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14

This explanation is given here : The wing of the 777X is based upon the design of the 787’s wing. It has less of the sweep of the 787 but 10% more surface area (increased from 4,702 to 5,562 sq. ft.). The re-shaping has led to a higher lift-to-drag ratio, which(and) in turn increases usable fuel bulk from 320,863 to 350,410 lb. As a result, the type will ...


12

There's a trade-off between saving weight and improving lift-to-drag ratio. In the case of the 77X, the efficiency gain of the improved lift-to-drag ratio of the longer wing outweighs the potential weight saving of the shorter wing. In other words: the drag reduction results in more fuel savings than the weight reduction would. For long-range aircraft, it ...


0

I can not see a comprehensive answer to the first question but will answer the next three Why does fuel consumption decrease with increasing aircraft altitude? Because of an improved ratio of true speed to total drag. See question 2 What is the relation between an airplane's altitude and the drag it is experiencing? With reduced air density more speed is ...


1

There is one possible explanation in the analysis of the airfoil and the airspeed it is flown at. A cambered wing, such as the Davis or the DAE-21, will produce superb lift to drag ratios, but at much lower airspeeds than supercritical wings fly at. The Breuget Equation is as follows: Range = Velocity × Lift/Drag x Specific Impulse × ln(W2/W1) Specific ...


2

The Carnot condition notwithstanding, whether a ramjet actually operates at a higher "hot end" temperature than a turbojet is questionable, as well as whether a comparable percentage of thermal energy in the exhaust stream is converted to kinetic energy. Further, just because there's no turbine, doesn't mean there's nothing in the hot part of the ...


7

They just got this wrong. I have flown F28-1000 and -4000, the F100 and the B767-300. The most feet per nautical mile lost of these with idle power at any given Indicated Air Speed (say 270-280 below 25000 ft) is the F28-1000 (around 475 fpnm) then the F28-4000 at about 425 fpnm, then the F100 at about 350 fpnm and the best is the B767 at about 300-330.The ...


0

For flight time and saving fuel, the density is not relevant. Density is relevant to distance covered if you need a set cross country distance rather than a set time. You would only want to set power to maximum endurance which will be very near best glide CAS, while best true airspeed and ground speeds would change with density the best endurance CAS would ...


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