Strap on your parachute, fasten your harness, and check the controls - John Nash takes you up in his fully aerobatic simulator that also features aerial combat

If you want to become a flying ace, just type

CLEAR 1000,32256

and Load the decimal machine codes, using data statements to Poke them to the correct addresses. Save this as a machine-code tape file. The routine's functions are to paint in the ground, to vibrate the screen display when you are hit, and to print an instant explosion when you hit the enemy aircraft.

Next, Load the Basic. The program uses 30K when running.

Once you have the Basic entered, Save it on tape, and Run the program, which will set the limits of the Basic system, as well as putting the processor into dual clock mode. You will need to type

POKE&HFFD6,0

before using the cassette interface, to revert to normal mode.

Unless you are an experienced aerobatic pilot, I suggest that you start without the additional complication of enemy aircraft. To remove these, alter lines 435, 505 and 2095 of the Basic by editing a Rem into the very beginning of each line. This deactivates them.

On the left-hand joystick up and down control your engine speed, in the range 600-2,500 rpm. Engine speeds below 1,700 slow you down, while above that, they speed you up. Left and right control the rudder. The button gives you an updated instrument reading.

On the right-hand joystick left and right control your ailerons, giving rolls, and of course, consequent turn. Do not forget that the horizon appears to go the opposite way to the direction of bank. Up and down control your elevators, and give climb and descent, with loss or gain in airspeed as appropriate. The button gives a map except when there are enemy aircraft about, in which case it fires the guns. I shall give you more details about the map later.

Now for the functions of individual keys. M will give a map at any time, showing the aircraft as a small square, and the runway as a box. The two lines south of the runway are the landing entry zone. Also included is a fuel gauge, one of your most vital instruments, as when you run out of fuel, the engine speed drops to 600 and the aircraft flies like a brick.

F is a useful key which puts you back to straight and level at 3,000 feet at a moderate speed. This is a useful panic button if you get really disoriented, but unfortunately is not present on the real thing.

G lowers the undercarriage at speeds below 120 knots. It also raises the undercarriage after take-off.

F lowers the flaps during landing, at speeds below 140 knots. This lowers your stalling speed to 60 knots, but does not affect the stall warning buzzer.

O performs an overshoot on landing, taking you out of the landing routine, and putting you back in free flight. R and C are used as a pair, to initiate and cancel an offset roll respectively.

S is used to start the engine before take-off.

Four instruments are shown at the base of the screen:

These are updated by pressing the left joystick button.

If your ASI drops below 7 on the guage - 70 knots - you will spin. You must then immediately put the stick fully forward, and you will recover in a dive. If you are below 2,000 feet you will not recover in time.

You hear a stall warning horn at less than 80 knots. You must watch the upper limit, VNE - velocity never exceed - as, if you exceed this, the wings fall off! This also has a warning whistle at 7 knots below VNE. VNE is usually 240 knots.

RPM is self-explanatory, controlled by the left stick, and has a range of 6-25 multiplied by 100. Higher speeds use more fuel, but climb better, and increase your airspeed.

ALT shows your height in units of 10 feet for take-off and landing, and units of 100 feet for normal flight.

HDG is the bearing on which you are flying, in units of 10 degrees.

The map will show your movements, so flying on a heading of 00, you will go upwards on the map. Note that you can fly right off the map and will then see nothing.

G and F appear at the base. When short black lines are present this indicates that your flaps or gear are down.

You are now ready for take-off. Run the program, and select T on the prompt. You will get a runway display. Put on full power, and press S. The display will start to move.

Press the left button from time to time; it is better not to hold it in as this slows things down. When ASI reaches 60, pull back on the right stick. You will now take off. When the horizon reaches the base of the screen, put the stick back to centre, to maintain the rate of climb. Retract your gear with G. When you reach 500 feet, all the controls and display start to work fully.

Aerobatics are best done at over 2,000 feet, because of the risk of spinning.

I cannot teach you to fly, but here are some guidelines:

1. To roll, put your nose a little above the horizon, speed 140-180, and roll with aileron, the right stick. Support the nose with upgoing rudder - left stick - when the wings are vertical. The program simulates the way the nose drops in the roll quite realistically.
2. To loop, get as much airspeed as you can and then pull hard to lift the nose. Eventually, the ground will reappeat, first inverted, then erect, provided you do not stall. Outside loops are also possible: you push forward on the joystick.
3. Flat turns can be achieved with rudder alone, and combinations of manoeuvres can be achieved, but one special one is the offset roll. This is rolling while climbing or diving. Because of the display method, you must lock the offset by pressing R after setting the rate of climb or descent, and before rolling.
   
   When the roll is complete, cancel the offset with C. During the offset roll, you will see a small circle on the instrument panel.

If you do not want the bother of taking off, you can start at 3,000 feet by replying 3 to the initial T, L or 3 prompt.

You can practise landing by replying L to the initial prompt, which will put you on final approach. The more conventional procedure is to place yourself in the area demarcated by the two horizontal lines on the map, at just below 1,000 feet, and on a heading of 330 - 30 degrees, roughly north. If you then press L, you will enter the landing routine. Put your wheels and flaps down - F and G - which will only work if your speed is below 120 and 140 knots, respectively. Control your heading with the rudder to keep the runway central. Descend quickly until you are close to the runway, then round out.

You can only land if your speed is below 90 knots, and the horizon is approximately in the middle of the screen. If you mess it up, you will get various messages, but you can press O at any time before landing, and go round again.

When you have mastered the aircraft, try taking on some enemy planes. Reactivate the three lines - 435, 505, 2095 - and RUN.

As soon as you have left the take-off display, an enemy aircraft will appear after a random time, heralded by a beep. He is flying at 160 knots, and will get larger if you catch him up. He dodges, again randomly, and fires off salvoes of four rockets at you, which stay on the screen for a time proportional to the distance between you and him. At the moment these rockets leave the screen, if they are within your gunsight, you will be hit, and receive a damage of "bale out" report. Baling out is automatic, accompanied by a spectacular display.

You can interrupt the program with Break at any time, and restart with GOTO12000. If you have done any editing, however, you must use Run, as editing clears all the variable arrays, and Run resets them.

The alterations shown at the end of the main program will make the Dragon Flight Simulator controllable from the keyboard. The simulator is a little harder to fly, although still quite usable. It was necessary to make the elevator, aileron, and rudder controls self-centring, as, with no stick to indicate the current settings, one soon becomes very confused.

The instructions need some modification, which I have built into the display screens at the beginning of the program. The main differenes are that the aircraft joystick - previously the right-hand joystick - is now controlled by the arrow keys, operating as you would expect - the joystick forward function is now performed by the up arrow. The other control alterations are explained in the listing.

You have to keep pressing S to keep turning to the right. Similarly with the arrow-keys you have to keep pressing the up-arrow to keep pitching up, when doing a loop. If you want to alter the pitch rate, this can be achieved by altering 820 and 825. Try altering HA by

+/-2*V

per key press if you find the pitch too sluggish. The joystick version gives three different pitch rates according to stick deflection. You will also have to be quick to reduce your rpm when entering the landing routine, or you will overshoot.

I would be happy to oblige readers by supplying taped copies of the joystick or keyboard version of the program, for the sum of £4.85, including postage and packing. Write to J. R. G. Nash, 30 Hutchcome Road, Botley, Oxford OX2 9HL.

This game was originally published in Your Computer Vol. 3 No. 6 (Page 86).