[NSRCA-discussion] Failsafes for Electric?

Fred Huber fhhuber at clearwire.com
Tue Aug 8 20:37:41 AKDT 2006 

Almost all ESC's are designed to kill the motor on loss of coherant signal.  The danger is in if the RX sends out something that the ESC THINKS is a good signal, but is not what the TX is set for.  (Mis-setting PCM failsafe can give the same result...  The failsafes are only good if you actually pay attention to how you set them)

If you are paranoid about it... there are failsafe circuits for sale you can get to put between a PPM RX and the servo or ESC.  

I must be a bit paranoid... I've taken to putting these things in on my throttle servos for planes with larger than .60 size glow engines.  The ones I am using have settable falisafe position (put the channe to the desired failsafe position and hold a button for about 30 sec.. its set) and they will trigger the failsafe on low RX battery.  The low RX batt function has saved one model on 2 occasions.... found a bad RX batt and just flew too much the other time. (Too much fun is my enemy... breaks a lot of planes)

If you are going to require throttle failsafes for Pattern... you need to require them for all models... glow, gas, electric... any can have a throttle excursion. (usually caused by bumping the stick or something.... where a failsafe won't help)

The little voltwatch devices would be the first thing I would make required... not failsafes.  I've seen too many planes go in from dead RX batteries.  A little red LED saying its not safe to fly works.  I put one of these in the club's trainer (and I have them in most of my planes now)  One glance and you KNOW if you have RX power.  They come in 4 cell and 5 cell versions,,, and a version that is switch selectable for 4 cell or 5 cell.

*********  

The way I have my large plane set up... I'm using 4 mm gold bullet connectors on the LiPos. ("polarized" for prevention of reverse connections) The + lead bullet is outside the cowl.  I can unplug the batt (or visually check if its plugged) with just a glance.  When I find a fuse holder I like... I'll have the fuse visible (hopefully a red one that will show up really well against the white cowl)  I make sure any electric model I fly can have the batt disconnected from the ESC without taking anything apart to get at the connection.

BTW.. when heat-shrink-tube covering a male bullet.'s solder joint.. let excess hang out over the whole bullet.  Don;t shrink the part that covers the actual plug.  You have a shield to prevent shorting the male connector against anything. :)  Sorry... I don't take decent digital pics of small stuff.... but everyone that has seen my plugs on this plane thinks its a great idea.  costs just an extra 1/2 inch of heat shrink tube per male bullet. (the part you've probably been triming after heat shrinking...)
  ----- Original Message ----- 
  From: Keith Black 
  To: NSRCA Mailing List 
  Sent: Tuesday, August 08, 2006 10:42 PM
  Subject: Re: [NSRCA-discussion] Noxville Contest??


  I use an arming pin and always instruct my callers to pull the pin as the first thing they do when they pick up the plane for me.

  Another VERY important item is that it should be required that anyone flying electric MUST us a PCM RX and failsafe must be set for throttle going to zero.  If a PPM RX is used and the antenna is lowered, or power turned off before the plane is turned off this could result in a run-away electric.

  Keith Black

  ----- Original Message ----- 
    From: John Ferrell 
    To: NSRCA Mailing List 
    Sent: Tuesday, August 08, 2006 3:42 PM
    Subject: Re: [NSRCA-discussion] Noxville Contest??


    I personally witnessed an instance of electric starting unexpectedly at the Nats. Since I was only around Masters & FAI I believe it safe to dismiss the problem as lack of experience.

    I feel it essential to implement some kind of safety device to prevent this from occurring. I would prefer a mechanical lockout of some sort or at least an arming plug.

    The airplane was being carried back to the pits when the failure occurred. The handler was on top of the problem but it could have happened after the plane was parked.

    It is a disaster waiting to happen.

    John Ferrell    W8CCW
    "My Competition is not my enemy"
    http://DixieNC.US

      ----- Original Message ----- 
      From: J.Oddino 
      To: NSRCA Mailing List 
      Sent: Tuesday, August 08, 2006 12:53 PM
      Subject: Re: [NSRCA-discussion] Noxville Contest??


      Another reason to go electric.

      Jim O
        ----- Original Message ----- 
        From: John Ferrell 
        To: NSRCA Mailing List 
        Sent: Sunday, August 06, 2006 9:38 AM
        Subject: Re: [NSRCA-discussion] Noxville Contest??


        I have an $8000 left thumb. They installed a couple of options while they were rebuilding. It warns of weather changes and also serves as an alarm clock (sometimes).

        I recommended that a student headed for a pro basket ball career give up RC until the career was behind him.

        John Ferrell    W8CCW
        "My Competition is not my enemy"
        http://DixieNC.US

          ----- Original Message ----- 
          From: BUDDYonRC at aol.com 
          To: nsrca-discussion at lists.nsrca.org 
          Sent: Sunday, August 06, 2006 11:10 AM
          Subject: Re: [NSRCA-discussion] Noxville Contest??


          About two years ago I got my finger in one It cut the right index finger off at the first joint. Wrapped the finger in a towel went to the hospital with the severed finger, three month's and $6000.00 later it was almost as good as new except it is still numb on the end. APC's show no mercy.
          Buddy 


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