REFLECTOR: Fuel Vent (used to be Odd Fuel Stain)
Brooke Wolf
bwolf1 at tds.net
Mon Nov 21 14:40:07 CST 2011
I think they are talking about something like the attached photo. The vent line goes up the firewall, then comes forward along the roof line inside the overhead plenum for about 4 feet. Then it loops back to the firewall, then down and out the airplane.
Brooke
> From: "Alex Balic" <velocity_pilot at verizon.net>
> Date: November 21, 2011 3:07:50 PM EST
> To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Odd fuel stain?
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>
>
> No- extend the loop on the vent system (which should currently go up the
> firewall to the top of the roof, then back down through the belly )foreword
> along the roof of the aircraft so when the aircraft is pitched up at say 45
> degrees, the foreword most part of the loop will be at a higher elevation
> than the front of the strakes where the fuel is located
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Robert Wood
> Sent: Monday, November 21, 2011 1:36 PM
> To: bobj at jaxtechllc.com; Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Odd fuel stain?
>
> I think when saying extend the vent forward they are saying during the
> building process inside the tank. Am I wrong?
>
> Bob Wood
>
> On Nov 21, 2011, at 1:32 PM, "Bob Jackson \(Jax Tech\)"
> <bobj at jaxtechllc.com> wrote:
>
>> John,
>>
>> Can you translate your 500 fpm climb limit to a number of degrees nose up?
>
>>
>> Our normal full fuel, 160 KIAS climb to altitude (turbo IO-550N) is with
>> 1000 fpm and 7 degrees nose up. We occasionally get a 'whiff' of fuel in
>> the cockpit after takeoff or touch-n-goes, but I normally do those with a
>> ~18 degrees nose up attitude (100 KIAS). I assumed these were caused by
>> occasional fuel sloshing, not by a steady state venting problem!
>>
>> Are you saying we need to either start climbing out at higher than 160
> KIAS,
>> or a lower power setting, or extend our vent line a couple of feet along
> the
>> top of the fuselage?
>>
>> When this topic came up a while back, and I did rough calculations back
> then
>> I figured that in climbouts the fuel was going to be very close to the top
>> of our vent loop (which is as close to the top of the fuselage as we could
>> make it), but not over.
>>
>> I don't have the exact measurements here -- but the way I roughly figure
> it
>> is: the top of the vent loop extends ~18" above the spar beam, and the
>> tanks are full and there is fuel at the front of the strake (and the
> strake
>> front is about 48" forward of the vent line), and that it would take a
> climb
>> angle greater than ~ 20 degrees (arctan[18/48])before you started venting.
>> I'll have to take some more accurate measurements.
>>
>> Bob Jackson
>> Turbo IO-550N XL/RG
>>
>>
>> -----Original Message-----
>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>> Behalf Of John Abraham
>> Sent: Monday, November 21, 2011 8:57 AM
>> To: 'Velocity Aircraft Owners and Builders list'
>> Subject: Re: REFLECTOR: Odd fuel stain?
>>
>> General rule of thumb I use is no more than 500fpm climb when above 75%
>> tanks. This helps prevent dumping fuel out your vent which you cannot
>> calculate very easily. The only solution to this would be to run your
> vent
>> 1-2 feet forward so that your strake angle does not exceed the top of the
>> vent.
>>
>> IO-540 (260HP) RG should be climbing between 120-130kias, 300HP Lycoming's
>> and Continentals should be 130-145KIAS. *Note that the IO-550 RG's at 135
>> will be above 500FPM so you may have to climb at a faster speed than 140.
>> Turbo charged aircraft with RG systems are between 145-165KIAS in a climb.
>
>>
>> FG aircraft, speeds in climb will vary about 10kts less.
>>
>> Also, make sure your vent is scarfed into the wind so that you continually
>> pressurize your tanks and don't create a vacuum. Vent lines in the back
>> should be treated the same as your main feed lines. You want a continual
>> downhill slope into the tanks so that you don't have any low point in the
>> vent lines otherwise you may get some fuel stuck in the vent that cant
>> pressurize itself out very easily which will lead to uneven feeding.
>>
>> John
>>
>> -----Original Message-----
>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>> Behalf Of Scott Baker
>> Sent: Monday, November 21, 2011 7:47 AM
>> To: Velocity Aircraft Owners and Builders list
>> Subject: Re: REFLECTOR: Odd fuel stain?
>>
>> Maybe not the negative-G, but very likely the steep pitch up maneuver. I
>> have many times seen (from the ground) a vapor trail of fuel exiting the
>> vent tube from Velocity aircraft doing high performance takeoffs at
>> Sebastian.
>> Scott B.
>>
>> ----- Original Message -----
>> From: "Scott Derrick" <scott at tnstaafl.net>
>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> Sent: Sunday, November 20, 2011 7:18 PM
>> Subject: REFLECTOR: Odd fuel stain?
>>
>>
>>> So after design/install of a new forward cabin heater system I took the
>>> bird for a test flight. I as also testing a new oil temperature sensor
>>> which is working fabulously!
>>>
>>> Played around to the north of GNT getting the plane setup for LOP at 9500
>
>>> and playing with different settings of the heater controls, there is a
>>> separate control for pilot and co-pilot positions, plus the oil flap
>>> provides full or reduced air flow.
>>>
>>> The problem occurred when I did a walk around in front of the hanger
> after
>>
>>> the flight and saw a bit of a fuel(blue) stain on the rear cowl! Thats
>>> really odd I thought! It started about a foot to the rear of the fuel
>>> vent and was kinda wispy looking, about a foot+ long.
>>>
>>> I was pretty upset as I don't like fuel leaks, who does, and we are
>>> planning on flying to Tahoe Tuesday morning. I was contemplating where it
>
>>> could have come from, There is no way it cam from the engine compartment,
>
>>> it would have pooled at the low point in the bottom cowl and come out the
>
>>> drain holes, and this was nowhere near that. Plus the fact, is was
>>> directly in line with the fuel vent, but why would it spit fuel in
> flight!
>>>
>>> Then I had an idea.
>>>
>>> When I came back to the pattern the airport crowd requested a low pass,
>>> you know an altimeter/compass check, so I sucked the gear back up and did
>
>>> a 185 knot 100 ft pass down the runway. Turning about 2600 RPM, at mid
>>> field I pulled up into a steeper than usual climb, about 4,000+ ft per
>>> minute, the speed rapidly unwinding, the altimeter doing the reverse. At
>>> the top, about 1,000 agl and now at 120 knots I pushed over a little more
>
>>> aggressive than I usually do, going just a bit negative G for 5 seconds
> or
>>
>>> so, leveled off and made a sedate pattern to landing.
>>>
>>> My fuel tanks are almost full, about 26 gallons in 30 gallons tanks.
>>>
>>> Now I wonder did the negative G maneuver cause the fuel to spit out the
>>> vent? Anybody else experience a similar thing?
>>>
>>> Scott
>>>
>>> --
>>> We are all here for a spell; get all the good laughs you can.
>>> Will Rogers
>>> _______________________________________________
>>> To change your email address, visit
>>> http://www.tvbf.org/mailman/listinfo/reflector
>>>
>>> Visit the gallery! www.tvbf.org/gallery
>>> user:pw = tvbf:jamaicangoose
>>> Check new archives: www.tvbf.org/pipermail
>>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>>
>> _______________________________________________
>> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery! www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> _______________________________________________
> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
>
>
>
> From: Robert Wood <slvegl99 at aol.com>
> Date: November 21, 2011 3:12:05 PM EST
> To: reflector at tvbf.org
> Subject: Re: REFLECTOR: Odd fuel stain?
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>
>
> Ohh, OK. Mine is fine then.
> Bob Wood
>
>
> -----Original Message-----
> From: Alex Balic <velocity_pilot at verizon.net>
> To: 'Velocity Aircraft Owners and Builders list' <reflector at tvbf.org>
> Sent: Mon, Nov 21, 2011 3:08 pm
> Subject: Re: REFLECTOR: Odd fuel stain?
>
> No- extend the loop on the vent system (which should currently go up the
> firewall to the top of the roof, then back down through the belly )foreword
> along the roof of the aircraft so when the aircraft is pitched up at say 45
> degrees, the foreword most part of the loop will be at a higher elevation
> than the front of the strakes where the fuel is located
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Robert Wood
> Sent: Monday, November 21, 2011 1:36 PM
> To: bobj at jaxtechllc.com; Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Odd fuel stain?
>
> I think when saying extend the vent forward they are saying during the
> building process inside the tank. Am I wrong?
>
> Bob Wood
>
> On Nov 21, 2011, at 1:32 PM, "Bob Jackson \(Jax Tech\)"
> <bobj at jaxtechllc.com> wrote:
>
> > John,
> >
> > Can you translate your 500 fpm climb limit to a number of degrees nose up?
>
> >
> > Our normal full fuel, 160 KIAS climb to altitude (turbo IO-550N) is with
> > 1000 fpm and 7 degrees nose up. We occasionally get a 'whiff' of fuel in
> > the cockpit after takeoff or touch-n-goes, but I normally do those with a
> > ~18 degrees nose up attitude (100 KIAS). I assumed these were caused by
> > occasional fuel sloshing, not by a steady state venting problem!
> >
> > Are you saying we need to either start climbing out at higher than 160
> KIAS,
> > or a lower power setting, or extend our vent line a couple of feet along
> the
> > top of the fuselage?
> >
> > When this topic came up a while back, and I did rough calculations back
> then
> > I figured that in climbouts the fuel was going to be very close to the top
> > of our vent loop (which is as close to the top of the fuselage as we could
> > make it), but not over.
> >
> > I don't have the exact measurements here -- but the way I roughly figure
> it
> > is: the top of the vent loop extends ~18" above the spar beam, and the
> > tanks are full and there is fuel at the front of the strake (and the
> strake
> > front is about 48" forward of the vent line), and that it would take a
> climb
> > angle greater than ~ 20 degrees (arctan[18/48])before you started venting.
> > I'll have to take some more accurate measurements.
> >
> > Bob Jackson
> > Turbo IO-550N XL/RG
> >
> >
> > -----Original Message-----
> > From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> > Behalf Of John Abraham
> > Sent: Monday, November 21, 2011 8:57 AM
> > To: 'Velocity Aircraft Owners and Builders list'
> > Subject: Re: REFLECTOR: Odd fuel stain?
> >
> > General rule of thumb I use is no more than 500fpm climb when above 75%
> > tanks. This helps prevent dumping fuel out your vent which you cannot
> > calculate very easily. The only solution to this would be to run your
> vent
> > 1-2 feet forward so that your strake angle does not exceed the top of the
> > vent.
> >
> > IO-540 (260HP) RG should be climbing between 120-130kias, 300HP Lycoming's
> > and Continentals should be 130-145KIAS. *Note that the IO-550 RG's at 135
> > will be above 500FPM so you may have to climb at a faster speed than 140.
> > Turbo charged aircraft with RG systems are between 145-165KIAS in a climb.
>
> >
> > FG aircraft, speeds in climb will vary about 10kts less.
> >
> > Also, make sure your vent is scarfed into the wind so that you continually
> > pressurize your tanks and don't create a vacuum. Vent lines in the back
> > should be treated the same as your main feed lines. You want a continual
> > downhill slope into the tanks so that you don't have any low point in the
> > vent lines otherwise you may get some fuel stuck in the vent that cant
> > pressurize itself out very easily which will lead to uneven feeding.
> >
> > John
> >
> > -----Original Message-----
> > From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> > Behalf Of Scott Baker
> > Sent: Monday, November 21, 2011 7:47 AM
> > To: Velocity Aircraft Owners and Builders list
> > Subject: Re: REFLECTOR: Odd fuel stain?
> >
> > Maybe not the negative-G, but very likely the steep pitch up maneuver. I
> > have many times seen (from the ground) a vapor trail of fuel exiting the
> > vent tube from Velocity aircraft doing high performance takeoffs at
> > Sebastian.
> > Scott B.
> >
> > ----- Original Message -----
> > From: "Scott Derrick" <scott at tnstaafl.net>
> > To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> > Sent: Sunday, November 20, 2011 7:18 PM
> > Subject: REFLECTOR: Odd fuel stain?
> >
> >
> >> So after design/install of a new forward cabin heater system I took the
> >> bird for a test flight. I as also testing a new oil temperature sensor
> >> which is working fabulously!
> >>
> >> Played around to the north of GNT getting the plane setup for LOP at 9500
>
> >> and playing with different settings of the heater controls, there is a
> >> separate control for pilot and co-pilot positions, plus the oil flap
> >> provides full or reduced air flow.
> >>
> >> The problem occurred when I did a walk around in front of the hanger
> after
> >
> >> the flight and saw a bit of a fuel(blue) stain on the rear cowl! Thats
> >> really odd I thought! It started about a foot to the rear of the fuel
> >> vent and was kinda wispy looking, about a foot+ long.
> >>
> >> I was pretty upset as I don't like fuel leaks, who does, and we are
> >> planning on flying to Tahoe Tuesday morning. I was contemplating where it
>
> >> could have come from, There is no way it cam from the engine compartment,
>
> >> it would have pooled at the low point in the bottom cowl and come out the
>
> >> drain holes, and this was nowhere near that. Plus the fact, is was
> >> directly in line with the fuel vent, but why would it spit fuel in
> flight!
> >>
> >> Then I had an idea.
> >>
> >> When I came back to the pattern the airport crowd requested a low pass,
> >> you know an altimeter/compass check, so I sucked the gear back up and did
>
> >> a 185 knot 100 ft pass down the runway. Turning about 2600 RPM, at mid
> >> field I pulled up into a steeper than usual climb, about 4,000+ ft per
> >> minute, the speed rapidly unwinding, the altimeter doing the reverse. At
> >> the top, about 1,000 agl and now at 120 knots I pushed over a little more
>
> >> aggressive than I usually do, going just a bit negative G for 5 seconds
> or
> >
> >> so, leveled off and made a sedate pattern to landing.
> >>
> >> My fuel tanks are almost full, about 26 gallons in 30 gallons tanks.
> >>
> >> Now I wonder did the negative G maneuver cause the fuel to spit out the
> >> vent? Anybody else experience a similar thing?
> >>
> >> Scott
> >>
> >> --
> >> We are all here for a spell; get all the good laughs you can.
> >> Will Rogers
> >> _______________________________________________
> >> To change your email address, visit
> >> http://www.tvbf.org/mailman/listinfo/reflector
> >>
> >> Visit the gallery! www.tvbf.org/gallery
> >> user:pw = tvbf:jamaicangoose
> >> Check new archives: www.tvbf.org/pipermail
> >> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> >
> >
> > _______________________________________________
> > To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery! www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> _______________________________________________
> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
> _______________________________________________
> Visit the gallery! tvbf:jamaicangoose
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