Today I had a go at recording the sound of the starting, running, and stopping of my engine. The resulting MPEG Audio Layer 3 file jet1.mp3 (142k) can be downloaded for your amusement. It is a 22kHz 8 bit mono sample approximately 40 seconds long. The buzzing noise audible at the start for a couple of seconds is the noise of the spark ignition. The thud a few seconds after the air jet starts is the moment I turned on the gas and it ignited. Unfortunately, the cheap tape recorder I used overloads on loud noises, and mutes the mic input briefly at this point. The recorder was placed about 2m behind the engine, and off to one side.
The run brings the engine up to a speed of about 20000 rpm, holds it there for a few seconds, and then spins down after I turn off the fuel supply.
I must apologise for the sound quality, as it is not particularly good. The only tape recorder I could find that worked is about 15 years old, and rather ill. I will try to produce a better recording if I can borrow a friends DAT recorder and a good mic at some later date.
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