SUBSIM Radio Room Forums - View Single Post - Flight models: MS-FSX vs X-Plane 9

Lieste · 08-13-09, 06:54 AM

There is only a linear interpolation of lift between the (adjusted by gross wing characteristics eg Aspect Ratio) section data for root and tip.

The root and tip elements of a non-twisted, non-tapered rectangular wing have equal lifts in X-plane. The real airflows have (approximately) elliptical lifts regardless of planform (the deviation is ~20% for a typical wing, which is far from the assumed linear distribution of lift).

NASA have far more advanced forms for determining lift distributions, and I have used these in the past to approximate the lift distributions over a wing/tail combination. The feel resulting is very different from the #generalised# raw data used within the same flight-model, even when total lift and drag are the same.

08-13-09, 06:54 AM	#15
Lieste Soundman Join Date: Oct 2008 Posts: 142 Downloads: 0 Uploads: 0	There is only a linear interpolation of lift between the (adjusted by gross wing characteristics eg Aspect Ratio) section data for root and tip. The root and tip elements of a non-twisted, non-tapered rectangular wing have equal lifts in X-plane. The real airflows have (approximately) elliptical lifts regardless of planform (the deviation is ~20% for a typical wing, which is far from the assumed linear distribution of lift). NASA have far more advanced forms for determining lift distributions, and I have used these in the past to approximate the lift distributions over a wing/tail combination. The feel resulting is very different from the #generalised# raw data used within the same flight-model, even when total lift and drag are the same.