punkalouver
14th Sep 2005, 03:12
Quote from a recent 'Professional pilot' article.
While not a quality issue, longhaul operators should be aware of differences in refining methods around the world that could affect range capability. AIG Dir Aviation Franklin Davis says that his Bombardier Global Express has reduced full tank range when coming out of Asia, as specific gravity of the local fuel differs from what it is stateside. "fuel is refined differently around the world. There are different types of Jet A. Volume, based on the viscosity of the fuel can vary, and you might find specific gravity differences of 5-10%."
Quote from 'Business and Commercial Aviation' article.
Given a manual volume shutoff system(float valves), the fuel system on an airplane shuts off at the same liquid level all the time. If you could look in the wing of a full Global Express, indicating 14,700 pounds of warm fuel or a fuel refined with a lower specific gravity, there would be just as much liquid in there as if it shut off by full volume, and indicated 15,000 pounds in a cooler climate or somewhere where the refined densities are a little higher.
Jet engine efficiencies depend on temperature change from intake. This less dense fuel while still refined within the specifications of Jet-A, is more burnable than more dense kerosenes. The less dense Jet-A's produce more heat per volume unit and as a result require less units to do the same job. Also, since you actually can weigh many hundreds or even thousands, of pounds less with less-dense jet-A than Kerosene at any given time in the trip, you are able to achieve the same cruise parameters with less energy. I have consistently flown longer, with more fuel remaining at the end of the trip, when I started with full tanks of less-dense fuel.
The point of all this is that if you have a flight plan that indicates a doable trip, a lower indication of fuel when the tanks are full volume wise should not affect that flight plan.
Do these two articles contradict each other?
Is this something that is taken into consideration by anybody out there?
While not a quality issue, longhaul operators should be aware of differences in refining methods around the world that could affect range capability. AIG Dir Aviation Franklin Davis says that his Bombardier Global Express has reduced full tank range when coming out of Asia, as specific gravity of the local fuel differs from what it is stateside. "fuel is refined differently around the world. There are different types of Jet A. Volume, based on the viscosity of the fuel can vary, and you might find specific gravity differences of 5-10%."
Quote from 'Business and Commercial Aviation' article.
Given a manual volume shutoff system(float valves), the fuel system on an airplane shuts off at the same liquid level all the time. If you could look in the wing of a full Global Express, indicating 14,700 pounds of warm fuel or a fuel refined with a lower specific gravity, there would be just as much liquid in there as if it shut off by full volume, and indicated 15,000 pounds in a cooler climate or somewhere where the refined densities are a little higher.
Jet engine efficiencies depend on temperature change from intake. This less dense fuel while still refined within the specifications of Jet-A, is more burnable than more dense kerosenes. The less dense Jet-A's produce more heat per volume unit and as a result require less units to do the same job. Also, since you actually can weigh many hundreds or even thousands, of pounds less with less-dense jet-A than Kerosene at any given time in the trip, you are able to achieve the same cruise parameters with less energy. I have consistently flown longer, with more fuel remaining at the end of the trip, when I started with full tanks of less-dense fuel.
The point of all this is that if you have a flight plan that indicates a doable trip, a lower indication of fuel when the tanks are full volume wise should not affect that flight plan.
Do these two articles contradict each other?
Is this something that is taken into consideration by anybody out there?