Hypersonic suborbital transport market as SSTO enabler

[sevenperforce]

SSTO RLV proponents often argue that once a vehicle with rapid reuse potential exists, it would create the market which would enable it to be cost-effective. Unfortunately, it's doubtful than anyone will bother to build or design such a craft unless the market for rapid small-payload LEO launch already exists. This creates a chicken and egg problem, where the market won't exist until the launch vehicle does, and the launch vehicle won't exist until the market does.

It's possible, however, that a launch vehicle could be designed for a broader market, thus becoming available without requiring the rapid small-payload LEO launch market to exist first. From an economic/investment standpoint, it is much more attractive to build a vehicle which can use an existing market than it is to build a vehicle on the speculation that it will create a nonexistent market.

Such a market could potentially be realized in a similar way to how we first got into space: using the same vehicles for suborbital and orbital flights. The US and the USSR both figured out that the gigantic missiles they were planning to use to lob nukes on suborbital trajectories could, when properly staged, be used to boost payloads into orbit.

Many orbit-capable vehicles would make excellent hypersonic suborbital transports, suitable for transporting a large payload between any two points on Earth in an extremely short time. With a decent-sized fleet of such vehicles* servicing regular hypersonic transportation around the globe, you would have the support infrastructure necessary to service those same vehicles on orbital flights, either with reduced payloads or with a launch assist stage.

The question, then: does such a market exist? Is there a need for large cargo (or, on the other hand, passenger transport) to be whipped around the world in a matter of hours, regularly? Who would pay, and what is the probable market saturation?

*Skylon could potentially serve such a role, as it likely has excellent suborbital hypersonic flight capacities. It's not ideal, though, because it requires a great deal of LH₂.

 

[Kryten]

The market for supersonic air travel barely existed, so why would we expect hypersonic to be at all viable?

Edited April 22, 2016 by Kryten

[tater]

Yeah, it's all about price. Regular airliners currently fly well below what were normal cruising speeds in the 1960s to maximize fuel economy and keep costs low. Unless hypersonic can compete with current fare structures, it's a tiny niche market.

[Nibb31]

It's a clever idea, but I don't think such a market exists. 

For freight, air transport is already only really viable for perishable goods or parcels. Parcels spend more time in triage centers and trucks than they do on the plane. In most cases, logistics companies seek regularity and cost rather than speed. I don't think there are many cases where it makes a difference if cargo takes 6 hours to arrive rather than 24 hours on a regular plane route.

For passengers, the time required to get to the airport, go through customs and check-in also means that the difference between a hypersonic and a supersonic flight is negligeable.

 

 

Edited April 22, 2016 by Nibb31

[sgt_flyer]

Reaction engines tought about the concept - they are stating a 20000km range for their mach 5 concept. (so a way greater range than concorde's 6200km)

https://en.wikipedia.org/wiki/Reaction_Engines_A2

now such a design would face the same problem as supersonic jetliners - you can't go supersonic above the ground - clearly limiting the avaible destinations. one of their idea was to propose to go from europe to australia by flying over north pole then above the pacific.

i'm not sure making a plane for such specific routes is going to see much buyers for that plane they would likely prefer more classic and more flexible designs that can be affected to other routes

in addition, the airports that would receive such a plane would have to build and maintain the infrastructure for storing and fueling the LH2 (+ ongoing costs to maintain the cryogenic temperatures). that'll cost a lot for 1 plane ! especially given the low density of LH2 and cryogenics, you won't be able to use a fueling truck - you'd need to bring the plane to the LH2 tank instead.

Edited April 22, 2016 by sgt_flyer

[HebaruSan]

6 minutes ago, sgt_flyer said:

now such a design would face the same problem as supersonic jetliners - you can't go supersonic above the ground - clearly limiting the avaible destinations.

This might end up going nowhere, but allegedly NASA is awarding contracts to design planes with quieter sonic "thumps" instead of booms. I wonder whether you could put a SABRE engine onto such a fuselage/wing shape.

 

[p1t1o]

2 minutes ago, HebaruSan said:

This might end up going nowhere, but allegedly NASA is awarding contracts to design planes with quieter sonic "thumps" instead of booms. I wonder whether you could put a SABRE engine onto such a fuselage/wing shape.

Don't know of any reason why not, havn't heard of any funky aeronautical requirements of the SABRE. The only problem is that SABREs require a huge volume for their hydrogen fuel, you'd have to take most of the seats out that one.

If we are talking SABRE-powered hypersonics, would they not fly at significantly higher altitudes than most supersonic projects? Is there a chance that the sonic boom would be attenuated before reaching the ground?

[kerbiloid]

For charter flights - probably.

[tater]

This is another cart before the horse thing. Businesses exist to serve the needs and demands of consumers. There is certainly a demand for faster air travel, but that demand requires that the price point is roughly the same as the current price scheme. I doubt there is sufficient demand in the billionaire class for hypersonic aircraft past the corporate/charter level (it it's even justified for that).

[sevenperforce]

16 minutes ago, Nibb31 said:

It's a clever idea, but I don't think such a market exists. 

For freight, air transport is already only really viable for perishable goods or parcels. Parcels spend more time in triage centers and trucks than they do on the plane. In most cases, logistics companies seek regularity and cost rather than speed. I don't think there are many cases where it makes a difference if cargo takes 6 hours to arrive rather than 24 hours on a regular plane route.

For passengers, the time required to get to the airport, go through customs and check-in also means that the difference between a hypersonic and a supersonic flight is negligeable.

You really would want to go cargo, simply because the LV requirements are thus rendered substantially less onerous and you have a lot more flexibility. Unfortunately, I can't think of any suitable cargo either. There's really nothing in the world that needs to be shipped in bulk to the other side of the world in a matter of hours...at least, not so desperately that people would pay for a suborbital spaceflight to accomplish it. I suppose there are certain particularly expensive consumables with short lifetimes that could be harvested and shipped to high-end restaurants, etc., but the demand would not be high enough to be a major driver.

That leaves you with human cargo, with all its nasty "keep the cargo alive and air-conditioned" requirements. There's a glimmer of hope here, because while the difference between hypersonic and supersonic flight may be fairly low, supersonic options don't currently exist, and there is a big difference between hypersonic and subsonic flight. Subsonic flight means a trip to the other side of the world can take a day or longer; supersonic cuts this to several hours...suborbital hypersonic means no two points on the globe are more than an hour apart. There's a fair probability that the ability to commute around the world would prove attractive to enough people/businesses to service at least one or two routes from the start. I don't know what the maximum viable ticket price would be. 

Ideally, you could use existing airports by adding a dedicated spaceport terminal at lower cost than building an entirely new launchpad.

The suborbital/orbital transition would probably be accomplished by having some portion of the passenger cabin be replaceable with an extended fuel tank. E.g., you can take 30 people to the other side of the world in an hour for $90,000 each, or you can take 10 people to orbit for $350,000 each.

41 minutes ago, sgt_flyer said:

now such a design would face the same problem as supersonic jetliners - you can't go supersonic above the ground - clearly limiting the avaible destinations. one of their idea was to propose to go from europe to australia by flying over north pole then above the pacific.

Well, this is a suborbital spaceflight, not a high-altitude sustained hypersonic flight. With a steep ascent and re-entry trajectory, only two sonic booms reach the ground.

41 minutes ago, sgt_flyer said:

in addition, the airports that would receive such a plane would have to build and maintain the infrastructure for storing and fueling the LH2 (+ ongoing costs to maintain the cryogenic temperatures). that'll cost a lot for 1 plane ! especially given the low density of LH2 and cryogenics, you won't be able to use a fueling truck - you'd need to bring the plane to the LH2 tank instead.

LH₂ is a non-starter, I think. You need to be able to run on RP-1. Or LP/LNG at the very least.

That's not a bad thing. A high propellant mass fraction is okay...you WANT to be able to carry a lot of fuel...and high density means better T/W ratios and a smaller overall vehicle, which drives down vehicle reuse costs.

7 minutes ago, tater said:

This is another cart before the horse thing. Businesses exist to serve the needs and demands of consumers. There is certainly a demand for faster air travel, but that demand requires that the price point is roughly the same as the current price scheme. I doubt there is sufficient demand in the billionaire class for hypersonic aircraft past the corporate/charter level (it it's even justified for that).

Yeah, but the horse is a lot closer to the cart than the rapid-reuse-orbital-flight version.

[kerbiloid]

For "99%" airlines such plane means nothing but enormous spend of fuel.
So, only small amount of them is really required.
And while they are rare (i.e. probably always), their production cost will stay enormously high.
So, it's possible that some big and rich air company will use several of them for charter (i.e. irregular) flights or for VIPs.

[tater]

It's fine as long as there is a market such that it profits at the end of the day.

[kerbiloid]

Most of people would pay "1000 pieces of gold + 8 hours", not "10000 pieces of gold and 1 hour".

So, such plane won't have "economical class", even :business class". Only "first class".

[tater]

1 minute ago, kerbiloid said:

Most of people would pay "1000 pieces of gold + 8 hours", not "10000 pieces of gold and 1 hour".

So, such plane won't have "economical class", even :business class". Only "first class".

That's fine as long as it can actually pay for itself.

Right now, first class, nonstop from NY to Tokyo is about $20,000 round trip, and the random day I picked has 9 flights (kayak). There are 6 flights starting at 22k for today.

So there is already a market for ~$10,000+ seats (one way). The trick is to figure out if that is feasible. 

[HebaruSan]

12 minutes ago, sevenperforce said:

You really would want to go cargo, simply because the LV requirements are thus rendered substantially less onerous and you have a lot more flexibility. Unfortunately, I can't think of any suitable cargo either. There's really nothing in the world that needs to be shipped in bulk to the other side of the world in a matter of hours...at least, not so desperately that people would pay for a suborbital spaceflight to accomplish it.

Molybdenum-99 has a half life of 66 hours, has inelastic demand from hospitals for nuclear medicine procedures, and is shortage-prone (two reactors in the world make it, and the one providing 80% of the supply has been shut down twice in the last decade, and both are nearing end of life).

http://www.molecularimaging.net/topics/practice-management/quality/lessons-learned-moly-shortage-crisis-over?nopaging=1

While current transport methods are probably adequate for ⁹⁹Mo, maybe you could transport other industrially useful isotopes with shorter half lives.

[YNM]

1 hour ago, sevenperforce said:

Such a market could potentially be realized in a similar way to how we first got into space: using the same vehicles for suborbital and orbital flights. The US and the USSR both figured out that the gigantic missiles they were planning to use to lob nukes on suborbital trajectories could, when properly staged, be used to boost payloads into orbit.

All of it were capable of orbital flight - as long as the payload is correctly small. A guy sitting in a round tin doesn't weigh more than a few guidance computer with heavily protected nuclear missile in it.

Now, we don't even have a reason why should the things be soo small for the same rule to work. Better take the flight as secondary payload to normal sats.

Edited April 22, 2016 by YNM

[KerikBalm]

The only market would be military... and that's not a large enough market.

The US military in particular likes the concept of a prompt global strike (PGS or soemthing like that). I even saw a concept for a one way method to deliver a squad of special forces using some suborbital lifting body re-entry vehicle (somewhat like the X-33. Also I think it landed with a parasail and didn't need a large landing space).

They've considered ICBMs with "conventional" (chemical explosives) rather than nuclear warheads... but that's far too provacative given that most ICBMs are nuclear equiped (indeed, for an ICBM, nuclear is conventional) and every launch risks starting a nuclear war.

A hypersonic aircraft/missile would appear to be the solution (though well positioned railgun equipped ships could take care of a lot of stuff).

The military often likes to spend a lot of money to have a capability that it rarely if ever actually uses. A hypersonic special forces delivery vehicle may interest them... but extraction would be problematic...

Hypotheticall: a reusable system could have a hypersonic transport that slows down just enough to airdrop the special forces squad... maybe the forces have something like this to enable them to have enough crossrange capability to reach the target:

Then it accelerates and climbs again to proceed to a friendly airbase.

A second craft would be used for extraction...much slower because it will need to be able to fly much slower to extract the forces... possibly by skyhook.

https://en.wikipedia.org/wiki/Fulton_surface-to-air_recovery_system

Thats about the only viable use I can think of for it.... when you need to get something somewhere very fast... its probably because its a fleeting opporotunity to kill or capture an exposed target.

[sevenperforce]

4 minutes ago, KerikBalm said:

The only market would be military... and that's not a large enough market.

The US military in particular likes the concept of a prompt global strike (PGS or soemthing like that). I even saw a concept for a one way method to deliver a squad of special forces using some suborbital lifting body re-entry vehicle (somewhat like the X-33. Also I think it landed with a parasail and didn't need a large landing space).

They've considered ICBMs with "conventional" (chemical explosives) rather than nuclear warheads... but that's far too provacative given that most ICBMs are nuclear equiped (indeed, for an ICBM, nuclear is conventional) and every launch risks starting a nuclear war.

A hypersonic aircraft/missile would appear to be the solution (though well positioned railgun equipped ships could take care of a lot of stuff).

The military often likes to spend a lot of money to have a capability that it rarely if ever actually uses. A hypersonic special forces delivery vehicle may interest them... but extraction would be problematic...

The problem is that it actually has to be used in order to generate revenue.

32 minutes ago, HebaruSan said:

Molybdenum-99 has a half life of 66 hours, has inelastic demand from hospitals for nuclear medicine procedures, and is shortage-prone (two reactors in the world make it, and the one providing 80% of the supply has been shut down twice in the last decade, and both are nearing end of life).

http://www.molecularimaging.net/topics/practice-management/quality/lessons-learned-moly-shortage-crisis-over?nopaging=1

While current transport methods are probably adequate for ⁹⁹Mo, maybe you could transport other industrially useful isotopes with shorter half lives.

Intriguing. I wonder how large an average shipment is. Partial passenger/partial cargo is a possibility if there is some regular need...

[HebaruSan]

3 minutes ago, sevenperforce said:

The problem is that it actually has to be used in order to generate revenue.

Intriguing. I wonder how large an average shipment is. Partial passenger/partial cargo is a possibility if there is some regular need...

Each hospital typically receives about a briefcase-sized shipment per week, I believe. So it may only work for dense population centers where a large number of those shipments for different hospitals could be bundled together on the same flights.

[sevenperforce]

1 hour ago, HebaruSan said:

Each hospital typically receives about a briefcase-sized shipment per week, I believe. So it may only work for dense population centers where a large number of those shipments for different hospitals could be bundled together on the same flights.

Perhaps a regular hypersonic transport between two nodes carrying a series of time-sensitive cargo packages + passengers?

[kunok]

4 minutes ago, sevenperforce said:

Perhaps a regular hypersonic transport between two nodes carrying a series of time-sensitive cargo packages + passengers?

The problem is that probably it will be cheaper to make more reactors than an hypersonic transport... So the only option I think we still have is the military as @KerikBalm says, which makes me sad.

[PB666]

2 hours ago, HebaruSan said:

This might end up going nowhere, but allegedly NASA is awarding contracts to design planes with quieter sonic "thumps" instead of booms. I wonder whether you could put a SABRE engine onto such a fuselage/wing shape.

 

 

When runways are 5 to 10km in length, when you have more powerful weight and fuel efficient sub-Mach and Super Mach engine combos, then SST/HST is commercially possible.
The concorde was an accident waiting to happen, it had so many achilles heals relative to other commercial AC, many problems that concorde faced will face any SST. Sonic boom is not the biggest problem, going faster than Mach 1.5 presents all kinds of challenges, not the least of which is that super-Mach designs do not take off as easily as a Super-cub. Those designs require super long runways to safely take-off (something that the concorde never had). If you want to carry 200 passengers a 5 km runway is almost a necessity. In addition highly streamlined aircrafte need powerful lightweight engines that have high thrust to weight ratio. The reason is this, when the craft rotates to take off, its a combination of the sin(thrust) + lift that gets the craft off of the runway (plus ground effect for swept-wing). As the craft becomes more streamlined, the sin(thrust) is a more important component of the lift equation. Ground effect may get you off the ground, but it will not keep you off the ground if drag at takeoff = thrust. If your delta has turned up 20 degrees and your wing is near stalling, you need to nose down and still have enough thrust to gain both altitude and speed. Stalls are not due to airspeed but differential angle of attack, and the more streamlined the crafts wings the higher the angle of attack for any given take off speed. Therefore runway length is critical and engine peak performance at MSL are critical.

 

[wumpus]

If I was part of reaction systems, I would certainly want to go this route.  It might be a long shot, but I'm sure it is a long shot that has a better chance than straight to SSTO.

I vaguely remember a claim from rec.arts.sf-lovers (an ancient sci-fi forum to you youngin's) that suborbital flights to Australia used less power than supersonic flights to Australia.  Anybody know how to do these calculations?  And is it feasible to do a "bouncing in and out of the atmosphere" flight profile with only mach 5?

I'm sure that SABRE can use kerosene.  I'm less sure that such a plane makes sense for flights where the mass of kerosene might not be higher than the the dry mass of the plane.  LH2 might make more sense.  Obviously you need LH2 if you want SSTO.

While the military does like "prompt global strikes" and can certainly sell the beltway on that, I'm less sure about the rest of the USA wanting to pay for "another F35 program".  It seems much more likely that when (and only when) B-52s start falling out of the sky, Congress will approach Boeing and ask/tell them to make a 777 or 787 that can drop bombs.

Anybody have a guess at how many seats a SABRE-powered "airplane" would fly?  Certainly a lot more than Skylon...

[HebaruSan]

5 minutes ago, wumpus said:

Anybody have a guess at how many seats a SABRE-powered "airplane" would fly?  Certainly a lot more than Skylon...

747s used 4 engines with 200-300 kN each, so 800-1200 kN total. One SABRE supposedly has 1960 kN at sea level. I don't know how much capacity you lose by having to be hypersonic and vacuum-capable, but a naive ratio based on thrust would give 1633 passengers.

[sevenperforce]

15 minutes ago, wumpus said:

If I was part of reaction systems, I would certainly want to go this route.  It might be a long shot, but I'm sure it is a long shot that has a better chance than straight to SSTO.

I'm sure that SABRE can use kerosene.  I'm less sure that such a plane makes sense for flights where the mass of kerosene might not be higher than the the dry mass of the plane.  LH2 might make more sense.  Obviously you need LH2 if you want SSTO.

The SABRE engine cannot use kerosene, by definition, because it is an airbreather that requires you to dump LH₂ through a precooler.

But you wouldn't actually need LH₂ to get Skylon to orbit. Strengthen the frame, replace the SABRE engines with a pair of steel-ducted Merlin 1D clusters, and fill it up with kerolox. It would carry triple the payload to orbit. Mass fraction wouldn't be as good, but that doesn't really matter because kerosene is cheap as heck and simple to tank.

The proposed Skylon vehicle is REALLY big.

Edited April 22, 2016 by sevenperforce