X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 26 Nov 2008 19:01:38 -0500 Message-ID: X-Original-Return-Path: Received: from web33905.mail.mud.yahoo.com ([209.191.69.183] verified) by logan.com (CommuniGate Pro SMTP 5.2.10) with SMTP id 3317251 for lml@lancaironline.net; Tue, 25 Nov 2008 16:52:20 -0500 Received: (qmail 72603 invoked by uid 60001); 25 Nov 2008 21:52:20 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type:Message-ID; b=5VChCkI52svUd4vxspUOIP1PL7jKZdI84VuiliYd8EQDNHy732Gfj0D7r/9Srug+/wJGAMFasRgETIg4E3sYQg/bcObCGbbu0o7jhikXAS26X5pO+u4s2r+RPEp3qoJninKCYbQKAqy4lPWMNjthl1vVsBpJuE7joB4eASFTUdE=; X-YMail-OSG: zNREvboVM1mHFiDRKmeBRLLprIchSWna3TY0ZhzgQAD8QLM2iAihXfY6w1juh02.t49K6E5DuRxTxR9umKuPX_QM9bVXPUZSnAxRt3FC1.CTqoW.oSfUD_h3NN27MzXGiEyBqEpWbzLSHllnXdWGptMgb0OdupQi2sv6Q67b1H_Pvg-- Received: from [71.208.9.115] by web33905.mail.mud.yahoo.com via HTTP; Tue, 25 Nov 2008 13:52:20 PST X-Mailer: YahooMailWebService/0.7.260.1 X-Original-Date: Tue, 25 Nov 2008 13:52:20 -0800 (PST) From: Bill Hannahan Reply-To: wfhannahan@yahoo.com Subject: Re: [LML] Re: 360 Fuel Vent X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1424244106-1227649940=:72560" X-Original-Message-ID: <333572.72560.qm@web33905.mail.mud.yahoo.com> --0-1424244106-1227649940=:72560 Content-Type: text/plain; charset=iso-8859-7 Content-Transfer-Encoding: quoted-printable =A0 Interesting question Eric. I don=A2t know the answer, and need to leave soon, but here are some thoughts. =A0 At 18,000 ft half the atmosphere is below you, the absolute pressure is about 7.5 psi. Neglecting ram air pressure th= e pressure inside the tank is 7.5 psi. =A0 Now imagine we lower the wing instantly to sea level. The pressure outside the wing is about 15 psi and the tank differential is 7.5 psi, (1,080 lb/sq ft). The wing will be crushed. =A0 My 360 wing holds 23 gal, 5,313 cu in. Assuming the fuel tank is empty and does not crush, we have to add 2,637 cu in of se= a level air to equalize the tank. =A0 Using Grayhawk=A2s ID of 0.156, the area of the tube is 0.019 sq in. Assuming an average velocity of 20 ft / sec the fl= ow rate will be 4.6 cu in / sec and time to equalize will be 9.6 min. =A0 Comments. =A0 I don=A2t know what differential gives 20 ft/sec, it depends on tube length, fittings, bends, burs, dirt, bugs etc. M= aybe Grayhawk's calculator can give a ballpark number. =A0 Air at altitude is less dense so more cubic inches are required. =A0 LIV tanks are larger, so proportionally more air and time required. =A0 The critical cases would be emergency descent with empty tank, and extreme climb rate possible with turbine engin= es and minimum fuel. =A0 Bill Hannahan =20 wfhannahan@yahoo.com --- On Tue, 11/25/08, Sky2high@aol.com wrote: From: Sky2high@aol.com Subject: [LML] Re: 360 Fuel Vent To: lml@lancaironline.net Date: Tuesday, November 25, 2008, 6:00 AM =20 Eric, =A0 Assuming all kinds of things and using pipe flow calculator for a gas known= =20 as air: If your engine is using 15 gal/hr =3D 2 cu ft/hr =3D .0335 cfm Suppose the inside diameter of 1/4" tubing is .156", the pressure of the=20 air at the vent is .7 psi (about 200 kts) and the temp is 31F, then the air= is=20 traveling in the tube at 3 Kts. =A0 "So What?" You might ask.=A0=20 =A0 OK then, take a gallon jug, fit a 3/8 inch tube (engine pump=A0fuel line=20 size?)=A0at one end and a quarter inch tube at the other end=A0(vent=20 line).=A0 Use a good sealing=A0putty.=A0 Fill the jug with water.=A0=20 Let the water drain out the 3/8 tube and time it.=A0 If it drains in=A03=20 minutes or less (1 gal/4 min =3D 15 gals/hr., 1 gal/3 min =3D 20 gph), the = vent is=20 large enough.=A0 That's just using gravity -=A0without assistance=20 from=A0the engine pump or the vent pressure and 100LL may be less=20 viscous. =A0 Grayhawk =A0 PS=A0Let us in on the results.=A0 =A0 In a message dated 11/24/2008 10:01:34 P.M. Central Standard Time,=20 cassutt@windstream.net writes: I am not=20 using the header tank in my 360 and have installed 1/4" od tubing as the = vent=20 for each wing tank. My old SB manual says nothing about fuel vent size ev= en=20 with the header and what published updates there are for the extended bay= =20 don't have a size listed either.=A0 Is this big enough dia. for pulling= =20 fuel straight from the wings or should it be larger? What have others=20 done. Eric Demaray 360 SB -- For archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html One site has it all. Your email accounts, your social networks, and the thi= ngs you love. Try the new AOL.com today!=0A=0A=0A --0-1424244106-1227649940=:72560 Content-Type: text/html; charset=iso-8859-7 Content-Transfer-Encoding: quoted-printable

 

Interesting question Eric. I = don=A2t know the answer, and need to leave soon, but here are some thoughts.<= /span>

 

At 18,000 ft half the atmosph= ere is below you, the absolute pressure is about 7.5 psi. Neglecting ram air pressure th= e pressure inside the tank is 7.5 psi.

 

Now imagine we lower the wing= instantly to sea level. The pressure outside the wing is about 15 psi and the tank differential is 7.5 psi, (1,080 lb/sq ft). The wing will be crushed.

 

My 360 wing holds 23 gal, 5,3= 13 cu in. Assuming the fuel tank is empty and does not crush, we have to add 2,637 cu in of se= a level air to equalize the tank.

 

Using Grayhawk=A2s ID of 0.15= 6, the area of the tube is 0.019 sq in. Assuming an average velocity of 20 ft / sec the fl= ow rate will be 4.6 cu in / sec and time to equalize will be 9.6 min.

 

Comments.

 

I don=A2t know what different= ial gives 20 ft/sec, it depends on tube length, fittings, bends, burs, dirt, bugs etc. M= aybe Grayhawk's calculator can give a ballpark number.

 

Air at altitude is less dense= so more cubic inches are required.

 

LIV tanks are larger, so prop= ortionally more air and time required.

 

The critical cases would be e= mergency descent with empty tank, and extreme climb rate possible with turbine engin= es and minimum fuel.

 

Bill Hannahan


= --- On Tue, 11/25/08, Sky2high@aol.com <Sky2high@aol.com> wrote:
From: Sky2high@aol.com <Sky2high@a= ol.com>
Subject: [LML] Re: 360 Fuel Vent
To: lml@lancaironline.net=
Date: Tuesday, November 25, 2008, 6:00 AM

=20
Eric,
 
Assuming all kinds of things and using pipe flow calculator for a gas = known=20 as air:
If your engine is using 15 gal/hr =3D 2 cu ft/hr =3D .0335 cfm
Suppose the inside diameter of 1/4" tubing is .156", the pressure of t= he=20 air at the vent is .7 psi (about 200 kts) and the temp is 31F, then the air= is=20 traveling in the tube at 3 Kts.
 
"So What?" You might ask. 
 
OK then, take a gallon jug, fit a 3/8 inch tube (engine pump fuel= line=20 size?) at one end and a quarter inch tube at the other end (vent= =20 line).  Use a good sealing putty.  Fill the jug with water.&= nbsp;=20 Let the water drain out the 3/8 tube and time it.  If it drains in&nbs= p;3=20 minutes or less (1 gal/4 min =3D 15 gals/hr., 1 gal/3 min =3D 20 gph), the = vent is=20 large enough.  That's just using gravity - without assistance=20 from the engine pump or the vent pressure and 100LL may be less=20 viscous.
 
Grayhawk
 
PS Let us in on the results. 
 
In a message dated 11/24/2008 10:01:34 P.M. Central Standard Time,=20 cassutt@windstream.net writes:
I am not=20 using the header tank in my 360 and have installed 1/4" od tubing as the = vent=20 for each wing tank. My old SB manual says nothing about fuel vent size ev= en=20 with the header and what published updates there are for the extended bay= =20 don't have a size listed either.  Is this big enough dia. for pullin= g=20 fuel straight from the wings or should it be larger? What have others=20 done.

Eric Demaray
360 SB

--
For archives and unsub= =20 http://mail.lancaironline.net:81/lists/lml/List.html



One site has it all.= Your email accounts, your social networks, and the things you love. Try= the new AOL.co= m today!

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