X-Virus-Scanned: clean according to Sophos on Logan.com From: "steve Izett" Received: from mail-pd0-f171.google.com ([209.85.192.171] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6984064 for flyrotary@lancaironline.net; Thu, 17 Jul 2014 20:56:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.192.171; envelope-from=steveize@gmail.com Received: by mail-pd0-f171.google.com with SMTP id z10so4032084pdj.16 for ; Thu, 17 Jul 2014 17:55:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:content-type:message-id:mime-version:subject:date:references :to:in-reply-to; bh=EdcOYMg1w87qptaYFvwN2y8JTxtRXGyLxbBQ5EBz3hY=; b=KrPN3nAyqvdritHYFGoCHRl90zS2DwFClz2aLafP98IvP18gWHX+1Eo2CP6ZivvS9K VQm4SCWTiUvhNiFrCjaBjuDqFtZLk5F7KycFo/w1dAq6HY+qUqNQH40GtMLCsN5UX1vj S2Z2lVq0LwHAiPTOJcaGx5R+EIFBsiv178fvfgCFFccBsRQTIT0UUUenMKjEbl2Jc95T UOT7Ksv++Vg0P5F7s6iX7qXCAPZ1rgIMDh5eQ2gwEZNz6tTgAjzHYeoVACeUOefFqBhZ 4GlIJ0QL+obZOAujgCrBTAHM7qj3SwDH5JAE3HT7CDQjtYhRtiUchgAt3BsOAA+2KU/0 k1qQ== X-Received: by 10.70.87.206 with SMTP id ba14mr1049059pdb.4.1405644949611; Thu, 17 Jul 2014 17:55:49 -0700 (PDT) Return-Path: Received: from [10.1.1.12] (58-7-175-226.dyn.iinet.net.au. [58.7.175.226]) by mx.google.com with ESMTPSA id kh7sm16235134pad.8.2014.07.17.17.55.47 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 17 Jul 2014 17:55:49 -0700 (PDT) Content-Type: multipart/alternative; boundary="Apple-Mail=_0A2A87AA-2273-4CC6-8540-3BA513E6A550" Message-Id: Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.2\)) Subject: Re: [FlyRotary] Re: power circuit design, was: actual current use by a rotary? Date: Fri, 18 Jul 2014 08:55:44 +0800 References: To: Rotary motors in aircraft In-Reply-To: X-Mailer: Apple Mail (2.1878.2) --Apple-Mail=_0A2A87AA-2273-4CC6-8540-3BA513E6A550 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 Charlie I forgot to mention what others had raised. As I mentioned re: deleting the individual Pri Sec Injector switches. If = I do this (delete them) then the separate feeds to Pri and Sec injectors = would seem overkill in my mind as I thought the chances of an injector = going short circuit was very low. On the coil side I would prefer to keep Leading and Trailing feeds = independant as I don=92t have the same faith in the coils not failing = short circuit. Steve =20 On 18 Jul 2014, at 4:24 am, Charlie England = wrote: > Thanks, Steve. >=20 > Guess I should have known even more options would turn up. :-) >=20 > 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). >=20 > Charlie >=20 >=20 > On Thu, Jul 17, 2014 at 2:08 PM, Steven W. Boese = wrote: >=20 >=20 > 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, > =20 > 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. > =20 > I did the same thing for the leading and trailing coils but for = testing purposes rather than risk mitigation. >=20 > Steve Boese > RV6A, 1986 13B NA, RD1A, EC2 > =20 > =20 > =20 > Well, time for some followup. >=20 > 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). >=20 > 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. >=20 > 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? >=20 > Any failure modes I'm missing? (other than a dead short on a supply = wire, of course) >=20 > Thanks, >=20 > Charlie >=20 >=20 >=20 >=20 >=20 --Apple-Mail=_0A2A87AA-2273-4CC6-8540-3BA513E6A550 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 Charlie

I forgot to mention what = others had raised.
As I mentioned re: deleting the individual = Pri Sec Injector switches. If I do this (delete them) then the separate = feeds to Pri and Sec injectors would seem overkill in my mind as I = thought the chances of an injector going short circuit was very = low.
On the coil side I would prefer to keep Leading and = Trailing feeds independant as I don=92t have the same faith in the coils = not failing short = circuit.

Steve

 
On 18 Jul 2014, at 4:24 am, Charlie England <flyrotary@lancaironline.net> wrote:

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 <flyrotary@lancaironline.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 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






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