Aerobatics is the practice of flying manoeuvres involving aircraft attitudes that are not used in normal flight. Aerobatics are performed in airplanes and gliders for training, recreation, entertainment, and sport. Additionally, some helicopters, such as the MBB Bo 105, are capable of limited aerobatic manoeuvres. The term is sometimes referred to as acrobatics, especially when translated.
Most aerobatic manoeuvres involve rotation of the aircraft about its longitudinal (roll) axis or lateral (pitch) axis. Other manoeuvres, such as aspin, displace the aircraft about its vertical (yaw) axis. Manoeuvres are often combined to form a complete aerobatic sequence for entertainment or competition. Aerobatic flying requires a broader set of piloting skills and exposes the aircraft to greater structural stress than for normal flight. In some countries, the pilot must wear a parachute when performing aerobatics.
Manoeuvres were flown for artistic reasons or to draw gasps from onlookers. In due course some of these manoeuvres were found to allow aircraft to gain tactical advantage during aerial combat or dogfights between fighter aircraft.
Aerobatic aircraft fall into two categories—specialist aerobatic, and aerobatic capable. Specialist designs such as the Pitts Special, theExtra 200 and 300, and the Sukhoi Su-26M and Sukhoi Su-29 aim for ultimate aerobatic performance. This comes at the expense of general purpose use such as touring, or ease of non aerobatic handling such as landing. At a more basic level, aerobatic capable aircraft, such as the Cessna 152 Aerobat model, can be dual purpose—equipped to carrying passengers and luggage, as well as being capable of basic aerobatic figures.
Flight formation aerobatics are flown by teams of up to sixteen aircraft, although most teams fly between four and ten aircraft. Some are state funded to reflect pride in the armed forces whilst others are commercially sponsored. Coloured smoke trails may be emitted to emphasise the patterns flown and/or the colours of a national flag. Usually each team will use aircraft similar to one another finished in a special and dramatic colour scheme, thus emphasising their entertainment function.
Teams often fly V-formations (otherwise known as echelon formation)— they will not fly directly behind another aircraft because of danger from wake vortices or engine exhaust. Aircraft will always fly slightly below the aircraft in front, if they have to follow in line (the “trail formation”).
Aerobatic manoeuvres flown in a jet-powered aircraft are limited in scope as they cannot take advantage of the gyroscopic forces that a propeller driven aircraft can exploit. Jet-powered aircraft also tend to fly much faster which increases the size of the figures and the length of time which the pilot has to withstand increased g-forces. Jet aerobatic teams often fly in formations which further restricts the manoeuvres that can be safely flown.
To enhance the effect of aerobatic manoeuvres smoke is sometimes generated; the smoke allows viewers to see the path travelled by the aircraft. Due to safety concerns, the smoke is not a result of combustion but is produced by the vaporization of fog oil into a fine aerosol, achieved either by injecting the oil into the hot engine exhaust or by the use of a dedicated device that can be fitted in any position on the aircraft. The first military aerobatic team to use smoke at will during displays was Fleet Air Arm 702 Squadron “The Black Cats” at the Farnborough Air show in September 1957.
Aerobatics are taught to military fighter pilots as a means of developing flying skills and for tactical use in combat.
All aerobatic manoeuvres demand training and practice to avoid accidents. Such accidents are rare but can result in fatalities. Low-level aerobatics are extremely demanding and airshow pilots must demonstrate their ability before being allowed to gradually reduce the height at which they may fly their show.
Competitions start at Primary or Graduate level and proceed in complexity through Sportsman, Intermediate and Advanced, with Unlimited being the top competition level. Experienced aerobatic pilots have been measured to pull +/-5g for short periods while unlimited pilots can perform more extreme manoeuvres and experience higher g levels -possibly up to +8/-6g. The limits for positive g are higher than for negative g and this is due to the ability to limit blood pooling for positive g maneuvers, but it is generally accepted that +9 g for more than a few seconds will lead to loss of consciousness (also known as GLOC).
Aerobatics are most likely to be seen at a public airshows.
Reference: Wikipedia Aerobatics