Before clicking on to an additional page, consider this: fuel thickness makes the difference in between making suggest A to suggest B for any airplane that flies more than one hour far from home. This provides a difference for any kind of long to draw airplane.

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We flew the GV because that years learning that we might do san Francisco come Tokyo non-stop also with a headwind, however the return expedition was not always possible. We couldn"t ever put on a full load of fuel in Japan but gallons room gallons, right? as it transforms out, fuel thickness was the culprit and nobody knew that until Gulfstream go a study and also released the outcomes in the October 28, 2022 Breakfast Minutes. As it transforms out, "The aircraft range is figured out by fuel weight, not volume," so if her gauges say you have actually less gas, opportunities are girlfriend do.

If you room planning on paris to the airplane"s maximum range you require to recognize fuel density, particularly if operating out of Asia.

Our Boeing 747"s had a complete fuel capacity of 300,000 lbs, which intended a many range. But sometimes we ended up through a lot of extra variety or a lot less. We didn"t know fuel density and also we must have. To us, density was a puzzle.

Everything below is from the references shown below, with a couple of comments in an alternating color.


Fuel density Defined

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

When it concerns fuel, greater density way more "bang for the buck." The density is figured out by the high quality of the crude provided to create the fuel and the refining process.

Measuring Fuel Density

Fuel density is typically measured v a hydrometer, which is nothing much more than a glass tube with a load bottom that sinks to a level proportional to the thickness of the liquid. The hydrometer is calibrated against a scale offered to determine the thickness for a provided temperature.


Figure: Fuel density hydrometer, from Fuel handling Jet Quality and Test Procedure, number 1.8.

Fuel density versus Weight

Using a fuel density of 6.75 pounds every gallon at 60°F, the complete usable fuel volume of a G450 is 29,500 lb. (13,380 kg), for a complete of 4,370 united state gallons (16,542 liters). That is permissible to exceed 29,500 lbs of fuel (due to fuel densities) so long as the best ramp and takeoff weights space not exceeded.

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

The variables include:

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

Gulfstream carried out a study on this subject when the GV was the queen that the fleet, but the great learned use to the G450 together well. For the services of the study, save in mental a GV"s released fuel volume is 41,300 lbs.

Impact Comparisons

plane Attitude influence on Fuel capacity

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

wing Volume impact on Fuel volume

Aircraft due to the fact that GV sn 529 have actually been experiment for full volume capacity and found "satisfactory."

FQMS Accuracy impact on Fuel capacity

The style specification the the FQMS is ±300 lbs. Typical performance is ±200 lbs. Spot checks have actually been discovered "satisfactory."

Fuel Temperature impact on Fuel capacity

The Gulfstream GV study revealed that each 10°F increase in fuel temperature diminished the GV"s fuel volume by 200 lbs. The variation in between -20°C and also +50°C, because that example, deserve to be nearly 1,400 lbs.

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

Fuel Density influence on Fuel capacity

Fuel thickness has the greatest affect on fuel capacity. A GV"s preferably fuel volume is 6,118 USG, this does no change. Variation in people fuel density can reason the GV"s best fuel volume to change much more than 5,000 lbs.

Jet-A fuel density boundaries are established by the American society for Testing and Materials (ASTM) Specification D1655. In ~ 60°F the density limits are native 6.46 come 6.99 lbs/gallon.

In a G450, this equals a range of:

28,230 lbs at 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:


Example Fuel density Charts

Michael McLeod has actually gone with the work-related on a couple of aircraft to administer fuel density charts.