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Old Dec 19, 2010, 07:36 PM
Winging it >
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Quote:
Originally Posted by Dr Kiwi View Post
For the same power input, fairly obviously, the larger the diameter of the prop, the more thrust you can get. Determine the maximum diameter your VTOL can use, and go from there.
I thought a lower kV motor driving a larger prop would give the most thrust/watt??? I'm not just looking for max thrust, but as I stated, I'm after static thrust efficiency. Any feedback on proven combinations of low kV winds and big props would be appreciated.
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Old Dec 19, 2010, 07:58 PM
hass-alfed and bass-ackwards
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United States, AZ, Chandler
Joined Jun 2008
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Here's a post from WAY back in this thread that seems somewhat pertinant.
Quote:
Originally Posted by timocharis View Post
...the client preferred this motor, which is indeed a Wye!

Tgy 17T 25g ABC Wye Kv 1031 (7907/7.67) Io = 0.36 Rm = 0.281
GWS 1147 RS Rhino 610 2S
4204 rpm @ 7.41v/7.36a
Badcock: 426 grams 15.0 oz/thrust 61.7% Efficient
DriveCalc: 438 grams 15.5 oz/thrust 62.8% Efficient

I never flew either one, so if you're going to give it a shot, go with his preference. At least, that would be my recommendation!


Dave
FWIW, he also did another wind that was around 900kv that spun a 1047 on 3S, but the efficiency was crap...around 50%.

You might need to wind down to 700kv or so, to spin a prop that big on 3S with decent efficiency.

These are "little" motors.
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Old Dec 19, 2010, 08:08 PM
hass-alfed and bass-ackwards
carlsoti's Avatar
United States, AZ, Chandler
Joined Jun 2008
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Some more pertainant infor from the first page. If you click on the little arrow next to the quote, you will get the attatchments from the original posts.

Quote:
Originally Posted by timocharis View Post
Interesting problem somebody posed. I think this is actually a bit too soft, but you never know when trying to turn big props with little motors. Sometimes when you drop a turn or two you don't get any more rpm, you just get more current sucked.

Anyway, this one produces about 15oz thrust at 7.3 amps 7.4 volts. RPM was 4204. Kind of a nifty look (this is an ABC 16-mag).


Dave
Quote:
Originally Posted by manuel v View Post
Alex.

For your plane, I do not think it is practical to use a propeller 8x4, let alone a 9x4.
at least for the blue wonder. is ok. for 3s and 12 tuens star.

I like for a model of that size and the type of plane and an APC 6x4 a 5x5 minimum.

I am sending you the table of bw. to choose the combination that best provide for your needs.

Manuel V.
Quote:
Originally Posted by timocharis View Post
Used 28awg. Weird idea: somebody likes turning an 11x4.7 with the BW, so this was one attempt (pretty good, really, and easy on the battery):

Tgy 2730 32T 28awg dLRK Delta
Kv 988 (8002/8.1v) Io = 0.35 Rm = 0.373
GWS 1147 RS Rhino 610 2S 4046 rpm @ 7.60v/6.83a
Badcock: 372 grams 13.1 oz/thrust
Drive Calc: 403 grams 14.2 oz/thrust
Quote:
Originally Posted by manuel v View Post
No. turns for any KV.
DLRK 14 magnets.

Manuel V.
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Old Dec 19, 2010, 11:06 PM
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data

I had a look at the chart from post #44 of this thread. Lots of hard work to do all the testing and compiling, thanks to those involved.

I sorted the charts in two different ways, by efficiency and by lowest power to thrust ratio. I also removed the 2s data since I plan on using 3s for my project.

The overall trend is pretty much as expected, lower kV motors appear to give better efficiency....no surprise.

The chart that was sorted by power/thrust also showed something I wasn't expecting. The 950 kV wind had one of the best efficiencies, but the same motor dropped in efficiency and went up in power over thrust when used with a larger 9" prop compared to the best 8" prop. Interesting! I hope I'm not misinterpreting the data.
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Old Dec 28, 2010, 08:26 PM
Expo is built into my thumbs
Hance's Avatar
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I did a hot wind blue wonder today. It has 7 turns of the heaviest gauge wire I could stuff on it. It should be in the 4500kv range. That should pull the adrenaline rush around like a rocket.
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Old Jan 01, 2011, 10:18 PM
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ESC elimination: Dc supply to 3 Phz = Test Rig

Hope I'm in the correct area for info : I'm a Newbie after 40 year's Nitro/ Gas
and just learning to re- wind ;Just did my first

I happen to have a DC supply, which is calibrated in both Volts and Milli amp's { meter's will slave together and is switchable 0 V= " 6 V/ to 12 V up to a 10 amp out put.

Would like to incorporated it into a thrust / rPM counterbalance test rig using a digital weight scale and my High Point.

MY question arises ::: IS their a method to eliminate the ESC in the test loop in which I can jump from the DC supply directly to 3 Phaze timing into the motor or must I pick a large ESC to obtain the phase timing pulse.

Just what is in side the ESC to perform this function. ??? I'm aware how a bridge rectifier works in converting 3 phase back to DC. But it's back ward's for this application.

Is their a plug and play directly from the DC ??
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Old Jan 01, 2011, 10:23 PM
Expo is built into my thumbs
Hance's Avatar
USA, ID, Niter
Joined Jul 2008
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Quote:
Originally Posted by Jack H View Post
Hope I'm in the correct area for info : I'm a Newbie after 40 year's Nitro/ Gas
and just learning to re- wind ;Just did my first

I happen to have a DC supply, which is calibrated in both Volts and Milli amp's { meter's will slave together and is switchable 0 V= " 6 V/ to 12 V up to a 10 amp out put.

Would like to incorporated it into a thrust / rPM counterbalance test rig using a digital weight scale and my High Point.

MY question arises ::: IS their a method to eliminate the ESC in the test loop in which I can jump from the DC supply directly to 3 Phaze timing into the motor or must I pick a large ESC to obtain the phase timing pulse.

Just what is in side the ESC to perform this function. ??? I'm aware how a bridge rectifier works in converting 3 phase back to DC. But it's back ward's for this application.

Is their a plug and play directly from the DC ??
No you have to have an esc of some kind. The esc acts as a switch basically if you hook direct to the power supply it will just see a dead short until the magic smoke leaves something.
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Old Jan 01, 2011, 10:39 PM
Curiouser and curiouser
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Rochester, NY, USA
Joined Oct 2005
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Quote:
Originally Posted by Jack H View Post
Hope I'm in the correct area for info : I'm a Newbie after 40 year's Nitro/ Gas
and just learning to re- wind ;Just did my first

I happen to have a DC supply, which is calibrated in both Volts and Milli amp's { meter's will slave together and is switchable 0 V= " 6 V/ to 12 V up to a 10 amp out put.

Would like to incorporated it into a thrust / rPM counterbalance test rig using a digital weight scale and my High Point.

MY question arises ::: IS their a method to eliminate the ESC in the test loop in which I can jump from the DC supply directly to 3 Phaze timing into the motor or must I pick a large ESC to obtain the phase timing pulse.

Just what is in side the ESC to perform this function. ??? I'm aware how a bridge rectifier works in converting 3 phase back to DC. But it's back ward's for this application.

Is their a plug and play directly from the DC ??
Whoa!
Can't do that!
Reason is:
The brushless motor is NOT a direct current motor - it is an alternating current motor - the ESC converts dc to three phase ac and controls the frequency of the ac to control the speed of the motor.
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Old Jan 02, 2011, 12:29 AM
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Very aware that it is a 3 Phase, and not DC : What magic smoke is in the ESC
that adjusts the phase timing or pulse ? My end goal is to end up with a basic test rig without a RX - TX and maybe the ESC.

Could I just maybe neuter the RX side of the ESC ?

Pondering the use a manual optical tac for RPM . The digital scale to measure thrust, the mill /amp meter for draw , the mill volt meter on the supply for input voltage.
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Old Jan 02, 2011, 12:53 AM
Expo is built into my thumbs
Hance's Avatar
USA, ID, Niter
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Quote:
Originally Posted by Jack H View Post
Very aware that it is a 3 Phase, and not DC : What magic smoke is in the ESC
that adjusts the phase timing or pulse ? My end goal is to end up with a basic test rig without a RX - TX and maybe the ESC.

Could I just maybe neuter the RX side of the ESC ?

Pondering the use a manual optical tac for RPM . The digital scale to measure thrust, the mill /amp meter for draw , the mill volt meter on the supply for input voltage.
I don't know a lot about them but the motor feeds signal back to the esc on the phases that aren't powered at the time. This let's the esc figure out what position the motor is in so it knows when to turn off the current phase and turn on the next one. Lucien Miller from scorpion did a great job explaining it on an episode of all things that fly podcast awhile back. You may want to look it up. Www.allthingsthatfly.com
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Old Jan 02, 2011, 09:37 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by Jack H View Post
Very aware that it is a 3 Phase, and not DC : What magic smoke is in the ESC
that adjusts the phase timing or pulse ? My end goal is to end up with a basic test rig without a RX - TX and maybe the ESC.

Could I just maybe neuter the RX side of the ESC ?

Pondering the use a manual optical tac for RPM . The digital scale to measure thrust, the mill /amp meter for draw , the mill volt meter on the supply for input voltage.
I think you've just missed some of the changes that have evolved over time. At least as far as how it works for RC brushless motors. There were brushless motor ESC's with sensors, then it happened that sensorless ESC's were a better option. Maybe reading this will help explain it a little:

http://www.teamnovak.com/tech_info/b...ensorless.html

The ESC's now, for the most part, read the back-EMF from a second phase, make a logical decision, and the motor runs. I think the bottom line is that you can either build or buy an ESC but you have to understand how they work.

Jack
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Old Jan 02, 2011, 01:47 PM
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Carmichael, CA
Joined Feb 2007
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Quote:
Originally Posted by Hance View Post
I did a hot wind blue wonder today. It has 7 turns of the heaviest gauge wire I could stuff on it. It should be in the 4500kv range. That should pull the adrenaline rush around like a rocket.
What a coincidence. This year I was planning on doing an AR with a rewound blue wonder too; something to warm up with before I toss up the D99. Looks like you're going for a hefty 2s setup, I was thinking of winding for 3s460 or 4s360. I'm curious how your AR will fly.

Kev
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Old Jan 08, 2011, 10:32 PM
Foam, foam on the range....
didge's Avatar
Adelaide, Australia
Joined Feb 2009
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3000kv now ABC?

Has anybody bought a 3000kv lately?

I can't find it now, but I seem to recall some mention somewhere of them having changed from DLRK to now being ABC, although the picture on the HK site looks like it has 14 magnets http://www.unitedhobbies.com/UNITEDH...idProduct=8620

I just thought I would ask, because as we all know, any resemblance between the picture and the actual article received is, of course, purely arbitrary...

Cheers
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Old Jan 08, 2011, 10:44 PM
Expo is built into my thumbs
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Quote:
Originally Posted by didge View Post
Has anybody bought a 3000kv lately?

I can't find it now, but I seem to recall some mention somewhere of them having changed from DLRK to now being ABC, although the picture on the HK site looks like it has 14 magnets http://www.unitedhobbies.com/UNITEDH...idProduct=8620

I just thought I would ask, because as we all know, any resemblance between the picture and the actual article received is, of course, purely arbitrary...

Cheers
I just bought two of them from hobby king http://hobbyking.com/hobbyking/store...idProduct=5453 I should get them this coming week sometime.
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Old Jan 08, 2011, 10:54 PM
Foam, foam on the range....
didge's Avatar
Adelaide, Australia
Joined Feb 2009
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Quote:
Originally Posted by Hance View Post
I just bought two of them from hobby king http://hobbyking.com/hobbyking/store...idProduct=5453 I should get them this coming week sometime.
Hance, thanks for your reply - that's the Hextronic version you've bought - I'll look forward to your report with interest!

Cheers
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