07.03.2009 Social Issues

How to fly the aeroplane

By Daily Graphic
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How does a pilot control the aeroplane? What are the main controls and how do they work?

I consider myself the most privileged pilot in Ghana, since I get to introduce so many Ghanaians and those of other nationalities to flying and controlling an airplane every week.

I share this experience of flight to inspire new generations towards greater achievements as well as inform the more mature generation so that they can share with their communities the value of aviation and 'how it works.

When those in Europe and America teach controlling and flying an airplane, they tend to make assumptions about previous experiences. Many young people in such locations have been around aircraft of different sizes from an early age, and often know somebody who owns a small aircraft.

They have probably visited aerospace museums, been in 'full motion simulators' at entertainment centres, and have generally played video games related to flying or three-dimensional movement.

Furthermore, the education systems tend to be a little bit more 'techno-centric' than here in West Africa, therefore, a lot of the sensations and visual inputs are almost taken for granted.

Here in West Africa our exposures are different. Do not get me wrong; by different I do not mean less good; not at all, I mean just different. Consequently, over the years I have had to find different ways of looking at the initial training of young and not quite so young student pilots. Please, bear with my explanations which (although incomplete technically) should help to convey the principles and encourage a greater understanding of, and interest in aviation.

One of the biggest challenges is how to explain the way things work on an airplane; albeit that it really is quite simple in its actions. Flying an airplane when you are in the air is relatively easy. To 'taxi' along the ground is not complicated. Taking off requires a degree of coordination.

Navigation is a challenge and requires good calculation skills and observation. However, landing is the big one! In learning to fly, an average student pilot has a working knowledge and ability to control the principal controls within approximately three hours of in-flight training, and is probably comfortable on a straightforward take-off.

However, landing is another story altogether.... Talk to anybody who has learned to fly, and they will tell you that they spent more time practising landings than any other single 'phase offlight'.

Landing combines more precise control of all the flying techniques and, therefore, pilots still practise landings after many thousands of hours of flight in order to hone their skills even further.

Airplanes, or more precisely in this case, 'fixed wing aircraft' (basically meaning, not helicopters), rely upon the movement of air over the wings to generate what is called 'lift' to keep the plane in the air. This same movement of air over the 'control surfaces' enables the pilot to control the movement of the aircraft.

Propulsion: Most of us have travelled in a motor vehicle of some sort, be it a motorbike; car or tro-tro and we have all seen that the wheels turn around, powered by the engine, to make the vehicle move or to propel it forward. This is achieved by the engine turning the wheels against the ground. Such a means of propulsion cannot work for the aircraft, since it is not in contact with the ground for very much of the time, only for taxiing (the movement of an airplane on the ground is called Taxi, but that has nothing to do with public transport!).

In order to move the airplane forward, an engine will be used to collect the air in front of the plane and to throw it behind the plane. This can be done with a propeller (a bit like a fan) or a compressor type system called a jet engine.

We will consider the propeller since it is most common on training aircraft. If you put a standing fan on wheels it would move in the opposite direction to where the air is being sent. This is called 'Thrust' and the amount of thrust is determined' principally by the speed at which the engine turns. Therefore the pilot can increase the thrust by increasing the throttle setting, by pushing the throttle lever or knob forward with his hand, which increases the engine revolutions per minute (rpm) which turns the propeller faster, which creates more thrust, and thus the plane overcomes the drag or friction that resists its movement, in order to move forward. I guess that this makes the 'air' equivalent to the road, and the propeller equivalent to the tyres of a car.

When you see a pilot inspecting the propeller, it is because it so important to have the 'prop' in good condition if you are to get the most out of your engine. Also airplanes do not have selectable gears like in a car, but sometimes the angle of the propeller can be changed in flight to have a similar effect. Now, do not be confused about thrust and speed they are not as linked as you might think, as we will find out later.

Turning - Roll and Yaw
Our cars turn due to the contact between the road and the vehicle's wheels on the road. Airplanes, though, cannot enjoy this simple system! In fact, turning an airplane requires two coordinated movements: that of 'rocking' the plane left/right (roll), and changing the direction of the nose-to-tail line of the plane: 'yaw' (pronounced as in Yawn).

In order to roll the plane, we have small panels at the rear of the wings and towards the outside of them that can go up and down, called ailerons. When the pilot moves the controls to the left, the left aileron will go up and the right aileron will go down, which makes the right wing lift up and the left wing move down.

At the same time, the pilot will use his feet to push on the left pedal to make the rudder (a moveable panel mounted vertically at the very back of the plane) move to the left, which pushes the tail to the right, and the nose to the left.

Together this creates a turn. If it is carried out well, the airplane can be at quite an angle from the normal level appearance, and yet onboard the aircraft there is no sliding of people to the left as you would expect if a car were to be at such an angle!

To understand this better, take a bucket of water, tie a rope to the handle and swing it around, even as the bucket 'turns' the water level remains parallel to the top and bottom of the bucket. This is the same principle used by pilots in a coordinated turn using ailerons and rudder together in just the right combination.

It should be remembered that when the plane is at the desired 'angle of bank' (which determines how quickly the plane turns), the controls are returned to neutral position until it is time to stop turning. Then the opposite. aileron and opposite rudder are applied together to 'roll' and 'yaw' simultaneously back to the 'straight and level' attitude (as it is called when we fly in a straight line), wings level without going further up (climbing) or down (descending). When not changing 'attitude' the controls return to the neutral position.

Ups and downs or Climbing and Descending: One of the most amazing sights we get to see is when an airplane leaves the ground and climbs into the sky. It may appear as if there is an invisible mountain with a straight road underneath the plane and it just rides up into the sky, but that is not the case. The truth is that, when the airplane has enough speed of air over its wings, all the pilot has to do is gently (and I do mean gently) pull the controls back towards rum. This makes the horizontal panel at the rear of the plane, called an elevator, move up which pushes the tail down and the nose up.

Conversely, in order to go down, the pilot gently pushes the control forward which lowers the elevator, pushing the tail up and the nose down, until the desired angle is achieved. This up or down angle is called pitch or attitude. A nose-up attitude or nose down attitude should now make sense!

Speed: Speed is controlled by two factors, much as it is in a car. If you are driving your car up a hill you will need more power to maintain a certain speed. Likewise, when driving down a hill you will use less power for the same speed. It is very similar in an airplane. On takeoff, when the pilot wants to climb or gain an increase in distance between it and the ground (measured in feet above the sea and called 'altitude'), the pilot will use full power and point the nose skywards (control back) and fly at, let us say, 80km/hr. When flying straight and level the pilot will probably only use three-quarters of the power and fly at, let us say, 120km/hr. However, when coming in to land, the pilot will have perhaps only half power and nose down (control forward) and fly at, let us say, 100km/hr!

If a pilot increased thrust while descending, the speed at which altitude is lost would become very alarming, so we reduce power as we descend. Similarly, imagine the driver of a car increasing the accelerator speed while driving down a steep hill - it is simply not done!

This leads to the pilots' adage 'Throttle controls rate of climb/descent and stick controls speed'. The 'stick', or more correctly 'joystick', is the name given to the control that is held in one hand and can move backwards, forwards, left and right to control 'pitch' .and 'roll'. In some planes this is replaced with a sort of 'half steering wheel' called a 'column' which can be turned to the left or right for roll and pushed and pulled to control pitch. Pilots argue sometimes over which is better, but one thing is for sure in my book, and that is that the stick is more natural and quicker to respond to movement and learn with than the column. Regardless, when you have learned to use either the stick or the column, it is easy to use the other one.

Horizon: It seems that many young people are not taught, or perhaps do not understand, what the horizon is, so forgive me if I explain it here. The horizon is the point in the distance where the sky appears to meet the land or the sky appears to meet the sea. When we are flying visually (by looking out of the window), the pilot looks at the horizon to judge whether he is climbing, descending or turning. If we cannot see out (at night or when in clouds,) we use an instrument called an 'artificial horizon' or 'attitude indicator', when flying visually and especially when learning to fly, it is very important to look out, and to use the horizon to 'feed your senses' with the correct signals of movement in the new environment of flight to know that your control inputs are giving the desired effects!

So in summary:
• Thrust is controlled by the hand- operated throttle, which controls the engine power.

• Roll is controlled by the stick, held in the hand, moving left and right which controls the ailerons.

• Yaw is controlled by the rudder pedals with your feet, which controls the rudder.

• Pitch is controlled by the stick, held in the hand, moving forwards and backwards which controls the elevator.

• Rate of climb and speed are related to the combination of thrust and pitch.

• The pilot looks at the horizon when flying visually to know how the aircraft is reacting to the control inputs given.

When you next see an airplane in the sky manoeuvring, consider the above and see if you can see any of the control surfaces (rudder, elevator and ailerons) moving!

• Capt Yaw is Chief Flying Instructor and Chief Engineer with WAASPS Ltd, Aviation for Development, at Kpong Airfield, near Kpong in the Eastern Region

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