To calculate which lifter was the most effecient, I needed a means of calculating the thrust that resulted from each input value. Using the cardboard protractor attached to my apparatus, I was able to measure the deflection of the lifter in degrees.

The force gravity exerts on the lifter downwards is 9.81 times the mass of the lifter in grams (f = mg). By weighing the lifters, I found that the small lifter weighed 6.25g, and the large lifter weighed 10g. Therefore, gravity is exerting a force of 61.3 mN [down] on the small lifter and a force of 98.1 mN [down] on the large lifter.

By noting the degree the lifter is deflecting, it is possible to tell what force the lifter is exerting against gravity. If the angle of deflection is 0°, the lifter is unable to overcome any of the force of gravity, and is exerting a force of 0. If the deflection is 90 °, the lifter is exerting a force equal to the force of gravity.

With this in mind, I developed the following equation to find the thrust of the lifters for each power input:

T = Fg ( sin θ )

Note: the thrust and the force of gravity are both measured in mN (micro-Newtons) because the mass of the lifters is quite small, and is measured in grams rather than in kilograms.

For calculating the efficiency of the lifters, I divided the output (thrust) by the input (power) for each power value and averaged these values for each lifter to obtain an average efficiency measure. The more efficient lifter will therefore produce more thrust for a given amount of power.