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During flight, the four forces acting on the airplane are lift,weight,thrust, and drag. Lift is the upward force created by the effect of airflow as it passes over and under the wing.
The airplane is supported in flight by lift. Weight, which opposes lift is caused by the downward pull of gravity.
thrust is the forward force which propels the airplane through
the air. It varies with the amount of engine power being used.
Opposing thrust is DRAG,which is the backward, or retarding, force WHICH LIMITS THE SPEED OF THE AIRPLANE.
In unaccelerated flight,the four forces are in equilibrium. Unaccelerated flight means that the airplane is maintaining a constant airspeed and is neither accelerating nor decelerating.
(note: turning is considered accelerating!)
In straight and level,unaccelerated flight, lift =weight, and thrust=drag.

2007-03-24 14:13:07 · answer #1 · answered by cherokeeflyer 6 · 1 1

In your analysis it can't.

Drag is dependent on many factors, aerodynamics, surface and lift. As the lift of an aircraft increases so does drag. Fat wings, vertically, carry big loads slowly. Thin wings carry small loads fast.

Swept wings reduce drag but the aerodynamics change near the wing root.

Thrust is a function of power to propel the aircraft. Actually thrust may be a misnomer cuz what gets thing in gear is the ratio of air pressure in front of the engine to the air pressure behind the engine. i.e. EPR, Engine Pressure Ratio. At cruise engine power is set by EPR. On takeoff and initial climb, engine power is measured in Percentage.

If there were only enough thrust to overcome drag there would be a problem cuz there's nothing left for creating air flow over the wing. But if there's no airflow, there's no drag.

I think the two are related but with different elements of concern.

2007-03-24 15:51:48 · answer #2 · answered by Caretaker 7 · 0 4

Well simply to accelerate to say 100km/h your thrust will have to be higher than the drag, as you reach 100km/h and set your thrust to equal the drag, you will not accelerate but remain in constant motion of 100km/h. So technically you are still moving.

2007-03-27 03:59:19 · answer #3 · answered by Anonymous · 0 0

At rest an aircraft's thrust is equal to it's drag. If the aircraft is
accellerating thrust is greater than drag.If aircraft decreases it's velocity drag is greater than it's thrust.In motion at a constant velocity,drag again equals thrust.

2007-03-24 16:02:04 · answer #4 · answered by qwicherbitchen 1 · 1 1

Kinetic energy. It's still moving.

You're assuming that the drag always equals the thrust. Not so! The thrust can exceed the drag, in which case the airplane accelerates and/or climbs. Drag can exceed thrust, in which case the airplane slows and/or falls.

Like that point in approach when they drop the landing gear, full flaps and spoilers... at that point they have more drag than thrust.

2007-03-24 15:20:15 · answer #5 · answered by Wolf Harper 6 · 1 3

If thrust equals drag than the aircraft is not accelerating nor is it decelerating. Example: you are flying along at 100 knts the airspeed is constant (thrust = drag) if you wanted to accelerate to 115 knts thrust would have to be greater than drag (add more power) if you wanted to slow to 95 knts drag would have to be greater than thrust ( reduce power).

2007-03-24 21:07:31 · answer #6 · answered by milehighaviator 2 · 0 2

The only time drag equals thrust is (hopefully) on the ground parked at the ramp... When drag equals thrust, no motion is taking place... that does not necessarily mean it will crash because if you are flying a small plane into a strong headwind you can acutally fly in place... the wind creates enough lift on the wings to keep it going and in rare cases you can fly backward... its not much fun though... kinda like one step foreward two steps back...

2007-03-24 20:18:50 · answer #7 · answered by ALOPILOT 5 · 0 4

You just answered your own question. The drag only becomes equal at level flight speeds, therefore the drag is less than thrust until you get to level flight cruising speed.

2007-03-24 15:14:35 · answer #8 · answered by Delphi 4 · 0 3

Inertia

2007-03-24 18:49:09 · answer #9 · answered by TimTim 3 · 0 1

The plane is falling down

2007-03-25 08:35:22 · answer #10 · answered by sastro 5 2 · 0 1

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