Lovely stuff, Jim
That diverted me through the Whitcomb page, the F101, F102, F106, F89 and Genie
pages :-)
Among several wastes of weight, space and money on the Tornado was the intake
ramp of each engine. It was required for use above M1.4, but we were never
going to go that fast at low level, which was the intended flight regime.
Another waste of the same was the swing-wing design, which should have gone out
with the F111.
Chris
> On 16 Dec 2016, at 16:09, Jim Nichols <jhnichols@xxxxxxxxxxxxx> wrote:
>
> The answers to your questions would constitute at least a one-semester course
> when I was in college. I'll try to make it a "short course".
>
> As an aircraft reaches the speed of sound, Mach 1.0, the resulting shock, or
> compression wave, is nearly vertical, and the wave drag is near its maximum.
> You've probably seen some of the popular photos of aircraft with the front
> half encased in a condensation wave. As the speed is increased further, the
> compression wave sweeps back in accordance with the Mach angle relationship.
> I can't locate NACA Report 1135 right now, but here is an on-line reference
> to the relationships:
>
> https://www.grc.nasa.gov/www/k-12/airplane/machang.html
> <https://www.grc.nasa.gov/www/k-12/airplane/machang.html>
>
> A quick example shows that, while the Mach 1.0 shock is vertical, or 90
> degrees, by the time a supersonic aircraft reaches Mach 2.2, the shock angle
> has decreased to 27 degrees, and the wave drag is much less.
>
> Wave drag IS sensitive to body shape, as you would imagine. NACA did a lot
> of work in the 1940s to develop optimized shapes. Their famous "Coke bottle"
> fuselage shape was an effort to smooth out the volume of the aircraft from
> front to back, so the fuselage diameter was reduced in the wing attachment
> area to compensate for the volume of the wing. Here is a reference to
> Whitcomb's famous area rule:
>
> https://en.wikipedia.org/wiki/Area_rule
> <https://en.wikipedia.org/wiki/Area_rule>
>
> Jet engine inlets are also sensitive to Mach angle, and must be designed with
> a chosen Mach number in mind, or must include variable geometry to control
> the shock position. The inlets of the F-111 and the XB-1 are good examples
> of this.
--
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