X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp109.sbc.mail.re2.yahoo.com ([68.142.229.96] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with SMTP id 2313241 for flyrotary@lancaironline.net; Wed, 05 Sep 2007 12:58:19 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.229.96; envelope-from=downing.j@sbcglobal.net Received: (qmail 99752 invoked from network); 5 Sep 2007 16:57:40 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=sbcglobal.net; h=Received:X-YMail-OSG:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=nTzItetiWQ134vsqarb6XuPxaRB/77S7LioivEGGgJrq3E0FJu5Ljt5yj3lz0bP/uNpMd49lVhuzuU9fD+iCiVQYIXiGH08+4y+GhNCH92BYWHZlTPJt5hZoxJBx8+Q0PC3dJtJRLm+H11m2YDn2VCMuWr6QxTYOBW8nZ0e6qC4= ; Received: from unknown (HELO mom) (downing.j@sbcglobal.net@75.40.249.3 with login) by smtp109.sbc.mail.re2.yahoo.com with SMTP; 5 Sep 2007 16:57:39 -0000 X-YMail-OSG: z6T96ZIVM1n_cBRV4Mo8_CTMAZGGmyfV2TlHKHNqk4YR__ahF4hGzVxYqbzAKhX7XKFPMJP0AwNwhy3_Z2.nX4l3iB1_lApmJGWbnhvtyXbsKl5nErRSJr5CL5e.UzvUCVIPa429PKYS..rLD3TgVLEDxg-- Message-ID: <009c01c7efde$5893ae00$4001a8c0@gateway.2wire.net> From: "John Downing" To: "flyrotary" Subject: Fw: [TailwindForum] often asked questions on gas Date: Wed, 5 Sep 2007 13:01:04 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0099_01C7EFBC.D135C2C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_0099_01C7EFBC.D135C2C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Here is a note on auto fuel in aviation that explains why the bubbles = form in the clear fuel lines. It is mentioned in the comparison of = Avgas to other fuels. Thought I would pass it along. JohnD ----- Original Message -----=20 From: Dave & Theresa Conrad=20 To: lycoming@yahoogroups.com=20 Cc: Tailwind at Yahoo=20 Sent: Monday, September 03, 2007 11:43 PM Subject: [TailwindForum] often asked questions on gas I did a google search "Lead in gas" and came up with many hits. I read = several but thought I'd post this for anyone interested to read. It = lists lead contents of 80/87 100LL and 100/130.=20 Dave Conrad Avgas is a high-octane fuel used for aircraft and, in the past, racing = cars. Avgas is a portmanteau for aviation gasoline, as distinguished = from mogas (motor gasoline), which is the everyday gasoline used in = cars. Avgas is used in aircraft that use piston or Wankel engines; gas = turbines can operate on avgas, but typically do not. Turbine and diesel = engines are designed to use kerosene-based jet fuel. [edit] Avgas properties and varieties Avgas has a lower volatility than mogas (i.e. it does not evaporate as = quickly), which can be important for high-altitude use and higher = temperatures. The particular mixtures in use today are the same as when = they were first developed in the 1950s and 1960s, and therefore the = high-octane ratings are achieved by the addition of tetra-ethyl lead = (TEL), a highly toxic substance that was phased out for car use in most = countries in the 1980s. The main petroleum component used in blending = avgas is alkylate, which is essentially a mixture of various isooctanes, = and some refineries also use some reformate. Avgas is currently available in several grades with differing maximum = lead concentrations. Since TEL is a rather expensive additive, a minimum = amount of it is typically added to the fuel to bring it up to the = required octane rating so actual concentrations are often lower than the = maximum. Jet fuel is not avgas. It is similar to kerosene and is used in turbine = engines. In Europe, environmental and cost considerations have led to = increasing numbers of aircraft being fitted with highly fuel-efficient = diesel engines; these too run on jet fuel. Civilian aircraft use Jet-A, = Jet-A1 or in severely cold climates Jet-B. There are other = classification systems for military turbine and diesel fuel. See Jet = fuel. [edit] Gasoline Gasoline used for aviation fuel generally has two numbers associated = with its octane rating. Examples of this include the (now almost = completely unavailable) 80/87 avgas, and the 100/130 avgas. The first = number indicates the octane rating of the fuel tested to "aviation lean" = standards, which is similar to the Motor Octane Number (MON) rating = given to automotive gasoline. The second number indicates the octane = rating of the fuel tested to the "aviation rich" standard, which tries = to simulate a supercharged condition with a rich mixture, elevated = temperatures, and a high manifold pressure. 100LL, spoken as "100 low lead", contains a lead based anti-knock = compound but less than the "highly-leaded" 100/130 avgas it effectively = replaced. Most piston aircraft engines require 100LL but it is scheduled = to be phased out in the United States because of the lead toxicity. An = alternative fuel has not yet been developed for these engines. While = there are similar engines that burn non-leaded fuels aircraft are often = purchased with engines that use 100LL because many airports only have = 100LL. 100LL contains a maximum of 2 grams of lead per US gallon, or = maximum 0.56 grams/litre and is the most commonly available and used = aviation gasoline. 82UL is an unleaded fuel similar to automobile gasoline but without = additives. It may be used in aircraft that have a Supplemental Type = Certificate for the use of automobile gasoline with an aviation lean = octane rating (MON) of 82 or less or an antiknock index of 87 or less. = It may not be used in engines that require 100LL. See Octane Rating. The = FAA highly recommends installing placards stating the use of 82UL is or = is not approved on those airplanes that specify unleaded autogas (mogas) = as an approved fuel[1]. Gasoline (MOGAS) may be used in aircraft that have a Supplemental Type = Certificate for automotive gasoline. Most of these applicable aircraft = have low-compression engines which were originally certified to run on = 80/87 avgas and require only "regular" 87 anti-knock index automotive = gasoline. Examples of this include the popular Cessna 172 or Piper = Cherokee with the 150 hp variant of the Lycoming O-320. Some aircraft = engines were originally certified using a 91/96 avgas and have STC's = available to run "premium" 91 anti-knock index automotive gasoline. = Examples of this include some Cherokee's with the 160 hp Lycoming O-320 = or 180 hp O-360 or the Cessna 152 with the O-235. Avgas 80/87 has the lowest lead content at a maximum of 0.5 grams lead = per U.S. gallon, and is only used in low compression ratio engines. Avgas 100/130 is a higher octane grade aviation gasoline, containing a = maximum of 4 grams of lead per US gallon, maximum 1.12 grams/litre. = 100LL "low lead" was designed to replace avgas 100/130. In the past other grades were also available, particularly for military = use, such as avgas 115/145 and 91/96. Note that the octanes of avgas = cannot be directly compared to those of mogas, as a different test = engine and method is used to determine the octane. The first (lower) = number is the lean mixture rating, the second (higher) number is the = rich mixture rating. For mogas, the octane rating is typically expressed = in the U.S. as an anti-knock index (known as "pump rating"), which is = the average of the octane rating based on the research and motor test = method ((R+M)/2). Fuel dyes aid pilots in identifying the proper fuel in their aircraft. = 80/87 is red, 100/130 is green, 115/145 is purple (leading to the U.S. = Naval aviation slang term "grape juice" for avgas) and 100LL is blue, = while jet fuel, JET A1, is clear or straw, being undyed. Untaxed diesel = fuel for off-road use is also dyed red. The annual U.S. usage of avgas was 236 million gallons (893 million = liters) in 2006. [2] [edit] Avgas compared to other fuels Many general aviation aircraft engines were designed to run on 80/87 = octane, roughly the standard for automobiles today. Direct conversions = to run on automotive fuel are fairly common and applied via the = supplemental type certificate (STC) process. However, the alloys used in = aviation engine construction are rather outdated, and engine wear in the = valves is a potential problem on automotive gasoline conversions. = Fortunately, significant history of mogas-converted engines has shown = that very few engine problems are actually caused by automotive = gasoline. A larger problem stems from the wider range of allowable vapor = pressures found in automotive gasoline; this can pose some risk to = aviation users if fuel system design considerations are not taken into = account. Automotive gasoline can vaporize in fuel lines causing a vapor = lock (a bubble in the line), starving the engine of fuel. This does not = constitute an insurmountable obstacle, but merely requires examination = of the fuel system, ensuring adequate shielding from high temperatures = and maintaining sufficient pressure in the fuel lines. This is the main = reason why both the specific engine model as well as the aircraft in = which it is installed must be supplementally certified for the = conversion. A good example of this is the Piper Cherokee with = high-compression 160 hp or 180 hp engines. Only later versions of the = airframe with different engine cowling and exhaust arrangements are = applicable for the automotive fuel STC, and even then require fuel = system modifications. Vapor lock typically occurs in fuel systems where a mechanically-driven = fuel pump mounted on the engine draws fuel from a tank mounted lower = than the pump. The reduced pressure in the line can cause the more = volatile components in automotive gasoline to flash into vapor, forming = bubbles in the fuel line and interrupting fuel flow. If an electric = boost pump is mounted in the fuel tank to push fuel toward the engine, = as is common practice in fuel-injected automobiles, the fuel pressure in = the lines is maintained above ambient pressure, preventing bubble = formation. Likewise, if the fuel tank is mounted above the engine and = fuel flows primarily due to gravity, as in a Cessna high-wing airplane, = vapor lock cannot occur, using either aviation or automotive fuels. In addition to vapor locking potential, automotive gasoline does not = have the same quality tracking as aviation gasoline. To help solve this = problem, an aviation fuel known as 82UL has recently been introduced. = This fuel is essentially automotive gasoline that has additional quality = tracking and restrictions on permissible additives. The main consumers of avgas at present (mid-2000s) are in North America, = Australia, Brazil, and Africa (mainly South Africa). In Europe, avgas prices are so high that there have been a number of = efforts to convert the industry to diesel instead, which is common, = inexpensive and has a number of advantages for aviation use. However, = avgas remains the most common fuel in Europe as well. [edit] Properties Avgas has a density of 6.02 lb/US gallon at 15 =B0C, or 0.72 kg/l, and = this density is commonly used for weight and balance computation. = Density increases to 6.40 lb/US gallon at -40 =B0C, and decreases by = about 0.5% per 5 =B0C increase in temperature.[3] __._,_.___=20 The Tailwind Forum group site is: = http://groups.yahoo.com/group/TailwindForum =20 Your email settings: Individual Email|Traditional=20 Change settings via the Web (Yahoo! ID required)=20 Change settings via email: Switch delivery to Daily Digest | Switch to = Fully Featured=20 Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe=20 __,_._,___ ------=_NextPart_000_0099_01C7EFBC.D135C2C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Here is a note on auto fuel in aviation = that=20 explains why the bubbles form in the clear fuel lines.  It is = mentioned in=20 the comparison of Avgas to other fuels.  Thought I would pass it=20 along.  JohnD
----- Original Message -----=20
From: Dave = & Theresa=20 Conrad
Sent: Monday, September 03, 2007 11:43 PM
Subject: [TailwindForum] often asked questions on = gas

I did a google search = "Lead in=20 gas" and came up with many hits. I read several but thought I'd post = this for=20 anyone interested to read. It lists lead contents of 80/87 100LL and=20 100/130. 

Dave=20 Conrad

Avgas is = a high-octane fuel used for aircraft and, in the past, racing cars. Avgas is a portmanteau for aviation gasoline, as=20 distinguished from mogas (motor = gasoline),=20 which is the everyday gasoline used in cars. Avgas is used in aircraft that use piston or Wankel engines; gas turbines can operate on avgas, but = typically do=20 not. Turbine and diesel engines are = designed to=20 use kerosene-based jet fuel.


[edit]

Avgas = properties and=20 varieties

Avgas has a = lower volatility=20 than mogas (i.e. it does not evaporate as quickly), which can be = important for=20 high-altitude use and higher temperatures. The particular mixtures in = use today=20 are the same as when they were first developed in the 1950s and 1960s, and therefore the high-octane ratings = are=20 achieved by the addition of tetra-ethyl lead = (TEL), a highly=20 toxic substance that was phased out for car use in most countries in the = 1980s. The main petroleum component used in blending avgas is = alkylate, which is essentially a mixture of = various isooctanes, and some = refineries=20 also use some reformate.

Avgas is = currently available=20 in several grades with differing maximum lead concentrations. Since TEL = is a=20 rather expensive additive, a minimum amount of it is typically added to = the fuel=20 to bring it up to the required octane rating so actual concentrations = are often=20 lower than the maximum.

Jet = fuel is not avgas. = It is similar=20 to kerosene and is used in turbine engines. In = Europe,=20 environmental and cost considerations have led to increasing numbers of = aircraft=20 being fitted with highly fuel-efficient diesel engines; these too run on = jet=20 fuel. Civilian aircraft use Jet-A, Jet-A1 or in severely cold climates = Jet-B.=20 There are other classification systems for military turbine and diesel = fuel. See=20 Jet fuel.


[edit]

Gasoline

Gasoline used for = aviation fuel=20 generally has two numbers associated with its octane rating. Examples of = this=20 include the (now almost completely unavailable) 80/87 avgas, and the = 100/130=20 avgas. The first number indicates the octane rating of the fuel tested = to=20 "aviation lean" standards, which is similar to the Motor Octane Number = (MON) rating=20 given to automotive gasoline. The second number indicates the octane = rating of=20 the fuel tested to the "aviation rich" standard, which tries to simulate = a=20 supercharged condition with a rich mixture, elevated temperatures, and a = high=20 manifold pressure.

100LL, spoken = as "100 low=20 lead", contains a lead based anti-knock compound but less than the = "highly-leaded"=20 100/130 avgas it effectively replaced. Most piston aircraft engines = require=20 100LL but it is scheduled to be phased out in the United States because of the lead toxicity. = An=20 alternative fuel has not yet been developed for these engines. While = there are=20 similar engines that burn non-leaded fuels aircraft are often purchased = with=20 engines that use 100LL because many airports only have 100LL. 100LL = contains a=20 maximum of 2 grams of lead per US = gallon, or=20 maximum 0.56 grams/litre and is the most commonly available and used = aviation=20 gasoline.

82UL is an = unleaded fuel=20 similar to automobile gasoline but without additives. It may be used in = aircraft=20 that have a Supplemental Type Certificate for the use of automobile = gasoline=20 with an aviation lean octane rating (MON) of 82 or less or an antiknock = index of=20 87 or less. It may not be used in engines that require 100LL. See Octane Rating. The FAA highly recommends = installing=20 placards stating the use of 82UL is or is not approved on those = airplanes that=20 specify unleaded autogas (mogas) as an = approved fuel[1].

Gasoline (MOGAS) may be = used in=20 aircraft that have a Supplemental Type = Certificate=20 for automotive gasoline. Most of these applicable aircraft have = low-compression=20 engines which were originally certified to run on 80/87 avgas and = require only=20 "regular" 87 <= FONT=20 style=3D"COLOR: #0029b9" color=3D#0029b9>anti-knock index = automotive=20 gasoline. Examples of this include the popular Cessna 172 or Piper Cherokee with the 150 hp variant of the = Lycoming O-320. Some aircraft engines were = originally=20 certified using a 91/96 avgas and have STC's available to run "premium" = 91 <= FONT=20 style=3D"COLOR: #0029b9" color=3D#0029b9>anti-knock index = automotive=20 gasoline. Examples of this include some Cherokee's with the 160 hp Lycoming O-320 or 180 hp O-360 or the Cessna 152 with the O-235.

Avgas 80/87 has = the lowest=20 lead content at a maximum of 0.5 grams lead per U.S. gallon, and is only used in low compression = ratio=20 engines.

Avgas 100/130 = is a higher=20 octane grade aviation gasoline, containing a maximum of 4 grams of lead = per US=20 gallon, maximum 1.12 grams/litre. 100LL "low = lead" was=20 designed to replace avgas 100/130.

In the past = other grades were=20 also available, particularly for military use, such as avgas 115/145 and = 91/96.=20 Note that the octanes of avgas cannot be directly compared to those of = mogas, as=20 a different test engine and method is used to determine the octane. The = first=20 (lower) number is the lean mixture rating, = the second=20 (higher) number is the rich mixture rating. = For mogas,=20 the octane rating is = typically=20 expressed in the U.S. as an <= FONT=20 style=3D"COLOR: #0029b9" color=3D#0029b9>anti-knock index = (known as "pump=20 rating"), which is the average of the octane rating based on the research and motor test method=20 ((R+M)/2).

Fuel=20 dyes aid=20 pilots in identifying the proper fuel in their aircraft. 80/87 is red, 100/130 is green, 115/145 is purple (leading to the U.S. = Naval=20 aviation slang term "grape juice" for avgas) and 100LL is blue, while jet fuel, JET A1, is clear or = straw, being=20 undyed. Untaxed diesel fuel for off-road use is also dyed red.

The annual U.S. = usage of=20 avgas was 236 million gallons (893 million liters) in 2006. [2]


[edit]

Avgas compared = to other=20 fuels

Many general aviation aircraft engines were designed to run on = 80/87 octane,=20 roughly the standard for automobiles today. Direct conversions to run on = automotive fuel are fairly common and applied via the supplemental type = certificate=20 (STC) process. However, the alloys used in aviation engine construction = are=20 rather outdated, and engine wear in the valves is a potential problem on = automotive gasoline conversions. Fortunately, significant history of=20 mogas-converted engines has shown that very few engine problems are = actually=20 caused by automotive gasoline. A larger problem stems from the wider = range of=20 allowable vapor pressures found in automotive gasoline; this can pose = some risk=20 to aviation users if fuel system design considerations are not taken = into=20 account. Automotive gasoline can vaporize in fuel lines causing a vapor = lock (a=20 bubble in the line), starving the engine of fuel. This does not = constitute an=20 insurmountable obstacle, but merely requires examination of the fuel = system,=20 ensuring adequate shielding from high temperatures and maintaining = sufficient=20 pressure in the fuel lines. This is the main reason why both the = specific engine=20 model as well as the aircraft in which it is installed must be = supplementally=20 certified for the conversion. A good example of this is the Piper = Cherokee with=20 high-compression 160 hp or 180 hp engines. Only later versions of the = airframe=20 with different engine cowling and exhaust arrangements are applicable = for the=20 automotive fuel STC, and even then require fuel system = modifications.

Vapor lock = typically occurs=20 in fuel systems where a mechanically-driven fuel pump mounted on the = engine=20 draws fuel from a tank mounted lower than the pump. The reduced pressure = in the=20 line can cause the more volatile components in automotive gasoline to = flash into=20 vapor, forming bubbles in the fuel line and interrupting fuel flow. If = an=20 electric boost pump is mounted in the fuel tank to push fuel toward the = engine,=20 as is common practice in fuel-injected automobiles, the fuel pressure in = the=20 lines is maintained above ambient pressure, preventing bubble formation. = Likewise, if the fuel tank is mounted above the engine and fuel flows = primarily=20 due to gravity, as in a Cessna high-wing airplane, vapor lock cannot = occur,=20 using either aviation or automotive fuels.

In addition to = vapor locking=20 potential, automotive gasoline does not have the same quality tracking = as=20 aviation gasoline. To help solve this problem, an aviation fuel known as = 82UL has recently = been=20 introduced. This fuel is essentially automotive gasoline that has = additional=20 quality tracking and restrictions on permissible additives.

The main = consumers of avgas=20 at present (mid-2000s) are in North America, Australia, Brazil, and Africa (mainly South Africa).

In Europe, avgas prices are so high that there = have been a=20 number of efforts to convert the industry to diesel instead, which is common, inexpensive = and has a=20 number of advantages for aviation use. However, avgas remains the most = common=20 fuel in Europe as well.


[edit]

Properties

Avgas has a density of 6.02 lb/US gallon at 15 =B0C, or 0.72 kg/l, and this density is = commonly used for=20 weight and balance = computation.=20 Density increases to 6.40 lb/US gallon at -40 =B0C, and decreases by = about 0.5%=20 per 5 =B0C increase in temperature.[3]

__._,_.___=20

The Tailwind Forum = group site=20 is: http://groups.yahoo.= com/group/TailwindForum




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