| Topic: | Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:Re:3rd runway noise in Chiswick | |
| Posted by: | Jeff Gear | |
| Date/Time: | 07/02/08 12:51:00 |
| Tom, I do have faith in the inverse square law. I believe that would be the one that predicts the sound of a plane over Chiswick at 650m to be about 3 times louder than a plane over Battersea Park at 1100m. I don't have faith in DfT predictions of 54dB Leq over Chiswick with a third runway. I believe that the noise level experienced in Stavely Gardens (an otherwise quiet residential road) while a stream of twin engine medium sized aircraft bound for the northern runway pass over is a good representation of the noise levels my bit of Chiswick would experience with a third runway. That noise level would be a problem for some (including me) but not for others. The scepticism has several drivers: While it's not hard to discount the noise of big 4 engine planes while assessing noise levels, it may not be wise to do so. The projected length of the third runway has already grown from 2000m to 2500m. Given the history of broken promises on (no) further expansion of Heathrow it would not be even remotely suprising if it turned into a full length runway capable of handling all aircraft. Similarly I'm afraid, for any pattern of usage posited for the 3rd runway, it ain't necessarily so... Perhaps more importantly though, I'm not convinced by the idea that most aircraft will be quieter than todays' when a third runway became operational. Driven largely by the quest for fuel economy, the latest models are quieter than those of say 30 years ago. But it seems likely to me that the easily achievable quietening has been done, and that further reductions of noise level would require radically different aircraft design. For example, I think ground noise would be lessened if wings were much wider front to back (plan view), with the engines on pylons above the wing rather than below. However, radical redesigns are not going to happen unless they are more fuel efficient, and certainly wouldn't be in service by 2020. I guess that buried in the middle of a long thread not too many people are going to be reading this, but hey, your turn! |