Glider Pilot 2

A comprehensive simulation of a modern glider, written specially for the BBC Micro in collaboration with a gliding instructor.

Features

1. Cable Launch
2. Practise Approach and Landing
3. Thermals with three difficulty grades
4. Navigation Map
5. Beacons for cross-country flights
6. 'Solid' colour graphics and sound
7. Perspective view of runway and horizon at all times
8. Extensively machine coded for quick response

Instruments include:

1. Airspeed Indicator
2. Variometer
3. Altimeter
4. Binnacle Compass
5. Artificial Horizon

For Disc Users Only:
Notebook: An easy-to-use memopad utility with fully automatic file-handling.

Introduction

Welcome to the world of soaring flight...

A glider of course has no engine, yet it is able to stay aloft sometimes for many hours at a time. In order to accomplish this, it must rely on air currents to gain height. The air is in constant although invisible motion all the time. We are always aware of the horizontal motion (wind!) but the vertical moition is not so obvious to the earthbound, and is only seen as clouds and occasional rising dust, smoke, paper, etc.

The glider pilot however is very much aware of the vertical air currents, since both his sport and sometimes his life depend on being able to make the best use of them. There are three types of rising air (lift) which can be used by the glider pilot to gain height. These are:

1. Thermal
2. Ridge
3. Wave

Ridge lift is only found in the immediately vicinity of a ridge or hill and is caused by moving air rising to pass over the ridge. It rarely gives lift of more than two or three times the ridge height.

Wave lift is caused by air having passed over high land e.g. a mountain range, repeatedly 'bouncing' on its descent, created several areas of lift which often extend high into the atmosphere. In England, heights of over 30,000 ft. have been reached.

This simulation is concerned only with Thermal lift, caused when a body of air becomes less dense than its surroundings, usually by contact with a warm section of ground or an increase in humidity, and starts to rise. As it rises it forms a 'doughnut' shape, with air rising up the central column and falling down the outside. As the doughnut rises, the air expands and cools until a cloud is formed. If the humidity is low, clouds may not be seen, but this does not mean that thermals are not present.

In the simulation you will be launched to a height of 800-1500 ft depending on the wind strength and your skill during the launch, and then you will attempt to locate thermals which drift down wind (always Westerly) towards you. Points will be awarded for height reached, height gain, time aloft, beacons rounded and landing back at base. No landing points are awarded unless your initial launch height exceeds 500 ft.

The Aircraft

The glider simulated in this program is a modern medium performance machine with most of the instruments normally found in such an aeroplane, and some specific to this simulation (indicators for spoilers, rudder, pitch and inverted flight). It is fitted with three stage spoilers which reduce the lift of the wings and increase drag to assist with the landing approach.

It will fly at a glide angle approaching 30:1, i.e. it can travel 30 feet horizontally fot 1 foot loss of height. In order to accomplish this, it has long narrow wings and low drag. Speed must be increased in a turn to avoid stalling (loss of lift and break up of air flow over the wings). If a stall occurs when banked, there is a danger of stalling the inside wing which is moving more slowly than the outside wing.

If such a tip stall occurs, the stalled wing will continue to drop and the aircraft will fall into a tight spiral dive until speed has built up sufficiently to regain control. To recover quickly from a tip stall, or a straight stall, you must immediately drop the nose of the glider to pick up speed, even when near the ground. A stall at low altitude can be fatal! *So watch your speed when turning.*

The aircraft is also capable of flying inverted (although rather reluctantly!) and may be either rolled or looped to get upside down. If rolling to invert, build up plenty of speed first to avoid a tip stall. If looping to invert you must speed up to at least 80 knots then pull back hard on the stick. Incidentally, the term 'knot' represents one nautical mile per hour, a nautical miles being approximately 1.15 times a standard mile. It can be thought of as around 100 ft./min, particularly useful when considering rates of climb and sink.

If you stall when pointing steeply upwards, there is a danger of a tailslide. In this case it is possible to rip off the control surfaces which are not designed for such treatment! If this happens above 500 feeet you will have time to bale out, otherwise you've had it! If your speed goes above 120 knots you will get an overspeed warning (not normally fitted to gliders), and if you exceed 150 knots the glider will disintegrate! Again if over 500 feet you can bale out successfully.

Instrumentation

There are two rows of instruments and indicators on the dashboard. The top row from left to right reads:

Spoiler indicator
Airspeed indicator
Variometer (lift/sink in knots)
Altimeter
Rudder position indicator

The second row reads:

Binnacle compass
Pitch indicator
Joystick position
Aircraft inverted indicator
Artificial horizon

Launching

Before launch you will be asked to input your weight to determine loading conditions and stall speed, then you are offered the option of a practice approach or a launch. If you decide to launch you will be asked to choose the degree of difficulty (see under Thermalling for details). You will then be launched by a ground tow on the end of a wire. If you exceed safe operating conditions by climbing too steeply or banking too far the wire will release automatically. It also releases automatically when the tow vehicles reaches the end of its run. The climb steepness limits during launch are:

Up to 300 ft. 25 degrees of pitch
Over 300 ft. 40 degrees of pitch

Keep roll to a minimum. Steering effect is ignored during launch since the pull from the tow tends to keep the glider heading in the correct direction. Level off just before release (runway end) to avoid stalling.

Flying

Your controls are Potentiometer Joystick or Keys for Ailerons and Elevator, Keys for Rudder and Spoiler. The Elevator controls the Pitch (nose up or down) of the glider and the Ailerons the Roll.

The position of the joystick is shown in the rectangular panel on the dash board. If you are using joystick rather than keys, the joystick symbol will appear just above this panel. You choose between joystick and keys during the launch sequence. To assist in rapid control changes when using keys, the joystick immediately returns to the central position when the opposite roll or *coarse* pitch key is pressed. It is much easier and more realistic to fly using a potentiometer joystick.

The rudder can be used for ground steering after landing, but is primarily to correct the aerodynamics of the glider during a banked turn. On its own it increases drag and causes the glider to yaw sideways without turning, but during a banked turn it reduces sideways slip and gives a more efficient turn, thereby reducing drag. The amount of rudder should be increased for steeper turns to minimise drag.

When flying steadily, you will find that with the joystick centred the aircraft will maintain its angle of bank but gradually return towards zero pitch. In order to make control easier, the simulation is arranged to maintain the existing pitch if it lies between -4 and +4. Since most flying will be done in this region, this eases the workload.

Landing

Line up with the runway in good time, using your instruments to assist you. (See later for Navigation.) Make gentle corrections to your attitude until you are lined up with wings level and with an airspeed of 45 to 50 knots. You should aim to be approximately 300 feet high 500 metres from the end of the runway.

If you are too high, circle or sideslip (bank with opposite rudder) to lose height. Use the spoilers to lose height if you have room. Then descend using spoilers and pitch to control your descent rate until you are almost down, when you should raise the nose to 'float' the glider onto the ground. The landing practice option will set you up at the correct approach position, and you will only need to control your height and descent rate for a perfect landing! Remember that a downwind landing is bad practice and should be avoided whenever possible, and landing crosswind can rip off your skid!

Don't despair if you find things a bit tricky at first. The glider is quite sensitive to stick movements, and there is always a slight delay between making a control alteration and the glider's response.

For your first few flights use the landing practice option and try small control movements to see how the glider responds. Once you have gained confidence, concentrate on getting a good launch. Don't worry at first about getting back to the runway after launching - you can land safely if you keep an eye on your height and rate of sink - aim to have less than -4 sink on touchdown. If flying on keys, use coarse pitch control for major changes in pitch, and fine control to settle the aircraft into the required glide path.

Pressing ESCAPE during flight will return to the launch sequence.

Thermalling

There are three difficulty grades available. Grade 1 has large thermals and shows the distance from the centre of the nearest active thermal. Grade 2 has the same thermals, but no indication is given. Grade 3 has smaller thermals and no indication. You get higher points for higher grades!

When you encounter a thermal you will pass through an area of rapidly sinking air before reaching the area of lift. You should fly quickly through the sink then try to circle within the lifting area. Use your Vario and ASI to judge your condition. The sound of the wind on your glider increases with speed, and this gives a further aid when things get hectic! You will drift downwind with the thermal until it weakens so much that you must leave it or it disappears altogether. A new thermal will then be generated. There will generally be an active thermal within 5000 ft. There is never thermal activity below 500ft.

You should be aware of your drift downwind at all times, particularly on windy days. It is all too easy to find yourself too far downwind to be able to get home, and you will forfeit becaon and landing points if you land out! If you decide to go cross country and claim one or more beacons, you are best choosing a fairly calm day with a high ceiling. The launch will not be so good, but you have a much better chance of a penetrating upwind.

Navigation

Key M will display a map of your area, divided into 2000 metre squares, showing your position, the airfield and beacons. A further press of key M returns to the outside view. Points are awarded for every beacon rounded, with bonuses for more than one beacon in the same flight. Each beacon can only be claimed once per flight. A tone sounds and the beacon is deleted from the map (but not the view) when it is successfully rounded.

When in map code, the instruments are all still operating, and you should use the artificial horizon to check the attitude if the glider. You will be able to fly on instruments alone, but you will find it easier to gauge your attitude when settling into a turn if you switch back to visible mode. Stay in map mode if you want to fly on instruments alone (to simulate flying in cloud).

Very occasionally you may notice a faint false horizon or corruption of the sky from beacons when flying at low level. If this should happen, a jump in and out of map mode will correct the picture. Don't, however, use the map when flying inverted or banking very steeply (more than 45 degrees) - the view will not be restored correctly.

While this simulation will give a sound understanding of the effects of the controls and instruments in a modern glider, the only way really to appreciate the feeling of freedom of soaring flight is to try it yourself! Most gliding clubs have to seated trainers, and welcome newcomers.

In order to get the most out of this simulation you are recommended to read a good book on gliding. An excellent book is 'Gliding' by Derek Piggott, which is extremely readable and contains a wealth of useful information for the beginner and experienced pilot alike. It is available from most Public Libraries.

Game Controls

A/S - Roll Left/Right
? (fine) > (coarse) - Up
* (fine) + (coarse) - Down

or Potentiometer Joystick for Roll/Pitch

Z/X - Rudder Left/Right
O/C - Spoiler Open/Close
M - Map On/Off
@/RETURN - Pause/Resume

For Disc Users Only

The 'Note Book' memopad utility will give you easy and rapid access to information stored on disc files, using the Acorn DFS or compatible systems.

It will access up to 29 files per disc side (more if the filing system in use allows more than 31 files per side) of max. length 18K, each containing information on subjects of your choice.

When you run the utility (after BOOTing the disc and selecting it), you will get a menu of options. Choose option 2. You will see that an Introduction file is on the Disc. Choose this file then scan it using the up and down cursor keys for more details about the program.

The utility is very user-friendly and gives full instructions for every operation, so you should have no difficulty in using it.

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Tape: CHAIN"" (RETURN)
Disc: SHIFT-BREAK