Here is an excellent starting point to find all the software for the homebuilder of experimental and kitplane aircraft and helicopters. Let us know if you are aware of other we should add a link to. You can drop us a note here.

Aircraft Design

Aircraft Designs, Inc.

Airfoil Optimizer

Airplane PDQ

Desktop Aeronautics

Hanley Innovations

MathTools

Propeller Tip Speed Calculator

Public Domain Aeronautical Software

X-Plane  Read the Popular Science article about X-Plane.

Panel Design

Panel Planner

ePanelBuilder

Excel^® Spreadsheets

Note: the spreadsheets below were written by Neal Willford for EAA's Sport Aviation magazine and are for informational and educational purposes. Any aircraft design or modification done by an experimental aircraft or kitplane homebuilder should be thoroughly analyzed by an experienced aeronautical engineer.

Airloads - for Aircraft Under 6,000 lbs

Airloads - for Aircraft Under 6,000 lbs with Fabric Wings, Two Spars

S202-Design1math.xls

S202-Design1figs.xls

S203-Design2a.xls

S204-Design3f.xls

S308-Cooling.xls

S311-AC Design-Tails.xls

S312.xls

Liquid Cooling.xls

Other Software

Kitlog Pro Builder's Log Software