Return-Path: Received: from [65.54.168.115] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.3c1) with ESMTP id 741576 for flyrotary@lancaironline.net; Wed, 16 Feb 2005 12:48:45 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.168.115; envelope-from=lors01@msn.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Wed, 16 Feb 2005 09:48:00 -0800 Message-ID: Received: from 4.174.3.22 by BAY3-DAV11.phx.gbl with DAV; Wed, 16 Feb 2005 17:47:17 +0000 X-Originating-IP: [4.174.3.22] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Bad day at the airport Date: Wed, 16 Feb 2005 12:47:11 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0073_01C51425.A258C800" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0011.1703 Seal-Send-Time: Wed, 16 Feb 2005 12:47:12 -0500 X-OriginalArrivalTime: 16 Feb 2005 17:48:00.0216 (UTC) FILETIME=[A7EBFD80:01C5144F] This is a multi-part message in MIME format. ------=_NextPart_000_0073_01C51425.A258C800 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I agree with everything Jim is saying about alcohol, auto fuel & vapor = pressure. =20 But I want to stress that there is absolutely no reason you should have = to worry about these things if your fuel system follows a few simple = guidelines. The first of which is KEEP IT SIMPLE! A car's fuel system = is pretty simple and there are millions of them operating with no vapor = lock problems, including people who drive at high altitudes. None of = the people driving cars ever even thinks about whether there is alcohol = in the fuel or not. I don't either, even in my airplane. The issue of composite compatibility with alcohol is a separate = question. After experiencing problems with a couple of aircraft fuel = tank sloshing compounds, I distrust all of them. The only fuel sealing = agent I trust are the polysulfide compounds. ProSeal is one brand of = polysulfide sealant but there are others. It is impervious to anything = you might find in any fuel, including the stuff formed when alcohol is = mixed with water. Tracy ----- Original Message -----=20 From: Jim Sower=20 To: Rotary motors in aircraft=20 Sent: Wednesday, February 16, 2005 1:33 AM Subject: [FlyRotary] Re: Bad day at the airport Paul wrote: Hi, Jim....yes, I use the same gasoline as I use in my car. (Regular = unleaded). I think Tracy and Ed Anderson also use it, as they mentioned = that their spark plug life is greatly deteriorated when they are forced = to use 100LL. Guys, please step in here and correct me if I am wrong. Right so far. Unleaded is MUCH better for your engine than Avgas. Regarding alcohol, I am not overly concerned with it. I coated = my fuel tanks with 3 coats of the fuel tank sealant that comes with the = kit. (Smells like dead fish). It is supposed to be imperviant to auto = fuel and alcohol. Alcohol is not bad for composites. Water is not bad for composites. = Alcohol and water mixed is VERY corrosive to composites. If you have = alcohol, you WILL end up with some alcohol / water mixed. The stuff you = used on your tanks might be OK if it doesn't leak AT ALL, but how do you = find that out? Your "bad day" keeps sounding like vapor lock, and some = Autogas is much more volatile (read prone to vapor lock) than Avgas. = You need to check a bunch of suppliers around and determine the vapor = pressure of the gas they're delivering to their clients. You want the = lowest number you can get. Avgas has a VP of 6.0 or so. Some unleaded = is down around 7. Some more could be over 10. That's where you get = into cavitation / vapor lock / etc. problems. =20 Alcohol might very well not be a factor where you live, but in any = event it's very easy to detect. =20 Time will tell. Paul Conner ----- Original Message -----=20 From: Jim Sower=20 To: Rotary motors in aircraft=20 Sent: Tuesday, February 15, 2005 12:28 AM Subject: [FlyRotary] Re: Bad day at the airport <... I was using auto fuel (regular). I have a fuel return line = and it goes ...> DAMN. I hadn't heard about that. Paul, that's a really important = factor. Maybe I lost it in all the chatter going on. Auto fuel can be = pretty close to avgas in volatility (Vapor Pressure) but for the most = part it's anyone's guess. Avgas is regulated at max~ 6 psi Vapor = Pressure. Mogas used to get as high as 16-20 psi VP. That high a = pressure can petty much guarantee vapor lock under high under hood / = cowl conditions. As time went on and more and more cars got MPFI and = environmental regulations progressed, Mogas vapor pressures came down = some. IIRC Calif has a 7-8 psi max vapor pressure, and places with = strict environmental regulations (like cities who aren't making their = air quality numbers) are more likely to require lower VPs. Trouble is, = VP can vary widely across various sources of Mogas. I would guess that anywhere that requires gas pump nozzles that = capture vapor as you fill your tank will have lower VPs, but sadly, they = are also most likely to have alcohol added to mogas. Alcohol is a major = NO NO for aircraft. Mogas fuel systems should be very carefully = designed to prevent vapor lock or you are apt to get into some VERY = SERIOUS SHIT!!. Like there have been maybe 80,000 Mogas STCs issued to = Lycs and Conts. NONE to ANY certified engine that's injected. Which is not to say that you can't make a system that runs = reliably with higher VP Mogas, but you need to be very VERY attentive to = the issue, both in design and operation. You also have to figure out a = way to find out what local VPs are. Alcohol is easy to detect and = distributors know how much they're adding to the fuel. Good info on VP = is more difficult to come by and it might vary some from one distributor = to another. I've been researching Mogas and recently gave a little = presentation to my EAA chapter and a couple of flying clubs. It's = wonderful stuff for your engine (lead is really terrible) but you need = to be very careful to not allow ANY alcohol into your airplane and be = very careful about checking and monitoring VP. Unleaded Avgas is coming, but VP will be an issue with it ... Jim = S. Mark R Steitle wrote:=20 Paul, It looks like the group has focused in on the fuel system, or = more specifically the sump tank as the likely culprit. I suspected you = might have been running mogas. Its my understanding that auto fuel has = a much lower vapor pressure than avgas and is therefore more likely to = vapor lock. =20 Just a SWAG, but I think the engine and related systems got hot = enough to heat the fuel in the fuel rails so that once it passed the = pressure regulator (pressure drop) it started to boil, similar to when = you open a hot soda. With the return fuel going to an unvented tank, = the boiling fuel expanded enough to cause pressure in the header tank so = as to prevent fresh fuel from flowing into the tank. Eventually, the = header tank ran dry and the engine quit. You sure handled the situation = like a pro. Hope I never have to face that scenario. Mark S.=20 =20 Hi, Mark...my humblest appologies for taking so long to respond. = I am whittling down the 200 plus messages in my inbox. I was using = auto fuel (regular). I have a fuel return line and it goes to the top of = my aluminum sump tank that is located on the cool side of the firewall = (inside the cabin, behind the rear seat). The return line is -8 in size. = Hope this helps. Paul Conner -------------------------------------------------------------------------= - No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.7 - Release Date: = 2/10/2005 -------------------------------------------------------------------------= --- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005 = -------------------------------------------------------------------------= --- Homepage: http://www.flyrotary.com/ Archive: = http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_000_0073_01C51425.A258C800 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I agree with everything Jim is saying about alcohol, auto = fuel=20 & vapor pressure. 
 
But I want to stress that there is absolutely no reason you should = have to=20 worry about these things if your fuel system follows a few simple=20 guidelines.  The first of which is KEEP IT SIMPLE!   A = car's fuel=20 system is pretty simple and there are millions of them operating with no = vapor=20 lock problems, including people who drive at high altitudes. =20    None of the people driving cars ever even thinks = about=20 whether there is alcohol in the fuel or not.  I don't either, even = in my=20 airplane.
 
The issue of composite compatibility with alcohol is a separate=20 question.  After experiencing problems with a couple of aircraft = fuel tank=20 sloshing compounds, I distrust all of them.  The only fuel sealing = agent I=20 trust are the polysulfide compounds.  ProSeal is one brand of = polysulfide=20 sealant but there are others.  It is impervious to anything you = might find=20 in any fuel, including the stuff formed when alcohol is mixed with = water.
 
Tracy
----- Original Message -----
From: Jim Sower
To: Rotary motors in = aircraft
Sent: Wednesday, February 16, = 2005 1:33=20 AM
Subject: [FlyRotary] Re: Bad = day at the=20 airport

Paul wrote:
Hi, Jim....yes, I use the same = gasoline as I=20 use in my car. (Regular unleaded).  I think Tracy and Ed = Anderson also=20 use it, as they mentioned that their spark plug life is greatly = deteriorated=20 when they are forced to use 100LL.  Guys, please step in here = and=20 correct me if I am wrong.
Right=20 so far.  Unleaded is MUCH better for your engine than = Avgas.
      = Regarding=20 alcohol, I am not overly concerned with it. I coated my fuel tanks = with 3=20 coats of the fuel tank sealant that comes with the kit. (Smells like = dead=20 fish). It is supposed to be imperviant to auto fuel and=20 alcohol.
Alcohol is not = bad for=20 composites.  Water is not bad for composites.  Alcohol and = water=20 mixed is VERY corrosive to composites.  If you have alcohol, you = WILL end=20 up with some alcohol / water mixed.  The stuff you used on your = tanks=20 might be OK if it doesn't leak AT ALL, but how do you find that = out? =20 Your "bad day" keeps sounding like vapor lock, and some Autogas is = much more=20 volatile (read prone to vapor lock) than Avgas.  You need to = check a=20 bunch of suppliers around and determine the vapor pressure of the gas = they're=20 delivering to their clients.  You want the lowest number you can=20 get.  Avgas has a VP of 6.0 or so.  Some unleaded is down = around=20 7.  Some more could be over 10.  That's where you get into=20 cavitation / vapor lock / etc. problems. 

Alcohol might = very well=20 not be a factor where you live, but in any event it's very easy to=20 detect. 
  Time will tell.  Paul=20 Conner
 
-----=20 Original Message -----
From:=20 Jim Sower To:=20 Rotary motors in = aircraft=20 Sent:=20 Tuesday, February 15, 2005 12:28 AM Subject:=20 [FlyRotary] Re: Bad day at the airport

<... I was using = auto fuel=20 (regular). I have a fuel return line and it goes=20 ...>

DAMN.  I hadn't heard about that.  Paul, = that's a=20 really important factor.  Maybe I lost it in all the chatter = going=20 on.  Auto fuel can be pretty close to avgas in = volatility=20 (Vapor Pressure) but for the most part it's anyone's guess.  = Avgas is=20 regulated at max~ 6 psi Vapor Pressure.  Mogas used to = get as=20 high as 16-20 psi VP.  That high a pressure can petty much = guarantee=20 vapor lock under high under hood / cowl conditions.  As time = went on=20 and more and more cars got MPFI and environmental regulations = progressed,=20 Mogas vapor pressures came down some.  IIRC Calif has a 7-8 = psi max=20 vapor pressure, and places with strict environmental regulations = (like=20 cities who aren't making their air quality numbers) are more = likely to=20 require lower VPs.  Trouble is, VP can vary widely across = various=20 sources of Mogas.

I would guess that anywhere that requires = gas=20 pump nozzles that capture vapor as you fill your tank will have = lower VPs,=20 but sadly, they are also most likely to have alcohol added to = mogas. =20 Alcohol is a major NO NO for aircraft.  Mogas fuel systems = should be=20 very carefully designed to prevent vapor lock or you are apt to = get into=20 some VERY SERIOUS SHIT!!.  Like there have been maybe 80,000 = Mogas=20 STCs  issued to Lycs and Conts.  NONE to ANY certified = engine=20 that's injected.

Which is not to say that you can't make a = system=20 that runs reliably with higher VP Mogas, but you need to be very = VERY=20 attentive to the issue, both in design and operation.  You = also have=20 to figure out a way to find out what local VPs are.  Alcohol = is easy=20 to detect and distributors know how much they're adding to the = fuel. =20 Good info on VP is more difficult to come by and it might vary = some from=20 one distributor to another.

I've been researching Mogas and = recently gave a little presentation to my EAA chapter and a couple = of=20 flying clubs.  It's wonderful stuff for your engine (lead is = really=20 terrible) but you need to be very careful to not allow ANY alcohol = into=20 your airplane and be very careful about checking and monitoring=20 VP.

Unleaded Avgas is coming, but VP will be an issue with = it ...=20 Jim S.


Mark R Steitle wrote:=20

Paul,

It = looks like=20 the group has focused in on the fuel system, or more = specifically the=20 sump tank as the likely culprit.  I suspected you might = have been=20 running mogas.  Its my understanding that auto fuel has a = much=20 lower vapor pressure than avgas and is therefore more likely to = vapor=20 lock. 

Just = a SWAG,=20 but I think the engine and related systems got hot enough to = heat the=20 fuel in the fuel rails so that once it passed the pressure = regulator=20 (pressure drop) it started to boil, similar to when you open a = hot=20 soda.  With the return fuel going to an unvented tank, the = boiling=20 fuel expanded enough to cause pressure in the header tank so as = to=20 prevent fresh fuel from flowing into the tank.  Eventually, = the=20 header tank ran dry and the engine quit.  You sure handled = the=20 situation like a pro.  Hope I never have to face that=20 scenario.

Mark = S.=20

 =20

Hi, Mark...my = humblest=20 appologies for taking so long to respond.  I am whittling = down the=20 200 plus messages in my inbox.  I was using auto fuel = (regular). I=20 have a fuel return line and it goes to the top of my aluminum = sump tank=20 that is located on the cool side of the firewall (inside the = cabin,=20 behind the rear seat). The return line is -8 in size.  Hope = this=20 helps.  Paul=20 Conner

No virus found in this incoming message.
Checked by AVG=20 Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.7 - = Release Date:=20 2/10/2005

No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005
  

  
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