Neu 1509 update PLEASE..

[lincpimp]

Ok, heres my take on the motor size question. I have not run a neu motor much, and only have one, a 1515 1.5d. I have run a crap load of other motors, and have formed the following guidelines for myself.

General belief is that we should be running motors around 35k rpm. That applies to feigao xl cans, as the are not very effecient. The higher quality motors, neu, lehener hacker c50, medusa, etc, can be run at higher rpms.

Here are my guidelines, larger motors like a 1515 can be run up to 40k rpm to provide good temps and will provide more than enough power to push a heavy truggy or MT to the 40mph range, or pull suitable racing gearing.

Smaller motors can be spun faster, like 50k rpm, and geared lower. That will provide similar power to the larger motor that is spinning slower with taller gearing. The feel will be different, no doubt about that. A smaller motor can spin up faster, and the lower gearing will help make up for less torque compared to the larger motor. Still not the same as the large torque motors, but if the smaller motor is in a lightweight vehicle, it will provide serious acceleration, and not draw too man amps.

I would say that a 1509 in a buggy would be fine, but you will want to get a higher kv than you would with a 1512 or 1515, and gear it lower to achive the same speed. Keeping weight down will also be a good idea, but you are on the right track with that already.

I run a hacker c50 8l motor in my hyper7. It is similar in size to a l can feigao, so somewhere in between a 1509 and a 1512. It has a kv of around 3000 and I run it on 4s lipo. So I am turning it around 45k rpm max. It is geared for 40mph, and it does not get hot, or create too much heat in the mm or the lipos. It is not as effecient as a neu, but definately much better than a feigao. I would rank it with the medusa 60mm motors. I need to do more testing with the medusa motors, but they seem to be an excellent choice for a buggy.

So for 4s running a 3000-3300 kv 1509 would be my choice. Something like 11 or 12 tooth pinion and a 46t spur should get decent track speeds.

[othello]

As lincpimp pointed out: a smaller motor can achieve similar power levels then a bigger motor when you rev it higher. I started with a Neu 1512/2Y (1400kv) in my truggy which was geared 1:16,8 and it reached 38000rpm under load with 10s1p A123. I then replaced the Neu 1512 with a Neu 1515/2Y (1100kv) geared it 1:13 or 1:12,13 with the same batteries: the motor reached 30000-31000rpm under load. Both motors peaked at 2.5KW, top speed and temperatures of all components were similar. But the feel was different. The smaller Neu 1512 seemed more responsive, spun up faster and was easyer to drive, the Neu 1515 had crazy amount of torque and wheeled the car far more often as the smaller motor. Acceleration was almost identical with both motors as the chassis and tires were the limitation. Drive time was similar too.

Higher revving motors can become difficult to gear. 11 or 12 tooth pinion is the lowest you can go. You might need a bigger spur (truggy). By choosing a higher kv 1509 gearing becomes even more crucial as lower turn motors need higher Amps to achieve the same torque level as higher turn motors. I would crunch some numbers using the very handy speed calculator and look if you can gear a high kv 1509 properly. You may also drop Mike @Rcmonster a mail and discuss which 1509 would be best suited for 4s and which gearing he would recommend.