C-20 PRO 2050Kv @ Graysonhobby.com--Micro Park Jet Motor???? - RC Groups
Thread Tools
Feb 05, 2008, 03:11 PM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
Mini-Review

C-20 PRO 2050Kv @ Graysonhobby.com--Micro Park Jet Motor????


Hello all,

I recently purchased a C-20 PRO 2050Kv motor from Graysonhobby and I am throughly impressed with the test results. I have put these results into a pdf form for easy viewing. My larger props were limited for 2s due to I am a jet person and I NEED the power of 3s.

The weight is exactly what grayson says it is. Right around 26g. There are a few things that I disagree with though. The test results that they show do not show any APC props (which is what I used) and they also do not show any different size props. The next thing is that they say it is a 6 pole motor when you can clearly see by the pic that the stator has 9 teeth and it has 12 magnets (which have 100% coverage by the way) so I do not know where they got 6 poles from. The one down fall is that it has a 7mm bearing tube. They send it with a firewall mount but I like to use the Tower Pro 8mm bearing tube stick mount. To fix this problem I used a piece of aluminum tube I had laying around and cut a slit in the side so it can clamp around the bearing tube. This should give you enough metal to use the TP 8mm mount. If not you can grind down one side of the inside of the clamp on the TP 8mm mount.

I am personally using this on a Jetset44 F-18 @ 77% with a APC 5.25x4.75. It should have unlimited vertical and a decent speed at a low amp draw.

Fanatic
Last edited by Foam Fanatic; Feb 07, 2008 at 12:42 PM.
Sign up now
to remove ads between posts
Feb 05, 2008, 04:16 PM
Registered User
Dr Kiwi's Avatar
Very interesting since I am just about to test the 1550Kv version of this motor!

https://www.rcgroups.com/forums/showthread.php?t=813273

My problem was that I simply could not undo the set screw on the attached mount - yes, I had the correct Allen Wrench, but I think they must have used Loctite. Nor could I budge those on the tiny C10, so I've had to mount them both firewall style on my test stand.
Feb 06, 2008, 07:58 AM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
Kiwi,

I had no problem taking the firewall mount off. It almost fell off of my motor.

Fanatic
Feb 06, 2008, 08:38 AM
Registered User
Dr Kiwi's Avatar
You lucky dog! I actually tore a 1.6mm Allen ball wrench from its handle, and the set screw still wouldn't budge. With the C10 the recess (0.035"/0.9mm) stripped when I applied the same sort of pressure.
Feb 06, 2008, 10:14 AM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
I don't use ball head wrenches. I learned my lesson from my R/C car days. They just strip out the heads. I have a set of high quality OFNA metrics and Team Losi standards. They haven't failed me yet.

I did find one problem with set screws though. The set screw that holds the rotor to the shaft was stripped out when I got it. The screw still holds but not enough for me to trust it on my plane. It will get fixed before it flies.

Fanatic
Feb 06, 2008, 11:32 AM
Same Day Delivery
mike3976's Avatar
The next thing is that they say it is a 6 pole motor when you can clearly see by the pic that the stator has 9 teeth and it has 12 magnets (which have 100% coverage by the way) so I do not know where they got 6 poles from.

The magnets could be arranged NNSSNNSSNNSS, this would give you 6 poles.

Nice performance @ 12 amps with the 5.5x4.5, 16 oz. thrust, 71 mph pitch speed! Not Bad For 20 Bucks!!!
Last edited by mike3976; Feb 06, 2008 at 11:38 AM.
Feb 06, 2008, 12:09 PM
Registered User
Dr Kiwi's Avatar
I have both regular hex and ball wrenches - tried both. As you found with the C20, The setscrew holding the bell on my C10 was stripped, but I found another 2mm set screw which held it pretty well.

I've just had the C10 and C20 on the stand:

The C20 -1550 was pushed too hard for long WOT with an 8x4 GWS HD on 3s, but before it became an immersion heater, it got me 555g (19.5oz) @ 40mph from 11.3A/121W.
It was far happier with a 7x3.5 GWS HD: 424g (14.9oz) @ 44mph from 7.05A/77W.
Feb 06, 2008, 12:41 PM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
mike3976,

That might be how they are arranged. I never tested polarity of the magnets. Maybe Kiwi can test one while he has them out. Also, the # of poles is related to the magnets? I thought it was related to the # of stator teeth. Please correct me on what poles are.

Yes I agree it does have a lot of bang for the buck.

Kiwi,

That's great that you got the 1550Kv cause I was going to buy one to test as well. You just saved me the money of purchasing one. I really have no use for that in a jet.

I am however thinking about buying another and trying to do a custom wind to see if I can get the Kv around 2200-2300. I wish I had your deal and get motor sent to me left and right.

Fanatic
Feb 06, 2008, 12:52 PM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
If you look at the pic you can see that the magnets are alternating North and South. I just now noticed that.

Fanatic
Feb 06, 2008, 02:08 PM
Registered User
Dr Kiwi's Avatar
That might be how they are arranged. I never tested polarity of the magnets. Maybe Kiwi can test one while he has them out. Also, the # of poles is related to the magnets? I thought it was related to the # of stator teeth. Please correct me on what poles are.

Poles = # of magnet poles - NOT stator teeth/arms. This C20 is 12 magnet (alternating N/S)... 6 magnet poles as Mike indicated would be 6 pairs.

If 76mph is enough for a jet, with a Zagi Carbon 5.1x4.9, the 1550Kv gets you 14oz @ 76mph from just 8.75A on 4s [14.1v/123W].
Last edited by Dr Kiwi; Feb 06, 2008 at 05:23 PM.
Feb 06, 2008, 03:12 PM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
Kiwi,

Thanks for clarifying that for me.

Now you have wheels turning in my head on whether I should purchase a 1550Kv. The low amp draw will allow me to put in smaller batts in series to get me up to 14V. The weight might be the same as a larger 3s with the 2050Kv. So many possibilities.

Fanatic
Feb 06, 2008, 05:23 PM
Registered User
Dr Kiwi's Avatar
If you need more persuasion the 14v run with the Zagi (even though it reached 123W) didn't get the motor as hot as it got on fewer watts on 3s.

Have you test run the 2050 with a 7x3.5 or 8x4... I ask because Grayson has performance figures for the 1550Kv on his website and they do not match, at all, what I get. I think he must have 2050 figures up there.

Oh yes, the 1550 is not 1550Kv... Motocalc and I make it ~1735Kv. A 1550Kv motor cannot get you 16680rpm @ 10v no-load!
Feb 07, 2008, 07:53 AM
Respect My Authauriti!!!!
Foam Fanatic's Avatar
I think I might have to get me one to play around with.

I did run a APC 7x4 and a 8x4 but only on 2s. The 6x4 on 3s was pushing it I thought b/c it got pretty warm after 20-30 seconds of WOT.

If you look at the figures on Grayson for the 1550 and the 2050 they are the same exact figures. Somebody screwed up somewhere.

How do you calculate the KV at no load? B/C my figures might be off.

Fanatic
Feb 07, 2008, 08:11 AM
Registered User
vintage1's Avatar
6x4 on 2s is about right, and 5.5x4.5 is just about on on 3s.

For safe operation.


On the lower KV a 7x4 on 2s is useable, and a 6x4 on 3s.
Feb 07, 2008, 08:14 AM
Registered User
Dr Kiwi's Avatar
All you need for Motocalc to estimate Kv is no-load current and rpm at a certain voltage, and a current and rpm reading, for any prop you choose, at roughly the same voltage.

To use Peak Effic. or Vintage1's calculator, you need no-load current (but not rpm), then a current/rpm reading for each of two different props at roughly the same voltage at which you obtained Io.

For Drive Calc., you need no-load current/rpm measurements at two different voltages, and then you enter as many as six current/rpm measurements for different props.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Video Littlescreamer Park Jet Motor in action! rvincent Electric Plane Talk 7 May 13, 2006 05:21 PM
Sold Little Screamer Park Jet Motor jhamm Aircraft - Electric - Power Systems (FS/W) 3 Apr 26, 2006 12:28 PM
Sold Little Screamer Park Jet Motor jhamm Aircraft - Electric - Power Systems (FS/W) 5 Apr 26, 2006 11:36 AM
Discussion Jeti 18 esc with Littlescreamer Park Jet motor jhamm Power Systems 0 Apr 19, 2006 10:17 PM
Wanted LS Park Jet motor or Lens RC 17 turn luger007 Aircraft - Electric - Power Systems (FS/W) 0 Apr 11, 2006 05:56 PM