[NSRCA-discussion] Arming Switch

[Bob Richards]

Ok, not so much of a failure of the ESC, but in failsafe setup, operator error, etc. I have witnessed that.
 
How many times has anyone seen where the motor started running when the receiver was powered off? 
 
For the arming plug to provide safety, everyone associated with the operation must be aware (pilot, caller, anyone picking up the plane). There is still more of a chance that this will fail at the end of the flight than before, but that is the case whether there is an arming plug or not. 
 
Bob R.


--- On Mon, 2/13/12, Peter Vogel <vogel.peter at gmail.com> wrote:


From: Peter Vogel <vogel.peter at gmail.com>
Subject: Re: [NSRCA-discussion] Arming Switch
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Cc: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Monday, February 13, 2012, 10:30 AM




>From the accidents I've seen or heard of, the issue is not a failure before takeoff, but rather a failure after landing (ESC already armed) or a pilot mishap that results in an unintentional bump of the throttle lever (neck strap, coat, etc)


Peter+

Sent from my iPhone4S

On Feb 13, 2012, at 7:18 AM, Bob Richards <bob at toprudder.com> wrote:









Keith,
 
My gut instinct is to agree with you on this, but I have to wonder what is the possibility that there would be a failure mode where the controller could go full throttle without an input from the receiver. For the brushless controllers, the micro in the controller must be working properly for the motor to run - period - since it has to sense the feedback from the motor and operate the outputs in proper phase for the motor to run at all (this would be a different discussion if we were talking about *brushed* controllers). The more likely failure would be that it applies power to one or more motor wires - not pulsed - that would do little more than heat up the motor and burn a winding, but not turn the motor over.
 
Is it possible for the micro think there is a full-throttle input when there isn't? Most controllers that I know of will not arm if it powers up with anything other than a low-throttle signal from the receiver. It has to sense a low-throttle signal that then transitions to something else before it starts the motor turning. Is this a possible failure mode for an ESC - I don't know since I don't know any specifics of the circuitry or firmware programming of ESCs, but I seriously doubt this can happen and if it can, the likelyhood would be extremely low.
 
Of course, not having the battery connected to anything is safe. Safer yet is to just stay at home, but we have to decide what is an acceptable risk.
 
Bob R.
 
 


--- On Sun, 2/12/12, Keith Black <tkeithblack at gmail.com> wrote:




Dave, you're points are correct, but you're not taking into account a malfunction of the speed controller itself. They have been know to malfunction, so the safest approach, as Earl suggests, is to assume that anytime the battery is connected to the controller the motor may go to full throttle. Until you unplug the battery the thing is hot and dangerous regardless of your fail safe or switches on the transmitter.  



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