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Aviation History
1958
1958-1- - 0933.PDF
19 December 1958 941 Gdttingen University) was preparing schemes for both side-by- side and tandem arrangements; the controversy rages as hotly in India as in Europe or America. Vision in formation flying, and for the instructor when landing, and e.g. changes, are design-cases that must be met, but the final decision will generally depend upon current views on instructor-pupil psychology. To a half-serious suggestion that a staggered-seat layout should be adopted, Dr. Ghatage replied that it had, in fact, been investigated and "wasn't a bad compromise." If the aeronautical engineer has a preference it is likely to be for a tandem arrangement and a slim fuselage; that way a better performance can be obtained from a given power unit. Which engine will be chosen in the case of the Hindustan Trainer (the provisional designation of which is HJT-16) is as yet undecided, but Armstrong Siddeley Viper, Turbomeca and Rolls- Royce RB.145 units have all been considered. It has been reported that under the direction of Dr. Kurt Tank, the German engineer responsible for the formidable Fwl90, Hindustan are developing a fighter. It is interesting to speculate on the form that the first fighter to be born in the tropics might take, particularly since many of the factors that must govern the design are known. It is not practical, for example, for India to attempt to compete with the United States, England or Russia in a race for ultimate performance; but higher-thrust versions of the Orpheus with reheat, such as the BOr. 12, could be manufactured in India under an extension of the licence agreement (Hindustan know-how on the Orpheus would appear to make this a logical, although not obligatory, choice). The combined thrust of two reheat Orpheus could certainly give the new fighter a performance substantially better than that of anything at present flying in India. Preparation for more advanced designs is also continuing in other directions as well: at Bangalore, for instance, H.A.L. are extending their runway. One aircraft for which this extension will be of little conse- quence is the Pushpak, India's first light touring aircraft, built by H.A.L. as a private venture (something of a contradiction in a nationalized company?). The prototype, VT-XAA, is finished in blue and red, and has recently been on display at the "India 1958" exhibition in Delhi, where it attracted much attention. Indeed, Hindustan have been almost embarrassed by the interest that the little two-seater has excited; it is understood that the Board has still not unanimously decided to go ahead with the project. If it does so (the managing director, A.V-M. A. M. Engineer, seems keen that it should) then a separate division of the company will be formed in order to divorce the Pushpak production from general works overheads; a low selling price is most important, and it is aimed to retail the aircraft at about Rs 20,000 (£1,540). Running costs should not exceed about 30s per hour. The first aircraft was built, by hand, in less than six weeks and a second machine is now being constructed in the same ultra- simple jigs as the prototype. The two aircraft differ mainly in the choice of wing-spar material: a largish stock of imported spruce provided the wooden spar of the first prototype, but so much difficulty was encountered in selecting suitable shake-free lengths of timber that all subsequent aircraft are to have a new design of metal spar supporting the pressed light-alloy ribs. Construction is extremely simple. The fuselage is formed from a triangulated framework of welded steel tubing; two sides are tack-welded on a baseboard jig and the third (lower) side of the three-cornered frame is added in the welding jig. The Pushpak bears a superficial resemblance to an Auster, but a slightly more sophisticated fuselage cross-section has been adopted. This is formed by light wooden bulkheads carrying wood stringers, the whole being covered with fabric. Tailplane, fin and rudder are constructed entirely from steel tube and are of constant thickness with zero camber. A few castings (from the extensive H.A.L. foundry) are used in the construction—e.g., for the rudder pedals —but most fittings are fabricated from welded steel sheet. Power unit of the first few Pushpaks (probably the first 20) will be the 85 b.h.p. flat-four Continental. But from the twenty-first aircraft onwards it is intended to offer the Pushpak as the first all-Indian aeroplane powered by the first engine of Indian design The Pushpak's dual controls are kept deliberately simple. Prototype instruments are of American origin, overhauled and with re-calibrated dials. There is side-by-side seating for two "Flight" photograph and manufacture. This is now being constructed by H.A.L. at Bangalore. An air-cooled flat four, the Indian design has attempted to combine the best of Continental and Lycoming engine practice. Progress is encouraging. At the time of my visit last month the crankcase top and bottom halves were complete and had been line-bored, connecting rods had been machined, valves had been turned from valves of larger size and experiments were being undertaken to determine the correct interference between the screwed light-alloy cylinder barrels and their steel sleeves. The camshaft and crankshaft were complete, the billet for the latter having been rough-forged to establish the grain flow and subsequently extensively machined. Every sort of pitfall, foreseeable and unforeseeable, besets the designer of an aero-engine, but in this case Hindustan's "learn slowly" policy seems sensibly cautious, and a ready market should await an American-type engine of this kind in a dollar-starved South-east Asia and elsewhere. The Pushpak was completed just in time to be test flown (on September 24) before the opening of the "India 1958" exhibition in Delhi, where it appeared on an open-air stand of its own. It was flown up to Delhi and is reported to be very easy to handle. In the cockpit are two control spectacles; pedals with differential toe-brakes; push-pull throttle; fuel primer; and carburettor heat control. There are no flaps and no parking brake, and the cockpit is kept as simple as possible. A fire extinguisher is fitted and the bench-seat is adjustable; radio can be fitted in the luggage com- partment behind the seat, access to which is from the cockpit. Instruments (A.S.I., altimeter, compass, bubble slip-indicator, r.p.m., oil temperature and pressure) are of American origin, actually stockpiled instruments that have been adjusted and equipped with re-calibrated dials. Ailerons are of the Frise type and are differential in operation. Performance figures quoted were: maximum speed 115 m.p.h., cruising speed 86 m.p.h., and stalling speed 35 m.p.h. Although described as an ultra-light, the Pushpak weighs 872 lb empty and may be loaded to a maximum weight of 1,350 lb. The prototype has not been in any way specially finished and did in fact bear signs of rather rapid completion and rigging for the exhibition. Hindustan say that they are more than willing to make design changes in the light of demonstration criticisms and experience, and it is intended to bring a Pushpak to Great Britain as soon as possible. Enquiries for it are already coming in; one flying club has asked for five and there has been a surprising demand from tea planters and others in isolated communities. As outlined above, Hindustan's range of effort embraces over- haul, assembly, construction and design of almost all types of aircraft, and includes the maintenance of one helicopter, an S-55 In some of this work, the company already has considerable experience, and the constructional standard achieved on H.A.L.'s assembly lines is high. Where local experience is limited, the company is expanding cautiously, adopting a step-by-step tech- nique of a kind that might have been the salvation of more ambitious projects elsewhere around the world. Here and there— in the construction of the engine shop, perhaps in the tackling of two new designs at once—bold steps forward are being taken. Repeated all over India, this is the process of the country's industrial and national resurgence. To the Indian nation the part played by H.A.L.—favoured child of a tautly-stretched economy— is a very important one indeed. Indian Industry—2 HANDLING THE HT-2 ^LTHOUGH the Hindustan HT-2 basic trainer has now been £\ flying for some years, and is in service in quantity with the -L -A. Indian Air Force, it has yet to become we'l known outside South-east Asia and Australia. In the absence of first-hand know- ledge it has frequently been described as "an Indian Chipmunk"; and in view of the widespread occurrence of this little animal in India, Chipmunk might not have been a bad name for the HT-2. As it is, the Hindustan company's product has noi been named and is known only by its type number. It will certainly bear comparison with the Chipmunk, but it is not against its Canadian counterpart that it should primarily be judged. The HT-2 is the first aircraft of Indian design to go into production, the first Indian aircraft ever to receive a certificate to fly and the first indigenous design to be adopted by the Indian Air Force for operation under quite rigorous local conditions. The I.A.F. are generally very satisfied with their purchase and the aircraft is now also in service with various flying clubs; several having been purchased by the Indian civil aviation authority for airline pilot training.
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