Brushless Motor ratings and timing...???

Hi Guys,

Can any of you tell me, how to rate a motor ..??? based on ..?? I am now trying to find a proper BL Motor for my new Home made Zagi...and I kinda struggling to find which motor suits best..I mean interms of KV's, Prop size ... etc...etc...etc..

I'm currently running a 43" span home made zagi with a 12" root chord, 13" sweep back with a 6" tip...running on unknow heli motor ...assumed to be X Walkera motor, and a 4.75 x 4.75 APC prop...on Lipo 11.1v 2200mah, 25c...Emax..!!

Flying was good, but once i got the hang of it....the zagi seems like ..kindaaaa lack of POWER...need more speeddddd...!!!!!! I like it to be more on 1/2 stick...but yet there is no power for the big loop...

Can anyone tell me what motor / Prop should i get from LHS....to get more out of it , in simple word The Big Fun....!!!!

Happy landing all......
Atan_126

Atan,

What you should be looking out for would be the motor KV's which will translate to the maximum prop size you can drive. Typically, for a 48" Zagi application, you should be looking to drive between 4.75x4.75 being the smallest and larger ones upto 6x4. Small props dont have good static thrust which can make launching difficult, but have better top end speed as it unloads in the air (catapult or bungee launch) Larger ones will fly out of your hands but have problem with torque roll due to the greater rotating mass so you need to correct aileron if you accelerate or throttle up.

Our favourite combos are generally outrunner/ inrunner of between 3000kv - 3800kv (3-4 turns) with the APC 4.75 square pusher prop. Most of the time these motors need about 20-30A so on the safe side, it is advisable to run 35A to 40A ESC. Make sure that you Li-Pos have the correct discharge rating as well. If you are to run 40A safely, i suggest any of the 20-25C 2000mah batteries as a minimum otherwise they will overheat and bloat very quickly!

Some proven well known combo's which i've tried before....

ALIGN 430L/XL, 35A ESC, 4.75x4.75 (good for 48" WS)
HET Typhoon 2W20, 45A ESC, 4.1x4.1 (good for 24" to 30" WS)
MEGA 16/15/3, 35A ESC, 5x5 (good for 48" WS)
HiModel 450TH, 35A ESC, 4.1x4.1 (good for 24" to 30" WS)

I believe there are plenty new generation outrunners which are excellent performers.... as compared to some of the hotter inrunners. Just try to keep within the KV range mentioned. The higher the KV the smaller the prop. Suggest that you also use an ammeter to measure loaded current throughput to ensure not burning up your ESC's due to high amp draw. To test and see if your prop is too big for your motor, you run it briefly and see if it gets hot. If it is matched correctly it will just be warm. Its always safe to start with the smaller size props first and then step up.

Hope this helps... and good luck on your testing.....

Hi Bro.... I think i got it right, since you mentioned that the motor should be just about Warm...

I flew around at the padang in Seria right behind my house, it is good but still need a bit more power for the fun,

I think by experimenting with diffrent sizes of prop will do the trick, while keeping the motor just nice to touch after the fun ends...

Thanks again,

Put it this way, faster speeds warrants for higher RPM's from your prop, so logically it would be to go smaller with higher pitch (or a square prop) and higher KV's on the motor. I assume you have a 3500kv motor since u mentioned it was a helicopter motor. Try with APC 4.1x4.1. It should unload faster in the air, but you may lose static thrust so launching can be difficult if your zagi is heavy. It also depends on how much loading your wings poses. If you built an efficient air foil, then it would make it more slippery, which means more speed but less stable and lift at low speeds. If the wing is fat, then it will drag more but gives you good lift and glide.

Its all about balancing between AUW, Prop Size, Wing Loading.

Share with us how it all goes together.

you want fast zagi try meaga motor 16/15/3+ phoenix esc 45A + prop 5*5 from grauner.+ kong battery 25c2200mAh

now I use this power set my zagi quite fast, and cannot look down becareful.

motor I order from www.hobby-lobby.com

have a nice fast flying your zagi

padsakorn