REFLECTOR: fuel feed - my solutions
Brian Michalk
michalk at awpi.com
Sat Feb 26 11:48:52 CST 2005
I wondered what it meant by less than .5 PSI. It says it's a flapper type
silicon impregnated disk. I would think it would be a fairly low cracking
pressure. Of course it would probably reduce fuel flow.
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 11:07 AM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: fuel feed - my solutions
Brian,
In our application, the first valve may not let fuel through at all, given
our low head. The second valve, with 0 psi cracking pressure, is probably a
flap valve. Based on extensive process experience with similar valves, if
it cost more then 10 cents, its probably over-priced. The only time it'll
fail is when you are relying on it.
Chuck
Do Not Archive
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of Brian Michalk
Sent: Saturday, February 26, 2005 10:02 AM
To: Velocity Aircraft Owners and Builders list
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
>
> 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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