Falcon 900EX EASy / Falcon 900LX

[lelac]

Hello all, I am looking for more info on the REAL range for those aircrafts. I have lots of exeperience on the Falcon 2000 / 2000LX, and I know that the range advertised by Dassault is questionable. So, for those with hands on experience, any comments? Real flights done? Thanks! LeLac

[The BFG]

Hi Lelac,
We had a new 900 EASy for a while (great aircraft)! before our 7X. Looking back in my logbook, we did New Delhi (VIDP) to Luton (EGGW), and I've logged 9:55 block with 9:35 instrument time. We must have landed with good reserves, because I wouLd have remembered any anal twitching re fuel or lack off! Do remember a lot of anal activity on that trip though, but that was purely gastric! Phewee!!! (3 crew, 4 pax btw).
Regards,
Big-friendly

[Mizuno boy]

9:41 actual air time, 2000 pounds remaining at engine shutdown. Mach .77 - .78 in a 900Exy

[lelac]

Thanks for your replies BFG and Mizuno!
I was looking for GIG (Rio de Janeiro Intl.)- TEB.
Great Circle it's 4,177nm / Airways computed it's 4350 nm (~10:20 flying LRC).
Taking into account the usual early descents for the arrival, I think it's quite on the limit...
So, according to (unrealistic) Dassault, the aircraft is 4,750 nm with winglets installed and a normal BOW. How come their advertisement is SOOOO stretched???

[Amadis of Gaul]

Because marketing.

[The BFG]

Hi Lelac. Rio-KTEB won't work. I've done this several times and always had to stop in Manaus. It is a good servic there though, as they know you just want in and out! The good thing on the way South though is you can fly to Santos Dumont (domestic) rather than the International which is a nightmare. But then you probably know all this!!

[lelac]

Hi Lelac. Rio-KTEB won't work. I've done this several times and always had to stop in Manaus. It is a good servic there though, as they know you just want in and out! The good thing on the way South though is you can fly to Santos Dumont (domestic) rather than the International which is a nightmare. But then you probably know all this!!
:ok::ok::ok:

[lelac]

Guys, again many thanks for info; Another question: taking into account different areas of the world, different temperatures, fuel specific density, etc... Whats the average MAXIMUM FUEL TANK you, with hands on experience, have seen? Rgds LeLac

[CL300]

Ha , the old discussion about volume and weight...Which is completely irrelevant for range...

Just think of one thing : what does your engines burn ? Volume or Weight ?

[Mizuno boy]

Anywhere from 22,100 lbs on a cold day in Alaska to 19,800 lbs on a very warm day in Europe. Typically if you add fuel used on the FMS and Fuel remaining on the gauges you show very close to 21,000 lbs at start up.

Cheers

MB

[His dudeness]

what does your engines burn ? Volume or Weight ?

Fuel ?


Sorry, couldn't resist.

[lelac]

Ha , the old discussion about volume and weight...Which is completely irrelevant for range...

Just think of one thing : what does your engines burn ? Volume or Weight ?

Hi CL300! Yep, the old discussion... But that's exactly the problem: engines burn weight. But fuel tank is constrained by volume.

With the SG of the fuel you get in east asia you will be weelllllll below your usual full fuel load.

On top of that, some specific aircraft models are known to have issues with the FQMC (fuel quantity mangmt. computer - or whatever its called by the OEM).

That's why I wanted to know from actual F900 operators.

[galaxy flyer]

Well, yes and no on specific gravity issue. I've departed 800-900 pounds under the FPL fuel load due to the high level sensors being reached and fueling stopped many times. Alwas landed about at FPL landing fuel. I know the details, but it works out.

GF

[CL300]

The indication is weight, but through the engines nozzles goes volume. Therefore as long as the tanks are full ( volume) irrespective of the weight being shown, you will get the range.
Now, everyone is "happier" when the weight is "higher" on cold fuel, leading to the view of higher range, alas...there is no such thing, like GF wrote above, at the end of the day after 10 hours at minus 50 ( to -70) you will get your fuel "back".
Some probes are compensated for temperatures some are not, i would believe that the 8X and 5X are, not on the F2TH or GLEX early generations AFAIK

[wondering]

AFAIK the Brayton cycle represents the operation of a gas turbine engine. It uses units of mass in its formulas. The same is true for thrust equations. In any chemical reaction units of mass react with each other not volumes.

[lelac]

The indication is weight, but through the engines nozzles goes volume. Therefore as long as the tanks are full ( volume) irrespective of the weight being shown, you will get the range.
Now, everyone is "happier" when the weight is "higher" on cold fuel, leading to the view of higher range, alas...there is no such thing, like GF wrote above, at the end of the day after 10 hours at minus 50 ( to -70) you will get your fuel "back".
Some probes are compensated for temperatures some are not, i would believe that the 8X and 5X are, not on the F2TH or GLEX early generations AFAIK

CL300, I hope you don't fly a long range aircraft. Or at least never had to top up your tanks. If you do, I recommend you some reading...

What you mentioned above is for TEMPERATURE variations only! DENSITY (determined by the quality of the crude used to produce the fuel and the refining process) plays a much more important role.
Jet-A fuel density limits are established by the American Society for Testing and Materials (ASTM) Specification D1655. At 60°F the density limits are from 6.46 to 6.99 lbs/gallon.

If I may recommend a starting point for your reading, what about that study by Gulfstream?

GV/G500/G550 (ATA 28): Fuel Density Variations

A GV flight crew reported experiencing the inability to fully fuel their aircraft during a
fueling stop. During fueling, the Fuel Quantity Monitoring System (FQMS) indicated a
maximum fuel load of 39,900 lb. The flight crew also indicated that the ambient and wing fuel
tank temperatures were low.
The crew further attempted to fill the wing by pulling the left- and right-fueling shutoff
circuit breakers, parking the aircraft nose down, shaking the wing, and eventually over wing
fueling. The over wing fueling resulted in only an additional 15 gallons of fuel.
The maximum volumetric fuel capacity of the GV aircraft is nominally 6,100 U.S. gallons
(USG). Based on a fuel temperature of 60°F and a typical fuel density of 6.767 lb./USG, the
maximum fuel weight is 41,300 lb. (Note: The aircraft range is determined by fuel weight, not
volume.)
Variations in fuel density and expansion at elevated temperatures, especially when fuel is
stored above ground in hot climates, will result in an inability to obtain the nominal maximum
fuel weight of 41,300 lb. at 6,100 USG.
Per specifications as listed in the AFM, Section 1, “Engine Fuel Grades,” manufactured fuel
density at a constant temperature can vary to the acceptable lower limits of 6.47 lb./USG at
60°F. The GV FQMS includes a densitometer and will automatically compensate for density
effects and correctly display the actual fuel weight. At the lower limit of 6.47 lb./USG at 60°F,
the FQMS would indicate a full fuel reading of approximately 39,400 lb. at 6,100 USG.
Fuel temperatures greater than 60°F also limit the nominal maximum fuel weight due to
thermal expansion of the fuel. For each additional 10 degrees in fuel temperature, the
maximum fuel weight is reduced by approximately 200 lb. at 6,100 USG.
The following table, generated by the Gulfstream ECS Power Plant group, illustrates fuel
density variations as affected by temperature and the acceptable upper and lower limits at
constant temperature. The source data used in the table is compiled from the Coordinated
Research Counsel (CRC) Report 530 – Aviation Fuel Properties, and the American Society for
Testing & Materials ASTM D1655 – Standard Specification for Aviation Turbine Fuels. CRC
Report 530 contributors include participation from the major petroleum companies, and
sustaining members include the American Petroleum Institute (API) and the Society of
Automotive Engineers (SAE).

[CL300]

OK I rephrase, and Gulfstream is writing it the same way.
For A specific fuel density, temperature is the limiting factor, and Gulfstream chose to limit the amount of fuel in the tanks to permit expansion. ( not Dassault on the F2TH), as a consequence for the same "quality" of fuel, the range will be the same for the volume loaded.
As far as thermodynamic is concerned, yes you are right in a closed system ( Brayton cycle), which is NOT the case as heat exchange occurs between the fuel and the exterior.

The engine fuel metering are sending volume of fuel through the nozzles, not weight of fuel, the indicated Lbs/hrs is a computed information based on standard value ( may be today the FQMC are smart enough to read the SG and such and give a better insight to the crews.

I only flew the G 2, long time ago, and thanks for the reading..

[lelac]

OK I rephrase, and Gulfstream is writing it the same way.
For A specific fuel density, temperature is the limiting factor, and Gulfstream chose to limit the amount of fuel in the tanks to permit expansion. ( not Dassault on the F2TH), as a consequence for the same "quality" of fuel, the range will be the same for the volume loaded.
As far as thermodynamic is concerned, yes you are right in a closed system ( Brayton cycle), which is NOT the case as heat exchange occurs between the fuel and the exterior.

The engine fuel metering are sending volume of fuel through the nozzles, not weight of fuel, the indicated Lbs/hrs is a computed information based on standard value ( may be today the FQMC are smart enough to read the SG and such and give a better insight to the crews.

I only flew the G 2, long time ago, and thanks for the reading..

:ok::ok::ok:

[clivewatson]

We regularly got 4400nm air miles out of the 900LX. Longest flight I recall was 10:50 (FSIA to LSZH) landing with circa 1250lbs and airmiles of 4650nm. Got a number of pics of the fuel page after landing to confirm air miles, times and fuel remaining. Achieved same out of 900EX by flying exactly according to book, but climbing (albeit a bit slowly) a little sooner than the book.

Kept a strict log of perf data and can confirm that the aircraft (ours) did exactly what it said on the tin, but to be honest I wanted the alternate to be pretty damn close.

[Bizjetlover]

Seychelles-Zurich is 4000 nm, sure it was 4600nm?

[clivewatson]

Track distance alone is meaningless. That's why I quoted air miles which is what the thread starter is inquiring about.

[Mach Tuck]

The indication is weight, but through the engines nozzles goes volume. Therefore as long as the tanks are full (volume) irrespective of the weight being shown, you will get the range.

You cannot escape the fact that the calorific value of fuel is directly proportional to its mass, not its volume. A pound of fuel generates n units of heat (thrust) regardless of its S.G. and temperature but the volume of that pound varies with both these factors.

It follows that the total heat generated by a tankfull of 0.79 S.G. fuel is only 97.5% of that of the same tankfull of 0.81 S.G. fuel. Engine performance is unaffected; fuel may well be metered by volume but the lower the S.G. the more volume the FADEC demands to achieve the required thrust (2.5% more, using this example) and that reduces range by an equivalent amount.

[CL300]

Except that your fuel goes into the nozzles at a constant temperature ( heat exchanger ) negating the "effect" of temperature.
This is why it does not matter much, and everyone is "creating" fuel by the end of cruise.

[lelac]

You cannot escape the fact that the calorific value of fuel is directly proportional to its mass, not its volume. A pound of fuel generates n units of heat (thrust) regardless of its S.G. and temperature but the volume of that pound varies with both these factors.
It follows that the total heat generated by a tankfull of 0.79 S.G. fuel is only 97.5% of that of the same tankfull of 0.81 S.G. fuel. Engine performance is unaffected; fuel may well be metered by volume but the lower the S.G. the more volume the FADEC demands to achieve the required thrust (2.5% more, using this example) and that reduces range by an equivalent amount.

:D:D:D:D:D:D:D:D:D:D:D:D:D:D

[Mach Tuck]

Except that your fuel goes into the nozzles at a constant temperature ( heat exchanger ) negating the "effect" of temperature.
This is why it does not matter much, and everyone is "creating" fuel by the end of cruise.

Now that you've got me started...

The temperature of the fuel at the nozzle is totally irrelevant: the calorific value of a pound of fuel at 100C at the nozzle is exactly the same as it is at -10C in the tank. It is the temperature of the fuel at delivery to the tank that is important.

The volume of a unit mass of fuel changes by about 0.1% per 1C temperature change. A 1,000 litre tank will hold 800kg of 0.80 S.G. fuel at 15C. Because of expansion the same tank would hold only 784kg of fuel if it were delivered at 35C - so a range reduction of 2%. Conversely, 816kg of could be loaded if the delivery temperature was -5C giving an increase in range of 2%.

Now combine this with the discussion in my previous post - a tankfull of 0.79 S.G. fuel delivered at 30C will give 4.5% less range than that tankfull of 0.81 S.G. fuel delivered at 10C.

The 'creation' of fuel in flight is down to inadequacies in the fuel measuring system.

Lastly, be it a Gulfstream or a Falcon, it is a certification requirement that fuel expansion up to 2% (equivalent to heating it by 20C after delivery) will be accommodated by tank design.

[lelac]

Not to mention the quality of the crude used to produce the fuel and the refining process. Irrespective of delivery temperature, the SG of a Jet A delivered in east asia will NEVER get even close to the one delivered in Canada for instance...
That's why my ORIGINAL question was about what quantity the Falcon 900 operators could expect normally...

[Mach Tuck]

Sorry Lelac, I can't help you there. It is some 15 years since I flew a 900 and apart from that it was a cracking aircraft to fly I don't remember much about the detail. My contribution was merely to address the notion that a full tank of fuel would 'get you there' regardless of other factors.

[CL300]

Quantity goes to the float switches when full, then you will have the above answer that will go into computations to tell you that you will be heavier in winter and lighter in summer. And one guy telling you that he flies 4650 AIR MILES with its bird....
Dassault planes are flying like the book if they are flown like the book says.

QUALITY of fuel is far more important than its temperature, and (except when bags or pax were SUPER heavy, and not weighted) I flew the 2000, the 900 and the GLEX with their numbers on OFP, even if leaving the ground with 1000 to 2000 less than indicated required, upon arrival, numbers are matching.

But i do agree with everything written above... in a perfect world of entropy and exergy..

[Lucky8888]

Dassault planes are flying like the book if they are flown like the book says.


Exactly correct with the 900LX I fly.