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Old Jun 08, 2010, 03:00 AM
I'd Rather Be Flying
RCBlackSheep's Avatar
Stockton CA
Joined Feb 2009
591 Posts
Quote:
Originally Posted by feathermerchant View Post
Hey Dag you can use something like a Castle BEC at each motor and run your fans from the motor batteries. That should save wiring and you'll have the ultimate in redundancy.
This makes more sense to me cause if you isolate each motor/cooling system to each motor and only have each "Motor system" connected via the Rx, then if you do have a "motor system" failure, you may still have control over the other motors long enough to get back on the ground. Compared to having the whole cooling system powered by a central battery or batteries fail and the whole thing.... well I think we've seen enough crash videos.

In the pics you posted, the ESCs are on the firewalls just behind the motors but in the tests you have 10 AWG 65" leads between the ESCs and the motors? Am I missing something? Or just do I need to re-read some posts? What I am trying to understand is why your ESCs and wires are getting so hot in tests. Or is putting your ESCs closer to the motors your solution to the heat problem?
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Old Jun 08, 2010, 05:41 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
6,006 Posts
Quote:
Originally Posted by RCBlackSheep View Post
This makes more sense to me cause if you isolate each motor/cooling system to each motor and only have each "Motor system" connected via the Rx, then if you do have a "motor system" failure, you may still have control over the other motors long enough to get back on the ground. Compared to having the whole cooling system powered by a central battery or batteries fail and the whole thing.... well I think we've seen enough crash videos.

In the pics you posted, the ESCs are on the firewalls just behind the motors but in the tests you have 10 AWG 65" leads between the ESCs and the motors? Am I missing something? Or just do I need to re-read some posts? What I am trying to understand is why your ESCs and wires are getting so hot in tests. Or is putting your ESCs closer to the motors your solution to the heat problem?
In testing I was seeing if I could have long motor leads, but I see that was not a good idea now, first I thought having the ESC close to the battery would make the adding caps go away, but it made it very hard to mount the ESC so i could cool it, and service it, also it meant using up much of the air-intake for the ESC that would then restricted some cooling air to the motor . I now see keeping the ESC close to the motor is best, but I had to add caps now. So in my final design I think it will be as shown in the pictures, I still have a ton of testing, but think this is close.

Thanks
Dag
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Old Jun 08, 2010, 05:51 AM
Old Submariner
United States, WI, Milton
Joined Dec 2007
580 Posts
ESC Cooling

Quote:
Originally Posted by dag214 View Post
I think you will see why I feel I may need a fan on the ESC, having the ESC on the firewall with out any direct air makes me nervous. This is what I got done yesterday morning, and about an hour tonight.

Thanks, Dag
Hi Dag:

The motor/esc/cap bank installation looks very good, but doesn't the vertical mount of the ESC on the firewall sort of ask for a heat build up ?

The cooling fins of the heat sink have greatly reduced effect due to heat radiating essentially from the top surface of the the sink only. Any airflow thru the nacelle is almost creating a dead zone on the aft side of the firewall and very little flow over the sink.

Wouldn't the ESC be better placed where the cap bank is, in a horizontal position to gain maximum radiating effect and to see the most airflow ?

Tom
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Old Jun 08, 2010, 06:19 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
6,006 Posts
Quote:
Originally Posted by teeceeveecee View Post
Hi Dag:

The motor/esc/cap bank installation looks very good, but doesn't the vertical mount of the ESC on the firewall sort of ask for a heat build up ?

The cooling fins of the heat sink have greatly reduced effect due to heat radiating essentially from the top surface of the the sink only. Any airflow thru the nacelle is almost creating a dead zone on the aft side of the firewall and very little flow over the sink.

Wouldn't the ESC be better placed where the cap bank is, in a horizontal position to gain maximum radiating effect and to see the most airflow ?

Tom
Tom,
If I have the fan on the ESC I think I am fine, if the ESC is in the nacelle it makes it a huge service issue as I have to now make room for both the caps, and the ESC, and I also want to keep the ESC as close to the motor so I can get to all of it with only removing the cowling. I had originally planned on the caps and ESC in the nacelle, but the air flow in the nacelle at best only has a 8.5 square inch opening for air coming in. In my testing last year with a crude leaf blower set up I never got over a 15mph movement of air thru the nacelle. So my challenge is this, if I mount the ESC in the nacelle I will still need a cooling fan (maybe), if the ESC is on the firewall I will need a cooling fan (maybe). I know this pig will be a maintenance hog, I have to design to my best ability to service the systems, and having the ESC's in the nacelles seems to be problematical as I will have to have more hatches, and more structure to mount everything to.

But..... in the long run I may find out that I have to mount the ESC and caps in the nacelles.

Rock On!
Dag
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Old Jun 08, 2010, 06:41 AM
Registered User
Melbourne, Australia
Joined May 2006
6,407 Posts
The idea of running the fans off the flight battery via an sbec makes sense to me for several reasons including that you only need the fans running when the ESC/motor have power connected and don't want them running when your Rx is powered for benchwork/setup/ground testing.

I would not choose a CC BEC as they don't have a good reputation for reliability when running from more than a 3S source. My choice would be to use a DimensionEngineering ParkBEC. You would also get a small saving in cabling complexity and weight by eliminating the wiring harness from the RX power to the fan.
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Old Jun 08, 2010, 08:43 AM
Old Submariner
United States, WI, Milton
Joined Dec 2007
580 Posts
Motor/ESC/Cap Maintenance

Quote:
Originally Posted by dag214 View Post
Tom,
If I have the fan on the ESC I think I am fine, if the ESC is in the nacelle it makes it a huge service issue as I have to now make room for both the caps, and the ESC, and I also want to keep the ESC as close to the motor so I can get to all of it with only removing the cowling. I had originally planned on the caps and ESC in the nacelle, but the air flow in the nacelle at best only has a 8.5 square inch opening for air coming in. In my testing last year with a crude leaf blower set up I never got over a 15mph movement of air thru the nacelle. So my challenge is this, if I mount the ESC in the nacelle I will still need a cooling fan (maybe), if the ESC is on the firewall I will need a cooling fan (maybe). I know this pig will be a maintenance hog, I have to design to my best ability to service the systems, and having the ESC's in the nacelles seems to be problematical as I will have to have more hatches, and more structure to mount everything to.

But..... in the long run I may find out that I have to mount the ESC and caps in the nacelles.

Rock On!
Dag
Hi Dag:

I see your point with the need for easy access to the motor/ESC/ caps. I am sure you have considered this but a re-think doesn't hurt so I will offer the following.

I know the project has been long and circuetous but at this point with the B,S&T and huge $$$$ investment- how about building a "power module".

Motor/ESC/Cap bank on a "sled".

Mount the motor to a sub-firewall with a piece of 5-ply horizontal behind the sub-firewall with ESC on top and Cap bank on the botton. Sub-firewall held to nacelle firewall by four 1/4 X 20 socket head grade 5's into blind nuts.

For maintenance, remove spinner, sub-spinner and prop to gain access to the socket head screws and withdraw the power module.

Anyway more food for thought. Way back, when I suggested the one piece fuselage and her own trailer it possibly re-ignited your original thinking in this direction and walla, the rest is history.

Tom
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Old Jun 08, 2010, 09:24 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
6,006 Posts
Quote:
Originally Posted by teeceeveecee View Post
Hi Dag:

I see your point with the need for easy access to the motor/ESC/ caps. I am sure you have considered this but a re-think doesn't hurt so I will offer the following.

I know the project has been long and circuetous but at this point with the B,S&T and huge $$$$ investment- how about building a "power module".

Motor/ESC/Cap bank on a "sled".

Mount the motor to a sub-firewall with a piece of 5-ply horizontal behind the sub-firewall with ESC on top and Cap bank on the botton. Sub-firewall held to nacelle firewall by four 1/4 X 20 socket head grade 5's into blind nuts.

For maintenance, remove spinner, sub-spinner and prop to gain access to the socket head screws and withdraw the power module.

Anyway more food for thought. Way back, when I suggested the one piece fuselage and her own trailer it possibly re-ignited your original thinking in this direction and walla, the rest is history.

Tom
Sound really cool, and I would go that route if it did not add more than .75 ounces, buy at this point Velcro will hold the caps in, red RTV the fan to the ESC, and 3 servo screws will hold the ESC on.

Great idea, but weight is everything on this bird.

Rock On!

Dag
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Old Jun 08, 2010, 09:37 AM
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ErcoupeEd's Avatar
Joined May 2004
1,516 Posts
Dag, I have been looking at your pictures of the ESC's and the CAP's on the mounting board they are on.
Okay so you understand what I am thinking, as your ESC's are laying there facedown with the fans on top.

Imagine the ESC's setting on top of ( mounted) to a an additional piece of aluminum slightly larger in diameter( perhaps a circular like a large coin) which would help absorb part of the heat instead of the ESC's being mated to a piece of wood.
Just imagine your ESC's setting on something like a silver dollar to get the image in your head.
The heat could be transferred to larger area to be dissipated
Make the mounting piece as large as the mounting space allows
It should not add much additional weight either.

Here's where my idea came from. Years ago, I built a power supply for a foam cutter using a reworked power supply from an public address power supply system.
I had to use additional heat sinks, and remount the power transistors.

This would give you an additional heat sink on each ESC without hardly any gain in weight.
Mounting the ESC's to a wood firewall by themselves, the wood won't abosrb or transfer much heat, but a piece of aluminum
would, then mount the heat sink with the ESC and fan attached to it.

This coupled with the fan might just get the job done , and allow you some more flexibility as to where to mount the ESC's

You could bench test one ESC this way, make a mounting plate like I am suggesting and see if it works.
Run one with it mounted to only wood, and one mounted to an aluminum heat sink plate and see what happens.

It's just an idea.

Ed
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Old Jun 08, 2010, 10:46 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
6,006 Posts
Quote:
Originally Posted by ErcoupeEd View Post
Dag, I have been looking at your pictures of the ESC's and the CAP's on the mounting board they are on.
Okay so you understand what I am thinking, as your ESC's are laying there facedown with the fans on top.

Imagine the ESC's setting on top of ( mounted) to a an additional piece of aluminum slightly larger in diameter( perhaps a circular like a large coin) which would help absorb part of the heat instead of the ESC's being mated to a piece of wood.
Just imagine your ESC's setting on something like a silver dollar to get the image in your head.
The heat could be transferred to larger area to be dissipated
Make the mounting piece as large as the mounting space allows
It should not add much additional weight either.

Here's where my idea came from. Years ago, I built a power supply for a foam cutter using a reworked power supply from an public address power supply system.
I had to use additional heat sinks, and remount the power transistors.

This would give you an additional heat sink on each ESC without hardly any gain in weight.
Mounting the ESC's to a wood firewall by themselves, the wood won't abosrb or transfer much heat, but a piece of aluminum
would, then mount the heat sink with the ESC and fan attached to it.

This coupled with the fan might just get the job done , and allow you some more flexibility as to where to mount the ESC's

You could bench test one ESC this way, make a mounting plate like I am suggesting and see if it works.
Run one with it mounted to only wood, and one mounted to an aluminum heat sink plate and see what happens.

It's just an idea.

Ed
Great idea Ed, but not sure what you mean by my ESC setting face down, The fan will be attached and blowing thru the heat sink. I am trying to keep everything "KISS" on this project. When I tested my ESC with the fan it never got above 50C, and 100C is cut off. And with 6 cells, I never got over 40C.

End the end I may end up with the ESC's in the nacelles as it might be to tight of a fit between the motor mount, and the firewall.

Thanks, Dag
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Old Jun 08, 2010, 11:24 AM
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ErcoupeEd's Avatar
Joined May 2004
1,516 Posts
Quote:
Originally Posted by dag214 View Post
Great idea Ed, but not sure what you mean by my ESC setting face down, The fan will be attached and blowing thru the heat sink. I am trying to keep everything "KISS" on this project. When I tested my ESC with the fan it never got above 50C, and 100C is cut off. And with 6 cells, I never got over 40C.

End the end I may end up with the ESC's in the nacelles as it might be to tight of a fit between the motor mount, and the firewall.

Thanks, Dag
What I meant Dag, ( I should have been more specific) is setting like they are in the picture, or "bottom down".
Instead of being fastened to a wood firewall or nacelle floor, they would set on an aluminum heat sink, or be mounted to them.
Imagine the heat sink being a bit larger than the ESC , it could be square, like the ESC, or circular, but larger in diameter so the heat could flow into it and away.
Basically Dag, the aluminum would dissipate heat better than wood would, but then mount the heat sink with screws, bolts, whatever is your choosing.
My thoughts were it would provide more redundancy in cooling, lets say should a fan fail, etc.
Possibly a bench test with one ESC on an aluminum mount vs an ESC mounted directly to a wood surface.
I don't know what the total surface area of the ESC's are you are using, but make the mounting plates perhaps twice or larger if space allows.
I'm guessing the mounting plates at approx 1/8 inch thick? Maybe less, maybe more?
Weight shouldn't add more than a few ounces if my guess is right.
I have a hot mug of coffee next to me right now , setting on a ceramic disk,
and the disk gets quite warm from absorbing the heat from the mug, another thing that gave me this idea.


Ed
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Last edited by ErcoupeEd; Jun 08, 2010 at 11:30 AM.
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Old Jun 08, 2010, 11:48 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
6,006 Posts
Quote:
Originally Posted by ErcoupeEd View Post
What I meant Dag, ( I should have been more specific) is setting like they are in the picture, or "bottom down".
Instead of being fastened to a wood firewall or nacelle floor, they would set on an aluminum heat sink, or be mounted to them.
Imagine the heat sink being a bit larger than the ESC , it could be square, like the ESC, or circular, but larger in diameter so the heat could flow into it and away.
Basically Dag, the aluminum would dissipate heat better than wood would, but then mount the heat sink with screws, bolts, whatever is your choosing.
My thoughts were it would provide more redundancy in cooling, lets say should a fan fail, etc.
Possibly a bench test with one ESC on an aluminum mount vs an ESC mounted directly to a wood surface.
I don't know what the total surface area of the ESC's are you are using, but make the mounting plates perhaps twice or larger if space allows.
I'm guessing the mounting plates at approx 1/8 inch thick? Maybe less, maybe more?
Weight shouldn't add more than a few ounces if my guess is right.
I have a hot mug of coffee next to me right now , setting on a ceramic disk,
and the disk gets quite warm from absorbing the heat from the mug, another thing that gave me this idea.


Ed
The bottom side of the ESC is designed to be set up away from touching anything with 1/8" grommets, and never gets hot to the touch when i run it, so dissipating heat from the bottom side will do nothing, I guess that is just the way it is designed.

Thanks, dag
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Old Jun 08, 2010, 12:14 PM
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ErcoupeEd's Avatar
Joined May 2004
1,516 Posts
Then I guess the fans are the best way to go.
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Old Jun 08, 2010, 12:55 PM
HAL... Open the damn doors!
jfetter's Avatar
Miramar, Florida
Joined Jul 2007
8,504 Posts
Wow, look what I started!
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Old Jun 08, 2010, 01:31 PM
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supercubman's Avatar
Slaton, TX
Joined Oct 2008
735 Posts
Dag,

Would it be possible to use the upper or lower nacelles caverns to channel air to the firewall, and then baffel the air down through the esc? You probably have already though of that, but that might possibly eliminate the need for the fan units, saving weight and power.

RO! (Rock On!)

Trey
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Old Jun 08, 2010, 01:47 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
San Jose, CA
Joined Jan 2008
27,136 Posts
Quote:
Originally Posted by dag214 View Post
Sound really cool, and I would go that route if it did not add more than .75 ounces, buy at this point Velcro will hold the caps in, red RTV the fan to the ESC, and 3 servo screws will hold the ESC on.

Great idea, but weight is everything on this bird.

Rock On!

Dag
Hi Dag...

Are you using the red RTV due to heat?? (many high heat resistant RTVs are red) Or is it an electronics compatible RTV. If the RTV smells like vinegar, please do not use it, as it has ascetic acid in it, and will corrode any electronic circuits. Dow Corning has many electronic compatible RTVs which do not have ascetic acid in them, and while most are clear or white, I know they have black, but don't know if there is a red, hence my question. They also have electronics compatible that are heat resistant, so if you are using the red due to heat, and it is not electronics compatible, you might want to look into them.

Just trying to look out for your plane my friend...

SteveT
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