Python method to find maximum I-beam

[TotallyPlaneCrazy]

Greetings, all

I am trying to code a Python script to find the largest and lightest possible I-beam to fit inside an airfoil, given a minimum Ixx requirement.

My method currently involves trying to fit the largest possible rectangle with all 4 vertices close to the airfoil coordinates within a tolerance, such that A(rectangle)/A(airfoil section) is maximum, A(rectangle)/Ixx(rectangle) is a minimum. So far I have generated some feasible options, but recently Python just complains that no valid solution is possible, despite CAD and my calculations proving the possibility

How would you approach this problem?

 

[rb1957]

forgive me, but I think your handle perfectly describes this idea !

The flanges of pretty much every spar I've seen conform to the OML of the wing ... ie a rectangular spar doesn't fit a wing ... unless you're in a very small plane (like a kit plane, where expense may be more important ... though I have experience with this too, and the spar flanges have been non-rectangular).

But if you do pursue this, remember the thickness of the web is another design constraint.

 

[GregLocock]

You'd need a lot more constraints to get a satisfactory answer. A simple optimiser will always maximise the height of the web and the width of the flanges, but the resulting I beam will be misproportioned and will fail in unusual ways.