Wing drag minimization example problem

[Airbreathing]

Hi!
I have a question on the wing drag minimization example problem (https://github.com/peterdsharpe/AeroSandbox/blob/master/tutorial/02%20-%20Design%20Optimization/02%20-%20Wing%20Drag%20Minimization%2C%20with%20practical%20considerations.ipynb). I was wondering why the take-off speed is just an input and it is not allowed to vary? It could be set to 1.2*V_stall, where V_stall depends on the design variables aircraft weight and wing area.
I noticed they do a similar thing in the Master's thesis referenced here: https://github.com/peterdsharpe/AeroSandbox/blob/master/tutorial/02%20-%20Design%20Optimization/03%20-%20Aircraft%20Design%20-%20SimPleAC.ipynb. Should that take-off speed be regarded as a minimum velocity and be calculated based on the initial aircraft parameters? That could explain why it is set as an input and not allowed to vary.
Thank you in advance!

[peterdsharpe]

Hi there!

Great question! As you noted, the problem in the notebook was implemented following Berk's thesis. The original formulation I think goes back to Woody Hoburg's PhD thesis, available here!

In short, it's arbitrary - the minimum velocity could easily be allowed to vary, if that's of interest! Feel free to change it to a variable, set the appropriate constraints, and see how the design changes :)

[Airbreathing]

Got it! Thank you for your answer (and for your great work!) :)

[dangraf]

Hello!
I'm looking in to your fantastic library and have a pretty basic question since I have not studied aerodynamics in full.
This example of yours is very interesting for me (https://github.com/peterdsharpe/AeroSandbox/blob/master/tutorial/06%20-%20Aerodynamics/01%20-%20AeroSandbox%203D%20Aerodynamics%20Tools/01%20-%20Vortex%20Lattice%20Method.ipynb)
But where can I find the documentation of what the output of the simulation are?

D : 1.5500742218811423
Y : 7.706855400298031e-16
l : -2.839478665173283e-15
m : -2.255208490849847
n : 6.874722327848233e-16
CL : 0.7166310680840677
CD : 0.013849141449451634
CY : 6.8856916051199124e-18
Cl : -1.256025607871831e-17
Cm : -0.13339717342124371
....
I can guess some of them like Cl , D etc but is it possible to get a full list of all parameters and the units they are presented as in the documentation somewhere?

thanks!

[peterdsharpe]

Sure! They are here.

One particular note of caution is that Cl and CL are not the same in aerodynamics and flight dynamics - Cl is the rolling moment coefficient, and CL is the lift coefficient.

For more details on coordinate systems, conventions, and aerodynamics basics, I'd highly recommend Flight Vehicle Aerodynamics by Mark Drela.