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Old Jul 13, 2012, 08:20 PM
Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
1,835 Posts
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Is it junk, or do I just have it set wrong?

I have a bone stock Chinese 70mm EDF F-18. I love it. Yes, it's cheap and doesn't fly as rock steady as my Horizion Hobby stuff, but she's fast and is the biggest attention getter at the field.

But there's one thing about it that has always bothered me, and today nearly caused a crash. When I am flying and turn the throttle off, when I push the throttle back up again it often takes a second or so for the fan to come back on. I was landing today and a sudden gust of wind caused my F-18 to slow abruptly, and it stalled about 20 feet off the ground on final approach. I hammered the throttle but the fan didn't come back on until it was about 3 feet above the ground. I barely got it back up before it crashed.

So, do I have the ESC set wrong, or is it just cheap junk? The airplane flies great and is very fast for a stock setup, but it just has that one glitch.

Thanks!
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Old Jul 13, 2012, 10:56 PM
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yorkiepap's Avatar
SW PA
Joined Aug 2010
541 Posts
Hey Dave,
You have to remember that an EDF takes a few seconds to spool up to thrust rpm. It is not instantaneous. The EDF pilots I've seen "never" turn "off" their EDF's to "0" throttle.

Denny
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Old Jul 13, 2012, 11:20 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,158 Posts
Some ESC'S also have a setting for how fast the ESC responds to throttle changes. Check your instructions.
The Turnigy Plush ESC'S have a Start Up mode adjustment. Normal, slow and super slow.
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Old Jul 14, 2012, 09:42 AM
Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
1,835 Posts
Ok thanks. There's no build up of thrust. What I mean is the electric motor is off completely. When I hit the throttle, it stays off for a second or so before it comes on. If I keep the motor on but at very low RPM, it will spool up normally.

It just seems weird because on my prop planes I turn the motor off all the time for stalls and what not, and the motor comes back on immediately when I push the throttle with no hesitation. My other EDF models do the same. But this one hesitates. The instructions don't have anything in them about this, so I'm not sure what to do.
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Old Jul 14, 2012, 09:43 AM
Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
1,835 Posts
Oh yeah, if the motor is on, RPM changes are immediate. If I go from, say 10% throttle to 50% throttle, it changes instantly. But 0% throttle to any% throttle takes a second or so.
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Old Jul 14, 2012, 09:56 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
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Check your ESC for the Start Up setting.
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Old Jul 14, 2012, 11:14 AM
Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
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How do I do that? Thanks!
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Old Jul 15, 2012, 06:05 PM
Space Coast USA
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Space Coast
Joined Oct 2000
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What is the brand and model of your ESC?
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Old Jul 15, 2012, 07:23 PM
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United States, OR, Portland
Joined Jan 2008
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Or just don't ever go to 0 throttle
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Old Jul 15, 2012, 07:46 PM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
12,521 Posts
Sounds like the ESC is just dumb. You may be able to program out the problem, but maybe not. I had an ESC that would occasionally spool the motor up from zero very very very slowly, like so slowly you could barely tell it was spooling up. This seemed to be quite random; very often it would just crank right up.

I'd say just replace the ESC before it actually causes a crash. A new ESC is cheaper than a new plane.
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