the B-2 completely. Have a simple one-stage hydrogen/LOX, deliver a "sardine can" of troops into suborbital space above enemy territory, from there the troops parachute to the surface. Make the rocket expandable, and the "can" expandable too.

[Jim]

Because it is not sleathy.  The can and rocket are going to impact near the target.  Also, there is the issue of getting out of the can

[mmeijeri]

Also, there is the issue of getting out of the can

Heh!

[kch]

Also, there is the issue of getting out of the can

Heh!

Easier said than done, sometimes:

http://news.yahoo.com/ferry-runs-aground-captain-stuck-toilet-152914917.html

[space_man]

Also, there is the issue of getting out of the can

Heh!

Easier said than done, sometimes:

http://news.yahoo.com/ferry-runs-aground-captain-stuck-toilet-152914917.html

issues with stealth? no problem! once the troops leave the can, the remainder of fuel can be used to crashland miles away from the site.

issues leaving the can? I dont think so, imagine the 6 minutes the booster spends in sub-orbit in 0-g, the troops, will open a hatch, float out into sub-orbit, deploy chutes to land.

[Jim]

issues with stealth? no problem! once the troops leave the can, the remainder of fuel can be used to crashland miles away from the site.

issues leaving the can? I dont think so, imagine the 6 minutes the booster spends in sub-orbit in 0-g, the troops, will open a hatch, float out into sub-orbit, deploy chutes to land.

What fuel?  This is a single stage.  Any ways, miles away is still to close.

Issues?  Yes, I think so.  Your idea is ridiculous and non viable.

A.  The crew would tumble out of control
B.  They would be subjected to entry heating
C.  And there might be g-loads

Any other make-believe  ideas that only work in movies?

[joek]

Beyond that, what design features would this market niche role compel?

Among others (good bibliography and references), see:
Point-to-Point Commercial Space Transportation in National Aviation System, FAA/DOT, Mar 2010

[space_man]

issues with stealth? no problem! once the troops leave the can, the remainder of fuel can be used to crashland miles away from the site.

issues leaving the can? I dont think so, imagine the 6 minutes the booster spends in sub-orbit in 0-g, the troops, will open a hatch, float out into sub-orbit, deploy chutes to land.

What fuel?  This is a single stage.  Any ways, miles away is still to close.

Issues?  Yes, I think so.  Your idea is ridiculous and non viable.

A.  The crew would tumble out of control
B.  They would be subjected to entry heating
C.  And there might be g-loads

Any other make-believe  ideas that only work in movies?

Fuel: Liquid hydrogen/Liquid Oxygen, plenty delta-v for an intercontinental manuever

A: That is false, apparently you know nothing about the 0-g flight through sub-orbit. At the apex, everything is very calm and the crew easily manuevers outside the hatch.

B: Entry heating? We are not going to orbit, merely sub-orbit, a pair of chutes will plenty sufficient for this.

C: what g-loads are you even talking about?

Any other make believe comments that only work on facebook?

[Andrew_W]

I think you'd probably want to have as stealthy a can as possible, and either land the can and then deploy the troops, or parachute the troops after the can had been slowed, whatever you do, I don't see how you avoid announcing your arrival with a sonic boom. 

[Jorge]

issues with stealth? no problem! once the troops leave the can, the remainder of fuel can be used to crashland miles away from the site.

issues leaving the can? I dont think so, imagine the 6 minutes the booster spends in sub-orbit in 0-g, the troops, will open a hatch, float out into sub-orbit, deploy chutes to land.

What fuel?  This is a single stage.  Any ways, miles away is still to close.

Issues?  Yes, I think so.  Your idea is ridiculous and non viable.

A.  The crew would tumble out of control
B.  They would be subjected to entry heating
C.  And there might be g-loads

Any other make-believe  ideas that only work in movies?

Fuel: Liquid hydrogen/Liquid Oxygen, plenty delta-v for an intercontinental manuever

A: That is false, apparently you know nothing about the 0-g flight through sub-orbit. At the apex, everything is very calm and the crew easily manuevers outside the hatch.

B: Entry heating? We are not going to orbit, merely sub-orbit, a pair of chutes will plenty sufficient for this.

False. See the "intercontinental" in the thread title? This isn't a simple up-and-back like SS1/2. The velocity required for an intercontinental suborbital trajectory is more than half of orbital velocity (shuttle needed ~18.4k to make a 3-out TAL, orbital is 25k). You *will* need a heat shield.

C: what g-loads are you even talking about?

Suborbital entries have substantial G-loads.

Any other make believe comments that only work on facebook?

Watch your mouth.

[go4mars]

Everyone is forgetting about the money brought in by the first stage passengers (who don't have to go as far). 

What non-human payloads are you imagining?

Oilfield parts.  There are many drill rigs and drill ships that cost hundreds of thousands of dollars by just sitting idle for a day while they wait for critical parts (and they are often located in fairly remote places).  Companies like Schlumberger could have a warehouse very close to the launch pad that has multiples of every tool in their line available for rapid delivery. 

The German Space Agency (DLR) is designing a spaceliner which is supposed to do just that. It's going to be a two-stage system with an "orbiter" and a reusable fly-back booster, both running on LOX/LH2. It is supposed to be able to make the trip from Europe to Australia in 90min.

http://www.dlr.de/en/desktopdefault.aspx/tabid-4530/3681_read-8344/3681_page-2/

Very cool!  But it says 2007, and there is no mention of development costs.  Would it be a lot less than reusable falcon/dragon?

Any other make-believe  ideas that only work in movies?

How about ejecting squished-up businessmen in mini re-entry capsules along the way?  Guy in a suit and tie, inside a spacesuit, which is wrapped in conical cork, legs up in the air (or cross-legged sit position but on his back), back laying on a 40" diameter heatshield, the spacesuit has a parachute (only to be used at low elevations).  After he has pulled the parachute and is away from the heatshield, detonate the heatshield apparatus so no large debris lands on anything.  He drifts to a park near the location of his meeting, drops the space suit, grabs a pita from a street vendor on his way in to his meeting.

[Moe Grills]

Doing the math, $700 million per year with 15,000 passengers comes to $46k per passenger.

While high, there are passengers who do in fact pay more for tickets.

But the real advantage here is for cargo. 

For cargo flights, every penny count. What type of cargo you think will need such a travel time?

Human organs and critical parts where having a plant idled an extra day could cost hundreds of thousands of dollars.

How large is this market? (The market which will be created by such a service, meaning that organs can be flight around the globe...)

It can certainly be part of the market. A mix of human traffic, mail, parcels, emergency engineering spare-parts, medical materials, etc., "that just have to get there the same day."

I'm starting to warm to the concept.

[MrAnthonyDR]

How about ejecting squished-up businessmen in mini re-entry capsules along the way?  Guy in a suit and tie, inside a spacesuit, which is wrapped in conical cork, legs up in the air (or cross-legged sit position but on his back), back laying on a 40" diameter heatshield, the spacesuit has a parachute (only to be used at low elevations).  After he has pulled the parachute and is away from the heatshield, detonate the heatshield apparatus so no large debris lands on anything.  He drifts to a park near the location of his meeting, drops the space suit, grabs a pita from a street vendor on his way in to his meeting.

I like this idea, however you missed one thing. The heat absorbed by the TPS on his capsule should be channelled into a small coffee maker, so that he has a fresh, piping-hot latte ready to pour when he lands.

In seriousness though, I would agree that the business model for P2P Sub-orbital travel would have to be drastically different from commercial aviation, which (lets be honest) more than suffices for 99% of the populations needs.

Human organs and critical parts where having a plant idled an extra day could cost hundreds of thousands of dollars.

How large is this market? (The market which will be created by such a service, meaning that organs can be flight around the globe...)

It can certainly be part of the market. A mix of human traffic, mail, parcels, emergency engineering spare-parts, medical materials, etc., "that just have to get there the same day."

I'm starting to warm to the concept.

Me too, this could be the market gap. However,putting my 'dragons den' hat on, we'd need to know how often on average these situations arise, and the current cost of resolving with existing aviation infrastructure, then compare to the cost to resolve with a sub-orbital solution, factoring in dev costs for return on investment.

When I think of it that way, I still think you'd need a whole lot more in the business case than that which has been mentioned already (oil refineries etc).

[john smith 19]

Tell me, would it be feasible to design a sub-orbital vehicle that could serve the rapid intercontinental travel market?

Yes. AS it has been since the mid 1960's, when Philip Bono described it.

So it would take off vertically, and land horizontally somewhere on the opposite side of the world. And it would be traveling through the vacuum in between.

Why this launch and landing mode? It requires that your vehicle be strong in *two* axes, rather than the one of HTHL or VTOL systems.

Imagine it being used only for cargo at first, but then much later it would eventually achieve a man-rating to allow rapid intercontinental passenger flights.

So the goal of this vehicle would not be to achieve orbit, but to provide rapid intercontinental suborbital travel/transport. We're talking about being able to land on the other side of the world in less than an hour.

Economics would dictate that this be a single-stage vehicle, for ease of turnaround.
Beyond that, what design features would this market niche role compel?

Your question could just be talking about a network of obsolete 2 seat M1+ fighter bombers (not quite as dumb as it sounds. DHL's core transport was at one time a group of executive jets acting as high value cargo carriers).
What I think you're talking about is generically called intercontinental ballistic transport.

Read Bono & Gatland "Frontiers of Space," articles in BIS "Spaceflight" 1968 (or 1967?) by Bono  and G. Harry Stine's "Halfway to Anywhere" for starting points.

I'll make a kickoff suggestion. Find out what high priority air freight prices are *now*, along with what Concorde fares were to get an idea of what people are prepared to *pay* for the reduction in time versus say sea freight.

Factor in that current airliner operating costs are about 3x to 4x the cost of fuel used.

Factor in that in the mid 60s (When Bono did an analysis) the fuel cost to orbit was roughly equal to the London to Sydney round trip fuel cost per unit of mass moved.

Now you've got some idea of what you need your vehicle to operate for per trip to make a profit.

BTW you'll need to talk the FAA (in the US) weather it's an aircraft (but rather an odd kind) or a spacecraft for carrying fee paying "Spaceflight participants."

Key questions are you going to be a builder/operator (Boeing did this in the 1930's, till they were broken up under anti-trust legislation. Possibly the best thing that ever happened to them) or just a builder, who can (in principle) sell to anyone who wants one.

[Robotbeat]

Bumping this. What is the efficiency of skip-glide? How much kinetic energy is conserved from the beginning of the bounce to the end? (I assume there's some sort of relationship to the hypersonic L/D ratio.)

[libra]

Some maths there... (scroll down a little).

https://www.alternatehistory.com/forum/threads/kolymas-shadow-an-alternate-space-race.314576/page-20

[Vahe231991]

I found this May 2023 news item in the Telegraph about the UK investigating the idea of an intercontinental suborbital passenger airliner:

Passengers will be able to fly from the UK to Sydney in less than two hours within a decade, according to new research.

The UK Civil Aviation Authority (CAA) is conducting studies into suborbital “Earth to Earth” space flights, which would see commercial aircraft exiting the Earth’s atmosphere to cut travel times to a fraction of what they are today.

Flying from London to Sydney for example, which usually takes 22 hours, could be reduced to just two hours.

With Elon Musk’s SpaceX, Jeff Bezos’s Blue Origin and Richard Branson’s Virgin Galactic already investing heavily in space exploration, the idea of affordable high-speed space transportation is no longer the stuff of science fiction.