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MicroDAN 2505-2900Kv Delta/Flying Wing Outrunner Motor Review

A handbuilt, hand-machined masterpiece of a motor puts a fabulous flying wing from an RCGroups.com vendor through the wringer.

Splash

Introduction

MicroDAN 2505-2900Kv Delta/Flying Wing Outrunner Motor
Weight with Motor Mount:1.26 oz (36g)
Number of Turns per Pole:10
Wire:23 AWG
Number of Magnets:10
Average Operating Voltage:10V
Maximum Current Draw:38A
No-Load RPM:29,300 RPM
Kv Rating (RPM per volt):2900Kv
Shaft Diameter:3mm
Manufacturer/Distributor:GoBrushless.com, 611 Evan Edwards Road, Ellenboro, North Carolina 28040 USA
Price(USD):$54.99

There's an intrinsic value to a fine, handmade item. From art to automobiles, quality handmade goods command a premium price.

When handbuilt quality combines with a reasonable price, the result is very much like the subject of this review.

The MicroDAN 2505-2900Kv ten-pole delta wing outrunner in this review was specially built for the review of the Foam-Tec Wingthing2 flying wing, sold here through RCGroups.com by Foam-Tec in Puyallup, Washington USA.

During the course of our correspondence, Foam-Tec's Dan Burdick recommended the use of this fine motor to move the Wingthing2 at speeds approaching 100 MPH (160km/h).

That in turn led me to its creator, Daniel Sny of GoBrushless.com in Ellenboro, North Carolina USA. Daniel builds each and every MicroDAN motor from the ground up, with the only commercially available parts used in the build are the stator, magnets, bearings and some odd bits of hardware. The beautifully crafted endbell and mount are machined by Daniel himself while each stator is hand-wound. All MicroDAN motors carry a lifetime warranty against manufacturer defects. If one's motor does in fact fail, it's a simple matter of emailing the company for return instructions.

This particular creation is capable of swinging APC props ranging from 4.7x4.25 to 6x4 with either a three- or four-cell li-po.

If a custom wind is required for a specific project, no problem.

So impressed was I with the work and the care that went into this motor that I wanted to showcase it in its own review.

For those who are ready to step up to a motor which will push a delta or flying wing to some truly breakneck speeds, this motor might well be the ticket. It certainly was for me.

Contents

Inside the hand printed box is a hand printed bag. Ah, but inside said bag is that marvelous motor and a Motrolfly propeller collet. That was a rather pleasant surprise; I've had a lot of terrific dealings with Ken Young of Subsonic Planes, the North American distributor for Motrolfly products. Mounting screws are also provided.

As far as the motor itself was concerned, I simply wasn't expecting anything this nice looking.

Here was a motor which Daniel built specifically for this review and it was a beauty with its brushed finish and asymmetrical cooling vents. Only the hand-engraved ID marking atop the endbell belied its handbuilt status.

Other than an airframe, the only things required are:

  • Bullet connectors
  • 40-amp ESC
  • APC propeller from 4.7x4.25 to 6x4

Kevin and Andria Henrie of RCPlaneBuilder.com in Lake Point, Utah sent over a Suppo SP-40A 40-amp ESC and a pair of their own Pro-PACKS 1050mAh 3S 35C li-pos complete with preinstalled Deans-compatible connectors and a charge rate of up to 5C for use in the review of the Wingthing2. They were recommended to me by Dan Burdick, creator of the Wingthing2. After dealing with them myself, I can cheerfully recommend them as well. Great prices, great products, great people.

Now that I've had a chance to fly the wing, I can say the Suppo ESC is a terrific match for the motor at an almost ridiculously low price of US$17.95 through RCPlaneBuilder.com.

Installation

In this particular instance, installation was a simple as drawing crosshairs on the Wingthing2's motor box in order to accurately center and install the mount. The motor is then simply bolted back onto the mount with a 1.5mm hex head driver.

I originally attached the mount with the setscrews on a horizontal plane, making it difficult to attach the motor. Rotating it 90 degrees to put the setscrews on a vertical plane made it far easier to attach the motor and will make future removal a lot easier.

Once the wing was completed and test flown, I gathered some real world performance numbers with an Astro Flight Super Whatt Meter and a Hobbico Optical Mini-Tach. The propeller was an APC 5.5x4.5 Speed 400 standard rotation propeller as recommended by Dan Burdick. The prop was installed with the ID numbers forward and with the motor rotating in a standard counterclockwise direction when viewed from the front.

Although I haven't tried it as of this writing, Dan claims additional torque and a slightly higher top speed if the propeller is installed with the numbers facing rearward. I'll have to try that and comment on it later.

The battery was one of those provided by RCPlaneBuilder.com and the numbers are pretty much what the manufacturer claims:

Battery Charge at Start of Test:12.60V
Current Draw at Full Throttle:31A @ .071 watt-hours
Battery Voltage During Test:10.35V
Propeller Speed:20,730 RPM

And oh, what a glorious sound it makes. Unfortunately, the wind noise in the video drowned out most of it, so the sound is muted beneath the music.

Flying

Since I've already covered the flight characteristics of the Wingthing2 in that model's review, I'll keep it brief:

This motor moves.

It had no problems whatsoever moving the wing at some very heady speeds, but it's a power-hungry little monster.

This isn't surprising given the prop speed, model speed and battery capacity, but one would be well advised to set the timer on the transmitter for no more than three or four minutes.

I found this out the hard way when I was bringing the model around to final after the power started dropping off. The motor cutoff kicked in, sending the wing on a graceful glide right into a small tree.

No serious damage to the wing or to my ego.

Flight Video/Photo Gallery

Conclusion

If my example is any indication, the entire line of MicroDAN motors may well be the Swiss watches of the R/C world. In my opinion, they have a look and feel that mass production simply cannot duplicate at a price which belies the work that goes into them.

When one considers the price, performance and lifetime warranty against manufacturer defects, I can give no less than two thumbs way up. It's an absolutely beautiful piece of work and one I highly recommend for anyone looking for a pusher prop outrunner.

Huge thanks go to Daniel Sny of GoBrushless.com for generously supplying this magnificent motor for use in the Wingthing2 review. Dan Burdick deserves a truckload of thanks for providing a sample of his Wingthing2. Dan is an RCGroups.com supporter and has been putting model airplanes in the air since 1960. The Wingthing2 may be ordered through his RCGroups.com page found here.

Kevin and Andria Hendrie of RCPlaneBuilder.com were a delight to work with and I hope to do so again soon. Their customer service alone makes them worthy of consideration. Kudos galore for the Suppo ESC, the Pro-PACKS batteries...and even some Tootsie Rolls!

If ever there were a go-to guy for reviews such as these, it's Mike Greenshields of Global Hobby Distributors. Mike not only provided the Airtronics receiver but some terrific new metal geared digital servos under the Hobby People brand.

Angela Haglund is the RCGroups.com administrator who makes all of these reviews possible for you, our thousands of readers worldwide.

Thanks for swinging by and enjoy your stay at RCGroups.com!

Pluses and minuses

Lots of pluses here, including:

  • Extremely high quality machining and construction
  • Lifetime warranty against manufacturer defects
  • Terrific performance
  • Great price, especially given the level of handcrafting
  • Among the finest motors on the market today

No minuses were noted.

Last edited by DismayingObservation; Mar 20, 2013 at 11:01 PM..

Discussion

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Old Mar 24, 2013, 11:31 AM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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You really need better batteries.. if you are down to 10.35v under load (3.45v/cell) so you are at the risk of LVC cut-off from the get go.... unless you are setting LVC well below the typical, and safer for your pack, 3.5v/cell.

I can't understand Dan's backward prop idea.. that would be hopelessly inefficient.

Conventional wisdom would indicate that your 5.5x4.5 prop is close to the limit for the motor ... one generally tries to use a prop which allows the motor to spin at at least 70%-75% of Kv x V... in your case 20730 divided by 10.35 x 2900 is only 69%..... so a 6x4 would be far too much.

Could you, please, explain "31A @ 0.071 watt-hours".... I can see 31A @ 10.35v = ~320watts.

I am interested that the performance of this 10-pole 2900Kv motor is pretty darned close to that of the 14-pole 2505 Speed motor (~2810Kv) which I tested for Dan some years ago (2007):

5.5x4.5 APC E: 11.1v, 32.30A, 354W, 21690rpm, 92.4mph, 758g, 26.69oz, 2.14g/W, RPM as % of Kv x V = 69.5%
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Old Mar 24, 2013, 12:05 PM
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Southern California
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Quote:
Originally Posted by Dr Kiwi View Post
You really need better batteries.. if you are down to 10.35v under load (3.45v/cell) so you are at the risk of LVC cut-off from the get go.... unless you are setting LVC well below the typical, and safer for your pack, 3.5v/cell.

I can't understand Dan's backward prop idea.. that would be hopelessly inefficient.

Conventional wisdom would indicate that your 5.5x4.5 prop is close to the limit for the motor ... one generally tries to use a prop which allows the motor to spin at at least 70%-75% of Kv x V... in your case 20730 divided by 10.35 x 2900 is only 69%..... so a 6x4 would be far too much.

Could you, please, explain "31A @ 0.071 watt-hours".... I can see 31A @ 10.35v = ~320watts.

I am interested that the performance of this 10-pole 2900Kv motor is pretty darned close to that of the 14-pole 2505 Speed motor (~2810Kv) which I tested for Dan some years ago (2007):

5.5x4.5 APC E: 11.1v, 32.30A, 354W, 21690rpm, 92.4mph, 758g, 26.69oz, 2.14g/W, RPM as % of Kv x V = 69.5%
Hello!

I used the batteries recommended to me by the model builder, so I went with his recommendations. This was a bench test with the motor at full throttle on a battery with two flights to its credit...but going nowhere. I was a bit concerned about the drop as well, but the LVC has yet to kick in during flight. I'm chalking it up to the extra work the motor had to do by trying to move an immovable model.

The prop was the one recommended as well; I was a bit surprised at the suggestion of a conventional prop versus a pusher. I have yet to try the reversed prop idea, so for now, it's spinning the usual counterclockwise/numbers front when viewed from the front.

Regarding the power draw, the Whatt Meter simply showed a current draw of 31 amps and a watt-hour reading of .071.
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Old Mar 24, 2013, 09:16 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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Regarding the power draw, the Whatt Meter simply showed a current draw of 31 amps and a watt-hour reading of .071.

My math might be fuzzy, but 0.071W-hr suggests that you must have only run the motor for about 1.25 seconds (Power input of 320W for ~1.25 seconds equates to 0.071W-hr worth of power)
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Old Mar 24, 2013, 10:34 PM
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Quote:
Originally Posted by Dr Kiwi View Post
Regarding the power draw, the Whatt Meter simply showed a current draw of 31 amps and a watt-hour reading of .071.

My math might be fuzzy, but 0.071W-hr suggests that you must have only run the motor for about 1.25 seconds (Power input of 320W for ~1.25 seconds equates to 0.071W-hr worth of power)
No, that was after several seconds of operation. I simply reported the number the unit gave me.
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Old Mar 25, 2013, 10:19 AM
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USA, NC, Huntersville
Joined Jul 2008
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Regarding the backwards prop suggestion, here is a video of my Superfly maiden with the prop accidentally installed backwards. You will notice around 1:10 in the video I tried a vertical takeoff and it barely had the power to do so...

"Lite" Superfly with prop on backwards (2 min 34 sec)


Now, here is a video of the same plane and motor once I got home and turned the prop back around and put a little paint on it for orientation purposes. Notice the difference in sound and the huge improvement in power.

Superfly "Litefly" VTO (0 min 35 sec)
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Old Mar 25, 2013, 12:40 PM
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Snohomish, WA
Joined May 2000
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Dan probably meant use a conventional prop and mount it with the numbers facing towards the nose. I doubt he meant normal mounting.
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Old Mar 25, 2013, 06:14 PM
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Quote:
Originally Posted by GBR2 View Post
Dan probably meant use a conventional prop and mount it with the numbers facing towards the nose. I doubt he meant normal mounting.
That's the setup I have currently have and the one recommended to me, so that's what I went with.

The hobby shop has a pusher in the same size, so I may pick it up and give it a try.
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Old Mar 26, 2013, 03:44 PM
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Quote:
Originally Posted by DismayingObservation View Post
That's the setup I have currently have and the one recommended to me, so that's what I went with.

The hobby shop has a pusher in the same size, so I may pick it up and give it a try.
Don't waste your money unless you just want to experiment. Same manufacturer, same diameter, same pitch = same performance. The only difference is that the motor needs to rotate in the other direction. You should expect to see no difference in performance, There's no way Dan meant for you to mount the prop "backwards" he had to be referencing in relation to a tractor setup.

Azarr
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Old Mar 26, 2013, 08:09 PM
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Quote:
Originally Posted by Azarr View Post
...There's no way Dan meant for you to mount the prop "backwards" he had to be referencing in relation to a tractor setup.
Now that makes more sense. It's common knowledge that a tractor setup is more efficient than a pusher configuration. "Cleaner" air for the prop.
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Old Mar 26, 2013, 08:30 PM
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United States, AK, Fairbanks
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The only sensible explanation for Dan's statement in this context is that the prop gets installed with the numbers facing toward the motor, so it's "backwards" relative to the motor... Which is an extraordinarily stupid way to describe it. The prop is not "backwards", the motor is.

I don't see why so many people have so much confusion about rear-mounted motors and props. This seems to be the single most confounding subject in the hobby
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Old Mar 26, 2013, 09:32 PM
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Des Moines IA
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I agree Dan's motors are the Bomb.
If you really want to liven it up go to 4s and an apc6x4 sport prop.
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Old Mar 26, 2013, 10:34 PM
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Originally Posted by eckace1 View Post
I agree Dan's motors are the Bomb.
If you really want to liven it up go to 4s and an apc6x4 sport prop.
Oh, yes. Hairy good fun.

If I pull that stunt, I'll upgrade the ESC.
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Old Mar 26, 2013, 10:36 PM
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Now that makes more sense. It's common knowledge that a tractor setup is more efficient than a pusher configuration. "Cleaner" air for the prop.
That's what it is. Viewed from the front, the numbers face forward and the motor is spinning counterclockwise.

I think I'll stay with that tractor setup and not worry about a pusher.
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Old Mar 26, 2013, 10:47 PM
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Originally Posted by DismayingObservation View Post
Oh, yes. Hairy good fun.

If I pull that stunt, I'll upgrade the ESC.
Ya you would need to do that but the first thing I would do with that wing is yank the motor mount off as it is so draggy and keeps the motor out of the air flow.

MD sells some great mounts for wings
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