The 'war tubas' we used to spot warplanes before radar (2018) | Hacker News Reader

The 'war tubas' we used to spot warplanes before radar (2018)

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61 pointsTomte24 comments

Now I want to hear "Minuet in G for War Tuba" :-)

One of the more interesting things about sailing on Lake Mead outside of Las Vegas was that when conditions were right you could hear people talking on the beach more than a mile away. That you could weaponize this phenomena seems pretty obvious in hindsight.

I love how sound carries over water. As a child, I used to sit on a dock on a small lake, and I could see the beach somewhere between half a mile and a mile away, and they would play volleyball. I could hear each noise as the ball was bumped, noticing how the sound was delayed after the viewing of the ball hit. I was totally amazed thinking, "I've just noticed the difference between the speed of light and the speed of sound."

Good times.

Any idea why they're all pointed in the same direction, rather than different directions, in photo 4/10?

https://dynaimage.cdn.cnn.com/cnn/q_auto,w_1100,c_fill,g_aut...

You don't want to scan two angles at once. Direction is determined by probing different angles, not by the difference between two angles.

From the article, it seems like the four horns on each individual unit are enough to do the triangulation.

Looks like San Francisco, so I assume it's an exercise and perhaps they're all tracking the same friendly plane.

Would this still work for modern military aircraft? I wonder if this + machine learning might still be useful, given radar stealth.

I think much of the usefulness is tied up into the sound arriving substantially before the plane itself.

Or you have a network of sensors?

Many of modern aircraft is supersonic so acoustic detection would be useless, even if it technically works.

True (though stealth bombers are subsonic, just). What about headings that are not straight at you though? May still have value detecting things passing by?

When I was at military I attended a few exercises where jets were involved. They don’t go supersonic but pretty close to it so usually once you start hearing something it’s almost over. It’s actually quite terrifying to have a jet coming at you at 800 km/h at low altitude. Very surprising, then very loud and incredibly fast. You also hear passing by jets only once they are long gone. I assume radar is just much better than sound.

Not just jets, a regular propeller based plane can have that effect:

https://www.youtube.com/watch?v=4iOoiEbtf2w

Now double or triple the speed, make it much louder and you have a jet.

Most do not have supercruise, so they would spend most of their flight at high subsonic speeds.

Then it becomes a battle between the detection range of the audio sensors vs how long the attacking craft can spend supersonic. They could spend the last phase of the approach supersonic and even transition then turn to make any tracking useless.

If they are supersonic, would you just need to increase how much you lead the weapon. Supersonic doesn't mean they're quiet, they're just further ahead than where you are hearing them. Or am I just totally making stuff up?

Detecting helicopters would be one situation where it could be useful for mobile troops on the ground.

One of my favorite bands has the wearable-size version on the cover of an album.

https://en.m.wikipedia.org/wiki/Hello_World_(Information_Soc...

When I played Bioshock Infinite (2013) I had wondered if the Boys of Silence were conceived based on this idea.

https://bioshock.fandom.com/wiki/Boy_of_Silence

These structures might very well have non-military (peaceful) applications for physics experiments involving sound...

Sort of like what observatories are to light... these structures might be to sound...

I'm kind of disappointed I have never seen these in any movies before. I'm thinking they would have specifically gone well with the recent Man In High Castle series.

very interesting. still could be useful against drones, especially as drones get used more and more in espionage and reconnaissance

The next iteration, sound mirrors, were featured on Tom Scott.

https://youtu.be/04F5osXK4vw

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