Very Simple Motor Test Bench - RC Groups
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Apr 18, 2011, 10:32 AM
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Very Simple Motor Test Bench

Hi guys,

I have come up with a very simple design for testing motor thrust and I would like to know your opinions.

The idea is to have two scales with a heavy weight connected with an square tube and place the motor in the middle. When the motor is on, the weight that will be substraed from both scales will be the real thrust.

I attach a picture of the design.


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Apr 18, 2011, 10:45 AM
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Intersting concept, I think it would work. However, the ones I have seen Dr. Kiwi et al use are pretty simple and require only one scale and less math. Check them out, they are probably about as simple as it gets.
Apr 18, 2011, 10:54 AM
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Ken Myers's Avatar
Originally Posted by ivgarcia
Hi guys,

I have come up with a very simple design for testing motor thrust and I would like to know your opinions.
Simply put:
Motors create torque. Props create thrust.
Apr 18, 2011, 11:14 AM
Suspended Account
In fact there is no axis, so...

You might have a part of the weight you are measuring that in fact comes from the torque, in a way that you can hardly know.

Vibrations might cause mistakes too...

So it may not be very close to reality, but it might be enough.
Apr 18, 2011, 12:33 PM
Registered User
Dr Kiwi's Avatar
Concept is okay...pusher configuration (pushing down on the scales) would obviate the need for math.

One serious issue is the fact that you are standing in the way of a dangerous object (the prop) spinning horizontally at high rpm.... if a blade lets go, it will scythe its way at you or someone else... that why I moved on from my original "vertical thrust" stand, to a far safer "horizontal thrust" stand, so that I can be safely behind the prop when it is spinning, not directly in its path.
Jun 06, 2011, 02:05 AM
KG7TTQ - Las Vegas
mark_q's Avatar
Here is my latest (this is gen 3). It's a pusher type, was easy and cheap to build and does a very consistent job for motors of up to 2000 watts and prop thrust measures up to 176 oz. It's also safe as I run it remotely.
Happy Testing! - Mark
Jun 06, 2011, 01:04 PM
just look at it smokin'
z-matrix's Avatar
i use a frame on top of the scale, EDF upside down, zero scale, then start testing.
What is your opinion simple enough?
Oct 10, 2011, 05:42 PM
We can rebuild it!
djdavies83's Avatar
I'm going to subscribe to this, I'm really curious about how much thrust comes out of these coaxial toy helicopters, other than what seams to be the standard method of securing the heli to a weight on the scales and then working out weight difference with the throttle up, any ideas on how I could get it more accurate?

I think the method I mentioned would be inaccurate as with the heli so colse to the ground it would give a higher reading by pushing against the ground.
Oct 10, 2011, 06:17 PM
Registered User
Dr Kiwi's Avatar
Hey Mark,

If I am seeing it correctly... in your "set up for a test photo" you need to reverse the prop (convex face facing the motor) to get the pusher effect. As it is, with the motor running in reverse as it needs to be, you are using the "back" of the prop to push air.

That is a nice solid set-up you have made... mine is probably limited to 2kg thrust.

Cheers, Phil

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