X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from an-out-0708.google.com ([209.85.132.250] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2556068 for flyrotary@lancaironline.net; Tue, 04 Dec 2007 16:09:15 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.132.250; envelope-from=msteitle@gmail.com Received: by an-out-0708.google.com with SMTP id b2so920140ana for ; Tue, 04 Dec 2007 13:08:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=TiQqluU6H/IKN5w+d2+JLGQoF1aMNw6ej6vt8oYhtEI=; b=w1+fprLdt/lBiqKBBOjLUWqP8MT8ahQHB7ve8G08ZoYTWXRtOJLLMGhiLfSfZS+eWQYUFleDQw+J5CVX3GeM4+FrqtISYw8SR6GAfrpgwSADjEKZ7M3++nDpJWgkVjtODy68/JL5jX1dNCTw1XcZ1WFLeBAgpT4lrSMn9zroFYk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=JVj6G9WMHScYSveEkPo6YHrp8hmJD3oYYfjwESrzeNP1k4zQZMT59SNiEGHE9dBDIlGsdJ4ywPBXFgoZ3P8TQFcNQhgxuCbWbPx9SnM/FjHv5qA0VQJWLmk9WuvfJ1BsMZr7FVBnxEwJK/QqUTGru2yjt144pRmUvCY8FMJwpdM= Received: by 10.150.158.8 with SMTP id g8mr367884ybe.1196802515553; Tue, 04 Dec 2007 13:08:35 -0800 (PST) Received: by 10.150.157.18 with HTTP; Tue, 4 Dec 2007 13:08:35 -0800 (PST) Message-ID: <5cf132c0712041308q5a7bafacn16821cd0fac8a6e1@mail.gmail.com> Date: Tue, 4 Dec 2007 15:08:35 -0600 From: "Mark Steitle" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: circuit breakers In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_3459_298779.1196802515552" References: ------=_Part_3459_298779.1196802515552 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline So, what's the most reliable method of getting the big fat wire from the battery (in the tail) to the essential bus at the panel? I had initially connected this wire directly to the battery (unfused), but later added the big 60 amp fuse. Being a fiberglass plane, would a carefully run unfused wire be preferrable to a fused wire? Is a relay more reliable than a big fuse? Would a solid-state relay be even better? Mark S. On 12/4/07, Al Gietzen wrote: > > > > That's what I did... Flight Critical bus is always hot, although I did ad= d > a 60 amp fuse back near the battery. > Mark S. > > Is that fuse in the only power path to the engine critical bus? I think > fuses are a very reliable way to go; but for this application they are > synonymous with "fault tolerance". IOW, blowing one fuse does not shut y= ou > down. Actually, I would also apply the fault tolerance idea to the use o= f > breakers for critical items. > > One of the nice things about our setup is we have dual plugs, dual > injectors, dual controllers, and dual fuel pump. That gives you the > potential for very high reliability - a failure of any one of the pair do= es > not put you on the ground. I chose to use a separate circuit to each to > gain failure tolerance. Each circuit is protected with a fuse, and the fu= se > holder is powered directly from both batteries with isolation diodes so e= ven > a battery failure doesn't stop the engine. > > Wires are cheap and light and very reliable. Fuses cost only pennies, so > change them out and check the contacts every annual, or every 6 months if > you feel like it. I like that better than a breaker that has been in the > panel for 10 years. Fault tolerance =3D high reliability. (I almost said = =96 > fuses and fault tolerance, but I don't want to start that fuses vs breake= rs > discussion againJ) > > FWIW, > > Al > > > ------=_Part_3459_298779.1196802515552 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
So, what's the most reliable method of getting the big fat wire fr= om the battery (in the tail) to the essential bus at the panel?  I had= initially connected this wire directly to the battery (unfused), but later= added the big 60 amp fuse.  Being a fiberglass plane, would a careful= ly run unfused wire be preferrable to a fused wire?  Is a relay more r= eliable than a big fuse?  Would a solid-state relay be even better?&nb= sp;=20
 
Mark S.

 
On 12/4/07, = Al Gietzen <ALVentures@cox.net= > wrote:

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">That's what I did... Flight Critical bus= is always hot, although I did add a 60 amp fuse back near the battery.&nbs= p;
 Mark S.

Is that fuse in the only power = path to the engine critical bus?  I think fuses are a very reliable wa= y to go; but for this application they are synonymous with "fault tolerance= ".  IOW, blowing one fuse does not shut you down.  Actually, I wo= uld also apply the fault tolerance idea to the use of breakers for critical= items.=20

One of the nice things about ou= r setup is we have dual plugs, dual injectors, dual controllers, and dual f= uel pump. That gives you the potential for very high reliability - a failur= e of any one of the pair does not put you on the ground.  I chose to u= se a separate circuit to each to gain failure tolerance. Each circuit is pr= otected with a fuse, and the fuse holder is powered directly from both batt= eries with isolation diodes so even a battery failure doesn't stop the engi= ne.=20

Wires are cheap and light and v= ery reliable. Fuses cost only pennies, so change them out and check the con= tacts every annual, or every 6 months if you feel like it. I like that bett= er than a breaker that has been in the panel for 10 years. Fault tolerance = =3D high reliability. (I almost said =96 fuses and fault tolerance, but I d= on't want to start that fuses vs breakers discussion again J<= font face=3D"Verdana" color=3D"blue" size=3D"2"> )

FWIW,

Al

 = ;


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