2004 PTAR – Logger analysis

President´s Trophy Air Race

Pietersburg Civil, Polokwane – 10 to 12 June 2004

By Chris Booysen

As in prior years a number of aircraft were fitted with loggers. While it is difficult to come to any significant conclusions from the limited data, there is some interesting information that can be extracted from the logger tracks.

For those that have not yet come across the loggers, some general information. The loggers were designed by Jan Hanekom and are manufactured by him in Pretoria. They have been approved by the FAI for competition use. While there are two other loggers approved by the FAI, the South African one has the widest distribution worldwide. This is not only due to the quality of the equipment but also to the sophistication of the software that is available to analyse the tracks logged. The software is also local.

The logger basically records the longitude and latitude and altitude every second, in other words the three dimensional position of the aircraft every second. Using these plotted positions the software can calculate the heading, climb/decent and ground speed of the aircraft.

The logger information has been used as one of the tools for setting handicaps and as a tool to detect the use of GPS in aircraft. The shortage of logger units has been a problem as this has prevented their extensive use.

This year the logger was used in determining the handicap speed of non standard and home built aircraft. Loggers were also put into aircraft in the race on both days. On day two the loggers were put into the leading aircraft from day 1. We also have tracks from some privately owned loggers.

The total distance actually flown by the Race winners, Harry Antel and Barry de Groot for the two days was 651.957 miles. This compares to the actual distance of the race of 649.50 miles. The logger track shows that they did go off the direct track on occasions one must remember that at times slightly left or right of track might save an unnecessary climb. Their average speed over the distance they actually flew (ie including off track errors)was 134.9 as opposed to their speed achieved of 134.37 and handicap speed of 127.50

Another aircraft that had a logger for both days was LXR. The total distance actually flown by them for the two days was 651.8 miles. An additional distance of 2.3 miles. Their average speed over the distance they actually flew was 197.9 as opposed to their speed achieved of 197.13 and handicap speed of 195.64

FNH was slightly lost on the leg to Warmbaths on day 2. The actual distance flown by them on day 2 was 332.151 miles or 5.751 miles longer than the course. Their average speed for the distance they flew was 118.661 knots as opposed to their handicap speed of 117.0 knots. If they had maintained that speed for the two days and stayed on course they would have gained 4 minutes 39 seconds which would have moved them up four places.

WZU lost time at Giyani on the first day (approx 4 minutes). The actual distance flown by them on day 2 was 329.017 miles or 2.617 miles longer than the course. Their average speed for the distance they flew was 198.57 knots as opposed to their handicap speed of 193.65knots. If they had maintained that speed for the two days and stayed on course they would have gained 4 minutes 59 seconds which would have moved them up 17 places but they still had no chance of winning the race.

There was one track logged on day 1 that was very accurate. A bit too accurate for my liking. I am sure that if loggers were being used to detect GPS then this track would have been subject to investigation. The aircraft was never more than 100 feet off track for the whole race

I have drawn no conclusions from the facts above. I do not believe that there is sufficient data and information to make any generalisations. What is interesting to note that the aircraft that were test flown tended to be in the middle of the field and their actual speeds were close to their handicap. Does this mean that aircraft handicapped with the use of logger information have more accurate handicaps. It is the intention to introduce more and more loggers in the aircraft until every aircraft flies both legs with a logger and logged aircraft information is used for purposes of determining the handicap of the participants.