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Comment by t0mas88 | Hacker News Reader

> These studies, along with tens of thousands of claims against the Air Force for property damage—horses and turkeys had supposedly died or gone insane—led the F.A.A. to ban civil overland supersonic flight, in 1973.

There was also a political part involved. The Concorde was a British-French creation, not a Boeing. Had there been a Boeing supersonic passenger plane first there would probably have been different FAA rules. Especially because military supersonic flight happens every day over US land, was never banned, and causes the same boom.

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Europe banned continental supersonic flights too which is why only the Atlantic route to NYC was an option you couldn’t do flights eastward.

Strap a 22 year old into a machine worth hundreds of millions, WCGW?

As I recall they also briefly had routes to VZ and BR

Military supersonic flight over land in the US only happens over unpopulated areas. Ie, parts of Idaho, Nevada desert etc. Most supersonic training is conducted over the oceans, eg >15nm from the east coast.

Military supersonic flight over land in the US is supposed to only happen over unpopulated areas. Having lived near a coastline (~1 mile from the shoreline) along a military flight path, I know they occasionally went a little early.

How loud was it and how often did you experience it?

They did it near London once by in error. One little Typhoon can produce an unbelievably powerful sonic boom. I felt it as a loud crack/thump on my roof. Now, imagine a Concorde going supersonic...

It happens in the Lake District and Wales reasonably often. Often the pilot/crew will go out and apologize to a farmer. Sometimes livestock allegedly die, although I'm not sure what the mechanism is.

Best childhood memories are from doing walks in the Lakes and having jets zip past in the valleys below. Insanely close, too — I distinctly remember seeing the pilot’s visor and making out white text on the side of the aircraft.

Is the Lake District the infamous “Mach loop”?

No - the Mach Loop is in Wales. Although as the jet flys, they're not far off - so it's common to do lowfly training missions that include both. The loop has a number of aviation enthusiasts who reside there. They'll hear jet noise (or listen on the radio...), then call their friends, get out of their houses, and watch / snap pics of the planes.

I've had similar in Wales. I once got the shock of my life when a jet roared probably not more then 100 foot over my head.

That mechanism is trying to get compensated for dead live stock and pulling straws. Thunder is a sonic boom. It’s like saying thunder killed a cow.

very loud sounds can panic/shock animals and if it's too much for them, they die.

Well, in that case, when will we start jailing bikers with loud exhausts for the deaths of old people from heart attacks?

Many places do regulate the noise levels of exhausts, which seems a bit more appropriate and less punitive than permitting any exhaust and hoping people don't die as a result. The penalties for noncompliance are obviously not as high as jail time, but at least to me, (among other things) there is an element of premeditation or willfulness missing in these deaths.

God that would honestly be a dream come true actually

I dream of a day when light and noise pollution are taken seriously. Its exhausting walking beside a busy road with the roar of traffic. You see the birds don't even bother to try and sing anymore. They are just silent and isolated until they get further away. Visual pollution from advertising would be great to curb as well.

Is there documented proof of this actually happening?

Rural person here from Wales where sonic booms from military aircraft were moderately common.

Animals panic when they hear the boom: they tend to stampede, fall off cliffs, break legs, trample each other, lambs get separated, break through hedges and into traffic.

The booms were severe enough to occassionally shatter the Royal Doulton in the house, much to my mother's disgust.

If I recall correctly. The recent examples of Typhoons going super sonic over London were QRA aircraft hammering it down the country to pick up suspicious aircraft. In some of those cases they are allowed do it

F-104 going supersonic at something like 500ft or slightly lower within less than a mile feels like a full body slap which makes the parts of your clothing which are not tight flutter. Anything a few thousands feet up is still very loud but doesn't do the slapping and fluttering anymore. Anything a few 10.000 feet can still be very loud. Though it varies. Don't know on what it depends exactly. Had 4 in row making nice contrails high up, rather soft. Had single ones, also high up, making a contrail, banging loud and sharp, thinking why was that? Those are all memories from the 80ies. Can't remember when I heard the last supersonic boom anymore. Has to be early 90ies. Today I laugh when I read about people calling the emergency services when they heard one ;-)

Didn't have a decibel meter, but pretty loud, rattled the house and windows. Not as bad as someone using tannerite, though it might just be that the tannerite is a relatively recent experience and the sonic booms were a while ago.

Depending on the jet, accidental supersonic can be easy/common, or rare. (eg a strike eagle with the older engines won't go super unless you're trying)

Indeed it was political. IMHO if a US supersonic commercial plane comes into service without an Airbus counterpart, it won't have access to the European skies. At least not the over french territory. The industry is still very salty that the Concorde market was taken from under them.

Europe banned supersonic commercial flights over the continent 2 years before the US did.

Whilst this was political to some extent the politics were very much local, as in people don’t want to hear booms.

Also, shattered windows. A boom can easily smash windows.

Especially 100 year + old buildings with original glass.

Not that easily. Even with a fighter at 500 ft above, Mythbusters couldn't break windows. The Oklahoma tests had eight booms a day using very large aircraft. It took months before windows broke.

Long term wear and tear is a legitimate concern.

I’d be pisses if jets flying overheard broke my windows once every five years.

The Space Shuttle's sonic boom broke one of my bay windows when I was living in Orlando. Mythbusters was an entertainment TV show, I wouldn't extend their results to real life.

not really the same, fighters are quite smaller than airliners.

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.

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.

You are correct. I clearly remember hearing sonic booms in Montgomery, AL in the early 70s.

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.

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.

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.

I wonder if the comparison would be more frontal area than weight?

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.

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.

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.

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...

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

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