[NSRCA-discussion] Arming Switch

[Dave Lockhart]

When I initially started flying electrics, I used to leave them running at a
low idle anytime they were plugged in..pretty obvious indicator of the
condition of armed / not armed.  I stopped doing this because I felt the
likelihood of a problem was greater from bumping the throttle stick when at
idle in comparison to bumping the throttle stick with a kill switch engaged.

 

Regards,

 

Dave

 

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of J N Hiller
Sent: Monday, February 13, 2012 12:14 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Arming Switch

 

I don't fly electric in competition (yet) but I setup the TX the same as my
glow airplanes using the throttle cut function, which disables the stick on
my SD-10G, preventing accidentally bumping it and energizing the motor.
Since I'm BESC the airplane is restrained when plugging in the battery and I
still turn on the TX first, mostly out of habit. 

 

After landing there are usually bystanders gathering around asking questions
and I explain that I need to unplug the battery to be safe before engaging
in Q&A. I guess I just don't trust it any more than a still running motor.

 

In a competition airplane I would use an arming plug as some of you already
do.

Jim

 

 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Peter Vogel
Sent: Monday, February 13, 2012 7:31 AM
To: General pattern discussion
Cc: General pattern discussion
Subject: Re: [NSRCA-discussion] Arming Switch

 

>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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