Printing out and copying to my build log...great stuff
Luis
On Wednesday, June 14, 2017 2:18 PM, Jeff Scott via KRnet
<krnet@list.krnet.org> wrote:
Accepted practice is a flow rate one point five
times the maximum engine requirement in the worst
possible flight configuration, generally nose
high climb. You can't have too much fuel flow
capacity unless you are over powering your carb.
Another rule of thumb that works well on our type
of engine is that fuel burn will be 1/2 pound of
fuel per horsepower per hour. My 0-200 for
example at 65 percent power = 65/2 =32.5 pounds /
6 ppg = 5.41 gph, very close to actual.
Just remember, silence in flight is for sail planes...............
Larry Flesner
---------------------------
Larry's fuel burn rate is correct. Of course when calculating minimum fuel
flow, one wants to use 100% power setting at your worst fuel flow rate. As
Larry says, that's usually steep climb and while you are low on fuel.
The 1.50 times delivery for maximum fuel flow is for gravity feed systems. A
pressurized fuel system requires only 1.25 times of maximum fuel flow for the
engine. So, my gravity fed O-200 requires a minimum flow rate of 100% x .5
lb/hp/hr / 6 ppg x 1.5 = 12.5 gph minimum flow through the carburetor.
Larry's O-200 with fuel pumps supplying the carb only requires a maximum fuel
flow test of 10.42 gph.
-Jeff Scott
Los Alamos, NM
----------------------------
From the FAA handbook and fuel flow testing...
For gravity-flow fuel systems, the fuel flow rate must be 150
percent of the takeoff fuel consumption of the engine. For fuel
pump systems, the fuel flow rate for each pump system (main
and reserve supply) for each reciprocating engine must be 125
percent of the fuel flow required by the engine at the maximum
takeoff power. However, the fuel pressure, with main and
emergency pumps operating simultaneously, must not exceed
the fuel inlet pressure limits of the engine.
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