P-Limited Motors - Im going to jump on the hot seat.

[Darin Jordan]

I was curious a since I've seen some pretty inexpensive on line. If I can turn a m447 on a AQ 1800, I figured I could adjust easily with one of these for spare.

Back to the mad scientist Darin Jordan... Nice data so far!

That 1500KV motor is the standard, "direct from Horizon Hobby", part... they are actually relatively "cheap"... $69.95, if I recall correctly.

Best motor in the bunch if you know how to tune a boat.

[JimClark]

Correct on the price http://www.horizonhobby.com/DYNM3835...11980000365447

That 1500KV motor is the standard, "direct from Horizon Hobby", part... they are actually relatively "cheap"... $69.95, if I recall correctly.

Best motor in the bunch if you know how to tune a boat.

[TRUCKPULL]

Also, what is the part # for the DYNM1500 You are testing please?

Hello Ray

Terry is correct, the part # is DYMN3835 1500Kv - 6 Pole

You want the NEW motor -all one color Blue
NOT the one with the gray barrel and the blue end caps.

The NEW one is even better then the old one, Better output wires also.
Look at the picture in Darin's post #537, it is the NEW motor.

Larry

[Darin Jordan]

Hey guys. I received a suggestion that I add a "% KV Drop" column so it might be easier to see just how much the load is affecting the RPM.

Here is the above chart with that adjustment. Does make it easier to compare.

Slide17_CHART.JPG

[Darin Jordan]

The NEW one is even better then the old one, Better output wires also.

Larry

The new one is also better than the original BJ26 one! :)

[ray schrauwen]

This http://www.ebay.com/itm/191717747608...%3AMEBIDX%3AIT

Picture my not be accurate???

[Darin Jordan]

This http://www.ebay.com/itm/191717747608...%3AMEBIDX%3AIT

Picture my not be accurate???

Same picture that's on the Horizon site. I don't know where these are coming from, however. Horizon ONLY has the good ones in stock.

The picture is NOT accurate. The picture posted above, with the heat shrink and better wires, is.

[ray schrauwen]

Thanks Darin!

[TRUCKPULL]

This http://www.ebay.com/itm/191717747608...%3AMEBIDX%3AIT

Picture my not be accurate???

Looks like the same picture that Horizon Hobby uses?????

Larry

[Darin Jordan]

It took way more time than anticipated to get all the loads just right on the next group of motors, but I got it worked out and was able to get very close to the loads tested for the P-LTD motors.

Tested the TURNIGY SK3 3659-1900, TP3660-1950, and LBP3660-1900. They all were loaded to 100-105A for 60-seconds. The Turnigy and the TP are clearly higher powered than any of the present P-LTD motors. At the same loads, they gain about the same temperature, but have ~2000 and ~1600 RPM higher. With the Turnigy and assuming a 3.0" Pitch Prop, that would equate to a 4mph advantage. I think I posted awhile back how a 1-MPH increase equates to over 1/4 lap over a race distance.

The Leopard LBP3660-1900 is about equivalent in performance to an AQ2030, but gains a tick more heat.

I still need to test the SSS3660 motors (1500, 1800, 1968) and I might retest the AQ1800 to increase it's amp-load to be a tick over 100, like the others.

Here are the graphs and updated data chart. I went ahead and hid the 3650-sized motors for now. They clearly can't be operated at these AMP loads.

TURNIGY SK3 3659-1900:
Slide18_TURNIGY_SK3_3659_1900.JPG

TP3660-1950:
Slide19_TP3660_1950.JPG

Leopard LBP3660-1900:
Slide20_LBP3660_1900.JPG

DATA CHART:
Slide21_3660_CHART.JPG

[zooma]

Darin, are you intentionally propping each motor for approx 100 amp loads to get the comparison data? If so, did you pick 100 amps because it's the typical draw of a P-limited race boat?

[Darin Jordan]

Darin, are you intentionally propping each motor for approx 100 amp loads to get the comparison data? If so, did you pick 100 amps because it's the typical draw of a P-limited race boat?

Basically, Yes. For example, my P-LTD OPC Lynx, with AQ2030, averages about 85A "continuous". For 2-Lap or it pulls more. Monos might pull more, etc. The idea is find out how much power these motors can put out reliably.

Also, it was asked why do I need to test EACH motor at 100A. My goal is to measure the motors ability to produce power. Power... WATTS... Horsepower... is determined by Voltage and Current (P = Voltage x Current). By getting each motor to 100A and attempting to maintain a similar voltage under load, EACH motor is putting out the same Power. From there, heat build-up, KV drop, Max RPMs, etc., can then be more directly compared. Ultimately, speed is determined by Power available, regardless of the KV or RPMs. How you put that power the the water is determined by those other factors (small prop vs. larger prop), but either way, performance potential is determined by the available power.

Hopefully all that makes sense.

Have the three TFL SSS motors left to test, and then I think I'll be done for now. At this point, I'm really only seeing ONE motor that could potentially "fit in" with the existing motors, and that would be the Leopard LBP3660-1900. I'd expect, if they had a 1500KV version, that might fit too. The TP and Turnigy have more power potential than the others. In trying to determine the correct 100A load for the Turnigy, for example, I made one 60second pull at over 115A continous, and the motor temps only went up to the low 140s... Also saw some other pulls where it was pulling over 135A, and the temp still didn't increase as dramatically, though it was starting to get "warm".

I can imagine that a couple of the options would be to: 1) Do nothing, let the class run as is and die off once motors aren't available, 2) Accept that the existing motors are fading off, approve some quality options, and let the class "re-level" itself over a year or so (which has the con of negating the present investments of most competitors in the short term), or 3) Approve the smaller 3650-sized motors and slow the class down that level. Probably maximum of 80A, or 4)... well... Not sure if there is a 4.

[ray schrauwen]

Thanks Darin. I have an idea what motor I'll use for club pond running and what I'll use for sanctioned events.

[rayzerdesigns]

if you were to ask me I have no problem slowing the class down, im not sure about others, but my p limited speeds are not far off p speedsand for those of you that don't know I am running nothing but the 1500s,.. my 1/10th scale modern was clocked at 59mph today in az club race..on a shorter than legal course..i wont say what my other hulls are running, but will be ready for nats

[Darin Jordan]

if you were to ask me I have no problem slowing the class down....

Yes, that's definitely option. Implementation would be interesting to say the least. A LOT of boats out there in P-LTD that simply wouldn't be suitable for the lower power.

But, it's a path to consider.