Before clicking on to an additional page, take into consideration this: fuel thickness renders the difference in between making Point A to Point B for any type of aircraft that flies more than an hour away from home. This makes a difference for any kind of lengthy haul airplane.

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We flew the GV for years discovering that we could do San Francisco to Tokyo non-soptimal even via a headwind, however the rerotate expedition was not always possible. We couldn"t ever before put on a complete fill of fuel in Japan but gallons are gallons, right? As it transforms out, fuel density was the culprit and also nobody knew that until Gulfstream did a research and also released the results in the October 28, 2005 Breakrapid Minutes. As it transforms out, "The aircraft array is identified by fuel weight, not volume," so if your gauges say you have actually less gas, chances are you perform.

If you are planning on flying to the airplane"s maximum range you need to understand fuel thickness, specifically if operating out of Asia.

Our Boeing 747"s had actually a total fuel capacity of 300,000 lbs, which supposed the majority of array. But periodically we ended up via the majority of extra range or a lot less. We didn"t understand also fuel thickness and we must have. To us, density was a puzzle.

Everything right here is from the recommendations presented listed below, through a couple of comments in an different shade.


Fuel Density Defined

Scientific meaning of density: thickness (ρ) of a body is the proportion of its mass (m) to its volume (V). Density of fuel is “the mass of fuel per unit volume”. In some instances the thickness is expressed as a details gravity or relative thickness, in which case it is expressed in multiples of the thickness of some various other traditional product, commonly water or air. Reference: ASTM D1655 specification, Jet A-1 fuel has a thickness of between 775.0 and 840.0 kg/m3. Density ranging from 37 to 51 °C API corrected to 15 °C or 60 °F.

When it comes to fuel, higher density suggests more "bang for the buck." The density is identified by the high quality of the crude offered to produce the fuel and the refining procedure.

Measuring Fuel Density

Fuel density is normally measured via a hydrometer, which is nopoint even more than a glass tube with a weighted bottom that sinks to a level proportional to the density of the liquid. The hydrometer is calibrated against a range used to recognize the thickness for a given temperature.


Figure: Fuel thickness hydrometer, from Fuel Handling Jet Quality and Test Procedure, number 1.8.

Fuel Density versus Weight

Using a fuel density of 6.75 pounds per gallon at 60°F, the complete usable fuel capacity of a G450 is 29,500 lb. (13,380 kg), for a total of 4,370 US gallons (16,542 liters). It is permissible to exceed 29,500 lbs of fuel (because of fuel densities) so lengthy as the maximum ramp and takeoff weights are not exceeded.

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

The variables include:

Aircraft mindset in the time of refueling Wing volume Fuel Quantity Measuring System (FQMS) accuracy Fuel temperature Fuel thickness

Gulfstream conducted a research on this topic when the GV was the queen of the fleet, but the lessons learned use to the G450 too. For the sake of the study, keep in mind a GV"s publimelted fuel capacity is 41,300 lbs.

Impact Comparisons

Aircraft Attitude Impact on Fuel Capacity

The GV"s fuel capacity was designed through the aircraft perspective at 1-1/2° nose down, however the maximum variation as a result of ramp attitude was uncovered to be just 22 gallons / 148 pounds.

Wing Volume Impact on Fuel Capacity

Aircraft considering that GV sn 529 have been tested for complete volume capacity and also uncovered "satismanufacturing facility."

FQMS Accuracy Impact on Fuel Capacity

The design specification of the FQMS is ±300 lbs. Typical performance is ±200 lbs. Spot checks have been found "satisfactory."

Fuel Temperature Impact on Fuel Capacity

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

Using these numbers, a G450"s published capacity of 29,500 lbs (4,370 US Gallons) at 60°F will drop to 28,900 lbs at 90°F.

Fuel Density Impact on Fuel Capacity

Fuel thickness has the greatest impact on fuel capacity. A GV"s maximum fuel volume is 6,118 USG, this does not change. Variation in human being fuel thickness deserve to reason the GV"s maximum fuel capacity to readjust even more than 5,000 lbs.

Jet-A fuel thickness boundaries are established by the Amerideserve to Society for Testing and Materials (ASTM) Specification D1655. At 60°F the thickness boundaries are from 6.46 to 6.99 lbs/gallon.

In a G450, this amounts to a variety of:

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

A variation of 2,316 lbs.

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Surveys disclose this trend:


Example Fuel Density Charts

Michael McLeod has gone with the work on a few aircraft to carry out fuel thickness charts.