# Airplane Designer Software (Work in Progress)

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### Unknown_Target

##### Active Member
Hi everyone,

I'm learning Grasshopper for Rhino, it's a procedural modeling add-on (free!). As my first project, I'm developing an airplane design software for my model planes but I'm also setting it up to be useful for full-scale builders and designers as well.

Right now all I have is a single wing. I hope to add the ability for users to add weights, tails, multiple wings and more. You can check it out by clicking here.

Some feedback I need help with right away is: how can I account for wing sweep with total lift of a wing? I see "lift decreases by the cosine of the angle" but I don't know how to integrate that cosine into the lift equation. Any help would be appreciated - thank you!

#### pwood66889

##### Well-Known Member
"...account for wing sweep with total lift of a wing? I see "lift decreases by the cosine of the angle" but I don't know how to integrate that cosine into the lift equation..."
Hmmm... Lift equation I recall is the product of the area, the dynamic pressure (Rho*(velocity squared)) and a coefficient of lift that depends on the airfoil. There may be more wisdom out there on planform numbers.

#### Unknown_Target

##### Active Member
Yea I've got that in there, and the wing area changes with the angle - but as the wing sweep increases, I was reading that the angle of the lift vector changes due to the air hitting the profile from the side rather than directly on the front, leading to reduced lift overall. I'd like to integrate that into my simple lift equation.

So in case anyone's wondering how this works, you put in your desired stall speed and set your wing size. It will tell you how much lift the wing generates at stall. If it's more than your estimated weight then your wing is too small or stall speed is too low. Later I will add weight calculations and the ability to add multiple wings and CG/COL moments.

#### pwood66889

##### Well-Known Member
Agreed that the lift vector changes due to the air flow change in a 3-D wing. Fuselage pressure, etc., causes the flow to blow outboard on both wings, as visualized by "tuft testing." And it may be enhanced by sweeping the leading edge - one would have to do a full Finite Element Anal. to get it all. My question revolves around the amount of lift variance found in these factors. Would it be worth the effort/mips? And would setting wing size/stall speed too close make it flop one way or another due to a bug strike? Got some sumptuous beetles here in Florida...

#### Unknown_Target

##### Active Member
It doesn't look like there's an executable to download, it seems like I have to compile that software first.