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RCH
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The Feared downwind turn
from RCH
wrote 1 year 15 weeks ago
Disagree------
C G of the earth should be the reference point. Level flight is circular motion because of the shape of the earth. Thrust and drag determine the airspeed.
When turning downwind the drag tries to decrease--but thrust will accelerate the aircraft
relative to the Great Circle around the earth if the time span is long enough. If the time span is to short---there will be a loss of airspeed.
In a rate one turn (3 degrees / sec) it takes one minute to turn 180 degrees. In the example above the aircraft would accelerate 100 mph in one minute relative to earth. If the ball in the turn and bank is centered--the g force is going to be on the seat of your pants. You are already pulling about 1.15 G's ---my old body would not be able pick up the small difference in G force.
In comment 2 (aerodynamically the airplane sees no difference). IMHO the aircraft experiences changes in the drag which causes acceleration if turning downwind and negative
acceleration in an upwind turn relative to the earth.
The Feared downwind turn
from RCH
wrote 1 year 12 weeks ago
to maddogdriver
From-----http://physics.info/acceleration/
Acceleration occurs anytime an object’s speed increases, decreases, or changes direction.
If an airplane is flying straight and level in a no wind situation –it is experiencing acceleration due to change in direction, caused by the curvature of the earth.
If the airplane is flying level and turning in a no wind situation---it is experiencing a second acceleration due to change in direction horizontally.
If the airplane is flying level and there is a wind blowing horizontally---the airplane is experiencing three accelerations—two directional and one increase in speed if turning downwind or a decrease in speed if turning upwind relative to the earth. All these accelerations can happen at a constant airspeed if the time span is long enough and the airplane flown correctly.
These accelerations and some other ones are used in an Inertial Navigation System.
The Feared downwind turn
from RCH
wrote 1 year 12 weeks ago
To AF6IT
Hope this will help answer your question------
An airplane is cruising at 120 knots (2 degrees of the Great Circle per hour), flying straight and level (circular motion). It is equipped with standard flight instruments and an Inertial Navigation System (accelerometers are the sensors for this unit). There is no wind. The airspeed and the INS indicated speed in the gravitational field of the earth are the same. Some time later we notice during a thirty second time period the indicated INS speed has increased to almost 150 knots (2.5 degrees/hr). The airspeed has remained constant. The airplane has flown into a 30 knot tailwind. The airplane has accelerated, proven by the accelerometers in the INS. Thrust and drag determine the airspeed. Thrust and drag act as a governor –seeking equilibrium –if the drag tries to decrease, thrust will accelerate the airplane relative to the Great Circle so the airspeed remains almost constant.
Turning upwind to down wind and acceleration
from RCH
wrote 1 year 3 weeks ago
Disagree---there is the force of the moving air (wind) relative to the earth accelerating the aircraft relative to the earth if the aircraft is able to convert the kinetic energy of the air to motion relative to the earth. The human body cannot differentiate the difference in g force, but an Inertial Navigational System can.
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