X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.24] verified) by logan.com (CommuniGate Pro SMTP 5.3c2) with ESMTP id 3987791 for flyrotary@lancaironline.net; Tue, 24 Nov 2009 09:43:35 -0500 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.24; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 9so1340319qwb.25 for ; Tue, 24 Nov 2009 06:43:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=8fYRirnaJquMJsoDew3EoisNus0j+LuX14NnUORikeg=; b=X2DJBla6G+oxI1QlYFau7IddtYLq1YDWxIJFJjrIDho4V2V/Un7/kxb41bR8dZMqlK mFxiU8KpF2TvoXQVcNlKKEzYLXRpsXtX83CRdUGoKAPQixTADbJMj5CQBGlCvuwWlOZF QtI/U+i+0X/vnVneqsj/yoHkOUBJH1jEsAZm4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=RcgCNp1PgvgqzOCKXFjgbrybQKTtRnylLfiKA3QHKVOjROh0BVIZUNjvfUBttyAZmU 4qKY03bb4ItpGQ41rC1y0/54EMZc4rG4lUE23XXnfMeuIg3ZtK0doSQSs9a2j3aLRF7n 76XYQuXIvPA13H6qdXCUnoJQsgKD6dQ81o9BM= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.123.154 with SMTP id p26mr3224591qar.218.1259073776942; Tue, 24 Nov 2009 06:42:56 -0800 (PST) In-Reply-To: References: Date: Tue, 24 Nov 2009 09:42:56 -0500 X-Google-Sender-Auth: 7f3df28925007ea7 Message-ID: <1b4b137c0911240642rfe29732q955061af43f0a736@mail.gmail.com> Subject: Re: [FlyRotary] Re: No start From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=00c09f923194387f7b04791ef5a8 --00c09f923194387f7b04791ef5a8 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I doubt anodizing is a factor. Keep in mind that the starter we use is a light duty one but its rating is 1.2 KW. With a typical cranking voltage of 10 volts, that's 120 amps. With that kind of current, the only logical routing of the ground cable is as directly to the load as possible. Do the math. At that current level, it only takes about .008 ohms to drop your working voltage a full 1 volt. That's 10% of your cranking power lost. Rotaries are especially sensitive to cranking speed because they los= e more compression than piston engines at low speed. Low compression makes starting more difficult. Losses in this circuit must be minimized for many reasons. Also note that the ground connection point that many have said they are using goes very near the crank sensor and its wiring. This proximity makes inductive coupling into the CAS circuit more likely. Add all these factors up and it is not surprising that many builders have starting problems. Tracy On Tue, Nov 24, 2009 at 8:52 AM, Jeff Whaley wrote: > I=92m curious about the engine mount style you guys are using with this > voltage drop situation. > > I can=92t imagine this problem occurring with the bed-mount/aluminum plat= e > between the oil pan and engine block configuration. > > Surely a 3/8=94 or =BD=94 plate of aluminum and 20 bolts will conduct fro= m > housing to housing? - unless maybe it was anodized? > > Jeff > > > > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *O= n > Behalf Of *Mark Steitle > *Sent:* Monday, November 23, 2009 4:41 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: No start > > > > Steve, > > > > Glad you got things figured out (we were running out of suggestions). Su= re > gives one a good feeling after battling a problem for so long. BTW, I ha= ve > two grounds on my engine. One is to the front cover, one to the front si= de > housing. I'll check into moving one up to the starter. > > Mark > > On Mon, Nov 23, 2009 at 3:33 PM, Steve Brooks > wrote: > > Al & Mark, > I would say that many people may have their ground to the engine block. > Mine has been that way since I built the plane, and worked fine for three= or > four years before I started having an issue. > > I had to order a couple of new crimp connectors, so that I can make a > longer ground cable. Hopefully they will arrive before Thanksgiving, so t= hat > I can get it all hooked up over the long weekend. > > Steve Brooks > > > Al Gietzen wrote: > > > Steve, > > I read your other post on what you discovered regarding your bad ground. = I > wonder how many of us have our engine grounds tied to a bolt near the fro= nt > cover or end housing? (Mine does...) > > Mark S. > > Mine does as well =96 bolts to the front cover. I have never had a starti= ng > issue, but I have followed this discussion with interest because a couple= of > years ago I did a starting spark check and found the sparks considerably > weaker than the mode 8 (or whatever) check. I just assumed it was due to = the > voltage drawdown when the starter was running. Now it=92s worth another l= ook. > > I recall giving it some thought when doing the wiring (My EC/EM manuals > apparently predated Tracy recommended wiring diagram). I concluded that t= he > various things bolted to the engine, like the manifolds, would provide go= od > conduction paths regardless of the sealing between layers =96 and the 20B= has > a couple more layers. Both my intake and exhaust flanges are continuous a= nd > connect all the layers, and there are other things making the connection = to > the front cover, so this would be less of an issue compared to an > installation having separate flanges to each housing. > > Anyway, Steve; I=92m glad you found the problem. And thanks; it=92s a hel= p to > the rotary community, and again proves the value of a list such as this. > > Al G > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > --00c09f923194387f7b04791ef5a8 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I doubt anodizing is a factor.=A0 Keep in mind that the starter we use is a= light duty one but its rating is 1.2 KW.=A0=A0 With a typical cranking vol= tage of 10 volts, that's 120 amps.=A0 With that kind of current, the on= ly logical routing of the ground cable is as directly to the load as possib= le.=A0

Do the math.=A0 At that current level, it only takes about .008 ohms=A0= to drop your working voltage a full 1 volt.=A0 That's 10% of your cran= king power lost.=A0 Rotaries are especially sensitive to cranking speed bec= ause they lose more compression than piston engines at low speed.=A0 Low co= mpression makes starting more difficult.=A0 Losses in this circuit must be = minimized for many reasons.=A0=A0 Also note that the ground connection poin= t that many have said they are using goes very near the crank sensor and it= s wiring.=A0 This proximity makes inductive coupling into the CAS circuit m= ore likely. =A0

Add all these factors up and it is not surprising that many builders ha= ve starting problems.

Tracy =A0

O= n Tue, Nov 24, 2009 at 8:52 AM, Jeff Whaley <jwhaley@datacast.com> wrote:=

I=92m curious about the engine mount style you guys are using with this voltage drop situation.

I can=92t imagine this problem occurring with the bed-mount/aluminum plate between the oil pan and engine block configuration= .

Surely a 3/8=94 or =BD=94 plate of aluminum and 20 bolts will conduct from housing to housing?=A0 - unless maybe it was anodized?

Jeff

=A0

From:= Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle Sent: Monday, November 23, 2009 4:41 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: No start

=A0

Steve,

=A0

Glad you got things figured out (we were=A0running o= ut of=A0suggestions).=A0 Sure gives one a good feeling after battling a problem for so long.=A0 BTW, I have two grounds on my engine.=A0 One is to the front cover, one to the front side housing.=A0 I'll=A0check into moving one up to the starter.

Mark

On Mon, Nov 23, 2009 at 3:33 PM, Steve Brooks <cozy4pilot@gmail.co= m> wrote:

Al & Mark,
I would say that many people may have their ground to the engine block. Min= e has been that way since I built the plane, and worked fine for three or fou= r years before I started having an issue.

I had to order a couple of new crimp connectors, so that I can make a longe= r ground cable. Hopefully they will arrive before Thanksgiving, so that I can= get it all hooked up over the long weekend.

Steve Brooks


Al Gietzen wrote:


Steve,

I read your other post on what you discovered regarding your bad ground. I wonder how many of us have our engine grounds tied to a bolt near the front cover or end housing? (Mine does...)

Mark S.

Mine does as well =96 bolts to the front cover. I have never had a starting issue, but I have followed this discussion with interest because a couple o= f years ago I did a starting spark check and found the sparks considerably we= aker than the mode 8 (or whatever) check. I just assumed it was due to the volta= ge drawdown when the starter was running. Now it=92s worth another look.

I recall giving it some thought when doing the wiring (My EC/EM manuals apparently predated Tracy recommended wiring diagram). I concluded that the various things bolted to the engine, like the manifolds, would provide good conduction paths regardless of the sealing between layers =96 and the 20B has a couple more layers. Both my intake and exhaust flanges are continuous= and connect all the layers, and there are other things making the connection to= the front cover, so this would be less of an issue compared to an installation having separate flanges to each housing.

Anyway, Steve; I=92m glad you found the problem. And thanks; it=92s a help to the rotary community, and again proves the value of a list such as this.

Al G



--
Homepage: =A0http:/= /www.flyrotary.com/
Archive and UnSub: =A0 http://mail.lancaironline.net:81/lists= /flyrotary/List.html

=A0


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