Rob, et al.

The early 235 (and the likewise, early 235's that were converted to 320's - a la Don Goetz's test mule) did have the fuselage fairings lined up with the flaps when the flaps were at "neutral". I've been flying 235 hull number 50 since '93 and have always wished it wasn't so since I'm sure the gap produces some un-needed turbulence/drag. I have often thought of installing an end-plate on the bottom of the inboard end of the flap that would partially close off the mis-match when in reflex, but have never followed through. (Flying season here in the inland Northwest is just too short to have the airplane AOG while fiddling with something that may not do anything positive).

The NLF series are good low-drag airfoils that maintain laminar flow over a good range of conditions, but like everything else in aircraft design you don't get something for nothing, and the NLF-0215 does have quite a relatively high pitching moment. This creates two problems (both more or less proportional to airspeed): high torsional stress in the wing structure, and to maintain level flight, high trim-drag due to countering the nose-down force with the elevator.

Reflexing the relatively long flaps alleviates the high pitching moment over a good bit of the wing span and is why, on the early 235's at least, reflex is required (according to the factory back in the early '90's) at and above 160 IAS (MPH). Fortunately, doing what is required for structural reasons also makes the airplane go fast by reducing the otherwise high trim-drag.

Dan Schaefer
Early 235   N235SP --
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