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Old Jul 11, 2003, 02:41 AM
EDF Head
Haldor's Avatar
Stavanger, Norway
Joined Feb 2000
7,999 Posts
Jepe A4 goes supersonic..

Well the headline is a little exaggrerated but..

I have previously flown my Jepe A4 on a Kontronik Fun500-21 on 15x HR2600's, power HOC 900W.

I wanted some more runtime and decided to go with a slightly milder motor with more cells and installed a Fun600-18 and soldered up a 18cell pack of HR2600's. On paper these two combo's should give about the same power so expected static amps to be around 50.

First flight, good launch great speed and zoomed about for 2mins when the ESC shut down. Landed safely. Peaked the pack back home and pulled out the Whattmeter.

HOC 62A/1200W - no wonder why it was so fast...

Okay so it was the high amp/part throttle that sent the ESC into thermal shock The problem was reproduced on the ground.

Earlier, with the 500-21 motor/15cells the ESC took 57A flights without missing a beat but the ESC was also then placed inside the motortubing = a lot more cooling.
Its now inside the fuselage so I need to think of something to let it run cooler, or go with a even milder motor.....but then I wont have that impressive power...

Hmm where did I see that heatsink...
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Last edited by Haldor; Jul 11, 2003 at 02:44 AM.
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Old Jul 11, 2003, 09:40 AM
Flying Welder Pilot
Plane Crazy's Avatar
Reno, Nevada
Joined Jan 2001
1,137 Posts
Haldor is turning into a power hungry sorta guy. Must be contaguous....

On my Y/A F18 I was using the Schulze 55bo ESCs which had a heat sink on the hot side of the ESC. I would cut a rectangular hole in the duct work and mount the ESC with the heat sink fins sticking thru the duct into the airstream, using GE high temp silicone to glue it in. This worked very well.

Heat sinks and cooling seem to be a buzz word in these days of LIPO use. I am currently working on heat sinking all my ESCs to help with the longer durations of LIPOs. Cutting the shrink wrap out where the hot components are and mounting a Heat sink really does help with the cooling along with airflow. I am tempted to remove the shrink wrap from the ESC entirely and allow more open air operation.

It is interesting that motor heat is not as a big a problem in EDFs compared to paint stirrer planes due the motor being in the stream of air.

Go Haldor go.

Gordon
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Old Jul 11, 2003, 09:45 AM
Registered User
Sture Smidt's Avatar
Norge, Østfold, Moss
Joined Jan 2001
282 Posts
Haldor,

My A-4 is soon finished...

How does yours fly in terms of low speed handling?

SS
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Old Jul 11, 2003, 05:08 PM
Ductedfann's Avatar
mid west
Joined Jan 2002
668 Posts
Haldor,

Heres what I have been doing for a couple of years
CPU parts cut to fit, can't read it but 5v dc with heat gel adhesive wired off spare on rx. Oh and its brushless.
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Old Jul 11, 2003, 05:16 PM
Ductedfann's Avatar
mid west
Joined Jan 2002
668 Posts
in use 5v dc
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Last edited by Ductedfann; Oct 19, 2003 at 05:24 PM.
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Old Jul 12, 2003, 05:57 AM
EDF Head
Haldor's Avatar
Stavanger, Norway
Joined Feb 2000
7,999 Posts
Gordon - heatsink through ducting is what I was considering. Need to get a proper heatsink then and just do it The speed was addictive, guesstimate 120mph. I have closked it at 110mph before on 900W out of a dive - it was faster now
What doesnt turn me on is the ~3min runtime..


Sture - slow speed handling is good though keep the speed up in turns. I havent experimented yet with up ailerons to bring nose up/speed down for landings, will now however as AUW is approx 2,5kg.

Thx DF for the pics - I have a plan....
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Old Jul 14, 2003, 08:05 PM
EDF Head
Haldor's Avatar
Stavanger, Norway
Joined Feb 2000
7,999 Posts


Remotored the A4 tonite: Fun600-18 out , 600-15 in.
Also located a fan equipped CPU chip from a old graphic card which I added to the Beat60. Power to the fan is taken from the rx. Ideally I should have 12V for the fan but on the 18cell pack the fan gets too hot, atleast the 5V tap get it moving.

I'll try to locate a better shaped heatsink for it so I can expose it to the intake airflow.

Flighttest tomorrow I hope, will do powerreadings of this combo also...
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Old Jul 14, 2003, 08:51 PM
Acme Powered!
Joe Elston's Avatar
Orange,CA
Joined Jul 2000
4,040 Posts
Heat Sinks

Haldor, looks interesting. I am planning to go to the computer mega store where they have everything. And pick up some heat sinks and some heat transfer epoxy. Then I will take the shrink off the hot side of my Hacker Master 77 and glue the sink on. I then plan to cut a hole in the exhaust ducting of my El Bandito just large enough for the sink and then I will silicone it into the ducting with some heat and electronics safe blue silicone. And hopefully that will keep my HM 77 cool for the special battery I have planned for the Bandito I will take some pictures when its done please let us know how the fan works out.
Joe
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Old Oct 17, 2003, 11:21 AM
Registered User
Joined Oct 2003
37 Posts
Hello guys,
Im kinda new to the matter but what about using the scale ram air inlets of the fighters to cool the controllers?
I remember the f-16 and a-4 have some around the real ones i mean.
Have fun
Ivan
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Old Oct 17, 2003, 01:24 PM
Lithium Member
Herb's Avatar
Irvine, Calif USA
Joined Feb 1999
12,169 Posts
Re: Jepe A4 goes supersonic..

Quote:
Originally posted by Haldor
... when the ESC shut down. Landed safely. ... Hmm where did I see that heatsink...
When I set mine up I installed a Jeti/Hacker Master 77 opto controller in mine for safety. Never had a problem, at 50+Amps on 20 cells it just gets barely warm after a flight. A little bit of airflow at 100+ mph goes a long way ...

I have large cooling holes in the front. I think the Hacker Master might in fact be good to 100A for short bursts, I don't have the figures in front of me.
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Old Oct 17, 2003, 01:30 PM
Lithium Member
Herb's Avatar
Irvine, Calif USA
Joined Feb 1999
12,169 Posts
Btw there's some really tiny computer fans around ... I have one in the GE Force FX or whatever it's called 128bit video card that I bought for my son's shuttle computer, I think the fan to cool that smoking graphics processor chip is maybe one inch squared sized.
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Old Oct 18, 2003, 09:02 AM
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Arngeir Blakseth's Avatar
Molde, Norway
Joined Jan 2001
2,456 Posts
Why not cut a hole in the inlet ducting and fit the ESC heatsink plate flush with the surface? Lots of cold fresh air to cool it there.

Here's a link to my thread bout my Aeronaut Panther, see pics at top of page for ESC installation, there's room for something like this on the A-4 too?

http://www.rcgroups.com/forums/showt...r&pagenumber=4
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Old Oct 18, 2003, 10:32 AM
Lithium Member
Herb's Avatar
Irvine, Calif USA
Joined Feb 1999
12,169 Posts
... it's just that most of us (including myself) would tend to resist the idea of cutting a large square hole in that beautiful ducting - or for that matter in the fuse side, if it can be avoided ...

Also you'd have to mount securely it so you don't blow dirt & possibly metallic parts through the circuitry. Imo esc's should be delivered with optional heat sinks.

Finally some esc's have several layers of small mosfets, so cooling one side of the esc only is not going to do it.
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Old Oct 18, 2003, 12:31 PM
Ductedfann's Avatar
mid west
Joined Jan 2002
668 Posts
I had been waiting to launch possibly a line of less expensive lipo polys, they just arrived and I have not yet had a chance to test them. When I ordered these, I also ordered small fans (1"x1"x7/8"). The batteries took a while to arrive thought I have had the fans for a couple of months. I got the fans to go with the batteries. Since it seams it seems that the longer running times with the lipo polys were causing motor and esc heating, I had planned to package the batteries with the fans. But, if anyone would like a fan by itself, I do have them. $8.95 plus shipping per Ductedfann@aol.com...someday it will be on the website.
I will offer them with an onbord switch so that if you want you can turn it on/off in flight from your transmitter given you have open channel and a trans with a toggle. Currantly just plugs into open rx port/channel added plug.
Specs: brushless ball bearing, high percision, 13,000 rpm, less than 24 dba noise, 4.5 cfm @ 6 volts, 3.8 cfm @ 4.8 volts
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Last edited by Ductedfann; Oct 18, 2003 at 12:39 PM.
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