The popular characterization for this kind of flying is "stunt flying." Pilots who engage in this activity are sometimes thought to be crazy daredevils. This romantic and somewhat sensational view is common in the media because it is exciting. It sells advertising and gets attention. The reality is very different.
Aerobatics competitors belong to the International Aerobatics Club (www.iac.org), an organization of pilots who work to improve their skills and perfect the accurate performance of aerobatics figures and routines to exacting standards.
Judges grade the contestants, much like the figure-skating contests popular in the Winter Olympic Games. Aerobatics pilots are sober, careful individuals who take pride in the attention they give to the safe flying and maintenance of their airplanes.
Aerobatics is a physically and mentally challenging sport that takes years to learn and a lifetime to master. World class pilots start with some natural talent, then dedicate thousands of hours in the air and more on the ground to train to be the very best.
As with the best baseball and football players, many desire the goal and few attain it. Unlike baseball and football players, the financial rewards are few. The primary reward is more like that of Olympic class athletes. It is the pleasure of having succeeded in creating a physical performance that is highly demanding, difficult, and sometimes beautiful to watch.
Biplanes are popular in all but the highest category of aerobatic competition. Most of the biplanes you will find at a regional contest such as the Kathy Jaffe Challenge were designed by one man, Curtis Pitts, and are generically referred to as "Pitts Specials." The wing construction uses wooden spars and ribs with steel wire reinforcements all covered with fabric. The fuselage is welded steel tubing. The fuselage from the engine to the cockpit has sheet-metal covering. The remainder of the fuselage and tail has fabric covering.
Photo by Stephen Seidel
While the Pitts dominated aerobatics in the 1960's, world class aerobatics is now dominated by high-performance monoplanes. There are many different monoplane models. Some of their names are, Sukhoi, Yak, Zlin, Extra, Cap, Edge, and Giles. Most have a welded steel tubing fuselage. Some use fabric covering; some use sheet steel. The latest models use lightweight carbon composite material.
All of the competitors at IAC sponsored contests perform their aerobatics figures in a safe zone called the "Aerobatic Box." The box keeps competitors in front of the judges.
The box lies over a one square-kilometer area on the ground delimited by white markers visible from the air. The markers show the corners, the center, and the center of each side. One kilometer is about 3,300ft.
The altitude for the bottom of the box varies for different levels of competition. The most advanced pilots may descend as low as 300ft above the ground. The beginning pilots must remain over 1,500ft above the ground.
There is a maximum altitude for all pilots of 3,500ft. This keeps the pilots low enough to be seen by the judges.
Most airplanes, and all airplanes in aerobatic competitions, are controllable in three dimensions. The names of the three dimensions are "pitch," "roll," and "yaw."
Pitch is motion of the airplane's nose up and down. An airplane will generally climb as the nose (pitch) goes up and descend as the nose (pitch) goes down. When an airplane rolls the wingtips move up and down. Yaw is motion of the airplane's nose side-to side.
An airplane turns by coordinated use of pitch, roll, and yaw. An airplane that has rolled into a turn is sometimes described as being "in a bank," or "banked," as if following a banked, high speed curve in a road.
Point your web browser to the EAA Young Eagles Web site at www.youngeagles.org for an excellent interactive demonstration of pitch, roll, and yaw.
An aerobatic sequence is a series of clearly defined aerobatic figures. Aerobatic figures are individual maneuvers such as loops and rolls that begin and end with horizontal, level flight (upright or inverted). The system of diagramming aerobatic figures and sequences was developed by Jose L. Aresti in the early 1960's. It shows what a pilot is expected to fly in a manner similar to the way music shows what a musician is expected to play.
The paragraphs that follow describe some of the notes, or aerobatic figures that appear in an aerobatic sequence. They show the Aresti symbol, give the name of the figure, and provide a short description of some of the things the judges look for in the figure.
Powered airplane competitions of the International Aerobatic Club have five categories, or levels of competition of increasing level of difficulty. The five categories are Primary, Sportsman, Intermediate, Advanced, and Unlimited.
The following paragraphs explain each category and show an Aresti diagram of the 2005 known compulsory aerobatic sequence for that category.
The Primary category is the most basic, entry level category of aerobatic competition. Pilots must demonstrate a spin, loop, roll, and competition turns.
The Sportsman category offers a greater challenge to the beginning competitor. It includes a greater number and variety of figures, including the hammerhead (figure 6).
Sportsman competitors may design a "free" sequence. A free sequence is a sequence of the competitor's design that satisfies constraints on the type of figures flown, the number of figures, and the total amount of difficulty of the sequence.
The Intermediate category adds the snap roll and some inverted figures. Intermediate competitors must provide a free program. If there is time at the contest they may also be required to fly an "unknown" compulsory sequence.
The Contest Director provides the unknown sequence to the competitors at least 18 hours before the competitors must fly it. Competitors may have practiced many of the figures in the unknown, but have no opportunity to practice the sequence before performing it for the judges at the contest.
You may see competitors doing a strange dance next to their airplanes as they rehearse the sequence on the ground before their flight.
The 2005 Intermediate Known included a snap roll on a forty-five degree down line (Figure 7), a roll integrated in a loop (Figure 10), an inverted exit from Figure 5 and entry to Figure 6, and an inverted quarter-turn (Figure 13).
The Advanced category includes more challenging figures with multiple rolls and snaps on each figure and more inverted figures. The Advanced category adds the rolling turn.
Advanced pilots fly a known compulsory, free, and unknown compulsory sequence.
The 2005 Advanced Known included a snap on a vertical down line (Figure 2), a rolling three-quarter turn (Figure 4), and opposite point rolls (Figure 9).
The Unlimited category is the most difficult of all. Only the most capable pilots flying the most capable airplanes can manage the figures required in the Unlimited category.
Pilots flying Unlimited are flying at the level of air-show performers and world competitors.
The 2005 Unlimited Known included snap rolls on a vertical line up (Figure 1), combinations of snaps and rolls (Figures 4, 5, and 9), and negative snap rolls (Figures 6 and 9). The sequence also included a tail slide (Figure 8).
For more information about the International Aerobatic Club (IAC) see www.iac.org
For more information about the local IAC Chapter 52 sponsoring the Kathy Jaffe Challenge, including membership, aerobatics rides, and getting started in aerobatics see www.iac52.com
This introduction was written by Douglas Lovell and is Copyright 2005, 2006 IAC and IAC Chapter 52.
Copyright (c) 2001 - 2012 Douglas Lovell