Video 4 of 4. Test Number Three-3D Printed Hamilton Standard 11x6 propeller on thrust test stand.

This is the third thrust test of a new 3D printed propeller. This also is a completely new and untried model of the Hamilton Standard propeller. The airfoil is under-cambered with the scale outline of blades used on the Douglas A-20 Havoc. The scale is 1/12 with a diameter of 11.38 inches and a six inch pitch angle. The thrust test for this propeller was the most impressive of all four tests.

The thrust testing is the first stage toward testing these propellers in flight. A trainer plane will be used for the flight testing, one that was built for and flown with the motor/propeller combination used as a control in the first test. The same motor and speed controller will be used for all 3D printed propeller tests.

The measuring device for thrust is a School Supply Company Spring Scale, commonly known as a fish scale. The track is 8mm steel rod with the carriage mounted on four LM8UU linear bearings.
 
Here is a summary of all four tests:

Test Number-1, Master Airscrew 11x6 electric propeller.
Performance:
1/4 throttle, 4 ounces of thrust.
1/2 throttle, 9 ounces of thrust.
3/4 throttle, 22 ounces of thrust.
Full throttle, 42 ounces of thrust.

Test Number-2, Hamilton Standard 3-blade propeller, 1/12 scale, 11.38x6 for A-20 Havoc.
Semi-symmetrical airfoil.
Performance:
1/4 throttle, 4 ounces of thrust.
1/2 throttle, 8.5 ounces of thrust.
3/4 throttle, 19 ounces of thrust.
Full throttle, 39 ounces of thrust.

Test Number-3, Hamilton Standard 3-blade propeller, 11.87x4 for Tower Hobbies F6F Hellcat.
Under-cambered airfoil.
Performance:
1/4 throttle, 6 ounces of thrust.
1/2 throttle, 14 ounces of thrust.
3/4 throttle, 21 ounces of thrust.
Full throttle, -------------Null------------.

Test Number-4, Hamilton Standard 3-blade propeller, 1/12 scale, 11.38x6 for A-20 Havoc.
Under-cambered airfoil.
Performance:
1/4 throttle, 8 ounces of thrust.
1/2 throttle, 21 ounces of thrust.
3/4 throttle, 32 ounces of thrust.
Full throttle, 49 ounces of thrust.