Originally posted by Arbitrageur I never saw any Auroras or FB-22s fly overhead like the common jets, so I can't make a personal
confirmation of this sound reduction, but if somebody else has maybe they can confirm if my guess is correct that they are not as loud, and maybe even
quiet enough to not be heard in a thunderstorm, especially if only using a fraction of maximum power.
I found an additional possible explanation for the sound reduction:
The winds associated with the thunderstorm. These folks have done some research into cases where people have seen helicopters flying overhead and have
not heard the helicopter sound in certain windy conditions:
www.caelestia.be...
So we have four factors to consider regarding the sound:
1. The possible "muffler" effect of burying the engine inside the aircraft and mixing the exhaust with fresh air to reduce the infrared heat
signature may also reduce the sound level.
2. The attitude and maneuvers photographed do not require full power and we know jet engines make less noise at reduced power levels.
3. The wind may be carrying a large portion of the sound away from the observer, drastically reducing the perceived sound.
4. Whatever residual sound reaches the observer's ears as a result of the above 3 factors is not loud enough to be heard over the ambient
thunderstorm sounds, sort of a signal to noise ratio issue. The person who took the photographs raised this point so we have to give it some weight
accordingly.
So maybe between these factors combined with the unknown distance, the lack of sound being heard by the photographer doesn't rule out a jet-powered
aircraft, like the FB-22.
[edit on 16-6-2009 by Arbitrageur]