You can use which ever one you want, they will just use different sized props. If you want to stick to the stock sized props, go with the 1100kv 'C' motor. The other motors spin at a higher speed, so they will take smaller props. Just remember that with smaller props that spin faster, having the props balanced becomes more important.
Hey Dillz - Do you think there would be much difference between the 1100kv and the 1300kv swinging a stock 9x6 LP prop? kv being rpm per volt supplied right? Just having a bit o' trouble justifying double the cost for the slower motor At this point I am more concerned with more thrust/torque vs top end speed for the cub
Last Edit: Jul 6, 2010 21:01:11 GMT 1 by greedyg76
If it aint broke.... you haven't let me have a go at it....
I just looked on drivecalc, a computer program that can predict such things, but the standard Turnigy 35-36 motor isn't on there. I can see how the stock 9x6 prop goes on the 1100kv 35-30 motor though. Drivecalc is free so you can download it yourself and have a fiddle if you like.
According to drivecalc, the stock 9x6 will only draw 12 amps with the 1100kv motor, so once you dial it up to the 1300kv on a slightly larger motor it should be just about right. Just beware though that this is more of a 'best guess' than a guarantee. Without your own wattmeter it can be difficult to be sure.
I suppose the best way you can test it yourself without a wattmeter is to bench test it by running the motor at WOT with that prop for a minute, then seeing how hot the motor is. If the motor is too hot to keep your hand on it then you're probably working it too hard.
I use a 10x5 APCe on a 35-36 1100Kv in my Gem. Others use up to a 12 x 6 on the same motor which would suggest that the HZ prop will probably be OK on the 1300Kv version as far as motor power draw is concerned. One thing you may want to consider is that the HZ props are not the best, and are rated to a relative low RPM rate when compared to OEM makes ( e.g. 9x6 APCe is listed in DriveCalc as max rpm of 21100, HZ 9x6 is listed at only 11000rpm). What does this mean?? Well, a motor with a Kv of 1300 will spin at 13000 rpm @ 10 V, the number will be much higher on a fresh (good) Lipo pack. How will this affect that prop? Your guess is as good as mine. The numbers suggest that it is out of it's specificaton so may well throw a blade at WOT. This will unbalance the motor/prop dramatically, possibly making the aircraft unflyable. You also have a chunk of plastic (the thrown blade) being ejected at a fair rate of knots. It may even be worse that that in that the whole prop disintegrates. I know that I wouldn't want to be anywhere near that when you spin it up.
TBH, if you want to go with that motor to save a few $, fine and dandy, but look at fitting the right prop for it, rather than saving next to nothing by reusing the (inferior IMHO) HZ props. FWIW, I consider the 35-36 too big a motor for the SC anyway. 200-250W is more than enough for the airframe, so you could make savings elsewhere by selecting a slightly smaller motor (35-30 1100Kv/ 28-36 1000Kv??). I still wouldn't use the stock prop though.