X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5091181 for flyrotary@lancaironline.net; Sat, 13 Aug 2011 15:54:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=71.74.56.124; envelope-from=clouduster@austin.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=Pm0sEXe2MdIPK/rOEC7hwDW84D/yDsPO3JtCzsVYOFU= c=1 sm=0 a=4GHctdUWtu8A:10 a=e9Fp7UO/B8F9COq9AYcbcw==:17 a=ayC55rCoAAAA:8 a=Ia-xEzejAAAA:8 a=qonv0bnf257Hh0pRP_8A:9 a=9T0IludKn5jO7R8FFtoA:7 a=wPNLvfGTeEIA:10 a=EzXvWhQp4_cA:10 a=3nq_bZCwJJONl-ka:21 a=B9kzL7qEQLCzeCtr:21 a=CjxXgO3LAAAA:8 a=HZJGGiqLAAAA:8 a=pedpZTtsAAAA:8 a=o1OHuDzbAAAA:8 a=UB_yj13Gl2SHA9GT4RwA:9 a=U_0-0VfiBCoDHWtH4EUA:7 a=tXsnliwV7b4A:10 a=rC2wZJ5BpNYA: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] ([66.68.41.170:56745] helo=DWHPC) by hrndva-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 41/07-20593-E46D64E4; Sat, 13 Aug 2011 19:53:50 +0000 Message-ID: <43B71F486CAB44FC958D0D53D50502F5@DWHPC> From: "Dennis Havarlah" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: vapor lock Date: Sat, 13 Aug 2011 14:53:40 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01B4_01CC59C8.CA27D0C0" 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_01B4_01CC59C8.CA27D0C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Tom, I have no fuel valves. I copied Tracy's method - feed the high pressure = fuel injection pumps from the left tank. I use a Faust low pressure = pump to transfer fuel from the right tank to the left tank. I use the = EM-2 with it's 7 minute timer to remind me to turn off the transfer = pump. I use one GM auto filter on the outlet of each fuel injection = pump. The pumps are in parallel. To change the fuel filters I first = run the left tank low and than drain most of the remaining fuel. My .020 orifice discharge and the pressure regulator return flow both go = to a -4 return line that is "T" ed into the Faust discharge line to the = left tank. Dennis H. ----- Original Message -----=20 From: Tom Walter=20 To: Rotary motors in aircraft=20 Sent: Saturday, August 13, 2011 1:51 PM Subject: [FlyRotary] Re: vapor lock Dennis, What fuel valve are you using? My plans on the Bearhawk (high wing taildragger): Left and Right fuel lines flow into a "R-Both-L-off" single Andair = valve. Then to the gascolator (low point at rest) Gascolator feeds header tank, then into two pumps (only one in = flight). Everything is under the floor of the planer, under a 0.032" 2024 floor = board. Fuel return though a small "T" (0.020" orifice) to header tank. Where does the regulator return fuel to? =20 With the high wing, any air bubble from the header tank should work = it's way back up the line into the tank. -6 aluminum tubing (note tanks have = for and aft pickups, that meet up under the door. Allow for flow at high = angles of attack. Tom -------------------------------------------------------------------------= ----- From: Dennis Havarlah To: Rotary motors in aircraft Sent: Saturday, August 13, 2011 12:41 PM Subject: [FlyRotary] Re: vapor lock 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_01B4_01CC59C8.CA27D0C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Tom,
 
I have no fuel valves.  I copied = Tracy's=20 method - feed the high pressure fuel injection pumps from the left = tank.  I=20 use a Faust low pressure pump to transfer fuel from the right tank to = the left=20 tank.  I use the EM-2 with it's 7 minute timer to remind me to = turn=20 off the transfer pump.  I use one GM auto filter on the outlet = of each=20 fuel injection pump.  The pumps are in parallel.  To change = the fuel=20 filters I first run the left tank low and than drain most of the = remaining=20 fuel.
 
My .020 orifice discharge and the=20 pressure regulator return flow both go to a -4 return line that is = "T" ed=20 into the Faust discharge line to the left tank.
 
Dennis H.
----- Original Message -----
From:=20 Tom=20 Walter
Sent: Saturday, August 13, 2011 = 1:51=20 PM
Subject: [FlyRotary] Re: vapor = lock

Dennis,

What fuel valve are you using?

My plans on the Bearhawk (high wing = taildragger):

Left and Right fuel lines flow into a "R-Both-L-off" single = Andair=20 valve.

Then to the gascolator (low point at rest)

Gascolator feeds header tank, then into two pumps (only one = in=20 flight).

Everything is under the floor of the planer, under a 0.032" = 2024=20 floor board.

Fuel return though a small "T" (0.020" orifice) to header=20 tank.

Where does the regulator return fuel to? 

With the high wing, any air bubble from the header tank should = work it's=20 way
back up the line into the tank.  -6 aluminum tubing (note = tanks have=20 for and
aft pickups, that meet up under the door.  Allow for flow at = high=20 angles of
attack.

Tom






From: Dennis Havarlah=20 <clouduster@austin.rr.com>
To: Rotary motors in aircraft=20 <flyrotary@lancaironline.net>
Sent: Saturday, August 13, 2011 = 12:41=20 PM
Subject: = [FlyRotary] Re:=20 vapor lock

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=20 temperatures up to 105 ' F.
 
I have never had a vapor lock = problem. =20 After stopping for fuel and the engine compartment  heat soaks I = hear the=20 vapors being pushed out of the fuel rails and thru the bypass orifice=20  when I turn on the pumps.  No Hot Start Problems!!  It = takes=20 less than 5 seconds for the vapors to be removed and returned to the=20 tank.  That means that all the injectors see is cool fuel when I = start=20 the engine. 
 
My fuel pumps are located on the = floor between=20 the pilot and passenger.  Because the pumps are very low fuel = from the=20 left tank will flow into the pumps by gravity.   One -6 = aluminum=20 fuel line from the pumps runs to the firewall.  If any fuel leaks = during=20 flight I will smell it and turn off the pumps and start gliding.  = If I=20 have a leak in the engine compartment I may not detect it before it=20 ignites.
 
Just my two cents worth.  It = does work for=20 me.
 
Dennis H.
 
 
 
 
----- Original Message -----
To: Rotary motors in = aircraft=20
Sent: Saturday, August 13, = 2011 9:22=20 AM
Subject: [FlyRotary] Re: = vapor=20 lock

Guys,
 
I vote for keeping high pressure pumps as close to the = tanks and=20 as low
as possible to fuel level...............I would not = locate pumps=20 and/or suppy
hoses firewall forward unless totally=20 encapulated, insulated and cooled
by ram air...........And by all means use the bypass=20 oriface...........Besides
helping to reprime pumps (as Mark says) it will relieve = pressure=20 on leaky
injectors to prevent flooding (if you have experienced = this with=20 the 13B
you know what I mean and the Renesis is even worse to = clear) and=20 to
allow a vapor lock to clear the high pressure supply=20 lines from pump to
the regulator............One more thing I would install = the=20 regulator after the
fuel rails/injectors to allow any vapor to pass through = the rails=20 on their way
to the bypass oriface...........I have seen some fuel=20 regulator installations
with the fuel rails "Dead Ended" after the regulator = leaving=20 vapor trapped
in the rail.................When flying vapor might clear = with=20 only an apparent
misfire to the pilot but after shutdown and after = heat soak=20 it could cause
"Hot Start" problems (has 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 = <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 = lock.  In tank pumps certainly do that - but, as you point out = there=20 are other considerations.  Wing root sounds like a pretty good=20 compromise in luie  of in-tank pumps.  I considered that = but in=20 the end decided against it as it would have high pressure fuel lines = inside=20 my cockpit - which I personally do not favor {:>)
 
Don't know for certain (and may never) the = cause of=20 the 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=20 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,=20 engine mounted fuel pump) had vapor lock problems all the time in = hot=20 weather. Modern cars, almost never (in-tank high pressure pump). = Keeping the=20 pumps as low & as close to the tank(s) as practical would seem = to be the=20 best path. Van recommends mounting pumps on the floor in the cabin. = That=20 means that the max lift would be maybe 3-4 inches, through a -6 = line, and=20 nowhere near the high under-cowl temps. There's a guy flying an = injected Lyc=20 on ethanol-laced mogas who never has a problem with vapor lock. He = removed=20 the mech pump and uses wingroot mounted electric pumps.

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

But we still don't know whether = this is=20 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 -=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=20 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 -=20 therefore as fuel is injected from the high pressure side of the = pump=20 (reducing pressure on that side), vapor can form there as = well.  In=20 any case, insufficient fuel is injected into the = engine.
 
Since the injectors are still clicking = open, it=20 would seem that any vapor on that side of the pump already has a = chance to=20 vacate the line (through the injector) - so my assessment is = that it=20 is not the relief of vapor/gas from the high pressure side that = remedies=20 the problem, it's removing the gas from the low pressure side = (pump inlet)=20 and 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. =20 So as I said -I'm a bit puzzled as to the mechanism that a vent in = the=20 high pressure side prevents vapor lock.
 
In my opinion, there are two ways to=20 reduce/eliminate the vapor in the low pressure side - either cool = the fuel=20 sufficiently (somewhat difficult to do) or to increase the = pressure in the=20 low pressure line forcing the vapor back into the liquid - ergo -=20 use  a boost 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=20 from 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=20 this method - anyone care to provide=20 = one?






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