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Old Apr 06, 2005, 09:04 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,439 Posts
Blade Runner N20 Tests

Allan Wright of Wright Brothers RC is now selling Blade Runner replacement parts. Allan gave me a couple of motors and I naturally ran the standard motor tests on them. Here's a table with the results, including the N20-LV from All Electronics and also the M20-LV for comparision.

The N20-LV is really more of a MV (medium volt) motor. This is why in Jochen Bergmeyer's Feb 2003 Inside Story article he tests this motor and concludes it is happiest at about 5.5V and runs his with a voltage booster. The hotter wind, and lighter, M20-LV has always been a better 1-cell (LiPoly) motor.

With the N20-BR (Blade Runner) it looks like we have a true 1-cell N20 motor. The motor also has strong magnets and cogging that you can feel when turning the motor. Stronger magnets will make the motor develop its power at a lower rpm.

From the table below we can see that the N20-BR develops 1.69 watts of output power at max power rpm. This is 55% more than the N20-LV and nearly 10% more than the M20-LV. In addition, the max power rpm of 10,900 is lower than the N20-LV's 12,300, and much lower than the 23,400 of the M20-LV. This means the N20-BR should do quite well as a DD motor and should be able to swing a larger prop than either of the other motors. Amp draw of 1.04 is higher than the N20-LV, and about the same as the M20-LV, but is still within what a Kokam 145 can handle.

Properly geared the N20-BR may be the solution for planes with geared N20-LV's that need a bit more power. Compared to the M20-LV only about 10% more power is obtained, so a geared N20-BR does not offer as much advantage. The N20-BR is, however, slightly more efficient than the M20-LV.

Gordon
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Last edited by Gordon Johnson; Apr 07, 2005 at 07:40 AM.
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Old Apr 06, 2005, 10:00 AM
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Dave Wulff's Avatar
USA, FL, Fort Lauderdale
Joined Feb 2002
1,902 Posts
Gordon,

Interesting results, thanks for taking the time. I like the idea of the DD setup for something like the Bump, just ordered some from Allan. On most of these types of motors, availability long term will be a problem, best to stock up on a few when they are available.

Dave
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Old Apr 06, 2005, 10:08 AM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
5,192 Posts
I will have these motors on my website for sale on Monday. I'm just finishing up filling my backorders this week. I wanted to give those people on my waiting list a few days to get their payments in to insure they got first shot at these motors.

Once I gauge interest from the non Bladerunner community I'll try to arrange to have a more steady supply of these motors.

Thanks for doing the motor tests Gordon!

Allan
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Old Apr 06, 2005, 10:09 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,439 Posts
Allan,
No problem.

Dave,
I'll try and find time to do some static tests to find a good prop for the motor DD. I think it should be able to pull a larger prop than the U80 or GWS 4x2.5. But, I'm not sure what that prop will turn out to be. It might have to be a larger prop trimmed down, in which case I'll probably leave that to others to figure out.

Yup, it's often good to stock up. I'm glad I've got several M20-MV's hoarded since we now know that motor source has dried up.

Gordon
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Old Apr 06, 2005, 10:42 AM
Gravity is a harsh mistress.
Tim Wolff's Avatar
United States, MI, Temperance
Joined Sep 2002
6,611 Posts
Thanks for the data Gordon!!

I stocked up the first time Allan offered these motors. For anyone that has not followed the massive BR threads the following bears repeating:

For longevity, the GWS N20 carbon brush endbell can be swapped onto the BR motors. In cases of the comm in the BR motor already worn/burnt/ruined, the comm and endbell from the GWS N20 can be swapped in. Don't toss those cooked BR motors!
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Old Apr 06, 2005, 11:03 AM
Heli Bouncer
Looooeeee!'s Avatar
At the Discount Clambake
Joined Feb 2001
3,932 Posts
Hi Gordon,

Is there a chance you could test the GWS 4.8 v B2c motor also? I've got a few. I'm curious about their worth at single cell Lipoly voltage levels.

If you can of course,

Thanks

Lewis
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Old Apr 06, 2005, 12:10 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,439 Posts
Sorry,
I don't have any of those GWS N20's.

Gordon
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Old Apr 07, 2005, 12:56 AM
Registered User
Oslo, Norway
Joined Nov 2003
344 Posts
Gordon

Nice, thank you for doing the tests.
In a helicopter with low rotor rpm (like the Bladerunner) it is critical to have as low motor rpm as possible to reduce the loss in the gears and at the same time keep a high efficiency at max power output.

Hopefully, ITC will be able to support the motor for some time. As long as we use it in the BR the motor factory will run production batches, but I am not sure if they will keep up the production if the BR changes motors. (however, it looks like we will use the same motor for this years production)

Petter
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Old Apr 07, 2005, 04:07 AM
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billsmithjr's Avatar
Amishtown, Maryland
Joined Sep 2003
795 Posts
I can confirm the the n20br works well as a one cell motor . I don't know about a direct drive prop but I can tell you it works great with the DJ arrow tec gears and a gws 6050 prop that I cut a quarter inch from each tip. Hauls my 24 inch blue core cessna nicely.
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Last edited by billsmithjr; Apr 07, 2005 at 04:12 AM.
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Old Apr 07, 2005, 08:04 AM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,439 Posts
Petter,
The fact that the N20-BL motors perform so well on one cell, and their low-rpm nature, just confirms once again why the Blade Runner is such a successful product. You sweat the details to make sure the BR had the "right" motor, not just any motor.

Gordon
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Old Apr 11, 2005, 02:09 AM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
5,192 Posts
Motors are available for sale through my website for US customers. Hopefully once I catch up with those orders I'll still have enough motors to offer them to international customers.
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