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Nobody seems to be talking about the sonic boom issue. People often assume that the sonic boom is a single event that happens when the plain exceeds the speed o
by dhosek 6y ago
Nobody seems to be talking about the sonic boom issue. People often assume that the sonic boom is a single event that happens when the plain exceeds the speed of sound, but rather its a continuous event that happens at supersonic speed which is why the Concord was used only for transatlantic service. A supersonic plane would not be practical for any overland route.
https://en.wikipedia.org/wiki/Sonic_boom https://en.wikipedia.org/wiki/Sonic_boom
- tachyonbeam 6y agoIs it very loud even when planes are over 30,000 feet altitude? Can supersonic planes easily cruise at subsonic speeds when preparing to land?
- rbanffy 6y agoThey do, but the wings have a lot of drag that the engines must compensate for.
- dhosek 6y agoFrom the linked wikipedia article: >In the late 1950s when supersonic transport (SST) designs were being actively pursued, it was thought that although the boom would be very large, the problems could be avoided by flying higher. This assumption was proven false when the North American XB-70 Valkyrie started flying, and it was found that the boom was a problem even at 70,000 feet (21,000 m). It was during these tests that the N-wave was first characterized.
- rbanffy 6y agoThe Overture is smaller than the Concorde, so that a lower level of noise is expected. There has been some developments in aerodynamics for minimizing the shock by spreading it over a larger area, but, as you point out, they don't mention it. It is probably part of their "secret sauce".
- liability 6y agoAnother difference between the proposed Overture and the Concorde is the engines. Concorde used turbojets with afterburners during takeoff, while Boom proposes a turbofan design without afterburners, which should in theory make it quieter for communities adjacent to airports. However the XB-1 small scale version will use turbojets according to Wikipedia.
- praveen9920 6y agoim not sure if they will be commercially successful but the technology sure seems like it is much more valuable than actually building a plane and run operations
- rbanffy 6y agoTrue, but I would imagine engine noise to be a relatively small part of the sonic boom issue.
- liability 6y agoI think you're right, though take-off noise was also the subject of many complaints about the Concorde, not just the sonic boom. Reducing take-off noise was already one of the design considerations of the Concorde, and supposedly the Concorde was better in this regard than the Russian Concordeski (Tu-144.)
- tomatocracy 6y agoI saw Concorde taking off a few times up close at air shows when it was still in service. It was significantly louder than any other aircraft I've ever been near (it had 4 enormous engines with afterburners - not that surprising I guess). Takeoff noise really was a big issue.
- soylentcola 6y agoIt used to fly over my house when I was a teenager. I lived an hour or two (drive) from Dulles Airport and when it (rarely) passed overhead, it was still fairly loud. Nothing like you'd hear at an air show, but we always knew to look up if we heard it when we were out in the yard. It was pretty cool because it was close enough to takeoff that you could easily make out the distinct shape of the plane.
- liability 6y agoThe premise of Boom Technologies is that the intensity of the sonic boom can be managed by creating an aircraft with a sufficiently clever shape. I don't know exactly how that's meant to work, but it's this premise that they hope to demonstrate with the small-scale XB-1 in 2021.
- andi999 6y agoCan one short sell a non listed startup?
- liability 6y agoI don't think they're going to be a commercial success, but I don't really have a reason to doubt the possibility of new supersonic aircraft being quieter than older ones. Is there some particular reason to doubt this aspect of Boom's proposal?
- andi999 6y agoThe supersonic boom basically comess from the medium and nobody has been able to get rid of it. So the boom is not an engineering problem but a physics problem. Startups can solve engineering problems but rarely invent new physics (which might exist, mind you). So this new product will be limited to the same routes as concorde (plus pacific if they manage extra long haul).
- liability 6y agoThe supersonic boom comes from the interactions between the aircraft and the medium, not from the medium itself. I think it stands to reason that the properties of the boom can be manipulated by manipulating the properties of the aircraft's shape. It's not even controversial that some aircraft design elements can reduce the intensity of sonic booms, the only question is whether Boom has enough know-how to achieve the house levels they promise.
- renewiltord 6y ago
- bananabreakfast 6y agoAlmost all of the research on sonic booms and their effect on residential noise levels was done in the 1950s. Our knowledge of transonic aerodynamics and aircraft design have improved considerably sense then and much of the "common" knowledge that sonic booms will shatter windows and disrupt everyday life as a plane flies overhead at cruising altitude are very much outdated.
- dhosek 6y agohttps://en.wikipedia.org/wiki/Shaped_Sonic_Boom_Demonstration https://en.wikipedia.org/wiki/Shaped_Sonic_Boom_Demonstratio...
- rozab 6y agoConcorde wasn't that long ago. Londoners still remember.
- gsnedders 6y agoConcorde didn't fly over London at supersonic speeds, and I doubt it often flew over London a cruise altitudes. The problem with Concorde on approach/departure was largely a function of its engines, rather than speed. https://hansard.parliament.uk/Commons/1973-07-18/debates/4279b473-5235-41e3-923e-580f3df10e57/Concorde(NoiseLevels) https://hansard.parliament.uk/Commons/1973-07-18/debates/427... shows it was comparable to slightly older aircraft at the time of introduction (VC10, B707, DC8) but notably louder than what was arguably its biggest competitor (747-200). In later years, continued improvements in aircraft noise pollution meant the margin between Concorde and other aircraft operating out of LHR just grew larger and larger.
- warmcat 6y agoI am fine with an aircraft which takes me supersonic over Atlantic/Pacific and then switches to subsonic over land on my way to Asia.