To address the evolution of the ultralight vehicle and its community of sport users, the FAA issued new rules on September 1, 2004. These rules created a new category of LSA and a new classification of FAA pilot certification to fly LSA, called Sport Pilot. Additional guidelines established by the FAA can be found in 14 CFR part 61. [Figure 1-12] This section focuses on the WSC aircraft.
Aircraft certificated as LSA exceed the limitations defined for ultralight vehicles and require that the pilot possess, at a minimum, a Sport Pilot certificate. The sport pilot rule defines the limitations and privileges for both the sport pilot and the LSA. In addition, the regulations governing the sport pilot rule define the training requirements of prospective sport pilots and the airworthiness requirements for their machines. For instance, an ultralight vehicle must not exceed 254 pounds or carry more than one person. Aircraft that carry more than one person and weigh over 254 pounds but less than 1,320 pounds may be certified as LSA provided they meet specific certification requirements. Therefore, many WSC ultralight vehicles became LSA (provided they were properly inspected and issued an airworthiness certificate by the FAA).
Weight-Shift Control Aircraft
WSC aircraft are single- and two-place trikes that do not meet the criteria of an ultralight vehicle but do meet the criteria of LSA. The definition for WSC can be found in 14 CFR part 1. Flight control of the aircraft depends on the wing’s ability to flexibly deform rather than on the use of control surfaces.
The common acronyms for this LSA are WSC (weight-shift control); WSCL (WSC land), which can be wheels or ski-equipped; and WSCS (WSC Sea) for water operations. A LSA WSC used for sport and private pilot flying must be registered with an FAA N-number, have an airworthiness certificate, a pilot’s operating handbook (POH), and/or limitations with a weight and loading document aboard. The aircraft must be maintained properly by the aircraft owner or other qualified personnel and have the aircraft logbooks available for inspection. Dual flight controls are required in two-seat aircraft used for training.
The carriage is comprised of the engine and flight deck attached by a structure to wheels, floats, or skis; it may also be referred to as the fuselage. The wing is the sail, structure that supports the sail, battens (ribs) that form the airfoil, and associated hardware. [Figure 1-13]
There are several unique features of the WSC aircraft:
- The wing structure is in the pilot’s hands and is used to control the aircraft. There are no mechanical devices between the pilot and the wing. The pilot can directly feel the atmosphere while flying through it because the pilot is holding the wing. This is a direct connection between the wing and the pilot like no other aircraft.
- The pilot can feel the wing as the wingtips or nose moves up and down, but the carriage and passenger are more stable. Turbulence is not felt as much as in a fixed-wing aircraft.
- Different wings can be put on a single carriage. This allows the pilot to have a large wing that can take off in short distances, which would be good for low and slow flying. A large wing with a lightweight carriage can also be used for soaring and is capable of flying at speeds below 30 miles per hour (mph). At the other extreme, a smaller high-performance wing can be used for flying long distances at high speeds. With a small wing and a larger motor, WSC aircraft can fly at speeds up to 100 mph.
- The wing can be taken off the carriage and folded up into a tube that can be easily transported and stored. This allows owners to store the WSC aircraft in a trailer or garage, transport the WSC aircraft to a local site, and set it up anywhere. [Figure 1-14]
- Since the WSC aircraft is designed without the weight and drag of a tail, the performance is significantly increased. The aircraft can take off and land in short fields, has good climb rates, can handle a large payload, has a good glide ratio, and is fuel-efficient. The WSC LSA typically can carry 600 pounds of people, fuel, and baggage.
Besides having large and small wings for different speeds, the WSC aircraft wings can have wires for bracing, struts, or a combination of both. Throughout this handbook, both are used in diagrams and pictures. WSC aircraft are typically on wheels, but there are models that can land and take off on water and snow. [Figure 1-15]
Weight-Shift Control LSA Requirements
A WSC LSA must meet the following requirements:
- A maximum takeoff weight of not more than—
- 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or
- 1,430 pounds (650 kilograms) for an aircraft intended for operation on water
- A maximum airspeed in level flight with maximum continuous power (VH) of not more than 120 knots calibrated (computed) airspeed (CAS) under standard atmospheric conditions at sea level.
- A maximum stalling speed or minimum steady flight speed without the use of lift-enhancing devices (VS1) of not more than 45 knots CAS at the aircraft’s maximum certificated takeoff weight and most critical center of gravity.
- A maximum seating capacity of no more than two persons, including the pilot.
- A single reciprocating engine.
- A fixed or ground-adjustable propeller.
- Fixed landing gear, except for an aircraft intended for operation on water.
- Fixed or retractable landing gear, or a hull, for an aircraft intended for operation on water.