Re: Area Ruling?

On Feb 6, 9:56 pm, bbrought <bbrou...@xxxxxxxx> wrote:
On Feb 7, 7:05 am, "Ken S. Tucker" <dynam...@xxxxxxxxxxxx> wrote:

Years ago I built an F104 glider (without area ruling), it was
disappointing, so for the hell of it I area ruled it and it flew
much better. Subjectively, 30%+ more range, better stability
and magnificient stall qualities.
The 104 stall is fantastic. One wing (say left) goes first, and
it dips, then the a/c yaws left, then, due to the anhedral the
a/c rolls to the right to lift up the left wing, recovering the
left and stalling the right wing, so it oscillates then drops.
Ken

Oh for crying out loud - learn what technical terms mean before you
use them. Area ruling is about using an area distribution as close as
possible to a Sears-Haack body to limit wave drag. "Wave drag" - read
up what that is. Are you claiming your model was flying faster than
about Mach 0.6 to 0.8? If not, area ruling had nothing to do with it.
If anything improved in range it had to do with the reduction of other
forms of drag that have nothing to do with whether or not something is
area ruled.

That's what I now think too, that's why I think sub-sonic
"Viscosity Analysis" and Area Ruling are intimately linked.
It was repeated experimentation that upgraded the theory.

A bit of detail: the laminar airflow from the forward
part of the fuselage, (nose) goes over the surface,
call that Laminar Fuselage Flow.
It's sticky and produces a +p (positive pressure).
At the point LFF contacts Laminar Wing Flow we sum
the pressures, LFF(p) + LWF(p) to produce a
Laminar Mixed Flow, LMF(p) = LFF(p) + LWF(p)

Coarsely put, above the surface of laminar flow is the
Streamline Air Flow, (SAF). When the LMF mixes
with the SAF, turbulence and drag develope because
of mixing different air speeds.

By contouring the fuselage (pinch it), we design the
effect of LFF(p) = - LWF(p) , to aim for LMF(p)=0,
meaning the LMF has zero over pressure, and then
won't mix with the SAF.
Regards
Ken S. Tucker
.

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