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Old Jan 18, 2004, 02:15 PM
4-D traveller
glxy's Avatar
New Location
Joined Dec 2003
620 Posts
Question
How long should you fly?

Now that I can easily hover nonstop and fly my Aerohawk out of a full pack battery, Iím worried about the motor. I noticed it gets boiling hot after 3 minutes flight. Is it then better to take a break and let the motor cool down? I can oil the bearings and other moving parts, but not the brushes. How long can you fly without burning the motor too quickly?
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Old Jan 18, 2004, 02:38 PM
Registered User
Boulder City, NV
Joined Jul 2003
107 Posts
Get a heat sink if you do not already have one.
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Old Jan 18, 2004, 05:56 PM
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Fair Oaks, CA
Joined Jan 2004
28 Posts
Re: How long should you fly?

Man, I look forward to the time when my skills allow that problem!

My Aerohawk came with the stock heat sink on it -- I have added heat-conductive paste (Radio Shack or any PC supply house) for added peace of mind. With a little grinding, it looks to me like you could fit two stock heatsinks on the stock can at one time (though there's an obvious weight tradeoff).

What fuselage are you running? Some look like they would almost totally block rotor-wash from the main motor...

Randii
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Old Jan 18, 2004, 06:07 PM
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Melbourne
Joined Nov 2003
365 Posts
Aerohawk heat...

I have the same problem - I can fly out the entire Aerohawk pack though I still drift around a bit in hover. The pack lasts about 10 mins with the NiMH it came with, and after I finish flying the heatsink it too hot for me to touch for more than about 2 seconds. I know that taking the canopy off helps it cool down a bit, but I really like seeing the bird fly with it on...
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Old Jan 18, 2004, 10:06 PM
Frequent flyer
Grand Forks, ND
Joined Aug 2002
632 Posts
aerohawk similar to a piccolo? if so, you have a serious problem if it is that hot in 3 minutes! wrong size pinion or lash not set correctly on your gearing. (or something else binding)

also, the general rule of electronics, motors included, is that if you can't press your finger on it for 5 seconds, heat damage IS occuring.
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Old Jan 19, 2004, 07:26 AM
4-D traveller
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New Location
Joined Dec 2003
620 Posts
Thanks for your input, folks!

I was touching the motor shaft - the heatsink never gets that hot. I wouldn't add another heat sink. I think it gives very limited benefit for the extra weight. A far better solution is oiling the bearings and the motor shaft, but it's from the brushes where most heat is coming.

I'm using the usual Aerohawk canopy. It didn't fit new. The people making it seemed have forgotten the battery pack. I made new holes above the old ones, the canopy then fits well without interfering with the swash links.
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Old Jan 19, 2004, 10:54 AM
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Oliver BC Canada
Joined Nov 2002
189 Posts
That is really why people are going separates and brushless motors. Those stock motors are being pushed to, and beyond, their designed limits. Using heat sinks may slow, but not stop the inevitable, and that is that motor will soon be toast.
A typical brushless motor application in a Hummingbird, Aerohawk, whatever, with Li-poly batteries will fly for 20 minutes or more and barely get warm to the touch, and that is without a heat sink,,, you just don't need one.
Sure brushless set-ups cost more, but they are cool, in more ways then one, and properly maintained, they could out last hundreds of brushed motors. Factor that into your costs and you could easily turn it around and say in the long run brushed motors are more expensive.
It's kind of like the battery dilemma. Sure it's cheaper to buy deposable batteries then rechargeable, but drain your batteries a few times and buy some more and suddenly the cost of those disposable batteries is starting to exceed the cost of those rechargeable batteries you thought were too expensive.
Although in the case of brushless versus brushed motors, the case for brushless motors is much stronger because not only do you get a motor that will out last the life of many brushed motors, but you get much better performance in the way of flight times and power.
It's a win win situation, you just gota come to terms with paying a little more initially and reap the long term benefits.
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