Sorry I dont understand the confusion regarding Fuel Flow Gauge ..
Yes of course there are 2 needles , for 2 engines .. and each one indicates individually ..
therefore you noted 25 GPH Indication would report 25 GPH PER ENGINE
at a cruise with 60% Power then would indicate approx 12.5 GPH Per Engine giving a Total of 25 GPH
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No ILS for this girl.
Apparently IRL thereās a placard on the instrument panel āAuto Pilot Not Fittedā.
Hand flying all the way, Arann Islands Galway Bay.
https://flightsim.to/file/15220/blackbox-britten-norman-bn-2-islander-aer-arann-ei-bce
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Hi
But my gauges are indicating 25 gal/hour on EACH gauge?
I am currently.
at 4000 feet with auto pilot set for level flight
revs at 2200
manifold press at 22 inch
Lean the mixture to read just over 12 gal/ hour (almost the bottom of the gauge)
Mixture controls are almost at cut off both on my bravo throttle and in the 3d cockpit
the speed is just under 100 Knots.
To get a cruse speed of 120 knots I need to increase the mixture to use 20 gal/hour in EACH tank.
This is with the default load
Please advise if this seams correct to you.
Best wishes
Bob
PS
I just decided to throw all the passengers and cargo out to see if this made any change.
No change still 120 knots at the same engine settings.
WHY are you leaning the mixture to adjust the power ??
set BEST Mixture for altitude and then use Throttle levers to set 60% Power
HOWEVER All this is pretty null and void as the Engines have been tweaked for V1.1 But the process remains the same
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Found a pilot report regarding the islander
Having slowly brought the power back up on the port engine, I set 24/24 (24in of manifold pressure and 2,400rpm), trim forward carefully and concentrate on holding the aircraft exactly level at 2,500ft while Simon helpfully notes down the speed and fuel flow.
The IAS of 128kt means a TAS of 133kt, while the fuel flow is about 45 litres per hour on each side. Pulling the power back to 21/21 the speed dips to 114 IAS (119 TAS) while the total fuel flow reduces to around 80 lph.
Taken from
https://www.pilotweb.aero/features/flight-tests/flight-test-britten-norman-bn-2-islander-1-5293959
Hi
I was just adjusting the mixture to try and get the 12.5 Gal/hour/engine fuel flow
As per my original post I feel in normal operation I the fuel consumption / flow is too high
I look forward to the patch and see if it is better.
Thanks for your advice.
Best wishes
Bob
Hi
Thanks
For me to get close to 120 knots indicated air speed I seam to be using 20 gal/hour/engine
20 gal/hour/engine must approximately 90 lph /engine. Total 180 lph
Best wishes
Bob
More tweaking to do but Unless I missed something ā¦
80 - 90 LPH ( 22 GPH ) seems about right no ??
Hi but I am using 20 gal/hour/side
40 gal/hour total
40 us gal/hour is about 150 l/h
40 imp gal/hour is about 180l/h
Best wishes
Bob
Hang on ā¦
Gallons Litres per side per engine USG Imperial ?
Different FDE ..
Time to sit back and re-evaluate 
OK SO now I have ----
124 Kts IAS
2400 Prop RPM
24 Inches MP
Approx 24 US GPH total ( 90 LPH)
@ 60 % Throttle and ābest mixtureā
whereas reducing to
2100 RPM
21 Inches
gives me approx 115 Kts and approx 21 GPH ( 80 LPH)
we getting somewhere ?
Looks like rule of thumb - 24, 24, 24 / 21, 21, 21, etc
OK how about this
I am currently cursing at 5000 feel 120 Knots
20/20 for RPM and Manifold pressure
Fuel flow is 20 gal/hour on each engine, as read from the gauges in the aircraft cockpit.
so 40 gal/hour total
if I lean it to try and get the 12 gal/ hour/engine the speed drops to less that 100 knots
does this sound correct or is the fuel flow to high?
Ok
I am trying to copy your settings
Set 2400 rpm
60% throttle
but this gives me only 20 inch of manifold pressure
If I lean the mixture to get 12 gal/hour / engine
the sped is less than 100 knots
this is at 4000 ft
this seams a little odd?
Try this it is out of my Islander POH
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Hi
Thanks
I copied the
59%
4000 ft
2100 RPM this gave 20 inch manifold pressure (Close to the table)
120 knots
22 gal/hour/each side so 44 gal/hour total. With the mixture leavers full forward.
Where should they be set?
Also
The table says fuel Consumption Gal/hour. Is this this each side or total?
Thanks in advance if you can help.
Best wishes
Bob
Lean your mixture until you start to run rough then move them forward until you get smooth running between 19-23 gph just remember this is for the 260hp engines for the 300hp lean 12-20 gph @ 4000 density alt
Hi
Thanks but this is where I am losing the plot. The engines donāt run rough until I have lean to 15% where I am doping to under 100 Knots
If I lean to say 50% my fuel flow is up to 25 gal/hour/side
Best wishes
Bob
260 HP and 300HP?
I did not know we had a choice of engines?
I am using the default Black Box livery if that helps.
I think I have to intervene here because Iām afraid you are all missing the point hereā¦
First thing to calrify: What is the fuel flow gauge displaying?
Is the left and the right part the fuel flow to the left and right engine, respectively? I would think so. In this case, we would have ~21 GPH for each engine.
When I look at the simvars, I get this (data taken simulatenously to the screenshot):
The fuel flow per engine is ~13GPH according to the simvars.
Just to verfy this, here is a plot of the total fuel quantity:
In ~30s, the quantity drops by ~0,21gallons, this make 25,2 GPH which fits to the 13GPH per engine from above.
So the simvar-values do not fit to the gauge display and I think that is the source of the whole confusion here.
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