Justgofly 500XT

Dr Kiwi · Mar 21, 2007, 07:09 PM

Vinnie sent me a new motor to play with - a 68g 500XT. The model he sent was fitted with a 12-magnet bell, making it ~900Kv. Like all his 500 line, simply replacing the bell with the 6-magnet version, converts this 500XT into a much higher Kv motor (~1.7x - thus 1685Kv?).

I have run it with only a few props so far (7x6 APC SF through 11x7 GWS HD) because I was actually using it as a "trial horse" to calibrate a new Dr Kiwi Mk III stand I had just made for "Steve". I'll try a few more props, then switch bells to see how it performs in its far "hotter" version.

Like all Justgofly motors it is beautifully machined, and pretty much packed with copper in the windings (I don't know the details of winds and gauge, though it is obviously fairly small gauge, wound as multistrands). The cranberry color is very tasteful!

It has incredible cogging - exactly whether/how this affects performance, I know not - but those magnets must be strong! It ran very smoothly, with a momentary high pitched whine at start up.

Just glancing over the limited data I have, this 500XT seems somewhat comparable to the admittedly slightly lighter (53g) Hyperion Z2213-24. I'm a bit puzzled that even with apparently slightly higher Kv (900 v. 850), with the same prop, the 500XT draws a little less current than does the Hyperion - but, be that as it may, its calculated "efficiency" [as measured by g/W] is somewhat better across the board. I looked also to compare the 500XT to a Komodo KH2413-10 (63g/823Kv) - not surprisingly the lower Kv Komodo draws quite a bit less than the 500XT with the same prop, but if one compares g/W when obtaining the same thrust from that prop - the 500XT was marginally ahead again.

I tried some no-load runs (after using a Sharpie to produce two black bands on the shiny bell) and then used Peak Effic. to calculate Kv and Rm. No matter which figures I entered I got fairly consistent estimates of ~900Kv and ~0.222 ohms. I also tried Vintage1's calculator and got slightly lower figures (~880-890) for Kv, but similar Rm (~0.22 ohms). While using Peak Effic. I graphed the 500XT and the program indicated pretty decent efficiency - just over 80% with small props, and still around 65-70% with larger ones closer to its probable max amp/watts limit (??~15A/~160W).

All in all, this is a well-made motor which produces useful power with, say, a 10x6 GWS HD [27.6oz @ 42.6mph, at a respectable 6.4g/W - from 11.20A @ 10.9v = 122W] and if WOT was used in bursts, it could probably be asked to get even more, quite safely, from an 11x7 GWS HD [~33oz @ 43mph - from ~15A @10.9v = ~160W].

That's enough for now!

Cheers, Phil

byhsu · Mar 21, 2007, 11:42 PM

Is this an outrunner? What are the dimensions of the motor?

Thanks

JustGoFly · Mar 21, 2007, 11:53 PM

Nice review Dr Kiwi - as always. The kind words are just why you are an icon in this industry and keep us motor guys honest. If you get time to look at 12x8 - I'd appreciate your opinion on it.

The pictures of the motor look HUGE -

- you're going to have to find someone with bigger hands to hold the motor when you photograph it

ByHsu

Vinnie

byhsu · Mar 22, 2007, 12:00 AM

So this is about the same size as a Hacker A30-28S?

Dr Kiwi · Mar 22, 2007, 10:14 AM

Well Vinnie, it is all relative - here are a few other motors which make your 500XT look either tiny or monstrous!

Work in Progress · Mar 22, 2007, 11:46 AM

I like the look of this motor. Looks like an interesting alternative to the Axi 2217/20 at two thirds the price. A good motor for a scale warbird that would run on a geared 480 or a mild geared 600 setup.
At lower power levels it makes a good comparison with the (perfectly okay) 400 XT. Using Phil's data, on a 9x5HD, the 400XT consumes more watts to turn the prop at significantly lower RPM than the 500XT. Both at around the 70 watt mark. That's not something one would want to do as a 3D flier but for many scale models, where you may need noseweight anyway, using a bigger motor propped down to a very modest power level can be a very good way to get an efficient result.

byhsu · Mar 22, 2007, 11:49 AM

WIP:

Are you talking about the Esskay 400XT?

Work in Progress · Mar 22, 2007, 11:58 AM

Yep. Out of the same family of motors as the various hotter 400s that JustGoFly sells.

Dr Kiwi · Mar 22, 2007, 12:52 PM

Vinnie's 64g 450XT (950Kv) is another alternative.

byhsu · Mar 22, 2007, 01:06 PM

What is the peak watts for the 450XT?

JustGoFly · Mar 22, 2007, 03:00 PM

Peak Watts on 450XT is 180.
I have not measured peak watts on 500XT yet - but am expecting it to be higher than 450XT.

500XT is very new - Dr. Kiwi got the first available. I intend to put one on a Slow Stick and will push it until it shows me it's limit. Bench testing sometimes shows that a motor can handle larger props - but use of that motor requires it to run as the voltage degrades and sometimes that stress is enough to limit the prop down one size.

I do field testing - and welcome customer feedback - before saying with confidence it can handle a larger prop. Initially the 450XT showed it could handle a 11x7, but we dropped the spec to 10x6 since that is the right size to get the motor to last full throttle for a full battery pack without burning out.

Field testing has been very limited due to weather. Dr. Kiwi - thanks for your help in looking at this motor.

Vinnie

Work in Progress · Mar 22, 2007, 03:23 PM

Doctor K, if you get chance to try some coarser props, e.g. 9x7.5 either APC-E or HD, I would be very interested.

Dr Kiwi · Mar 22, 2007, 04:30 PM

Quote:

Originally Posted by JustGoFly

Peak Watts on 450XT is 180.
I have not measured peak watts on 500XT yet - but am expecting it to be higher than 450XT.

500XT is very new - Dr. Kiwi got the first available. I intend to put one on a Slow Stick and will push it until it shows me it's limit. Bench testing sometimes shows that a motor can handle larger props - but use of that motor requires it to run as the voltage degrades and sometimes that stress is enough to limit the prop down one size.

I do field testing - and welcome customer feedback - before saying with confidence it can handle a larger prop. Initially the 450XT showed it could handle a 11x7, but we dropped the spec to 10x6 since that is the right size to get the motor to last full throttle for a full battery pack without burning out.

Field testing has been very limited due to weather. Dr. Kiwi - thanks for your help in looking at this motor.

Vinnie

I just put 216W through the 500XT with a 12x8 GWS HD and it was not at all happy. And on a slightly extended run with an amp hungry 11x5 Graupner SF at around 170-180W it got very hot.

It managed ~150W okay with both a 10x5 Graupner SF and an 11x5.5 APC E.

Obviously if you pack holds closer to 10v than the 10.9v I was using, things would look better with any/all of these props.

I'll post the full tables shortly.

By the way Vinnie, should this 500XT have a circlip in that groove at the base of the shaft? Mine doesn't have one? I was contemplating removing the 12-magnet bell and fitting the 6-magnet - in the absence of a circlip do I just push the shaft back through?

Cheers, Phil

JustGoFly · Mar 22, 2007, 09:05 PM

Phil,

Thanks for running the 12x8. I thought it would be too big - but worth the try.

I think you got the Tractor version. I intentionally left off the Clip since you would be changing bells and the clip is not needed on a tractor. I can certainly send you clips as you would need them for pusher bells. Sorry for the confusion. The C Clip comes normally on both tractor and pusher, but only really needed on the tractor when run on the rear of the plane/wing.

Vinnie

Dr Kiwi · Mar 22, 2007, 10:44 PM

Thanks Vinnie - I knew it wasn't really required, even on my pusher stand, but I needed to be sure there wasn't some other patented device in there that I would destroy if I pressed out the shaft and bell! If it had started moving backward during testing you can be sure I'd have put a clip on! I need no more "Quelle catastrophe" incidents.

Mar 21, 2007, 07:09 PM	#1
Dr Kiwi Registered User Join Date: May 2003 Location: Chattanooga, Tennessee, United States Posts: 21,974	Justgofly 500XT Vinnie sent me a new motor to play with - a 68g 500XT. The model he sent was fitted with a 12-magnet bell, making it ~900Kv. Like all his 500 line, simply replacing the bell with the 6-magnet version, converts this 500XT into a much higher Kv motor (~1.7x - thus 1685Kv?). I have run it with only a few props so far (7x6 APC SF through 11x7 GWS HD) because I was actually using it as a "trial horse" to calibrate a new Dr Kiwi Mk III stand I had just made for "Steve". I'll try a few more props, then switch bells to see how it performs in its far "hotter" version. Like all Justgofly motors it is beautifully machined, and pretty much packed with copper in the windings (I don't know the details of winds and gauge, though it is obviously fairly small gauge, wound as multistrands). The cranberry color is very tasteful! It has incredible cogging - exactly whether/how this affects performance, I know not - but those magnets must be strong! It ran very smoothly, with a momentary high pitched whine at start up. Just glancing over the limited data I have, this 500XT seems somewhat comparable to the admittedly slightly lighter (53g) Hyperion Z2213-24. I'm a bit puzzled that even with apparently slightly higher Kv (900 v. 850), with the same prop, the 500XT draws a little less current than does the Hyperion - but, be that as it may, its calculated "efficiency" [as measured by g/W] is somewhat better across the board. I looked also to compare the 500XT to a Komodo KH2413-10 (63g/823Kv) - not surprisingly the lower Kv Komodo draws quite a bit less than the 500XT with the same prop, but if one compares g/W when obtaining the same thrust from that prop - the 500XT was marginally ahead again. I tried some no-load runs (after using a Sharpie to produce two black bands on the shiny bell) and then used Peak Effic. to calculate Kv and Rm. No matter which figures I entered I got fairly consistent estimates of ~900Kv and ~0.222 ohms. I also tried Vintage1's calculator and got slightly lower figures (~880-890) for Kv, but similar Rm (~0.22 ohms). While using Peak Effic. I graphed the 500XT and the program indicated pretty decent efficiency - just over 80% with small props, and still around 65-70% with larger ones closer to its probable max amp/watts limit (??~15A/~160W). All in all, this is a well-made motor which produces useful power with, say, a 10x6 GWS HD [27.6oz @ 42.6mph, at a respectable 6.4g/W - from 11.20A @ 10.9v = 122W] and if WOT was used in bursts, it could probably be asked to get even more, quite safely, from an 11x7 GWS HD [~33oz @ 43mph - from ~15A @10.9v = ~160W]. That's enough for now! Cheers, Phil Attached Thumbnails 54.6 KB · Views: 232 39.9 KB · Views: 213 123.4 KB · Views: 217 123.2 KB · Views: 216 126.4 KB · Views: 185 41.9 KB · Views: 166 72.0 KB · Views: 253 Last edited by Dr Kiwi; Apr 08, 2007 at 10:07 AM.

Mar 22, 2007, 10:14 AM	#5
Dr Kiwi Registered User Join Date: May 2003 Location: Chattanooga, Tennessee, United States Posts: 21,974	Well Vinnie, it is all relative - here are a few other motors which make your 500XT look either tiny or monstrous! Attached Thumbnails Clockwise from left: Hyperion Z2213-24, Justgofly 500XT, Axi 2212/34, Mega 600/20/8 96.9 KB · Views: 215 Justgofly 500XT in center: The rest, clockwise from top left: Scorpion 2215/22, Microdan 2003/FP3, Microdan 2505 3D, Elerc C20 88.3 KB · Views: 217

Mar 22, 2007, 11:46 AM	#6
Work in Progress Light and floaty does it Join Date: Sep 2004 Location: Cambridge, Great Britain (UK) Posts: 2,829	I like the look of this motor. Looks like an interesting alternative to the Axi 2217/20 at two thirds the price. A good motor for a scale warbird that would run on a geared 480 or a mild geared 600 setup. At lower power levels it makes a good comparison with the (perfectly okay) 400 XT. Using Phil's data, on a 9x5HD, the 400XT consumes more watts to turn the prop at significantly lower RPM than the 500XT. Both at around the 70 watt mark. That's not something one would want to do as a 3D flier but for many scale models, where you may need noseweight anyway, using a bigger motor propped down to a very modest power level can be a very good way to get an efficient result. Last edited by Work in Progress; Mar 22, 2007 at 11:49 AM. Reason: addition...

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sold Brushless Tigermoth 400 w/justGoFly 500xt. Or w/o motor. Price drop!	1987tc	Aircraft - Electric - Airplanes (FS/W)	18	Apr 15, 2007 10:20 PM

Mar 21, 2007, 11:42 PM	#2
byhsu Registered User Join Date: Sep 2006 Location: CORONA, CA, USA Posts: 266	Is this an outrunner? What are the dimensions of the motor? Thanks

Mar 21, 2007, 11:53 PM	#3
JustGoFly Rochester, NY Join Date: May 2004 Location: Rochester, NY Posts: 1,619	Nice review Dr Kiwi - as always. The kind words are just why you are an icon in this industry and keep us motor guys honest. If you get time to look at 12x8 - I'd appreciate your opinion on it. The pictures of the motor look HUGE - - you're going to have to find someone with bigger hands to hold the motor when you photograph it ByHsu Vinnie

Mar 22, 2007, 12:00 AM	#4
byhsu Registered User Join Date: Sep 2006 Location: CORONA, CA, USA Posts: 266	So this is about the same size as a Hacker A30-28S?

Mar 22, 2007, 11:49 AM	#7
byhsu Registered User Join Date: Sep 2006 Location: CORONA, CA, USA Posts: 266	WIP: Are you talking about the Esskay 400XT?

Mar 22, 2007, 11:58 AM	#8
Work in Progress Light and floaty does it Join Date: Sep 2004 Location: Cambridge, Great Britain (UK) Posts: 2,829	Yep. Out of the same family of motors as the various hotter 400s that JustGoFly sells.

Mar 22, 2007, 12:52 PM	#9
Dr Kiwi Registered User Join Date: May 2003 Location: Chattanooga, Tennessee, United States Posts: 21,974	Vinnie's 64g 450XT (950Kv) is another alternative.

Mar 22, 2007, 01:06 PM	#10
byhsu Registered User Join Date: Sep 2006 Location: CORONA, CA, USA Posts: 266	What is the peak watts for the 450XT?

Mar 22, 2007, 03:00 PM	#11
JustGoFly Rochester, NY Join Date: May 2004 Location: Rochester, NY Posts: 1,619	Peak Watts on 450XT is 180. I have not measured peak watts on 500XT yet - but am expecting it to be higher than 450XT. 500XT is very new - Dr. Kiwi got the first available. I intend to put one on a Slow Stick and will push it until it shows me it's limit. Bench testing sometimes shows that a motor can handle larger props - but use of that motor requires it to run as the voltage degrades and sometimes that stress is enough to limit the prop down one size. I do field testing - and welcome customer feedback - before saying with confidence it can handle a larger prop. Initially the 450XT showed it could handle a 11x7, but we dropped the spec to 10x6 since that is the right size to get the motor to last full throttle for a full battery pack without burning out. Field testing has been very limited due to weather. Dr. Kiwi - thanks for your help in looking at this motor. Vinnie

Mar 22, 2007, 03:23 PM	#12
Work in Progress Light and floaty does it Join Date: Sep 2004 Location: Cambridge, Great Britain (UK) Posts: 2,829	Doctor K, if you get chance to try some coarser props, e.g. 9x7.5 either APC-E or HD, I would be very interested.

Mar 22, 2007, 09:05 PM	#14
JustGoFly Rochester, NY Join Date: May 2004 Location: Rochester, NY Posts: 1,619	Phil, Thanks for running the 12x8. I thought it would be too big - but worth the try. I think you got the Tractor version. I intentionally left off the Clip since you would be changing bells and the clip is not needed on a tractor. I can certainly send you clips as you would need them for pusher bells. Sorry for the confusion. The C Clip comes normally on both tractor and pusher, but only really needed on the tractor when run on the rear of the plane/wing. Vinnie

Mar 22, 2007, 10:44 PM	#15
Dr Kiwi Registered User Join Date: May 2003 Location: Chattanooga, Tennessee, United States Posts: 21,974	Thanks Vinnie - I knew it wasn't really required, even on my pusher stand, but I needed to be sure there wasn't some other patented device in there that I would destroy if I pressed out the shaft and bell! If it had started moving backward during testing you can be sure I'd have put a clip on! I need no more "Quelle catastrophe" incidents.