Looking to build my first motor...

[Argyle]

I figured for a beginner, the GBv™ 22.7mm Outrunner Kit from www.gobrushless.com might be a good practice motor, and if I dont screw it up, I can replace the gearbox Fiegao on my Pico Tiger Moth.

I assume on 2 cell 700-900mah this motor can haul the TM around at reasonable speeds? AUW is under 8 OZ.

[galloping gimp]

This should work fine -- a good choice for the Pico Tiger Moth. Try 17-20 turns with Wye termination and a GWS 8x4 prop.

- Jeff

[Argyle]

Thanks for the advice Jeff...the winds and termination are a bit beyond me at this point.

[Argyle]

Can I anticipate 8+ oz thrust on 2 cells?

[helifrek]

could you clue me in as to what wye termination is? I am a bit of a begginer myself. thanks.

Brandon

[ecologito]

Heli, here is exactly what are the termination options:

http://www.rcgroups.com/forums/showpost.php?p=4768726&postcount=10

http://www.rcgroups.com/forums/showpost.php?p=4771243&postcount=12

Exactly what that means,

Good luck

[galloping gimp]

Can I anticipate 8+ oz thrust on 2 cells?
I'm not sure you'll quite reach 8 oz. of thrust on 2 cells. I don't have much experience with 2-cell lipos.

However, you don't need anywhere near 8 oz. of thrust to fly the Pico Tiger Moth. The stock power system for the TM produces only around 4 oz. of thrust; your brushless system will produce much more than that!

There is good information about winding and terminations in the GoBrushless GBv Tutorial PDF (http://www.gobrushless.com/GBL_single_v2.pdf).

- Jeff

[olmod]

I would go along with the 17t,
here is a one of my builds.
GB 22mm stator
12 5x5x1 n50 17t .5 xY
no load 11500rpm@7.5v

GWShd 7035 10000rpm@3amps =7.3oz thrust.

APCe 7x5 8000 rpm@5.5amps =300g=10.7oz.

APCe 8x6 6500rpm@7.75amps=380g=13.5oz.

so depending on what prop you want to run it should be ok :)

[Argyle]

I like enough power to climb out vertically on that lil bird.

[ryanl2006]

I would try a 17turn like olmod said, and maybe a GWS 8x4 HD prop.

[helifrek]

thanks ecologito, I guess another name for wye would be star? or is that something else? I know what the stator is but what are the different types of stators? I seen triple but what other ones are there? I know these are very newbie questions but everyone has to start somewhere. I will try to post a picture of the motor I made, looks great can't wait to put some magnets in it. thanks again.

Brandon

[galloping gimp]

Hi Brandon-

Yes, wye and star terminations are the same thing.

Single, double, and triple stators refer to the thickness of the stator. The starting point is the single stator offered by vendors such as GoBrushless.com. If you stack two of them together, you have a double stator. Stacking three of them gives you a triple stator.

A thicker stator allows you to make a powerful motor. Of course, if you have a thicker stator, you must also have a deeper can and longer magnets to take advantage of the additional stator thickness.

- Jeff

[helifrek]

thanks for the great information. thats what I'm looking for is simple straight forward info with explanations for the differences. so I am guessing there are 3 different types of stators? what are the individual "arms" on the stators called? and are there always 9 of them? I seen 3 on a brushed motor. my motor has 10turns not sure what thickness but it was hard to get 10 turns. not sure about stator either, do you know where I could find some examples of a single double and triple stator? thanks again.

Brandon

[galloping gimp]

Hi Brandon-

Below is a photo of four different stators: a single, a double, a "2.5," and a triple. These are all comprised of 22.7mm diameter stators from GoBrushless.com.

The single is self explanatory -- just one stator by itself.

The double and triple are just as they sound -- two or three stators stacked together and used as if they are one thicker stator. Note that you can leave the white plastic insulation in place between the stators when you stack them. This practice is known as stacking the stators "with cheese." That is the same as saying "with insulation."

The "2.5" is a stator made from two full stators plus half the laminations of a third stator. The insulation has been removed between the stator sections, so this stator is "without cheese."

A "2.5 without cheese" just happens to be 10mm thick, which is the length of readily available magnets. Having the stator thickness the same as the magnet length makes the motor a bit more efficient, as does removing the plastic insulation between stator segments.

Commercial motors often do not use the "single, double, triple" terminology. Their stators are manufactured to the desired thickness from the start. We home builders don't have that luxury, so we stack what's available to us until we have the thickness we want.

The individual stator arms are usually called "teeth" or "slots." Do not call them "poles." That terminology refers to the magnets. (Even some vendors of motors and components refer to stator "poles," but this creates confusion.) The most common homemade motors have 9 stator teeth and 12 magnet poles.

Other numbers of stator teeth can also be used. 6, 12, and 18 teeth are fairly common. The number of stator teeth will always be a multiple of 3, assuming you want to use a common brushless speed controller.

Other numbers of magnet poles (other than 12) can also be used. Here's a table (http://www.powerditto.de/Kombinationstabelle2.html) showing possible combinations of stator teeth and magnet poles and the winding scheme for each.

I hope this info is helpful.

- Jeff

[ki0qm]

What he said.

Nice post Jeff. I've never done a 1/2 of a stator. What are you using to get the thickness down?

[galloping gimp]

Nice post Jeff. I've never done a 1/2 of a stator. What are you using to get the thickness down?
Stators are comprised of many thin laminations of metal. To make two half-thickness stators, you first completely remove the plastic insulation from a stator, then use an Xacto knife or razor blade to carefully split it down the middle of the laminations. They fall apart easily, and you end up with two half-thickness stators.

Each half-thickness stator can then be sandwiched between two regular stators to make a "2.5" stator. You remove the plastic insulation from one side of each of the regular stators so that when you stack the three parts (two full and one half-thickness), you have a "2.5" stator without any insulation between the three parts.

- Jeff

[helifrek]

thanks again Jeff, I think I am getting the hang of this. by looking at that table I could use the 3tooth stator with 2 or four magnets successfully. not that I would need one... :) I took apart another cd drive to scavenge a motor, it already had bearings, can and stator weren't as tall as the other but had a larger diameter, I wound it with 9 turns of the same wire. gearing will be 10:1 on a FP piccolo with a 2S lipo. hopefully this will work. do you think this is a good combination for my application? I shouldn't need a Kv of more than 2000. I think I am getting a bit ahead of myself :) how do I determine what kind of motor I need for different applications? like a shock flyer to a piccolo? and do people make larger cd-rom motors? say for my eco-8.... what kind of whopper would that take? thanks again, hope these questions aren't bugging you too much, but you've given me a great start. what part of Ohio are you from, I'm from Cortland myself. thanks again.

Brandon

[Argyle]

MorrisM recommended the kit from Slofly as it comes with an aluminum bearing tube which looks easier to mount.

[Argyle]

olmod, are those stats on a 2 cell battery?

[galloping gimp]

Brandon-

I don't know much about the power requirements of helis, so perhaps someone else will respond with information for you.

A good resource for learning what different numbers of stators and turns can do is the Performance Database at GoBrushless.com (http://www.gobrushless.com/testing/motor_test_results.php). The database is oriented towards planes, not helis, but it's a start.

For 3D flying, you'll want a low Kv motor so you can turn a large prop and maximize thrust. A heli will need a higher Kv motor, since there is a gear reduction involved.

I'm in northwest Ohio, about 40 miles SW of Toledo. I'm a member of the Thistledown Flyers (http://www.thistledownflyers.com/).

- Jeff

[helifrek]

thanks for the help jeff, I have some N50 5x5x1 magnets on order, 50 for 5.75 from gobrushless.com not bad, ordered a magnet spacer too, probably not the right size (at work, left motor at home) but, 3 bucks isn't bad, thanks again.

Brandon

[olmod]

olmod, are those stats on a 2 cell battery?
yep, fuly charged maxamps 900 pack.

[Argyle]

Last question I promise:

Did you wind that with 26G wire?

(StrongRC seems to have some really easy to build kits)

[olmod]

I used .5 mm wich is 24g ;) a good wire for winders.
and if you want to run 3sp thats ok too, :)


GWShd 7035 13500rpm @6amps=415.2g=14.66oz.

GWS hd 8040 10.2v 10200rpm@9.75amps =514.60g=18.17oz.

cheers.

[Argyle]

Holy crap, you can get 18oz thrust AND 39 MPH pitch speed with that motor under 10 amps?

That is amazing.

[olmod]

the thrust was calculated using the go brushless rpm/thrust tool.
http://www.lcrcc.net/thrust_calc.htm cheers.

[galloping gimp]

Actually, the GoBrushless.com Propeller Thrust Calculator is here:
http://www.gobrushless.com/testing/thrust_calculator.php

- Jeff

[Argyle]

Ok, so I lied about last question...sue me.

How do you determine rpm speed with a given prop? Do you have a tool to measure it?

[ryanl2006]

Take (RPM x Pitch) x (60 /12 /5280) or RPM x Pitch x .00094697

I am pretty sure thats how you do it...check my math, its late and I'm tired.

[olmod]

Actually, the GoBrushless.com Propeller Thrust Calculator is here:
http://www.gobrushless.com/testing/thrust_calculator.php

- Jeff
Thanks Jeff my bad. :)

[galloping gimp]

Argyle-

The tool for measuring RPM is a tachometer. Click here for an example. (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXPX81&P=ML)

- Jeff

[Argyle]

Ryan, I understand how to calculate pitch speed, thats basic math. I dont understand how to determine RPM of the prop on a given motor at a given voltage. I would assume it requires MotoCalc?

Edit:

Jeff,

Looks like I need to buy one of those, and a thrust stand, as well as a whattmeter (any recomendations?).

[helifrek]

if you know the Kv of the motor it should be Kv x Voltage = motor rpm
multiply that by the throttle setting ie: .50 for half throttle .75 for 3/4ths throttle etc... and with helicopters we multipy by .85 to simulate load..... so...

with a 3500Kv motor on 2S lipos and at 3/4 throttle
3500x7.4=25900rpms times that by .75 = 19425 (throttle setting) and times that by .85 = 16511.25 so that is the final rpm.

I kinda took this from what I know about helicopters and applied it to airplanes, not sure about the load percentage on planes, helicopters have more load I'm sure so you might use 10% instead of 15%, in that case you would mulitply the final by .90 instead of .85 I hope this is somewhat accurate and helps.

Brandon

[helifrek]

hey guys, was looking for late christmas gifts and browsing for things that I may like and stumbled upon this, I am sure it is probably just as easy to set your magnets on a counter and see which way they point... but hey, some of us are lazy :)

http://www.physlink.com//estore/cart/MagneticPolarityIndicator.cfm

Brandon

[galloping gimp]

Looks like I need to buy one of those, and a thrust stand, as well as a whattmeter (any recomendations?).
You can go for a basic meter such as the Astro-Flight or the Watt's Up. Or you can go for a more advanced model such as the Medusa Power Analyzer Plus or Hyperion Emeter, which collect data and let you download it into your computer for further analysis.

Price range for whattmeters is about $50-90. You can sometimes find them for less in the For Sale forums here on RC Groups. I bought a used Astro-Flight for $40 that is all I need.

- Jeff

[Argyle]

Would something like this work for the el cheapo route?

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03482146000&tab=spe#tab

Looks like most of the cheap ones are limited to 10A =/

This one might work a bit better. I doubt I will measure over 20A any time soon:

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03482363000&subcat=Multi-Meters%2C+Testers+%26+Accessories

[galloping gimp]

Would something like this work for the el cheapo route?

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03482146000&tab=spe#tab

Looks like most of the cheap ones are limited to 10A =/

This one might work a bit better. I doubt I will measure over 20A any time soon:

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03482363000&subcat=Multi-Meters%2C+Testers+%26+Accessories
Yes, multimeters such as the Sears units will work, but they are very inconvenient compared to a dedicated whattmeter. The big advantage of a whattmeter is that it connects right inline between your battery and ESC and displays several measurements at once. Here's a photo of a Watt's Up meter, so you can see what I mean.

http://www.balsapr.com/pimages2/wattsupblue.jpg

If you are thinking of spending $39.95 on the better Sears meter, please consider spending a similar amount on a used whattmeter instead. You'll be much happier!

- Jeff

[Argyle]

Ah, so instead of trying to realign all of the settings on a conventional meter to get synchronized measurements, you can get a "snapshot" of all readings at the same time.

Makes sense to me.

As always, I appreciate the help Jeff...I have alot to learn, and it would be hard to accomplish without people that take the time to help.

[galloping gimp]

Ah, so instead of trying to realign all of the settings on a conventional meter to get synchronized measurements, you can get a "snapshot" of all readings at the same time.
That is exactly correct. The alternatives are:

1. Measure only one parameter at a time with the conventional meter, which means you'll never know exactly how your power system is behaving at a given time.

OR

2. Get two conventional meters and connect them so you can measure voltage with one meter and current with the other. By the time you've done that, your cost might exceed the cost of a single whattmeter type meter. And you'd still have to perform calculations to determine information that the whattmeter displays directly.

OR

3. Get a whattmeter and see all of the critical values at once. And a whattmeter is so easy to hook up and use that it encourages you to experiment and learn about your power systems.

If you already own one or two conventional meters, you could argue that it makes sense to use them. But even so, I would say that a whattmeter is essential if you ever aspire to do more than simply duplicate the power systems used by others.

- Jeff

[Argyle]

The more I realize what I have to learn, the more I want to experiment. I'm compulsive like that...

After I buy a DIY kit, the next $100 I spend will be on a thrust stand and a whattmeter.

[BeavrdamElectric]

2 Harbor Freight meters for $3 ea. (on sale) plus a piece of 1/8" plywood, some velcro and a pair of plugs. I've measured 12+ amps, Rysium says they're good for 20. I should shorten the leads some. I might also use a bigger piece of plywood to hold my tach too.

Good Luck!

[Garrett1234567]

Hi everybody, i just rewound my first motor, its a 9 pole so i used ABCABCABC and a star connection. I have 2 more burnt motors but they have 12 poles. What is the wiring order for a 12 pole stator. If ive confused anyone ill try to explain it better. Heres a video of my 9 pole motor on a homemade flatout. http://www.youtube.com/watch?v=2CgWl8Pf6PY

[flydiver]

That looks like it might nave been the TP2408-21?

Most of the rest of the TP are 12 pole > wind dLRK. Here's a tutorial using the Blue Wonder.
http://www.rcgroups.com/forums/showthread.php?t=736580

[Garrett1234567]

Something like it, it came off a parkflyers rtf geebee. The motor had no maarkings or sticker, i believe 1000kv. thanks for the link. il;l get to other 2 wired and lett yo know how it goes.

[Ron van Sommeren]

Must read rewinding introduction:
www.gobrushless.com
-> knowledge base
-> basic overview (1-5)

Tips and tricks, checks and tests, may keep you from frying yer ESC and/our controller:
http://www.rcgroups.com/forums/showthread.php?t=240993