Starlionblue wrote:I'll just leave this here...
XAM2175 wrote:Um, the "holy grail" of super-cruise has already been achieved, by Concorde. Afterburning ("re-heat") was only used for take-off and the trans-sonic part of the flight, between Mach 0.95 and 1.70. At all other times it flew on normal thrust alone.
rjsampson wrote:Yet, many years ago, there was an airliner (the 727) that routinely cruised at Mach .83. A few folks on here reached .89 on the 72. That is fast, for an early jetliner. A230s and 73x's do not compare to the 72... even though they were the same size.
gloom wrote:Yeah, adding to above.
The holy grail is to go above (or behind, rather) that sound barrier, and achieve speed that can be sustained without using afterburner (since afterburner gives +50% thrust, but also +200% fuel consumption). The military have made it possible, generation 5 fighters usually are so called supercruise. F22 goes Ma 1.5-1.6 on supercruise.
It will take some time on commercial airliners to reach that level, though. My estimation would be 2050+, unless a new breakthrough technology becomes available. There are projects since 90s, or maybe even 80s, and none even started.
SCAT15F wrote:I'd be curious to see what the sonic cruiser could do today in terms of fuel efficiency with the strides made in engines since 2000.
.98 mach cruise plus faster climb and descent would definitely make up some time on 14+ hour sectors
The G650 and Citation X are really not any faster than the 747. Their long range cruise is still just mach .85. Sure they can top out at Mach .92 or slightly more. Well, the 747 can do that too and with a hell of a lot more passengers and cabin space. They all still use too much gas at that speed to make it useful for anything but short sectors. The Sonic Cruiser on the other hand is/was an entirely different class of airplane
wingscrubber wrote:If the question is why airliners don't cruise at higher Mach - it's just drag and fuel. Also, with the advent of long range ETOPs, the designers have to optimise the payload-range diagram for a lower MTOW, pushing them to slower speeds to get the same range you might have achieved by carrying a lot more fuel and two extra engines to lift it.
But, if the question is, why don't aircraft fly supersonic (anymore), it's actually more due to technical risk and military dual-use technology conflict than anything else.
Many often bleat on about the economic failure of 'the' Concorde - after all it only operated for 26 years and carried 300,000 passengers and led to the formation of the world's largest airliner manufacturing company, so 'failure' is quite charitable, no?
I frequently notice that the type who point this out often preceding Concorde with 'the' almost always leading into some jealous Aboulafia-like sneer about the fuel economy etc, but there was a more deep rooted resistance to what it represented than that, directly related to the political climate of the era in which it was developed, market protectionism and military technology parallels, but the fuel economy argument is the gripe that everyone remembers, boom paranoia and the Oklahoma City sonic boom tests notwithstanding. The fuel problems and public perception of the 'boom' is not insurmountable though.
Putting aside the political and technological reservations, which are merely psychological barriers and not impossibilities - there's no reason why we shouldn't build airliners which go supersonic, it's been done and it will be done again.
One thing that will drive us to it, is instead of the apparent fuel cost, the actual per-hour operating cost of aircraft could be the benefit; the power-by-the-hour lease model which underpins business jets considers other overheads such as the crew time and passenger through-put on any given route, fuel is just one of multiple factors that affect profitability. Ultimately airlines are just human logistics companies and if one can deliver the package more quickly and charge a premium for it while incurring less operating time, well that's a competitive edge.
But it's only a competition if there's more than one, Tu-144 was never a true contender and the US failed to field its own SSTs, allowing Concorde to be a white elephant on a plinth, in an ivory tower on top of a mountain - opening it up wide for criticism of its bourgeois opulence, because nothing else has ever come close to it.
Another driver for change will be the continued emergence of the BRIC nations into civil airliner manufacturing - eventually Airbus and Boeing will be knocked off their perch by cheaper Chinese, Brazilian and Russian equivalents in the next 4 decades, once they reach parity the western supersonic aspirations will return because it won't be possible to compete with BRIC manufacturers on price, you would have to compete with them on luxury.
'Boom' is the one to watch I feel, they seem to have grasped the fundamentals and have a big financial backer. Aerion on the other hand, especially judging by their initial engine selections and targeted cruise speeds, are kind of stumbling as far as I can see.
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