Motor Test Stand – What’s my thrust?

My latest project is a motor test stand inspired by an old Flite Test video. The idea is to try out different motors and props and directly measure their thrust and amp draw.

It’s form is an Isosceles triangle. The idea is that thrust is applied by the motor at the top left corner (B), and is transferred to a digital scale which sits under the bottom right corner (C). The frame is hinged at the remaining corner (A), directly beneath the motor, allowing the frame to rotate and apply pressure to the scale. The horizontal arm (AC) and the vertical arm (AB) are the exact same length.

diag

Here’s the finished frame, made from basswood, balsa, a Popsicle stick and some bamboo skewers. The long arms are 18″ each; I cut a single piece of 1/2″x1/2″x36″ balsa in half at a 45 degree angle and glued it back together to form the right angle of the frame.
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The thrust is directed onto the scale via this short length of bamboo skewer.
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The third corner is attached to the frame’s “foot” via a small hinge.IMG_1529

Another view of the hinge.
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The motor(s) mount to a stick mount at the top corner of the frame. The ESC and other components are held in place with zip ties.
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Here’s the full setup. 1-Motor; 2-Peg for motor mount; 3-ESC; 4-LiPo; 5-Watt meter; 6-Digital Scale; 7-Rx.

1-Motor; 2-Peg for motor mount; 3-ESC; 4-LiPo; 5-Watt meter; 6-Digital Scale; 7-Rx

1-Motor; 2-Peg for motor mount; 3-ESC; 4-LiPo; 5-Watt meter; 6-Digital Scale; 7-Rx

My first measurement: AX-2308N-1100 with an EP-9050 prop on an 850mAh 3-cell: 20+ ounces at 9.7 Amps.

Here’s my first actual use of the stand, looking at different motors and props for my SkyBuggy build:

Data table from propeller tests

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