Static longit stab: Think along the lines the effect that higher AR would have on Longit stab e.g. Cl-Alpha curve steeper
Directional Stability: Think along the lines of increased dihedral and increased effective AR would have, as well as any changes in roll and yaw inertia.
However, this question posed in the way it is, has certain traps...
What are we comparing with what ?
Are we comparing a pre-exisiting design without winglets with bolt on winglets?
Or are we comparing an aircraft using increased straight span with one using winglets to achieve the same effective induced drag reduction (with changes in profile drag being factored in, but incidental)?
A contemporary a/c design with winglets from the initial project definition stage would have other optimisations as well... e.g. it has been said that the only beneficial effect of winglets VS increased span per se, is that the wing-root bending moment is reduced offering a wing weight saving. Perhaps keep an eye out for this benefit (the Boeing Partners link above doesn't seem to even allude to it under 'benefits')
So, lay your terms of reference out clearly first, maybe even allude to the difficulty of comparing like with like (because they are not alike
), which should earn you a few brownie points!
I suppose the only obvious comparison today, is the more complex one, of an aircraft of identical aerodynamic performace garnered with and without winglets... raising plenty of questions, another of which is: would they have the same
effective dihedral?
Every decoding is another encoding
David Lodge