X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from outbound-mail.vgs.untd.com ([64.136.55.15] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with SMTP id 5095284 for flyrotary@lancaironline.net; Wed, 17 Aug 2011 13:41:53 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.55.15; envelope-from=alwick@juno.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=juno.com; s=alpha; t=1313602878; bh=47DEQpj8HBSa+/TImW+5JCeuQeRkm5NMpJWZG3hSuFU=; l=0; h=Message-ID:From:To:Subject:Date:Content-Type; b=gyjOQHsQRWD2pnFyKIE2VhbATNA9TeKUMfDhZ5ITQ/uUKZd0JkU7HtZj9+UTswIPN x+II4W++3WGxDhawg0XBICTznN8XkHqMGxNxspiUVmsCTDVrG8a8Nt3tn6X06uN47O YS+kCozUpSVU0SV4OpVPkCXiNM+QtxbfVs4/qFGA= Received: from Penny (50-39-174-23.bvtn.or.frontiernet.net [50.39.174.23]) by smtpout01.vgs.untd.com with SMTP id AABHEZ9J4AWWUAAS for (sender ); Wed, 17 Aug 2011 10:40:42 -0700 (PDT) Message-ID: <0991F27999474C988BC0BA43A038A1FC@Penny> From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] In-tank pumps Date: Wed, 17 Aug 2011 10:40:40 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01A9_01CC5CCA.1BA1A7B0" 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 X-UNTD-BodySize: 8542 X-ContentStamp: 20:10:4161977088 X-MAIL-INFO:1614149499d0f434d5c47d94847db98191b01d7de1208d9599e11db0e119e1a4509009b5147094a1942499a5b9d9c5a534d0fd9061698169814d2181114db1114df57d74d9e9a9512904e9747105710c312975714d9170a470a4141da49914509914d075302d11a9d020b18d1140353d3939c1897995647031a4e4b07099d1d190b0dd8434d5441d449d658d20f9d4d1f464c465e455c480b44490ad25106429bda5f955c9a07174c0f010f02da4d980156029bd21616169040c7124b149a9 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkL/wVYqG1YawrVz8t8+oPHD/PtxrS7pCIg== X-UNTD-Peer-Info: 10.181.42.31|smtpout01.vgs.untd.com|smtpout01.vgs.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_01A9_01CC5CCA.1BA1A7B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable What's the best fuel design to prevent vapor lock? Copy any auto mfg = > method. They all use the same method because it's SOOO effective. = OEM=20 > fuel designs minimize every REAL risk we have in our aircraft. They = use=20 > self cleaning filters that have around 10 or 20 times more surface = area=20 > than stupid in line filters. They minimize pressure drop at pump = inlet=20 > by using large coarse filters there. Submerged pumps. Every car mfg = uses=20 > the same system. Do you know how rare that is? They do it because = the=20 > wet design with self cleaning filters eliminates all historical = failures. > I recently converted my sys to automotive style. Details at bottom = of page: > = http://www.maddyhome.com/canardpages/pages/alwick/index_files/Page467.htm= > =20 Can you explain something to me on this point? Considering that the = in-tank pump has a positive volume, how does it=20 avoid a negative pressure when the fuel level gets near the bottom of = the tank? I ask, because most airplanes tend to=20 have very flat tanks, and fuel often gets left on the ground for = weight and balance reasons. Pulling that last few=20 gallons off the bottom of the tank can be VERY important. Putting the = pump in the tank is going to result in pulling=20 fuel uphill at some point unless you have a flat pump. I'm going to go out on a limb and say you're wrong. Manufacturers all = use the in-tank system because it simplifies=20 design and assembly. They all use pre-assmebled console "clusters", = and many other pre-assembled components for the=20 same reason. It is not rare at all. In-tank pumps are not a safety = issue. It's an economic one. The best design for avoiding vapor lock is going to be the one that = puts the most pressure ahead of the pumps. Whether=20 this is done by putting the fuel as high above the pumps as possible, = pressurizing the tank, or magical pixie dust,=20 positive pressure at the pump inlet is the only answer. The in-tank = pump only marginally solves the problem and is a=20 maintenance nightmare. But, to each his/her own. You build it. You fly it. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_01A9_01CC5CCA.1BA1A7B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
<how does it
<avoid a negative pressure when the fuel = level gets=20 near the bottom of the tank?
 
It doesn't. Actually, GM takes = advantage of that=20 and designs inlet so that you'll run out of fuel at home instead of on = the road.=20 Pretty interesting.
 
I mention the oem design because I'd = like to save a=20 few lives. Fewer crashes. I hope a few guys will be open minded. Test = their=20 ideas instead of speculate. Compare results to OEM method.
 
If we broke down fuel design into = individual=20 components. Like self priming, pressure drop at inlet, effect of = contaminants,=20 etc. Then did the simple tests to prove which is superior, it would be=20 enlightening.
 
-al wick
----- Original Message -----
From:=20 Ernest=20 Christley
Sent: Wednesday, August 17, = 2011 8:40=20 AM
Subject: [FlyRotary] In-tank = pumps

Al Wick wrote:

> What's the best fuel design = to=20 prevent vapor lock? Copy any auto mfg
> method. They all use = the same=20 method because it's SOOO effective. OEM
> fuel designs minimize = every=20 REAL risk we have in our aircraft. They use
> self cleaning = filters=20 that have around 10 or 20 times more surface area
> than stupid = in line=20 filters. They minimize pressure drop at pump inlet
> by using = large=20 coarse filters there. Submerged pumps. Every car mfg uses
> the = same=20 system. Do you know how rare that is? They do it because the
> = wet=20 design with self cleaning filters eliminates all historical = failures.
>=20 I recently converted my sys to automotive style. Details at bottom of=20 page:
> http://www.maddyhome.com/canardpages/pages/alwick/index_files/P= age467.htm
> =20

Can you explain something to me on this point?  = Considering that=20 the in-tank pump has a positive volume, how does it
avoid a = negative=20 pressure when the fuel level gets near the bottom of the tank?  I = ask,=20 because most airplanes tend to
have very flat tanks, and fuel = often gets=20 left on the ground for weight and balance reasons.  Pulling that = last few=20
gallons off the bottom of the tank can be VERY important.  = Putting=20 the pump in the tank is going to result in pulling
fuel uphill at = some=20 point unless you have a flat pump.

I'm going to go out on a = limb and=20 say you're wrong.  Manufacturers all use the in-tank system = because it=20 simplifies
design and assembly.  They all use pre-assmebled = console=20 "clusters", and many other pre-assembled components for the
same=20 reason.  It is not rare at all.  In-tank pumps are not a = safety=20 issue.  It's an economic one.

The best design for avoiding = vapor=20 lock is going to be the one that puts the most pressure ahead of the=20 pumps.  Whether
this is done by putting the fuel as high = above the=20 pumps as possible, pressurizing the tank, or magical pixie dust, =
positive=20 pressure at the pump inlet is the only answer.  The in-tank pump = only=20 marginally solves the problem and is a
maintenance = nightmare.

But,=20 to each his/her own.  You build it.  You fly=20 it.

--
Homepage:  http://www.flyrotary.com/
Archi= ve and=20 UnSub:   http:= //mail.lancaironline.net:81/lists/flyrotary/List.html
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