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tashley
12-10-2005, 03:18 AM
Here's a few shots of a test stand I built that I would like to share. The design concept is one that has been around for a while but I put this one together with my own personal changes and embelishments. I can set a motor up and get rpm, thrust, and of course all the electrical data my Wattsup will deliver.

Mike Parsons
12-10-2005, 03:59 AM
Nice and clean Tom.http://www.wattflyer.com/forums/images/icons/icon14.gif

Dr Kiwi
12-10-2005, 04:13 AM
Looks familiar.

tashley
12-10-2005, 04:57 AM
Thanks Mike. Dang Dr, I guess I'll have to put a little more shine on mine.:D

ragbag
12-10-2005, 10:33 AM
Here is my version of the test stand. It is the original, replaced the vertical arm so that I can test 14" props. Might have to get another scale. Pulled over five pounds with a MAS 13X8.5 the other day.

I can change the motor mount, which can be convenient. I have Axi motors and find it nice to be able to rearrange the mount.

If you should build one for yourself, be sure to clamp it to the work bench before putting the power to it.

By George

4529

tashley
12-10-2005, 12:32 PM
Nice. I have a number of motor mount adapters that I can slide in the vertical arm and lock down. Every time I test a motor with a mounting system different than those I have I make a new adapter.

Rugar
12-10-2005, 01:36 PM
Is there a formula for figuring out how long each arm should be? I may be wrong in my thinking, but if you were to lengthen or shorten each arm, would that not change the leverage point? Or do you all use the same measurements?

tashley
12-10-2005, 02:40 PM
Yes Rugar, good question. It does matter. The contact point for the scale and the mounting center for the motor should be of equal distance from the arm's pivot point. If those two measurements are the same it shouldn't matter how long the arms are just as long as you have enough tare adjustment to make up for the scale arm's weight.

Rugar
12-10-2005, 08:35 PM
Yes Rugar, good question. It does matter.
So your saying "Size does matter?" :D


The contact point for the scale and the mounting center for the motor should be of equal distance from the arm's pivot point. If those two measurements are the same it shouldn't matter how long the arms are just as long as you have enough tare adjustment to make up for the scale arm's weight.

Thanks for the response. I'm going to have to think about this. It just seems to me that even though both arms are the same length, different length arms (both being the same length) would affect the leverage point.
Example: Both arms being 10" long, verses both arms being 10' long.

tashley
12-10-2005, 08:46 PM
It dosen't matter. The only difference will be that the longer arms will put more pressure on the scale but all you have to do is set the tare on the scale at zero when the motor is in place and you've got it.

Rugar
12-10-2005, 09:05 PM
It dosen't matter. The only difference will be that the longer arms will put more pressure on the scale but all you have to do is set the tare on the scale at zero when the motor is in place and you've got it.

Thanks,
I may just have to build me one.

tashley
12-10-2005, 09:08 PM
It's one of those things that look pretty cool and you'll think you might use it but it may be hard to find the time to build.it Once you get it built however and put it in operation you wonder how you ever did without it.;)

ragbag
12-10-2005, 09:58 PM
Here is my version of the test stand. It is the original, replaced the vertical arm so that I can test 14" props. Might have to get another scale. Pulled over five pounds with a MAS 13X8.5 the other day.

I can change the motor mount, which can be convenient. I have Axi motors and find it nice to be able to rearrange the mount.

If you should build one for yourself, be sure to clamp it to the work bench before putting the power to it.

By George

4529

If you look at the picture of my thrust stand you will see the watt meter. You can test various props, rpm, watts, amps and thrust in grams or pounds.

The arm does make a differnce, that is why the rod from the stand to the scale is not fixed, it can be slid back and forth. Measure from the prop shaft to the rod. Move the block on the end of the rod to the center of the scale, measuring from the pivot rod on the vertical shaft.

Also I would use a metal rod only.

I don't mount my tach, the original plans show the tach mounted also.

For people who like stats.:D

By George

roccobro
12-10-2005, 10:08 PM
I modded my Glo-Bee tach to accept an external "eye" for the hard to reach areas, or where I was short a few hands. I used BEC plugs to make it removable, and just hot glue the remote eye where it is needed, and cover the internal one with some tape. It also keeps all my readout displays and controls in one spot.

Justin

tashley
12-10-2005, 11:33 PM
The point I was trying to make is that it dosen't matter how long the ninety degree opposed arms are as long as the distance is the same from the pivot point to the centerline of the prop shaft, and from the pivot point to the contact point on the thrust scale as I stated in post nr. eight. Just curious George, why would you use a metal arm only?

roccobro
12-11-2005, 12:20 AM
Just curious George

Me too. Get me in trouble with the man in the yellow hat sometimes. :)

Justin

ragbag
12-11-2005, 01:33 AM
I don't have to think about it breaking. The one unit looks like it has a dowl.
It also is easy to slide in and out to change the leverage. When I changed to the higher shaft to accomadate the 13.8 inch prop. I do have to keep an eye on it.

As I said I did pull over five pounds, that is all my scale will read, so don't know what I was actualy pulling.
Probably will never change back, as you said the leverage is the same as long as it is equal. Also the tare fine tunes it.

Monkey see, monkey do. ;) The first one that I saw was built with a rod. It was in a magazine a couple of years ago. Have the article in my file cabinet somewhere.

By George

tashley
12-11-2005, 01:36 AM
It's a hardened steel pin at the pivot point and the contact point at the scale is aluminum.

Dr Kiwi
12-11-2005, 05:01 AM
For those of you who don't visit RC Groups here is a link to "building a test stand":

http://www.rcgroups.com/forums/showthread.php?t=421578&highlight=thrust+stand+build

ragbag
12-11-2005, 11:17 AM
It is obvious that yours wasn't a dowl, Dr Kiwi's looked like a dowl.

After going over to RC Groups and looking at the thread it is a brass rod.

They say a picture is worth a thousand words, but not this time.

If some one made the same assumption that I did and had no way to see otherwise, by going to the thread, that could have gotten someone hurt.

I wear suspenders and a belt.

First time I've been to RC Groups in a long time, even longer for RC Universe.

By George