The potential of SST?

Lets see if we can't reduce some of the speculation about sonic booms damage. The info below is from the Wiki article, my comments/questions are in red.

A vehicle flying at greater altitude will generate lower pressures on the ground, because the shock wave reduces in intensity as it spreads out away from the vehicle, but the sonic booms are less affected by vehicle speed. US SSTs were projected to fly at 70,000', but even if this wasn't reached 50-60,000' is still pretty high.

Aircraft Speed Altitude Pressure (lbf/ft2) Pressure (Pa)

SR-71 Blackbird Mach 3+ 80,000 feet (24,000 m) 0.9 43
Concorde (SST) Mach 2 52,000 feet (16,000 m) 1.94 93
F-104 Starfighter Mach 1.93 48,000 feet (15,000 m) 0.8 38
Space Shuttle Mach 1.5 60,000 feet (18,000 m) 1.25 60

Buildings in good condition should suffer no damage by pressures of 530 Pa (11 psf) or less. And, typically, community exposure to sonic boom is below 100 Pa (2 psf). Ground motion resulting from sonic boom is rare and is well below structural damage thresholds accepted by the U.S. Bureau of Mines and other agencies. The US SST sonic boom was expected to be some 1/3 worse than the Concorde, so maybe 3 lbf/ft2 or about 1/4 of the level that will cause no damage to well maintained buildings.

Ground width of the boom exposure area is approximately 1 statute mile (1.6 km) for each 1,000 feet (300 m) of altitude (the width is about five times the altitude); that is, an aircraft flying supersonic at 30,000 feet (9,100 m) will create a lateral boom spread of about 30 miles (48 km). SST would create a sonic boom carpet ~50-60 miles wide, the US is over 2000 miles wide from north to south so 3 or 4 east-west flight paths will cover a miniscule amount of land in CONUS.

For a boom to reach the ground, the aircraft speed relative to the ground must be greater than the speed of sound at the ground. For example, the speed of sound at 30,000 feet (9,100 m) is about 670 miles per hour (1,080 km/h), but an aircraft must travel at least 750 miles per hour (1,210 km/h) (Mach 1.12, where Mach 1 equals the speed of sound) for a boom to be heard on the ground. So an SST can travel at transonic speed without the sonic boom reaching the ground, so could fly transonic over the eastern half of CONUS.

As an aside, horses get spooked by EVERYTHING and get used to things if exposed to them. If we were going to limit human activity to what doesn't initially spook horses then we wouldn't have trains or cars, horses and other animals would get used to semi-regular sonic booms.

Bear in mind that the political issues raised by mitigated sonic booms have to be weighed against the employment generated by SST production and the other powerful interests that would use SSTs from the power centres on the US coasts. If the SST programme progresses better then I think the political environment will change to make it work.
 

Errolwi

Monthly Donor
Not once. BA's fleet were, however, regularly utilised on charters for 'ordinary people' to enjoy a couple of hours over the Med & experience supersonic flight. They were ludicrously popular, incredibly profitable & created more goodwill for the airline (and particularly, the aircraft itself) than seems plausible today.

Plus things like going to New Zealand to chase an eclipse.
 
So an SST can travel at transonic speed without the sonic boom reaching the ground, so could fly transonic over the eastern half of CONUS.
In theory, sure. In practice, there's no point since it would be more expensive than traveling subsonically due to the drag spike around transonic velocities, while offering little in the way of time benefits. Mach 1 is not that much faster than Mach 0.85; for example, going from Mach 0.85 to Mach 1 shaves off just half an hour from the flight time for an aircraft going directly from New York City to Los Angeles. If the aircraft was instead only flying subsonic to the Mississippi, then supersonic thereafter, then the benefits would be even less.

What is the best case scenario for SSTs if things fell their way?
The best case scenario is that a few hundred go into service around the world and operate more or less profitably for a few decades. By the 1990s or 2000s they're wearing out, and airlines replace them with cheaper, more economical 777s and A330s instead of ordering any kind of replacement despite attempts by Boeing and Airbus to flog some kind of SST-2 (Boeing IOTL did something similar with its "Sonic Cruiser" despite SSTs never coming into vogue, and got absolutely nowhere). After all, modern widebody twinjets are inherently cheaper to operate than supersonic aircraft due to the higher drag experienced at supersonic speeds and the lower efficiency of engines at those speeds, and passengers are empirically more likely to choose a cheaper than a faster or more comfortable seat, so the twinjets actually have similar revenues despite not being able to charge a supersonic premium. The SSTs so displaced usually end up in charter service, and ultimately while they still exist today they represent a dead end much like the trijets of the same period.
 
Plus things like going to New Zealand to chase an eclipse.

I suspect you might mean 001's flight over the Sahara in 1973 - a test flight / scientific endeavour, as it predates commercial service by three years & was flown by the first prototype, which required structural modification in the form of fuselage top 'portholes' for the instruments used. The only PAX were professional astronomers, who were able to study totality for around seventy minutes - a feat unrepeated, either before or since.
 
theory, sure. In practice, there's no point since it would be more expensive than traveling subsonically due to the drag spike around transonic velocities, while offering little in the way of time benefits. Mach 1 is not that much faster than Mach 0.85; for example, going from Mach 0.85 to Mach 1 shaves off just half an hour from the flight time for an aircraft going directly from New York City to Los Angeles. If the aircraft was instead only flying subsonic to the Mississippi, then supersonic thereafter, then the benefits would be even less.

I know it's not ideal but bring it up as it might be used as a mitigation tactic over particularly sensitive areas. I'm thinking a mix of speeds, heights and routing could get SST accepted by the US for over CONUS routes.
 
The best case scenario is that a few hundred go into service around the world and operate more or less profitably for a few decades.

I'd agree with this more or less.

the 1990s or 2000s they're wearing out, and airlines replace them with cheaper, more economical 777s and A330s instead of ordering any kind of replacement despite attempts by Boeing and Airbus to flog some kind of SST-2 (Boeing IOTL did something similar with its "Sonic Cruiser" despite SSTs never coming into vogue, and got absolutely nowhere). After all, modern widebody twinjets are inherently cheaper to operate than supersonic aircraft due to the higher drag experienced at supersonic speeds and the lower efficiency of engines at those speeds, and passengers are empirically more likely to choose a cheaper than a faster or more comfortable seat, so the twinjets actually have similar revenues despite not being able to charge a supersonic premium. The SSTs so displaced usually end up in charter service, and ultimately while they still exist today they represent a dead end much like the trijets of the same period.

I disagree that the impact that a few hundred SSTs will be minimal because airlines make something like 80% of their money from 20% of their passengers. A qantas Ap380 has 14 First, 64 Business, 35 Premium Economy and 371 Economy seats. For a round trip to London the economy generates about $550,000, premium $112,000, business $480,000 and first class $225,000 in ticket sales.

SSTs will cater to the ~110 people willing to pay $3200-$16,000 rather than the ~370 tightarse pricks (like me :happyblush) willing to only pay $1500.

In La world where ssts are not a rare novelty I think expectations would be generated to build a follow-up sst once the first generation leaves service.
 
I don’t think even with 100+ jets that the sonic boom issue can be made to go away.
Imagine if you house happens to sit under that line. Of you horses.

And I also don’t understand why facing seats backwards would give you any more room then facing them forward. And the windows are not effecting space but may effect structure especially in a supersonic aircraft with the heat issues.

I am not sure about space but rear facing seats are statistically safer. Unfortunately most people get nervous when they think that they are going backwards.

Removing windows means that you don't have to put the seats in a nice line. Eg. you can stick them where a luggage compartment is now and the passengers wouldn't notice the difference.
 

Errolwi

Monthly Donor
I suspect you might mean 001's flight over the Sahara in 1973 - a test flight / scientific endeavour, as it predates commercial service by three years & was flown by the first prototype, which required structural modification in the form of fuselage top 'portholes' for the instruments used. The only PAX were professional astronomers, who were able to study totality for around seventy minutes - a feat unrepeated, either before or since.

I was conflating the 1986 visit to NZ including viewing Halley's Comet (my car was stolen the day it was at Auckland, I remember because by grandfather and brother were at AKL so bro wasn't available to come pick me up from where I was stranded) with the 1999 eclipse trips (I was in London at the time).
 
aroute.jpg


broute.jpg
Thx for these.

First blush, a question: couldn't they make transpolar flights Anchorage to London or Paris? (Or, in the same vein, Prince Albert, Edmonton,
Prince George, or Winnipeg to London/Paris/Moscow? Or even Prince Rupert to Tokyo or Beijing?
 
I disagree that the impact that a few hundred SSTs will be minimal because airlines make something like 80% of their money from 20% of their passengers. A qantas Ap380 has 14 First, 64 Business, 35 Premium Economy and 371 Economy seats. For a round trip to London the economy generates about $550,000, premium $112,000, business $480,000 and first class $225,000 in ticket sales.

SSTs will cater to the ~110 people willing to pay $3200-$16,000 rather than the ~370 tightarse pricks (like me :happyblush) willing to only pay $1500.
Your own numbers show that the economy seats account for nearly 40% of the revenue of this flight, while at the same time the A380 is probably cheaper to operate than the 110 seat SST because of the fuel efficiency hit jet engines take from going faster, the higher drag of supersonic compared to subsonic flight, the greater wear and tear on the aircraft at supersonic speeds, and so on and so forth. So from the airline perspective they're getting 60% of the revenue while paying some proportion--110%, 120%, maybe more--in operations, maintenance, and fuel costs due to the performance impacts of going supersonic. How does this make any financial sense whatsoever? The answer is that it doesn't, which is why airlines have not been warm to the idea of new SSTs, the Sonic Cruiser, or, for that matter, even the Convair 880 and 990 back in the day.
 
A SST be mostly first class passengers second and third class passengers when take aircraft similar to the 747 for economic reasons. The 747 was originally designed to fill the roles an SST couldn't perform. namely being a cost of station freighter, someone would come to the same conclusion Juan Tripp didn't realize how efficient the 747 would be for carrying passengers.
 
Your own numbers show that the economy seats account for nearly 40% of the revenue of this flight, while at the same time the A380 is probably cheaper to operate than the 110 seat SST because of the fuel efficiency hit jet engines take from going faster, the higher drag of supersonic compared to subsonic flight, the greater wear and tear on the aircraft at supersonic speeds, and so on and so forth. So from the airline perspective they're getting 60% of the revenue while paying some proportion--110%, 120%, maybe more--in operations, maintenance, and fuel costs due to the performance impacts of going supersonic. How does this make any financial sense whatsoever? The answer is that it doesn't, which is why airlines have not been warm to the idea of new SSTs, the Sonic Cruiser, or, for that matter, even the Convair 880 and 990 back in the day.

I wouldn't be calling 40% of the revenue from 80% of the passengers a great success , these low margins is why air travel is so shit these days.

I don't doubt that its difficult to sell a concept, but if the government is paying for the development of the concept then its a much easier sell. I still think that if about 200 ssts were in service they would be looked at differently than we do today.

Sorry if i sound grumpy, I'm in Singapore sweating like a sex criminal after an 8 flight and waiting for the 14 hour flight to London. No wonder I gave such a hard on for ssts.
 
I wouldn't be calling 40% of the revenue from 80% of the passengers a great success , these low margins is why air travel is so shit these days.
Indeed, but remember that the airlines used to have more high-margin seats and charged more even for economy passengers. They didn't change because they hate their customers; they changed because they made more money that way. For that matter, if they didn't like economy seats so much they could switch to all-first/business widebody twinjets (which would be cheaper to buy and operate than A380s); but they don't. Empirically, airlines do better trying to sell more seats even at a lower price than trying to sell a premium product.

I don't doubt that its difficult to sell a concept, but if the government is paying for the development of the concept then its a much easier sell. I still think that if about 200 ssts were in service they would be looked at differently than we do today.
In the 1990s and 2000s? No, the government isn't going to just pay for the development. They might fund some R&D on their own, and they might provide loans or subsidies to the company to get the program started, but with the neoliberal consensus firmly in place the aircraft manufacturers will be firmly in the driver's seat. At best I can see a company (Airbus) making a massive but wrong-headed bet about where the market is going, but I can't see why they would make that bet when it would be pretty obvious from market experience that it would be unlikely to pan out (then again, they ignored warning signs that the A380 wasn't a very good idea, so maybe there's just something in the water in Toulouse...)
 

DougM

Donor
Ok so according to the numbers above i was off by a factor of 5 so we are looking at 200,000 individual owners getting screwed over at a minimum. If you cut the land size in half that goes up to 400,000 and if you need a corridor for both directions because you don’t want to or can’t stack in alternating directions by elevation then you could be up to 800,000 individual land owners.
And don’t forget we need wiggle room on these routes so you could easily triple that number when accounting for that.
Now add in routing to avoid storms and you really have problems as that can take you a hundred miles out of your way. So we really are looking at a path 10miles wide that is majority effected. 50 miles wide that is effected most days by noise, a 150 miles wide that is effected on some days as the route is slightly modified and a route that is as much as 300 miles wide that could occasionally bee effected by rerouting to avoid storms. Multiple this by 3 routes min or probably 3 each way and we are looking at as much as 300 miles be effected daily and 900 miles being effected occasionally and pretty much the entire country could get the occasional rerouting to avoid storms.

That is hardly insignificant. And you will see property in those corridors, values drop like a rock. And you could easily see the land owners taking the airlines to court for financial damage assuming the government was dumb enough to let the fly them.
Which in 1975 they were not going to. As back then the government was not willing to blatantly screwed over that much of the country to help a few large corporations sell high priced tickets to millionaires.
Today? I would not put it past them.
 
Indeed, but remember that the airlines used to have more high-margin seats and charged more even for economy passengers. They didn't change because they hate their customers; they changed because they made more money that way. For that matter, if they didn't like economy seats so much they could switch to all-first/business widebody twinjets (which would be cheaper to buy and operate than A380s); but they don't. Empirically, airlines do better trying to sell more seats even at a lower price than trying to sell a premium product.

That's only true to a point, and the A380 again provides a good example. The plane itself is able to cram in up to 850 passengers but the most any airline has is a part of the Emirates fleet with 615 in 2 classes and even they have most of their fleet in the 490 passenger range. While the small Concorde will struggle the ~230 seat US SST will have far more options to mix and match seating arrangements to maximise revenue. Also I think that the speed of SSTs, assuming that they are common enough, could open up markets that we can't imagine because of the OTL niche nature of the Concorde. How much of the driver toward Business and Premium Economy is the brute fact that flights take so long and how much of a limitation on travel is the time-suck nature of subsonic long haul flights? If you only have 2 weeks to travel spending 5 of those days on long haul flights acts as a deterrent, certainly I feel that if I'm going to spend 8-16 hours on a flight I want to spend more than a few days at the destination.

In the 1990s and 2000s? No, the government isn't going to just pay for the development. They might fund some R&D on their own, and they might provide loans or subsidies to the company to get the program started, but with the neoliberal consensus firmly in place the aircraft manufacturers will be firmly in the driver's seat. At best I can see a company (Airbus) making a massive but wrong-headed bet about where the market is going, but I can't see why they would make that bet when it would be pretty obvious from market experience that it would be unlikely to pan out (then again, they ignored warning signs that the A380 wasn't a very good idea, so maybe there's just something in the water in Toulouse...)

Hell no, the 'Concorde moment' is in the 60s and will not be repeated. However ITOL research into mitigating the sonic boom continued for decades after the SST concept died.

With the lessons of 20 years operating ~200 SSTs the job of developing any follow-on would be much easier. It would be optimised better than the prestige project SSTs of the 60s, maybe it will travel slower but will be much quieter and cheaper to run etc.
 
Ok so according to the numbers above i was off by a factor of 5 so we are looking at 200,000 individual owners getting screwed over at a minimum. If you cut the land size in half that goes up to 400,000 and if you need a corridor for both directions because you don’t want to or can’t stack in alternating directions by elevation then you could be up to 800,000 individual land owners.
And don’t forget we need wiggle room on these routes so you could easily triple that number when accounting for that.
Now add in routing to avoid storms and you really have problems as that can take you a hundred miles out of your way. So we really are looking at a path 10miles wide that is majority effected. 50 miles wide that is effected most days by noise, a 150 miles wide that is effected on some days as the route is slightly modified and a route that is as much as 300 miles wide that could occasionally bee effected by rerouting to avoid storms. Multiple this by 3 routes min or probably 3 each way and we are looking at as much as 300 miles be effected daily and 900 miles being effected occasionally and pretty much the entire country could get the occasional rerouting to avoid storms.

That is hardly insignificant. And you will see property in those corridors, values drop like a rock. And you could easily see the land owners taking the airlines to court for financial damage assuming the government was dumb enough to let the fly them.
Which in 1975 they were not going to. As back then the government was not willing to blatantly screwed over that much of the country to help a few large corporations sell high priced tickets to millionaires.
Today? I would not put it past them.

The table I posted earlier shows the actual impact of the sonic boom well within the limits of what the USG deems acceptable for the impact of other things like mines and industries.

In the end the argument would be between those who support it like user and industry groups and their Representatives and those who oppose it such as the representatives of Congressional districts that you say will have to endure a sonic boom that is withing limits set down for other industries. The mitigations I suggest are ways of buying votes, or at least reducing the vehemence of opposition; with careful route selection the sonic-boom based opposition might be only 100-150 of the Congress/Senate members and a route, altitude, speed change might be enough to sway single legislators away from sonic-boom based opposition to gt things done.
 

DougM

Donor
Actually you will see a LOT more opposition.
The anti wealthy crowd will hate it on principle as it is by definition only the well to do that will be able to afford the upcharge in ticket price.
And don’t forget that this is going to get huge support from the “fly over states”. As these aircraft are mostly going to go coast to coast as a Flight from Kansas to anyplace (for example) is not worth the cost to save a relatively little amount of time.
The environmental crowed will hate it on as it will not be as efficient and will pollute more.
If we are talking Concorde 2 then the anti Europe crowd (a bigger factor in the 70s-80s) will oppose it.
And don’t forget the opposition from the reps and senators from the states with opposing aircraft manufacturers in them. McDonald Douglas and it’s home state is not going to support this if Boeing gets the build for example.
Add in all the representatives from the effected areas. INCLUDING where the airports themselves are as odds are these things are noicer then a traditional plane on takeoff as the engines will be different. .
And don’t forget the Senators from the states that are getting the corridors over them. And that will be a lot of states about 24 to 28 by the time you do a norther corridor and a southern as well as the north south. And if you get 17 states worth (or 34j then this bill is dead in the water.

So yes this IS going to make living under them annoying. I live in the Suburbs about 15-25 miles from our local airports and NOT on the typical path for takeoff or landing for either of them. But every once in a while (about every other month or so) for some reason for about an hour or two I get a good number of aircraft over my head. I also live in a well built modern house with good insulation and windows and still those aircraft get annoying. And that is with relatively quite modern aircraft designed to meet modern noice rules,

And finally you have the knock on problem that the subsonic manufactures (Engine and Airframe) as well as any airline not flying supersonic are going to have problems with the sound rules be enforced on them(and made harsher as time goes on) but those super sonic guys are using noisy engines and making “sonic bombs all over the country”. So you have HUGE issues with noice abatement rules.

And this is not just a US issue. You will have similar arguments in any country that would be crossed by these things at speed.

That being said enough aircraft go trans oceanic that the aircraft could be a success without ever crossing the US. It would not be as easy but it can be done. And changing aircraft was much more common back in the day when spoke and hub was the order of the day and it was a lot easier when security was almost non existent.
So the idea that the aircraft has to fly across the US to be a success is a bit of a red herring.
 
Top