X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from EXHUB003-2.exch003intermedia.net ([207.5.74.29] verified) by logan.com (CommuniGate Pro SMTP 5.3c2) with ESMTPS id 3988385 for flyrotary@lancaironline.net; Tue, 24 Nov 2009 15:44:55 -0500 Received-SPF: none receiver=logan.com; client-ip=207.5.74.29; envelope-from=jwhaley@datacast.com Received: from EXVMBX003-5.exch003intermedia.net ([207.5.74.45]) by EXHUB003-2.exch003intermedia.net ([207.5.74.29]) with mapi; Tue, 24 Nov 2009 12:44:18 -0800 From: Jeff Whaley To: Rotary motors in aircraft Date: Tue, 24 Nov 2009 12:46:35 -0800 Subject: RE: [FlyRotary] Re: No start Thread-Topic: [FlyRotary] Re: No start Thread-Index: AcptFIozJbAm4jnVQQiHIVnF28HqpgAH+xmg Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BCF26EXVMBX0035e_" MIME-Version: 1.0 --_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BCF26EXVMBX0035e_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Good point on the anodizing Tracy; also a .005" layer of silicone isn't con= ductive either, even with bare aluminum - conduction is made through the bo= lts and not the entire mating surface of the plate. The math checks out to= o. I'm still curious about their specific setups though; I can see how a s= tack of aluminum/iron/aluminum, etc with a layer of hylomar in between each= stack might not be the best conductor - the sub-mount plate has to help. In my setup the battery is behind the cabin for weight and balance consider= ations. Ground is made to a steel tube frame with about 1 foot of #1 weldin= g cable; Positive runs through Master relay under the floor to firewall wit= h about 6 feet of same #1 welding cable, then another 2.5 feet to starter. = The engine ground is via stainless braid from front iron to engine mount h= ardware at the firewall/airframe. So if the starter current path is from po= st to post on the battery, then in my case it has to be close to 16 feet! = I've never had any starting problems, but it would be interesting to see if= an extra ground strap from starter bracket back to the airframe makes the = starter spin faster or engine fire sooner ... will test that and post resul= ts. Jeff From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Tracy Crook Sent: Tuesday, November 24, 2009 9:43 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: No start I doubt anodizing is a factor. Keep in mind that the starter we use is a l= ight duty one but its rating is 1.2 KW. With a typical cranking voltage o= f 10 volts, that's 120 amps. With that kind of current, the only logical r= outing 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 los= t. Rotaries are especially sensitive to cranking speed because they lose m= ore compression than piston engines at low speed. Low compression makes st= arting more difficult. Losses in this circuit must be minimized for many r= easons. Also note that the ground connection point that many have said th= ey are using goes very near the crank sensor and its wiring. This proximit= y makes inductive coupling into the CAS circuit more likely. Add all these factors up and it is not surprising that many builders have s= tarting problems. Tracy On Tue, Nov 24, 2009 at 8:52 AM, Jeff Whaley > wrote: I'm curious about the engine mount style you guys are using with this volta= ge drop situation. I can't imagine this problem occurring with the bed-mount/aluminum plate be= tween the oil pan and engine block configuration. Surely a 3/8" or =BD" plate of aluminum and 20 bolts will conduct from hous= ing to housing? - unless maybe it was anodized? Jeff 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 Steve, Glad you got things figured out (we were running out of suggestions). Sure= gives one a good feeling after battling a problem for so long. BTW, I hav= e 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. Min= e has been that way since I built the plane, and worked fine for three or f= our 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 c= an 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 - bolts to the front cover. I have never had a starting i= ssue, 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 w= eaker than the mode 8 (or whatever) check. I just assumed it was due to the= voltage drawdown when the starter was running. Now it's worth another look= . I recall giving it some thought when doing the wiring (My EC/EM manuals app= arently predated Tracy recommended wiring diagram). I concluded that the va= rious things bolted to the engine, like the manifolds, would provide good c= onduction paths regardless of the sealing between layers - 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 t= o the front cover, so this would be less of an issue compared to an install= ation having separate flanges to each housing. Anyway, Steve; I'm glad you found the problem. And thanks; it's a help to t= he 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 --_000_C03ABB0A7362B84BB53D544B3C305E0E0153A41BCF26EXVMBX0035e_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Good point on the anodizing Tracy; also a .005” layer = of silicone isn’t conductive either, even with bare aluminum – con= duction is made through the bolts and not the entire mating surface of the plate. = =A0The math checks out too.=A0 I’m still curious about their specific setups thou= gh; I can see how a stack of aluminum/iron/aluminum, etc with a layer of hylomar = in between each stack might not be the best conductor – the sub-mount pl= ate has to help.

 

In my setup the battery is behind the cabin for weight and balance considerations. Ground is made to a steel tube frame with about 1 f= oot of #1 welding cable; Positive runs through Master relay under the floor to firewall with about 6 feet of same #1 welding cable, then another 2.5 feet = to starter.=A0 The engine ground is via stainless braid from front iron to eng= ine mount hardware at the firewall/airframe. So if the starter current path is from p= ost to post on the battery, then in my case it has to be close to 16 feet!=A0 I= ’ve never had any starting problems, but it would be interesting to see if an e= xtra ground strap from starter bracket back to the airframe makes the starter sp= in faster or engine fire sooner … will test that and post results.<= /o:p>

Jeff

 

From: Rotary motors= in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Tracy Cro= ok
Sent: Tuesday, November 24, 2009 9:43 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: No start

 

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&nbs= p; to drop your working voltage a full 1 volt.  That's 10% of your cranki= ng power lost.  Rotaries are especially sensitive to cranking speed becau= se they lose more compression than piston engines at low speed.  Low compression makes starting more difficult.  Losses in this circuit mus= t be minimized for many reasons.   Also note that the ground connectio= n point that many have said they are using goes very near the crank sensor an= d its wiring.  This proximity makes inductive coupling into the CAS circ= uit 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 <jwhaley@datacast.com> wrote:

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

I can’t imagine this problem occurring with the bed-mount/aluminum plate between the oil pan and engine block configuration.

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

Jeff

 

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

 

Steve,

 

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

Mark

On Mon, Nov 23, 2009 at 3:33 PM, Steve Brooks <cozy4pilot@gmail.com= > 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 – bolts to the front cover. I have never had a star= ting 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’s 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 – and the 2= 0B 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’m glad you found the problem. And thanks; it’s= a help to the rotary community, and again proves the value of a list such as this.

Al G



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