--- Geoff Branch <gjbranch@comcast.net> wrote:
> Why is aircraft electricity such high frequency?
Because they don't drug test them?
It's commonly wild frequency now, btw. But it was done
initially to save weight, as power supplies can be
made smaller, albeit less efficient.
> And for a bonus question: What are those little
> "donuts" of blue in the
> exhaust of high speed aircraft such as the SR71??
Mach diamonds, a cool phenomenon of the exhaust gases
being at a significantly different pressure than the
ambient. AKA "overexpansion" when the exhaust pressure
is lower than ambient at low altitudes. Technically,
they are Prandtl Meyer (SP?) waves.
Anyway,
Ron
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