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HelicopterMain Discussion › 10S or 12S setup better?
08-04-2013 06:22 PM  4 years agoPost 1
Flyin for Jesus

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Dana Point, Ca. 92629

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I have a TT Titan X50E I'm working on right now... I have a 630KV motor that can run up to 12S.
On 10S, I can leave the gearing stock and achieve the head speed I'm looking to run... or I can go 12S and change the gearing to still give me the same head speed.
Which one comes out better? assuming the same watt/hrs in both the 10S or 12S packs, is it better to spin the motor faster with less torque on it because of the lower gearing? Or better to spin a bit slower but more torque.
I know that loading a motor ramps up the current draw quickly but does spinning it faster eat up equally as much power?

Anyway, thanks for the help everyone.

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08-04-2013 09:22 PM  4 years agoPost 2
unclejane

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santa fe, NM, USA

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Both setups are likely going to be capable of vastly more power than you're going to need most of the time. So the 12S setup will probably be the more wasteful configuration, with more excess energy being used to spin the motor at 80 billion RPM as opposed to the mere 65 billion RPM of the 10S setup.

For example, the flight time of my Whippy E on 12S is about 8-9 minutes (unsure of the headspeed, it's around 1900), but if I pull one of the flight packs and fly it on 6S - headspeed about 1100rpm - the flight time goes up to about 11 minutes.

So the efficiency of the system is improved at the much lower speeds and available power levels. The blades run at a higher, but more efficient AOA, less power is thrown away as heat at the motor and ESC, less loss in the power train due to friction, etc.

That'd be my guess, but try them both and see what you get. And try 5S and 6S also for grins...

LS

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08-04-2013 09:40 PM  4 years agoPost 3
cudaboy_71

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sacramento, ca, u.s.

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for me it's always been about keeping the electronics, motor, and packs cool for a given headspeed. with that, ohms law says it always makes sense to go higher voltage/lower amps if the option is available.

however, with your goals, 10s may hold up just fine.

case in point--my logo 600:

i have it running a 4035-560 geared to run 2200 headspeed on 10s. i have several hundred flights on it now and the packs always come down a touch warmer than ambient. the IR of the cells is barely higher than when new. the 110amp esc logs flights in the 70-80 amp range. the governor holds hs to within 20RPM through every move i can throw at it.

for me it makes zero sense to go to 12s. there's nothing to be gained.

if it ain't broke, break it.

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08-04-2013 10:18 PM  4 years agoPost 4
Darren Lee

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Woodstock, GA

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Honestly, I don't think you are going to see much difference between the two setups. I've flown my E5s on 12S and 10S and power is virtually the same. I also used the same motor and only changed gearing.

The real consideration, IMO, is pack availability (more options for 12S) and charging setup.

Team Synergy / Rail Blades / Morgan Fuel

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08-04-2013 10:46 PM  4 years agoPost 5
Flyin for Jesus

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Dana Point, Ca. 92629

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The manual suggest 2200-2300 head speed... I won't need that so I do understand that a 1200 head speed is always going to be more efficient.

I worked this up just to figure gearing and such...

Suggested setup with the 630KV motor is 10S and 15T pinion With 135 spur gives a 9:1 ratio
37V x 630KV / 9 = 2590RPM max head speed. From my understanding, running a 2200RPM to 2300RPM puts the motor at 85% - 89% which is in its efficient range.

44.4V x 630KV / 10.385 (13T pinion) = 2693RPM max head speed
Running 2200RPM to 2300RPM puts the motor at 81% - 85%

44.4v x 630KV / 11.25 (12T pinion) = 2486RPM max head speed
Running 2200RPM to 2300RPM puts the motor at 88% - 92%

I don't know where the efficient range of the motor is... but someone once said between 80% and 90% of the max RPM.
Looks like the 13T puts the motor in the efficient range but the 12T even though runs the motor a bit faster, there is less drag based on the gear ratio.

With the 12S, I will be changing the gearing which will reduce the drag on the motor.

Point is, with the motor out of the heli and applying full voltage... motor pulls something like 2 amps. Grab the motor lightly and squeeze enough to put a little drag on it... then the amps start going up. so, will gain any efficiency with less resistance on the motor due to better gearing? or will loose efficiency by spinning the motor faster?

Does that make sense to everyone?

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08-05-2013 05:36 PM  4 years agoPost 6
rafflerback

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Willingboro, NJ

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Hey UncleJane. You just removed a 6s pack from you 12s heli and flew it. You didn't change anything else? I have a Rave 90 and a T-Rex 600 Pro that I don't fly much because changing 12 cells is a PITA. I've was thinking about converting them to 6 cells but thought I'd need to change the pinion and motor. The slower head speed isn't a problem as I don't fly 3D.

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08-05-2013 10:01 PM  4 years agoPost 7
Flyin for Jesus

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Dana Point, Ca. 92629

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I've done a fair bit of research on brushless motors and ESCs and my knowledge of electronics... I'll explain what I know and if there are any electric experts that see something wrong with my explanation... Please make corrections.

So... Power. In gasoline engines is Horsepower. Electric motors measured in watts.

Lets do the gearing part. Diesel engine 500HP at 2500RPMs puts out 400ft. Lb of torque. ( not actually figuring this number... Just making one up for demonstration purposes)
A 500HP gasoline engine peaks at 5000RPM so it's torque output would be 200ft lbs. Ignoring engine weight and the actual graph of torque in the engine.. With a gearing change... Both engines would be exactly the same. You could put a gearbox on the diesel motor gearing the output to be 5000RPM... But you would only have 200ft lbs torque.

Now the heli... It is all watts here. You can have a 1V 500 watt motor... And also have a 500v 500watt motor. The 1v motor needs 500 amps so the disadvantage of it is you need really heavy wire capable of handling 500amps. The 500v motor only requires 1amp. No huge ESC or heavy wires.

To a heli... 600 size. It takes so many watts to simply spin the blades... Higher RPM, the more watts it takes. Lets make up some numbers... Lets say it takes 250watts of power to spin 600 blades 2200RPM but only takes 150watts to spin them 1100RPM. ( both at 0 pitch ) now you just saved 100watts.
Now... Lets say at 1100RPM... It takes 500 watts to spin the blades at whatever pitch to hover... Then lose a battery and make the heli lighter... Now it only takes say 350watts to hover... More power savings.

Short story... With 1 pack... You have half the power. Like half a tank of fuel. A single 6S 3000mAh pack has 66.6 watt hours of power... Can provide 66.6 watts of power for 1 hour... Or 133.2 watts for 30 min and so on.
If you're going to cut your total power capacity... You have to cut your power consumption in half to maintain an equal flight time.

Simple sport flying, low head speed and lighter heli... Might do that job... I don't know. Just know that if you have a KV motor that runs off 12s and you cut your voltage in half... You might not be able to get a pinion to get the head speed back up... But certainly... 2200 HS on 12S would yield 1100 HS on 6S without any gear changes.

Just for warnings... Put in a single 6S and you don't cut your consumption in half... You won't get the same flight time... And you'll need to make sure you don't exceed your C rating on the batt... Or the current on the ESC.

All of this can be figured but I have to get my electric heli in the air before I can log any data and make adjustments to see the effect.

I hope this makes sense to you... Also, corrections welcome.

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08-05-2013 10:16 PM  4 years agoPost 8
Flyin for Jesus

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Dana Point, Ca. 92629

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Oh... I mentioned gearing earlier. Theoretically, you can make any motor work as long as it can handle the wattage required by the heli... Regardless of KV ( regardless assuming that the gearing possibilities are limitless... But we know they are not. My heli ranges from 11.25-1 to 7.4372-1) so your KV will need to be in range of the gearing possibilities. )

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08-05-2013 10:18 PM  4 years agoPost 9
unclejane

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santa fe, NM, USA

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Hey UncleJane. You just removed a 6s pack from you 12s heli and flew it. You didn't change anything else? I have a Rave 90 and a T-Rex 600 Pro that I don't fly much because changing 12 cells is a PITA. I've was thinking about converting them to 6 cells but thought I'd need to change the pinion and motor. The slower head speed isn't a problem as I don't fly 3D.
No, didn't touch a thing. I just took out a pack and went flying on 6S. The only thing different is because of the much lower head speed, the tail rotor has way way less authority so the tail blows out super easy.

I did't even touch the throttle curve or the gyro gains, I just fired it up and went. Nice and calm and sounds like a full scale chopper....

LS

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HelicopterMain Discussion › 10S or 12S setup better?
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