I need to do a fuel flow test before my final inspection at the maximum climb angle. What is everyone seeing for their max climb angle?
I need to do a fuel flow test before my final inspection at the maximum climb angle. What is everyone seeing for their max climb angle?
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Josh Esser
Flying SS7
Rotax 914iS
AirMaster Prop
Edmonton, AB, CWL3
I don't know the actual Kitfox number, but it probably varies with your particular engine and GVW. I just used the FAA recommended angle of 25 degrees (better check this, my memory may be off).
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
I just did my IV with Rotax 582 at 25.4 degrees and got 7.5 gph.
My DAR said that I should see 150% of take-off power fuel flow which would be 10.5 gph.
I asked John McBean and he replied with the following...
Do not have a published procedure..
Where did you get the 25.5 degrees ? Generally 15 Degrees if I remember the FAA guidelines..
Where is the 150% gravity feed requirement on a pump required system... or pressure system... It's not..
For a gravity feed system 150% is required.. for pump systems 125% for each pump system.. but technically you should have an aux pump.
Generally.. one can convert fuel to lbs.. and calculate 1/2 lb per horsepower. 582 is 65 hp.. so 32.5 lbs. fuel is 6.0 lb per gallon.. so 32.5 / 6 = 5.42 gallons * 125% = 6.775 gallons per hour..
Or.. HP / 12 = X 65 / 12 = 5.42 gph.
All that being said.. be sure the fuel system is clear of obstructions.. all going downhill and minimal bends.. there is also an approximate .02 psi of pressure at 30 mph on the pressure vent of the fuel tank.
Your only option would be to increase the inner diameter of the fuel line to increase the flow.
However, your 7.5 gph is adequate given the equation above. Hope that helps.
Fly Safe !!
John McBean
Ph 208.337.5111
www.kitfoxaircraft.com
"The Sky is not the Limit... It's a Playground"
John says I have a "boost pump required system".
The old build manual had no such requirement. When did that come about? Am I nuts not to have an electric boost pump?
jon
Kitfox IV 1050, C180. Now I have two backcountry planes! WooHoo!
Hi Jon,
To technically meet the letter of the law, according to 14CFR 23.955, you must have a minimum flow rate of 150% of full throttle fuel flow (at sea level would be the max. requirement) with a gravity system. With a fuel pump system the requirement is 125%. I believe Rotax says the 582 requires 8 gph at max. takeoff power? With a pump, that means you should have a minimum of 10 gph tested flow rate. 7.5 gph seems pretty low to me.
Not sure of the exact angle, but when I tested my 912 ULS installation, I got the mains up on a couple of car tire ramps. With 1 gal. in each wing tank, and 1 gal. in the header tank, I measured the flow rate at over 17 gals./hr. According to Rotax, the takeoff power requirement for my engine is 7.1 gal./hr.
John Evens
Arvada, CO
Kitfox SS7 N27JE
EAA Lifetime
Chap. 43 honorary Lifetime
John, where did you measure the fuel flow, right at the carbs, or just before or after the fuel pump? I measured right at the carbs at first and got around 7 gph. Then I measured just before the fuel pump and got a lot more. A fuel pump that is not operating has a lot of restriction to gravity flow thru it. It apparently is not zero, but may be just barely enough to keep the engine running at high power.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS