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Old Feb 08, 2013, 08:20 AM
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Super Simple Test Bench for motors and props


I wanted to test a motor and a prop quickly and easily.
That's why I have done this super simple test bench.

There are better designs and constructions, but this one works perfectly and is light, strong, cheap, quickly made, convenient to use and easy to store.

Needed:
Three pieces of wood (100x60x20mm in my case), only 7 holes to drill,
4 woodscrews, two 3mm screws for the motor, single sided adhesive foam tape,
Turnigy Servo Tester, Wattmeter, ESC, battery and scale.

Demonstration:
Turnigy Park480 850KV, 3S 3300mAh battery and 5kg scale,
4 props: APC 10x4.7 SF, GF 10x4.5, Graupner 10x5 and Graupner 11x5.
2 levels: half throttle (1.5ms pulse width), generally used to hover, and full throttle (2ms) for max thrust.
Half throttle thrust and efficiency are the most interesting values for multicopters.
Tare is automatically done when switching on scale.
Props are positioned upside down on motor.

APC 10x4.7 SF
50%: 12V, 4.4A, 53W, thrust 444g, efficiency 8.4g/W
100%: 11.6V, 18.4A, 213.9W, thrust 1134g, efficiency 5.3g/W

GF 10x4.5
50%: 12.2V, 4.4A, 53.5W, thrust 433g, efficiency 8.1g/W
100%: 11.8V, 17.8A, 210.3W, thrust 1141g, efficiency 5.4g/W

Graupner 10x5
50%: 12.1V, 3.7A, 45.2W, thrust 381g, efficiency 8.4g/W
100%: 11.9V, 12A, 142.5W, thrust 885g, efficiency 6.2g/W

Graupner 11x5
50%: 12.3V, 4.2A, 51.8W, thrust 456g, efficiency 8.8g/W
100%: 11.9V, 15.5A, 183.9W, thrust 1189g, efficiency 6.5g/W

Among the 4 props tested with this motor at this voltage, Graupner 11x5 is the best, APC and GF being not far behind.
These combos are suitable for 1400-1600g quad, 2100-2400g hexa or 2800-3200g octo.
That's what I wanted to know.

This simple test bench might help you choose motors and props or solve problems.
Any improvement suggestion would be appreciated.



Last edited by Mortimer; Feb 09, 2013 at 11:30 AM. Reason: Added Graupner 11x5
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Old Feb 09, 2013, 10:57 AM
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Graupner 11x5 has been added to the previous test.

Park480 850KV and Graupner 11x5:
50%: 12.3V, 4.2A, 51.8W, thrust 456g, efficiency 8.8g/W
100%: 11.9V, 15.5A, 183.9W, thrust 1189g, efficiency 6.5g/W
Old Feb 10, 2013, 04:00 AM
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Could be simple but not relevant results, too close to the bench.

My take about really useful and simple has been posted here:
https://www.rcgroups.com/forums/show...&postcount=261
Old Feb 10, 2013, 04:41 PM
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I have used for more than one year a conventional test bench with a vertical propeller.
Advantage: absence of ground effect.
Drawback: volume of the device and horizontal air flow, everything is blown away on a two meters distance.

Super Simple Test Bench has none of these disadvantages.
It's small, air flow is vertical and air speed below the prop is insignificant.
That means it can be used instantly on your desk surrounded by sheets of paper, nothing fly around it.
There is also no ground effect, ceiling being 2 meters above the prop, and no drag due to arm supporting the motor.

Values recorded with the two devices are practically the same.
Build one, it's easy, you will compare with what you have got before.

Old Feb 10, 2013, 06:06 PM
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I like it!

I'm gonna have to try this. I just bought this wattmeter for testing.
Old Feb 10, 2013, 06:32 PM
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Nice ! When it will be working, give us your impressions.
Leave some distance between prop and table, at least 13-15cm.

@ renatoa

I have also made the test bench below.
I have been disappointed, not accurate enough.
Last edited by Mortimer; Feb 10, 2013 at 07:04 PM.
Old Feb 11, 2013, 01:20 AM
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Which way not accurate? compared to what ?
For me it seems to describe very well the horizontal thrust in a real plane.
Conversely, the bellcrank direction change mechanism is the one not inspiring confidence to me.


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