REFLECTOR: Fuel Vent (used to be Odd Fuel Stain)
Robert Wood
slvegl99 at aol.com
Mon Nov 21 14:56:57 CST 2011
In 2001 we were not making that bend forward, only to the top then back down. At this point I doubt that it is worth tearing the headliner out.
Bob Wood
On Nov 21, 2011, at 3:40 PM, Brooke Wolf <bwolf1 at tds.net> wrote:
> 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
>
>
>
>
> <IMG_0188.jpeg>
>
>
>
>> 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
>
> _______________________________________________
> 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
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