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Home✈️Aircraft🚁Helicoptere-AlignT-REX 500 › Help with RPM
04-04-2010 04:07 AM  10 years ago
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ssphoenix

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Phoenix

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Help with RPM
Hi everyone,

I need a little help with my trex 500. Got the change to fly it today and can’t seem to get the rpm up. My setup is stock align speed controller, 1100 8pole haker motor, and 5S 3000 lipos (I think they are called zippy lipo blue pack (3 different packes)). I think the trex came with two pinion gears and I used the highest one.
I’ve follow the instruction in the manual to setup the speed controller and everything went pretty well. I’ve setup 3 different throttle curves 80%, 85% and 90. Even at 100 I don’t get more then perhaps 1500-1700 rpm. I am able to hover but wobbles quite a bit.
I would greatly appreciate if anyone can shed some light. Otherwise this thing flies extremely well.

Thanks
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04-04-2010 04:17 AM  10 years ago
snjbird

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Kissimmee, Florida- USA

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Here is a link to a HS program, from my memory a 1100KV motor with 5S will be hard to gear...[url=http://www.readyheli.com/Online_Headspeed_Calculator_s/81.htm]

I ran the numbers, you will be looking to get a 22 maybe a 23 tooth.
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04-04-2010 04:40 AM  10 years ago
dkshema

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Cedar Rapids, IA

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1100 KV motor and 5S...

(5 x 3.7 Volts) X 1100 RPM/V = 18.5 x 1100 == 20,350 RPM for your motor, no load.

Assume an 80% efficiency, 20,350 X .8 = 16,280 RPM.

The kit comes with a 12 tooth and 13 tooth pinion, you say you chose the one with more teeth, that means you are using a 13 tooth pinion.

The main gear has 162 teeth. Using a 13 tooth pinion, your reduction ratio -- motor to head is 162 / 13 = 12.46:1.

Dived that 16,280 RPM at the motor by 12.46, the head will be turning 1306 RPM.

It's a wonder you can get the darn thing flying at all.

An 1100 KV motor isn't going to cut it.

You'll want something like 2600 RPM at the head to make this heli wake up and fly.

Even with an 18 tooth pinion, at 5S, you'll be turning maybe 1800 RPM. Still too low for all but maybe a hover or two.

A 6S pack, 18 tooth pinion, you'll be pushing 2200 RPM, a respectable RPM, but still a bit slow for the 500.

-----

The 500 manual has a chart showing various motor/pinion/battery combinations on page 24.

If you want to continue to use your 5S battery pack, put the STOCK motor (1600 KV) in your heli, stick a 15 tooth pinion on it, and go fly.
-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz
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04-04-2010 05:59 AM  10 years ago
ssphoenix

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Phoenix

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trex 500 rpm
Very much thanks. This make alot of sense now. I selected the hacker mainly because i was told heating should not be a problem here in phoenix. But looks like i am going back to the stock motor.

thanks much.
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