X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-we0-f182.google.com ([74.125.82.182] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6983632 for flyrotary@lancaironline.net; Thu, 17 Jul 2014 16:25:26 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.82.182; envelope-from=ceengland7@gmail.com Received: by mail-we0-f182.google.com with SMTP id k48so2432651wev.27 for ; Thu, 17 Jul 2014 13:24:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=sEY2DaQWIyEVs5otwBtyQ/Nj9L6ECZ7sxdtK+3VTZec=; b=XuZNuHippQ+DJ43J9fFRK2H2HNvXx61Nuxy0gHSPoFmyETBSx3zFdaCm9oup9LutWu 1g0r5FJGCOWkZMdMWw16NMCvkuX3Tvg5gIq6Gyi8MYDRZpSWrrLM4IDNKjala8O3cNxB FiO22n23INXEKgpcv14GvSqZXB6un5yrIuRcwnqHGRvBFFcfN1xI0+0ifuiRJQbriVQk q0oYIJEbROnjeq6bVmtRAF2HYvPs/NbBSVhiHPi+IXAqE4wUI9HGcR/zRjcgw96dis6V vgPF0RMvjXKExlvNQ2hhQqhNhMlVdyKMc+01LRp0+uid8VCpBX7jJUYQoJCXfpvWbvcv TaXw== MIME-Version: 1.0 X-Received: by 10.180.74.11 with SMTP id p11mr25104937wiv.68.1405628689538; Thu, 17 Jul 2014 13:24:49 -0700 (PDT) Received: by 10.216.176.199 with HTTP; Thu, 17 Jul 2014 13:24:49 -0700 (PDT) In-Reply-To: References: Date: Thu, 17 Jul 2014 15:24:49 -0500 Message-ID: Subject: Re: [FlyRotary] Re: power circuit design, was: actual current use by a rotary? To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=f46d043891c3b9e3a504fe696e14 --f46d043891c3b9e3a504fe696e14 Content-Type: text/plain; charset=UTF-8 Thanks, Steve. Guess I should have known even more options would turn up. :-) I like the idea, but how did you protect the wires going *to* the switch-breakers? Are they just on a high current bus with the rest of your breakers? If so, it might not work for me, since I'm using automotive fuse panels. Right now, I've planned for multi-pole injector switches wired as shown in the manual (but with a separate pole for each injector), mounted next to Tracy's engine control panel (the coil test switch is there, too). Charlie On Thu, Jul 17, 2014 at 2:08 PM, Steven W. Boese < flyrotary@lancaironline.net> wrote: > ------------------------------ > *From:* Rotary motors in aircraft on behalf > of Charlie England > *Sent:* Thursday, July 17, 2014 12:14 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] power circuit design, was: actual current use by a > rotary? > Charlie, > > I chose to install switch type circuit breakers, one for the primary > injectors and one for the secondary injectors. I did this because if one > injector fails, the backup function requires the corresponding injector of > the other rotor to be shut off and then the cold function to be activated. > If there were a power draw that tripped the breaker, the result would > already take care of that first step. The down side is that the > cold switch needs to be used for the backup function instead of being taken > care of by the second pole of the recommended DPDT injector switch. This > required no additional space on the panel. > > I did the same thing for the leading and trailing coils but for testing > purposes rather than risk mitigation. > > Steve Boese > RV6A, 1986 13B NA, RD1A, EC2 > > > > Well, time for some followup. > > My 1st draft for circuit protection looked a lot like what Steve describes > (thanks, Steve), with individual fuses for virtually everything, including > an individual fuse for each injector and each ignition coil. After > ruminating over the actual loads for the injectors & coils, I'm having > second thoughts. The GM coil harness I have in hand has a single DC power > wire for all four coils that it feeds (obviously isn't a part intended for > flight, but included in Tracy's installation manual). > > The obvious concern is whether an individual coil or injector failure has > a statistically significant risk of taking out the power supply that's > fused for the total load. If there's no statistically significant danger, > weight & complexity could be reduced by feeding the coils and injectors as > groups. > > So, is there any consensus on how to handle injector & coil wiring? IIRC, > there have been some coil failures in flight; were those planes wired with > a single fuse/breaker protecting all the coils, or with individual > fuses/breakers for each coil? What about the injectors? > > Any failure modes I'm missing? (other than a dead short on a supply wire, > of course) > > Thanks, > > Charlie > > > > > --f46d043891c3b9e3a504fe696e14 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Thanks, Steve.

Guess I should hav= e known even more options would turn up. :-)

I like the = idea, but how did you protect the wires going *to* the switch-breakers? Are= they just on a high current bus with the rest of your breakers? If so, it = might not work for me, since I'm using automotive fuse panels. Right no= w, I've planned for multi-pole injector switches wired as shown in the = manual (but with a separate pole for each injector), mounted next to Tracy&= #39;s engine control panel (the coil test switch is there, too).

Charlie


<= div class=3D"gmail_quote">On Thu, Jul 17, 2014 at 2:08 PM, Steven W. Boese = <flyrotary@lancaironline.net> wrote:

From: Rotary motors in aircraft <flyrotary@lancaironlin= e.net> on behalf of Charlie England <flyrotary@lancaironline.net> Sent: Thursday, July 17, 2014 12:14 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] power circuit design, was: actual current use b= y a rotary?
=C2=A0Charlie,
=C2=A0
I chose to install switch type circuit breakers, one for the primary i= njectors and one for the secondary injectors.=C2=A0 I did this=C2=A0because= =C2=A0if one injector fails, the backup function requires the corresponding= injector of the other rotor=C2=A0to be shut off and then the=C2=A0cold function to be activated.=C2=A0 If there were a power d= raw that tripped the breaker, the result would already take care of that fi= rst step.=C2=A0 The down side is that the cold=C2=A0switch needs to be used= for the backup function instead of being taken care of by the second pole of the recommended DPDT injector switch.=C2=A0 This = required no additional space on the panel.
=C2=A0
I did the same thing for the leading and trailing coils but for testin= g purposes rather than risk mitigation.

Steve Boese
RV6A, 1986 13B NA, RD1A, EC2
=C2=A0
=C2=A0
=C2=A0
Well, time for some followup.

My 1st draft for circuit protection looked a lot like what Steve describes = (thanks, Steve), with individual fuses for virtually everything, including = an individual fuse for each injector and each ignition coil. After ruminati= ng over the actual loads for the injectors & coils, I'm having second thoughts. The GM coil harness= I have in hand has a single DC power wire for all four coils that it feeds= (obviously isn't a part intended for flight, but included in Tracy'= ;s installation manual).

The obvious concern is whether an individual coil or injector failure has a= statistically significant risk of taking out the power supply that's f= used for the total load. If there's no statistically significant danger= , weight & complexity could be reduced by feeding the coils and injectors as groups.

So, is there any consensus on how to handle injector & coil wiring? IIR= C, there have been some coil failures in flight; were those planes wired wi= th a single fuse/breaker protecting all the coils, or with individual fuses= /breakers for each coil? What about the injectors?

Any failure modes I'm missing? (other than a dead short on a supply wir= e, of course)

Thanks,

Charlie





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