HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jan 25, 2010, 07:56 PM
Go ahead... Build it to crash!
Fuegodeth's Avatar
Conroe, TX
Joined Apr 2007
2,630 Posts
Timing and switching frequency would be the ones to mess with. I believe low advance timing and higher frequency are better for outrunners. Outrunners take lots of switching cycles to make one rotation (7 for dlrk, 8 for ABC 16mags), where as inrunners are have 2 poles so less switching, and more angular turn per switching cycle. The castle thunderbird controllers always seem to run great as they are expecting outrunners mostly. Although, I also run them on my inrunners and they run well as well. I have no experience with the Hyperion Esc's, but I guess they don't auto detect, so best to set them and make sure. It might save you a rewind of a motor...
Fuegodeth is offline Find More Posts by Fuegodeth
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 26, 2010, 02:22 AM
Registered Aircraft Offender
Truglodite's Avatar
Carmichael, CA
Joined Feb 2007
3,517 Posts
Quote:
Originally Posted by gregallen View Post
Kev,

I wound the motor 14T Wye and it still chatters I don't have a tach so this is the only data I can provide for full power: 5.8Ap 7.3Vm at 43.4W on an 8x6 APC SF. Do these #'s sound correct for this rewind? I just swapped ESC again and no help. A side note, these ESC's were running two Hyperion 12mm can motors in my A-10 previously and seemed to be working fine at the time.

I think I'm going to switch bullet connectors. The ones that came with it have a spring loaded barrell on the male side that may be too loose. Not sure.

If this doesn't work out I might try making a short vid, just to be sure that my text discriptions of the problem are accurate!
I bet you're overloading the motor with that prop. Most people are running a GWS 9050HD on that setup, and the APC 8x6sf loading is about 50% greater. At a glance, it takes about 38W output to spin an APC 8x6sf at 6000RPM, versus only 26W to spin a GWS 9050HD at the same RPM. Try propping down a bit and see how it runs. A 9050hd is probably going to work, but if you have to use an APC sf I'd go with a 9x3.8sf, which is very close in loading to the GWS9050hd at these RPMs.

Cheers,
Kevin

[edit: Below I attached loadings at 7500RPM based on DCalc Nov '09. More than likely your RPM will be lower, but the relative load ranking of the props doesn't change too much so it'll give you a decent idea of what to use. Although, what's weird is that your amp draw is so low. Maybe the esc is current limiting... or it's an older battery?]
Truglodite is offline Find More Posts by Truglodite
Last edited by Truglodite; Jan 26, 2010 at 02:36 AM.
Reply With Quote
Old Jan 26, 2010, 05:56 AM
Registered User
Atlanta
Joined Jan 2010
8 Posts
I can't go any bigger in diameter, but I do have a 7" APC slow fly available to try. APC only because they are the ones at the LHS. I didn't think "over proped" would come into play at start up? I think the overall weight/torque the motor needs to overcome to get going is a factor. With no prop on it spins right up.

The batteries are new, bought just for this airplane. I thought since it was holding 7.4V at 40W it was doing its job. Is that not a good voltage under load for a 2S?

Quote:
Originally Posted by Truglodite View Post
[edit: Although, what's weird is that your amp draw is so low. Maybe the esc is current limiting... or it's an older battery?]
I've taken a short video and have been trying to upload it to youtube (first time) with no success so far. I think that will show a lot about what is going on.

What do you guys use to determine RPM when your testing your motors?

Greg
gregallen is offline Find More Posts by gregallen
Reply With Quote
Old Jan 26, 2010, 06:07 AM
I'm overcoming gravity!
Murman's Avatar
USA, NC, Huntersville
Joined Jul 2008
3,913 Posts
Quote:
Originally Posted by gregallen View Post
...I wound the motor 14T Wye and it still chatters
This may sound like a simple solution, but I've overlooked it on a couple of occasions. Did you remember to scrape the insulation from the ends of the wires before terminating and before soldering your connectors?
Murman is offline Find More Posts by Murman
RCG Plus Member
Old Jan 26, 2010, 07:21 AM
A real WingNut
j4ck4's Avatar
United States, OK, Tulsa
Joined Dec 2008
920 Posts
How can I take one of these blue and red motors or one of the Kextroniks I posted about earlier and turn it into this.
http://www.rcfoam.com/cart.php?targe...ategory_id=152
Also, I got the Hextronic wound, ended up winding it with 18 turns of what I believe is 26 ga. maybe 30 I do have a lot of room left on the stator poles.
j4ck4 is offline Find More Posts by j4ck4
Reply With Quote
Old Jan 26, 2010, 04:04 PM
Registered Aircraft Offender
Truglodite's Avatar
Carmichael, CA
Joined Feb 2007
3,517 Posts
More data on the 12T-24a-D

I bench tested 3 more props on my 12-turn 24awg delta (some data copied over from my earlier post# 399):

Turnigy 2730-14P-12T-24a-D
Measured Rm
Phase1=Phase2=Phase3= 0.0499ohm

No Load
29627 RPM / 12.42 V / 1.066 A
-> 2386Kv

TP 3s850 PP (fully charged)
Phoenix 25 (v1.55, defaults)
Ambient: 29m alt, 17.5C temp
APC 4.2x4e / 24630 RPM / 11.74 V / 12.62A / 7.9 oz / 98.0 mph / ???%
GWS 4040HD / 23942 RPM / 11.59 V / 12.99A / 12.0 oz / 90.7 mph / 58.5%
GWS 4540HD / 23809 RPM / 11.56 V / 13.62A / 18.7 oz / 90.2 mph / 69.9%
APC 4.75x4.75e / 21978 RPM / 10.85 V / 17.85 A / 15.8 oz / 98.9 mph / 85.4%
Grp CamSpd 4.7x4.7 / 22205 RPM / 10.88 V / 17.29 A / 15.4 oz / 98.8 mph / 106.6%
Grp CamSpd 5.2x5.2 / 20408 RPM / 10.73 V / 23.20 A / 20.0 oz / 100.5 mph / 83.2%

*effy and thrust from Dcalc & DrKiwi

Although the GWS4540hd was not vibrating quite as bad the 4040, it was making enough weird noises. I derived the thrust coefficient for the APC 4.2x4e from Phil's data (thanks Phil ), but I still haven't got a hold of dyno data on that prop. Out of curiosity I plugged in the power coefficients from an APC 4.1x4.1e and got 76.9% effy, which seems pretty close.

Anywho, all we need really are different loadings for DCalc to do it's thing. The APC 4.2x4e and GWS 4040HD are almost identical loads, so we throw out the GWS since it was vibrating. The GCS 4.7^2 and APC 4.75^2 are also nearly identical loads, so we'll pick the more common one (APC). The GWS 4540HD did vibrate, and who knows how that would play in to things; but since it's a load between the 2 APC's, we add it in. Lastly, the GCS 5.2^2 isn't a common bugger, but it's a smooth load that should be well past the efficiency peak, so I'm including it. That's 4 distinctly different loads, which should be good for a calculator program.

Now what we have is something that looks more reasonable... but I have no idea why the DCalc rating is so low. Maybe it somehow knows those prop constants are way off... maybe it see's weird results from the shaking 4540hd? I know the motor data is following the power curve pretty closely. I'm not sure why DCalc is protesting, but the numbers on the GCS 5.2^2 look pretty nice to me, so that's what I'll be trying it out with this Sunday. I know, I said that last weekend, but it rained all day.

Cheers,
Kev

[edit: A Red'n'blue at 250W... I think I'm going crazy, but somehow I believe this is going to be OK. Even if it smokes, I might finally get one of my d4mn planes to break 100mph. LOL!]
Truglodite is offline Find More Posts by Truglodite
Last edited by Truglodite; Jan 26, 2010 at 04:12 PM.
Reply With Quote
Old Jan 26, 2010, 04:37 PM
Dave North
timocharis's Avatar
USA, CA, San Jose
Joined Apr 2004
5,254 Posts
If a prop freaks out at all during testing, toss that result. Nevertheless, you're showing good numbers so, ya know? Be happy! Hmm. Are the Gunther 5" props still around anywhere? Not the most efficient, but not bad and they could take some spin.


Dave
timocharis is offline Find More Posts by timocharis
Reply With Quote
Old Jan 26, 2010, 04:42 PM
Registered Aircraft Offender
Truglodite's Avatar
Carmichael, CA
Joined Feb 2007
3,517 Posts
I'm happily satisfied, and even more so if it doesn't rain in Antioch on Sunday.

I haven't owned a Gunther... haven't seen 'em at my LHS either.

Kev
Truglodite is offline Find More Posts by Truglodite
Reply With Quote
Old Jan 26, 2010, 06:26 PM
Registered User
Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
27,199 Posts
The white Gunther 4.92x4.33 can't take a lot of rpm.. a slightly larger prop to try is the Maxx 5x5... it's not quite as good as the Zagi Carbon 5.1x4.9 ... but it is pretty good.
Dr Kiwi is offline Find More Posts by Dr Kiwi
Reply With Quote
Old Jan 26, 2010, 09:05 PM
Dave North
timocharis's Avatar
USA, CA, San Jose
Joined Apr 2004
5,254 Posts
Defer. I never did try spinning up the Gunther _that_ high.


Dave
timocharis is offline Find More Posts by timocharis
Reply With Quote
Old Jan 26, 2010, 09:20 PM
I can fix that.
United States, PA, Mountain Top
Joined May 2006
273 Posts
Quote:
Originally Posted by Truglodite View Post
Turnigy 2730-14P-12T-24a-D
Would the approx equivalent 16P motor be something like 11T 23g or 24g Delta?

This wind makes a nice little speed motor.

-Ken
solomonx is offline Find More Posts by solomonx
Reply With Quote
Old Jan 26, 2010, 11:30 PM
Registered Aircraft Offender
Truglodite's Avatar
Carmichael, CA
Joined Feb 2007
3,517 Posts
11turn would be a tad hotter, or 12turn would be a tad lower Kv, so depends on what you want. I doubt either will fit in 23awg, so 24awg. One thing to consider doing this with a 16pole is switching frequency. Even with 14poles (7 switches/rev) my esc is being pushed to the ragged edge, and 16poles (8 switches/rev) will be even worse for the esc. I mean, my esc felt just as hot at no load as it did with the 5.2^2, so switching is taking it's toll. Either way I'd recommend excellent cooling for both the motor and esc. On my scrappy everything is hanging out in the airstream.

Kev
Truglodite is offline Find More Posts by Truglodite
Reply With Quote
Old Jan 26, 2010, 11:34 PM
I can fix that.
United States, PA, Mountain Top
Joined May 2006
273 Posts
Quote:
Originally Posted by Truglodite View Post
12turn would be a tad hotter, or 11turn would be a tad lower, so depends on what you want. I doubt either will fit in 23awg, so 24awg. One thing to consider doing this with a 16pole is switching frequency. Even with 14poles (7 switches/rev) my esc is being pushed to the ragged edge, and 16poles (8 switches/rev) will be even worse for the esc. I mean, my esc felt just as hot at no load as it did with the 5.2^2, so switching is taking it's toll.

Kev
Thanks! Forgot about the switching freq.
solomonx is offline Find More Posts by solomonx
Reply With Quote
Old Jan 27, 2010, 12:22 AM
Registered Aircraft Offender
Truglodite's Avatar
Carmichael, CA
Joined Feb 2007
3,517 Posts
I didn't mean that to scare you off, but just as a precaution. Here's a link to switching limits for various brand esc's:

http://www.bavaria-direct.co.za/mode...ontrollers.pdf

Take the 2-pole RPM limit, multiply by 2, then divide by "X" to find out the RPM limit for a motor with "X" poles. So for example my Phoenix esc can theoretically drive a 16pole motor to 45000RPM. On the other hand, there are many brands that cannot get a 16pole motor past 20kRPM. Also, when you're getting close to the current limit of the esc, the closer you get to that RPM limit the more critical cooling becomes.

Kev

[edit: I wouldn't be comfortable running at the current and RPM limits simultaneously. To be safe, the esc should be "derated" as it approaches it's RPM limit. I have no idea exactly how much an esc should be derated based on switching though; perhaps just a ground test to make sure the esc isn't heating up too much would be a good idea.]
Truglodite is offline Find More Posts by Truglodite
Last edited by Truglodite; Jan 27, 2010 at 12:29 AM.
Reply With Quote
Old Jan 27, 2010, 09:57 AM
I can fix that.
United States, PA, Mountain Top
Joined May 2006
273 Posts
Quote:
Originally Posted by Truglodite View Post
I didn't mean that to scare you off, but just as a precaution. Here's a link to switching limits for various brand esc's:

http://www.bavaria-direct.co.za/mode...ontrollers.pdf
Thanks for that link Kev! You didn't scare me off. I have wound a bunch of GB 20mm stators in both 12P and 6P from CustomCDR. I have never run into switching problems. Now that there is no more CustomCDR, I have turned to the 2730's.

Btw, you can get 12T 23g on the stators without too much difficulty, but you have to cheat a little bit. With a small file, square each tooth and round the sharp corners afterwards. You have to be careful not to go all the way through to the metal. Really not much difference at all to the 12T 24g results that were posted here. I did it once, but not worth all the effort to do it again. I will stick with 24g.

-Ken
solomonx is offline Find More Posts by solomonx
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold 14-turn 25awg dLRK Turnigy "Blue'n'Red Wonder" Outrunner $23 Shipped timocharis Aircraft - Electric - Power Systems (FS/W) 3 Mar 21, 2009 01:38 PM
Sold Rewound 13-turn 24awg Turnigy "Blue Wonder" Outrunner $24 Shipped timocharis Aircraft - Electric - Power Systems (FS/W) 6 Mar 08, 2009 10:37 PM
blue core stringless wonder larry g Foamies (Kits) 9 May 27, 2003 10:06 AM