hopper theory & practice
vicenterc at comcast.net
vicenterc at comcast.net
Fri Aug 13 06:03:01 AKDT 2004
I agree with Bob. It is just pressure drop on the lines. The longer the lines more pressure drop we will have. That is why we need to add a pump when we don't have the hopper thank abd the fuel tank is close to the CG.. Also, the hopper tank acts as a reservoir that will supply the additional fuel required during critical positions. If the critical posistion last too long you could have a problem as Brian said. That is why the pumps are more reliable in the long critical positions.
Vicente Bortone
-------------- Original message --------------
> I know everyone ignored my first response about this - but I think it deserves
> consideration, guys. The hopper setup probably WORKS simply because it is
> closer to the suction source (proximity to the spraybar/venturi). Being closer,
> it is easier for the engine to "draw" the fuel.
>
> I really don't think there's a lot more to this issue than suction.
>
> Bob P.
> Pump-running-non-suction OS user and ARF flier
> >
> > From: Brian Young
> > Date: 2004/08/13 Fri AM 08:52:12 EDT
> > To: discussion at nsrca.org
> > Subject: Re: hopper theory & practice
> >
> > Dave I think that your last couple of questions are what occur. If someone
> would put one in a hover for a few minutes to setup equilibrium it should lean
> once replenishment from the main tank becomes established in the new
> orientation, anyone want to try that? ;)
> >
> >
> > ronlock at comcast.net wrote:
> >
> > 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.
> > >
> >
>
> Bob Pastorello, El Reno, OK, USA
> rcaerobob at cox.net
> www.rcaerobats.net
>
> =====================================
> # To be removed from this list, go to http://www.nsrca.org/discussionA.htm
> and follow the instructions.
>
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