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<P>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. </P>
<P>Vicente Bortone<BR></P>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">-------------- Original message -------------- <BR><BR>> I know everyone ignored my first response about this - but I think it deserves <BR>> consideration, guys. The hopper setup probably WORKS simply because it is <BR>> closer to the suction source (proximity to the spraybar/venturi). Being closer, <BR>> it is easier for the engine to "draw" the fuel. <BR>> <BR>> I really don't think there's a lot more to this issue than suction. <BR>> <BR>> Bob P. <BR>> Pump-running-non-suction OS user and ARF flier <BR>> > <BR>> > From: Brian Young <B.YOUNG8070@SBCGLOBAL.NET><BR>> > Date: 2004/08/13 Fri AM 08:52:12 EDT <BR>> > To: discussion@nsrca.org <BR>> > Subject: Re: hopper theory & practice <BR>> > <BR>> > Dave I think that your last couple of questions are what occur. If someone <BR>> would put one in a hover for a few minutes to setup equilibrium it should lean <BR>> once replenishment from the main tank becomes established in the new <BR>> orientation, anyone want to try that? ;) <BR>> > <BR>> > <BR>> > ronlock@comcast.net wrote: <BR>> > <BR>> > Ive been a hopper tank diss-believer for years. I also wonder why many <BR>> continue to report benefits. What's responsible for the benefit? <BR>> > <BR>> > I'm in agreement with Nat, and what "I think" Jerry has said regarding the <BR>> fuel system with a FULL hopper tank being a column of fluid, and the hopper <BR>> would have no benefit. <BR>> > <BR>> > Maybe hopper serves to eliminate foaming and bubbles? Do I understand heli <BR>> pilots use hoppers for that reason? <BR>> > <BR>> > In practice do we usually have some air in the hopper? Or do we usually have <BR>> a hopper tank that is flexible? Might we be drawing from the hopper without <BR>> replenishing from the main tank during a vertical? Then the hopper gets <BR>> replenished during level lines? <BR>> > <BR>> > Still wondering, Ron Lockhart <BR>> > -------------- Original message -------------- <BR>> > <BR>> > > >Matt, <BR>> > > >With or without the hopper tank we still have a solid column of <BR>> > > >incompressible fluid for gravity and G's to play its tricks on. I <BR>> > > >contend if it runs ok with the hopper it will run just as well <BR>> > > >without. Nat <BR>> > > <BR>> > > Nat, <BR>> > > <BR>> > > While not exactly accurate as stated, your point is well taken. Your <BR>> > > hypothesis has some merit when the tank is full, but it falls short <BR>> > > anytime else (which is most of the flight). Adding just a small <BR>> > > amount of air causes the system to become compressible (just like the <BR>> > > brakes on your car). <BR>> > > <BR>> > > Jerry <BR>> > > -- <BR>> > > ___________ <BR>> > > Jerry Budd <BR>> > > mailto:jbudd@qnet.com <BR>> > > ===================================== <BR>> > > # To be removed from this list, go to http://www.nsrca.org/discussionA.htm <BR>> > > and follow the instructions. <BR>> > > <BR>> > <BR>> <BR>> Bob Pastorello, El Reno, OK, USA <BR>> rcaerobob@cox.net <BR>> www.rcaerobats.net <BR>> <BR>> ===================================== <BR>> # To be removed from this list, go to http://www.nsrca.org/discussionA.htm <BR>> and follow the instructions. <BR>> </BLOCKQUOTE></body></html>