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Aviation History
1987
1987 - 0880.PDF
liberal time margins for contingencies. What the technicians cannot predict are financial surprises and the competition awaiting the project. These are the intan gibles which will doubtless permanently haunt the venture. It has been established that each part ner will finance its share of the work, and that transfer of knowhow has to be remu nerated. While there is no problem about full involvement of the Chinese Govern ment, the financing problem is left wide open for MBB, not to mention the risk- sharing partners which have yet to be found. General Electric is a prime candi date, but the content of its MoU with MBB is unknown. There is little doubt that MBB, even if it is responsible only for the financing of the 35 per cent share it wants in the venture, will need Government support in view of the magnitude of the project. For West Germany the MPC-75 is obviously politically and commercially desirable because it will help open up a wide market for German technical merchandise in China beyond that directly related to aviation. But, as with the Seastar, hopes that Government funds will be allocated are clouded by the fact that the Airbus venture—which is also a political necessity—is bound to soak up most of the budget earmarked for the support of the German aerospace indus try On the other hand, with its preparations for the MPC-75 project, MBB has handled the whole affair in a very clever way. By signing the MoU in Beijing, the company has not only committed itself, but also German industry's reputation. The Government will be hard pressed to extricate itself from that quandary— whether the budget is running dry or not. MTU shrouded propfan MTU has been watching developments at MBB with a slightly jaundiced eye, because the company has been working on a new-generation shrouded propfan pro pulsion system which might have been just right for the MPC-75. When MBB signed the MoU with General Electric there must have been some teeth-gnashing at MTU, which for decades had been a faithful partner of GE, but just on this novel system had decided to co-operate with Pratt & Whitney and Fiat. But MBB's attitude is also under standable. MTU's new engine design will only begin its first tests at Pratt & Whit ney in 1988, so it will come too late for inclusion in the MPC-75 schedule. Three years ago MTU began studies of a propfan engine which could serve as a fallback powerplant option for the Airbus A320, should the UDF-powered Being 7J7 become a success. Since the MTU design would be a direct competitor for the UDF, the company contacted Pratt & Whitney as a possible partner. There has been smooth co-operation ever since, and a joint venture is contemplated. MTU's design carries the name Crisp (counter-rotating integrated shrouded propfan). The company has developed a novel concept which promises to eliminate some of the well-known disadvantages of open propfan designs. These originate primarily with the excessive noise. This in turn forces the aircraft designer to strengthen the structure wherever the vibrations (both high and low frequency) impact on the airframe, and to provide sound-attenuating materials for protec ting the passengers. Under the aegis of a Ministry of Research and Technology-funded pro gramme, MTU conducted extensive computer studies during 1984/85, com paring a wide variety of contemporary propfan systems with turbofans. The results indicated that the fuel savings achieved by the use of open propfans are virtually negated by the additional weight of structural changes and sound-attenua tion measures. Essentially, the studies indicated only marginal operational advantages for the open propfan over the latest generation of turbofans. On the basis of these studies MTU decided to embark on the develop ment of the Crisp shrouded propfan. Crisp has a bypass ratio of 25:1 (lower than that of propfans) because the shroud permits the full aerodynamic utilisation of the fan tips. In turn, this allows the fan diameter to be shrunk to almost half that of an open propfan, while achieving iden tical thrust performance, according to MTU. The Crisp blades have variable and reverse pitch. The low-drag shroud is considerably shorter than the shrouds of current turbofans. The estimated noise levels are low enough to permit cabin comfort compara ble with that of turbofan-powered aircraft, without the necessity for extra noise protection It is expected that Crisp will comfortably meet FAA noise regulations, and will thus allow operation out of Wash ington National. The shroud would contain any separated fan blades, which solves a problem yet to be answered for open fans. Also of importance for the future is the fact that, like turbofans, Crisp designs are not Mach-limited, whereas the open propfan seems to be limited to about Mach 0 • 75. Current planning among MTU, Pratt & Whitney, and Fiat envisages the construc tion of a Crisp demonstration powerplant using a PW3005 core, provided a tech nology feasibility programme scheduled for next year yields promising results. Crisp models are being tested in wind- tunnels in Germany and at UTC's research centre in the United States. The technology needed for the HP and trans onic LP turbines, transmissions, pitch- change gears and shroud is being explored, and initial design work conducted. The development target is for engine certification in the mid-1990s. Inci dentally, a "crisped" PW3005 core engine would be of just the right size and thrust for the MPC-75 Sino-German airliner, providing an alternative to UDF. Dornier 328 Dornier unveiled its latest aircraft project, the Do.328 regional airliner, last month, and a full-scale cabin mockup is being displayed at the Paris Air Show. The Do.328 represents a logical continuation of the Do.228 commuter concept, which has achieved considerable worldwide sales success during the past years. The Do.328 is planned as a pressurised turboprop twin offering comfortable 31in-pitch seating for 30 passengers. One of the design's prime goals has been cabin comfort. The fuselage is cleanly circular, with a diameter of 8ft, which not only gives adequate headroom but permits three-abreast seating in an environment not unlike that found in larger airliners. The planned range is 700 n.m. (including reserves) at a cruising speed of 300kt. Runway lengths of less than 3,000ft should suffice for normal operations, but the Do.328 will also be able to operate from gravel runways if necessary. With the exception of a T-tail, the aircraft cannot hide its close aerodynamic relationship to the Do.228. Its wing and undercarriage arrangements are virtually enlarged versions of the proven design, but here the similarity ends. Some 50 per cent of the airframe will be built of traditional aluminium alloys, but a further 24 per cent will be of aluminium- lithium alloys, and 19 per cent of various composites. This mix will yield weight savings of more than 4001b. The power- plant will be two 1,700 s.h.p. turboprops driving four-bladed propellers of a new design. Dornier has not decided which engine type will be used, but talks are under way with Garrett, General Electric, and Pratt & Whitney. The first flight could take place by 1990, with first customer deliveries in 1992, provided adequate funding becomes avail able. Three prototypes will be built, plus two airframes for static testing. Dornier claims that up to 500 aircraft can be sold by the year 2005 at about $5 million each in 1986 values, at up to 35 aircraft per year. Development costs are estimated to be DM700 million plus DM60 million for equipment and subsystems by other manufacturers. Financing support has been requested from the Ministry of Commerce, and Dornier counts on a positive decision despite Airbus financing problems. But realisation of the Do.328 project depends on the amount of funding needed for continuation of the A330/340 programme. Bane and blessing It is clear that the Airbus venture is indeed both a bane and a blessing for the German aerospace industry, depending from which side it is viewed. The task of the decision makers with the power to pour the budget into the manufacturers' empty purses is not easy. They can support many of the smaller, promising projects with sums which are adequate to meet their most urgent needs, thereby permitting only marginal pro gress. Alternatively, they can select a few of these ventures, support them lavishly, and run the risk of betting on the wrong horse. Or they can give a lion's share of funds to a major programme and distri bute the leftovers to those firms who have the best lobby. But having the best lobby does not necessarily mean being able to build the best aircraft. E 118 FLIGHT INTERNATIONAL, 13 June 1987
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