AutoSpeed, an Australian website, is running an article on how to measure drag and lift without a wind tunnel. The article notes:
At higher speeds, the power developed by the engine is used almost entirely to overcome aerodynamic drag. If engine power is then measured in different aerodynamic configurations, changes to drag can be seen.
An indication of the amount of engine power required to overcome drag can be found by measuring the engine’s air consumption at a constant speed on a level surface. This can most easily be carried out by measuring the airflow meter output voltage or frequency by means of a multimeter mounted in the cabin. (Note that while it may at first appear that a more accurate result would be gained from measuring injector duty cycle, in practice this figure jumps around a lot, even at a constant speed!)
