The third generation ultralights, arriving in the early 1980s, have strut-braced wings and airframe
structure. Nearly all use 3-axis control systems, as used on standard airplanes, and these are
the most popular. Third generation designs include the CGS Hawk, Kolb Ultrastar and Quad City
Challenger. There are several types of aircraft which qualify as ultralights, but which do not have
fixed-wing designs. These include:
Weight-shift control trike: while the first generation ultralights were also controlled by weight shift, most of the current weight shift ultralights use a hang glider-style wing, below which is suspended a three-wheeled carriage which carries the engine and aviators. These aircraft are controlled by pushing against a horizontal control bar in roughly the same way as a hang glider pilot flies. Trikes generally have impressive climb rates and are ideal for rough field operation, but are slower than other types of fixed-wing ultralights.
Powered parachutes: cart mounted engines with parafoil wings, which are wheeled aircraft.
Powered paragliding: backpack engines with parafoil wings, which are foot-launched.
Powered hang glider: motorized foot-launched hang glider harness.
Autogyro: rotary wing with cart mounted engine, a gyrocopter is different from a helicopter in that the rotating wing is not powered, the engine provides forward thrust and the airflow through the rotary blades causes them to autorotate or "spin up" to create lift. Most of these use a design based on the Bensen B-8 gyrocopter.
Helicopter: there are a number of single-seat and two-place helicopters which fall under the microlight categories in countries such as New Zealand. However, few helicopter designs fall within the more restrictive ultralight category defined in the United States of America. Two examples that do are the Mosquito Air and XEL designs from Innovator
In most affluent countries, microlights or ultralight aircraft now account for a significant percentage of the global civilian-owned aircraft. For instance in Canada in October 2010, the ultralight aircraft fleet made up to 19% of the total civilian aircraft registered. In other countries that do not register ultralight aircraft, like the United States, it is unknown what proportion of the total fleet they make up. In countries where there is no specific extra regulation, ultralights are considered regular aircraft and subject to certification requirements for both aircraft and pilot.
The United States FAA's definition of an ultralight is significantly different from that in most other countries and can lead to some confusion when discussing the topic. The governing regulation in the United States is FAR 103 Ultralight Vehicles, which specifies a powered "ultralight" as a single seat vehicle of less than 5 US gallons (19 L) fuel capacity, empty weight of less than 254 pounds (115 kg), a top speed of 55 knots (102 km/h or 64 mph), and a maximum stall speed not exceeding 24 knots (45 km/h or 27.6 mph). Restrictions include flying only during daylight hours and over unpopulated areas. Unpowered "ultralights" (hang gliders, paragliders, etc.) are limited to a weight of 155 lb (70 kg) with extra weight allowed for amphibious landing gear and ballistic parachute systems. In 2004 the FAA introduced the "Light-sport aircraft" category, which resembles some other countries' microlight categories.
In the United States no license or training is required by law for ultralights, but training is highly advisable. For light-sport aircraft a sport pilot certificate is required. Ultralight aviation is represented by the United States Ultralight Association.
These were designed as powered aircraft, but still used wire bracing and
usually single-surface wings. Most have "2-axis" control systems, operated
by stick or yoke, which control the elevators (pitch) and the rudder (yaw) --
there are no ailerons, so may be no direct control of banking (roll). A few
2-axis designs use spoilers on the top of the wings, and pedals for rudder control. Examples of 2-Axis ultralights are the "Pterodactyl" and the "Quicksilver MX".
During the late 1970s and early 1980s, mostly stimulated by the hang gliding movement, many
people sought affordable powered flight. As a result, many aviation authorities set up definitions
of lightweight, slow-flying aeroplanes that could be subject to minimum regulations. The resulting
aeroplanes are commonly called "ultralight aircraft" or "microlights", although the weight and
speed limits differ from country to country. (Check out the "Golden Age of Ultralights" video)
The first generation of modern ultralights were actually hang gliders with small engines added to
them, to create powered hang gliders. The wings on these were flexible, braced by wires, and steered by shifting the pilot's weight under the wing. The second generation ultralights began to arrive in the mid-1970s.