The EoN Primary, or Elliotts AP/7 Primary EoN as it is known in full, is a more modern but essentially very similar version of the Dagling/SlingsbyT-3 Primary and SG 38 formula of the 1930s for a simple single-seater basic training glider.
The prototype made its first flight in February 1948, and the first production model flew in April that year; the type was used not only by clubs but by the Air Training Corps and Combined Cadet Force under the service name of Eton TX Mk 1 to replace the Daglings previously used for Cadet instruction. It could also be supplied with a static training stand which acted as a simple flight simulator in which the glider was balanced on a pivot and wind forces assisted the trainee pilot to get the feel of the controls.
The constant chord wooden wing is wire-braced and has a high lift section of 12% thickness/chord ratio; it has a plywood leading edge and fabric covering, with fabric-covered wooden ailerons. Plywood leading edge spoilers are featured for use during ground-slides only. The fuselage is a flat wooden open girder-type structure supported by a horizontal beam with the landing skid underneath, with sprung compression legs; the pilot has a single open seat with minimum controls. Unlike the Dagling and Slingsby Primary, the EoN design did not have the option of a nacelle to provide some protection for the pilot. The tail unit is of fabric covered wooden construction and strut and wire braced, effective fin area being provided by filling in part of the open rear fuselage in front of the rudder.
Production of the EoN Primary ended in 1958 after 80 had been built, but a number of these were still at Elliotts’ works at Newbury ready for final assembly in the spring of 1965, not long before Elliotts ceased all glider production.
Span: 34 ft 0 in 10.36 m
Length: 20 ft 6 in / 6.25 m
Height: 8 ft 0 in
Wing area: 180 sqft / 16.72 sq.m
Aspect ratio: 6.0
Empty weight: 250 lb / 113 kg
Max weight: 490 lb / 222 kg
Wing loading: 2.8 lb/sq.ft / 13.7 kg/sq.m
Max speed: 73 mph / 117 kph
Max aero-tow speed: 54 mph / 87 kph
Stalling speed: 27 mph / 43.5 kph
Max L/D: 8
All Aero 