Fuel foaming

[Fletcher, Richard]

I have heard that adding a capful of Amorall to a gallon of fuel eliminates
all fuel foaming.
 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of Rcmaster199 at aol.com
Sent: Friday, August 13, 2004 4:52 PM
To: discussion at nsrca.org
Subject: Re: hopper theory & practice


If foaming is your problem, then a bladder tank will likely help. If it is
not, then there will be no change, real or imagined, for that reason. There
could be other problems tho.
 
Make little mistake: if the fuel is foaming, the pump will most likely
cavitate and be of little use in fuel delivery. I have long suspected this
to be a significant contributor to pump problems we have been reading, by so
many of us.
 
To solve fuel foaming, isolate the tank from the vibratory source as much as
possible. Any fuel delivery system will benefit, doesn't matter if it's
simple pipe pressure, diaphragm pump, cline regulator or pressurized tank
 
MattK

Any one using a bladder tank with their Webra 145 or 160?  Some poeple at
the local fuel has started using them in sports plane for fuel related
problems.  Seems to sovle thier problems.
 
Randy

----- Original Message ----- 
From: Wayne Galligan <mailto:wgalligan at goodsonacura.com>  
To: discussion at nsrca.org <mailto:discussion at nsrca.org>  
Sent: Friday, August 13, 2004 10:43 AM
Subject: Re: hopper theory & practice


There has to be more pressure(muffler tap) to the main tank then there is
draw from the carb in order for this system to work properly.  Inertia can
effect this as I stated in one of my other posts.  I proved this in my
Prophecy that had the tank higher then the needle valve and when I pressed a
hard negative "g" load it would go lean.  At all other attitudes it ran
fine, i.e, uplines, downlines, snaps, positive maneuvers.  All up it has its
merits but the best is that it reduces the possibility of picking up air in
the main feed line and reducing the possible lean run or lean burp,
something you don't want happening on a turbine or helo engine.  The hopper
will reduce the amount of air that enters the hopper when the main pickup
encounters bubbles of foaming.   The hopper pickup will still be in
bubbleless fuel (fairly fuel tank) if the tank is isolated well enough. Jet
and helo guys use then for this reason.  The other is if you are trying to
move weight forward for a tail heavy airplane. This makes good use of the
fuel transfer and extra tank instead of adding lead ballast.  I think the
bladder tank(like the Tettra) is the best alternative to bubbleless feed and
I am seriously considering using it.  
 
Wayne Galligan
 
- Original Message ----- 

From: Jim_Woodward at beaerospace.com <mailto:Jim_Woodward at beaerospace.com>  
To: discussion at nsrca.org <mailto:discussion at nsrca.org>  
Sent: Friday, August 13, 2004 7:54 AM
Subject: Re: hopper theory & practice



I'll take a stab as why the hopper tanks work.  Liquid may be
incompressible, but it is "movable".  The hopper tank has a fuel entry and
exit point.  Exit point being the clunk line that goes to the engine, entry
point being the vent line.  The hopper tank becomes a reservoir of fuel.
Although I think you can argue that the entry and exit point fuel velocity
(or suction force) is the same, this cannot be said for the middle of the
tank were the suction force is diffused over a larger volumetric cross
section.  The image in my mind is a wind tunnel's stilling chamber.  I think
an interesting question would be this:  How small can a hopper tank be to
still provide the ease of fuel draw we are looking for?  Can the hopper tank

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