[Crumpp]

The difference between mine and your approach is that I calculate the changed induced drag due to weight change (which means that Cl/AoA change is accounted) while the formula you use, assumes constant Cl/AoA which is a wrong approach for this particular case.

Harry PHil,

I am very familiar with "your technique" btw. It's not new or original. In fact I use it in a spreadsheet I constructed to predict aircraft performance. I would be glad to share that spreadsheet with you.

However you still have to go back and couple the affects of the power reduction. Only this time we have to do it manually. The end results are exactly the same.

The standard BGS formulation presented in numerous aerodynamic and engineering text I posted in this thread works just fine at illustrating the affects of weight. The end results are exactly the same.

An increase in weight represents a significant reduction in performance.

All the best,

Crumpp