X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nm6.access.bullet.mail.sp2.yahoo.com ([98.139.44.133] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with SMTP id 5091050 for flyrotary@lancaironline.net; Sat, 13 Aug 2011 10:23:23 -0400 Received-SPF: none receiver=logan.com; client-ip=98.139.44.133; envelope-from=keltro@att.net Received: from [98.139.44.107] by nm6.access.bullet.mail.sp2.yahoo.com with NNFMP; 13 Aug 2011 14:22:49 -0000 Received: from [98.139.44.68] by tm12.access.bullet.mail.sp2.yahoo.com with NNFMP; 13 Aug 2011 14:22:48 -0000 Received: from [127.0.0.1] by omp1005.access.mail.sp2.yahoo.com with NNFMP; 13 Aug 2011 14:22:48 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 965754.49762.bm@omp1005.access.mail.sp2.yahoo.com Received: (qmail 13540 invoked by uid 60001); 13 Aug 2011 14:22:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1313245368; bh=fI47klgnbVt6HCkEfRaJ0WhCM+z+BMzgku+3bV5UvI0=; 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Sat, 13 Aug 2011 07:22:48 PDT X-Mailer: YahooMailWebService/0.8.113.313619 References: Message-ID: <1313245368.12109.YahooMailNeo@web83906.mail.sp1.yahoo.com> Date: Sat, 13 Aug 2011 07:22:48 -0700 (PDT) From: Kelly Troyer Reply-To: Kelly Troyer Subject: Re: vapor lock To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-485267123-1313245368=:12109" --0-485267123-1313245368=:12109 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Guys,=0A=A0=0AI vote for keeping high pressure pumps as close to the tanks = and as low =0Aas possible to fuel level...............I would not locate pu= mps and/or suppy=0Ahoses=A0firewall forward unless totally encapulated,=A0i= nsulated and cooled=0Aby ram air...........And by all means use the bypass = oriface...........Besides=0Ahelping to reprime pumps (as Mark says) it will= relieve pressure on leaky=0Ainjectors to prevent flooding (if you have exp= erienced this with the 13B=0Ayou know what I mean and the Renesis is even w= orse to clear) and to=0Aallow a vapor lock to clear the high pressure suppl= y lines=A0from=A0pump to =0Athe regulator............One more thing I would= install the regulator after the =0Afuel rails/injectors to allow any vapor= to pass through the rails on their way =0Ato the bypass oriface...........= I have seen some fuel regulator=A0installations =0Awith the fuel rails "Dea= d Ended" after the regulator leaving vapor trapped=0Ain the rail...........= ......When flying vapor might clear with only an apparent =0Amisfire to the= pilot but=A0after shutdown and after heat soak it could cause =0A"Hot Star= t" problems (has anyone tryed to hot-start an fuel=A0injected=A0 "Lyc"=0Ala= tely............IMHO=A0=0A=0AKelly Troyer=0A"DYKE DELTA JD2" (Eventually)= =0A"13B ROTARY"_ Engine=0A"RWS"_RD1C/EC2/EM2=0A"MISTRAL"_Backplate/Oil Mani= fold=0A"TURBONETICS"_TO4E50 Turbo=0A=0AFrom: Ed Anderson =0ATo: Rotary motors in aircraft =0AS= ent: Saturday, August 13, 2011 8:16 AM=0ASubject: [FlyRotary] Re: vapor loc= k=0A=0A=0ANo question, Charlie=A0-=A0the more of your fuel line kept under = EFI pump level pressures , the less chance for vapor lock.=A0 In tank pumps= certainly do that - but, as you point out there are other considerations.= =A0 Wing root sounds like a pretty good compromise in luie=A0 of in-tank pu= mps.=A0 I considered that but in the end decided against it as it would hav= e high pressure fuel lines inside my cockpit - which I personally do not fa= vor {:>)=0A=A0=0ADon't know for certain (and may never) the cause of the la= test sputtering engine event - but, in absence of in-tank pumps and/or retu= rn to tank - I still believe that pressure applied by a boost pump can prev= ent vapor lock (based on my own personal experience with my unique installa= tion)=0A=0AEd=0A=0A=0AFrom: Charlie England =0ASent: Saturday, August 13, 2= 011 9:06 AM=0ATo: Rotary motors in aircraft =0ASubject: [FlyRotary] Re: vap= or lock=0AThe really frustrating thing about all this is that every install= ation is different (not to mention that it's only speculation as to what ca= used this particular power loss).=0A=0ASixties-era cars (carb, engine mount= ed fuel pump) had vapor lock problems all the time in hot weather. Modern c= ars, almost never (in-tank high pressure pump). Keeping the pumps as low & = as close to the tank(s) as practical would seem to be the best path. Van re= commends mounting pumps on the floor in the cabin. That means that the max = lift would be maybe 3-4 inches, through a -6 line, and nowhere near the hig= h under-cowl temps. There's a guy flying an injected Lyc on ethanol-laced m= ogas who never has a problem with vapor lock. He removed the mech pump and = uses wingroot mounted electric pumps.=0A=0AIf it weren't for the maintenanc= e related inconveniences, I'd seriously consider in-tank pumps, as others h= ave done.=0A=0ABut we still don't know whether this is what caused the rece= nt power loss....=0A=0ACharlie=0A=A0=0AOn 08/13/2011 06:20 AM, Ed Anderson = wrote: =0AI should have added - the best overall approach - returning hot f= uel to the heat-sink tanks and drawing new cooler fuel into the lines.=0A>= =0A>Ed=0A>=0A>=0A>From: Ed Anderson =0A>Sent: Saturday, August 13, 2011 6:4= 7 AM=0A>To: Rotary motors in aircraft =0A>Subject: [FlyRotary] Re: vapor lo= ck=0A>=0A>=0A>Ok, Finn, =A0that was my guess as well.=A0=0A>=0A>=A0That the= n brings up a question - my understanding of "vapor lock" is that it is cau= sed by a low pressure area/combined with hot fuel on the EFI pump intake wh= ich cause the gasoline to flash to vapor - naturally the EFI pumps can not = pump vapor - therefore as fuel is injected from the high pressure side of t= he pump (reducing pressure on that side), vapor can form there as well.=A0 = In any case, insufficient fuel is injected into the engine.=0A>=0A>Since th= e injectors are still clicking open, it would seem that any vapor on that s= ide of the pump already has a chance to vacate the line (through the inject= or)=A0- so my assessment is that it is not the relief of vapor/gas from the= high pressure side that remedies the problem, it's removing the gas from t= he low pressure side (pump inlet) and thereby permitting liquid fuel to be = pumped that "cures" a vapor lock situation.=A0 =0A>=0A>So I am puzzled why = a gas vent on the high pressure side would have much (if any) effect on vap= or lock.=A0 IF there is pressure on the injector side - I question whether = it would be as high as pump pressure - and even if it were, the injector op= ening would provide a path for it to be release - not to mention the pressu= re regulator.=A0 So as I said -I'm a bit puzzled as to the mechanism that a= vent in the high pressure side prevents vapor lock.=0A>=0A>In my opinion, = there are two ways to reduce/eliminate the vapor in the low pressure side -= either cool the fuel sufficiently (somewhat difficult to do) or to increas= e the pressure in the low pressure line forcing the vapor back into the liq= uid - ergo - use=A0 a boost pump.=0A>=0A>FWIW=0A>=0A>Ed=0A>=0A>=0A>=0A>From= : Finn Lassen =0A>Sent: Saturday, August 13, 2011 2:53 AM=0A>To: Rotary mot= ors in aircraft =0A>Subject: [FlyRotary] Re: vapor lock=0A>=0A>Hi Ed,=0A>= =0A>I believe it's simply a return to the tank from the high-pressure side = via a very small orifice. How small I do not know.=0A>=0A>Finn=0A>=0A>On 8/= 10/2011 9:28 AM, Ed Anderson wrote: =0A>=0A>=0A>>=0A>>The one I potential p= reventive measure/fix I have not looked into is the vapor by-pass/dump that= I know a few folks are using.=A0 I search the archive but could not find a= description of this method - anyone care to provide one?=0A> --0-485267123-1313245368=:12109 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Guys,
 
I vote for keeping h= igh pressure pumps as close to the tanks and as low
as possible to fuel = level...............I would not locate pumps and/or suppy
hoses firewall = forward unless totally encapulated, = ;insulated and cooled
by ram air..........= .And by all means use the bypass oriface...........Besides
helping to reprime p= umps (as Mark says) it will relieve pressure on leaky
injectors to prevent= flooding (if you have experienced this with the 13B
you know what I mean= and the Renesis is even worse to clear) and to
allow a vapor lock t= o clear the high pressure supply lines from pump to
the regulator.......= .....One more thing I would install the regulator after the
fuel rails/injectors= to allow any vapor to pass through the rails on their way
to the bypass orifac= e...........I have seen some fuel regulator installations
with the fuel rails = "Dead Ended" after the regulator leaving vapor trapped
in the rail.........= ........When flying vapor might clear with only an apparent
misfire to the pilot= but after shutdown and after heat soak it could cause
"Hot Start" problems= (has anyone tryed to hot-start an fuel = injected  "Lyc"
lately............I<= /SPAN>MHO 
 
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil = Manifold
"TURBONETICS"_TO4E50 Turbo

From:= Ed Anderson <eanderson@carolina.rr.com>
To: Rotary motors in aircraft <flyrota= ry@lancaironline.net>
Sent: Saturday, August 13, 2011 8:16 AM
Subject: [FlyRotary] Re: vapor lock

No question, Charlie - the more of your f= uel line kept under EFI pump level pressures , the less chance for vapor lo= ck.  In tank pumps certainly do that - but, as you point out there are= other considerations.  Wing root sounds like a pretty good compromise= in luie  of in-tank pumps.  I considered that but in the end dec= ided against it as it would have high pressure fuel lines inside my cockpit= - which I personally do not favor {:>)
 
Don't know for certain (and may never) the cause of= the latest sputtering engine event - but, in absence of in-tank pumps and/= or return to tank - I still believe that pressure applied by a boost pump c= an prevent vapor lock (based on my own personal experience with my unique i= nstallation)
 
Ed

The really frustrating thing about all this is that every in= stallation is different (not to mention that it's only speculation as to wh= at caused this particular power loss).

Sixties-era cars (carb, engin= e mounted fuel pump) had vapor lock problems all the time in hot weather. M= odern cars, almost never (in-tank high pressure pump). Keeping the pumps as= low & as close to the tank(s) as practical would seem to be the best p= ath. Van recommends mounting pumps on the floor in the cabin. That means th= at the max lift would be maybe 3-4 inches, through a -6 line, and nowhere n= ear the high under-cowl temps. There's a guy flying an injected Lyc on etha= nol-laced mogas who never has a problem with vapor lock. He removed the mec= h pump and uses wingroot mounted electric pumps.

If it weren't for t= he maintenance related inconveniences, I'd seriously consider in-tank pumps= , as others have done.

But we still don't know whether this is what caused the recent power loss....

Charlie
 
On 08= /13/2011 06:20 AM, Ed Anderson wrote:=20
I should have added - the best overall approach - r= eturning hot fuel to the heat-sink tanks and drawing new cooler fuel into t= he lines.
 
Ed

Sent: Saturday, August 13, 2011 6:47 AM
Subject: [FlyRotary] Re: vapor lock

Ok, Finn,  that was my guess as well. 
 
 That then brings up a question - my understan= ding of "vapor lock" is that it is caused by a low pressure area/combined w= ith hot fuel on the EFI pump intake which cause the gasoline to flash to va= por - naturally the EFI pumps can not pump vapor - therefore as fuel is inj= ected from the high pressure side of the pump (reducing pressure on that si= de), vapor can form there as well.  In any case, insufficient fuel is = injected into the engine.
 
Since the injectors are still clicking open, it wou= ld seem that any vapor on that side of the pump already has a chance to vac= ate the line (through the injector) - so my assessment is that it is n= ot the relief of vapor/gas from the high pressure side that remedies the pr= oblem, it's removing the gas from the low pressure side (pump inlet) and th= ereby permitting liquid fuel to be pumped that "cures" a vapor lock situati= on. 
 
So I am puzzled why a gas vent on the high pressure= side would have much (if any) effect on vapor lock.  IF there is pres= sure on the injector side - I question whether it would be as high as pump = pressure - and even if it were, the injector opening would provide a path f= or it to be release - not to mention the pressure regulator.  So as I = said -I'm a bit puzzled as to the mechanism that a vent in the high pressur= e side prevents vapor lock.
 
In my opinion, there are two ways to reduce/elimina= te the vapor in the low pressure side - either cool the fuel sufficiently (= somewhat difficult to do) or to increase the pressure in the low pressure l= ine forcing the vapor back into the liquid - ergo - use  a boost pump.=
 
FWIW
 
Ed
 

Sent: Saturday, August 13, 2011 2:53 AM
Subject: [FlyRotary] Re: vapor lock

Hi Ed,

I believe it's simply a return to the tank fro= m the high-pressure side via a very small orifice. How small I do not know.=

Finn

On 8/10/2011 9:28 AM, Ed Anderson wrote:
 
The one I potential preventive measure/fix I have n= ot looked into is the vapor by-pass/dump that I know a few folks are using.=   I search the archive but could not find a description of this method= - anyone care to provide one?




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