Low Speed Airfoil Design

Joan Puig

Project Goals

● Maximize L/D● Easy to build● Keep Cm at a value that is not going to make the

airplane unstable● Have space for a strong structure● Design an optimal airfoil for my RC airplane

Tools

● Panel Method to generate Cp distribution● Shape adjusting function● Optimizer● Drag estimation tools (future work...)

Shape Adjusting Function

● It generates any reasonable airfoil starting from a guess and a set of linerly independent bump functions.

Bad bump function choice

Optimization Process Review

● Don't assume anything about the input data● Fit the input data using a spline to the desired X

coordinate values● Pass appropriate parameters to the optimization

function● Collect data periodically

Guess

20 Iterations

40 Iterations

60 Iterations

Final Result

Convergence rate

Speed

● Solving a matrix is o(n^3) -> most of the time is spent here

● Try to be able to fit your matrix in the cache– 32*(n^2+8n)/(8*1024)<available cache ~128-512

● Don't calculate x^2, x^3, sin(...) exp(...^n)... every time, compute them at the beginning and use them as global variables