Driggs_15

FSX King Air 350 Range/Fuel Issues

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Ok, so I am using FsPassenger and I finally got my pilot enough points and flight hours to purchase a King Air 350. I don't know why, but, I only get around 600nm and it uses 65% of my fuel source (I took off with full fuel tanks). FSX says it is supposed to give me 1,750nm, though I get nowhere close. My throttle is set at 68% for cruising and the prop RPM is at around 1650. I cruise at 30,000ft. I need a second opinion, I have begun to think about going into the CFG file and changing fuel consumption, unless I have something set wrong.

Here are all my throttle control percentages at cruise:

Throttle: 68%

Prop control: 46%

Condition Lever: 100%

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Even before takeoff, just so I am not taxiing at 50 knots on the taxiways, I set the conditioning levers down to low idle and leave them there.

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25 minutes ago, charliearon said:

Even before takeoff, just so I am not taxiing at 50 knots on the taxiways, I set the conditioning levers down to low idle and leave them there.

So conditioning down to idle you say? Nice to know that there is a way I can avoid taxing above 50knots on this damn aircraft. And so I am not mistaken, the condition throttle is the one to the farthest right?

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32 minutes ago, Driggs_15 said:

So conditioning down to idle you say? Nice to know that there is a way I can avoid taxing above 50knots on this damn aircraft. And so I am not mistaken, the condition throttle is the one to the farthest right?

Those are the ones!  Once the engines are started, both of the levers can be brought down to the low idle position.

 

This is how I do my cold and dark start up for this plane.  I will bring both conditioning

levers down to the fuel cutoff position.  I then turn on the battery and flip up the

left engine start/ignition switch.  I let the engine spin for a few seconds to allow

cooling air to be sucked in and then advance the left conditioning lever slightly till

the engine starts.  Turn off the left ignition switch and do the same procedure

for the right engine.  Both conditioning levers should be in the low idle position.

 

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42 minutes ago, charliearon said:

Those are the ones!  Once the engines are started, both of the levers can be brought down to the low idle position.

 

This is how I do my cold and dark start up for this plane.  I will bring both conditioning

levers down to the fuel cutoff position.  I then turn on the battery and flip up the

left engine start/ignition switch.  I let the engine spin for a few seconds to allow

cooling air to be sucked in and then advance the left conditioning lever slightly till

the engine starts.  Turn off the left ignition switch and do the same procedure

for the right engine.  Both conditioning levers should be in the low idle position.

 

So this essentially helps burn less fuel also? Aside from the taxing issue.

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Even though the King Air is a turbo-prop aircraft,  you can equate the conditioning levers to that of the mixture levers in a piston engine prop aircraft.  There is no real "Leaning" of the fuel mixture but you are reducing the fuel flow.  I will take a quick look at the amount of prop feather that is required at altitude.

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7 minutes ago, charliearon said:

Even though the King Air is a turbo-prop aircraft,  you can equate the conditioning levers to that of the mixture levers in a piston engine prop aircraft.  There is no real "Leaning" of the fuel mixture but you are reducing the fuel flow.  I will take a quick look at the amount of prop feather that is required at altitude.

Yes, please let me know what you find. 

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In the following screenshot I am at FLT300 cruising at 285 knots "Ground Speed" and prop RPM as shown on the dials and engine thrustlever assy.  Fuel flow is 300lbs/hr which should give a fair amount of distance depending on winds aloft.  I had about 2300 lbs of fuel on board at the time of the screenshot, so I have about 7 hrs. of flight time available

 

KingAir.jpg

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12 hours ago, charliearon said:

In the following screenshot I am at FLT300 cruising at 285 knots "Ground Speed" and prop RPM as shown on the dials and engine thrustlever assy.  Fuel flow is 300lbs/hr which should give a fair amount of distance depending on winds aloft.  I had about 2300 lbs of fuel on board at the time of the screenshot, so I have about 7 hrs. of flight time available

 

KingAir.jpg

Thank you so much!

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Actually this is not so representable, Charlie had a backwind of 30kts ( 159KTS IAS x 160% ( 30 x 2%)) =254KTS, with a headwind his consumption would have been more high but the consumption isn't that bad, the real PT6A-60A engine has a powerspecificfuelconsumption off 0.678 and the FSX model only 0.55.

I changed the flight tuning sector a lot to get a more stable flight because the default pitches and rolls a lot even with no wind;

Here is my flight tuning section in the aircraft .cfg

[flight_tuning]
cruise_lift_scalar     = 1.00
parasite_drag_scalar   = 0.9
induced_drag_scalar    = 0.95
elevator_effectiveness = 1.4
aileron_effectiveness  = 1.613
rudder_effectiveness   = 0.79
pitch_stability        = 3.5
roll_stability         = 1.23
yaw_stability          = 1.553
elevator_trim_effectiveness = 0.8
aileron_trim_effectiveness  = 0.853
rudder_trim_effectiveness   = 1.021

Herman

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OK on the condition levers. The King Air is a turboprop or a propeller driven by a jet engine. The condition levers have nothing to do with mixture like you would find in a piston aircraft and the PT6A uses a pneumatic fuel control unit that takes care of all fuel requirements. All the condition levers do is set the flight idle position of the power levers and allow you to cutoff fuel to the engines. In the 350 they set your flight idle N1 speed at 62% at low idle and 70% at high idle. The AFM calls for the condition levers to be in high idle from take-off through landing. 

On the range, this is a turboprop. First all manufacturers give range under the best possible conditions. That is at perfect atmospheric conditions with an airplane lightly loaded and following climb procedures precisely. This is almost never found in the real world. 1. Mother Nature hardly cooperates 2. ATC normally holds turboprops lower than the faster jet traffic so you never get to follow Beech's climb procedure 3. Our job is to move people so we fill up the airplane. All of that changes our range.

The other thing you have to realize is a King Air can either get their fast or fly slower but go further. You absolutely have to fly this airplane by the book to get the range you desire. Upper 20s FL260 to FL290 will get you faster speeds (generally) while low 30s (FL300 to FL350) will get you better range. But, and this is a big but, winds have a huge effect on the King Air. A stiff headwind will kill your range faster than any other element. We shop for winds when flight planning. It really is a matter of burning a few extra pph but getting a lower headwind component.

Also realize that FS is the least expensive sim you can own, that the default aircraft are generally just OK when it comes to flight dynamics and bottom line it is just a sim. Don't expect a Volkswagon to perform like a Porsche. 

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Would be a subject for a nice challenge, who can fly the longest flight with full fuel and default passenger payload ( 2 crew and 4 passengers) and no changes made to the fuelflow or power specific fuel consumption numbers on the default King Air 350?

Herman

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29 minutes ago, electricman said:

Would be a subject for a nice challenge, who can fly the longest flight with full fuel and default passenger payload ( 2 crew and 4 passengers) and no changes made to the fuelflow or power specific fuel consumption numbers on the default King Air 350?

Herman

Go ahead and let us know how it turns out!  My fanny can't last that long in the saddle!:happy:

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Did a flight from KSEA Seattle to Houston TX KIAH and got just to Waco landing on fumes, distance about 1550NM with first half off the flight a tailwind from 60Kts and second half dropping to 20Kts, FL310 following a high altitude flightplan ( not GPS direct ), this is a quit accurate fuel consumption data in the cfg for a default plane.

Herman

 

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