Return-Path: Received: from YCC.COM ([204.155.150.41]) by truman.olsusa.com (Post.Office MTA v3.1.2 release (PO203-101c) ID# 0-44819U2500L250S0) with SMTP id AAA27447 for ; Wed, 7 Oct 1998 21:01:54 -0400 Received: from YccPrimaryDomain-Message_Server by YCC.COM with Novell_GroupWise; Wed, 07 Oct 1998 20:07:44 -0500 Message-Id: Date: Wed, 07 Oct 1998 20:03:25 -0500 From: "Bill Gradwohl" To: lancair.list@olsusa.com Subject: Fuel System Question Mime-Version: 1.0 Content-Disposition: inline X-Mailing-List: lancair.list@olsusa.com <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> If an aircraft had a single fuel tank, then getting fuel to the engine would involve the following major pieces of equipment connected in series: Fuel tank, shut off valve, fuel pump, regulator valve, pipe to engine and a pipe back to the fuel tank for the overflow. I'm forgetting about fuel filters and other extraneous gear for redundancy. Because we have multiple tanks, we end up manually selecting which tank feeds fuel to the engine during any time period. We also end up having multiple fuel pumps, one per tank, not for redundancy, but because we have to. What is wrong with the following idea. I'm sure there must be something wrong with it or it would have been implemented long ago. The wings are mounted at an angle to the horizontal plane. Gravity would take any fuel and attempt to empty the tanks if given an opportunity. If both tanks emptied into a tiny 1 pint reservoir and that reservoir was considered the "tank" in the first paragraph, wouldn't that get rid of the manual switching of tanks, and reduce the amount of plumbing, connections and weight? I am assuming that non banked flight is 99.9% of all flight and therefore gravity should act equally on both wing tanks. One way valves could prevent reverse flow but that shouldn't even be a problem except in relatively rare situations where centrifugal forces are present as in turns and other flight where the wings aren't level. If one tank had more fuel in it than the other tank, that tank would also exert more pressure into the tiny reservoir and should empty at a faster rate till it is equal with the other tank. If there were no reverse flow valves, the fuel would seek its level in both tanks. What is wrong with this? Bill Gradwohl IV-P builder N858B