hopper theory & practice

[George Kennie]

Hey Jim,
I'm with you on this one! You know those Dave Brown CA Applicators,(
the semi- transparent ones). I think if you could get one the same
size with a tube molded into the opposite end so that it now has an
inlet and an outlet tube you could stick it in the line right at the
carb you would be bullet proof. Shouldn't be all that difficult for
the mfgr. to draw some up and market same. I'd call it "The Belch
Squelch".
Georgie

Jim_Woodward at beaerospace.com wrote:

>
> 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 be reduced to a section of fuel tubing
> that is "bubbled"?  Would the "bubble" work is there was a
> separate entry and exit point like the ven t and clunk lines of
> the hopper tank?  If the bubble was 5 times larger than the ID of
> fuel tubing would it work?
> Thanks,
> Jim W.
>
>
>  ronlock at comcast.net
   Sent by:                                    To:
   discussion-request at nsrca.org        discussion at nsrca.org,
                                       discussion at nsrca.org
   08/13/2004 08:34 AM                         cc:        Jerry Budd
   Please respond to discussion        <jbudd at QNET.COM>
                                               Subject:        Re:
                                       hopper theory & practice
>
>
>
> Ive been a hopper tank diss-believer for years.  I also wonder why
> many continue to report benefits.  What's responsible for the
> benefit?
>
> I'm in agreement with Nat, and what "I think" Jerry has said
> regarding the fuel system with a FULL hopper tank being a column
> of fluid, and the hopper would have no benefit.
>
> Maybe hopper serves to eliminate foaming and bubbles?  Do I
> understand heli pilots use hoppers for that reason?
>
> In practice do we usually have some air in the hopper?   Or do we
> usually have a hopper tank that is flexible?   Might we be drawing
> from the hopper without replenishing from the main tank during a
> vertical?    Then the hopper gets replenished during level lines?
>
> Still wondering, Ron Lockhart
>
> -------------- Original message --------------
>
> > >Matt,
> > >With or without the hopper tank we still have a solid column of
>
> > >incompressible fluid for gravity and G's to play its tricks on.
> I
> > >contend if it runs ok with the hopper it will run just as well
> > >without. Nat
> >
> > Nat,
> >
> > While not exactly accurate as stated, your point is well taken.
> Your
> > hypothesis has some merit when the tank is full, but it falls
> short
> > anytime else (which is most of the flight). Adding just a small
> > amount of air causes the system to become compressible (just
> like the
> > brakes on your car).
> >
> > Jerry
> > --
> > ___________
> > Jerry Budd
> > mailto:jbudd at qnet.com
> > =====================================
> > # To be removed from this list, go to
> http://www.nsrca.org/discussionA.htm
> > and follow the instructions.
> >


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