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Aviation History
1959
1959 - 1053.PDF
512 FLIGHT One of the most Im- portant new helicop- ters, the Sud 3.200 is planned for inter-city work with up to 30 passengers, military missions of all kinds and shipboard tasks such as ASW patrol or minesweeping. The specification given be- low has not previously been published Hew French Helicopters A HELICOPTER ASSOCIATION LECTURE AN informative paper entitled French Helicopter Develop- /^ merits, by M. F. L. Legrand, chief engineer of Service •L •*• Technique Aeronautique, was read in the R.Ae.S. librarybefore the Helicopter Association on April 10 by Mr. A. McClements. M. Legrand began by saying that in France, as elsewhere, theArmed Forces were by far the largest users of helicopters, there being several hundred in operation by the Air Force, Army andNavy. All helicopter research and manufacture was carried out by Sud Aviation, but two other firms deserved mention: theSoc. Giravions Dorand, which specialized in helicopter flight simulators, and the Soc. Heli-Service, responsible for the main-tenance of the Vertol H-21 and the Djinn. Last year the total number of helicopters delivered by Sud cost some £6m, or about13 per cent of the company's gross output. He went on to examine the characteristics of the Sud'Djinn,the only tip jet helicopter so far built in large numbers. Among its attributes were the ability to fly for 5 sec on the rotor's storedk.e., to use the jump technique to achieve certification at overload weights and to carry a payload representing 54 per cent of thegross weight. M. Legrand then turned to the Sud Alouette II, driven by a Turbomeca Artouste single-shaft engine of 360/400 h.p. The primary objection to the fixed-shaft turbine was possibler.p.m. instability. In practice, this risk was present only when a temperature regulator was used for power control, and wasavoided if the turbine was controlled either by the fuel supply or by a speed governor such as was used in the Alouette. One of thegreat practical advantages of the last-mentioned was that no throttle control was needed; the pilot only had to actuate thecollective-pitch lever, while the governor automatically looked after rotor r.p.m. Some precautions were necessary in designing the governor;it had to prevent too considerable a drop in rotor r.p.m. when sudden additional power requirements were imposed, and carehad to be taken lest at some settings it induced sustained torsional oscillations of the rotor/transmission/turbine assembly. The fixed-shaft turbine was also prone to overheating and compressor surg- ing. Some cases of these troubles were experienced when theAlouette first went into service, owing to the fact that the pilot had no practical means of knowing, for any given flight condition,the power limitations not to be exceeded. The problem was solved by ensuring that pilots complied exactly with operational limita-tions, particularly with regard to weight/altitude/temperature conditions. Further, it was shown that the collective-pitch indica-tor always provided a sufficiently accurate indication of the power 77ie Alouette III, first flown last month, will hove much better weight/ altitude I temperature performance than its well-known predecessor absorbed by the rotor compared with the safe power available (andso became the most important flight instrument). As an additional safeguard, the collective-pitch lever had been fitted with an elasticstop, which could be passed in emergency. Overhaul life of the Artouste II was originally 200 hr; it now stood at 350 hr, shouldreach 750 hr soon and 1,000 hr later. Sud had actually had an Alouette fitted with a free-shaft Turmo, but it showed nosignificant advantages. An incidental feature of both the Djinn and the Alouette was theuse of pneumatic equipment. Considerable weight savings had been effected by the use of bleed air to operate blind-flying instru-ments, fuel gauges, cabin heaters and de-misters, trimmers, air/sea rescue hoists and crop-spraying equipment. The lecturer concluded by giving some details of new helicoptertypes at present under development. These were the Djinn III, the Alouette III and the Sud 3.200. The Djinn III was planned tobe an improved version of the Djinn with greater power and endur- ance. The Alouette III had been undergoing flight testing sincethe beginning of March. Although the first was powered by an Artouste III, of 500/550 h.p., later versions would have an ArtousteIIIB of 700/750 h.p. The additional power would provide an increased payload of seven passengers or two stretcher cases andthree passengers. Normal freight load would be nearly one ton. Awaited with intense interest, the third new type, the Sud 3.200,was much larger and was powered by three coupled free-turbine engines. Turbomeca Turmo IIIB units of 750/800 h.p. wereinstalled at present, but the production version would have Turmo IIICs of 1,000/1,100 h.p. (but limited to 900 h.p. for normal opera-tion). Access to the cabin was by means of two sliding doors, two floor traps were provided for military missions, and the completetail could be folded for bulky loads. The fuel nacelles on either side of the fuselage were jettisonable and, to avoid corrosion, nomagnesium alloy was used in the primary structure. The three turbines were mounted above the cabin, two side-by-side forward of the pylon and the third behind. When cruising on two engines, the improved range was considerable. In addition tolaboratory testing, a full scale endurance test rig was built to repro- duce the engine installation, transmission and rotor systems. Thishad been in operation since last August; exhaustive ground testing had already been carried out, but the rig would remain in use fora long time to come. The first prototype was completed early this year and was being subjected to intensive ground running. Testingof the second prototype was due to start very shortly. SUO ALOUETTE III Turbom»ca Artouste IIIB rated at 700/750 s.h.p. Dimensions: main rotor, three blades, diameter 36ft; tail rotor, three blades, diameter 6ft: overall length (blades folded), 33ft 2in; overall width (folded), 8ft 6in; height, 9ft 8in. Weights (standard 7-seater with v.h.f. radio and rotor brake): normal gross. 4.200 Ib (disc loarfina, 4.1 Ib/sa ft); overload, 4,630 Ib; empty, 2,300 Ib: useful load, 1,900 Ib (2.330 Ib overload). Performance (normal aross weight, I.C.A.N. standard day): hovering ceiling, 9.840ft (12,300 in ground effect); service ceiling, 13.100ft; max. speed at sea level, 124 m.p.h.; -ruisinq speed at sea level, 118 m.p.h.: cruising fuel consumption, 3 Ib/st. mile; extreme altitude operation, take-off and landing with 550 Ib payload, 19,650ft. SUD 3.200 (Design figures for prototypes) Three Turbom»ea Turmo IIIB free-turbines rated at 750/800 s.h.p. each (pro- duction version, Turmo IIICs at 1,000/1,100 h.p.). Dimensions: main rotor, four blades, diameter, 49ft 1^in; tail rotor, four blades, diameter 8ft 2iin.: overall length (blades folded), 48ft 10^in; overall width (folded), 17ft 1in; heiaht (folded), 15ft 5in. Weiahts (standard version, with radio and naviaation systems): normal gross. 16,535 Ib (disc loadina, 8.6 Ib/sq ft); overload, 17,640 Ib; empty, 9,920 Ib; useful load, 6,614 Ib (7,716 Ib). Performance (normal aross weight, I.C.A.N. standard day): hovering ceiling, 1.640ft (5,900 in ground effect); service ceiling, 10,830ft: max. speed at sea level, 159 m.p.h.; (cruising speed at sea level, 149 m.p.h. (130 m.p.h. on two engines); low-altitude cruising fuel consumption, 8.15 Ib/st. mile (7.1 Ib on two engines); max. range with normal fuel (660 Imp. gal), 621 st. miles (745 miles on two engines).
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