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Old Oct 30, 2011, 08:14 AM
hass-alfed and bass-ackwards
carlsoti's Avatar
United States, AZ, Chandler
Joined Jun 2008
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Originally Posted by Truglodite View Post
this is where I make the turn for the darkside.
Bring back cookies. They have them!
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Old Oct 31, 2011, 04:47 PM
ChangeBegins AtTheDinnerTable
killowatt's Avatar
Raleigh , N.C.
Joined Jun 2006
422 Posts
Ok my eyes are bleeding , soo much great info ! Can someone make a recomendation for a wind using a newer black turnigy 2730 ? My club is racing fireflys on 3s 1000-1300 mah batterys , on gws 8x4 props we run six minute heats .
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Old Oct 31, 2011, 05:10 PM
Winging it >
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Joined May 2006
9,707 Posts
Quote:
Originally Posted by Truglodite View Post
My Eclipse flew OK with the 10P-12T-24awg-D at 260W. So why not push it harder? Although just flying it this weekend would be fun enough, just for you guys I put my latest creation on the stand this evening:

T2730-10p-6x2T-24awg-Y (3650Kv)
Rhino 3s1250 30c (full charge)
APC 4.1x4.1e
31301RPM/11.26V/29.1A/122mph/69.0% DCalc effy

There is a lack of props and no load... would have been fun enough to just fly it.

Efficiency is low on the bench, but the plane is slippery. 100W of dissipated heat is a whole lot for a 25gm outrunner to handle, but I'm not expecting problems with open air cooling at those speeds. Tomorrow's test flight should see around 130mph average. After a certain point increasing cell count becomes necessary. I doubt going beyond 3650Kv on 3s would be fruitful. So now I'm looking at a 2730-10p-8x2T-25a-Y 10p motor mounted on the test stand with a 4.1x4.1e attached, waiting for 4s. If I have time I'll try my 12D stator too... this is where I make the turn for the darkside.

Cheers,
Kev
I'd like to try that motor on my pizza box flyer.
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Old Oct 31, 2011, 05:27 PM
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Carmichael, CA
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Originally Posted by killowatt View Post
...using a newer black turnigy 2730 ? My club is racing fireflys on 3s 1000-1300 mah batterys , on gws 8x4 props we run six minute heats .
A 14p-12T-Y would be a good starting point for that mission. With 24awg windings (medium easy), 8040hd, and a TP 3s730 20C, I measured 11.12V/11.70A/11263RPM/24oz/42.7mph. DCalc says that's 24.2oz, 69.4% efficient @ 29m/26.6C. With larger packs and constant WOT it will get a little hot, but probably survive if you can achieve near pitch speed with open airflow. I'm not familiar with the firefly?

Kev
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Old Oct 31, 2011, 05:32 PM
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Carmichael, CA
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Originally Posted by leadfeather View Post
I'd like to try that motor on my pizza box flyer.
I am familiar with the pizza box flyer... you'll need like 12s to get good speed out of it.

Kev
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Old Oct 31, 2011, 05:37 PM
ChangeBegins AtTheDinnerTable
killowatt's Avatar
Raleigh , N.C.
Joined Jun 2006
422 Posts
Thanks for the direction ! The firefly is one of leadfeathers designs , epp delta and a serious amount of not so serious fun .
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Old Oct 31, 2011, 05:48 PM
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Carmichael, CA
Joined Feb 2007
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4s...

Quote:
Originally Posted by carlsoti View Post
Bring back cookies. They have them!
I didn't get past the entry, but they had treats for Halloween:

T2730-10P-8x2T-26awg-Y (flat silver magnets)
Nanotech 4s1800 35C (store charged)
APC 4.1x4.1e
31008RPM/14.45V/20.66A/120mph/DCalc 20.3oz 73.5% efficient

Cheers,
Kev
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Old Oct 31, 2011, 05:49 PM
Winging it >
leadfeather's Avatar
Joined May 2006
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Quote:
Originally Posted by Truglodite View Post
I am familiar with the pizza box flyer... you'll need like 12s to get good speed out of it.

Kev
So far with a 3000 kV stock blue wonder, 1100 mAh 3s, I'm getting 75 mph.

pbf speed contest thread

pbf speed.wmv (2 min 9 sec)


sPEEDy dELIVERy.wmv (0 min 39 sec)
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Old Oct 31, 2011, 05:53 PM
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Carmichael, CA
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I'm in for sure lf!

Kev
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Old Oct 31, 2011, 06:25 PM
Winging it >
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Originally Posted by Truglodite View Post
I'm in for sure lf!

Kev
Cool. I'm guessing you could push it over 100 mph.
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Last edited by leadfeather; Nov 01, 2011 at 07:55 PM.
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Old Oct 31, 2011, 08:56 PM
hass-alfed and bass-ackwards
carlsoti's Avatar
United States, AZ, Chandler
Joined Jun 2008
5,306 Posts
Quote:
Originally Posted by Truglodite View Post
this is where I make the turn for the darkside.
Quote:
Originally Posted by carlsoti View Post
Bring back cookies. They have them!
Quote:
Originally Posted by Truglodite View Post
I didn't get past the entry, but they had treats for Halloween:
Cheers,
Kev
See here...
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Old Dec 03, 2011, 08:23 PM
hass-alfed and bass-ackwards
carlsoti's Avatar
United States, AZ, Chandler
Joined Jun 2008
5,306 Posts
Quote:
Originally Posted by Truglodite View Post
My Eclipse flew OK with the 10P-12T-24awg-D at 260W. So why not push it harder? Although just flying it this weekend would be fun enough, just for you guys I put my latest creation on the stand this evening:

T2730-10p-6x2T-24awg-Y (3650Kv)
Rhino 3s1250 30c (full charge)
APC 4.1x4.1e
31301RPM/11.26V/29.1A/122mph/69.0% DCalc effy

There is a lack of props and no load... would have been fun enough to just fly it.

Efficiency is low on the bench, but the plane is slippery. 100W of dissipated heat is a whole lot for a 25gm outrunner to handle, but I'm not expecting problems with open air cooling at those speeds. Tomorrow's test flight should see around 130mph average. After a certain point increasing cell count becomes necessary. I doubt going beyond 3650Kv on 3s would be fruitful. So now I'm looking at a 2730-10p-8x2T-25a-Y 10p motor mounted on the test stand with a 4.1x4.1e attached, waiting for 4s. If I have time I'll try my 12D stator too... this is where I make the turn for the darkside.

Cheers,
Kev
Kevin(Or anyone else who knows),

A question about magnets in relation to high kv winds(say 3000kv ish)...

If one were to arrange the magnets from a 16 mag motor from n-s-n-s...etc to NN-SS-NN-SS...etc besides the lowered switching speeds seen by the ESC, what would be the advantages/disadvantages as compared to just having 8 mags?
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Old Dec 04, 2011, 01:10 AM
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Carmichael, CA
Joined Feb 2007
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There are a few pros and cons in turning a 16p motor in to an 8p 16 magnet motor like you mention. A pro would be you would have more torque than 8magnets. As far as magnet coverage it seems like a wash to me; ppl say 80% is ideal... 16mag ~100%, 8mag ~50%. So 16mag is closer to 80%, but at such high rpm those eddy currents are a big concern (more magnetic flux = more eddy loss). There's too many variables for me to say one would be better than the other.

IMHO it would be a worthwhile experiment testing both. Pop 8 alternating magnets out, run the test, then glue the 8 magnets back in nn-ss, and run another test. Not much more work to get a solid comparison.

On a side note, being able to reverse the poles is one undeniable benefit to the new flat magnets. When the curved style magnets are flipped over, they hit the stator.

Kev
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Old Dec 04, 2011, 02:16 PM
Dave North
timocharis's Avatar
USA, CA, San Jose
Joined Apr 2004
5,254 Posts
From a flux channeling standpoint it's best if the mags are not bigger than the head of the tooth. When you double up magnets to such a greater width you confuse the motor a bit and it goes inefficient. Having the wider gaps creates stuttering, though. Which is why such motors really have to be designed from the ground up, so to speak.

Dave
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Old Dec 04, 2011, 02:51 PM
hass-alfed and bass-ackwards
carlsoti's Avatar
United States, AZ, Chandler
Joined Jun 2008
5,306 Posts
fair enough, thanks guys.
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