V Speeds etc

RE: V Speeds etc

Keep studying guys there maybe a future for you in the avition industry.Kabir ypur analysis is looking pretty sound to me
well done

RE: V Speeds etc

nah did a project on them last year.

RE: V Speeds etc

Yeah got it in books but can’t b arsed typing up – looks like u found a nice website their!

RE: V Speeds etc

Wow Kab. Thanks for this.

Regards

Ben

RE: V Speeds etc

V1- Maximum speed in the takeoff which the pilot must take the first action to stop the airplane within the accelerate-stop distance
Va- Design Maneuvering Airspeed
Vef- Speed at which the critical engine is assumed to fail during takeoff. Pilot must decide to stop or go.
Vf- Design flap speed
Vfe- Maximum flaps extended speed
Vle -Maximum speed with landing gear extended
Vlo- Landing gear operating speed
Vlof- Liftoff speed; the speed at which the wheels leave the ground
Vmc(a)- Minimal Controllable Airspeed (airborne)
Vmc(g)- Minimum controllable airspeed (ground)
Vne -Never exceed speed
Vno- Maximum structural cruising speed
Vr -Rotation speed with control input
Vsi- Stall speed in a specific configuration (usually gear & flaps up)
Vso- Stall speed in the landing configuration
Vx- All engines best angle-of-climb speed
Vxse -Engine-out best angle-of-climb speed
Vy- All engine best rate-of-climb speed
Vyse -Engine-out best rate-of-climb speed
Vzrc- Zero rate-of-climb speed for set weight & conditions
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B737-400 TAKE OFF SPEEDS:

TOW-737-400 23.5K
1000kg-V1 VR V2
70-158 162 168
65-152 154 162
60-144 147 155
55-137 139 149
50-129 131 143
45-121 123 136
40-112 115 130
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Bernoullis Principal:

P + ½ r V² = constant

The equation doesn’t take compressibility effects into account but at airflow velocities below 300 knots there are no such effects – thus no change in density. The equation then indicates that, in a moving airstream, if velocity increases static pressure must decrease.

Another aspect to the equation is that the constant is the stagnation pressure – the pressure energy needed to halt the airflow – thus it can be written P + ½ r V² = stagnation pressure. Note the stagnation pressure is the highest pressure in the system. This aspect of Bernoulli’s is used in the air speed indicator – as demonstrated below – but it is also the basis of the powered parachute wing. Those wings consist of an upper and lower fabric surface enclosing individual front opening cells. In a moving air stream the cells are at stagnation pressure – the highest – and thus form the semi-rigid wing shape.

There is another equation of aerodynamic interest to us – the continuity equation. This states that, in a moving airstream, the product of density, velocity and cross sectional area must always be a constant.

r × A × V = constant

If there is no change in density then we can state that

A × V = constant.

Thus if air flows into a smaller cross section area, or around an object, velocity must increase to maintain the constant and Bernoulli states that if velocity increases static pressure must decrease; so the velocity of a constricted airstream increases and its static pressure decreases.

Both these equations are related to the conservation laws – Bernoulli’s to the conservation of energy and the continuity equation to the conservation of mass.

NOTE: The V theories are also based on the flight envelopes.
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ON THE BASIS OF THIS LAW BY BERNOULLI AVIATIONS V THORIES OF TAKE OFFS AND LANDINGS ARE BASED ON.
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RE: V Speeds etc

Yes, as Preston has mentioned, there are simply too many variables affecting the values of V1 and V2 to make it simple to work out at hand, especially without data (whether, aircraft weight, length of TORA etc…)

Regards

Ben

RE: V Speeds etc

too many differant conditions to type up – i got a whole chapter in a book on em – for a start what type of a/c – obviously a 757 and Fokker 50 will b diff, what winds?, rwy surface? atmospheric pressure, weight, thrust retardation on take off? and for the fuel you need enough for 2 approaches and a diversion – not such an easy question to answer in general!