Motors

[JAMMER]

What KV brushless motor would compare with a 65 turn motor? I checked Novack chart for brushless motors but I still do not know how to convert turns to KV. Any help would be greatly appreciated. Ed

[fhhhstix]

The KV rating is rpm per volt. A 4500KV at 7.2 V would be 32,000RPM. A 65 turn at 7.2V is about 10,000 to 12,000 RPM. 12,000 divided by 7.2V is approximately 1700 so you would need a 1700kv motor and I don't think they make one the smallest one Castle Creations makes is a 2400.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXAETU&P=7

This is at the normal 7.2V if you plan to use a higher voltage such as 12 volt it is impossible unless you gear it way down then you will have way more power than the pinions in the axles can take as you can strip them right off the shaft with a stock motor and gearing.

Travis

[JAMMER]

Thanks for the help Travis. I,ll get a hold of Castle tomorrow and see what they got. I am going to get a 7 to 1 reduction to use. Ed

[Espeefan]

Travis, 10,000 to 12,000 RPM seems a little high for a 65 turn motor, at least to me. I've never dynoed one, so I can't say for sure, but I see quite a few 55 turn motors rated for 8,000 RPM at 7.2 volts, and a 65 turn motor would surely be slower then a 55 turn, wouldn't it?

Ed, you might want to look at brushless out-runner motors. They usually run a lower Kv then what the in-runner motors do. I have a couple 800 Kv out-runners in one of my rock crawlers, but I needed to have an adpater plate made up so I could mount them to standard transmission plates. Some out-runners have a standard bolt pattern, others do not. Sometimes a really low Kv out-runner will also have a larger then normal motor shaft. In my case, my motors had 5mm shafts, but I was able to drill out the motor pinions easily, and make them work just fine.

Rather then look at the Castle Creation motors, take a look at these.

900 Kv out-runner, with a standard bolt pattern. No reduction necessary. If anything, you could always gear up, if it is to slow. Out-runners tend to have more torque and can easily handle a larger pinion gear, without hurting the performance.

http://holmeshobbies.com/product.php?productid=71&cat=19&page=1

Here is a 1100 Kv out-runner, that also bolts up to anything a 540 can motor will. Standard shaft as well. More torque then the motor above, and a little higher speed, yet still very slow.

http://holmeshobbies.com/product.php?productid=117&cat=19&page=1

Both of these will run with any brushless speed controller you like.

[fhhhstix]

Nate you are probably right my 55's run at 12000 14000 and the 85's I dynoed ran around 4500 to 6500 but this all depends on the motor does it have any timing or bushings compared to bearings. I have never had a 65 to run on the dyno. I have some integy 55 and 85 turn and they tend to be slower than higher end motors like novak or OHP. Mainly the comparison was just to show that you would need a low kv motor.

Travis

[JAMMER]

Nathan is this Holmes Hobbies in the states? Ed

[mtdriver]

Yes, Columbia MO, guys name is John, I have crawled with him a few times. Great guy.

[JAMMER]

Thank you for that info. Ed