REFLECTOR: fuel feed - my solutions

Chuck Jensen cjensen at dts9000.com
Sat Feb 26 11:07:10 CST 2005


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.
  The image "http://www.mcmaster.com/catalog/111/gfx/large/47245kp1l.gif" cannot be displayed, because it contains errors. <http://www.mcmaster.com/catalog/111/gfx/large/47245kp1l.gif> 
http://www.mcmaster.com/catalog/111/gfx/large/47245kp1l.gif
 
 
This one says 0 PSI cracking pressure.
  The image "http://www.mcmaster.com/catalog/111/gfx/large/7909kp1l.gif" cannot be displayed, because it contains errors. <http://www.mcmaster.com/catalog/111/gfx/large/7909kp1l.gif> 
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                            
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> REFLECTOR: fuel feed - my solutions                              
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>                       02/25/2005 04:38                           
>                                                                      
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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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