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Re:Will we ever fly supersonically over land? by avereveard on Saturday July 03, 2021 @04:26PM (#27724614)
not really the same, fighters are quite smaller than airliners.
Re:Will we ever fly supersonically over land? by Retric on Saturday July 03, 2021 @07:05PM (#27725730)
Less than you might think. Wingspan Concord 25.6m vs F-22 13.56m. Maximum takeoff weight Concord 185,000kg vs F-22 60,000kg.

Expanding that to all supersonic military aircraft and the Rockwell B-1 Lancer has a higher maximum takeoff weight than the concord. It’s a loud and heavy beast.

Re:Will we ever fly supersonically over land? by perl4ever on Saturday July 03, 2021 @07:37PM (#27725928)
I wonder if the comparison would be more frontal area than weight?
Re:Will we ever fly supersonically over land? by hollerith on Saturday July 03, 2021 @07:00PM (#27725696)
They might be smaller, but the boom is quite startling; I certainly wouldn't want to endure them regularly. I know because booms from fighters were common during my trip to West Germany in 1970. (I'm relying on what locals told my parents as to the source of the booms: I never saw a plane.) I've never heard a sonic boom in my 60 years of living in the US.
Re:Will we ever fly supersonically over land? by Mountain_Skies on Saturday July 03, 2021 @08:50PM (#27726408)
Rural Alabama had them semi-frequently in the late 70s and early 80s. Not sure where the fighters came from, perhaps Maxwell AFB had a training wing at that time. As far as I know, it never broke anything but it sure would rattle your dental work.
Re:Will we ever fly supersonically over land? by paul_f on Saturday July 03, 2021 @09:21PM (#27726569)
You are correct. I clearly remember hearing sonic booms in Montgomery, AL in the early 70s.
Re:Will we ever fly supersonically over land? by dreamcompiler on Saturday July 03, 2021 @11:48PM (#27727090)
I used to hear them all the time in Texas when I was a kid in the 70s. We were fairly close to an air force base and we'd be out in the yard on a bright sunny day when we'd hear a thunderclap, as if lightning had struck less than a mile away. We'd look up, see a contrail, and say "Oh." It never caused any damage; it was just surprising.
Re:Will we ever fly supersonically over land? by LinuxBender on Saturday July 03, 2021 @11:31PM (#27727027)
I heard them all the time near Vandenburg AFB in the 70's and early 80's. I don't remember when exactly I stopped hearing them.
Re:Will we ever fly supersonically over land? by nine_k on Saturday July 03, 2021 @08:03PM (#27726074)
I don't see why the boom energy has anything to do with the size of the aircraft producing it. It should only depend on the speed of the spike that produces the boom; typically the entire aircraft fits within the sonic boom cone produced by the nose spike when flying straight.

So I suppose an artillery shell, a jet fighter, and a Concorde should produce about the same amount of boom at the same speed of, say, 1.5 M, while flying by.

The engine sound of the aircraft, though, can add significantly to the noise in the wake of the boom cone. Those engines are not low-power or quiet.

Re:Will we ever fly supersonically over land? by kortex on Saturday July 03, 2021 @08:11PM (#27726110)
Why wouldn't size correlate with magnitude? A whip crack breaks the sound barrier, it doesn't shatter windows. Same with a bullet, which goes even faster.

You need both pressure level (voltage) and momentum (current) in order to stay strong over distances (shock waves diffuse over time) to break windows. Small, super fast things create large pressure differentials, big jets create more momentum.

Re:Will we ever fly supersonically over land? by lazide on Saturday July 03, 2021 @10:29PM (#27726828)
Because the Mach cone produced by the leading edge/cone keeps most of the air from interacting with the aircraft behind it. It’s in the ‘wake’ as it were, though there may be multiple Mach cones or non-‘cone’ shaped ones depending on the shape of the aircraft.

This does cause some stability or handling issues for the aircraft.

The analogy re: voltage or amperage are spurious and just don’t apply here.

Re:Will we ever fly supersonically over land? by vilhelm_s on Sunday July 04, 2021 @12:50AM (#27727302)
Surely the air is still interacting with the airplane.

The shockwave generated by a body shaped like an acute cone is a (somewhat less acute) cone with the same apex. Inside the shock wave, the air gradually turns around to move parallel to the body, like so [0]. Each streamline that enters the shock structure keeps turning around, so each bit of air keeps feeling a force even after it passes through the original cone-shaped shock. In the case of a cone-shaped body, the interaction happens to create a single "straight" wave, but it's still generated by the entire surface of the cone, not just the sharp point of it.

As a rule of thumb, the magnitude of the sonic boom is proportional to the weight of the plane. That is because most of the interaction between the plane and the air is from the wing, it needs to continuously deflect down enough air to generate a lifting force. So the total boom has one contribution from the cross-section of the fuselage, and another from the wings, and the latter is determined by the weight.

[0] https://www.researchgate.net/profile/Richard-Benay/publicati...

Re:Will we ever fly supersonically over land? by lazide on Sunday July 04, 2021 @11:28AM (#27730390)
sub-sonic, trans-sonic, and supersonic aerodynamics are fundamentally different. You’re calling out some differences, but not covering others.

They are wildly, fundamentally different in behavior.

You’ll notice that supersonic aircraft have different airfoil shapes, different airframe shapes, and wildly different engine configurations because they don’t work the same way.

There is of course air behind the Mach cone, but it is much lower pressure, will often completely separate (airflow wise) from the airfoil shape in ways you would not expect, and the shockwaves/speed of propagation can cause bizarre pressure, lift, and drag issues. You can end up with massive vacuum where you previously had pressure, or pressure where you preciously had vacuum. Transonic flight or high angle of attack flight at supersonic speeds of course produces rapidly changing variations of all these effects.

[https://arc.aiaa.org/doi/abs/10.2514/8.1394?journalCode=jans]

Unlike subsonic flight, the air can’t “get out of the way” in time, leading to potentially catastrophic issues without careful design. Supersonic flight is better categorized as ‘shoving through slow air’ than flight.

What you’re referring to is not wrong - just doesn’t reflect the magnitude of the actual differences