Aerobatics

I

Introduction

Aerobatics, coordinated display of manoeuvres performed by an aircraft. It is used to display the performance and handling abilities of aircraft or pilot, as a flying training technique, for recreation, and as a competitive sport. In technical terms an aerobatic manoeuvre is one in which an aircraft is flown at a pitch angle of 45º or more, or at a bank angle of 60º or more. Aerobatics (from “aerial” and “acrobatics”) is referred to in some countries as akro or acrobatic flying, and can be performed by powered aircraft, gliders, and model aircraft (which are usually radio-controlled). Piloted aircraft, with or without power, must be “type-rated” as aerobatic, ensuring their naturally lightweight design is able to withstand the G forces inherent in such manoeuvres. A typical entry-level aircraft would be the Cessna Aerobat or the Citabria, which are widely used for training and hire, or gliders such as the AS K21. Vintage aircraft such as the Stampe SV4C and Tiger Moth are also popular although increasingly expensive to maintain and uncompetitive in performance. By far the most popular since its inception in 1945, and established as an icon of aerobatics, is the Pitts Special. This biplane had a radical redesign of its wings in the mid-1960s, which made it almost unbeatable for more than a decade. At higher levels it is the Russian Sukhoi SU-31, the French Cap-231, and the German Extra 300 monoplanes, producing over 300 b.h.p. (brake horsepower), and manufactured from advanced composite material, which are extremely popular. These new materials, although challenging the limits of human endurance by allowing aircraft to withstand up to 25 G, also enable the manufacture of stronger gliders, thus increasing their range of manoeuvres.

II

History

The first publicly recorded aerobatic manoeuvre was the Loop, demonstrated by Frenchman Adolphe Pégoud in a Blériot monoplane in about 1913. Similar manoeuvres were recognized and developed as techniques for survival and attack during air combat in World War I. Between World Wars I and II, pilots with surplus aircraft toured Europe and the United States performing display aerobatics in “barnstorming” acts. In the 1930s the discipline became a competitive sport, and in 1934 France hosted the first World Aerobatic Championships in Vincennes, near Paris, attracting over 150,000 spectators. The sport featured in the 1936 Olympics with a purpose-built aircraft, the Bucker Jungmeistr, but World War II halted international contests until a revival in the 1950s, beginning with the British Lockheed Trophy. The first modern World Championships were organized in 1960 by the FAI (Fédération Aéronautique Internationale) and held in Bratislava, Czechoslovakia. The championships are held biennially. In 2003 the 22nd World Championships, held in Lakeland, Florida, United States, were won by the Russian team.

III

Aerobatic Competitions

In competition it is the pilot’s skill that is adjudicated and not the aircraft, although easier handling in a capable machine allows the pilot to concentrate on presentation. There is no gender differentiation in competition, and pilots who take part are rated in terms of ability, starting as Beginner or Sportsman, through Standard, Intermediate, Advanced, and Unlimited, with pilots at each level being restricted to certain manoeuvres and minimum height limitations until competent at the next level. Despite these being competition terms, similar rules ensure the competency of display pilots. The worldwide governing body of competition is the FAI, and the rules and conduct of contests are determined by one of its commission bodies, CIVA (Commission Internationale de Voltige Aérienne), made up of representatives from national aero clubs or delegated associations.

In the 1960s, the Spanish aristocrat and noted aerobatic pilot Colonel J. Luis Aresti revolutionized aerobatics by developing his eponymous system of symbolic notation and catalogue of manoeuvres. Aerobatic figures, of which there are some 15,000, are constructed from the basic elements of manoeuvres taken from a family of nine types: (1) Lines and Angles; (2) Turns and Rolling Turns; Combinations of (3) Lines, (4) Spins, (5) Stall-turns, (6) Tail-slides, and (7) Loops and Eights; and Combinations of (8) Lines, Angles, and Loops, and (9) Rolls. Adopted internationally since 1978, Aresti notation provides both a standard form of communicating across language barriers, and catalogues each element, with a difficulty coefficient or K-factor. When assembled into figures, the sum of each manoeuvre becomes the “K” for that figure which typically is between 8 and 40. When put together into a sequence, whether pre-assigned or chosen by the pilot, the maximum K-factor must be the same for each sequence in that programme. Competition flights take place along two axes of an imaginary box of air, the A-axis running from side-to-side, and the B-axis from back-to-front. The box is a 1000-m cube, its base varying with the level of pilot competency, from as low an altitude as 100 m. Within this box, a pilot performs a sequence of between 8 and 15 figures before a panel of judges who subtract from a maximum 10 points in penalties for deviations from required figures. Scores are multiplied against the “K” for each figure and totals expressed as a percentage of the maximum possible score. Typical scores at international level would be 70 per cent, while high scores might average 85 per cent. National and club level competitions are held under the auspices of national aero clubs or delegated organizations. The United States is most active, with about 900 competitors, having as their governing body the International Aerobatic Club. The United Kingdom has about 300 active contestants, and about 15 annual contests. Its governing body is the British Aerobatic Association. In South Africa the sport is governed by the Aero Club of South Africa. In Australia, the sport is organized by the Australian Aerobatic Club, and in New Zealand by NZ Aerobatic Club. Embryonic in South East Asia, aerobatics is gaining popularity in many parts of the world.

IV

Aerobatic Display

Display flying originates from a requirement to demonstrate an aircraft’s capabilities to potential users. Although not covered by competition rules, the programme will invariably be governed by strict rules to ensure spectator safety, usually regulated by national aviation authorities. A display routine usually demonstrates the safe limits at which an aircraft can be flown, with each display carefully rehearsed and performed by either single or multiple-formation aircraft. These might range from rebuilt vintages such as the Sopwith Camel, to fast-jet, military formation teams vying for national prestige. Probably the most famous of these are the British Red Arrows in their distinctive red and white Hawk jets. Australia has a team known as the RAAF Roulettes, who, operating PC9s, regularly tour South East Asia and the Pacific Rim. Also touring internationally are the American team (the Blue Angels) and the Russian team (the Black Knights).