REFLECTOR: fuel feed - my solutions
Wayne
wowens at darientel.net
Sun Feb 27 09:06:55 CST 2005
I'm using two of the .5 jobs for an alternate air source in the top of the loop before the vent line goes to the bottom of the fuselage. If the fuel vent iced over I hope they will provide cabin air to the fuel tanks. If the bird is upside down they shouldn't allow fuel to leak inside the cabin.
Wayne
----- Original Message -----
From: Brian Michalk
To: Velocity Aircraft Owners and Builders list
Sent: Saturday, February 26, 2005 10:01 AM
Subject: RE: REFLECTOR: fuel feed - my solutions
McMaster has a lot of check valves.
This one says less than .5 PSI cracking pressure.
http://www.mcmaster.com/catalog/111/gfx/large/47245kp1l.gif
This one says 0 PSI cracking pressure.
http://www.mcmaster.com/catalog/111/gfx/large/7909kp1l.gif
These came from this page:
http://www.mcmaster.com/nav/enter.asp?pagenum=389
Brian Michalk <http://www.michalk.com>
Life is what you make of it ... never wish you had done something.
Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
musician, home-brewer, entrepreneur and barely single
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Chuck Jensen
> Sent: Saturday, February 26, 2005 4:27 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: RE: REFLECTOR: fuel feed - my solutions
>
>
> Jerry,
> All check valves has some pressure differential which we can ill
> afford to loose when the fuel head is measured in inches.
> Probably the strongest reason for leaving them off is if you do
> have a little non-uniform fuel flow during your flight, at least
> when you land, the tanks will self level for your next
> flight--assuming your on the level when you parked.
>
> Chuck
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Jerry.Brainard at anthem.com
> Sent: Friday, February 25, 2005 5:22 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: fuel feed - my solutions
>
>
>
> Just because I don't know - is there a reason not to put a check valve in
> line on the strake feed lines? My thought is that this would prevent
> retrograde flow into a tank that is on the low side (out of rig) or has a
> leaking cap. I can think of many scenarios where one might be confused as
> to what is happening, but it would seem to resolve any issue with pulling
> fuel into a tank from the feed line. Of course there is also added
> complexity and another failure mode to consider.
>
> -jerry
>
> 513-484-1328
> 513-336-5949
>
>
>
>
>
>
>
> Don19dw at aol.com
>
> Sent by: To:
> reflector at awpi.com
>
> reflector-bounces cc:
>
> @tvbf.org Subject:
> REFLECTOR: fuel feed - my solutions
>
>
>
>
>
> 02/25/2005 04:38
>
> PM
>
> Please respond to
>
> Velocity Aircraft
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> Owners and
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> Builders list
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>
> As a result of my accident in June 1999, caused by a leaking fuel cap, I
> made the following changes.
> 1) Added the sump tank "low fuel" warning system per Velocity
> plans, except
> located float slightly lower. The "low fuel" warning would have allowed we
> to reach an airport prior to fuel exhaustion from right tank and sump
> tank.and thus prevented the accident.
> However then during later flights, especially in turns would get flashing
> "low fuel" warnings which made me very nervous. To trouble shoot the
> problem I removed the rear seats and spar cover so I could visually see
> sump tank in flight. Using "T" fittings I added a vertical clear
> sight tube
> between top sump vent port and bottom outlet port plus a light shinning on
> the tube to see fuel level from my pilots seat. As Scott Swing suggested,
> the sloshing of the fuel in the sump tank was causing the flashing "low
> fuel" warning with little or no lowering of fuel level.
> 2) In order to solve flashing "low fuel" warning, I added a time delay
> relay set at 6 seconds, before warning light went on, and have
> not had that
> problem since.
> 3) Installed a manual shut off valve in fuel line from each strake into
> sump tank. These left and right shut off valves are actuated by cables and
> small levers on each side of keel at pilots hip. These valves
> could be used
> in flight to isolate either strake tank from the sump if the fuel level in
> one side or the other is seen to be dangerously low. If the sump vent is
> closed, the fuel pump should "suck" fuel from the open fuel
> strake. However
> the argument for a closed sump vent is valid "to suck fuel" only if empty
> tank is shut off, otherwise air is "sucked" from the empty tank, rather
> than fuel sucked from the other tank. That apparently is what happened
> prior to my accident. So far have never used my added valves in flight.
> (However these valves are handy during servicing and I recommend adding
> them for that reason alone)
> 4) Added an instrument panel note: " Warning: at least every 30 minutes,
> check fuel level in each strake tank. If an unusual balance is
> seen, ASSUME
> fullest tank is unusable"
> 5) After rebuilding the airplane, discovered the turn and bank
> indicator in
> the instrument panel, was not installed vertical, about 1/2 bubble off
> vertical. Once that was corrected, had to shim left rudder out 1/4 inch at
> trailing edge. Plane now flies perfectly level and straight and have not
> had any unusual fuel level problems since.
> 6) Finally check fuel caps are tightly closed and properly lubricated.
>
> This may have been suggested to Jim already. During flight, have you held
> slight pressure on one rudder or the other, to see if fuel tank levels
> equalize? If that occurs, then I strongly suspect plane is not flying
> perfectly level and straight.
> Don White N19DW XL/RG
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