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Aircraft Servos

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Old 12-04-2012, 07:48 PM
  #1
rayg1022
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Default Aircraft Servos

Is it common to or part of the hobby to have servos freeze up on you in mid flight and you end up throwing your plane into the ground? Just curious if this part of the sport or a freak accident?

Thanks,
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Old 12-04-2012, 09:03 PM
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Default RE: Aircraft Servos


Quote:
ORIGINAL: rayg1022

Is it common to or part of the hobby to have servos freeze up on you in mid flight and you end up throwing your plane into the ground? Just curious if this part of the sport or a freak accident?

Thanks,
I am not trying to be sarcastic but just trying to help. Could you be more specific as to the type of servos, battery type and voltage, and how they were connected to the Rx?

? I have had servos fail due to broken gears, bad Y's or extensions, too much voltage, oil or corrosion in the connectors, hinges that were binding, dirty pots, not enough torque, wrong spline on servo arm.
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Old 12-04-2012, 11:41 PM
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Default RE: Aircraft Servos


Quote:
ORIGINAL: rayg1022 Is it common to or part of the hobby to have servos freeze up on you in mid flight and you end up throwing your plane into the ground? Just curious if this part of the sport or a freak accident? Thanks,
What happened after the pieces were picked up and tested - all working AOK again or still frozen?
as in post #2:
1. If a GPmodel, then most likely the battery pack was not large enough to deliver the power required under load,
or the receiver lost signal from the TX and was sending no instructions to the servo.
2. If an EPModel, then please refer to overheated BEC under,
Electronic Speed Control - Why BEC and LVC cause most EP RX problems.
extract
<snip>"BECs are also rated by how many amps they can deliver to the receiver. The
greater the number of servos installed the greater the amperage the BEC must
deliver and the more heat it generates in the process. However, with most
integrated BECs, the higher the voltage of the motor battery pack the lower the
amperage the BEC can deliver. This is often where problems occur. It is this
heat load that leads to the need for a compromise as to how many servos an
integrated BEC can support.

For example, if the motor pack is 8.4V, then a given BEC might be able to
support 4 servos. If the motor battery voltage is higher, say 11 volts, then
the same BEC may need to be derated to handle only 3 servos. Since more heat
will be generated by the larger step down from 11 volts to 5 volts, the amp load
has to be reduced or the BEC will overheat. <snip>"
The BEC in many cheap RTFairplane kits can only handle two servo
wiithout overheating and shutting down with a 3S pack.

Much more information available under sub sections
"ESC & BEC - Setup to prevent majority of all RF Problems, Brownouts & Crashes"
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
"Servo - Alterations, Calculators, Databases, Leads, Repairs & FAQ."
below
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model & RC FAQ Web Links

Alan T.
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Old 12-05-2012, 05:18 AM
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rayg1022
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Default RE: Aircraft Servos

Wow... to much detailed info you guys are going to make my head burst... this was a alpha 40 trainer kit I been flying for about 6 mos with no problems and this last weekend was my last flight with it... everything had a 24 hour charge on it and was running fine when she was in the air when I started to make my approach for landing and was in my turn everything stopped working when I went to recover the plane I noticed that 2 of the 4 servos weren't moving like frozen so I was curious if this a common thing for this sport or a freak accident...makes me kind of nervous flying my 540 edge 3D really don't want too throw that in the ground...
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Old 12-05-2012, 05:26 AM
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Default RE: Aircraft Servos

No it's not common.
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Old 12-05-2012, 07:13 AM
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Default RE: Aircraft Servos

No, it's not common.  I have planes flying now with 20 year old servos in them. I'm not talking high dollar ones either.  Hitec HS-300's,  HS-422's, JR NES-507's, etc.  All work flawlessly.  The only servo's I've ever lost were cheap Futaba's.  I only got a couple of years out of my S-148's.  And that was because the output wore out and the servos were too sloppy to use.
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Old 12-05-2012, 07:28 AM
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Default RE: Aircraft Servos

So I have a 540 edge 3D how do I over come that fear of tossing another plane into the ground.. I know it may sound silly but theses planes aren't cheap when you have a family etc?
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Old 12-05-2012, 07:44 AM
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Default RE: Aircraft Servos


Quote:
ORIGINAL: rayg1022

So I have a 540 edge 3D how do I over come that fear of tossing another plane into the ground.. I know it may sound silly but theses planes aren't cheap when you have a family etc?
You still have not defined what radio you are using and how you are powering it. The symptoms you describe could very well be the result of the Rx going into Failsafe, for example, which would maintain power to the servos but you would have no control, as they would hold their position.
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Old 12-05-2012, 08:18 AM
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Default RE: Aircraft Servos


Quote:
ORIGINAL: BuschBarber


Quote:
ORIGINAL: rayg1022

So I have a 540 edge 3D how do I over come that fear of tossing another plane into the ground.. I know it may sound silly but theses planes aren't cheap when you have a family etc?
You still have not defined what radio you are using and how you are powering it. The symptoms you describe could very well be the result of the Rx going into Failsafe, for example, which would maintain power to the servos but you would have no control, as they would hold their position.
I'm using a dx7 with hi tech servos.in my 3D plane never had problems for 6 most of flying. The battery is rechargeable one in the receiver
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Old 12-05-2012, 11:06 AM
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Default RE: Aircraft Servos


Quote:
ORIGINAL: rayg1022 So I have a 540 edge 3D how do I over come that fear of tossing another plane into the ground..
I know it may sound silly but theses planes aren't cheap when you have a family etc?
Unfortuntely, to save money, you must spend a little time reading and updating your knowledge
bank on the overall operation of your rc system.
In particular how the various parts work and are influenced by small factors such as servo installation,
correct size of batteries to use and how to diagnose what was the cause of any jitters or unusual behaviour
which lead to crashes.
Servo - How to Diagnose Servo Failures & Repair Servo
Servo - How they work, adjust & repair tutorial
Servo - Installation - Correct Mounting & Tips for longer life.
and if using MG servo
Servo - FAQ : Metal Gear Servos - DIY Repair & Extend MG Servo Gear Life

and as in post #3 above, much more information is available under sub sections
"ESC & BEC - Setup to prevent majority of all RF Problems, Brownouts & Crashes"
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
"Servo - Alterations, Calculators, Databases, Leads, Repairs & FAQ."
below
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model & RC FAQ Web Links

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Old 12-05-2012, 11:39 AM
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Default RE: Aircraft Servos

Ray, you still didn't identify hour system or provide enough information to diagnose the problem. You said you had a DX 7 with Hi Tech servos. I am assuming you meant Hitec servos, but what kind?

In your statement: I'm using a dx7 with hi tech servos.in my 3D plane never had problems for 6 most of flying. The battery is rechargeable one in the receiver


Did you mean a DX 7 with Hitec servos in your 3D plane? Or your using a Dx7 with Hitec servos?

In my 3D plane never had problems for 6 months of flying. What does that have to do with the crash?

The battery is rechargeable one in the receiver. I have not heard of a battery that is inside the receiver.

Did the servos work after you got them home and tested them? Did they work at all after the crash?


Are these the cheap $7.00 servos? Were they new or used servos? How old were they? How long had you been flying that day?

When you need help with something, you need to state, How, What, When and Where.

Frank


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Old 12-09-2012, 05:24 PM
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Default RE: Aircraft Servos

What voltage rx battery are you useing 4.8 volt or 6.0 volt. With a DX 7 radio which I am useing 6.0 volt NiMi is the safer option to use .
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Old 12-10-2012, 07:55 AM
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Default RE: Aircraft Servos

More than likely what you observed after the crash is a result from the crash. You may have stripped gears in the servo or any number of other results from the crash. I havent read the testing procedures that AT linked to but that is what you will need to do. Remove the gear and set it up on the bench, hook it up like it would be in the plane and test it. Test the battery under load. This will be a process everybody should go through after a crash. Sorry it happened but at least you might learn something from it.
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