X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5091134 for flyrotary@lancaironline.net; Sat, 13 Aug 2011 13:42:41 -0400 Received-SPF: pass receiver=logan.com; client-ip=71.74.56.123; envelope-from=clouduster@austin.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=s3eDhkhcaTLnj7IEXy8aaXUiY7FbET0mf+/2Xe0elbc= c=1 sm=0 a=4GHctdUWtu8A:10 a=e9Fp7UO/B8F9COq9AYcbcw==:17 a=ayC55rCoAAAA:8 a=Ia-xEzejAAAA:8 a=gT77vCCP7YICf0gVxfkA:9 a=3J7Z3_OqcqWJ7tYlwCUA:7 a=wPNLvfGTeEIA:10 a=EzXvWhQp4_cA:10 a=POPnHTqErwZ9ynH7:21 a=jmo0IsgFqbcVsWMn:21 a=HZJGGiqLAAAA:8 a=pedpZTtsAAAA:8 a=o1OHuDzbAAAA:8 a=pfw2N1Jh3y64pbL128AA:9 a=tx5Nv_EejQMaZKEq70kA:7 a=tXsnliwV7b4A:10 a=HeoGohOdMD0A:10 a=eJojReuL3h0A:10 a=ILCZio5HsAgA:10 a=e9Fp7UO/B8F9COq9AYcbcw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 66.68.41.170 Received: from [66.68.41.170] ([66.68.41.170:56506] helo=DWHPC) by hrndva-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 6C/93-02568-F67B64E4; Sat, 13 Aug 2011 17:42:08 +0000 Message-ID: From: "Dennis Havarlah" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: vapor lock Date: Sat, 13 Aug 2011 12:41:58 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0184_01CC59B6.63F9D8A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 This is a multi-part message in MIME format. ------=_NextPart_000_0184_01CC59B6.63F9D8A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Right On Kelly!! I have the fuel system Kelly described in my RV-7A. I've used Mogas = with and without ethanol with outdoor temperatures up to 105 ' F. I have never had a vapor lock problem. After stopping for fuel and the = engine compartment heat soaks I hear the vapors being pushed out of the = fuel rails and thru the bypass orifice when I turn on the pumps. No = Hot Start Problems!! It takes less than 5 seconds for the vapors to be = removed and returned to the tank. That means that all the injectors see = is cool fuel when I start the engine. =20 My fuel pumps are located on the floor between the pilot and passenger. = Because the pumps are very low fuel from the left tank will flow into = the pumps by gravity. One -6 aluminum fuel line from the pumps runs to = the firewall. If any fuel leaks during flight I will smell it and turn = off the pumps and start gliding. If I have a leak in the engine = compartment I may not detect it before it ignites. Just my two cents worth. It does work for me. Dennis H. ----- Original Message -----=20 From: Kelly Troyer=20 To: Rotary motors in aircraft=20 Sent: Saturday, August 13, 2011 9:22 AM Subject: [FlyRotary] Re: vapor lock Guys, I vote for keeping high pressure pumps as close to the tanks and as = low=20 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 pumps (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 to clear the high pressure supply lines from pump = to=20 the regulator............One more thing I would install the regulator = after the=20 fuel rails/injectors to allow any vapor to pass through the rails on = their way=20 to the bypass oriface...........I have seen some fuel regulator = installations=20 with the fuel rails "Dead Ended" after the regulator leaving vapor = trapped in the rail.................When flying vapor might clear with only an = apparent=20 misfire to the pilot but after shutdown and after heat soak it could = cause=20 "Hot Start" problems (has anyone tryed to hot-start an fuel injected = "Lyc" lately............IMHO=20 Kelly Troyer "DYKE DELTA JD2" (Eventually) "13B ROTARY"_ Engine "RWS"_RD1C/EC2/EM2 "MISTRAL"_Backplate/Oil Manifold "TURBONETICS"_TO4E50 Turbo From: Ed Anderson To: Rotary motors in aircraft Sent: Saturday, August 13, 2011 8:16 AM Subject: [FlyRotary] Re: vapor lock No question, Charlie - the more of your fuel line kept under EFI pump = level pressures , the less chance for vapor lock. 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 decided 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 can = prevent vapor lock (based on my own personal experience with my unique = installation) Ed From: Charlie England=20 Sent: Saturday, August 13, 2011 9:06 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: vapor lock The really frustrating thing about all this is that every installation = is different (not to mention that it's only speculation as to what = caused this particular power loss). Sixties-era cars (carb, engine mounted fuel pump) had vapor lock = problems all the time in hot weather. Modern 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 path. Van recommends 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 high = under-cowl temps. There's a guy flying an injected Lyc on ethanol-laced = mogas who never has a problem with vapor lock. He removed the mech pump = and uses wingroot mounted electric pumps. If it weren't for the 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 =20 On 08/13/2011 06:20 AM, Ed Anderson wrote:=20 I should have added - the best overall approach - returning hot fuel = to the heat-sink tanks and drawing new cooler fuel into the lines. Ed From: Ed Anderson=20 Sent: Saturday, August 13, 2011 6:47 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: vapor lock Ok, Finn, that was my guess as well.=20 That then brings up a question - my understanding of "vapor lock" = is that it is caused by a low pressure area/combined with hot fuel on = the EFI pump intake which 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 the pump (reducing pressure on = that side), vapor can form there as well. In any case, insufficient = fuel is injected into the engine. Since the injectors are still clicking open, it would seem that any = vapor on that side of the pump already has a chance to vacate the line = (through the injector) - 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 the low pressure side (pump inlet) and thereby = permitting liquid fuel to be pumped that "cures" a vapor lock situation. = =20 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 pressure 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 for 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 pressure = side prevents vapor lock. 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 increase the pressure in the low pressure line = forcing the vapor back into the liquid - ergo - use a boost pump. FWIW Ed From: Finn Lassen=20 Sent: Saturday, August 13, 2011 2:53 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: vapor lock Hi Ed, 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. Finn On 8/10/2011 9:28 AM, Ed Anderson wrote:=20 The one I potential preventive measure/fix I have not 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? ------=_NextPart_000_0184_01CC59B6.63F9D8A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Right On Kelly!!
 
I have the fuel system Kelly = described in my=20 RV-7A.  I've used Mogas with and without ethanol with outdoor = temperatures=20 up to 105 ' F.
 
I have never had a vapor lock = problem.  After=20 stopping for fuel and the engine compartment  heat soaks I hear the = vapors=20 being pushed out of the fuel rails and thru the bypass orifice =  when I turn=20 on the pumps.  No Hot Start Problems!!  It takes less than 5 = seconds=20 for the vapors to be removed and returned to the tank.  That means = that all=20 the injectors see is cool fuel when I start the engine.  =
 
My fuel pumps are located on the floor = between the=20 pilot and passenger.  Because the pumps are very low fuel from the = left=20 tank will flow into the pumps by gravity.   One -6 aluminum = fuel line=20 from the pumps runs to the firewall.  If any fuel leaks during = flight I=20 will smell it and turn off the pumps and start gliding.  If I have = a leak=20 in the engine compartment I may not detect it before it = ignites.
 
Just my two cents worth.  It does = work for=20 me.
 
Dennis H.
 
 
 
 
----- Original Message -----
From:=20 Kelly = Troyer
Sent: Saturday, August 13, 2011 = 9:22=20 AM
Subject: [FlyRotary] Re: vapor = lock

Guys,
 
I vote for = keeping high=20 pressure pumps as close to the tanks and as low
as possible to = fuel=20 level...............I would not locate pumps and/or suppy
hoses firewall forward=20 unless totally = encapulated, insulated=20 and cooled
by ram = air...........And by=20 all means use the bypass oriface...........Besides
helping to = reprime pumps=20 (as Mark says) it will relieve pressure on leaky
injectors to = prevent=20 flooding (if you have experienced this with the 13B
you know what I = mean and=20 the Renesis is even worse to clear) and to
allow a vapor = lock to clear=20 the high pressure supply lines from pump to
the=20 regulator............One more thing I would install the regulator = after=20 the
fuel = rails/injectors to=20 allow any vapor to pass through the rails on their way
to the bypass=20 oriface...........I have seen some fuel regulator installations=20
with the fuel = rails "Dead=20 Ended" after the regulator leaving vapor trapped
in the=20 rail.................When flying vapor might clear with only an = apparent
misfire to the = pilot=20 but after shutdown and after heat soak it could cause
"Hot Start" = problems (has=20 anyone tryed to hot-start an fuel injected  "Lyc"
lately............IMHO 
 
Kelly Troyer
"DYKE DELTA JD2" (Eventually)
"13B ROTARY"_ = Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil=20 Manifold
"TURBONETICS"_TO4E50 Turbo

From: Ed Anderson=20 <eanderson@carolina.rr.com>
To: Rotary motors in aircraft=20 <flyrotary@lancaironline.net>
Sent: Saturday, August 13, 2011 = 8:16=20 AM
Subject: = [FlyRotary] Re:=20 vapor lock

No question, Charlie - the more of = your fuel=20 line kept under EFI pump level pressures , the less chance for vapor=20 lock.  In tank pumps certainly do that - but, as you point out = there are=20 other considerations.  Wing root sounds like a pretty good = compromise in=20 luie  of in-tank pumps.  I considered that but in the end = decided=20 against it as it would have high pressure fuel lines inside my cockpit = - which=20 I personally do not favor {:>)
 
Don't know for certain (and may never) the = cause of the=20 latest sputtering engine event - but, in absence of in-tank pumps = and/or=20 return to tank - I still believe that pressure applied by a boost pump = can=20 prevent vapor lock (based on my own personal experience with my unique = installation)
 
Ed

From: Charlie England
Sent: Saturday, August 13, 2011 9:06 AM
To: Rotary motors in = aircraft=20
Subject: [FlyRotary] Re: vapor lock

The really frustrating thing about all this is that = every=20 installation is different (not to mention that it's only speculation = as to=20 what caused this particular power loss).

Sixties-era cars = (carb, engine=20 mounted fuel pump) had vapor lock problems all the time in hot = weather. Modern=20 cars, almost never (in-tank high pressure pump). Keeping the pumps as = low=20 & as close to the tank(s) as practical would seem to be the best = path. Van=20 recommends mounting pumps on the floor in the cabin. That means that = the max=20 lift would be maybe 3-4 inches, through a -6 line, and nowhere near = the high=20 under-cowl temps. There's a guy flying an injected Lyc on = ethanol-laced mogas=20 who never has a problem with vapor lock. He removed the mech pump and = uses=20 wingroot mounted electric pumps.

If it weren't for the = maintenance=20 related inconveniences, I'd seriously consider in-tank pumps, as = others have=20 done.

But we still don't know whether this is what caused the = recent=20 power loss....

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

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

Ok, Finn,  that was my guess as=20 well. 
 
 That then brings up a question - my=20 understanding of "vapor lock" is that it is caused by a low pressure = area/combined with hot fuel on the EFI pump intake which cause the = gasoline=20 to flash to vapor - naturally the EFI pumps can not pump vapor - = therefore=20 as fuel is injected from the high pressure side of the pump = (reducing=20 pressure on that side), vapor can form there as well.  In any = case,=20 insufficient fuel is injected into the engine.
 
Since the injectors are still clicking open, = it would=20 seem that any vapor on that side of the pump already has a chance to = vacate=20 the line (through the injector) - so my assessment is that it = is not=20 the relief of vapor/gas from the high pressure side that remedies = the=20 problem, it's removing the gas from the low pressure side (pump = inlet) and=20 thereby permitting liquid fuel to be pumped that "cures" a vapor = lock=20 situation. 
 
So I am puzzled why a gas vent on the high = pressure=20 side would have much (if any) effect on vapor lock.  IF there = is=20 pressure on the injector side - I question whether it would be as = high as=20 pump pressure - and even if it were, the injector opening would = provide a=20 path for it to be release - not to mention the pressure = regulator.  So=20 as I said -I'm a bit puzzled as to the mechanism that a vent in the = high=20 pressure side prevents vapor lock.
 
In my opinion, there are two ways to = reduce/eliminate=20 the vapor in the low pressure side - either cool the fuel = sufficiently=20 (somewhat difficult to do) or to increase the pressure in the low = pressure=20 line forcing the vapor back into the liquid - ergo - use  a = boost=20 pump.
 
FWIW
 
Ed
 

From: Finn Lassen
Sent: Saturday, August 13, 2011 2:53 AM
To: Rotary motors in = aircraft=20
Subject: [FlyRotary] Re: vapor lock

Hi Ed,

I believe it's simply a return to the = tank from=20 the high-pressure side via a very small orifice. How small I do not=20 know.

Finn

On 8/10/2011 9:28 AM, Ed Anderson wrote: =
 
The one I potential preventive measure/fix = I have=20 not looked into is the vapor by-pass/dump that I know a few folks = are=20 using.  I search the archive but could not find a description = of this=20 method - anyone care to provide=20 = one?




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