[NSRCA-discussion] Arming Switch

Sun Feb 12 14:31:03 AKST 2012

Good discussion with valid points for and against.  Personally, I am in favor of an arming plug for 2 reasons.  

First and this is a persnaol convenience item for me as a pilot and as a helper/caller.  I like to connect the batteries, put the canopy on and be ready to go, all I have to do is a radio check and then insert the arming plug.  Like I said, this is more of a personal convenience for me.  And I am not trying to impose my convenience on anyone else.

Second, and much more important me is the disarming of the batteries after a flight.  When a competitor lands and his helper goes out to the plane, the pilot is coming down for the excitement/tension of the flight, probably talking with judges, etc, basically distracted.  The helper retrieves his plane and the first thing that happens is the helper removes the plug and gets off the runway, may or may not turn the RX off.  No training, doesn't have to know how to remove the canopy, etc.  Your favorite caller/helper may not be available because they are judging, helping someone else, or just irritated with you because you screwed up calling their last flight....  ;-)  Anyway, if there is no arming plug, the helper may or may not know how to remove the canopy or, they just carry it back to you or your pit area.  This is the part that really bothers me. The pilot will probably come back and remove the batteries if he knows you did not.    Or,,,,,,  the pilot is still talking with someone....  yes, the pilot may have switched off his transmitter, the helper may have turned the receiver off and the ESC should be in failsafe mode.   If I am the helper and there is no arming plug I make it a point of telling the pilot the plane is still 'hot'.

I seldom see issues at the beginning of a flight, at the contests or at the practice field.  However, I have seen numerous issues after flights and like I said, this is the part that concerns me.  The plane is in the middle of a pit area, not on the flight line typically facing away from everyone.

Just my opinion but the reasons I prefer an external arming plug.  

A totally different reason I like arming plugs is the spark errosion occuring during initial contact as the capacitors charge.  On the Deans connectors, it is the negative contact that erodes and after hundreds of flights it is very obvious there is a lot of contact area gone.  All I do is make a new arming plug.  If I don't have an arming plug, it is the battery contact(s) that are being eroded.  With the extended life of our batteries, this can become an issue over time.  Minor point, I know but I would rather replace an arming plug than tear the male Deans plug out of my plane for replacement.

Don

-----Original Message-----
From: Dave Harmon <k6xyz at sbcglobal.net>
To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org>
Sent: Sun, Feb 12, 2012 3:01 pm
Subject: Re: [NSRCA-discussion] Arming Switch

Hi Keith….
Actually I DID take into account that there IS a possibility that the ESC could fail….but I feel the odds of that happening are as I said, a lot less than someone mishandling a transmitter.
How about just plugging the battery in and putting the canopy on within the 3 minute starting period??
The airplane should not have to just sit there plugged in and ready to go like a fueled up glow powered airplane….
After landing someone picks up the model and turns off the radio switch….if the helper picks up the airplane and the ESC malfunctions he has ahold of it.
I understand your and others concerns but I just don’t think the external plug thing is necessary.  
I just don’t see the need to have a battery in the plane unless it is manually restrained and going to be flown within the next 3 minutes.
I don’t mean to imply that I plug in the battery without straddling the fuselage….I do!

Dave Harmon
NSRCA 586
K6XYZ[at]sbcglobal[dot]net
Sperry, Ok.

From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Keith Black
Sent: Sunday, February 12, 2012 4:29 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Arming Switch

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. 

Regarding pulling the disconnect (whether under canopy or via external arming pin), step over the model between wings and stab (just like we used to run up the glow models) and reach down to pull the plug. If it goes full throttle the back of your legs will stop forward momentum.

I see far too often that people switch off their radios with the plane in a potential dangerous position. This is putting a lot of trust in the technology when it's not necessary. When I retrieve my model,  transmitter in hand or not, I make sure it is pointed away from people or property.

Keith 

On Sun, Feb 12, 2012 at 2:28 PM, Dave Harmon <k6xyz at sbcglobal.net> wrote:

+1 on that.
Rather than having a disconnect, I think ensuring that the fail safe function of the radio is set properly is the way to go.
Generally…with today’s 2.4g radios…..not 72mhz PCM radios….I trust the electronics more than someone holding the transmitter. 
Besides….with a disconnect it would be my luck to rip the side of the fuselage off and start a fire that way………or not being able to let go of a full throttle model to pull the disconnect….in this case just turn off the transmitter and/or have an external radio switch and turn off the receiver.
The ESC will shut off the motor when the ESC loses the pulse from the receiver…even if the failsafe is NOT configured correctly.
Everyone already knows this….or should know it…. but it’s a good thing to mention anyway…..

Dave Harmon
NSRCA 586
K6XYZ[at]sbcglobal[dot]net
Sperry, Ok.

From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Keith Hoard
Sent: Sunday, February 12, 2012 1:44 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Arming Switch

I'd rather not cut a hole in my plane in the first place, or add another point of failure to the system. . . .

Keith Hoard
Collierville, TN
khoard at gmail.com

On Sun, Feb 12, 2012 at 1:37 PM, Ronald Van Putte <vanputte at cox.net> wrote:

You can mount a female Deans connector in a piece of thin plywood, use Pacer Pro Zap to glue the Deans connector to the plywood and, after cutting an appropriate hole in the side of the fuselage, glue the assembly inside the fuselage.  Use a male Deans connector with the leads soldered together as an arming plug.

Or you can buy a SharpRC SafeArm (http://www.sharprc.com/catalog/index.php?cPath=43)

Being cheap, I do the former.

Ron Van Putte

On Feb 12, 2012, at 11:55 AM, Ron Hansen wrote:

What are the available arming switch options?

Thanks

Ron

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