The only glider manufactured by Swiss aircraft manufacturer. First flying in 1972 the Pilatus B4 is an all-metal design to Standard Class specifications. It has full aerobatic capability including inverted maneuvers.
The B4 is a cantilever shoulder-wing monoplane with a T tail; the wings are of light alloy with a U-shaped light alloy main spar and hard PVC foam ribs between the metal ribs; the large skin panels are attached to the main spar by a single row of countersunk rivets, and the ailerons are of similar construction. There are light alloy spoilers in the wing upper surfaces at the 60% chord line. The semi-monocoque fuselage is also of light alloy, with a flush-riveted skin, and the rear fuselage consists of two half-shells riveted together. The light alloy T-tail has PVC ribs and a fixed-incidence tailplane, and the elevator has a bias spring for trimming. The landing gear consists of a non-retractable unsprung Tost monowheel with drum brakes, although a retractable one can be fitted if the customer desires, and there is a fixed tailwheel; small doors enclose the monowheel when retracted. The pilot sits in a semi-reclining position under a sideways-hinging canopy that is jettisonable in flight, and a battery radio and oxygen system are optional.
Certification for full aerobatic manoeuvres was granted in January 1975. Of all-metal construction, the type was designed by Ingo Herbot as a private venture and first flew in prototype form, as the B-4, in 1966; the design was taken over and developed by Pilatus as the B4-PC11, which first flew in 1972. Swiss certification was granted on 12 June that year, and the first delivery was made shortly afterwards. Seventy‑eight B‑4s were sold in 1977, and 320 were in operation.
More than 330 examples of the Standard Class Swiss single-seater had been delivered to customers in no less than 30 countries by March 1978, and the production rate was as high as 7-8 aircraft per month.
On 19 June 1978 Pilatus announced the sale of all manufacturing and sales rights in the B4 to the Japanese firm of Nippi - Nihon Kikoki Kabushiki Kaisha (or Japan Aircraft Manufacturing Co Ltd) so as to be able to concentrate on production and development of the PC-6 Turbo-Porter and PC-7 Turbo-Trainer.
The first Nippi-built B4-PC11 AF was rolled out on 1 June 1979 and initial production was to be at three per month after Japanese certification. The first Nippi-built B4-PC11 AF made its maiden flight on 25 November 1979. Pilatus was to continue the product support of Swiss-built examples.
Number of aircraft built to 6/30/81 400.
Wing Span: 15m / 49.2ft
Wing Area: 14.04sq.m / 151.1sq.ft
Length: 21 ft 7in
Height: 5 ft 2 in.
Empty Weight: 230kg / 506lb
Payload: 120kg / 264lb
Gross Weight: 350kg / 770lb
Wing Load: 24.93kg/sq.m / 5.13lb/sq.ft
Min Sink @ 39 kts / 45 mph: 0.64 m/s / 2.1 fps / 1.24 kt
L/D Max: 35 @ 85 kph / 46 kt / 53 mph
Max speed: 129 kts / 149 mph (in smooth air)
Stall speed: 33 kts.
Rough air airspeed: 86 kts
Max aero-tow speed: 112 mph
Airfoil: NACA 64(3)-618
Aspect ratio: 16.1