Civil Aviation Department of India KS-I Kartik / KS-II Kartik
Several Civil Aviation Department aircraft were named after lunar related periods; Kartik (Sanskrit: कार्तिकः) is the eighth month of the Indian national calendar. The glider named after it was one of at least five designed by S. Ramamrithram at the Civil Aviation Department.
Produced at the Technical Centre of India's Civil Aviation Department, the Kartik high performance single seater that first flew in prototype form, designated KS-I, on 18 March 1963. It performed successful stalling and spinning trials that same day and was followed by a second prototype.
It was a single seat, high performance machine, fairly conventional apart from the wing planform of the first variant, the KS-I Kartik. Rather than the usual taper, its 15 m (49 ft 3 in) span, high, cantilever wing had inner and outer rectangular panels of different chord, 200 mm (7.9 in) narrower outboard. This approximated taper and was simpler to build with fewer different sized ribs. The mid-wing joins were blended with short tapered sections of the trailing edge; the leading edges were straight. Overall there was 1° of forward sweep. The wing structure was wooden, consisting of a single main spar with plywood skinning forward from it around the leading edge to form a torsion resisting box, a secondary rear strut and diagonal drag struts at the wing roots. Fabric covering was used aft of the main spar. The wing was mounted with 1.50° of dihedral. It was fitted with ply covered, wood framed ailerons and had wooden air brakes which opened above and below at mid-chord.
The Kartik's fuselage was a ply skinned, wooden framed semi-monocoque with an aluminium nose cap. The cockpit was ahead of the wing leading edge with a removable perspex canopy. Oxygen was an option. Aft, the fuselage tapered gently to the tail surfaces which were straight tapered and square tipped. Its tailplane, mounted at the top of the fuselage, was positioned forward of the fin so the rudder, which reached down to the keel, only required a small cut-out for operation. The fin and the tailplane leading edge were ply covered, the remainder fabric. The starboard elevator carried a trim tab.
Ramamrithram provided the Kartik with similar landing gear to that of his earlier Bharani: a fixed Palmer/Dunlop unsprung monowheel without a brake, a rubber sprung, steel shod forward skid and a tail skid with tennis balls as a spring. The pilot sits under a rearward opening hinged Perspex canopy, and oxygen equipment is optional.
Flight testing of the KS-I showed that the double rectangular wing was not a success and a third prototype, designated KS-II, first flew on 4 May 1965 and this had a conventional tapered wing to allow flight evaluation of the relative performances of the two wings; fabric-covered slotted wooden ailerons replaced the KS-l's plywood-covered wooden ones. Area and span remained the same, though the airbrake area increased. A wheel brake was added and maximum take-off weight increased by about 7%. Other changes in the KS-II included a slight increase in fuselage length (100 mm / 3.9 in and a reduction in cockpit height, and second, third, fourth and fifth prototypes of the KS-II were test flown during February 1967, March and May 1968 and May 1969, plus a sixth prototype in 1970.
The third and subsequent aircraft incorporated several improvements, including a reduction in fuselage height, now fitted with a rear hinged canopy, and larger air brakes, while the ninth KS-II Kartik, flown in 1976, has the air brakes replaced by trailing edge slotted flaps.
The KS-II was type certificated in 1965 and during the first Indian National Gliding Rally, held in 1967, the Kartik scored many successes, including setting a national speed record over a 200km (124 mi) triangular course.
First two prototypes, first flown 18 March 1963. Double rectangle wing.
First flown 4 May 1965. Straight tapered wing. Seven built.
Wingspan: 15.00 m (49 ft 3 in)
Height: 2.26 m (7 ft 5 in)
Wing area: 13.54 m2 (145.7 sq ft)
Aspect ratio: 16.6
Airfoil: NACA 643618
Length: 7.37 m (24 ft 2 in)
Empty weight: 210 kg (463 lb)
Max takeoff weight: 320 kg (705 lb)
Water ballast: None
Maximium wing loading: 23.63 kg/m2 (4.86 lb/sqft)
Maximum speed in smooth air: 200 km/h (124 mph; 108 kn)
Maximum speed in rough air: 140 km/h (87 mph; 76 kn).
Stall speed: 58 km/h (36 mph; 31 kn)
Max aero-tow speed: 71 mph
Maximum glide ratio: 31 at 75 km/h (47 mph; 40 kn)
Rate of sink: 0.6 m/s (120 ft/min) minimum, at 65 km/h (40 mph; 35 kn)