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Help me figure out what went wrong

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Old 08-09-2012, 09:40 AM
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THRL-CKER
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Default Help me figure out what went wrong



Yesterday I lost control of my 1/4 scale Patty Wagstaff and it went in hard.

It was the third flight of the day, and everything had gone well. After making a low fast pass down the runway I pulled up and started to make a left turn. At about 100 feet AGL it went into a violet spin and death roll. The plane has a 50cc gas engine and will clime straight up all day long.

It went in on its nose and right wing tip, the tail section was not damaged. It has dual jr digital coreless servos on rudder and elevator. When I walked up on it there was a clicking sound coming from the rudder servos . All other servos were working, but both of the rudder servos are stripped out.

Prior to this trip to the field one of the rudder servos was found to have the leads cut and had been soldered back together and covered with heat shrink.

How the rudder servo wires got cut in the first place is a mystery, but I assume it was during a repair for when the horizontal stab was damaged with an encounter with a fence while taxiing



I will examine the rudder servo wiring today, but could a short in one servo cause the two servos to "fight each other" and cause the crach?

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Old 08-09-2012, 01:07 PM
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daveopam
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Default RE: Help me figure out what went wrong

I don't know if they would fight each other, But if they are on a Y harness the bad wires could cause a signal issue. It could make them both go full deflection and cause the snap. If they are on separate channels this would be much less likely. But would this strip the gears??? I would look more toward rudder flutter. The one servo with the bad wires could have went dead putting all the load on the other servo. The high speed pass could have over loaded it and let it flutter. While a hard hit can strip servo gears it's not common on a rudder. I would think they were stripped before it crashed. If they were stripped prior, than what stripped them? Even if one servo were strong enough to strip the other one, that's only one set of stripped gears not two.
Just my humble opinion.

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Old 08-10-2012, 04:05 AM
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Default RE: Help me figure out what went wrong

What model JR servos on the rudder?Plastic or metel geared?

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Old 08-10-2012, 09:11 AM
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Default RE: Help me figure out what went wrong


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ORIGINAL: THRL-CKER


Prior to this trip to the field one of the rudder servos was found to have the leads cut and had been soldered back together and covered with heat shrink.

When you found the cut leads, did you insure that they were not shorting under movement? Were you moving the transmitter controls when you heard the rudder servos clicking when you walked up on it after the crash?
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