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Aviation History
1977
1977 - 0142.PDF
132 BRITAIN'S EXPORT AIRSHIP altitude makes reliable and accurate height information essential. A Bendix weather radar, is specified, and for homing a transponder on the mast provides range and bearing. Similarly, their relatively low speed can result in very large drift angles, and some form Of drift-meter will be fitted. For navigation Aerospace Developments will offer a VLF (very low frequency) package based on Omega. Maintenance of the ships will be farmed out to local operators, and other work such as crew training, flight operations and technical publications will also be placed locally. The British airship company has proposed a design for a servicing hangar, though good facilities already exist in Trinidad only 400 miles away, a relic of the USN airship days. The flight-test programme will be based on some 60hr flying. Originally 200hr had been estimated, but this has been cut on consultation with Goodyear. The test schedule is at present rather nebulous and will probably not be finalised until just before trials begin. Apart from perform ance (speed, rate of climb on static lift and under power, simulation of "hot and high" with reduced helium volume, and manoeuvrability) there will obviously be emphasis on emergency procedures such as maximum descent rates and engine-out performance. Smooth certification will depend heavily on the expertise of Belotti, Aerospace Develop ments' test pilot. In addition to his background with the US Navy and Goodyear noted earlier, Belotti was also involved with test-flying the Wiillenkemper airship in Germany. LEADING DATA: AEROSPACE DEVELOPMENTS TYPE 500 Length 164ft Maximum diameter 50ft Height overall 61 -5ft Max speed 62kt Fuel capacity 100 Imp gal Propulsion two Porsche three-litre six- cylinder air-cooled petrol engines of 200 h.p. (max) each, 150 h.p. (normal max cruise), 100-120 h.p. (normal cruise) Cruise speed 50kt Max rate of climb (200 h.p. rating each engine) 2,340ft/min Payload (exclusive of two crew and 100 Imp gal fuel) 2-56 tons (ISA, 2,000ft pressure height), 20 tons (ISA, 6,000ft pressure height), 2-1 tons (ISA +30°C, 2,000ft pressure height), 1 -6 tons (ISA +30°C, 6,000 ft pressure height) Range (10 per cent reserves) 300 n.m. Ferry range (with re-ballasting stops, 10 per cent reserves) 1,400 n.m. Patrol range (38kt) 600 n.m. Airships may have a big part to play in South America, where replacement for superannuated fixed-wing aircraft can cost up to fifty times as much as the original equip ment. Aerospace Developments estimates that transport- airship operators could charge $2/ton-mile, a figure which takes into account the money borrowed to purchase the ships at 5 per cent interest over ten years, and insurance premiums of ten per cent of cost price during the first year of operation. South America has some of the richest mineral and timber land in the world, and the economics of exploitation depend largely on accessibility. The cost of motorways is prohibitive in relation to the number of people served, while the rivers (even where they are navigable) are likewise limited. Natural resources more than 20 miles from river or road, although capable of returning perhaps 500 per cent on investment, are usually not worth the cost of transportation. The Aerospace airships will, of course, have nowhere near the performance needed to transport bulk materials, but their deployment in relatively large numbers as a result of the Aerovision initiative, says Wood, could bring about a climate of opinion favourable to the introduction of larger vehicles. Returning to the economics of the present airships, Wood estimates the total operating cost of an Aerovision vehicle at $300/hr, assuming an annual utilisation of 2,800hr. On this basis, he says, a ship will show a 20 per cent profit on advertising operations if it flies only 300hr/year. The Goodyear ships chalk up about 800hr/year on fair-weather publicity flights, and Wood says that the Aerovision ships will initially fly 1,000-1,500hr. The potential outlet for aerial advertising over Caracas and its suburbs is very large, so there should be no difficulty in showing accept able returns on advertising alone. Initial cost is £400,000 FLIGHT International, 15 January 1977 Dowty Rotol's ducted propulsor is a seven-blade variable-pitch fan unit enclosed in an aerodynamic, acoustically lined duct. Its main advantage over a ducted propeller are lower noise and the convenience offered by the reverse-thrust facility. Aerospace tells Flight that the advantages far outweigh the greater initial cost and mechanical complexity. In addition to its probable adoption on the airship, the Dowty unit is to be flown for the first time later this year on a modified Islander and estimated contract value of 22 ships is £13 million. Aerospace Developments reports interest by other companies and countries Surinam, for example, is exploring the possibilities of using airships for photo- surveys in support of mineral-prospecting, and South Africa is looking for economical maritime patrol air craft. Most important of all, perhaps, are the potential opportunities opening up around the coast of Britain, with the country's future prosperity largely tied up in the form of vast offshore oilfields, and with profitable fishing in the new 200-mile zones. The possibility of using airships to keep an eye on oil- rigs has been discussed by Britain's Ministry of Defence (incidentally reflecting the new level of credibility resulting from the CAA's pioneering certification work). Protecting these expensive, vulnerable and dispersed installations at reasonable cost during a time of international tension would be very difficult; at present maritime patrol aircraft such as Nimrod are employed. Airships, says Wood, would be ideal for surveillance; a military version of the Aero vision ship, with a crew of five and carrying a dunking sonar, could remain on station for 72hr, ready to summon RAF or Royal Navy armed support if necessary. Their relatively low transit speed of 60kt or so would be unim portant owing to the proximity of the rigs to land and the proportion of time spent on station compared with the transit time. Many of these rigs lie in the newly instituted 200-mile fishing zones declared by Britain, so to some extent airships could double up the duties. The coastal-patrol niche was the last stronghold of the previous generation of airships, and may provide the opportunity for a large-scale reintroduction of these vehicles. A few years ago America's Advanced Research Projects Agency conducted a survey of long-endurance maritime patrol aircraft, airships and surface vehicles such as hydrofoils. It came to the conclusion that, if the deci sion was taken to go for a completely new vehicle—not an adaption of an existing type—the airship would be superior. John Wood says that a maritime reconnaissance version of the Aerovision ship, with dunking sonar and a surface detection radar such as the Ferranti Seaspray, could be bought for about .£700,000, and its operating cost, compared with that of a Nimrod, would be perhaps an order lower. Such a project would call for only a small development programme. D
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