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HelicopterMain Discussion › What is more efficient ?
04-09-2011 02:57 PM  6 years agoPost 1
mcfast

rrKey Veteran

Quebec Quebec Canada

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Hight KV and a hight gear ratio {like 20/1}
or a low KV and a low gear ratio {like 15/1}

P.S. sorry for the spelling or the grammar I am dyslexic!

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04-09-2011 03:31 PM  6 years agoPost 2
Justin Stuart (RIP)

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Plano, Texas

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red_z06 once gave me the engineering specs to say (if I remember right) that the efficiency is the same.

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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04-09-2011 04:18 PM  6 years agoPost 3
Rogman88

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West Monroe, LA

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A plus for lower kv and higher cell count(with gear ratio as described above) is amperage through the system is lower thus easier on the system. This is why many people are getting away from 6S Trex 600's and going with 8S, 10S and my favorite the 12S. Yes you can fly with 6S, but batteries last longer and things run cooler on more cells and lower kv.

High Voltage just works better

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04-09-2011 05:27 PM  6 years agoPost 4
Solmanbandit

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Tucson , AZ

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More cells can be only part of the equation. The C rating has a big effect on how efficient it runs as well. I know that there are guys who run 6S on a 450 here on the forum, but I don't see the need. Run a 30 or 40C on up and you will get very good performance. I use to run 20C battery and it would get very hot and batteries wouldn't last long. I switched to 30C and I have more power and everything runs much cooler.

Trex 700E / Trex 500 ESP - Ikon/ HD 500 - Ikon 2/ Goblin 500 Ikon 2

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04-09-2011 06:39 PM  6 years agoPost 5
mcfast

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Quebec Quebec Canada

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I was just thinking which was better, at same head speed and same S
Looking in bilding a complet Scale 500 size MD500E.
What would be a good head speed for a scale 5 blade head ? and what blade size ? I think going to S8 would be good.

Thanks

P.S. sorry for the spelling or the grammar I am dyslexic!

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04-09-2011 07:08 PM  6 years agoPost 6
CX1

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Canada

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since it is going in a scale (heavier bird) go with a higher gear ratio than stock
if it was 8:1 then maybe 9:1 would give you more torque to carry the fuse

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04-09-2011 07:21 PM  6 years agoPost 7
MartyH

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USA

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Higher KV and higher ratio for a scale application is my choice.

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04-09-2011 10:35 PM  6 years agoPost 8
AirWolfRC

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42½ N, 83½ W

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For the same wire gage and same power, higher KV and higher gear ratio is better.

The efficiency losses come from heating up the wiring (motor included) with the high currents.

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04-10-2011 12:51 AM  6 years agoPost 9
Solmanbandit

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Tucson , AZ

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I think you might have the gear ratio thing mixed up. Typically when you go higher KV motor, you go with a smaller gear.

Trex 700E / Trex 500 ESP - Ikon/ HD 500 - Ikon 2/ Goblin 500 Ikon 2

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04-10-2011 01:08 AM  6 years agoPost 10
fung_jeff

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Vancouver, BC, Canada

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More cells can be only part of the equation. The C rating has a big effect on how efficient it runs as well. I know that there are guys who run 6S on a 450 here on the forum, but I don't see the need. Run a 30 or 40C on up and you will get very good performance. I use to run 20C battery and it would get very hot and batteries wouldn't last long. I switched to 30C and I have more power and everything runs much cooler.
Running a higher C battery on a heli with low amp draws have nothing to do with power. A battery can deliver 200a's continuous, but is it going to let 200a's out right away if the application isn't asking for it? As for your situation, YOUR power system was drawing more than your battery could let out so it got hot. Once you added the higher discharge rate LiPo, it became cool because of the increased amount of amps the battery could let out.

Jeffrey Fung...15 Years old - FLEET: Evo 50, Raptor 30, Trex 500, SDX's, X-Spec, Logo 10/400

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04-10-2011 01:37 AM  6 years agoPost 11
Rotowerkz

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Windham, NH

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Efficiency of any electric setup really boils down to how much energy is being dissipated as heat. You want to minimize the resistive losses. How do you do this? You decrease the gauge of copper windings in the motor, and use fewer turns. This also tends to force the kV down, making it necessary to use a higher voltage setup to get the same motor speed.

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04-10-2011 02:28 AM  6 years agoPost 12
BladeStrikes

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Shelby TWP,Mi

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Im useing a CC ICE100 ESC,1500KV motor with 14T pinion on 6 cell's and it's 100% efficent..Butt load of power too .Motor,esc and pack's don't get hot..

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04-10-2011 02:40 AM  6 years agoPost 13
Santiago P

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South West, Ohio

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The efficiency losses come from heating up the wiring (motor included) with the high currents.
That is correct.

There are also machanical losses (friction) and the worst one, the aerodynamic losses from the symetrical crappy blades we use.

If this is a scale application, get a set of semisymtrical OR flat bottom blades, the lifting will go up between 20 to 40% better with the same power consumption. that means 20% to 40% longer flights.

Santiago

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04-10-2011 02:51 AM  6 years agoPost 14
Solmanbandit

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Tucson , AZ

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Im useing a CC ICE100 ESC,1500KV motor with 14T pinion on 6 cell's and it's 100% efficent
That is incorrect, you can not have 100% efficiency. You will also lose some energy thru drag and your gear train.

Trex 700E / Trex 500 ESP - Ikon/ HD 500 - Ikon 2/ Goblin 500 Ikon 2

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04-10-2011 04:18 AM  6 years agoPost 15
Santiago P

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South West, Ohio

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Yep, you just cannot get 100% on the motor-esc side. There are friction and thermal loses on the motor as well as thermal losses on the ESC.

Still the easiest place to gain efficiency is in the blades.

S

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04-10-2011 04:27 AM  6 years agoPost 16
BladeStrikes

rrElite Veteran

Shelby TWP,Mi

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Solmanbandit
Im useing a CC ICE100 ESC,1500KV motor with 14T pinion on 6 cell's and it's 100% efficent
That is incorrect, you can not have 100% efficiency. You will also lose some energy thru drag and your gear train.

Pushing it to the next level and what that is? No idea!
It sure does feel 100% efficient.I get no power loss through a 4 min flight beating on it.

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04-10-2011 04:40 AM  6 years agoPost 17
GetToDaChopper

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Las Vegas , NV

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I think you might have the gear ratio thing mixed up. Typically when you go higher KV motor, you go with a smaller gear.
+1 !

    ▲
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▲ ▲ ▲ One of a Kind !!!

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04-10-2011 12:57 PM  6 years agoPost 18
CX1

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Canada

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MartyH
Higher KV and higher ratio for a scale application is my choice.
Solmanbandit I think you might have the gear ratio thing mixed up. Typically when you go higher KV motor, you go with a smaller gear.
a "smaller gear/pinion gear" would make the gear ratio higher
you are both correct but saying it differant

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04-10-2011 04:17 PM  6 years agoPost 19
AirWolfRC

rrProfessor

42½ N, 83½ W

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I think you might have the gear ratio thing mixed up. Typically when you go higher KV motor, you go with a smaller gear.
A smaller pinion, yes, but a larger gear ratio. . . because your motor will be turning faster for the same voltage.
You want to minimize the resistive losses. How do you do this? You decrease the gauge of copper windings in the motor, and use fewer turns. This also tends to force the kV down, making it necessary to use a higher voltage setup to get the same motor speed.
Decreasing the gage means using heavier wire. That menans less turns which means higher KV, not lower.

KV = RPM per Volt
With a higher KV, you get more RPM for the same voltage.
Higher KV motors tend to have heavier wire and pull higher current than lower KV motors built in the same frame.

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