Nice and clear lesson. My only comment is that AR only affects the Cdi. The induced drag (in Newton) goes with 1/Span^2, and AR has no effect (apart from the applicability of the lifting line for low AR). AR can be misleading. Indeed, Di=(2/pi*rho)*(lift/(span*speed))^2
Thanks and interesting point! The aspect ratio being in the Cdi equation is really a fabric of the non-dimensionalization, and when re-dimensionalizing you get that the Drag is a function of span directly and the chord drops out of the equation. As a consequence, if you have a wing with a fixed span, you can't reduced induced drag by reducing the chord (though your overall drag will go down if my understanding is correct).
Hi Giju, you're welcome and I hope you enjoyed it! It is small, and a bit sloppy, but I think the intended direction of D_i is slightly downward (unless I'm missing something). This is the sketch around 5:44?
![Finite wing effects [Aerodynamics #15]](/img/logo.svg){kind=logo}
