pinions and head speed?

[audio131]

hi, kit comes with a 15t pinion. im planning on using the align mx wotor that comes on the pro kit. 510kv. using this motor and the 15t pinion on 12s. head speed is about 100 rpm less than the gear ratio on the t600 pro. which is high. about2500 average. the x50 on 10 withthe 15t is like close to 2100. so will 2500 be way too high for this heli and its tail gear ratio or am i ok or should run a lower pinion?

[ranma103]

Depends on the head speed you want i'm useing the align 510kv motor with the stock pinion on 10s it depends as well on what batterys you want 10s or 12s..

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[audio131]

hi. im using the 510k align 12s motor too. will start out using the 15t pinion on 12s and see if its too much for this heli or not.im thinking its perfect gear ratio and not much strain on esc. as long as the x50e tail can handle it.

[KouDy]

You can calculate your headspeed from battery voltage and ratio between pinion and main gear. It's explained here : https://www.helifreak.com/showpost.p...2&postcount=54

Fairly simple equation just put in your numbers...
12s battery - 3.7 x 12 = 44.4V
510kV motor 100% RPM : 510 x 44.4V = 22644 RPM

n1 = ( 15 / 85 ) x 22644
n1 = 3996 RPM on the main gear...

If you want 2500RPM on head then :
2500/3996 = 0.62 => 62% throttle

Similarly for 2100RPM you would go :
2100/3996 = 0.52 => 52% throttle

Of course friction is not counted, resistance of the air, etc...

EDIT : Number of teeth on main gear (85) i considered nitro version of X50, i don't think they have separated main gear for them...

[gwright]

electric version maingear is 135 tooth, not 85.

I'm using a 580KV hacker on 10S. spinning it too fast at the moment at 2350, but with the ESC I'm using I can't easily go much lower unless I change pinions. This particular ESC governer works extremely well,.. when throttle percentage is above 85-ish,.. but there is some quirk in the software and when you run much lower on the percentage it doesn't govern very well. Currently using 15 tooth pinion.

A side note, when computing possible headspeeds with gearing/KV/battery, the ESC and specifically the timing in the ESC, will greatly affect the end result. You raise/lower the effective KV of the motor when you raise/lower the timing. Do I use a calculator and the gear/batt/kv number,.. heck yes,.. initially, then I almost always find out that the real world number are higher,..sometimes far higher, than the calculator told me they'd be <G>. This is just something to keep in mind. Since I don't need much headroom for my style of flying and the ESC's I run I try to initially select a motor/pinion that is only capable of the highest rpm I want to run, knowing that with timing sufficiently advanced to make the motor happy, the kv will be a bit higher and I will have the headroom that I need (100 or so rpms) without having an overgeared and innefficient setup.
An example is one of my G4's, I'm using 12S, 400KV motor, 12 pinion, but with timing at 20 degrees advanced, where the turnado motor is very happy. This computes to 1920 possible {(44.4*400*12)/111} . My three flight modes currently set at 1600/1750/2000. The 2000 rpm mode has some headroom also,.. as at full throttle in hover I can get to just shy of 2100.
The ESC Im using in the X50 does not have specific numbered timing advance settings,.. simply "ranges". In the highest timing mode which I'm using, at full throttle it will do almost 2500. I'm using 2350 in my highest rpm flight mode which gives me just the right amount of headroom for my style of flying, plus a tiny bit. The math works out to 2384 possible.

[ranma103]

thanx for the info gary the esc i'm planing to run has no governor i was planing to use a phase sensor with the vbar governor.

[audio131]

i dont fly using govs.i know the new stuff is supposed to be great. but with the power of these helis i find 100% throttle flat line works fine for me.. head speed this way will get you around 2500 mid flight 15t pinion on 12s..

[what-d-heli]

Ok, using Mr. Mel's HS calculator in Ready Heli. I got this result....

25C 12 Lipo, 135t MG, 15t PG, Governed (Jive), 90% eff. Extended Result and ATV Adjusted:

Throttle 60%: 2064
Throttle 65%: 2127
Throttle 70%: 2191
Throttle 75%: 2255
Throttle 80%: 2318
Throttle 85%: 2382
Throttle 90%: 2446
Throttle 95%: 2509


I just maidened my X50E today and had my IU1 set at 60 flat and IU2 at 65 flat. My buddy has his iphone HS app and have him check my HS. He got...

IU1 somewhere 2050 and IU2 around 2100

Running my ESC at KSA mode.

I use only 1 IU in all my flying and I will be sticking with IU2. Enough HS for the flying capability that I have for now.