Civil Aviation Department Ashvini

Last updated
Ashvini
RoleTwo seat trainer glider
National origin India
ManufacturerCivil Aviation Department
DesignerS.Ramamritham
First flight3 September 1958
Number built15

The Civil Aviation Department Ashvini was the first two-seat glider designed and built in India. It was produced in small numbers in the early 1960s.

Glider (sailplane) type of glider aircraft used in the sport of gliding

A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding. This unpowered aircraft uses naturally occurring currents of rising air in the atmosphere to remain airborne. Gliders are aerodynamically streamlined and are capable of gaining altitude and remaining airborne, and maintaining forward motion.

India Country in South Asia

India, also known as the Republic of India, is a country in South Asia. It is the seventh largest country by area and with more than 1.3 billion people, it is the second most populous country as well as the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west; China, Nepal, and Bhutan to the northeast; and Bangladesh and Myanmar to the east. In the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives, while its Andaman and Nicobar Islands share a maritime border with Thailand and Indonesia.

Contents

Design and development

Ashvini is the first nakshatra, a lunar based division of the ecliptic in Hindu astrology. The glider named after it was the first Indian two seater, [1] developed for the Indian Civil Aviation Gliding Centres and the National Cadet Corps. [2] The first prototype, the TS-2 Ashvini, was first flown on 3 September 1958 [1] by F.H. Irani and later in its development by the very experienced glider pilot Hanna Reitsch. [2] It was displayed to Prime Minister Nehru at Delhi Airport in February 1959. [3] The reports of both pilots led to improvements incorporated in the next three pre-production prototypes, [2] termed TS-3 Ashvini, along with some alterations made to ease later production. The first TS-3 flew in July 1959. The series production aircraft, first flown in prototype form in December 1960, was named the TS-4 Ashvini II. Alterations included revised forward fuselage contours and changes to control runs in the cockpit which allowed seats and sills to be lowered, easing access. The lift to drag ratio was increased by lowering the wing relative to the fuselage, improving the aerodynamics of the junction. Eleven production TS-4s were built. [4]

Ashvini first nakshatra (lunar mansion) of Hindu astrology

Ashvini is the first nakshatra in Hindu astrology having a spread from 0°-0'-0" to 13°-20', corresponding to the head of Aries, including the stars β and γ Arietis. The name aśvinī is used by Varahamihira. The older name of the asterism, found in the Atharvaveda and in Panini (4.3.36), was aśvayúj, "harnessing horses".

Nakshatra is the term for lunar mansion in Hindu astrology and Indian Astronomy. A nakshatra is one of 28 sectors along the ecliptic. Their names are related to the most prominent asterisms in the respective sectors.

Ecliptic apparent path of the Sun on the celestial sphere

The ecliptic is the mean plane of the apparent path in the Earth's sky that the Sun follows over the course of one year; it is the basis of the ecliptic coordinate system. This plane of reference is coplanar with Earth's orbit around the Sun. The ecliptic is not normally noticeable from Earth's surface because the planet's rotation carries the observer through the daily cycles of sunrise and sunset, which obscure the Sun's apparent motion against the background of stars during the year.

The Asvini had an all-wood structure, covered with a mixture of plywood and fabric, using Indian grown spruce and cedar. Its three part wing had two spars and 4° of forward sweep at the quarter chord line. The centre section had a span of 6.10 m (20 ft 0 in) and the outer panels were detachable. [4] In plan the wing was straight tapered (taper ratio 0.41), with forward sweep on both leading and trailing edges. [1] It was ply covered forward of the rear spar around the leading edge, forming a torsion box, and fabric covered over the remaining 30% of chord. Its high cantilever wing was mounted with 1° dihedral on top of the spar. [1] [4] It had plain fabric covered ailerons and short DFS-type air-brake pairs placed behind the forward spar at about one quarter span. [1] [5] There were no flaps. [1]

Plywood manufactured wood panel made from thin sheets of wood veneer

Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured boards which includes medium-density fibreboard (MDF) and particle board (chipboard).

Aircraft fabric covering

Aircraft fabric covering is a term used for both the material used and the process of covering aircraft open structures. It is also used for reinforcing closed plywood structures, the de Havilland Mosquito being an example of this technique, and on the pioneering all-wood monocoque fuselages of certain World War I German aircraft like the LFG Roland C.II, in its wrapped Wickelrumpf plywood strip and fabric covering.

Spruce genus of plants

A spruce is a tree of the genus Picea, a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. Spruces are large trees, from about 20–60 m tall when mature, and have whorled branches and conical form. They can be distinguished from other members of the pine family by their needles (leaves), which are four-sided and attached singly to small persistent peg-like structures (pulvini) on the branches, and by their cones, which hang downwards after they are pollinated. The needles are shed when 4–10 years old, leaving the branches rough with the retained pegs. In other similar genera, the branches are fairly smooth.

The Ashvini's fuselage was a ply covered wooden-semi-monocoque including an integral, ply covered fin with a straight, swept leading edge. Its balanced rudder, full and rounded, extended down to the keel. The horizontal tail was straight edged and double tapered, with square tips. It was mostly fabric covered apart from the leading edge and root and was placed on top of the fuselage, far enough forward that the inner edges of the separate elevators were in line with the rudder hinge. The rear control surfaces were fabric covered. [1] [4]

Monocoque Structural design that supports loads through an objects external skin

Monocoque, also structural skin, is a structural system where loads are supported through an object's external skin, similar to an egg shell. The word monocoque is a French term for "single shell" or "single hull". First used in boats, a true monocoque carries both tensile and compressive forces within the skin and can be recognised by the absence of a load-carrying internal frame.

Fin flight control surface

A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.

Balanced rudder

Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevators and ailerons; all three aircraft control surfaces may also be mass balanced, chiefly to avoid aerodynamic flutter.

Pupil and instructor, provided with dual controls, sat in tandem ahead of the wing leading edge, the latter at the rear over the centre of gravity. They had separate perspex canopies; the forward canopy was side hinged and the instructor's opened rearwards. The main landing gear was a single, non-retractable wheel without brakes. Ahead of the wheel and under the cockpits was a rubber sprung, steel shod skid and at the rear there was a short, tennis ball sprung tail skid. [4]

Tandem arrangement in which people, machines, or animals are in line behind one another facing forward

Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction.

Aircraft canopy

An aircraft canopy is the transparent enclosure over the cockpit of some types of aircraft. An aircraft canopy provides a controlled and sometimes pressurized environment for the aircraft's occupants, and allows for a greater field of view over a traditional flight deck. A canopy's shape is a compromise designed to minimize aerodynamic drag, while maximizing visibility for pilots and other crewmembers.

Variants

Data from Jane's All the World's Aircraft 1964/5 [4]

TS-2 Ashvini
First prototype, first flown September 1958.
TS-3 Ashvini
Pre-production prototypes with modifications to ease production and as a result of prototype flight testing. First flown July 1959; three built.
TS-4 Ashvini II
Production version with further improvements: forward fuselage and cockpit revised for easier access and wings lowered to improve wing-fuselage junction aerodynamics. First prototype flew December 1960 followed by eleven production models built by Aeronautical Services Ltd; production ended 1963.

Specifications (Ashvini II)

Data from Jane's All the World's Aircraft 1964/5 [4]

General characteristics

Performance

  • Maximum speed: 216 km/h (134 mph; 117 kn) placard, smooth air; rough air 75 mph; 65 kn (120 km/h)
  • Stall speed: 48 km/h (30 mph; 26 kn)
  • Never exceed speed: 222 km/h (138 mph; 120 kn) in dive
  • Maximum glide ratio: best, 23 at 48 mph; 42 kn (77 km/h)
  • Rate of sink: 0.82 m/s (161 ft/min) minimum, at 36 mph; 31 kn (58 km/h)


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References

  1. 1 2 3 4 5 6 7 Shenstone, B.S.; Wilkinson, K.G. (1958). The World's Sailplanes — Die Segelflugzeuge der Welt — Les Planeurs de le Monde (in English, German, and French). II. Organisation Scientifique et Technique International de Vol à Voile (OSTIV) & Schweizer Aero-Revue. pp. 134–6.
  2. 1 2 3 Taylor, John W R (1960). Jane's All the World's Aircraft 1960-61. London: Sampson Low, Marston & Co. Ltd. p. 366.
  3. ↑ "Sport and Business". Flight . Vol. 72 no. 2616. 13 March 1959. p. 368.
  4. 1 2 3 4 5 6 7 Taylor, John W R (1964). Jane's All the World's Aircraft 1964-65. London: Sampson Low, Marston & Co. Ltd. p. 366.
  5. ↑ "Asia's Aircraft Industry". Flight . Vol. 82 no. 2985. 26 July 1962. p. 135.
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