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HelicopterScale Model RC Helicopters › Motor & Voltage Questions
01-31-2018 04:24 PM  85 days agoPost 1
aja1216

rrNovice

Grand Island, NY - USA

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Hello - I want to build Vario UH-1D for T-Rex 700. I have a Scorpion 4035-450kv with YGE 120hv that I would like to use. Target HS (from what I read) sould be 1300rpms. To get that low I would need to run an 8s with a 12T Pinion or I can run a 10s with 10T Pinion (I can't find a 10T pinion anywhere).

Is it ok to run with an 8s setup on this size heli or should I go find a lower kv motor?

Thanks,

AJ

PS - I got the number by using MrMel's Headspeed Calculator

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01-31-2018 04:42 PM  85 days agoPost 2
ssmith512

rrKey Veteran

Indianapolis, IN USA

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I would not run 8S. 10S might be OK, depending on how heavy your model ends up being (how much scale detail you put into it). I personally would run 12S and find the appropriate kV motor.

I am building a Vario BO-105 for Trex 700 and am running 12S with an Xnova 300kV motor at 1200rpm (4 blade head). It flies very nicely and everything stays pretty cool.

Steve

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01-31-2018 05:26 PM  85 days agoPost 3
Wemo

rrApprentice

Hampton Roads, VA

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delete
delete

"How high do they go? Are those things hard too fly? How much do they cost?

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01-31-2018 08:23 PM  85 days agoPost 4
Flyin for Jesus

rrVeteran

Troy, IL. 62294

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nothing wrong with running 8s or 10s in that heli. People in the LHS sub-forum run their 700s with 6s.
If you do get a lower Kv motor and run higher voltage, you pull less amperage so you can get away with a smaller ESC.

I personally run the highest voltage I can do for almost all my helis. But I also try to share as many packs as I can between helis so I don't need to have $3k worth of packs in my garage.

Looks like in your case, if keeping your motor, 8s is what you're looking for since you cannot find a 10T pinion.

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02-01-2018 08:21 AM  84 days agoPost 5
Andy01

rrApprentice

Brisbane, Australia

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Could you run a Mod 0.7 Trex 700 main gear ? From memory it is about 164T. Run it with a 13T pinion.

I use one in my 600 sized Seahawk that runs 4x 600mm blades at 1350rpm, 4x 105mm tail blades, weighs about 19 lbs. I run a Xera 4030-470kV motor on 12s with a CC Ice 2 80HV ESC.

RPM = 450kV x 44.4V x 0.9 x 13T / 164T = 1425rpm at 100% towards the end of a flight. Governing to 1300rpm would be 91% which is about spot on.

Colin

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )

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02-01-2018 12:31 PM  84 days agoPost 6
aja1216

rrNovice

Grand Island, NY - USA

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Thanks Everyone - decide to run at a higher voltage.
Andy01
Could you run a Mod 0.7 Trex 700 main gear ? From memory it is about 164T. Run it with a 13T pinion.
Thanks Colin for the option
Flyin for Jesus
I personally run the highest voltage I can do for almost all my helis. But I also try to share as many packs as I can between helis so I don't need to have $3k worth of packs in my garage.
Excellent point on sharing packs!
ssmith512
I am building a Vario BO-105 for Trex 700 and am running 12S with an Xnova 300kV motor at 1200rpm (4 blade head). It flies very nicely and everything stays pretty cool.
Saw your build thread on this heli. Love the SSSFR method I'll definitely be using it.

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