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Old May 31, 2001, 02:02 AM
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Augeredin's Avatar
Allen,Texas USA
Joined Dec 2000
126 Posts
When/if to retire a speed 400 ??

First post a a senior member Okay I fly my plane at least 6 flights a week. Plane now 6 months old ,same speed 400 same gunther prop. seems to run ok but how long do these last? Do they become more or less efficient with sky time?
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Old May 31, 2001, 02:10 AM
Registered User
Austin, Texas USA
Joined Mar 2001
848 Posts
These motors are cheap. That is all there is to it. The magnets, bushings and various parts are not meant to last for years and years of usage. They are designed to wear quickly, and the magnets will lose their power over time. The best judge of motor life is common sense.
I would think that you are well into the motors life. Yes, it may still work. But work well? That is another question.
It may appear to work fine, but since the performance will slowly degrade, this may not be obvious. Chances are very good that it will die sooner or later. Without measuring the AMP draw and RPM (compared to a new motor), there is no accurate way to measure the performance degredation.
Try spending around $7 on a new Speed 400 motor. The performance increase may suprise you, and the old motor may be worse off then you expected. If not, use the old motor and you have that $7 replacement when the day comes.
There are exceptions, and many may post about their 2 year old Speed 400 that keeps on going. But for $7, why cheat yourself out of the full performance possible?

Shawn
Eflightpower.com
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Old May 31, 2001, 02:20 AM
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Augeredin's Avatar
Allen,Texas USA
Joined Dec 2000
126 Posts
If I were to replace it with speed 400 ball bearing motor would I need to more than the 14 amp ESC i currently have ? would the perfomance/duration improvment be Noticable? Brushless would be better but I am currently $$$$Limited$$ although I have seen some brushless with ON OFF controllers that seemed reasonable. I generaly fly full open to 0% anyway.
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Old May 31, 2001, 02:52 AM
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Weilbach, Germany
Joined May 2001
2,470 Posts
I guess my Twinstar was one of the first out of the mould. It is 3 years old, has the original 400's, the original GŁnther props and has over 450 flights on it.
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Old May 31, 2001, 12:31 PM
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Larry Dudeck's Avatar
Williamsville, NY, USA
Joined Sep 2000
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The ubiquitous S400 motor is not originally designed for R/C flying. They are manufactured by the millions for a large variety of uses. Many are used in the auto industry.

When operated at the specified voltage in their intended purpose these motors will last for years. It's only when these motors fall into the hands of e-fliers do they experience shortened life spans.

I think it is safe to say their life span is indirectly proportional to the current. As long as the current isn't so high to cause the brushes to arc, the motor should last indefinitely. At low current rates the bushings will probably fail first. Bushing failure can be minimized by an occasional drop of oil and balanced props.

On the other hand, operating these motors in their intended fashion will result in really boring performance at best.

So keep a few spare motors around, pour on the amps and enjoy
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Old May 31, 2001, 12:37 PM
tic
thunderscreech
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New Cumberland, PA. US
Joined Dec 2000
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400 plus flights on my 7.2v speed 400.. no noticeable performance degradation, but I may replace it soon anyway, just for the heck of it.
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Old May 31, 2001, 02:46 PM
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Alleroed - Denmark
Joined May 2001
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Larry wrote: "....When operated at the specified voltage in their intended purpose these motors will last for years. It's only when these motors fall into the hands of e-fliers do they experience shortened life spans......"

I'm currently building a Heli using Graupner's Uni-Expert-Mechanic-Elektro. The motor is a UltraBrush 3300-serie designed for 20Volts. Graupner/JR recommend this motor to be powered with 36volt for heli use.
If Larry is right, then this motor has a short lifespan or what?

/Jesper
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Old May 31, 2001, 03:08 PM
Motors beat engines!
Milwaukee Wisconsin, United States
Joined Feb 2001
4,564 Posts
I just put in my third 6v400 in my skyscooter. I thought perhaps the esc was'nt working right causing power to really be poor, but tried out a new 6v 400 today 3:1 with 9x7 prop on the rs 1600 pak and performance is back to good again.
Its funny, the old motors seem to run fine, except they just don't have the power anymore. I'm assuming the magnets have weakened.
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Old May 31, 2001, 03:29 PM
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Austin, Texas USA
Joined Mar 2001
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Quote:
Originally posted by ChrisP:
I guess my Twinstar was one of the first out of the mould. It is 3 years old, has the original 400's, the original GŁnther props and has over 450 flights on it.
I knew a guy with an old truck that was well over 3 decades old, had the original engine and had over 450,000 miles on it.

It would run, but not as well as a new one.



Shawn
Eflightpower.com

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Old May 31, 2001, 04:47 PM
tic
thunderscreech
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New Cumberland, PA. US
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all else being equal.. a 6v speed 400 will wear out before a 7.2v
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Old May 31, 2001, 05:08 PM
ὅπερ ἔδει δεῖξαι
Gerald's Avatar
Joined May 2000
3,339 Posts
Quote:
Originally posted by tic:
all else being equal.. a 6v speed 400 will wear out before a 7.2v
That's why all else SHOULDN'T be equal. Each motor should be powered according to its optimal configuration.
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Old May 31, 2001, 05:37 PM
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Larry Dudeck's Avatar
Williamsville, NY, USA
Joined Sep 2000
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I have an EJF EDF400 which is powered by a 4.8 v S400. On 8 cells, that motor was good for 35 flights of about 4 minutes. Then the brushes were gone.

I've since changed motors and the pack to 7 cells so I would expect the life to be longer.

To Jesper,

That motor will have an abrieviated life span compared to its design point. But even at that the life span may be adequate for a couple of hundred flights or so. On the other hand, the heli probably wouldn't fly on 20 V.

I don't think there is any harder usage of these motors than R/C flying.

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Old May 31, 2001, 05:50 PM
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Westmont, IL, USA
Joined Nov 2000
22 Posts
Is it the usage, or time (obviously both, but which prevails) that causes the magnets to weaken. I know heat is not good for magnets, but does the rotor flux destroy the permanent magnets as well?

What started this thought was wondering if the motors had a "shelf life". Buying a motor as a spare would not then be as good an idea as buying one when the flight motor poops out.

-Edd
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Old Jun 01, 2001, 12:03 AM
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Folsom,Ca,USA
Joined Apr 2001
992 Posts
Edd
re: magnets. Ferrite magnets field strength will decrease with heat, as long as the "Curie point" is not exceeded the strength will come back when they cool down.
Once the "Curie point" temperature is exceeded ( even for a very short time) they never come back to full strength.

I don't think that the field windings will hurt them, and I have never heard of a shelf life problem. As far as I know, heat is the enemy.

Dave
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