REFLECTOR: FUEL FEED [heur]

Wed Feb 16 12:26:05 CST 2005

Tom,

I recommend that you install the vent system as outlined in the manual, Ch 
9.3.5 (on line manuals).

I would not run the vent line into the engine compartment at all.  There can 
be fuel vapors coming out of the vent line and it is certainly flammable.  I 
doubt this would cause a fire in the tank it self, but I wouldn't take the 
chance.

The check valve will open and allow air into the tanks in case the bottom 
vent freezes or gets stopped up by insects.

Ronnie

----- Original Message ----- 
From: "Tom Martino" <tmartino at troubleshooter.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Wednesday, February 16, 2005 12:21 PM
Subject: RE: REFLECTOR: FUEL FEED [heur]

> If the tanks are vented to the upper part of the engine compartment ... I 
> think there is little chance it can ignite unless fuel actually leaked 
> out.  Right, Wrong?  I may have to put a lead on it (to top or bottom?)
>
> -----Original Message----- 
> From: Jim Sower [mailto:canarder at frontiernet.net]
> Sent: Tue 2/15/2005 11:03 PM
> To: Velocity Aircraft Owners and Builders list
> Cc:
> Subject: Re: REFLECTOR: FUEL FEED [heur]
>
>
>
>
> Ron Brown wrote:
>
>
> Tom,
>
> I don't think it is a good idea to vent the fuel system into the engine 
> compartment, especially if you happen to flip upside down during a crash 
> landing.  You will have lots of fuel draining out the vent system into the 
> hot engine compartment.
>
>
> Agreed.  I ended up with a sump vent to the top of the firewall that I can 
> cap off when sump is full.
>
>
>
> With the factory designed fuel vent line routed up to the top of the 
> firewall then back down to exit the bottom of the fuselage, fuel will not 
> leak out of the vent system when the airplane is upside down.
>
>
> I think pretty much all canard vents are like that now.
>
>
>
> One other thought on uneven fuel flow, even if the vents are tied together 
> and the plane is flying level/ball centered: there is a possibility that 
> an air bubble trapped in the vent line with fuel on either side of the 
> bubble can cause an uneven venting of the tanks.  This wouldn't happen if 
> the vent lines always slope upward to the manifold.  I think this may be 
> the scenario that Jim Sower is seeing from time to time.
>
> Nope.  That's the very first thing I fixed.  Actually, the builder had 
> wiped out his LG and had the Velocity factory fix it, and they left one 
> vent to the top of the right strake like it should be, and plumbed the 
> other through the fuselage side into the BOTTOM of the left strake and 
> thence up to the top of the left tank.  There was a permanent 7" column of 
> fuel in that loop.  It's the SECOND thing I fixed (after ensuring that all 
> the vent lines ran uphill to the top of the firewall).
>
>
> I have had it happen a couple of times on long trips after filling the 
> tanks nearly full.  After landing and parking in my hanger, the fuel tanks 
> were 5 or so gallons different and remained that way until I opened the 
> fuel caps.  STRANGE!  Wings are level when parked in the hanger.  Another 
> experiment - I placed a 2 x 6 under one main tire, simulating a wings 
> down.  Guess what - the fuel level difference was MUCH LESS than I have 
> seen in the air.
>
>
> I did that too.  Full tanks will indicate full pretty much no matter what. 
> Jack up one wing and the indications will shift immediately (high strake 
> will have fuel piled up near fuselage where the sender is and will 
> indicate more fuel than is there; low strake will have fuel piled up 
> outboard and lower level next to fuselage where sender is.  Eventually 
> tanks may "even out".  But then again, they may not.
>
>
>
> But again, it could be fuel caps that are not always sealing perfectly for 
> every flight.
>
>
> But if you seal the caps with Al faced tape so there's no possibility that 
> they're leaking, and one tank STILL doesn't transfer,  then what?
>
>
>
> Ronnie
>
> ----- Original Message ----- From: "Tom Martino" 
> <tmartino at troubleshooter.com> <mailto:tmartino at troubleshooter.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org> 
> <mailto:reflector at tvbf.org>
> Sent: Tuesday, February 15, 2005 12:23 PM
> Subject: RE: REFLECTOR: FUEL FEED [heur]
>
>
> My plane flies perfectly.  Not my opinion, it is the assessment of my
> test pilot.  The ball is in the center and the plane flies "hands off"
> straight and level.
>
> I will keep looking.
>
> -----Original Message----- 
> From: Scott Derrick [mailto:scott at tnstaafl.net]
> Sent: Tuesday, February 15, 2005 9:18 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: FUEL FEED [heur]
>
> A leaking gas cap can cause uneven fuel flow but is not the prime
> culprit. A bit of fuel valve lube applied to the O ring once a year will
>
> insure this doesn't happen.
>
> A miss-rigged airplane is most likely the cause. Shim your rudders so
> the ball is right in the middle and you will get perfect fuel flow.
>
> To test, be sure your turn and bank is installed correctly first,
> garbage in garbage out. Then fly, this is the fun part.. Once you see an
>
> uneven condition, press on the rudder that will put the ball in the
> middle. If you want to even up the tanks fast, press on the correct
> rudder so the ball is on the other side for a couple minutes, you'll see
>
> the fuel even up and even go into the opposite imbalance if you keep the
>
> rudder depressed. Then hold the rudder so the ball is centered, fuel
> will flow as it was designed to.
>
> Scott
>
> Tom Martino wrote:
>
>
>
> Well, now that I'm in my test flying mode ... I will really be asking
> a lot of questions.
>
> Here are some of them, as they relate to my fuel system:
>
> 1. What makes the fuel tanks feed unevenly to the header tank/engine?
> (My right tank is feeding twice as fast as my right tank.)
>
> 2. Will that cause a problem when the fast-feeding tank runs out?
>
> 3. I used the larger vent lines for my tanks and tied them al together
>
>
>
> with a manifold, then vented the entire system out through the top of
> my firewall in the engine compartment (about four inches below my naca
>
>
>
> duct). Do you think the system gets enough venting there?
>
> 4. Is there a need for a "whistle" hole in any of the tank vents ...
> for additional venting (like we do with the crankcase breather?
>
> Any help is appreciated from my more experienced Velocitologists J
>
> Tom
>
> N173EX
>
> (A mere 6 hours)
>
> ----------------------------------------------------------------------- 
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