New answers tagged

3

Transport aircraft are certificated to a maximum operating temperature for departure that is related to International Standard Atmosphere (ISA), typically 35 deg C above ISA (there may be airplanes certified to ISA +40), ISA being 15C at sea level and dropping from there at the standard adiabatic lapse rate . ISA temperature at Phoenix airport at 1135 ft ...


2

We want to reduce (or simplify) equation 2, to get get dV/dt by itself, so we multiply both sides by g/W. On the right hand side, this reduces to dV/dt. On the left hand side it reduces to what is given in equation 3, but let me show you how: 1. First term is T x g/W 2. Second term is -D x g/W 3. Third term is -u x g/W (W - L). By the distributive ...


5

With my old VariEze (not a training aircraft; in the same power class as the Cessna 152 but lighter and with much higher wing loading) I had a cruise propeller and a climb propeller that I could exchange on the ground with about 30 mins of work. I measured ground roll at max gross weight and calm wind to be around 1500' with the cruise prop and 1100' with ...


3

"Naked Pilot" by David Beaty suggests that this technique was introduced by engineers following Foote's accident. Behind the scenes, BOAC and de Havilland were worried too. The manufacturers had been doing further tests and a new take-off technique was introduced. The nose-wheel had to be lifted off the ground at 80 knots, but afterwards it had to be ...


13

The 1952 takeoff accident you read about was piloted by Captain Harry Foote. The technique got its name after the accident, which Captain Foote was blamed for (Comet! The World's First Jet Airliner, page 125). Pushing the nose down is not standard though, rather a corrective measure to over-rotation past 6°. The article quoted below covers the proper ...


12

At the time of the Comet disasters, Vr did not exist. The standard takeoff technique was what was used on all previous airplanes - line up, release the brakes, apply full power (derated thrust did not yet exist), accelerate, apply some back pressure to take the weight off the nose wheel, start feeling the airplane off the ground. The problem was that the ...


1

Tires. Tires are under very high stress normally due to the compromise between extreme performance requirements and low weight. Tires aren't cheap. By doing a higher-speed-than-necessary takeoff, you're increasing tire wear and inviting tire problems that you just don't need to invite. It would be a very false economy to save a little in what exactly, ...


4

The term I'm coming across the most is "static take-off" (even used by Airbus). Its advantage is that it's using the least distance since you don't "waste" the distance it takes the engines to spool-up (in a jet anyway) to take-off power. Not to be confused with "non-rolling take-off", which just means the aircraft was holding on the runway before the ...


3

It is theoretically possible to do a flaps up take off if you have a long enough runway, but why would you want to? An airplane is designed to be most efficient in the air, so the sooner you get there, the better. The lift available to an aircraft is proportional to the area of the wings (and flaps increase that area), however, the drag those wings produce ...


3

Several other good answers, but one reason I haven't seen yet is pilot proficiency. You don't want pilots only practicing short-field takeoff and landing technique on actual short fields, which might be rare depending on 5he routes any given pilot happens to fly. If they use that technique on every takeoff and landing, though, then you know they'll always be ...


9

For an aircraft designed for cruising efficiency it is important to have as little trim drag as possible. See ATR 72 link: The wing may appear unusually small, but it is made to produce the needed lift at cruising speed at its most efficient Angle of Attack, where lift to drag ratio is highest. If the wing produced too much lift for level flight at its ...


5

In addition to the previous answers, you could argue that yes: provided you had a long enough runway you could theoretically perform a takeoff run that accelerates you to a speed which is sufficient for taking off and remain airborne with no flaps (and for this exercise let's assume an A320 has a flaps-up speed of 210 knots, give or take), but you'd be ...


9

One function of common inner span flaps that's not often discussed is stall management. Not only does some flap lower the stall speed, but it ensures the wing root stalls while the tips are still flying; this prevents an incipient stall from turning into a low altitude stall-spin if a wind gust or unplanned maneuver pushes the aircraft from "controlled ...


7

Aside from the decreased takeoff speeds, there are a couple reasons why typical Part 25 aircraft do not allow flapless takeoff: There is usually a sweet spot at lower flap settings that generate the best climb gradient at V2, and it's usually not with flap retracted. It is typical to see several takeoff flap settings that cater to best climb and best field. ...


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