egph
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Possible Supersonic Routes - Economic Viability

Mon Sep 28, 2015 9:23 am

Hey all,

So with the latest incarnation of the "Let's get Concorde back into the sky" story last week, it got me thinking about a hypothetical situation.

Leaving behind the intricacies and cost of either Boeing, Airbus or another manufacturer producing a new supersonic airliner. Would there be any routes which, should such an aircraft come on the market could be economically viable by selling it to premium business traffic? Would any of the Middle East 3 who weren't really on the scene when Concorde was doing the rounds take an interest in operating the aircraft?
 
sevenheavy
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RE: Possible Supersonic Routes - Economic Viability

Mon Sep 28, 2015 11:49 am

IMHO there are plenty of routes where a supersonic aircraft would be theoretically viable.

The thing is, its hard to guess the economics (fuel burn, mx requirements, size etc.) as Concorde is 4 generations too old to give much of a comparison.

Its fair to say that costs will be significantly higher than a subsonic jet. The question is how much higher. A supersonic aircraft has the advantage of being able to operate more sectors per day which could mean it could operate 2 round trips where other aircraft could only do one.

Routes from Europe to the Middle East and the U.S. could work if the operating costs were significantly lower than Concorde, although Middle Eastern flights operate over land which could be an issue.

Most airlines would probably be very nervous as the aircraft would likely be very sensitive to an oil price spike
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coolian2
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RE: Possible Supersonic Routes - Economic Viability

Mon Sep 28, 2015 12:32 pm

I can only imagine over water flights as I imagine any country you overfly would take a dim view on sonic booms
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MKIAZ
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RE: Possible Supersonic Routes - Economic Viability

Mon Sep 28, 2015 4:32 pm

NYC to Europe and maybe LAX-TYO.
 
B2707SST
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RE: Possible Supersonic Routes - Economic Viability

Mon Sep 28, 2015 6:29 pm

Although supersonic business jets with a low-boom design like Aerion might get away with overland flight, current technology doesn't seem to support a low-boom SST. Thus, the route network would be transoceanic, possibly with limited corridors over the very high arctic. Here are some possible routes:

Transatlantic
All the major US/Canada east coast - western Europe city pairs are in play, e.g. YUL-CDG, JFK-LHR, IAD-MAD, MIA-FRA. Inland quickly gets more difficult as prolonged subsonic operations are very inefficient. A pair like ORD-FRA would probably not support SST service.

Transpacific
These distances would often involve one or even two refueling stops. Direct routes with a quick stop may be feasible, but SST hubs that require plane changes are a major problem. Even a tight one-hour connection quickly erodes the time savings from supersonic flight, and travelers may well prefer a subsonic non-stop service over SST routes with even one connection. Greater range enormously improves the productivity of an SST, but keeping engine noise, takeoff weight, and fuel burn to acceptable levels are critical constraints.

Most recent studies target a range around 5,000 nm with a takeoff weight of approximately 700,000 lbs. Key SST fuel stops would likely include HNL, PPT, and GUM - for example, the routes below are all under 5,000 statute miles (except HNL-PVG, which is 5,069 miles).

Potential transpacific SST routes


Some of the routes shown may not be possible if boom corridors aren't available between inhabited islands (e.g. JKT-GUM).

Certain marginal routes (LAX/SFO-NRT) might be possible with 5,000 nautical miles of range depending on temperatures and winds aloft, which generally have less impact on SSTs than subsonics. One-stop service from the US west coast to Hong Kong and Manila via HNL would require closer to 5,500 nm of nominal range; Beijing would still be difficult due to the need to fly around Japan.

-B2707SST

[Edited 2015-09-28 11:35:38]
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Stitch
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RE: Possible Supersonic Routes - Economic Viability

Mon Sep 28, 2015 7:17 pm

Quoting EGPH (Thread starter):
Would any of the Middle East 3 who weren't really on the scene when Concorde was doing the rounds take an interest in operating the aircraft?

The ME3's location would likely only work for supersonic travel to maybe KUL, SIN and PER as they could traverse the Indian Ocean. Australia might loosen up overland restrictions for the Outback, but I imagine you'd still need to do a fair bit of the overland run to BNE/MEL/SYD at subsonic speeds.

Back in Concorde's day, the Shah of Iran did approve supersonic overflight of his country, but that didn't really help all that much when Turkey and India didn't.  
 
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DocLightning
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RE: Possible Supersonic Routes - Economic Viability

Wed Sep 30, 2015 8:37 pm

Any new SST would need to be designed in such a manner as to minimize sonic boom on the ground. There are ways to design the body such that the shockwaves interfere with each-other and thus is inaudible on the ground.

If that were the case, then any route would be available.

The trouble is that shaping the fuselage this way means a non-constant cross-section and that leads to issues with empty space and interior arrangements.
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LH707330
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RE: Possible Supersonic Routes - Economic Viability

Wed Sep 30, 2015 9:10 pm

Quoting B2707SST (Reply 4):
Certain marginal routes (LAX/SFO-NRT) might be possible with 5,000 nautical miles of range depending on temperatures and winds aloft, which generally have less impact on SSTs than subsonics. One-stop service from the US west coast to Hong Kong and Manila via HNL would require closer to 5,500 nm of nominal range; Beijing would still be difficult due to the need to fly around Japan.

One benefit of SST FLs is that there are typically only mild winds aloft, so that shouldn't be a big problem.

Quoting DocLightning (Reply 6):
Any new SST would need to be designed in such a manner as to minimize sonic boom on the ground. There are ways to design the body such that the shockwaves interfere with each-other and thus is inaudible on the ground.

If that were the case, then any route would be available.

That optimistically assumes that regulators lift the blanket bans now in place and replace them with "no boom louder than x" rules.

Quoting DocLightning (Reply 6):
The trouble is that shaping the fuselage this way means a non-constant cross-section and that leads to issues with empty space and interior arrangements.

...and hence weight. Maybe a few external fuel tanks will help fix the problem 
 
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Adipasquale
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RE: Possible Supersonic Routes - Economic Viability

Thu Oct 01, 2015 12:18 am

No routes. The internet has made any need for need for a supersonic airliner before disappear. If there was sufficient demand for a supersonic airliner after Concorde, it would have been built. Even Concorde did not sell nearly as many copies as originally projected as there is really not a huge market for supersonic flights.
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RE: Possible Supersonic Routes - Economic Viability

Thu Oct 01, 2015 8:16 pm

Quoting LH707330 (Reply 7):
That optimistically assumes that regulators lift the blanket bans now in place and replace them with "no boom louder than x" rules.

At some point, humans will need to shrink the world again. I refuse to believe that we will never travel faster than M=0.85.

But your point still is valid. The regulators will need some solid proof that the new fuselage shape will be essentially inaudible on the ground. That means that the aircraft will need to be designed and built for testing with no guarantee of ever being certified. That's a huge risk for any company to take, even a company with pockets as deep as A and B.

Quoting LH707330 (Reply 7):
...and hence weight. Maybe a few external fuel tanks will help fix the problem 

Tanks could be incorporated into the excess spaces in the fuselage. The trouble would be windows, then.

Quoting Adipasquale (Reply 8):

No routes. The internet has made any need for need for a supersonic airliner before disappear

Which is why the global air market has shrunk dramatically since 1996 or so when internet access became common?
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LH707330
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RE: Possible Supersonic Routes - Economic Viability

Thu Oct 01, 2015 9:25 pm

Quoting DocLightning (Reply 9):
At some point, humans will need to shrink the world again. I refuse to believe that we will never travel faster than M=0.85.

At what cost (in terms of time and comfort)? People will tolerate 10Y 777s in order to save a buck, many prefer 340s over 744s because they are quieter, though the 744 is faster. Maybe if oil stays cheap we'll see someone take a crack at it, but I think the risks are too high. There's ongoing debate about the viability of Boeing's NMA/MOM design, and that will surely sell more copies than a new SST, which will require ~$10B in airframe R&D as well as a risk-happy engine OEM willing to plunk down another $1-2B. Will the lie-flat J crowd tolerate Y-esque seats like Concorde had?

Quoting DocLightning (Reply 9):
But your point still is valid. The regulators will need some solid proof that the new fuselage shape will be essentially inaudible on the ground. That means that the aircraft will need to be designed and built for testing with no guarantee of ever being certified. That's a huge risk for any company to take, even a company with pockets as deep as A and B.

It's possible to design a cheap demonstrator, IIRC it's been done. Maybe some well-placed friends in government can help out with that ("We'll build this in your district if you nudge the FAA....").

Quoting DocLightning (Reply 9):
Tanks could be incorporated into the excess spaces in the fuselage.

I know, I was making a joke about the other thread.
 
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Adipasquale
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RE: Possible Supersonic Routes - Economic Viability

Fri Oct 02, 2015 2:48 am

Quoting DocLightning (Reply 9):
Which is why the global air market has shrunk dramatically since 1996 or so when internet access became common

Notice I said supersonic airliner.
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RE: Possible Supersonic Routes - Economic Viability

Fri Oct 02, 2015 4:29 am

Quoting Adipasquale (Reply 11):
Notice I said supersonic airliner.

Nobody enjoys sitting in a Y-class seat for 14 hours. The point of subsonic air travel is to get somewhere quickly. Supersonic air travel would get people there even more quickly.
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PlunaCRJ
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RE: Possible Supersonic Routes - Economic Viability

Fri Oct 02, 2015 3:44 pm

What about time zones?
I recall reading somewhere that trans-pacific SST, due to the time difference would mean either sub-optimal arrival or departure times, making the whole prospect unattractive, and negating any benefits from time savings.
 
ThirtyEcho
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RE: Possible Supersonic Routes - Economic Viability

Sat Oct 03, 2015 8:29 pm

The "race for speed" that dominated so much of early airline flying ended with the first generation jets. Essentially, travel times were cut in half by the 707 and that has, since the late 1950s, been all the speed anyone needed or wanted. Concorde was an anomaly that only served to prove the new reality, that long haul and ultra long haul was the new standard. That fuel stop on long routes, routes that should have been the supersonic forte, ate up the advantage of going Mach 2 in cruise. There was no great advantage in going really fast versus the advantage of going nonstop.

Stockholders and lenders are not going to tolerate the supersonic business jet in any corporate fleet. If that wasn't true, SSBJs would already be flying since there is no huge technological hill to be climbed in building such an airplane. Any CEO who pushes for such a thing is going to find themselves stuck through the heart by its needle nose. The only conceivable market for an SSBJ would be individuals who can write obscenely large checks and are answerable to no one.

The point made about the Internet's impact on corporate travel is a valid one. A packet of data travels free and at nearly the speed of light, allowing for slight system delays. Mach 2 seems more like the Pony Express in comparison. Many times, the users of corporate jet travel are lower level technicians who must be on site to do their work and not the executives in upper management. If a production line stops, you don't send the CEO or the CFO to fix it.
 
Viscount724
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RE: Possible Supersonic Routes - Economic Viability

Sun Oct 04, 2015 2:46 am

Quoting DocLightning (Reply 9):
Quoting LH707330 (Reply 7):
That optimistically assumes that regulators lift the blanket bans now in place and replace them with "no boom louder than x" rules.

At some point, humans will need to shrink the world again. I refuse to believe that we will never travel faster than M=0.85.

You can be almost anywhere in the world within 24 hours or slightly more now. That's fast enough for 99.9% of people. And the 0.1% who might be willing to pay a huge premium for supersonic travel aren't numerous enough to justify the huge development cost of a new supersonic airliner even if the sonic boom issue could be overcome.

[Edited 2015-10-03 19:47:42]
 
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Adipasquale
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RE: Possible Supersonic Routes - Economic Viability

Mon Oct 05, 2015 12:49 am

Quoting DocLightning (Reply 12):
Nobody enjoys sitting in a Y-class seat for 14 hours. The point of subsonic air travel is to get somewhere quickly. Supersonic air travel would get people there even more quickly.

But what is the cost people are willing to pay? A LAX-SYD round trip ticket costs about $1500. I assume most people would pay that for a 14-15 hour flight as opposed to at least double that for a similar supersonic flight.

Quoting ThirtyEcho (Reply 14):
The "race for speed" that dominated so much of early airline flying ended with the first generation jets. Essentially, travel times were cut in half by the 707 and that has, since the late 1950s, been all the speed anyone needed or wanted

Exactly.

Quoting Viscount724 (Reply 15):
You can be almost anywhere in the world within 24 hours or slightly more now. That's fast enough for 99.9% of people. And the 0.1% who might be willing to pay a huge premium for supersonic travel aren't numerous enough to justify the huge development cost of a new supersonic airliner even if the sonic boom issue could be overcome.

Perfectly stated.
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cloudboy
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RE: Possible Supersonic Routes - Economic Viability

Tue Oct 06, 2015 3:51 pm

Premature question. Until we know the specifications and performance of the aircraft in question, we can't accurately guess at the possible routes. The map that B2707SST made does a good job of showing some potential transpacific flights that have minimal impact on land. But we don't know how the aircraft will perform over land. will they find a way (different engines, perhaps?) that let it fly subsonic efficiently/ What kind of range will we have and at what kind of capacity? Would freight be possible? What kind of economics? Yeah we have lots of guesses on this, mostly based on outdated data and preheld beliefs about customers. Until we get concrete data though, it is pointless to decide if it will or won't work.
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DocLightning
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 3:28 am

Quoting Viscount724 (Reply 15):
You can be almost anywhere in the world within 24 hours or slightly more now. That's fast enough for 99.9% of people. And the 0.1% who might be willing to pay a huge premium for supersonic travel aren't numerous enough to justify the huge development cost of a new supersonic airliner even if the sonic boom issue could be overcome.

They said that about ocean liners back in their day. Nobody will ever need to go faster than 30 knots.
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Matt6461
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 2:55 pm

Aerodynamicist Walter Pfenninger predicted that a strut-braced wing could raise an SST's L/D to around 16, up from from the Concorde's ~9. Plus the SBW would be lighter due to the bending moment being taken by the strut's tension resistance instead of a horizontal spar's bending resistance.

If we combine the a ~75% increase in L/D, a ~10% lower OEW, and a ~20% decrease in SFC, the Breguet range equation - from a Concorde baseline - would give about 9,000+nm range.

Boeing and NASA have begun seriously researching SBW's, and their figures seem not to indicate as great a benefit as Pfenninger and some others predicted. But they're using a narrowbody baseline, where the SBW has lower benefit.

I don't know if Pfenninger was anywhere near the mark. It also isn't clear that recent engine advances would translate as well to the SST, as these typically involve spinning the fan slower relative to the core and that's not possible with an SST. But if Pfenninger was close we could see a future in which fuel becomes a much lower portion of operating cost and range is structurally cheap. In that environment an SST starts to make more sense.

There's also the possibility of low space vehicles exiting the stratosphere to provide even quicker trips than an SST without the sonic boom concerns.

Quoting cloudboy (Reply 17):
Until we get concrete data though, it is pointless to decide if it will or won't work.

Being on an internet forum filled with amateurs (and some pros) discussing ideas they think are cool seems pointless given your logic.

[Edited 2015-10-07 07:56:57]
 
B777LRF
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 9:25 pm

Even if only 0.1% of global airline passengers were willing to part with enough cash for a SST passage, that still amounts to several million passengers a year.

Neither A nor B are even remotely interested in gambling their existence on an SST adventure, regardless of the potential windfall, and that basically means the only avenue left is in the biz jet world. But that's an even harder financial proposition, as those wealthy enough to plunge 250 Mill on a jet prefer something quite a bit larger than a Citation - which was, in rough number, the cabin size proposed. That limited the market even further, making it quite clear to the various bidders, that the ROI was way into negative territory. In this day and age the corporate world is ruled by balance sheets and quarterly reports, and is deeply risk averse. Not an environment conducive to the introduction of something revolutionary. Aerion is still trying to plow ahead, and all possible power to their collective elbows. But I, sadly, just don't see it happen unless there's a ground-breaking, nee quantum, leap in technology.

Quoting Adipasquale (Reply 8):
Even Concorde did not sell nearly as many copies as originally projected as there is really not a huge market for supersonic flights.

Concorde failed to attract additional orders because a) it became available right at the time fuel prices sky rocketed, plunging the global airline industry into a deep financial abyss, b) no country would grant supersonic overflight permits and c) folks on the other side of the pond fighting political battles, keeping the aircraft off the very ocean it was designed to cross which lead to d) US airlines canceling their purchase intentions.

But BA and AF proved there was a market, and with less stringent rules and political meddling the aircraft could have been viable for a much larger number of airlines. Might never have sold more than 200 even in the very best of circumstances, but what a world to live in where Concorde's would be buzzing around the globe!
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Viscount724
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 10:44 pm

Quoting DocLightning (Reply 18):
Quoting Viscount724 (Reply 15):
You can be almost anywhere in the world within 24 hours or slightly more now. That's fast enough for 99.9% of people. And the 0.1% who might be willing to pay a huge premium for supersonic travel aren't numerous enough to justify the huge development cost of a new supersonic airliner even if the sonic boom issue could be overcome.


They said that about ocean liners back in their day. Nobody will ever need to go faster than 30 knots.

And the cost of making ocean liners faster, for example the S.S. United States, made operations uneconomic, much like trying to make airliners go faster. Ironically, most of today's airliners are slower than they were when the 707 went into service 57 years ago this month..
 
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 11:04 pm

Quoting Viscount724 (Reply 21):
ike trying to make airliners go faster. Ironically, most of today's airliners are slower than they were when the 707 went into service 57 years ago this month..

Right. I actually am skeptical that supersonic airliners will ever become viable because even if they are made of magical crystallized unicorn tears and burn angel farts for fuel, they will still require MORE magical crystallized unicorn tears and angel farts per ASM than their subsonic counterparts.

I suspect that airliners will be replaced by a different technology (hyperloop?).
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Starlionblue
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 11:06 pm

Quoting Matt6461 (Reply 19):
There's also the possibility of low space vehicles exiting the stratosphere to provide even quicker trips than an SST without the sonic boom concerns.

This may well be the way things go. Despite its recent difficulties, Virgin Galactic and Spaceship Two could be the beginning of development for such a transport system. Go suborbital very fast (2-3 hours from London to Los Angeles) and only make a boom over the ocean close to departure and destination. You could leave Heathrow, boost over the North Sea, then arrive with a bang over the Pacific or the Mojave Desert.

Solves the noise problem and also gives a much bigger speed advantage over current airliners. No longer 2-3 times as fast but 6-7 times as fast.

Certification of such a vehicle would generate quite a pile of paperwork, I imagine.  
Quoting Viscount724 (Reply 21):

Quoting DocLightning (Reply 18):
Quoting Viscount724 (Reply 15):
You can be almost anywhere in the world within 24 hours or slightly more now. That's fast enough for 99.9% of people. And the 0.1% who might be willing to pay a huge premium for supersonic travel aren't numerous enough to justify the huge development cost of a new supersonic airliner even if the sonic boom issue could be overcome.


They said that about ocean liners back in their day. Nobody will ever need to go faster than 30 knots.

And the cost of making ocean liners faster, for example the S.S. United States, made operations uneconomic, much like trying to make airliners go faster. Ironically, most of today's airliners are slower than they were when the 707 went into service 57 years ago this month..

One thing seems to be certain. It is hard to predict the future with any certainty. Bold statements like "no one will ever need more than 640k of memory" or "traveling at speed on a train will drive people insane" seem more likely to be proven wrong than right.
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B2707SST
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RE: Possible Supersonic Routes - Economic Viability

Wed Oct 07, 2015 11:13 pm

Quoting cloudboy (Reply 17):
Premature question. Until we know the specifications and performance of the aircraft in question, we can't accurately guess at the possible routes. The map that B2707SST made does a good job of showing some potential transpacific flights that have minimal impact on land. But we don't know how the aircraft will perform over land. will they find a way (different engines, perhaps?) that let it fly subsonic efficiently/ What kind of range will we have and at what kind of capacity? Would freight be possible? What kind of economics? Yeah we have lots of guesses on this, mostly based on outdated data and preheld beliefs about customers. Until we get concrete data though, it is pointless to decide if it will or won't work.

For those really interested in these details, a publicly available summary of the NASA High Speed Research Program is a great place to start. It dates from 1997, so it's not exactly current, but that was also the last time the topic has been seriously addressed. The consensus is that 5,000 nm of range and 250-300 pax is the "sweet spot" for a new SST. Bigger and longer-range aircraft get heavy very quickly, increasing fuel burn and reducing ability to meet noise standards. Smaller, shorter-range aircraft are not capable enough to be economically viable.

Quoting Matt6461 (Reply 19):
Aerodynamicist Walter Pfenninger predicted that a strut-braced wing could raise an SST's L/D to around 16, up from from the Concorde's ~9. Plus the SBW would be lighter due to the bending moment being taken by the strut's tension resistance instead of a horizontal spar's bending resistance.

This is a vastly higher L/D than I've seen for any SST design, which makes me skeptical. Concorde was only 7.3, and traditional delta wings max out around 11:


Quoting Matt6461 (Reply 19):
It also isn't clear that recent engine advances would translate as well to the SST, as these typically involve spinning the fan slower relative to the core and that's not possible with an SST

Forum member GDB, who was with BA's Concorde maintenance division, has said that Rolls-Royce thinks a new SST engine would not have much of an SFC advantage over the Olympus 593 at supersonic cruise. Pure turbojets like the Olympus are the ideal powerplants for supersonic cruise but could never meet modern noise requirements, and the higher bypass ratios and mixer/ejector nozzles needed to do so will reduce propulsive efficiency at cruise. RR thought this would largely offset gains from higher pressure ratios and other advances since the 1960s. New engines are also likely to be much heavier than the Olympus.

Quoting Matt6461 (Reply 19):
There's also the possibility of low space vehicles exiting the stratosphere to provide even quicker trips than an SST without the sonic boom concerns.

That would avoid the boom issue, but building a reusable hypersonic spaceplane is an order of magnitude or two more difficult than an SST. You need to have rocket engines, oxygen tankage, hypersonic aerodynamics, reentry heat management, closed-loop pressurization, and a whole host of other systems that make supersonic cruise look tame by comparison.

Quoting B777LRF (Reply 20):
a) it became available right at the time fuel prices sky rocketed, plunging the global airline industry into a deep financial abyss

Certainly the oil crisis did not help Concorde's prospects, but every Concorde customer except BA and AF (including launch customer Pan Am) had let their options expire in January 1973. The Yom Kippur War and OPEC embargo sent oil prices soaring in October 1973. Thus, Concorde had failed to sell even in a cheap-oil environment; the oil crisis was just a further nail in the coffin.
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cloudboy
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RE: Possible Supersonic Routes - Economic Viability

Thu Oct 08, 2015 2:30 pm

Quoting Matt6461 (Reply 19):
Being on an internet forum filled with amateurs (and some pros) discussing ideas they think are cool seems pointless given your logic.

Been there, done that, have the scars. I argued that same point many a time, needless to say it was a battle and war I lost.

I am not saying that the idea is a bad one, or that there is no room to discuss ideas. I am saying that the argument seems to still be misdirected into details about statistics, figures, and studies that are based on only one set of conditions. WE don't know enough yet about the possibilities and conditions to argue over those. That is where the danger is - FT is so quick to not only kill an idea, but vilify anyone or any group that dares bring up the idea, that even simple discussions have negative ramifications.

No one has even thought about the need for high speed freight/delivery, the need to get technicians and experts from one continent to the other rapidly, and medical/family emergencies. We don't know that such an aircraft can or can't fly over land, as we don't know yet whether it will only have supersonic engines, or could it also have regular engines which allow it to cross land subsonic for an hour or so. The fact is we have supersonic fighters and bombers already, the technology that we had back in the 60's and 70's has progresses. Heck, the 747 was started at the same time - and look how much progress has been made there.

I have no problem discussing the potentials and the possibilities of how to make it work - so long as it is constructive. I don't like how people attack anyone who comes up with a suggestions because they feel so strongly that they don't want supersonic aircraft they will stop at nothing to see it never happens.
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RE: Possible Supersonic Routes - Economic Viability

Thu Oct 08, 2015 10:41 pm

Quoting Starlionblue (Reply 23):
This may well be the way things go. Despite its recent difficulties, Virgin Galactic and Spaceship Two could be the beginning of development for such a transport system. Go suborbital very fast (2-3 hours from London to Los Angeles) and only make a boom over the ocean close to departure and destination. You could leave Heathrow, boost over the North Sea, then arrive with a bang over the Pacific or the Mojave Desert.

Solves the noise problem and also gives a much bigger speed advantage over current airliners. No longer 2-3 times as fast but 6-7 times as fast.

Unfortunately the Virgin Galactic thing is a dead end for any such long-range sub-orbital flight. The actual required velocities for such a think are more in the 7ks/s range (Mach ~20), a far cry from SS2's Mach ~3. To get that you're going to need much higher ISP engines than what SS2 is using, as well as a drastically higher fuel fraction (let's say you had a very small 10t MZFW aircraft, then you'd be looking at something like 70t of LOX/LH2). And then you need a carrier aircraft capable of launching that 80t vehicle. Then you see the same speed at reentry, so you need a real reentry system, only a bit less capable than what you need for a full orbital reentry.

IOW, basically nothing that SS2 is doing is applicable to the desired sub-orbital vehicle. Nice PR stunt, though.
 
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Starlionblue
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RE: Possible Supersonic Routes - Economic Viability

Thu Oct 08, 2015 10:52 pm

Quoting rwessel (Reply 26):
Unfortunately the Virgin Galactic thing is a dead end for any such long-range sub-orbital flight. The actual required velocities for such a think are more in the 7ks/s range (Mach ~20), a far cry from SS2's Mach ~3. To get that you're going to need much higher ISP engines than what SS2 is using, as well as a drastically higher fuel fraction (let's say you had a very small 10t MZFW aircraft, then you'd be looking at something like 70t of LOX/LH2). And then you need a carrier aircraft capable of launching that 80t vehicle. Then you see the same speed at reentry, so you need a real reentry system, only a bit less capable than what you need for a full orbital reentry.

IOW, basically nothing that SS2 is doing is applicable to the desired sub-orbital vehicle. Nice PR stunt, though.

I see what you are saying. However you have to start somewhere. Biplanes with radial engines aren't really applicable to swept wing jets but they were probably a necessary first step. If nothing else, SS2 drives regulation and teaches how suborbital flights might be conducted. The regulatory framework and public awareness are not important either.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
prebennorholm
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RE: Possible Supersonic Routes - Economic Viability

Sat Oct 10, 2015 2:16 am

Quoting rwessel (Reply 26):
Unfortunately the Virgin Galactic thing is a dead end for any such long-range sub-orbital flight. The actual required velocities for such a think are more in the 7ks/s range (Mach ~20), a far cry from SS2's Mach ~3. To get that you're going to need much higher ISP engines than what SS2 is using, as well as a drastically higher fuel fraction (let's say you had a very small 10t MZFW aircraft, then you'd be looking at something like 70t of LOX/LH2). And then you need a carrier aircraft capable of launching that 80t vehicle. Then you see the same speed at reentry, so you need a real reentry system, only a bit less capable than what you need for a full orbital reentry.

100% correct.

Funny thing is that we have been there, done that. Both "slow" short range (regional) hypersonic transport, and fast, ultra long range.

The "regional" one was the X-15 - B-52 combination, the long range one was the Space Shuttle with its fuel tank and solid boosters.

An intercontinental range hypersonic sub-orbital transport plane will be a slightly downgraded Space Shuttle, no more, no less. It may be bigger or smaller, you scale it to the wanted capacity. It may have a different configuration, just like several alternative configurations were evaluated before the design was frozen. There are no new inventions which significantly favors a configuration which dramatically varies from those considered back in the early 70'es when the Shuttle was designed.

Quoting rwessel (Reply 26):
...basically nothing that SS2 is doing is applicable to the desired sub-orbital vehicle.

Exactly! SS2 is about lifting a few pax to altitude to see the curvature of the earth, and experience a couple of minutes of zero G. Then fall vertically down in parachute mode, and change to sailplane mode before landing where it took off.

Comparing a SS2 to a sub-orbital transport is like comparing a dog sledge to a Porsche SUV.

The only really new thing on SS2 is a much less efficient, and VERY much less expensive rocket engine. It won't help a hypersonic transport in any way.
Always keep your number of landings equal to your number of take-offs
 
rwessel
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RE: Possible Supersonic Routes - Economic Viability

Sat Oct 10, 2015 7:53 pm

Quoting cloudboy (Reply 25):
No one has even thought about the need for high speed freight/delivery, the need to get technicians and experts from one continent to the other rapidly, and medical/family emergencies.

I can get a technician or doctor teleconferenced to a remote site in seconds. Surely we can find someone local to turn some screws on command or wield a scalpel? As to parts or medical emergencies, supersonic flight would help in those cases where you could deal with several hours delay (the minimum local response time anyway), but not ~20 hours (maximum effort subsonic flight half way around the planet). And even the ~20 hour response is almost always going to be on the high side - a few regional support bases will reduce that drastically. Obviously there are cases where those requirements would apply, but it seems pretty limited.

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