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[doug5166]

Hi , I'm thinking of getting myself an ec145 (600) from rca, I have a hk600gt for the mechanics, and numerous 6 cell 5000 batteries. After spending days looking through old posts its time to ask questions.

I will be using a 4 bladed head so thinking 12s is the way to go, which means upgrading the motor (align 700mx 460kv or 500kv). I hope to keep the 170 main gear so would I be right in thinking that the kv motors above with a 13 tooth will get me in the region of 1400hs?.
Upgrade the esc to cc ice hv 80 or another recommended esc?.

Iv also read in some posts about the 45 degree tail rotor(black elbow) not being up to the job, I know sm do an upgraded one, is this any better?.

Thanks in advance.
Doug

[npomeroy]

12S @ 4.2V/cell = 50V
50 x 500 kv = 25000 motor rpm
170 / 13 = 13:1 reduction
!00% power and 100% efficiency = 25000/13 = 1923 rpm
say 80% output = about 1500 rpm

[Andy01]

RPM = 460kV x 44.4V x 0.9 (efficiency) x 13T /170T = 1405rpm at 100% throttle towards the end of a flight.

This means that your max governed headspeed would be 1405 x 0.95 = 1335rpm, so it would be better to use a 14T pinion, or 164T main gear. Ideally you want to be between 90 and 95% governed speed to be kind to the ESC.

I have an RCA 600 sized Seahawk with 4 blade head & tail, use 12s, 470kV Xera motor, 164T Mod 0.7 Trex 700 main gear and 13T, with a CC Ice 2 80HV. Heli weighs 8kg/17½lbs, and flies well at 1350rpm.

And no, in my experience, the supplied black plastic angled gearbox is NOT up to the job - mine failed during the first hover as a pod and boom. The SmartModel kit is much better, although I upgraded mine to use Align gears.

Colin

[doug5166]

Thanks for the replies, colin, if I change main gear ratio, do I need to change the autorotation ratio too?

[Andy01]

I am not aware of many options for gearing on the auto gear.

Sometimes tail authority can be an issue when slowing the headspeed because the tail slows as well. This can usually be overcome by either fitting more tail blades (eg. 3 or 4 blade rotor) or longer/wider blades.

Colin

[doug5166]

Thanks for your help colin.