1988 SP Air Race - Improving your chances - 1

1988 State President's Trophy Air Race


A series of three articles written by Vic Kaiser prior to the 1988 Air Race

Part 1

Due to the high level of competition that has developed over the past years, I feel it is time to give the less experienced competitors some guidelines and techniques to improve their performance in this race.

First and foremost is NAVIGATION. The shortest distance between two points is the straight line that joins them (correct for the distances covered in this event). Unless you fly the track represented by that line on your map you will he covering a longer distance and hence reducing your chances of gaining time. Now if you are on your desired track you should also have no problem in locating the turning point early and position yourself such that you can be seen and positively identified. Penalties must be awarded if you are not identified at a turning point.

Another factor to consider under navigation is the TERRAIN you cover. Study your route carefully on the preceding day and calculate the change in elevation of the terrain enroute. Depending on the excess power. climb performance, of your aircraft, decide then when and where to climb. Rather climb early and plan for a "cruise climb" where you decrease your speed by say 10 knots whilst climbing at 200 - 300 fpm rather than flying right up to the high ground and then executing a steep climb at a much lower speed.

Associated with terrain are UP/DOWN DRAUGHTS as well as WIND. When flying in an updraught don't try to maintain level flight but rather maintain your attitude and use the updraught to gain altitude which you can later trade for extra speed. Conversely, when encountering a downdraught fly down with the draught as far as possible changing your attitude gradually to avoid contact with the ground rather than an abrupt attitude change to maintain altitude. If however, you are very low, this obviously may not be possible.

While the above reasoning applies to crossing a ridge at say 90 degrees, when flying parallel to a ridge, you may choose to maintain a constant altitude and use the updraught to increase your speed.

Similarly expect updraughts on the windward side of the high ground and downdraughts on the leeward side and then apply the technique as discussed above. Bear in mind the manoeuvre limits of your aircraft when you encounter turbulence associated with the wind formations surrounding high ground.

Should the terrain be very flat and free from man-made obstructions and power lines AND you have the confidence and ability to do so you may elect to fly in "ground effect". When flying in ground effect, the cushion of air below you generates additional lift. Now if you were to keep your height constant and hence your lift, you will find that your true airspeed will increase slightly whilst maintaining a constant height above the ground. Just remember to trim slightly nose up when applying this technique. This technique, however, is not recommended whilst flying over undulating terrain, as you will be in this year's race.

However, ground effect is only effective up to a height of approximately 1/2 a wingspan. As you can see not only is it extremely difficult to fly at such a height, but additional problems with low level navigation are also encountered. (SAPFA note - this practice is actively discouraged as it increases risk significantly with an extremely low probability of a speed gain)

If you experience a tail wind cruise climb to gain altitude but remain in the tail wind as long as possible so as to maximise its effect.

Bear in mind however, if you climb too high you may he climbing "out of" a tailwind "into" a headwind segment and thereby cancel out any advantage given by the tailwind. Try to ascertain every few 100 feet whether you are gaining or losing in groundspeed before continuing. A good cue to look for lower down is to watch the ground features such as windmills, to determine the actual wind effect. The altitude gained, i.e. potential energy, can then be converted into a higher airspeed, kinetic energy. When approaching the turning point remembering that turn radius increases with an increase in speed. In order to minimise your radius of turn you will now have to increase your load factor, "g". Know your aircraft's structural limits as well as your own "g" capability and execute a minimum radius turn without "blacking-out" or high speed stalling whilst flying the track plotted on your map.

Also correlate the effect of a tail wind on your present leg to the next leg, as it may give you a headwind component on your next leg and thereby force you to alter your altitude. Similarly, when experiencing a headwind, change your altitude so as to minimise the negative component for the shortest time possible. Also ensure you are on track all the time whilst flying into a headwind, as any deviation will mean extra distance to be covered and hence a longer time spent in the headwind.

This article will be continued in next month's issue and we will take a look at other factors, such as drag, weight, C of G, trim as well as various other flying techniques. By analysing each of these effects on your performance we hope to improve your chances of winning this race.