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"Asok is clearly right my friend. The J-20 did NOT need to use afterburners during its Zhuhai demonstration. Hence why all of us believe it has a powerful engine regardless of origin."
This guy
@pakistanipower don't even know, what is Afterburner or Vertical climb is. The videos he listed clearly showed the F-16 used the AfterBurner (the videos showed it has a
red hot flaming butt) all the way, and there is NO vertical climb demonstrated.
And he clearly doesn't agreed, with the high school level physics, that to do a sustained vertical climb (not a loop or mere high angle climb), one needs to have a
TWR > 1, or F/W > 1.
What a joke!
https://www.grc.nasa.gov/www/K-12/airplane/fwrat.html
View attachment 421720
Note the last line, I highlighted.
F/W > 1.0 (TWR > 1.0 ) Can Accelerate Vertically.
"There are
four forces that act on an aircraft in flight: lift, weight, thrust, and drag. Forces are
vector quantities having both a magnitude and a direction. The
motion of the aircraft through the air depends on the relative magnitude and direction of the various forces. The
weight of an airplane is determined by the size and materials used in the airplane's construction and on the payload and fuel that the airplane carries. The weight is always directed towards the center of the earth. The
thrust is determined by the size and type of
propulsion system used on the airplane and on the throttle setting selected by the pilot. Thrust is normally directed forward along the center-line of the aircraft.
Lift and
drag are aerodynamic forces that depend on the shape and size of the aircraft, air conditions, and the flight velocity. Lift is directed perpendicular to the flight path and drag is directed along the flight path.
Just as the
lift to drag ratio is an efficiency parameter for total aircraft aerodynamics, the thrust to weight ratio is an efficiency factor for total aircraft propulsion. From Newton's
second law of motion for constant mass, force F is equal to mass m times acceleration a:
F = m * a
If we consider a horizontal acceleration and neglect the drag the net external force is the thrust F. From the Newtonian
weight equation:
W = m * g
where W is the weight and g is the gravitational constant equal to 32.2 ft/sec^s in English units and 9.8 m/sec^s in metric units. Solving for the mass:
m = W / g
and substituting in the force equation:
F = W * a / g
F / W = a / g
F/W is the thrust to weight
ratio and it is directly proportional to the acceleration of the aircraft. An aircraft with a high thrust to weight ratio has high acceleration. For most flight conditions, an aircraft with a high thrust to weight ratio will also have a high value of
excess thrust. High excess thrust results in a high rate of
climb. If the thrust to weight ratio is greater than one and the drag is small, the aircraft can accelerate straight up like a rocket. Similarly, rockets must develop thrust greater than the weight of the rocket in order to
lift off .
NOTE:
We must be very careful when using data concerning the thrust to weight ratio. Because airframes and engines are produced by different manufacturers and the same engine can go into different airframes, the thrust to weight ratio of the engine alone is often described in the literature. High thrust to weight is an indication of the thrust efficiency of the engine. But when determining aircraft performance, the important factor is the thrust to weight of the aircraft, not just the engine alone. Another problem occurs because the thrust of an engine decreases with altitude while the weight remains constant. Thrust to weight ratios for engines are often quoted at sea level static conditions, which give the maximum value that the engine will produce."