FAA document AC 90-89A (now superseded by AC 90-89B) SECTION 11. ADDITIONAL ENGINE TESTS, paragraph 1.e. Fuel Flow and Unusable Fuel Check: states the method to determine the fuel flow needed by amateur built aircraft. At the airworthiness inspection for my KR-2 the FAA inspector wanted to see the data and pictures of the tests that I did to determine the actual fuel flow. For pressurized systems (using a fuel pump) the flow must be at least 1.25 times the WOT requirement and setting at 5 degrees above the maximum angle of attack and minimum fuel in the tank. For gravity feed systems the number is 1.50 times the WOT requirement. For engine driven fuel pumps, that may require some creative plumbing for the test. I used a quart catch jar and timed (in seconds) to fill it. Put a shut off valve on the end of the hose so you or your assistant can control the start and stop flow into the jar. I used 3/8-inch tubing for all fuel lines. My flow numbers were 21 gal/hr for the engine pump and 23 gal/hr for the Facet pump. Those numbers are way over the minimum requirements. Don't know what 1/4-inch tubing would yield. Since my KR-2 has both an electric Facet and engine driven fuel pumps and two fuel tanks, the tests had to be repeated 4 times to measure all line-ups. Handling a fuel hose behind an invisible meat chopper in hurricane force winds does present some hazards to your health. A calibrated inline fuel flow meter will vastly simplify making the measurements.
Sid Wood Tri-gear KR-2 N6242 Mechanicsville, MD, USA ------------------------------------------------------------------ Good Info Brian? my plans were to mount it lower than the wing cells?. so I?m okay there? Also transferring to main tank but by 1/4? lines?.. then return overflow to one wing cell again via 1/4 ? Considering more volume under pump pressure than gravity flow overflow to wing? I would appreciate any comments on line size.. or am I being to engineered? jw Joe. E. Wallace jwallacep51 at gmail.com > On Aug 8, 2015, at 16:27, brian.kraut--- via KRnet <krnet at list.krnet.org> > wrote: > > Keep those Facet pumps low. They don't do good with pulling a prime > uphill which I learned on my aux wing tanks transferring to the header > tank. I originally had my pump mounted on the back side of the header > tank, but I moved it down low on a doubler on the front of the spar when > I had an issue with it not sucking up a prime. > > > -------- Original Message -------- > Subject: Re: KR> fuel line through the spar caps? > From: ppaulvsk via KRnet <krnet at list.krnet.org> > Date: Fri, August 07, 2015 11:27 am > To: KRnet <krnet at list.krnet.org> > Cc: ppaulvsk <ppaulvsk at aol.com> > > I wasn't planning on going to the spar cap. Just the center of the web. > After the holes are drilled. I'm putting a 1/8" plywood doubler over > them.Then run the tube threw it. Like what Mark said. My goal is to keep > the fuek coming out of the tanks in the same plain befor going though > the firewall to the duel Facet pumps. Larry, there is a horizontal brace > on the back side of the spar and my floor covers the front side. Like > most KR-2S >
