Fuel Consumption

Hi Mike/ John,

I use True airspeed (130 knots) as my target - its easier than accommodating MAP, at higher altitudes (5000-10,000 ft)

My Airmaster is set to 5000 rpm in Cruise mode.I can change this either by going to Manual Mode or in the Settings but for the most part choose not to.

My Cruise MAP is usually around 25" at 2000ft.

I get soot on one  flap - I put it down to the start fuel enrichment / choke system.

My average fuel consumption can vary from 13.25L/hr - near 15 L/hr depending on what I am doing. Lots of touch and goes will increase my average, as will any other climb / descent activity. Cruise (level flight) is where the best econamy occurs.😈

Thanks,

I use an Airmaster CS prop and are aware of how to use it. It's great that you are using less fuel than I do. My point is that I'm using 20 l/h and I know others use a lot less.
Unfortunately it's  to no help getting to know that others use less - I already know that.

Hi John

I don’t know if you have owned the aircraft since new, but have you verified the main jet size is stock? 

I think that's a good suggestion to check the main jets. How old are the carbs and engine BTW? Are the diaphragms perfect?

I would add check everything about the "choke", there are ways to assemble it wrong and there are seals to leak.

Picking up other points -

I don't get a sooty exhaust pipe or black on the bodywork (Europa), just a bit of yellowish staining.

I don't claim the lph figures I've given to be spot on, my co-owner and I haven't run careful trials. It's just change in sight tube reading from start to engine off, plus fuel added, divided by airtime from t/o to landing. We get anything from 10 (suspect!) to 18lph. He tends to go places @ 110-120kts and sees 18. I often bimble at 90-100 and see 13-16.

The prop is CS with Airmaster's default settings so I tend to use 5000 <25" and 5400 for 26"+.

There is something wrong with regularly using 20lph!

"Unfortunately it's  to no help getting to know that others use less - I already know that."

True!  However knowing how other's manage/set their engine/prop, type of flying - fuel consumption, may assist in your diagnosis.

"Even at 55% i.e. 4300 rpm and manifold vacuum of 2500"

Other than in circuit / deliberate slow flight, I don't operate my engine below 5000 rpm.

😈