5 ms·
SpaceX Starship's Sonic Boom Creates Risk of Structural Damage, Test Finds
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- mhb 2y agoI need a guy like this to investigate the leafblowers across the street.
- perihelions 2y agoEh bien! qu'elle saute!
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- mtreis86 2y agoI would have expected it to be the takeoff making all the noise. 105db at takeoff but 144db when the booster returns is what, almost 10,000 times louder at peak? I wonder what will have to be done to mitigate it, take more fuel up and slow down earlier?
- yencabulator 2y agoTake-off makes a lot of noise, but the noise doesn't reach the observer on the ground the same way. https://youtu.be/liKe0kg3agY?t=582 https://youtu.be/liKe0kg3agY?t=582
- fidotron 2y agoUnsurprisingly the paper is more interesting: https://pubs.aip.org/asa/jel/article/4/11/113601/3320807/Starship-super-heavy-acoustics-Far-field-noise https://pubs.aip.org/asa/jel/article/4/11/113601/3320807/Sta... “Notably, a supersonic Concorde flying at an altitude of 18 km produced a sonic boom with a PL of ∼105 dB at the ground. With a difference of 5 dB, one approximation for a Starship flyback boom at 20 km is a ∼50% increase in loudness over the Concorde boom (where 9 dB represents a loudness doubling; see Stevens, 1972).”
- delichon 2y agoI thought it was logarithmic and it doubled for each 10 db. Why 9 db? Lots of confusion online about this but 9 db isn't one of the values mentioned much. This piece says sound pressure doubles each 6 db: https://sengpielaudio.com/calculator-levelchange.htm https://sengpielaudio.com/calculator-levelchange.htm
- Bjartr 2y agoThe paper they reference[1] is a paper that describes an approach to formalize human perception of loudness. This is distinct from the sound pressure due to the construction of the human auditory system. Here's the relevant excerpt, but you'd have to read the paper to see why they claim this as accurate. > The perceived magnitude (loudness or noisiness) grows as the 2/3 power of the sound pressure, so that perceived magnitude doubles with each increase of 9 dB. [1] Stevens, S. S. (1972). “ Perceived level of noise by Mark VII and decibels (E),” J. Acoust. Soc. Am. 51(2B), 575–601.https://doi.org/10.1121/1.1912880 https://doi.org/10.1121/1.1912880 Available in full from sci-hub
- blankx32 2y agohttps://archive.ph/K4YGR https://archive.ph/K4YGR
- tzs 2y agoNote that the sonic boom is not from the launch, but rather six and half minutes later from the booster returning. Rockets do make sonic booms on launch when they go supersonic but the shockwave travels forward and out. Generally unless something has gone very very wrong most rockets are launched upwards so generally people behind the rocket won't hear a sonic boom. > Terracon found a peak sound pressure level of 144.6 decibels as the rocket descended, which is also higher than Port Isabel expected, said the city manager, Jared Hockema That's loud. NIOSH recommended exposure limits are 8 hours at 85 dB(A), and for every 3-dB over that cut the time limit in half. For 144.6 dB (assuming it is dB(A)...the article just says decibels) the exposure limit would be 30 ms. It's not clear though if that halving the time per 3-dB increase rule is applicable at the point. 144 dB looks like it might be above the threshold were there is instant hearing damage. Anyway, how can they mitigate this? Since the problem is the returning booster could they change the flight profile so that after the booster separates it slows down to subsonic speed before it starts coming down?