**There are intriguing topics about aerobatics that I believe will interest Smoke-On-Go readers. For example, designing sequences that create high scoring illusions, or discussing the mysteries of mental and emotional preparation, or the distinctive ‘styles’ of different world champions. Before we can visit these topics in future articles, we first need to understand some basics. My challenge is that an explanation of rules may be bland, but I’ll do my best to try not make it so.**

**Modern competition aerobatics is hard core science.**

Modern competition aerobatics is a hard-core science, period! There is however still a little room for artistry. If you get the technical science right, you are likely to do quite well with, perhaps, a third or second placing. However, to win you need to get the illusive arts mastered too.

Aerobatics must be highly technical in order to be fair and objective. Like gymnastics, it comprises graceful movement that is enjoyable to watch. Yet, underpinning the superficially simple spectacle is a plethora of detailed rules.

**A judged aerobatic flight is called a sequence**

A judged aerobatic flight is called a sequence. A sequence comprises of a number of aerobatic base figures (or manoeuvers), normally between ten and fifteen, that are flown in a strict order, and according to meticulous judging criteria.

**The Aresti aerobatic system.**

The Aresti aerobatic shorthand system adopted internationally in 1964, is still used today. Aresti organizes all aerobatic figures into nine main groups or families. Some of these are, for example – loops, rolling circles, lines and angles, stall-turns, tail-slides, rolls and spins, and so on.

Each family is then further divided into sub-families. For example, Loops will comprise of whole loops, half loops and three quarter loops, etc. For just the simple ‘whole loop’ there are 24 different variants in that they may be round, square, diamond shaped, six-sided, inside or outside and upright or inverted, amongst others.

Initially, Aresti had approximately 3000 figures. Later this grew to over 15000. The number still changes as new figures are added, and others are consolidated. The system is still evolving.

Each figure can be ‘dressed up’ with one or two rolls per line. For example a basic stall turn can have a ¼ roll on the up-line, followed next by a three quarter roll. Then, after the turn around, a three quarter flick roll on the down line followed by two points of an eight point roll. Similarly, loops can include different roll combinations. The permutations of base figures and different roll additions mean that there are literally millions of options that can be used to design a sequence.

**Each manoeuvre (figure) has a difficulty co-efficient.**

All figures have a K or difficulty factor. The K-factor multiplied by the score awarded for a figure, gives the total points for that figure. For example an ordinary stall turn has a K-factor of 17K. By adding the rolls as described above (and shown in the following schematic) a figure giving a K-factor of 47K is arrived at.

The sum of the points for all the figures gives the total sequence score (expressed as a percentage). Half a percent difference between first and second place is not uncommon. Negative scoring is applied, as pilots start with a full ten points. Then, as each figure is flown, judges subtract points for errors.

**There are five classes in aerobatics**

There are five classes in aerobatics – Graduate, Sportsman, Intermediate, Advanced and Unlimited. Regardless of the aircraft used, or the class flown, the judging criteria are the same. A loop is always a loop.

The differences between the classes include, firstly, the figures that can be flown. Flick rolls are flown for the first time in the Intermediate Class, tail-slides in the Advanced Class, and negative flick rolls in the Unlimited Class. The second difference is based on the maximum points or the K factor permitted for a sequence. The Sportsman Class allows a maximum of 220K, and the Unlimited Class a maximum of 420K. A third difference is the minimum height allowed. For the Sportsman Class, the hard deck is at 1500ft above ground level and for the Unlimited Class it is 300ft.

**Some basic but important judging criteria.**

The judging criteria for each figure are beyond the scope of this article, but here are a few basics.

**Geometry** – A loop must be perfectly round. For a square, diamond or six-sided loop, the length of each line must be the same. All lines must be perfectly vertical (up or down), or perfectly horizontal (inverted, erect or knife edge), or perfectly on the 45degree line, up or down, inverted, or erect. Radii must be consistent.

**Rolls** – These must start and stop crisply, with no ‘bobbles’. For example, when flying a four point hesitation roll, the stops must occur exactly at every ninety degrees of rotation. The rate of roll and the pause time for each hesitation must be consistent.

**Line balance** – Rolls must be positioned in the centre of any line.

**Positioning –**The entire sequence must be placed inside a 1000m box, and preferably right in front of the judges. Championships are very often won or lost on the positioning score. Consider that it takes just four seconds for an Extra at full speed to transition the entire box. Then add a strong crosswind factor and one can then understand why positioning is a challenge.

Now that the groundwork has, I hope, been established, we can discuss the more exciting aspects of this sport in future articles.