Mailing List flyrotary@lancaironline.net Message #36129
From: Joe Ewen <jewen@comporium.net>
Subject: Re: [FlyRotary] Re: A solution? was : The truth??? / Injector flow rate mystery solved
Date: Mon, 12 Mar 2007 17:12:46 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
My original thoughts regarding a dropping resistor were the result of being bored while lying in bed with a 102 degree fever, otherwise I would have likely been working on my airplane.  In the end, I believe Tracy is likely the best person to devise the ultimate solution.  But in fairness to Tracy, he seems to be a rather busy person juggling his manufacturing, airplane building, technical support, and product development may not leave much time to work on this particular issue.  So I threw my 2 cents into the ring.  My first though was an RC circuit, but thought it may not be a reasonable solution due to its Time/Decay rates.
 
Last point I would like to make is anyone considering using a MOV "Please read the following info:" 
 
Like any solid state device an MOV is subject to degradation (quickly if the power through it is greater than its heat dissipation capacity).  Further, unlike many other solid state devices that fail in the off state when they loose their internal smoke -  a MOV can fail in the ON state.
 
Sincerely,
Joe (Hoping I have not offended anyone, or be banned from FlyRotary like so many others have been from the other list.)
 
----- Original Message -----
Sent: Sunday, March 11, 2007 2:30 PM
Subject: [FlyRotary] Re: A solution? was : The truth??? / Injector flow rate mystery solved

What about MOV's?  Typical transient response time measured in nanoseconds...

   <Marv>  




"Steven Boese" <sboese@uwyo.edu> wrote:

Ed and Joe,

The diode in the EC2 allows the current from the collapse of the
injector magnetic field to flow to the positive supply rail (~14V); it
doesn't oppose this. A resistor allowing this current to flow would
also result in a close delay since the current flowing is what maintains
the magnetic field during this delay. What is needed is a way to
decrease the rate of voltage rise just after the EC2 pulse ends so
arcing in the A/B selection relay is suppressed. After the relay
contacts open enough that an arc is no longer possible (which shouldn't
take long) an open circuit condition now would allow the injector to
close quickly. The arcing may or may not be a problem any given tim Ed
 

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