[NSRCA-discussion] Two killed by model airplane

Sun May 21 10:52:44 AKDT 2006

Bob:
Ther are kill switches that can be set to work with a pre-set failsafe output.  I think the problem with what you wuold like to see is that without some failsafe response from the receiver, it's hard to predict what you will get during interference. I don't think it's unsolvable though.  If you used a spare channel for the kill switch, even a PPM receiver solution could work.  A partially reliable solution would require either a PCM or PPM receiver to reliably hold one position and anything outside a narrow tolerance range would trigger the cutoff.  That's easy to do.  

Here's a better solution, but it requires some cooperation from the radio manufacturers.  What is really needed is a so-called "keep-alive" signal sequence from the transmitter.  Veryone should standardize on the same, exact thing in a case like this.  Keep-alives are used all the time in computing gear, to help "harden" the solution for failure detection/recovery etc.  It's as old as dirt, used in Telecom, other mission critical stuff for medical, military etc.  The idea in its simplest form is that a cyclic signal with known attributes is sent to the "target" (the kill switch for us).  If the target doesn't get what it expects within it's timeout interval, it can initiate whatever action is deemed necessary.  

This can be far superior than just camping on a simple steady pulse position value, since you can make the probability of continuously receiving a "good" sequence from a bad RF link astronomically high.  In other words, you can set the level of signal link deterioration before acting on it to something very fleeting or make it take longer to detect if you want a higher certainty that it is time to act on a bad link.  So you could make the "stay running" sequence a known series of varying pulse widths, even using varying timing between the varying widths.  None of this is especially difficult to do, nor should it be very expensive.  On top of this, you could een couple the engine kill response to a loud piezo speaker and chirp out a warning - "Incoming".  Make it an industry standard chirp sequence and it wuold be an unmistakable sign that a model was no longer under control of a good link.  Then, any 3rd party devices that want to work with this have to get on board and be redesigned to recognize the standard LOS (loss of signal) protocol. 

Ed

  ----- Original Message ----- 
  From: Bob Pastorello 
  To: NSRCA Mailing List 
  Sent: Sunday, May 21, 2006 1:48 PM
  Subject: Re: [NSRCA-discussion] Two killed by model airplane

  I have oft wondered if an "ignition CUT off" that sensed loss of RX decoder outputs that would KILL the motor wouldn't help.  It would at least mitigate the energy of the impact.  Never heard of one out there that works exactly like I'm describing, and it would probably only be effective for gassers at this stage, but it may REDUCE the degree of injury.

  I fear full DUAL RF_Link redundancy in our future....

  Bob Pastorello
  www.rcaerobats.net
  rcaerobob at cox.net
    ----- Original Message ----- 
    From: brett terry 
    To: NSRCA Mailing List 
    Sent: Sunday, May 21, 2006 12:39 PM
    Subject: Re: [NSRCA-discussion] Two killed by model airplane

    Lest we forget, or become careless because of the relative size of our planes to the 50% scale Pitts that killed the people in Hungary, remember a young girl was killed in China a few weeks ago by a .21-size trainer.  

    Like you said, it is only a matter of time.  We must always be wary of the danger, and make sure everybody at our fields also follow safe practices.

    On 5/21/06, Ed Miller <edbon85 at charter.net> wrote: 
      Having just spent a week at the Joe Nall event it is clear to me it is only a matter of time before a similar tragedy happens here in the US. 
      Ed M.
      ----- Original Message ----- 
      From: mike mueller 
      To: NSRCA Mailing List 
      Sent: Sunday, May 14, 2006 11:10 PM 
      Subject: Re: [NSRCA-discussion] Two killed by model airplane

       Sad news,it should remind us that were only a serious accident away from potentially being grounded. We can all say that we fly safe and yada yada yada but if the radio fails it could be a disaster. Man I hope this doesn't happen again. I once witnessed a young girl getting hit by a plane in the 70's and it still haunts me.
      --Mike
      Doug Cronkhite <seefo at san.rr.com> wrote: 
        Yep.. 4 others were injured. Looks like it was a 3W Pitts Model 12 that crashed. The pilot was arrested by police at the scene..

        -Doug

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        From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ed White
        Sent: Sunday, May 14, 2006 7:50 PM
        To: NSRCA Mailing List
        Subject: [NSRCA-discussion] Two killed by model airplane

        Yikes.

        http://english.mti.hu/default.asp?menu=1&theme=2&cat=25&newsid=219887

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