X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from web83909.mail.sp1.yahoo.com ([69.147.92.113] verified) by logan.com (CommuniGate Pro SMTP 5.3.7) with SMTP id 4340388 for flyrotary@lancaironline.net; Tue, 08 Jun 2010 13:26:58 -0400 Received-SPF: none receiver=logan.com; client-ip=69.147.92.113; envelope-from=keltro@att.net Received: (qmail 11281 invoked by uid 60001); 8 Jun 2010 17:26:24 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=att.net; s=s1024; t=1276017984; bh=ntowGgyurcG7+uUc9HYqSiV7lAaNKYrEdrNOYS4NH1M=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=Q3P3U7LTjYu3AYkQBY6Wcc2+Ot7WXVF1iif7TiwP89tg2+gqnVR6fcmGQXn+2ERTFq3pjBp77vJW1mvwGeB9Gln+LxrdIwke70Mub1wLz3TmjO9RrCyFM+CF1gUBfLwge9B2G6chs1nS1dix0WRi32CHcL7umS+lz6jcvPu5xYs= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=att.net; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=n2ONOTUaX6+BeOnXDkldCWNnovnFLwJh64saJVd+D7mEf24GiTh/mNwMaV6d25P0ZBuNlqJFQEwzOjvuDeo9DXvt0Wr02VHsKy0XHzqmEep9W8hsfeGm2gBX8B88lLbiyOCV/0Koru15bPMY1ZwnYQub4GbAOriwYbSn+hjyhbw=; Message-ID: <114060.11147.qm@web83909.mail.sp1.yahoo.com> X-YMail-OSG: wY.whlAVM1lhQ1oWU36rypU9ufCTlKAj8WTDtSixiQgEvba TTMQ1rFWzA7i1oCu0kJM3YgtNMrCjGizNy3Z.IFwPnrL1OkhtRwm3IDQVmUU vNVgJ8vPHF4bPBrrRq7jIxl8YYhFWsPH0I_Xpr8cR4yOqcNmRJnFVCgqaR9A M16JNfN8RKLLuizf8sWJz0mDgRVDQ5VZLl.LujHOFzl5rmJbO1eZwLmP1BsY 1nAQos8ek04GdGyKxndRF.ey5bvUXLnrAIvaEXaTWf.k_1rZtXv6Due38gW5 kGQl1QfO7TlkERXn5rFjJu3TuHClzFfdZU6sSpjFH5mEtQp2FRwfqXXXZSTT RsqS5v3rDvrk- Received: from [208.114.45.107] by web83909.mail.sp1.yahoo.com via HTTP; Tue, 08 Jun 2010 10:26:23 PDT X-Mailer: YahooMailRC/397.8 YahooMailWebService/0.8.103.269680 References: Date: Tue, 8 Jun 2010 10:26:23 -0700 (PDT) From: Kelly Troyer Subject: Re: [FlyRotary] Re: high/low pressure pumps question To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-665955071-1276017983=:11147" --0-665955071-1276017983=:11147 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Guys,=0A=A0 Very enlightening and=A0truly food for thought to those of us s= till in the construction stage...........I have just=0Aone more question to= ask............Previous info seemed to indicate that return fuel should be= entering the=0Afuel tank at the bottom or at least close to the bottom....= .........In light of Steve's observations would it =0Aseem reasonable that = air bubbles=A0in the return fuel would be eliminated to the tank vent faste= r if the return=0Aline was at the top or close to the top of the tank ??...= .............=A0=A0=0A=A0Kelly Troyer=0A"Dyke Delta"_13B ROTARY Engine=0A"R= WS"_RD1C/EC2/EM2=0A"Mistral"_Backplate/Oil Manifold =0A=0A=0A=0A=0A________= ________________________=0AFrom: Steven W. Boese =0ATo: Ro= tary motors in aircraft =0ASent: Tue, June 8, = 2010 11:29:55 AM=0ASubject: [FlyRotary] Re: high/low pressure pumps questio= n=0A=0A=0A=0A=0AIn the reference provided by Ed, there is mention of the fu= el temperature being monitored to allow compensation for changes in fuel vi= scosity with changes in temperature.=A0 The ECU=A0might be changing injecto= r pulse width in response to the fuel temperature rather than changing the = fuel pressure in an attempt to avoid vapor lock.=0A=A0=0AWhen I first assem= bled my fuel system, I put a section of glass tubing in the return line aft= er the pressure regulator.=A0 I did this because I saw bubbles in the fuel = being returned to the tank and assumed that there was an air leak somewhere= in the system, most likely in the suction section between the tank and the= pumps.=A0 I never found an air leak after many hours of searching.=A0 The = bubbles I saw were air bubbles that separated from the fuel during the rapi= d pressure drop through the regulator.=A0 The formation of the air bubbles = takes place quickly whereas the dissolution back into the fuel is much slow= er.=A0 The solubility of air in fuel is much greater than the solubility of= air in water, and we all have seen the air bubbles=A0that form on the wall= s=A0a container of water as it warms up and the solubility decreases.=A0 Wh= en returning the fuel to the tank, eventually the air would be purged from = the liquid fuel and out the vent.=A0 I observed the elimination of the air bubbles in the return line after about 10 minutes o= f recurculation when using a vented fuel tank of only a gallon in volume.= =A0 I don't know how long this would take in the case of a large wing tank.= =0A=A0=0AReturning the fuel from the regulator to the supply line orto a sm= all header tank feeding the fuel pumps seems to me to have the potential fo= r problems in at least three ways:=A01)=A0 from increasing fuel vapor press= ure as temperature rises,=A0 2) =A0decreased solubility of air in the fuel = as temperature rises,=A0 3)=A0 the accumulation of air as a result of the f= ormation of air bubbles in the pressure regulator which occurs even without= an increase in temperature.=A0 All of these things could contribute to vap= or lock.=A0 =0A=A0=0AThese are just my observations.=A0 There is also the i= ndisputable observation of the success of Ed's system for many years of ope= ration.=0A=A0=0ASteve Boese =0ARV6A, 1986 13B NA, RD1A, EC2=0A=A0=0A=0A____= ____________________________=0AFrom: Rotary motors in aircraft [flyrotary@l= ancaironline.net] On Behalf Of Al Wick [alwick@juno.com]=0ASent: Tuesday, J= une 08, 2010 8:59 AM=0ATo: Rotary motors in aircraft=0ASubject: [FlyRotary]= Re: high/low pressure pumps question=0A=0A=0AHi Ed. You often make signifi= cant contributions that help improve flight safety. If you share your fuel = design, at least do the calculations and let users know how close this is t= o vapor lock. We're talking about life risk here. You are glossing over my = point and changing the topic. Returning fuel to pump inlet is very risky an= d should not be done unless you desire to operate on the threshold of vapor= lock.=0A=A0=0AI agree, there is one exception. That's if you have=A0one of= the new fuel pump controllers that measures fuel parameters and alters pum= p speed. I looked into that one years ago. Talk about added complexity!=0A= =A0=0AOn with the good stuff!=0A=A0=0A-al wick --0-665955071-1276017983=:11147 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
=0A
Guys,
=0A
  Very enlighten= ing and truly food for thought to those of us still in the constructio= n stage...........I have just
=0A
one more question to ask........= ....Previous info seemed to indicate that return fuel should be entering th= e
=0A
fuel tank at the bottom or at least close to the bottom.....= ........In light of Steve's observations would it
=0A
seem reason= able that air bubbles in the return fuel would be eliminated to the ta= nk vent faster if the return
=0A
line was at the top or close to t= he top of the tank ??................  
 
Kelly Troy= er
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Bac= kplate/Oil Manifold =0A

=0A

=0A
=0A
=0AFrom: Steven W. Boese <SBoese@uwyo.edu>
To: Rotary motors in aircraft <flyro= tary@lancaironline.net>
Sent: Tue, June 8, 2010 11:29:55 AM
Subject: [FlyRotary] Re: high/low pressure pumps question
=0A=0A=0A=0A=0A=0A=0A
=0A
=0A
 
=0A
In the refer= ence provided by Ed, there is mention of the fuel temperature being monitor= ed to allow compensation for changes in fuel viscosity with changes in temp= erature.  The ECU might be changing inj= ector pulse width in response to the fuel temperature rather than changing = the fuel pressure in an attempt to avoid vapor lock.
=0A
 
=0A
When I first assembled my fuel system, I put a section of glass tubing in = the return line after the pressure regulator.  I did this because I sa= w bubbles in the fuel being returned to the tank and assumed that there was= an air leak somewhere in the system, most likely in the suction section be= tween the tank and the pumps.  I never found an air leak after many ho= urs of searching.  The bubbles I saw were air bubbles that separated f= rom the fuel during the rapid pressure drop through the regulator.  Th= e formation of the air bubbles takes place quickly whereas the dissolution = back into the fuel is much slower.  The solubility of air in fuel is m= uch greater than the solubility of air in water, and we all have seen the a= ir bubbles that form on the walls a container of water as it warm= s up and the solubility decreases.  When returning the fuel to the tan= k, eventually the air would be purged from the liquid fuel and out the vent.  I observed the elimination of= the air bubbles in the return line after about 10 minutes of recurculation= when using a vented fuel tank of only a gallon in volume.  I don't kn= ow how long this would take in the case of a large wing tank.
= =0A
 
=0A
Returning the fuel from the regulato= r to the supply line orto a small header tank feeding the fuel pumps seems = to me to have the potential for problems in at least three ways: 1)&nb= sp; from increasing fuel vapor pressure as temperature rises,  2) &nbs= p;decreased solubility of air in the fuel as temperature rises,  3)&nb= sp; the accumulation of air as a result of the formation of air bubbles in = the pressure regulator which occurs even without an increase in temperature= .  All of these things could contribute to vapor lock. 
=0A
=  
=0A
These are just my observations.  There is also the indisputabl= e observation of the success of Ed's system for many years of operation.
=0A
 
=0A
<= FONT size=3D2 face=3Dtahoma>Steve Boese= =0A
RV6A, 1986 13B NA, RD1A, EC2
=0A
 
=0A
= =0A
=0AFro= m: Rotary motors in aircraft [flyrotary@lancaironline.net] On Behalf Of= Al Wick [alwick@juno.com]
Sent: Tuesday, June 08, 2010 8:59 AMTo: Rotary motors in aircraft
Subject: [FlyRotary] Re: h= igh/low pressure pumps question

=0A
=0A
= =0A
Hi Ed. You often make significant contr= ibutions that help improve flight safety. If you share your fuel design, at= least do the calculations and let users know how close this is to vapor lo= ck. We're talking about life risk here. You are glossing over my point and = changing the topic. Returning fuel to pump inlet is very risky and should n= ot be done unless you desire to operate on the threshold of vapor lock.
=0A
 
=0A
I agree, there is one exception. That's if you hav= e one of the new fuel pump controllers that measures fuel parameters a= nd alters pump speed. I looked into that one years ago. Talk about added co= mplexity!
=0A
 =0A
On with the good stuff!
= =0A
 
=0A
-al wick
--0-665955071-1276017983=:11147--