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Flight Instructor Patter Ex12&13

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  Exercise 12 Take Off Aim To learn the techniques of taking off, climbing and positioning the aircraft on the downwind leg of the circuit. Definition The take off is a linear acceleration considered to start when the aircraft is accelerated under its own take off power on the ground until flying speed is reached, whereupon the aircraft is rotated and leaves the ground for flight. Newton’s Laws Let’s look at the forces acting on the aircraft at the beginning of the take-off roll.Full power is applied but there is no drag while there is no movement. The external force, thrust, will accelerate the aircraft. This acceleration will be proportional to the amount of thrust ( power given) and inversely proportional to the mass of the aircraft. As speed increases drag will increase and as long as the thrust is more than the drag the speed will increase. Inertia must also be kept in mind. Critical Stage of Flight Although take-off seems like a relatively easy manoeuvre to perform it is the most dangerous and critical  part of every flight because of the many factors effecting the take-off. This is also the first time that the engine is developing full power. Should there be any problem with the engine , or contaminated fuel you will most likely have to deal with the problem shortly after take-off which is not the best scenario for an engine failure i.e. you will be low and slow. Factors Effecting the Take-off Density Altitude: When you are at a high elevation airport and the outside temperature is high then the air is going to be very thin. This decrease in air density effects the aircraft negatively in three ways: 1.The engine does not develop full power (unless it has a turbo ). Less air means less power.2.The propeller produces less thrust in less thinner air.3.The wings need more speed to develop the same amount of lift because of the decreased density.Can you see that this will have a nasty effect on the take-off run and climb performance. It is not difficult to realise that the air is thin and that the take off might be a problem, but it is also not difficult to determine exactly if a safe take off will be possible. It is determined as follow:The International Standard Atmosphere ( I.S.A.) is based on averages around the world and is a model or measuring stick that is used to determine an aircraft’s performance. ( If the pilots operational handbook says the service ceiling is 15 000ft, it is 15 000ft in this I.S.A.Explain how to determine Density Altitude.For example; If the density altitude is 7500ft at sea level the aircraft will perform as if it was flying at 7500ft in the I.S.A. which is much higher than sea level. With this figure you can go to the pilot operating handbook and extract the take off distance and climbing performance for the prevailing conditions and weight, keeping in mind that a new aircraft was used to determine the performance data. Performance is  based on density altitude. So when in doubt, take the pilot operating handbook and work it out. Don’t take achance.Another factor is Humidity. Water vapour is lighter than air so an increase in humidity means an increase indensity altitude. This factor is not easily expressed in numbers, but definitely one which should be kept in mind. Be careful of the three H’s: Hot, High and Humid.  Technique The correct technique is essential for a safe take off. The elevator must be kept neutral until the correct speed is reached. You will be able to rise the nose wheel off the runway at quite a low speed, but this will add drag and the thrust will be slightly inclined. Flaps Optimum flap during take off will shorten the take off roll be cause the stall speed is decreased, but once airborne it will have a negative effect on the climb because of the increased drag.Flaps should be used if the runway is short but used carefully if there are obstacles ahead. With some aircraft the use of flap is recommended and others not. ( Consult your pilot operating handbook. ) Weight As discussed under Newton’s laws; the acceleration of the aircraft on take off will be inversely proportionalto the weight of the aircraft . Thus the heavier the aircraft the more runway will be needed to take off and the slower the climb out will be. One of the very important reasons not to over load an aircraft. Surface and Gradient A hard, firm surface like asphalt is the best. Grass (being rough) and dirt (loos sand) strips will cause more friction to the wheels increasing the take off run.What would be best, uphill or downhill ? Downhill because acceleration will be quicker. Wind Taking off into wind is better because before you even start the take off run you will all ready have some airspeed i.e. if the wind speed is 15kts you will have 15kts of airspeed when you are lined up. Therefor the take off speed will be reached sooner, using less runway. The climbing angle will also be improved. Taking off with a tailwind will have the opposite, negative effect to both take off distance and climbing angle. Crosswind Take Off  As you accelerate the into wing will develop more lift because of dihedral. ( Sideways airflow will cause anincreased angle of attack on the into wind wing this causes the into wind wing to produce more lift.) This iscountered by lowering the aileron on the into wind wing. The runway centre line is maintained with rudder. Rotate speed is a bit higher to assure that when you become airborne it is positively away from the ground. Remember to neutralise the ailerons just be fore rotating. Once airborne the nose will weathercock into the wind. Track the centre line by keeping the ball in the centre with rudder. Effect of Power – Swing on Take Off  At take off the slipstream and torque effects are very prominent due to the full power at low airspeed. On the runway the aircraft will yaw to the left because of the slipstream effect and the fact that the left wheel has more friction than the right wheel because it is pressing harder against the runway due to the torque effect. As you get airborne the torque effect will tend to roll the aircraft to the left. These effects must be countered by using right rudder. The Short Field Take Off  It is a take off in the shortest possible distance. Optimum flap should be used and as little as possible runway should be wasted when lining up. Apply full power and check engine parameters before break release. Rotate speed is slightly lower because of the flaps being used. If obstacles pose a problem, climb out at the best angle of climb speed with gentle turns into the wind away from the obstacles. Once clear of  the obstacles accelerate to the best rate of climb speed before retracting the flaps. Refer to the pilot operating handbook for the correct procedure of a specific aircraft type. The Soft Field Take Off  This is performed when the runway is soft, rough, covered with tall grass, slush or snow. It is done with optimum flap and it is a rolling take off. (do not stop when lined up.) Apply full power gradually and simultaneously full aft elevator, to keep the weight of the smaller nose wheel. The nose will come up early in the take off run, keep it in the rotation attitude with elevator control. Becoming airborne release back  pressure slightly in order to accelerate to the applicable climbing speed. EmergenciesAborted Take off: Should anything go wrong while still on the ground; you must abort the hake off by closing the throttle and applying brakes as necessary.Here are some reasons for aborting a take off:Lose of power or if the engine is not developing full  power.Abnormal indications on engine instruments.Unusual vibrating or rough running.Airspeed not increasing.Door or window opens.Obstruction on the runway.Any other emergency or problem.If there is any problem straight after take off or during the climb out your most important task is to fly the aircraft. Continue the take off, maintain climb speed and direction. Climb to a safe altitude or if safe to do so fly a circuit and land before trying to sort out the problem. Shortly after take off while you are low and slow is no time to try and close a door for instance. Engine Failure After Take Off  The most important is to lower the nose (no matter how low you are) to the gliding attitude instantly.During the climb out the speed is relatively low and the nose attitude is high. thus the airspeed will rapidly decay if the nose is not lowered quickly. Then you select a suitable open area within 30   either side of the extended runway centre line to do an emergency landing. Through out maintain best glide speed until rounding out for landing. The reason for staying within 30   either side of the extended runway centre line is the following:Let’s say you want to turn through 90  . Because you are low and descending you don’t have a lot of time. So to make the field you need to turn steep which will increase the rate of descend, thus you don’t make thefield.  Exercise 13 Circuit Joining Procedure and The CircuitAim To learn those techniques required to execute accurate circuits and landings under all conditions. Definition The formal definition of an aerodrome traffic circuit is: The specified path to be flown by aircft operating inthe vicinity of an aerodrome. Circuit Joining Procedure The standard joining procedure at an unmanned airport is as follow:Join overhead at 200ft A.G.L. to determine the wind direction. this will allow you to choose the correct runway for landing. also to consider when choosing a runway is the length, gradient and obstacles around the different runways. When overhead we also look at the signal square (traffic pattern indicator) and other traffic. While maintaining a good look out, descend to a 1000ft A.G.L (circuit height) on the dead side of the pattern to join the circuit on a crosswind position, reporting your intentions on the appropriate frequency. This is the standard procedure; NOTAMS, traffic pattern indicators and local rules must be adhered to. The Circuit A standard circuit is a left hand circuit because the pilot sits in the left hand seat thus it provides better visibility.                 2                9 1         1          Runway UpwindCrosswindDownWindBase legFinalApproach A circuit consists of the take off, cross wind leg, down wind, base leg and final approach.Take off and climb to downwind: The aircraft takes off the from the runway in use after which the undercarriage and flaps are retracted and power is decreased to climb power. the aircraft then climbs on the extended centre line to 500ft above the ground. A climbing turn is then executed through 90   to positionon the cross wind leg. On the cross wind leg the aircraft is levelled off at circuit height (1000ft above the ground) and accelerated to a slow cruising speed. When the runway is at 45   to the aircraft a turn is executed through 90   to position on the downwind leg. Downwind to final approach: The downwind entails straight and level flight parallel to the runway. During this leg the aircraft is configured for landing. Once the runway as at an angle of 45   the aircraft is turned through 90   to position on the base leg. On the base leg the aircraft is placed in a descend to intercept the extended runway centre line at a height of about 700ft above ground.Remember the whole idea of the circuit is to position the aircraft in a suitable position for a good approach and landing.( A good landing starts on downwind.)

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Sep 10, 2019

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Sep 10, 2019
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