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Old Jun 05, 2001, 05:40 PM
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esox's Avatar
Eugene, Oregon
Joined May 2001
123 Posts
when I add power, I have no rudder / elevator control

Plane is a Super Cub from Hobby Lobby.
Graupner S400
Mini Olympus Gear Drive
Jeti 110 Speed Control
Hitech RCD 3500 receiver
2 HS81 servos

The rudder and elevator controls work fine until I add any more than about 25% power. Then, they move R E A L L Y slowly if at all.

I thought maybe I was getting interference from the motor, but the reciever is way aft and the ESC position doesn't change this behavior.

Any thoughts?

Sure am glad I didn't get it in the air 10 feet before I realized what was happening!

Jack Wheeler
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Old Jun 05, 2001, 05:53 PM
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yb2normal's Avatar
Broomfield, CO, USA
Joined Jan 2001
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Hate to be redundant, but what you said is exactly what it sounds like. I had the same problem on my Wingo, although in my case the ESC had shifted until it was laying against the receiver. (It was a Jeti 110).

Symptoms were exactly as you describe... push the rudder stick over, and the rudder would slowly, in fits and starts, move over to the position indicated by my stick.

Make sure all three capacitors are installed correctly on your motor, and that the capacitor between the motor terminals is not accidently touching the motor case. (negates it's effectiveness)

And as a last resort to rule out emf noise, wrap the ESC's 'hot' wire going to the receiver a couple times through a ferrite core to help supress any noise that might be overwhelming the receiver. Make sure the core is as close to the receiver as you can get it.

Good luck!
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Old Jun 05, 2001, 06:57 PM
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esox's Avatar
Eugene, Oregon
Joined May 2001
123 Posts
Capacitors? Uh oh! I didn't realize that I needed them. There was no mention of this in the instructions for the motor / gearbox combo.
I assume there is a large one that crosses the motor terminals. Where are the other two installed? Also what size capacitors do I need to buy?

Thanks for the help!

Jack
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Old Jun 05, 2001, 08:45 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,290 Posts
Bet you have the Hitec Flash AM Tx. I had the same thing happen to me. It's the Jeti 110 crapping out. The controls worked at full off or full on throttle. Any partial throttle and the controls would act like they were in slow motion. Coincidently, my prop break stopped working.

Call Hobby Lobby service and tell them. You need a new ESC.
hoppy
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Old Jun 05, 2001, 09:04 PM
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esox's Avatar
Eugene, Oregon
Joined May 2001
123 Posts
Thanks for chiming in Hoppy.
I have a Futaba Skysport4 fm TX.
I definitely have no control at full throttle- only when the throttle is less than about 20%.

Here's something weird:
When I remove the prop, I have full control at all throttle settings including full on. Put the prop back on and I get the same slow-motion movement. And when I say slow motion, I mean you have to look hard to see the movement.

How does that affect the diagnosis?

Jack
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Old Jun 05, 2001, 09:12 PM
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NE Ohio
Joined Apr 2001
39 Posts
Hi

I'm pretty sure brush arcing is a major component of EMF interference. By removing the prop, and reducing the current to 1 amp instead of 10, the interference was reduced?
I suppose if this is true, properly breaking in the motor would help also.

Of course, if it is a problem with the ESC/BEC, then maybe the lower amp draw of the propless motor would help there also.
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Old Jun 05, 2001, 09:29 PM
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Broomfield, CO, USA
Joined Jan 2001
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I agree with RedLine's theory regarding arcing.

esox, two of the capacitors will be inside the body of the motor, if it's branded by one of the 'big' e-motor guys like graupner or multiplex. If you look in the vents down by the brushes you should just be able to see the capacitors (one through each vent). Another good indicator is a thin wire snaking up out of the motor and hugging each terminal. These are generally .01 uf capacitors inside the motor. I've heard it recommended that a .047uf capacitor is the "right" size for the one that spans the terminals, but you have a little leeway here. (and by leeway I'd say a .01uf is better than none at all) If there are no capacitors at all, then you'd put one across the terminals as you noted, one from negative terminal to the motor body, and one from the positive terminal to the motor body. This is where a 40+watt soldering iron helps, as the motor body absorbs heat pretty fast and prevents a good solder bond.

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Old Jun 05, 2001, 09:29 PM
Space Coast USA
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Space Coast
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I'll bet the V to the receiver drops when the motor starts drawing the amps. I think the BEC circuit in the ESC is not working right. Mine would work just fine when I put a battery pack on the rx. Give that a try.
hoppy

Quote:
Originally posted by esox:
Thanks for chiming in Hoppy.
I have a Futaba Skysport4 fm TX.
I definitely have no control at full throttle- only when the throttle is less than about 20%.

Here's something weird:
When I remove the prop, I have full control at all throttle settings including full on. Put the prop back on and I get the same slow-motion movement. And when I say slow motion, I mean you have to look hard to see the movement.

How does that affect the diagnosis?

Jack
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Old Jun 05, 2001, 10:14 PM
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Eugene, Oregon
Joined May 2001
123 Posts
While we're on the subject, how does one properly break in a S400 type motor?

Jack
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Old Jun 05, 2001, 10:33 PM
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Texas
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http://www.ezonemag.com/pages/efaq.htm#motor15
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Old Jun 06, 2001, 12:11 AM
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esox's Avatar
Eugene, Oregon
Joined May 2001
123 Posts
Thanks for the link to the faq (duh!)

Ok, I'm breaking in the motor on a couple of D cells. This is a graupner motor, so it has the small capacitors inside the motor. I will pick up a .047uf cap to bridge the terminals outside. If this doesn't fix things, I'll assume it's the ESC and get Hobby Lobby to replace it (I hope it's not too late for that as this was a Christmas gift).

Thanks for all the help guys, I can't wait to get this plane in the air!

Jack
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Old Jun 06, 2001, 09:03 AM
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Mt. Laurel, NJ, USA
Joined Aug 2000
948 Posts
esox,

One more thing-

I've read several posts lately about various problems all related to folks using Futaba "Skysport" radios.

Do a search on it to see if there are any related issues. Seems weird. Could be the ESC. Switch to another non-Jeti brand and see it there is a problem. Them try a different receiver (if you have one).

Chris
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Old Jun 06, 2001, 05:51 PM
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Eugene, Oregon
Joined May 2001
123 Posts
I pulled another RX out of a sailplane and put it in this plane just to make sure, and lo and behold, that fixed it. :-) It did not however, fix the fact that I am new to powered flight and made the classic newbie mistake of over-controlling the plane. It was either tail heavy, or trimmed with too much up elvator and I had my hands full right from the start. I had it almost inverted within 10 seconds. By that time I couldn't catch up and she nosed in from about 20 feet up.

Oh well, I think I can piece it back together, but I believe I'll get something made of foam and practice a bit before I fly a built-up model again!

Thanks again for all the suggestions.

Jack
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Old Jun 06, 2001, 07:07 PM
Space Coast USA
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Space Coast
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JACK....T-52....No one can break it! Anybody ever break a T-52??
hoppy
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Old Jun 06, 2001, 07:28 PM
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esox's Avatar
Eugene, Oregon
Joined May 2001
123 Posts
hoppy, who makes the T-52?

I'm thinking I might buy one of those big stryo gliders at the hobby shop ($7.00) and kit-bash it into a high(ish) wing trainer. If I add trailing edge material to the wings and tail sections and straighten out the sweep, I think I'll have a flyable plane.

Jack


[This message has been edited by esox (edited 06-06-2001).]
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