RunRyder RC
WATCH
 1 page 4885 views POST REPLY
HomeAircraftHelicopterMain Discussion › RPM ratio and pole count settings
10-27-2012 04:54 PM  5 years agoPost 1
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

I am trying to setup my Aircraft Telemetry Brushless RPM Sensor for my Trex 550 V1 using a DX7S. There are settings for the 'pole count' and 'ratio'. Does anyone know what these settings need to be or where I could find any information on how to obtain these values? I am trying to get my head speed. The folks at my LHS looked at me like I have two heads when I asked them for the specifics

TIA,
Andy

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 05:03 PM  5 years agoPost 2
wrongler

rrProfessor

Brewerton, New York

My Posts: All  Forum  Topic

Usually you can find that info if you goggle the motor specs.

Bill Whittaker

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 05:04 PM  5 years agoPost 3
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

Pole count is the number of magnets in your motor.

Ratio would be the main gear to pinion ratio (number of teeth on main gear divided by number of teeth on pinion).

If you have 100 tooth main gear, and a 10 tooth pinion, the gear ratio is 10:1

A quick way to calculate your head speed:

((motor Kv X battery voltage) x .85) / gear ratio

Assume your main gear has 170 teeth, and you are using a 16 tooth pinion, and are running a 1220 Kv motor with a 6S battery pack.

Gear ratio = 170 / 16 = 10.625

A 6S battery pack has a nominal 22.2 volt output.

((1220 x 22.2) * .85) / 10.625 = 2166 RPM.

The "0.85" number is there as an assumption that your system is 85% efficient.

-----

The 600M motor is a 6-pole, 1220 Kv motor.
The 600MX motor is also a 6-pole, 1220 Kv motor.

There are 510 Kv versions, those are for other than 6S operation.

-----
Dave

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

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 06:19 PM  5 years agoPost 4
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

Tank you for the help. I am using the RCM-BL600MX which is a 6 pole motor according to your specs.

Main Gear = 170T
Pinion = 16T

In the Align manual or on the back of the manual the Drive Gear Ratio is listed as 1:10.62:4.5

What is the 4.5? The reason I ask is that in the TX setup menu I have the ratio setting which is below:

2.00:1

I can edit the '2' value and the '00' value but cannot edit the last value or the '1'.

I plan on using 10.62 and was thinking that I need to set the last value to 4.5. Is this correct?

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 07:21 PM  5 years agoPost 5
TheWoodCrafter

rrKey Veteran

Costa Mesa, Ca.

My Posts: All  Forum  Topic

Pole count is the number of magnets in your motor.
I thought it was the number of poles on the armature.
Not the number of magnets on the stator.

Thanks, TheWoodCrafter

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 08:44 PM  5 years agoPost 6
red_z06

rrProfessor

Dumont, NJ

My Posts: All  Forum  Topic

I thought it was the number of poles on the armature.
Not the number of magnets on the stator.
That would be called stator teeth count.

Here is my motor design with 40 poles and 36 stator teeth. While magnet poles can be any number, stator teeth count for 3 phase brushless motors run multiples of 3.

www.JustinJee.com

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
10-27-2012 09:34 PM  5 years agoPost 7
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

I just went through a few battery packs and my max head speed was 2300 RPM with a throttle curve of 0-75-80-85-90 which I know I need to adjust. Does this RPM number sound correct? I am still learning as I go

I set the pole count to 6 and the ratio to 10.62.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 09:37 PM  5 years agoPost 8
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

The number of poles in this context refers to the number of MAGNETIC poles, not the number of stator poles or "teeth".

Counting the number of magnets usually works, but in some cases manufacturers may use more magnets to improve performance...

A four-pole motor would have four magnets arranged around the rotor as N-S-N-S. But they could also double up the magnets NN-SS--NN-SS. There are 8 magnets, but only four poles.

-----
Dave

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

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2012 09:37 PM  5 years agoPost 9
Dr.Don

rrVeteran

Cedar Park, TX -- USA

My Posts: All  Forum  Topic

4.5 is the tail ratio and has nothing to do with what you are setting. Your ratio is 10.62 based upon the 170 main and the 16 pinion.

FYI, the tail ratio is the number of revolutions of the tail rotor for each revolution of the head.

Dr.Don

PM  EMAIL  GALLERY  Attn:RR  Quote
10-28-2012 03:47 PM  5 years agoPost 10
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

Here is my motor design with 40 poles and 36 stator teeth. While magnet poles can be any number, stator teeth count for 3 phase brushless motors run multiples of 3.
Very Nice....

Any advice on head speeds? My max head speed is 2300 RPM with a throttle curve of 0-75-80-85-90. Is this a good speed? I would like to use a lower curve if doing so gives me more battery life with no adverse affect. It's not that big of deal because the helicopter flies great.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-28-2012 03:56 PM  5 years agoPost 11
red_z06

rrProfessor

Dumont, NJ

My Posts: All  Forum  Topic

RPM will vary greatly depending on the types of maneuver you intend to perform.

10% reduction in head speed will give you greater than 20% flight time gain.

For hovering practice, even 1800-2000 will be more than sufficient. With higher head speed it will be a bit more stable in the strong wind but that is about it.

With FB, you lose control sensitivity with lower head speed due to the FB acting like a mechanical gyro. But with FBL, that is not true either. So, there is really no negative for lowering the head speed. However, best way to lower the head speed is not with the ESC but with the pinion.

www.JustinJee.com

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
10-28-2012 04:52 PM  5 years agoPost 12
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

Thank you red_z06.
However, best way to lower the head speed is not with the ESC but with the pinion
I was hoping to use my esc or throttle curve to adjust the speed but I keep hearing that it is a bad idea. Doing so would prevent me from having to change gears etc. Why is it a bad idea to adjust the esc?

PM  EMAIL  GALLERY  Attn:RR  Quote
10-28-2012 05:11 PM  5 years agoPost 13
red_z06

rrProfessor

Dumont, NJ

My Posts: All  Forum  Topic

With or without the gov, ESC controls motor speed by chopping the commutation pulse.

Full would be solid DC current while that teeth is energized. To slow it down, ESC performs this by chopping it into pieces by turning it on and off many many times (PWM frequency). As such, practical limit is reached (without much efficiency loss) at around 70%. So, below this 70% much more power is lost to deliver the lower speed.

Since more current is being dumped than needed, the excess goes to heating the ESC.

This is why during the early days of Align 600 that more novice hovering at lower head speed had ESC fires than the people who were stick banging at 100% throttle.

www.JustinJee.com

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
10-28-2012 05:15 PM  5 years agoPost 14
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

I am using a 16T pinion gear. What sizes would you suggest? They are inexpensive so I could get a few of them.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-28-2012 05:38 PM  5 years agoPost 15
red_z06

rrProfessor

Dumont, NJ

My Posts: All  Forum  Topic

What is your immediate goal/use for this heli?

www.JustinJee.com

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
10-28-2012 06:30 PM  5 years agoPost 16
HeliNutAndy

rrKey Veteran

worcester, MA USA

My Posts: All  Forum  Topic

I started flying six months ago and my main goal is to sport fly. Circuits, a flip or two, maybe a loop I already get over ten minutes of flight time using a 5000MAH battery and could use some more time. I also like the sound of the main blades (chop,chop,chop) and would like some more chop if that's possible by lowering the speed My ultimate goal is to become the best pilot I can and to learn as much as I can.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-28-2012 09:03 PM  5 years agoPost 17
icanfly

rrElite Veteran

ontario

My Posts: All  Forum  Topic

good info on esc's here.
lowering the speed
pinion change is best. A brushless mo works best at about 90 percent and drag from the machine will lower that rate a bit.

nice bl motor red zo6, watsit for?

PM  EMAIL  GALLERY  Attn:RR  Quote
10-29-2012 11:47 AM  5 years agoPost 18
red_z06

rrProfessor

Dumont, NJ

My Posts: All  Forum  Topic

You will do fine with 15T pinion. You will also save unnecessary juice waste by not using the gov mode. Your ESC will also run cooler.

We normally fly at 100 90 100 or similar on idle up 2. But, if you like a bit more consistent rpm, you can fly mostly in idle up 1 at 10% less than idle up 2.

www.JustinJee.com

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 1 page 4885 views POST REPLY
HomeAircraftHelicopterMain Discussion › RPM ratio and pole count settings
 Print TOPIC  Make Suggestion 

 7  Topic Subscribe

Tuesday, August 14 - 10:25 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online