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Old Jan 28, 2007, 05:33 PM
kids ate my heli budget
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Auckland, New Zealand
Joined Feb 2005
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I have an Axi 2820/10 in a helicopter but was never impressed with the power. It seemed to struggle a lot under load and ran very hot. It was very efficient though.
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Old Jan 28, 2007, 09:02 PM
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Concord, MA
Joined Jun 2002
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I think for sheer power at a given weight, a higher rpm motor geared down is going to put out more than a slower motor, but the gearbox adds some load, and weight too. I find the gearboxes vibrate loose and strip gears if not set up right, slow start and stop too. The outrunners are RELIABLE.

If you have a heat build up, that is probably inevitable as a result of running a lot of power through the motor. A larger one, EG more mass will heat up more slowly. And if one is less efficient, the power that doesn't go into output probably gets changed to heat. I suppose it could become vibration or noise too.

There are some motors that have a fan built in to cool them in the absence of a lot of airflow. I imagine on a heli the motor sits under a lot of stuff that blocks the airflow. The windings probably are what gets hot, and on an outrunner these are inside. The inrunners, some of which have heat sinks on the casings, the windings are on the outside where the fins are too. The part that spins is the fixed magnet part on both.

I am not a fizzicist though. I would say that 12 to 15 minutes is a long time if you are running a motor at it's limit and it's gonna get hot
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Old Jan 28, 2007, 10:07 PM
kids ate my heli budget
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Auckland, New Zealand
Joined Feb 2005
1,782 Posts
Quote:
Originally Posted by BEA flyer
I am not a fizzicist though. I would say that 12 to 15 minutes is a long time if you are running a motor at it's limit and it's gonna get hot
I think you're right. Certain motors handle it better than others. The Axi seemed particularly hot without much airflow going through it and didn't seem to like sudden changes in load. Whilst I've read in many places that it's a fantastic motor for fixed-wings. You're right that motors with fans seem to get by better in helis than without, also outrunners as a general rule run cooler than inrunners.

I think that helis really are much rougher on everything; motor, esc, servos, etc. That's just part of the appeal.

However, I'm really looking forward to building this pitts special too. It's something I've wanted since I was a kid.
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Old Jan 30, 2007, 12:55 AM
kids ate my heli budget
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Auckland, New Zealand
Joined Feb 2005
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Would a Hacker A50-10S be a good fit?
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Old Jan 30, 2007, 02:09 AM
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Hastings, Hawkes Bay, New Zealand (Aotearoa)
Joined Feb 2000
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What size prop can you run without having to seriously modify the landing gear? ie: Clearance from the prop shaft to the ground with the plane at horizontal. Get the answer to this and we can start to look at motors.

Heather
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Old Jan 30, 2007, 02:16 AM
kids ate my heli budget
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Auckland, New Zealand
Joined Feb 2005
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Okay, thanks Heather. I won't know the answer to that until I get my hands on the kit in a couple of weeks.
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Old Dec 30, 2008, 04:41 PM
kids ate my heli budget
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Auckland, New Zealand
Joined Feb 2005
1,782 Posts
So, it's been more than a couple of weeks

In between I've had a baby, built two helis, a hotliner and a slope soarer. I think I'm finally ready to begin construction. I'm out of CA again, so will head out to the shop in the next few days and get some then we'll get cracking on the build.

I'm looking forward to getting started.
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