I have tried to compare the performance of a dozen "Small Motors" - nine of them under the magic ounce (28.4g), the other three are under 40g.

In this post there is a page of rambling Analysis. In the two which follow,there is a Table giving the Motors' full names (abbreviated in the Graphs which come at the end), their weight and Kv (if known), and the suggested or perceived Maximum Amp draw - and three pages of Bench Test Performance Data, using various 5"-9" props.

Finally, because I know you hate to wade through screeds of data tables, I've tried to summarize data for each motor and prop size in Watts/Thrust graphs.

Read on!

A comparison of CD-ROM type and other small brushless motors (23g - 39g)

This is, very much, an apples versus oranges exercise, since every motor I have available for testing has, as far as I can ascertain, a different Kv. I have documented performance data for a dozen small motors, but of those, for only five do I actually know the Kv as indicated by their manufacturers.

However, if one looks at enough performance data for the same prop/same voltage one can, intuitively, rank the motors in order of Kv, and even extrapolate approximate numbers for those “unknowns” which clearly fall between certain “knowns”.

For those props for which I have sufficient comparative data, I have given measurements for the standard parameters for each of the motors for which that particular prop is suited (i.e. it draws less than the maximum allowable amp draw).

The impetus for this exercise (hopefully not one in futility) was to determine how good the Littlescreamer “Purple Peril” or “Purple Killer” [Bob Vincent's prototype] was in relation to other motors of similar size. The difficulty is obvious – since almost all the “competitors” are of lower Kv, yet cannot cope with the current draw which this Littlescreamer seems to be happy with (and particularly is “cool” with), the whole thing (at least up to the 8x4 GWS HD mark) is weighted heavily in the LS PP’s favor. The one other motor which is to all intents and purposes its equal is the slightly heavier (32g) Torque 34T/1520Kv – despite the fact that one motor is a double wound 17T (34T) and the other is “a lot less than that” (proprietary secret!) the incredible closeness of these two motors’ performances suggests that their Kv’s, and their mechanical and electrical efficiencies, are very close (I estimate ~1500Kv for the LS de novo PP).

With larger props, the lower Kv motors, like the 39g Mega 400/7/12, will come into their own, but only if they can deal with the amp draw. With its low Kv, the LS de novo PM can run a 9x5 GWS HD on 3s -even though that took it to over 8A, this remarkably cool-running motor was still only getting a little warm (35ºC) – with a gentle thumb on the throttle, it might well be just fine. The LS de novo PS would not! It seems that the LS de novo PP can cope with as much as 10A, even 12A, in the short term, so its limits perhaps could be further tested, but clearly its limit with a prop as big as a 9x5 GWS HD is 2s! With smaller props on 4s, several other low Kv motors excel [notably the Ikarus 2023011 (1300Kv) with the 5.1x4.9 Zagi Carbon and the LS de novo PM (perhaps ~1100Kv) with the 7x4 APC SF] – yet still do not exceed their modest amp limits.

One interesting point of contrast is the difference between the pre-production “LS de novo PM” data compared with the production “LS de novo PS” data – these are, apparently, two motors with different winds and the “cooler” PM version outscores the slightly “hotter” PS version in terms of efficiency (g/W) at every level. As expected the PS “runs out of steam” with the 9x5 GWS HD.

The LensRC 25T and MAE 25T, and the Python 30, would, one would think, be able to turn large props, but they are limited by amp draw and don’t seem to have the torque to be happy with the size of prop their low Kv’s would suggest they could turn. They do well with small props, but they all get hot, far too fast for comfort, when burdened with the larger props.

I leave it to you guys to extract what you want from this mass of data. Please be aware that there will inevitably be inaccuracies and conflicts – these data are derived from a bunch of tests all on the same test rig, but at different times under different conditions [ambient temperature and humidity clearly make a significant difference].

Cheers, Phil

P.S. This is in a new thread only because I saw that the second LS thread had reached the critical 499 posts!

Here is the Table you'll need to decipher the abbreviations in the Graph Legends - and the Data Tables

Finally - the Graphs:

To me one of the most interesting points that the LS purple has the same efficiency at the same thrust on 2s, 9050 as the LS production has on 3s, 8040. To get that 15-16 oz thrust from the purple is seriously pushing a Phoenix 10, while the production is safely used with a Phx10 for the same thrust.

Hi Adam - The PP is certainly a hot wind, and I would argue that it is better served being used for smaller props - the PS really struggles a bit too much with that 9x5 though - and it gets fairly hot with it - the PM seems to me the best Littlescreamer for a 9x5. On 3s it gets more thrust, more efficiently, than either of the others and at only just over 8A its fine for your PH10.

The idea of the PP was to use it on small 3D planes, with 9x5 on 2s, to save the weight of the extra cell.

Cheers, Phil

Great tests as usual Phil.

One motor I don't see talked about too much are the smallest 2 MPJ outrunners - they are blue and red like thier big bros but are sub-1oz motors. You played with those yet?

How about the heavier BP21 and BP12 motors? Any tinkering there?

Off topic but - received my Hyperion 2213/20 motor today. Will bench test it later in the week and post photos and results. No thrust stand but I can give RPMs and current figures using 3s packs hoc. look for the new topic in a couple of days.

Sorry LT - I have not got my hands on any MPJ outrunners yet - any loaners out there? As for the Hyperion - a kind gentleman is going to lend me his brand new one when it arrives. Can't wait to see it. I'm waiting for MP J Gold Connectors to become available thru aircraft-world - if I can find out how good the Hyperions are before hand, then I might have to add one or two to the order!

Now, LT, it really is time you built yourself a Dick Hanson Test Stand. If I had a few hours to spare, I'd produce one for you.

Cheers, Phil

Yeah I know - I am a slacker. Trouble is I have a hard enough time finding time to build and repair all the planes on my bench. I think I like fooling with the motors almost as much as the planes. If I build a proper test stand I might forget how to fly because I'd be having too much fun learning about motors props and thrust.

My impression of the Hyperion is that it looks extremely well made. Hope it performs like the datasheet says.

The packaging is very professional - best I have seen. Comes in a box with a dense rubbery foam with a cut out for the motor.

I'll post more impressions, photos, and some tests later in a new thread. I was going to get a Torque motor based on your findings but I had to be different and try something that nobody had yet. Oh well that's me. I recall, we both got sort of burned with the little microtex but it was a learning experience and both of mine were accepted back by the retailers. Hope this Hyperion turns out better than that did. It certainly has the physical characteristics of a quality motor but the proof is in the spining.

The LensRC 25T and MAE 25T, and the Python 30, would, one would think, be able to turn large props, but they are limited by amp draw and don’t seem to have the torque to be happy with the size of prop their low Kv’s would suggest they could turn. They do well with small props, but they all get hot, far too fast for comfort, when burdened with the larger props.

This is news to me.......The MAE Motor regularly swings a 10x6 HD prop. If they were getting to hot, I would be getting them back for replacement. I'm not. There is a difference between "hot" and "too hot". If the motor does what I claim it does, and it continues doing it, why must you keep posting this?

I respectfully ask you, DrKiwi, to not put my products in a bad light in order to promote someone else's in the future.

Len
LensRc

Why not just let the numbers speak for themselves. Kiwi just posted numbers is all.

Maybe the subjective "far too fast for comfort" should be replaced with some temp rise over time data? But I never found Doc's tests to be bias in the way you imply. In fact I have seen several positive posts regarding the lensrc motors from Dr K. including some outright recomendations to others to purchase your motors.

No good deed goes unpunished I guess.

Originally Posted by lensrc

This is news to me.......The MAE Motor regularly swings a 10x6 HD prop. If they were getting to hot, I would be getting them back for replacement. I'm not. There is a difference between "hot" and "too hot". If the motor does what I claim it does, and it continues doing it, why must you keep posting this?

I respectfully ask you, DrKiwi, to not put my products in a bad light in order to promote someone else's in the future.

And I feel that if you have made an error in your specification you should not shoot the messenger; Dr kiwi tested, and showed the table of results, for motors tested within your specifications. Based on these measurements he has made the justified and absolutely correct conclusions.

There is no way that you can drive a 10x6 HD prop and remain within your 6-7A limit - note that on a 9x5 HD the current draw was 6 and 5.6A respectively. I'll also go further in that on the only data you provide on the 25 turn is:

25 Turn- 10.5+ Ounces of thrust with 8x4 GWS DD prop, approximately 5 amps on 3S1P LiPoly, 11+ Ounces of thrust with 9x5 GWS DD prop, approximately 6 amps on 3S1P Lipoly

This is what Dr Kiwi tested to.
Your statement above therefore is incorrect if you are to maintain your specification. If you feel that 10x6 is a correct prop for this motor then stand by your statement and increase your rated current; but also be prepared to replace under warranty when people fry the motors if this current is reached.

In summary; Dr Kiwi has provided unbiased conclusions based on verifiable test data. If you believe the stated rating of your motor is incorrect then *you* as a manufacturer have the ability to change specification.

Keep up the good work Dr Kiwi!

Rod

P.S. Dr Kiwi; can I get a copy of the measurements with these props for incorporation into ThrustXL like the other data?

Dr Kiwi's statement was basically "it wont swing a large prop", not "it wont swing a large prop on 3s." I know it will not swing the 10x6 on 3 cells. I never said it would. MAE wanted a motor that would swing a big prop on 2 cells. The motor does that. Randy at MAE has told me he is using an 11x7 on 2s.
As I said the motor does what it was concieved to do. He has sold close to a hundred of them. I am not getting them back for rewinds. This post reads like the motor wont do it at all. This is the second time DrKiwi has said my motors run too hot. This is his opinion, not fact. If the motor does what it was concieved to do, what does it matter if it runs at a higher temperature?

Len

Rod,
There is no data on my website concerning the motor I am refering to. I dont claim the 25t motor I sell on my site will swing a 10x6, I am talking about the MAE motor, sold at Model Airplane Enginering. I produce this motor. They are two different motors.
Also, the data on my website is based on my tests, not DrKiwi's.
Len