james42

Falcon 50 Fuel Planning

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Hi everyone, I was wondering what method people have been using to find out how much they will need for a flight. I did a flight yesterday and landed with less than 150 pounds of fuel remaining. Are there any fuel planning/altitude charts freely available online? Thanks in advance for your answers.     

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I use   www.fltplan.com  for all my flights.   If you're willing to put in the time to learn the site and how to use it, I feel this answer your question.  Once you are setting up your aircraft just choose the FA50 EX for your aircraft and the fuel burns plus fuel planning will be pretty close to what you need.   Obviously this site is a lot more than just fuel planning, but you can explore it and see if it fills your needs.

I am attaching an image of a recent flight plan I completed so you can see all the data this site can provide you.  (hope the attachment below works ) :rolleyes:

Capture.png

 

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Conservative (i.e. safe) ballpark figures that will work for a ~450 knot (true) cruise: 2800 first hour + 2400 second hour + 2000/hr afterward. Don't forget to add a reserve on top of this (I'm partial to 60 minutes, or 2000 lbs in this case).

e.g. for a 4 hour flight: 2800 (hour 1) + 2400 (hour 2) + 2000 * 2 (hours 3 and 4) + 2000 (reserve) = 11200 lbs.

Regardless of method, the important thing is to remember that fuel planning doesn't end with preflight; it continues until you're back on the ground. Think of fuel in terms of time (and not distance or weight or anything else), and start the counter once you hit your first waypoint. If turns out that you're significantly behind schedule (over the course of the flight) and will therefore have less time to loiter about your destination than planned, that's when you want to start thinking about a diversion. You should never land with less than your minimum reserve (which may or may not be less than the reserve mentioned above)...it's only the airport that might change. 🙂

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Posted (edited)
4 hours ago, jws527 said:

Conservative (i.e. safe) ballpark figures that will work for a ~450 knot (true) cruise: 2800 first hour + 2400 second hour + 2000/hr afterward. Don't forget to add a reserve on top of this (I'm partial to 60 minutes, or 2000 lbs in this case).

e.g. for a 4 hour flight: 2800 (hour 1) + 2400 (hour 2) + 2000 * 2 (hours 3 and 4) + 2000 (reserve) = 11200 lbs.

Regardless of method, the important thing is to remember that fuel planning doesn't end with preflight; it continues until you're back on the ground. Think of fuel in terms of time (and not distance or weight or anything else), and start the counter once you hit your first waypoint. If turns out that you're significantly behind schedule (over the course of the flight) and will therefore have less time to loiter about your destination than planned, that's when you want to start thinking about a diversion. You should never land with less than your minimum reserve (which may or may not be less than the reserve mentioned above)...it's only the airport that might change. 🙂

Interesting, thanks.

If you apply this method to the 1:30hr trip posted above by vcarlo you get

fuel = 2800 for 1st hr + 1/2(2400) for half of 2nd hr + 1500 for 45 min reserve = 5500lbs which is pretty close to the FltPlan value of 5266.  And since the FltPlan calculations above assume about a  64 kt headwind, this figure is indeed conservative.

If nothing else, this is a good, quick way to run a double check and catch entry errors on more involved fuel calculations such as when using the FltPlan site, which I have used and like.

Al

Edited by ark

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Thanks for the advice guys, some really helpful stuff here. I have one more question regarding fueling. What is the correct way to distribute the fuel in the tanks? For example, in vcarlo's post above the minimum fuel required for this flight would be 5,266ibs. How would i go about distributing this figure in the tanks? Fill the center tank first then the wings or wings first then the center?  Or is there a way of entering a specific fuel number via the payload manager and fueling the aircraft that way? 

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48 minutes ago, james42 said:

Thanks for the advice guys, some really helpful stuff here. I have one more question regarding fueling. What is the correct way to distribute the fuel in the tanks? For example, in vcarlo's post above the minimum fuel required for this flight would be 5,266ibs. How would i go about distributing this figure in the tanks? Fill the center tank first then the wings or wings first then the center?  Or is there a way of entering a specific fuel number via the payload manager and fueling the aircraft that way? 

In a Falcon, each tank supplies only one engine in normal operation. Left engine fed by the left wing and feeder, center engine by the center tank and feeder, and right engine by the right wing and feeder. 

You should not attempt to put a specific amount in any given tank. For any given total load of fuel, there is a specific starting ratio of fuel in a main tank vs. the associated feeder tank. 

This is required for keeping the aircraft center of gravity within limits. That is the reason why the center main tank is smaller than the main wing tanks, and the center feeder tank is larger than the wing feeders.

In the real aircraft, the crew will calculate the amount to be loaded in each tank using planning charts, and the distribution per tank will be broken down on the refueling order given to the fuel truck operator.

In the FSW aircraft, you have a choice of three preset fuel loads, and the system will correctly split the distribution between the main tanks and respective feeders for each preselected amount. You should not attempt to manually override that by using the default FSX/P3D fueling menu. Always use the FSW refueling pop-up menu.

On a very short flight, using the presets might give you more fuel than you really need even at the “light” load, but it won’t impact perfomance that much.

 

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Jim -- that's super info above on the fueling of the Falcon.

Very interesting -- thanks!

I'm curious, in the real a/c, how is fuel directed to the appropriate tanks to meet the requirements you have outlined above? Are there controls at the fueling point that allow fuel to be directed to each of the six tanks, or just the 3 wing tanks  and then the feeders fill based on their valve float system.

Al

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1 minute ago, ark said:

Jim -- that's super info above on the fueling of the Falcon.

Very interesting -- thanks!

I'm curious, in the real a/c, how is fuel directed to the appropriate tanks to meet the requirements you have outlined above? Are there controls at the fueling point that allow fuel to be directed to each of the six tanks, or just the 3 wing tanks  and then the feeders fill based on their valve float system.

Al

On the Falcon 50 refueling panel, there are toggle switches that open and close the refueling valves for the various tanks, so the refueler can put the requested amount in each tank. The crew has to do the paperwork and calculations ahead of time to determine how much to put in each. In the old days, thus would require using paper charts and graphs from the aircraft performance manual as part of the initial weight and balance calculations. Nowadays Falcon 50 pilots probably use an iPad app to do all that. 

The calculations for the total load for each tank will also take into account how much fuel was already in the tanks from the previous flight.

It is much easier (for the pilots and fuel truck operator) on a Falcon 900. The 900 does not have separate feeder tanks, and the center tank is split into three discrete tanks, (forward center and aft). When the external refueling panel is activated the aircraft fuel computer comes online, and automatically controls the distribution. The fuel truck operator only has to preselect the total load, and the computer automatically opens and closes valves during refueling to insure that the correct amount goes into each tank.

On the 900, the aft center tank is much smaller than the other two, and only comes into play with a full fuel “top off” load. Normally it is kept empty. During flight, the fuel is burned from the three individual tanks in the center tank group in the proper sequence to keep the CG within limits.

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7 minutes ago, JRBarrett said:

On the Falcon 50 refueling panel, there are toggle switches that open and close the refueling valves for the various tanks, so the refueler can put the requested amount in each tank.

 I can see why the fuel gauges in the Falcon 50 read all six tanks. I think it would be important to check the tanks were filled correctly for weight and balance reasons, as well a total load, before taking off.

Thanks,

Al

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16 minutes ago, ark said:

 I can see why the fuel gauges in the Falcon 50 read all six tanks. I think it would be important to check the tanks were filled correctly for weight and balance reasons, as well a total load, before taking off.

Thanks,

Al

I should add that in the case of filling the feeder tanks, the refueling operator only has the option of filling them to “HI” or “LO” level, selected by a toggle switch. (There is an upper and lower fuel sensor in each tank). In “HI”, they are fueled to full. In “LO” setting, they stop filling when fuel reaches the lower sensor.

There are separate toggle switches to open or close the fuel inlet valves on the three main tanks.

In the case of a top-off to full fuel, each wing tank fuel inlet valve will automatically close when the tank is full. 

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What an interesting insight to what is actually a rather complex little airplane. Thanks for all your replies.

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11 hours ago, james42 said:

What an interesting insight to what is actually a rather complex little airplane. Thanks for all your replies.

Another feature which is somewhat unique to Dassault aircraft is the fact that the fuel tanks are not vented to the external atmosphere. In most aircraft, vents are required so that external air can enter the tank as fuel is drawn out.

On Falcons, the tanks are internally pressurized to about 3 PSI by a tap-off from the engine bleed air system. The positive air pressure helps keep fuel flowing in case there is a boost pump failure, and helps prevent the pumps from cavitating at higher altitudes. It also helps to prevent external moisture from getting into the tanks in flight.

When the aircraft is refueled after landing, the tanks are first de-pressurized by moving a lever that covers the cap on the single-point refueling port. When the lever is moved aside, it electrically opens vents valves, and you will hear a loud "whoosh" as the tank air pressure is released from three vents on the lower fuselage. 

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12 hours ago, james42 said:

What an interesting insight to what is actually a rather complex little airplane. Thanks for all your replies.

+1 Thanks a lot

Pascal

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Posted (edited)

Based on tech advice and the other feedback received on the flap sounds, FSW has decided in the interest of realism to leave them as they are -- silent.

Al

Edited by ark
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On 3/4/2019 at 3:33 PM, JRBarrett said:

When the aircraft is refueled after landing, the tanks are first de-pressurized by moving a lever that covers the cap on the single-point refueling port. When the lever is moved aside, it electrically opens vents valves, and you will hear a loud "whoosh" as the tank air pressure is released from three vents on the lower fuselage. 

When this happens, does the air around the aircraft smell like jet fuel?  Or is it not enough air involved to "fume-up" the area?

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3 minutes ago, Mace said:

When this happens, does the air around the aircraft smell like jet fuel?  Or is it not enough air involved to "fume-up" the area?

You definitely don’t want to do it inside a closed hangar! Yes, if the air is calm, you’ll smell a bit of fuel vapor for a few moments - mainly near the back of the aircraft.

Pressuruzed fuel tanks are not common on civilian aircraft. It comes from Dassault’s heritage of building military fighters before they entered the civil business jet market in the late 1960’s. Pressurized tanks are quite common on fighters.

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