Originally Posted by hawk37
Re point 2, just to make sure I understand what you've written, is it correct to say then that an aircraft straight and level, with the 2 different configurations I gave in examples 1 and 2, and both at 5 degrees pitch, will therefore be considered to be at the same aoa?
At an
aircraft level, yes, they have the same AoA - the data that goes into any kind of 6dof model, such as a flight simulator, won't muck about trying to adjust chordlines and such.
Now, if I'm doing detailed fluid-dynamics design work and endeavouring to, say, tailor the natural stall breakdown across the wing then consideration of local flow angles is important, but you have to really get into the weeds for that to matter, and nowadays it'd be done by 3d CFD, again using the aircraft-level AoA rather than worrying about the local conditions
To address J_T's points: yes, OEMs all use much the same definitions for Sref, so you can ROUGHLY compare CL-max across products. But I've been involved in some significant wing changes which added wing area where we chose not to change Sref (or the MAC definition) to keep data comparisons simple. Now, anyone marvelling at how we increased CLmax by 10% without spotting we had increased the area by 5% would be misled, but since as J_T also says no-one outside of the CFD bragging-rights wing design community gives two cents who has the "highest CL" it doesnt matter.
And if you think Sref is subject to a bit of creative accounting, just try to compare fin areas ....