Before clicking on to one more page, think about this: fuel thickness makes the difference between making suggest A to suggest B because that any plane that flies much more than one hour far from home. This makes a distinction for any type of long haul airplane.

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We flew the GV because that years discovering that we could do mountain Francisco come Tokyo non-stop even with a headwind, but the return pilgrimage was not always possible. Us couldn"t ever before put top top a full load of fuel in Japan yet gallons space gallons, right? together it transforms out, fuel thickness was the culprit and nobody knew that till Gulfstream walk a study and also released the results in the October 28, 2005 Breakfast Minutes. As it transforms out, "The aircraft variety is determined by fuel weight, not volume," for this reason if your gauges speak you have less gas, opportunities are girlfriend do.

If you room planning on paris to the airplane"s maximum range you need to know fuel density, particularly if operation out the Asia.

Our Boeing 747"s had a complete fuel volume of 300,000 lbs, which meant a many range. But sometimes we ended up v a many extra selection or a many less. We didn"t understand fuel density and we have to have. To us, density was a puzzle.

Everything right here is native the references displayed below, v a couple of comments in an alternating color.


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Fuel density Defined

Scientific definition of density: thickness (ρ) that a body is the ratio of its mass (m) come its volume (V). Thickness of fuel is “the massive of fuel every unit volume”. In some cases the density is expressed together a certain gravity or family member density, in which case it is expressed in multiples that the thickness of some various other standard material, generally water or air. Reference: ASTM D1655 specification, Jet A-1 fuel has actually a density of between 775.0 and 840.0 kg/m3. Density ranging native 37 to 51 °C API corrected to 15 °C or 60 °F.

When it concerns fuel, greater density means more "bang because that the buck." The density is identified by the top quality of the crude used to create the fuel and also the refining process.

Measuring Fuel Density

Fuel thickness is normally measured with a hydrometer, which is nothing an ext than a glass tube through a weighted bottom the sinks to a level proportional come the density of the liquid. The hydrometer is calibrated against a scale supplied to identify the thickness for a provided temperature.


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Figure: Fuel thickness hydrometer, from Fuel taking care of Jet Quality and also Test Procedure, number 1.8.


Fuel density versus Weight

Using a fuel thickness of 6.75 pounds every gallon in ~ 60°F, the full usable fuel volume of a G450 is 29,500 lb. (13,380 kg), for a total of 4,370 us gallons (16,542 liters). That is permissible come exceed 29,500 lbs of fuel (due to fuel densities) so long as the maximum ramp and also takeoff weights room not exceeded.

All that being said, why is it the you cannot always get 29,500 lbs or 4,370 united state gallons on the airplane?

The variables include:

Aircraft attitude during refueling wing volume Fuel amount Measuring system (FQMS) accuracy Fuel temperature Fuel density

Gulfstream carried out a research on this subject when the GV to be the queen of the fleet, but the lessons learned apply to the G450 together well. For the services of the study, save in mental a GV"s published fuel capacity is 41,300 lbs.

Impact Comparisons

plane Attitude impact on Fuel capacity

The GV"s fuel capacity was designed through the aircraft mindset at 1-1/2° sleep down, however the maximum variation because of ramp mindset was discovered to be only 22 gallons / 148 pounds.

wing Volume affect on Fuel capacity

Aircraft because GV sn 529 have been experiment for complete volume capacity and found "satisfactory."

FQMS Accuracy influence on Fuel volume

The design specification of the FQMS is ±300 lbs. Common performance is ±200 lbs. Point out checks have actually been discovered "satisfactory."

Fuel Temperature influence on Fuel capacity

The Gulfstream GV examine revealed that each 10°F increase in fuel temperature decreased the GV"s fuel capacity by 200 lbs. The variation between -20°C and also +50°C, for example, deserve to be practically 1,400 lbs.

Using this numbers, a G450"s published capacity the 29,500 lbs (4,370 united state Gallons) at 60°F will drop come 28,900 lbs at 90°F.

Fuel Density influence on Fuel capacity

Fuel density has the greatest affect on fuel capacity. A GV"s best fuel volume is 6,118 USG, this does not change. Variation in human being fuel density can reason the GV"s best fuel capacity to change much more than 5,000 lbs.

Jet-A fuel density boundaries are established by the American culture for Testing and also Materials (ASTM) Specification D1655. At 60°F the density boundaries are indigenous 6.46 come 6.99 lbs/gallon.

In a G450, this amounts to a variety of:

28,230 lbs in ~ 6.46 lbs/gallon 30,546 lbs at 6.99 lbs/gallon

A sport of 2,316 lbs.

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Surveys reveal this trend:


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Example Fuel density Charts

Michael McLeod has actually gone with the occupational on a few aircraft to administer fuel thickness charts.