News:



Advertise Here

  • July 20, 2019, 11:18:42 PM

Login with username, password and session length

Author Topic: Help with Motor Overheating!  (Read 23843 times)

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Help with Motor Overheating!
« on: July 03, 2015, 01:13:35 PM »
I need some help.  This is on my Legacy 40 I just completed a few months ago.  When I first flew it, at the end of a full flight the motor temp was like 190 degrees F!  Yikes.  The battery and ESC temps were fine.  Since then I added a baffle in the intake are passage to deflect the air upward toward the motor.  The temp went down like 10 degrees.  I then redid my battery mounting system thinking that the tray and battery straps were blocking a lot of air.  The motor temp  is now 165 degrees F.  Getting better but still way too high.

When I started building this model, I widened the fuselage by about 3/8 from 2 inches to 2 3/8 inside width thinking that the extra width would help with the cooling.  Apparently not so!

I'm including a lot of pictures to show what my installation looks like.  I'll give some dimensions too.

Intake hole is 2 inches long with the large end has a 1 1/4 inch 1/2 round and the small end has a 3/4 inch half round.

The exit hole on the bottom of the fuselage is 4 inches long by 1 3/8 wide.

The bulkhead behind the motor has an opening of 1 3/4 by 1 3/4.  The lower opening is 1 3/4 wide by 7/8 high.

The battery sits on the 2 lower crossbeams and is held in place by the 2 swing arms along the top.  It is pretty much wide open all along the battery.

The baffle is about 2 inches wide by 7/8 tall and is about 1 1/4 inches aft of the air intake.

I'm doing a little thinking that the slope of the bottom nose area isn't allowing a lot of air to get into the motor area.  By time it get into the nose area it is behind the motor.  At least that's what I'm thinking.  I know that there are other Legacy 40 electrics flying and I'm assuming that they have no problem with cooling.

Any ideas as to what I need to do to get the temp down to about 125 F?

I know I could cut a scoop into the top and even the sides.  I've read that air is supposed to flow through the motor but I can't see how on a lot of electric models.  I could fly it without a spinner to see what happens but that won't solve my problem.

The motor is a Cobra 2826/10 760Kv with a 5S battery and a Jeti Spin 44 and Igor's Active timer.



 
« Last Edit: July 03, 2015, 04:40:57 PM by Crist Rigotti »
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Online Joseph Daly

  • 2016 supporter
  • Trade Count: (0)
  • Lieutenant
  • *
  • Posts: 118
Re: Help with Motor Overheating!
« Reply #1 on: July 03, 2015, 01:37:39 PM »
I had the same issue with a cobra 2826 - 930kv in a Vegas and I added an air deflector and it helped a little but not enough. I switched to a scorpion 3026 - 890kv and it ran much cooler. For some reason the Cobra ran much hotter.

Online Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 11124
Re: Help with Motor Overheating!
« Reply #2 on: July 03, 2015, 01:44:41 PM »
I could fly it without a spinner to see what happens but that won't solve my problem.

Hey Crist:

Sometimes it is very useful to do a test that you know is doing things "wrong", not because it leads to a solution (you don't want to fly without a spinner), but because you learn what direction you need to go.  It's a good thing to do when you're stuck.  I'd fly the thing without a spinner and check the motor temperature.  If you've blocked off the path of air through the motor I'd open that up.

Looking at the pictures, I see a system that (forgive me for being blunt) does a fine job of piping a lot of air next to the motor without actually running any by, much less through, the motor.

I think that you need to get air moving through the motor.  Here are some random suggestions for a solution to the problem that I think you have.  They won't do a bit of good if the problem isn't lack of airflow through the motor.

  • Make a plenum that goes from your intake scoop to the front of the motor.  If your motor is front mounted on the very front of the fuselage it won't work -- whether you can change things at this point, well, you know.  This means the air will have to reverse direction, which is pretty lossy.  It probably also means that you'll want to divide your scoop to make sure that you're getting fresh air to the electronics, separately from the motor.
  • Assuming that the front of the motor isn't sealed off, put a fan on the back of the motor.  The ones I've seen are just centrifugal fans, and I've heard good things so apparently they work.  The fan will create a vacuum in back, but if it's to suck any air there needs to be an opening in front for air to get pulled in
  • Give up and use an undersized spinner, so the front of the fuselage makes a scoop.  These seem to be very popular, although I see them too much
  • Perforate the spinner
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline John Cralley

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1228
Re: Help with Motor Overheating!
« Reply #3 on: July 03, 2015, 01:52:27 PM »
Hi Crist,

That is a bummer! First I would fly it without the spinner to see if it is then cooled down. I think there are spinners designed to stream air back into the motor area (probably ugly) which might cure the problem.

Secondly I think I would look into ways to force air upward to flow over the motor. You can try blocking off the lower opening in F-2 (Gorilla duct tape??) so that the air must flow upwards around the motor. It is hard to tell from your photos if F-2 is open entirely with a brace (black) in front (below the motor). I also have difficulty visualizing for sure but it looks like the battery is going to be directly behind the motor and the may interfere with air flow too. In other words can the air be simply flowing straight back beneath the battery and pretty much bypassing the motor?

Third possibility is a motor with its own fan.

Keep us post as to your solution.
John Cralley
Scratch Built - Often Re-kitted!!!
AMA 52183
Central Illinois

Online James Mills

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1195
  • Welcome to the Stunt Hanger.
Re: Help with Motor Overheating!
« Reply #4 on: July 03, 2015, 02:10:12 PM »
Crist,

Maybe try a little smaller spinner, let the opening ram a little more air into the motor.

James
AMA 491167

Offline William DeMauro

  • 2019 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 649
Re: Help with Motor Overheating!
« Reply #5 on: July 03, 2015, 03:38:19 PM »
You could try putting a fan on the motor but my gut feeling tells me it wont be enough. If you have room, switch to a 3515 which weighs only a few grams more. you can put a fan on that too. I had the 2826 on voltron and it ran too hot. I went to the scorpion 3026 890 and it ran fine but was hard on bearings. I now have a cobra 3520 on it with a fan and a Ressinger 3 blade on it and it runs at air temp with plenty of power at only a few grams more than the scorpion. At your weight you don't need a 3520 series motor, so I'd go for the 3515. For some reason the 35 series seem to run cooler.
William
AMA 98010

Online Howard Rush

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6589
Re: Help with Motor Overheating!
« Reply #6 on: July 03, 2015, 04:31:28 PM »
Although the ideas people gave you above are better than what I'm about to propose, you might try putting a little downward-deflected flap ahead of the air outlet, maybe making the pressure lower behind the flap.
The Jive Combat Team
Making combat and stunt great again

Online Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 11124
Re: Help with Motor Overheating!
« Reply #7 on: July 03, 2015, 04:34:04 PM »
Hey Crist:

This is totally untried, etc., but it's what I think one needs to do to get airflow through a motor.

See the picture.  I think you need to put a bulkhead in the thing, as shown, that goes all the way across the fuselage.  Make the hole in the bulkhead so that the motor housing barely passes (obviously you don't want it to extend far enough back that the motor bell rubs on the bulkhead).  Make the bulkhead into a scoop that divides the air entry hole so that the top part is guided through the motor, while the bottom part goes over the electronics.

I'd be vastly interested in your results, but if you're more interested in getting into the air and flying, then a motor change or a fan may get you results quicker.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #8 on: July 03, 2015, 04:43:10 PM »
Hi Crist,

That is a bummer! First I would fly it without the spinner to see if it is then cooled down. I think there are spinners designed to stream air back into the motor area (probably ugly) which might cure the problem.

Secondly I think I would look into ways to force air upward to flow over the motor. You can try blocking off the lower opening in F-2 (Gorilla duct tape??) so that the air must flow upwards around the motor. It is hard to tell from your photos if F-2 is open entirely with a brace (black) in front (below the motor). I also have difficulty visualizing for sure but it looks like the battery is going to be directly behind the motor and the may interfere with air flow too. In other words can the air be simply flowing straight back beneath the battery and pretty much bypassing the motor?

Third possibility is a motor with its own fan.

Keep us post as to your solution.

John,
The battery is aft of the bulkhead by about 3/4 inch so I don't think its blocking the airflow around the motor.  Good thought though.
« Last Edit: July 03, 2015, 06:31:21 PM by Crist Rigotti »
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #9 on: July 03, 2015, 04:43:58 PM »
I had the same issue with a cobra 2826 - 930kv in a Vegas and I added an air deflector and it helped a little but not enough. I switched to a scorpion 3026 - 890kv and it ran much cooler. For some reason the Cobra ran much hotter.

Yeah, I'm getting feedback that the 26mm motors run hot...sigh.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #10 on: July 03, 2015, 04:45:22 PM »
Although the ideas people gave you above are better than what I'm about to propose, you might try putting a little downward-deflected flap ahead of the air outlet, maybe making the pressure lower behind the flap.

Hmm....I could tape one on easily enough.  Thanks for the idea!
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #11 on: July 03, 2015, 04:49:06 PM »
Hey Crist:

This is totally untried, etc., but it's what I think one needs to do to get airflow through a motor.

See the picture.  I think you need to put a bulkhead in the thing, as shown, that goes all the way across the fuselage.  Make the hole in the bulkhead so that the motor housing barely passes (obviously you don't want it to extend far enough back that the motor bell rubs on the bulkhead).  Make the bulkhead into a scoop that divides the air entry hole so that the top part is guided through the motor, while the bottom part goes over the electronics.

I'd be vastly interested in your results, but if you're more interested in getting into the air and flying, then a motor change or a fan may get you results quicker.

Tim,
Your idea has merit!  I kept thinking that I would need to have airflow from the forward side of the mounting bulkhead but your way shows that i don't.  It'll be tricky to make one but it is worth consideration.  Thanks.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline John Cralley

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1228
Re: Help with Motor Overheating!
« Reply #12 on: July 03, 2015, 05:02:21 PM »
I like Tim's idea. Might be tough to fabricate at this point.
John Cralley
Scratch Built - Often Re-kitted!!!
AMA 52183
Central Illinois

Online Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 11124
Re: Help with Motor Overheating!
« Reply #13 on: July 03, 2015, 05:55:59 PM »
Tim,
Your idea has merit!  I kept thinking that I would need to have airflow from the forward side of the mounting bulkhead but your way shows that i don't.  It'll be tricky to make one but it is worth consideration.  Thanks.

I hope it works, because unless someone else disproves it it'll be the first thing I'll try if I go electric!  The "ring around the spinner" idea probably can't be beat for efficient cooling, but man I just don't like the looks.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Darkstar1

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 321
Re: Help with Motor Overheating!
« Reply #14 on: July 03, 2015, 10:14:07 PM »
Crist.
What size is the spinner and are there any holes at the motor mount to allow air to pass?
Later,
Evolve or get left behind!

Online Brent Williams

  • 2018 Supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 716
  • Making America Fly Stunt Again!
    • Fancher Handles - Presented by Brent Williams
Re: Help with Motor Overheating!
« Reply #15 on: July 03, 2015, 11:11:43 PM »
I copied this pic off of Crist's build thread.  Just thought seeing this view of the nose construction might be of assistance in the troubleshooting process.



Laser-cut, "Ted Fancher Precision-Pro" Hard Point Handle Kits are available again.  PM for info.
https://stunthanger.com/smf/brent-williams'-fancher-handles-and-cl-parts/ted-fancher's-precision-pro-handle-kit-by-brent-williams-information/

Offline Keith Renecle

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 804
Re: Help with Motor Overheating!
« Reply #16 on: July 04, 2015, 12:28:05 AM »
Hi Crist,
The 2826 series are quite small and tend to get hot, but remember that the heat comes from the inner core. Igor is flying his Max Bee that is bigger than your model with the AXI 2826/13, and his motor mount system includes a heat sink that gets rid of a lot of the heat from the core. You can see this from the photos below. This is a great idea, but of course his motor is rear mounted.

Kim Doherty's Shockwave stunter, had a few holes on the top of the nose to get air into the motor that was mounted like yours. I tried this on my old Electron with the MVVS 6,5/910 motor also mounted that way and measured a small difference in temperature. The suggestion of a fan on the rear of the motor could also work. The Cobra is a pretty close copy of the AXI 2826 series so maybe their fan will fit your motor. I even tried a fan made from thin aluminium and epoxied it onto the prop boss in front of the motor just to get the dead air flowing and it also makes a bit of difference. Igor's idea is a much better way, but then your nice neat snout will need some surgery. I hope you get it right!

Keith

Keith R

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #17 on: July 04, 2015, 01:38:45 PM »
Crist.
What size is the spinner and are there any holes at the motor mount to allow air to pass?

It's a 2 inch spinner and yes, there are holes in the mounting bulkhead.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #18 on: July 04, 2015, 01:57:46 PM »
OK guys went flying this morning and gathered some hard data.  Outside air temp was 79 to 83 F.

1st flight - with spinner and no baffle.  Essentially how it was flying from previous sessions.  A good starting point.  Motor 155 F, battery 110 F
2nd flight - spinner nose cone removed.  Motor 125 F, battery 112 F
3rd flight - spinner nose cone removed and exhaust baffle installed.  Motor 117 F, battery 110 F
4th flight - spinner nose cone installed and exhaust baffle installed.  Motor 160 F, battery 115 F

Conclusions:
Cooling air through the motor worked the best.  No surprises here.
The exhaust baffle seemed to add some cooling effect when used without the spinner.
The exhaust baffle seemed to be ineffective by itself.  The increase of temp from 155 to 160 was probably the ambient air temp went up 4 degrees during testing.

One thing I did not test today was using a different prop.  Mike Scott was out flying today with his Cobra 2826/10 930Kv 4S Edge/Hubin set up in an airplane a little larger than mine but almost the same weight and his motor temps, with a tightly cowled motor and minimum exhaust air outlet was running motor temps about 105 F.  He was using an APC 12 x 6 cut down to 11 3/4 at 8900?rpm, while I'm using an APC 13 x 5.5 cut down to 12 running at 9600 rpm.  Next time out I'll try using a 12 x 6 cut down like Mike was flying.  I could be running a prop that puts too much load on the motor.  We'll see.

I appreciate everybody's input and maybe we can all learn something together getting through this.

Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Online Fred Underwood

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 477
Re: Help with Motor Overheating!
« Reply #19 on: July 04, 2015, 02:32:11 PM »
What are line lengths, lap times, and amps used/flight time on those two plane/motor/prop combos?
Fred
352575

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #20 on: July 04, 2015, 04:38:35 PM »
Fred,
I don't know what Mikes numbers are.  Mine:

Line length: 63 foot eye to eye.
Lap time: 5.3 secs
Run time is: 5 min 30 secs
MA used: @1900 to 2000
Prop: APC 13 x 5.5 cut down to 12
RPM: @9600
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Bob Hudak

  • 2017
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 410
Re: Help with Motor Overheating!
« Reply #21 on: July 05, 2015, 11:58:22 AM »
Crist,
 Bite the bullet and buy a Tru Turn Turbo Cool spinner that spins in the direction you like. The overheat will go away.
Bob
350838

Online Fred Underwood

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 477
Re: Help with Motor Overheating!
« Reply #22 on: July 05, 2015, 01:55:20 PM »
One thing I did not test today was using a different prop.  Mike Scott was out flying today with his Cobra 2826/10 930Kv 4S Edge/Hubin set up in an airplane a little larger than mine but almost the same weight and his motor temps, with a tightly cowled motor and minimum exhaust air outlet was running motor temps about 105 F.  He was using an APC 12 x 6 cut down to 11 3/4 at 8900?rpm, while I'm using an APC 13 x 5.5 cut down to 12 running at 9600 rpm.  Next time out I'll try using a 12 x 6 cut down like Mike was flying.  I could be running a prop that puts too much load on the motor.  We'll see.

I appreciate everybody's input and maybe we can all learn something together getting through this.



Crist,
It looks like you have tried the easy cooling suggestions except the turbo spinner, and have moved to the other end of the problem, heat generation.  I was hoping to see some of the variables other than just prop for comparison.  Mike's variables, particularly amps/watts and the factors contributing might be enlightening or, differences between your current plane and prior where you used the same motor, prop, batteries. 

With more weight/wing loading, might you be using more gain rpm or time in gain on the Igor setup vs Hubin and then more watts used.

Thanks, just trying to learn as you suggested.
Fred
Fred
352575

Offline Curare

  • 2014 Supporters
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 627
Re: Help with Motor Overheating!
« Reply #23 on: July 05, 2015, 05:40:28 PM »
Christ, I had similar issues with my electric chipmunk, and tried a few things to get a better idea of whats going on.

Have you tried it with the top hatch off? This will give you an idea of whether you need more exhaust area, a radical change in temp will show that, considering yours is built like mine (or should I say I copied yours almost verbatim) I think you'll find very little change.

Adding a cooling disc to the back of the motor can help create a centrifugal pump out of the the back of the motor.

Emax have them as part of the stuff you get with their GT motors, but I suspect a fine modeller like you could make one out of carbon in a few minutes.



Be careful that you don't stall the airflow out of your motor, but have a 'cooling spinner' at one end and a disc at the other, I'm pretty sure that cooling spinners acutally pull air forwards through the motor rather than let it flow through.

Greg Kowalski
AUS 36694

Online Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 11124
Re: Help with Motor Overheating!
« Reply #24 on: July 05, 2015, 06:47:00 PM »
Greg's "cooling disk" is what I had in mind when I suggested a fan.  I've seen them advertised as add-ons to various brands of motors (or you could make one, of course).

I really don't think you need a huge amount of flow through the motor -- when it comes to forced-convection cooling, a very little bit will often go a long way (and if you need heroic measures, that probably means that you need a different motor!).
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Fred Underwood

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 477
Re: Help with Motor Overheating!
« Reply #25 on: July 05, 2015, 08:16:26 PM »
Fred
352575

Offline Curare

  • 2014 Supporters
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 627
Re: Help with Motor Overheating!
« Reply #26 on: July 05, 2015, 09:52:25 PM »
well, would you look at that!

Hacker has been doing this on their A50 series motors for a while.

As a bit of an academic aside, I did a whole bunch of research into motors after I cooked three in succession.

What I found is that most motors (hacker included) all use .025mm or similar windings as this is what the winding machines use. To get enough current through the run multiple strands, to have enough sectional area for the winding.

This is cheaper, but not necessarily efficient. Overlapped windings will build up heat, but not a great deal of torque. More expensive motors are usually built with windings that have a coating that will withstand greater temperatures before they burn, and usually that's at a temperature where the magnets can be permanently damaged from heat buildup.



In an ideal world, use of heavier guage wire, would allow for a better wind, (no overlaps or odd bunching), which in turn should mean a bit more cooling air through the stator. Innov8tive used to sell motor kits, and I've thought about winding my own motors to make more efficient, stronger motors out of smaller lighter motors, that would have otherwise burnt out at high loads.


Greg Kowalski
AUS 36694

Offline Darkstar1

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 321
Re: Help with Motor Overheating!
« Reply #27 on: July 06, 2015, 08:56:03 AM »
Crist, check Your PM.
Later,
Evolve or get left behind!

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #28 on: July 06, 2015, 09:07:16 AM »
Crist, check Your PM.

Answered back.  Thanks.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #29 on: July 06, 2015, 08:58:39 PM »
Crist,
It looks like you have tried the easy cooling suggestions except the turbo spinner, and have moved to the other end of the problem, heat generation.  I was hoping to see some of the variables other than just prop for comparison.  Mike's variables, particularly amps/watts and the factors contributing might be enlightening or, differences between your current plane and prior where you used the same motor, prop, batteries. 

With more weight/wing loading, might you be using more gain rpm or time in gain on the Igor setup vs Hubin and then more watts used.

Thanks, just trying to learn as you suggested.
Fred

Fred,
Mike is using the 2826/12 930Kv motor with a 4S battery turning around 8600 to 8900 rpm.  If I recall correctly.  He is using a Castle Edge Lite 50 ESC with a Hubin timer.  I suspect my Igor set up demands a little more of the motor because of it being an accelerometer too.  Though not enough to cause the overheating problem I'm having.
Later on I'm going to try the APC 12 x 6 prop around 8900 rpm (5.3 sec laps) just to compare it to what I'm running now.  I could put in my Phoenix 45 and Hubin timer too, if I wanted too.  Again just as a comparison.  What I eventually will do is probably go to the 3515 series motor.  It'll fit in with little problem.  The other full fuselage plane that I have also has a Cobra 2826 with the Phoenix 45 Hubin timer and a 5S battery and the motor runs hot in it also.  Hence when I wanted to build the L-40 I widened the fuselage 3/8 for increased airflow.  Now I understand that the 2826 motors run hot.  If I had known that before I started the L-40, then it would have gotten the 3515 form the get-go.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #30 on: July 06, 2015, 09:02:38 PM »
Christ, I had similar issues with my electric chipmunk, and tried a few things to get a better idea of whats going on.

Have you tried it with the top hatch off? This will give you an idea of whether you need more exhaust area, a radical change in temp will show that, considering yours is built like mine (or should I say I copied yours almost verbatim) I think you'll find very little change.

Adding a cooling disc to the back of the motor can help create a centrifugal pump out of the the back of the motor.

Emax have them as part of the stuff you get with their GT motors, but I suspect a fine modeller like you could make one out of carbon in a few minutes.



Be careful that you don't stall the airflow out of your motor, but have a 'cooling spinner' at one end and a disc at the other, I'm pretty sure that cooling spinners acutally pull air forwards through the motor rather than let it flow through.



Greg,

I have a Cobra cooling fan that will the motor.  I could try that but I'm not convinced that it will do much help.  I'll bring it along next time out and try it.

I haven't tried flying with the hatch off.  something else to try, again just for some comparisons.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #31 on: July 06, 2015, 09:04:50 PM »
Hi Crist,
The 2826 series are quite small and tend to get hot, but remember that the heat comes from the inner core. Igor is flying his Max Bee that is bigger than your model with the AXI 2826/13, and his motor mount system includes a heat sink that gets rid of a lot of the heat from the core. You can see this from the photos below. This is a great idea, but of course his motor is rear mounted.

Kim Doherty's Shockwave stunter, had a few holes on the top of the nose to get air into the motor that was mounted like yours. I tried this on my old Electron with the MVVS 6,5/910 motor also mounted that way and measured a small difference in temperature. The suggestion of a fan on the rear of the motor could also work. The Cobra is a pretty close copy of the AXI 2826 series so maybe their fan will fit your motor. I even tried a fan made from thin aluminium and epoxied it onto the prop boss in front of the motor just to get the dead air flowing and it also makes a bit of difference. Igor's idea is a much better way, but then your nice neat snout will need some surgery. I hope you get it right!

Keith



Keith,
Thanks for the information.  Stay tuned for further experiments of different things to try just for comparison.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #32 on: July 06, 2015, 09:05:44 PM »
Crist,
 Bite the bullet and buy a Tru Turn Turbo Cool spinner that spins in the direction you like. The overheat will go away.
Bob

I know, but at about $50 each..................
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Igor Burger

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 2000
Re: Help with Motor Overheating!
« Reply #33 on: July 06, 2015, 10:37:46 PM »
what about this?





it is standard axi accessory called COOLER FOR AXI 2820 & AXI 2826 order no. COOL1

Online Brent Williams

  • 2018 Supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 716
  • Making America Fly Stunt Again!
    • Fancher Handles - Presented by Brent Williams
Re: Help with Motor Overheating!
« Reply #34 on: July 07, 2015, 01:31:24 AM »
The vented spinners from Bondaero are much less expensive.  £5.99 + shipping from the UK. 
I am not sure if they have different options for the direction of rotation.

http://www.bondaero.co.uk/Vented_spinner/p1085152_10410725.aspx



Laser-cut, "Ted Fancher Precision-Pro" Hard Point Handle Kits are available again.  PM for info.
https://stunthanger.com/smf/brent-williams'-fancher-handles-and-cl-parts/ted-fancher's-precision-pro-handle-kit-by-brent-williams-information/

Offline RC Storick

  • Forum owner
  • Administrator
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 11748
  • The finish starts with the first piece of wood cut
    • Stunt Hangar
Re: Help with Motor Overheating!
« Reply #35 on: July 07, 2015, 02:20:11 AM »
On the turbo spinner shown I am not sure the back plate would let much air through without filing some kind of impeller vane into it. Flat solid things spinning at high RPM tend to block air. It would act just like a motorcycle spoke wheel at speed.
AMA 12366

Offline Curare

  • 2014 Supporters
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 627
Re: Help with Motor Overheating!
« Reply #36 on: July 07, 2015, 05:39:43 PM »
I can't remember where I read it, but someone did a bit of experimentation on spinners, and found that those style of spinners actually work best when the slot for the prop is large, and turns the whole spinner into a centrifugal pump, in doing so it actually draws air back to front.

If you want to have air go front to back, you really need a turbo spinner, like this:


..and have no or very small prop cutouts, as they will bleed the high pressure in the spinner off, and reduce your cooling efficiency. Cooling air should be high pressure and low velocity to do it's job properly.

The other way to do it, is Dennis Adamasin's style, with an opening around the outer edge of the spinner. Or no spinner.

Greg Kowalski
AUS 36694

Online Fred Underwood

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 477
Re: Help with Motor Overheating!
« Reply #37 on: July 07, 2015, 07:32:30 PM »
The Turbo Tru Turn claims to be tested to work in lowering temperatures.  HobbyKing has the plastic ones similar to above in the international market, so easy enough to obtain and test before and after temperatures.

Lucien at Innov8tive responded to my temperature question - "When I do the testing on the motor, I do not like to see the core of the motor exceed 160˚ F.  That is the point where I call the “Max Current Point” on the Cobra motors during my prop tests.  The “Can Temperature” will typically be about 30˚ F cooler than the core temperature."  and "The magnets used in the motors are rated for 150˚ C (302˚ F) but you really never want to get them that hot.  Likewise, the insulation on the winding wire is rated for the same temperature, but you can get localized heating on the inside strands of the wire, closest to the stator core, that can be significantly hotter than the core itself."  "If a motor is getting that hot, then you either do not have enough cooling, or you are simply pushing the motor too hard for the application."

In 2013 when I was looking at motors, I asked about the 2826-12 vs the 3515-18.  Lucien's reply - "Of the two motors you asked about, the 2626-12 actually can handle more power than the 3515-18 motor can.  If you needed more power than the 2826-12 motor provides, I would suggest the Cobra 3520-14 instead.  It is 1-1/2 ounces heavier, but would be able to produce more power than the 2826-12 motor does."

Looks like a "can temperature" of <130F is the goal, so more motor or more cooling, though that isn't surprising information and doesn't solve the current issue, pun intended.
Fred
352575

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #38 on: July 07, 2015, 08:42:47 PM »
what about this?





it is standard axi accessory called COOLER FOR AXI 2820 & AXI 2826 order no. COOL1

Igor,
Looks a lot like the cooling fan from Cobra.  I'll try one in August.  Thanks for the info.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #39 on: July 07, 2015, 08:44:24 PM »
The vented spinners from Bondaero are much less expensive.  £5.99 + shipping from the UK. 
I am not sure if they have different options for the direction of rotation.

http://www.bondaero.co.uk/Vented_spinner/p1085152_10410725.aspx





Brett,
Interesting spinners!  I'll look further into these.  Thanks.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #40 on: July 07, 2015, 08:46:24 PM »
Greg,
Not sure what to make about what you said about spinners and airflow direction.  ???
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #41 on: July 07, 2015, 08:49:34 PM »
Fred,
Good info on motors.  130F is a good target temp.  I'll probably go with the larger Cobra 3515 motor.  I don't want to go 1 1/2 oz heavier till I at least try the 3515 motor. 
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Target

  • C/L Addict
  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1767
Re: Help with Motor Overheating!
« Reply #42 on: July 07, 2015, 09:33:55 PM »
Do you have the 2826/10, or the 2826/12? The 10 is 930kv the 12 is 760kv...
Here is the prop data chart, which I'm certain you have looked at, but on 5S for the 12 wind it shows the 11x5.5 being the ideal prop.
http://innov8tivedesigns.com/images/specs/Cobra_2826-12_Specs.htm

The other question that comes to my mind is if the ESC has a different timing setting that might effect the run of the motor?

I'm bummed that you are having these issues. And I hope that you get them worked out.

R,
Chris
Regards,
Chris
AMA 5956

Offline Robertc

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 273
Re: Help with Motor Overheating!
« Reply #43 on: July 10, 2015, 10:45:15 AM »
Crist, I would be very interested in the results just by changing to Mike's prop.
Any chance you and Mike could do that?

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #44 on: July 10, 2015, 05:31:16 PM »
Crist, I would be very interested in the results just by changing to Mike's prop.
Any chance you and Mike could do that?

Yup, but it will be next month till we get a chance.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #45 on: July 21, 2015, 10:17:09 PM »
I ordered a Cobra 3515/18 740Kv motor along with a fan.  More testing later on in August.  Stay tuned.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline NED-088

  • 2017
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 247
    • Heartstrings
Re: Help with Motor Overheating!
« Reply #46 on: July 23, 2015, 01:26:53 AM »
Hi Crist,

I've been using this vented type of spinner on my new model from day one.
I got it from HK: [url=http://www.hobbyking.com/hobbyking/store/__58222__Turnigy_Turbo_Spinner_51mm_Red.html]this type of spinner [/url] But just like the bondaero, the aeronaut, etc. they're all made by Gemfan: http://www.gemfanhobby.com/Product/Main/En/3e414cea-154d-42a6-a640-a4790179e223
I'm running a Torcman NT-350Z with built on extractor fan, combined with the air intake through the spinner seems to do the job. Can touch the motor after flight. The cooling exhaust in the sides are mainly for the ESC, that's sitting in the 'attic'.
I'm following the road of a low (7800) revving , larger (13x6.5) prop to establish enough thrust and so far this combination outperforms my earlier (2006) experiments with an AXI 2826 and a 12x6 Using ~2400 mAh for a 5'30" run time.




'If you think there's something about my English, you're right. I'm Dutch... '
But I DO play Stunt and I DO fly Bluegrass.

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #47 on: July 23, 2015, 06:19:00 PM »
Bruno,
Thanks for the info.  I'll look into getting one of those spinners. 
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt

Offline Paul Walker

  • Charter Member
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 1258
Re: Help with Motor Overheating!
« Reply #48 on: July 24, 2015, 10:02:44 AM »
Crist,
I ran Eflite32's for about 3 years. They ran at 140 degrees F. PERIOD.
At one time I thought that was too high, and set about to cool it. I put in baffles, ran a vented spinner, ran with no spinner, no cowl, etc. The motors were all rear mounted (because there were different planes), and all ran at around 140 degrees no matter what I did. I gave up and just lived with it. The result, I ran a single motor for over 2 years with no issues until the bearings finally went. It had maybe 600 to 700 flights on it. I don't think that was too bad.

I now use the Cobra 3520 and it runs cooler. But is that going to make it last longer???

If you are in the 130 to 140 range, I would not worry about it.

Offline Crist Rigotti

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 3177
  • Electric - The future of Old Time Stunt
Re: Help with Motor Overheating!
« Reply #49 on: July 24, 2015, 12:03:22 PM »
Thanks Paul!  I'll install the new cobra motor and if it's 130-140 degrees I'll be a happy camper and move on to doing some serious trimming.
Crist
AMA 482497
Waxahachie, TX
Electric - The Future of Old Time Stunt


Advertise Here
Tags:
 


Advertise Here