3 ms·
We have planes pass overhead at about 6000ft. When the conditions are right they'll make a completely different sound, I've always assumed it's the Doppler effe
by roygbiv2 1y ago
We have planes pass overhead at about 6000ft. When the conditions are right they'll make a completely different sound, I've always assumed it's the Doppler effect mixed with the valley we live in but I'm always very curious when it does happen.
They make their usual sound but then there's a second sound that arrives, a lot higher pitched. Sounds like they've struck it in reverse or something (they haven't they're just doing a normal decent).
- kpil 1y agoExtending flaps for approach makes a rather distinct woosh going from high to low pitch over a few seconds.
- ano-ther 1y agoVery interesting question. I thought that was when they extend their flaps so the wings become a bit wider for the slower flight and that creates some resonance.
- roygbiv2 1y agoMmm could be. I need more data. Eg is it when landing on one runway or are they going to the other one, cloud layers etc.
- oe 1y agoI think it’s some engine type that makes the sound at some specific speed / throttle setting. But I can’t remember the specifics. Some planes passing us make the sound, most don’t.
- LargoLasskhyfv 1y agoCould also be FOPPs, or both combined! (Fuel Overpressure Protection) https://aviation.stackexchange.com/questions/23701/what-causes-descending-aircraft-to-make-a-noise-like-a-giant-blown-bottle https://aviation.stackexchange.com/questions/23701/what-caus... Some do it at certain airspeeds, others don't. Depends on their shape, and can be mitigated/eliminated, which is sometimes done, other times none.
- philipwhiuk 1y agoSound is also reflected off a cloud layer if present.