[AR] Re: BFR Noise
- From: Ben Brockert <wikkit@xxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Fri, 30 Sep 2016 07:24:44 -0700
On Fri, Sep 30, 2016 at 7:05 AM, Nels Anderson <nels.anderson@xxxxxxx> wrote:
Are there any mitigating factors? Might the gas-on-gas Raptor be
fundamentally quieter than the liquid-on-liquid F-1? I recall a claim
by Firestar that mixing affects noise.
The video they showed did have very stable chamber pressure, so at
least the engine wouldn't be adding additional noise on top of the
noise of hypersonic gas tearing into still air.
Another mitigating factor may be trajectory. The noise from a rocket
has a significant directional component, they're quite a bit quieter
to the side than to the back. With a plan to RTLS, the trajectory of
the BFR would optimize to more vertical than the trajectory of a
Saturn V. In the end that might just mean that it's louder longer in
Titusville and quieter in Orlando, which counts as a bit of a win.
The sonic booms might be the larger issue. People here are used to
launch noise, though if someone started launching daily I expect
they'd be restricted to daylight hours. Great big sonic booms aimed at
the coast are another thing. The shuttle boomed the area, but it was a
fairly weak boom over a large area. This thing will be aiming the
world's largest sonic boom directly at the launch site and the
surrounding communities. Booms are a lot more startling than the
rumble of a launch.
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