Slingsby T.42 Eagle
The Eagle high performance tandem two-seater was originally desinged to meet possible ATC requirements and was developed from the Slingsby T36 two-seater project, itself a development of the Sky; the Eagle also owed something to the Skylark series.
Of conventional wood and fabric construction, the Eagle has a high wing of NACA laminar flow section with a main spar and a light secondary spar to carry the plywood-covered ailerons; the wing is plywood covered to the rear spar, the trailing edge being fabric-covered. The wooden fuselage is of braced girder-type construction, with a glassfibre- and ply-covered nose and fabric-covered rear fuselage. The fin and tailplane are ply-covered and the rudder and elevators fabric-covered. Landing gear consists of a fixed monowheel, a nose skid under the forward fuselage and a tailskid. There is a one-piece Perspex canopy and the two pilots have provision for backtype parachutes; the rearmost pilot sits under the wing.
The T42 Eagle 1 prototype first flew on 12 June 1954 and had a cantilever three-piece wing with a slightly swept forward centre section of 20ft span, air brakes in the centre section and no flaps. The second prototype, the T42A Eagle 2, first flew in May 1956 and had a centre section span of 13ft 10in, with a cut-out in the leading edge to accommodate the rear cockpit; the air brakes were repositioned to the outer wings.
The Eagle 2 won the two-seater class in the 1956 World Championships at St Van, France, flown by Commander H. C. N. Goodhart and Captain Frank Foster; its success was the more gratifying because it was not designed as a contest sailplane but rather as a type for advanced training and cross-country soaring, to enable pilots to bridge the gap between the 'C' and 'Silver C' certificates.
The third prototype, the T42B Eagle 3, had the cockpit moved forward to avoid the Mk 2's leading edge cut-out; this version went into production and a total of 17 was built, the price being £1,650.
In 1966-67 an Eagle 3, BGA 821, was converted into the T55 Eagle 4, also known as the Regal, this variant having the centre section span increased to 21ft 3in and the total span to 65ft 7.5in, or 7ft 5.5in more than that of the Eagle 3.
Span: 58 ft 2 in
Length: 27 ft 11 in
Height: 6 ft 0 in
Wing area: 240 sq ft
Aspect ratio: 14.8
Empty weight: 896 lb
Max weight: 1,240 lb
Max speed: 147 mph
Min sinking speed: 2 ft/sec at 49 mph
Best glide ratio: 31:1 at 49.5 mph