If fuel cost and fuel efficiency were not the issue, what is the maximum speed (air speed and ground speed) that business jets or airliners could travel at without exceeding the maximum noise and sonic boom allowed or as regulated in the USA, Europe and the rest of the world. I need to know why there are no faster business jets and for business class airliners given that private and business fliers are prepared to pay a premium
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DeltaLima
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securitydude5
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1...mach 1? There is no fixed ground speed, since that depends on the wind. – 60levelchange Sep 17 '17 at 06:28
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1related, if not duplicate: https://aviation.stackexchange.com/q/11936/1467 & https://aviation.stackexchange.com/q/3748/1467 " I need to know why there are no faster business jets" you can't avoid efficiency if you want to know that. – Federico Sep 17 '17 at 06:40
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3"[...] given that private and business fliers are prepared to pay a premium" Where did you come to that conclusion? I'm sure that it is quite the opposite, nobody is going to pay a premium to shave 5-10 minutes off a short trip, and maybe 30 minutes off of an international trip. ATC can eat up or make those kinds of savings... – Ron Beyer Sep 17 '17 at 12:04
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1@RonBeyer for "given" read "supposing". – hobbs Sep 29 '17 at 19:40
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2I first thought the proper answer should be: Glacial speed. It will take ages for a government bureaucracy to come up with new regulations. – Peter Kämpf Sep 29 '17 at 23:21
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Business jets are developed to different rules than airliners. The biggest difference is that, indeed, fuel price and fuel efficiency are not an issue when what counts are bragging rights for the fastest plane on the ramp. Their speed has steadily increased and is now at Mach 0.935 for the fastest models. Compare that to Mach 0.78 to 0.85 for regular airliners.
Supersonic business jets were proposed several times in the last decades, but so far nobody has risked to spend the money it needs to bring one design to a type certificate.
Since supersonic flight over land is heavily restricted, the fastest speed would be Mach 0.99. However, since the speed of sound decreases with increasing altitude in parallel with air temperature, what is Mach 1.15 in 40.000 ft becomes only Mach 0.998 on the ground, so the shock will disappear close to the ground. If the goal is to avoid the shock on the ground, flight speed high up can very well be mildly supersonic. However, this will place the airplane close to its drag maximum, giving it exquisitely poor efficiency for a small gain in speed.
Peter Kämpf
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@Abdullah Yes, the sharp, N-shaped pressure profile will dissipate and be stretched out once the speed of sound is higher than the speed of the wavefront. – Peter Kämpf Feb 25 '21 at 13:53
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I thought it would just be refracted and would accelerate – Abdullah is not an Amalekite Feb 25 '21 at 14:01
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@Abdullah But not down, only up. As long as the speed of sound is faster than the source of the noise, what reaches the ground is persistent subsonic noise, no sonic boom. But it needs some distance to dissipate enough. The example with Mach 0.998 on the ground will still be rather loud and concentrated. – Peter Kämpf Feb 25 '21 at 16:39
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So it has to do with the difference between shockwave and sound wave? – Abdullah is not an Amalekite Feb 25 '21 at 16:48
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@Abdullah The shockwave is a soundwave. Soundwaves are tiny pressure variations, and so are shockwaves. – Peter Kämpf Feb 25 '21 at 18:43
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True Air Speed limit is Mach 1. Ground speed is not relevant to this question.
The reason there are currently no flying supersonic business aircraft is that designing and building an aircraft capable of supersonic flight is very expensive and technically challenging.
Juan Jimenez
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3Mach 1 is a Mach limit. Since speed of sound depends on temperature, the true air speed limit varies with altitude. – Jan Hudec Sep 30 '17 at 21:37
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1Mach 1 is expressed in knots in aviation and that number is adjusted for altitude. Mach numbers are constants. So to avoid noise restrictions you have to fly at or below Mach 1, which can be any range of speeds depending on your altitude. So, your True Air Speed has to be below that of Mach 1 at the altitude you are flying. That's why I refer to it as the limit, because just saying you have to fly below Mach 1 doesn't really mean anything in and of itself. – Juan Jimenez Oct 01 '17 at 10:23
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It is 0.99 Mach over land. I don't see any restrictions over the ocean. Based on the top answer to this aviation SE question, I think if you can design a more stealthy hypersonic transport aircraft and fly it at high enough altitudes in the stratosphere, you may minimize the sonic boom to the extent that it is a non-issue. The NASA graph in the answer shows that the XR-71 has an insignificant sonic boom when cruising at 60,000 ft MSL compared to the Concord SST.
Ram-jet technology would eliminate the need for the turbine compressor used on current jet engines thus allowing the aircraft to be quieter and more streamlined and stealthier.
0tyranny0poverty
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