My goodness... phew...
If we're sticking to the original question, I think
ahramin had it best covered quite a while back.. my answer would be much the same as his. The Slow and heavy bit is easy of course, vorticity function of Cl ^2
Somebody said this of those authors quoting also CLEAN as a condition..
Perhaps the authors of 90-23F know something that aerodynamicists don’t. Aerodynamicists would be willing to accept the knew knowledge if only the authors would divulge what it is.
This is matter of QUALITY Vs QUANTITY as
ahramin said I think...
Due to non-elliptic distribution, the TOTAL vorticity will almost certianly be highest with flaps extended (perhaps even with Fowlers extending without deflection, which also upsets the elliptical distribution)
BUT, that DIRTY voriticity will not all be wound up fractionally inboard of the wingtip, as it would for a nominally elliptical distribution*
So the upset(ting) potential may well be less, when in a dirty configuration, with strong trailing vortices but several of them across the span, dumping at points where there are significant steps in chordwise circulation (which is what creates lift).
* A straight taper wing of sensible (>7) AR and of nominally constant section and a wee bit of washout, does as someone stated, produce a spanwise lift-distribution quite close to elliptical, maybe close to 0.9 efficiency factor.
-
The Spitfire Wing -
The story goes that this was
not made elliptical due to the so-called 'ideal' lift distribution (an expensive production challenge anyway, as Vickers found out). It was originally
sketched by RJ Mitchell, around the constraints he had to work with...
Span
Area
Thickness (Spit was always a thin wing, )
Guns- 8 of them within the above three constraints...meant that he had to keep the chord wide well outboard
The
consequence was that he opted for a nominally elliptical planform to fit everything in, was accused of copying the Heinkel He70, certainly admired its aerodynamic smoothness, but his colleagues denied it had significantly influenced the Spitfire's layout.
Physical constraints had determined the Spirfire's wing (Mitchell was known as a good down to earth practical, not a fanciful or too theoretical engineer). Of course, he was aware that this planform wouldn't do any harm to it's maneouvring drag and so it also proved, whatever came near or bettered it at various stages in it's fighting life, it always could turn inside them, and at a similar power output, outclimb them in steady state (non-zoom) conditions.
Even the last of the line, the Griffon powered Seafires could climb to 40,000 feet faster than almost anything piston powered, certainly getting up there quicker than a Sea Fury (10 minutes from memory). In fact it could go on to about 50,000 & 51,500 wasn't unknown in the tropics! That was 10 years after it first flew too...quite a sustained development programme that
that original elliptical wing (strengthened immensely torsional stiffness) made possible. The main spar was an absolutely unique design... (thin wing, had to be a bit special)
Thus, however highly thelater P51 is rated, the Spit was always to its last operational days, the better pure interceptor, exactly what it had been designed to do in 1935/6... and the 'accident' of the elliptical wing may have helped a bit.
Oops! Have I strayed somewhat
