Timeline for Is it possible for an airplane on the sky to play a sound so loud it could be heard 50km away?
Current License: CC BY-SA 4.0
31 events
| when toggle format | what | by | license | comment | |
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| Jan 11, 2023 at 1:05 | comment | added | Azor Ahai -him- | @SnakeDoc I think you are thinking you wrote "In US aviation," when you didn't, you said "in the US," which implies that as a rule, Americans start saying "FLXXX" at a certain point. Anyway, we don't need to keep going around on this. | |
| Jan 10, 2023 at 17:42 | comment | added | SnakeDoc | @AzorAhai-him- Then you misunderstood. In the US, the transition altitude is 18,000ft, which is what would be called FL180. Other countries have a different transition altitude. Airplanes transition into flight levels so that spacing is standardized - this allows aircraft to safely pass above/below others. Flight levels technically go all the way down to 0ft altitude, ie. FL000. A layman probably would not refer to altitude as a flight level, you are correct. It was more informational than anything. Adding accuracies to our fiction is a good thing. | |
| Jan 10, 2023 at 3:08 | comment | added | Azor Ahai -him- | @SnakeDoc You said "Also, in the US ..." and I was disagreeing with you that Americans would say FL600. | |
| Jan 9, 2023 at 19:10 | comment | added | SnakeDoc | @AzorAhai-him- That depends entirely on the type of fiction the OP is writing. We're asking people to suspend their disbelief, and minor inaccuracies add up and break the illusion for readers. Accuracy, even in fiction, if always a good thing. I would agree, laymen wouldn't reference flight levels - but aviators (military and civilian) might. Depending on the character and their perspective (and who they are talking to), one might be more appropriate than the other. We might even use both in different situations, different characters, etc. | |
| Jan 8, 2023 at 5:03 | comment | added | Azor Ahai -him- | @SnakeDoc Pilots might, but the random person on the corner would never say, "where a plane at FL600). | |
| Jan 7, 2023 at 14:51 | comment | added | Hagen von Eitzen | @JBH Perhaps the OP should switch to subliminal sound, which might have the desired psychological effect without anybody even noticing it? Then again, 0.004 dB is of course too small for that as well ... | |
| Jan 7, 2023 at 14:47 | comment | added | Hagen von Eitzen | We should ask Hotblack Desiato for some hints how to achieve the desired effect ... | |
| Jan 6, 2023 at 21:16 | comment | added | user3445853 | Isn't it just the low frequencies that can travel (that) far? So the resultant noise wouldn't be intelligible. Like the only noise you hear from a distant party is the thump-thump-thump bass, none of the voice/high frequency/melody? | |
| Jan 6, 2023 at 19:17 | answer | added | Tetsujin | timeline score: 3 | |
| Jan 6, 2023 at 18:21 | comment | added | Jeremy Friesner | Note that the high frequencies will attenuate quickly with distance, likely leaving only the low frequencies audible to people on the ground. The device might end up sounding more like thunder than anything else. | |
| Jan 6, 2023 at 14:06 | answer | added | fectin | timeline score: 3 | |
| Jan 6, 2023 at 6:13 | comment | added | JBH | @AustinHemmelgarn I don't know where the 200dB was measured, but let's assume we need the LRad sonic weapon intensity of 160dB on the ground, 50 Km away from the source, which is traveling at some unknown speed (might need to know that). Sound diminishes with the inverse of distance, so the XF-84H producing (I assume) 200dB at 1m from the engines would diminish to 1/50000 = 0.004 dB at the target (that seems really low, someone check my math). If for some reason that's right (seems low), then to hit 160dB the source needs to be 8MdB (that's gotta be wrong). Where's my physics book? | |
| Jan 6, 2023 at 4:29 | answer | added | Nelson | timeline score: 3 | |
| Jan 6, 2023 at 3:05 | comment | added | Austin Hemmelgarn | Rereading the question, I feel compelled to point out that 15km is actually rather high altitude for a crewed fixed-wing aircraft. About the only production aircraft that can operate that high are military recon aircraft (such as the SR-71 or U-2) and a handful of fighters. There is a relevant Aviation.SE question that may be of interest here. | |
| Jan 6, 2023 at 1:33 | comment | added | SnakeDoc | Very minor nit-pick on the question, since you're writing a story. We would refer to it as being "at" altitude, not "on" altitude. Example, "The plane was flying at 8,000FT", or "The plane's altitude was 8,000FT". Also, in the US, we switch to Flight Levels at 18,000FT (which is FL180) as a way to standardize things like spacing (some other countries switch at different altitudes). Your example would become: "where a plane at Flight Level 600 (FL600)" or "where a plane at an altitude of 60k ft". | |
| Jan 5, 2023 at 23:53 | comment | added | Cadence | At risk of belaboring the obvious... if your pilot could wear hearing protection effective against such a phenomenally powerful sound, so could the troops on the ground. | |
| Jan 5, 2023 at 23:16 | answer | added | Corey | timeline score: 5 | |
| Jan 5, 2023 at 22:14 | comment | added | David Ljung Madison Stellar | I find it amusing that in this world they've developed some pretty incredible speaker technology, but not ear plugs. | |
| Jan 5, 2023 at 21:12 | comment | added | Austin Hemmelgarn | @AlexP True, but at the scale involved we’re talking about shock waves at the point of origin anyway. There’s just no other way to get the pressure high enough to ensure things are audible that far away. | |
| Jan 5, 2023 at 21:09 | comment | added | AlexP | @AustinHemmelgarn: A sound wave cannot go to more than 194 dB SPL in air at 1 atmosphere pressure, because pressure cannot go below zero. (And those 194 dB SPL are purely theoretical, in an ideal model; in reality, the behavior of the air becomes very non-ideal as sound waves go beyond 150 dB SPL.) Explosions and sonic booms can of course be stronger, but they are shock waves, not sound waves. | |
| Jan 5, 2023 at 21:03 | answer | added | Robert Rapplean | timeline score: 2 | |
| Jan 5, 2023 at 20:52 | comment | added | DKNguyen | But why? If you can produce such loud sounds and project them over long distances you might as well just play those sounds a little closer up and make all the enemy combatants deaf. | |
| Jan 5, 2023 at 20:27 | answer | added | G. Putnam | timeline score: 16 | |
| Jan 5, 2023 at 19:37 | comment | added | Austin Hemmelgarn | @JBH Not necessarily. The XF-84H Thunderscreech managed 200 dB and a 25 mile (~40 km) audible distance during ground runs, and it was a tiny little fighter/bomber. The hard part here is producing anything other than either rumbling or a very loud bang, though in theory maybe you could modulate the engine speed to replicate sounds (fidelity would be seriously horrendous, but I’ve actually seen even stranger things done before to create ‘music’). | |
| Jan 5, 2023 at 17:51 | comment | added | reirab | One thing that will be working against you here is the stated altitude. Air is much, much thinner at 60k ft than at sea level. About 1/14. As such, sound does not propagate nearly as well at that altitude as it does near sea level. | |
| Jan 5, 2023 at 17:09 | comment | added | JBH | In fact, now that I think about it, a low frequency wave of that magnitude might require the plane to be in a power dive just to have something to push against to create the wave in the first place. For every reaction there's an equal and opposite reaction. | |
| Jan 5, 2023 at 17:07 | comment | added | JBH | Sound is a compression wave in the atmosphere that our ears interpret. Think of a speaker moving back and forth. That's what it does, it pushes air in waves. A low-frequency wave of the magnitude you're talking about would push the plane higher into the atmosphere or simply cause it to crash. A high frequency wave wouldn't, but it would also weaken very quickly. In the long run, the idea is probably plausible (kinda...), but for one problem. The size of your power generator would likely be bigger than the plane itself. You'd need an aircraft carrier with multiple dedicated nuclear reactors. | |
| Jan 5, 2023 at 16:39 | history | became hot network question | |||
| Jan 5, 2023 at 9:12 | answer | added | user86462 | timeline score: 21 | |
| Jan 5, 2023 at 8:46 | answer | added | Separatrix | timeline score: 9 | |
| Jan 5, 2023 at 8:39 | history | asked | Titanium Steel | CC BY-SA 4.0 |