# Tag Info

11

what is causing the "corners" that we see at the following points? Compressibility. Close to Mach 1 the lift curve slope increases according to the Prandtl-Glauert rule with the factor $\frac{1}{\sqrt{1-Ma^2}}$. Since the X-axis shows indicated speed, the Mach 1 point moves left with increasing altitude. Technically, those corners should also be ...

8

Alternate Take-off is a reduced power option feature, similar to flex thrust on turbofans. The aircraft manufacturer will provide performance data applicable to the reduced power setting that can be used when circumstances permit. It's all about reducing wear and tear by not running the engine as hard if it's not essential. The Max Continuous power setting ...

5

As an airplane approaches Mach 1, all pressure changes grow with the Prandtl-Glauert factor of $\frac{1}{\sqrt{1-Ma^2}}$. Therefore, the lift curve slope increases so the wing produces more lift at the same angle of attack and dynamic pressure the closer its Mach number is to 1. On wings with thicker airfoils and higher aspect ratio the maximum lift ...

5

The amount of time and manpower required to remove empty seats before a flight, transport them to the plane's next destination (presumably on another aircraft), then reinstall necessary seats for the next flight with 450 passengers (instead of this flight's 300 pax) would far exceed any potential cost savings of removing them for the flight. (Oh, don't ...

5

Plain and simple, to meet current market requirements, Airbus can do pretty much nothing to make the 380 more "current". The technical improvements suggested do nothing to change the fact that the 380 is too big, that is, it has too many seats, thus not allowing enough flexibility in this market situation. In addition to not addressing the main ...

4

Well, if all you care about is the fan performance by itself, then you've pretty much got it. Maximize the component cycle efficiency and maximize the propulsive efficiency and that's it. But if you want to start getting more real-world, then things to think about: Off design conditions. You can perfectly optimize efficiency at one condition (i.e. for a ...

3

The Cessna 172S has more power (180hp vs 160hp for 172R) and higher MTOW (2550lb vs 2400lb for 172R). This means that folks used to rotating at 55 knots IAS in earlier models would be closer to stall if taking off "clean". Another way of doing it would be to add 5 knots and rotate clean at 60 knots. Vx is also a bit higher in the 172S at 62 knots ...

3

A fan blade at the front or turbine blade at the back of a jet engine is a small aerofoil surface which is fixed to the main shaft and spins with it. By contrast, a stator vane is a similar aerofoil surface fixed to the outer casing and remains static. Why do that? The spinning blades of a given stage cause the airflow to start spinning, and that slows the ...

2

Technically speaking any airplane generates maximum lift just before the wings come off. Whether that is interesting to obtain or not, depends on your need for adrenaline. During a normal flight in a one engine GA airplane, the moment at which most lift is created is during the first few seconds after rotation. In more agile airplanes like military jets, ...

1

Plugging in some values using a True Airspeed calculator seems to confirm Peter Kampf's conclusion that the "steps" are indeed coinciding with transonic flight at various IAS and altitudes. There for, there is no "over lapping" of the curves, though they appear to be on the graph. One might suggest the flattening of the curve once the ...

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