Sweptforward Wings for the HFB 320 Hansa: An Outline of the Design Considerations which Led to the Adoption of Sweptforward Wings for the Hamburger Flugzeugbau Hansa Jet Executive Aircraft

IN 1955 Hamburger Flugzeugbau began to reconstruct its Finkenwerder plant and develop its aeronautical activities, following the period of in‐activity after the Second World War. Production began with an order from the West German Federal Defence Ministry for components for the S.N.C.A.N. 2501 Noratlas built under licence for the West German Air Force. Final assembly and flight testing of this twin‐engined transport were also carried out at Finkenwerder. The next stage of development involved participation in the European licence production of the Lockheed F.104G Starfighter, and in the design and construction of the Franco‐German C.160 Transall transport. By J 958, HFB had completed the project stage of the design of a turbojet airliner—the HFB 314. This was a short /medium‐range airliner designed to carry 70 tourist class passengers over ranges up to 1,250 miles. Although Hamburger Flugzeugbau had designed the aircraft in close co‐operation with Lufthansa, West Germany's largest airline, and were fully prepared to produce the aircraft in consort with other German or European companies, development costs would have amounted to some £5 million and since no Government financial support was forthcoming, the project was abandoned. Determined to reassert its authority as a design agency, HFB turned to the jet executive field in 1960 and designed the twin‐jet HFB 320 Hansa. The most distinctive feature of this aircraft is without doubt its sweptforward wing and it is this feature which is dealt with in detail in this article. The decision to utilize such a wing was based to some extent on Hamburger Flugzeugbaus‘ technical experience in the development of the Junkers Ju 287 sweptforward wing dating back to the Second World War. The HFB 320 Hansa is powered by two General Electric CJ 610–1 turbo‐jets, each of which has a weight of 355 lb. and a thrust of 2,850 lb. The engine's eight‐stage axial compressor has a mass flow of 565 at. ft. I sec. at 16,500 r.p.m. At gross weights of 16,000 to 18,000 lb., the Hansa will cruise at 500 m.p.h. over ranges up to 1,600 miles with full reserves. Well over 2,000 hours of model testing have been carried out in wind tunnels at the Aerodynamische Versuchsanstalt, (Goettingen), National Luchten Ruimtvaartlaboratorium (Amsterdam), Torrejon (Madrid), Emmen (Switzerland) and Modane (France).‐ Static testing is underway on an airframe structural specimen including: test for maximum cabin pressure, windshield strength test—bird impact, investigation of ground and landing loads, and investigation of loading at the extremes of the flight envelope. Later this summer, HFB will commence a programme of loading tests of a dynamic test airframe utilizing the water tank technique, involving pressurization cycles and gust loading to simulate 50,000 flights. Assembly of the first prototype HFB 320 Hansa was completed on March 18, 1964, and was followed by ground resonance tests, and engine ground’ running prior to the aircraft's maiden flight on April 21. The prototype, which carries extensive flight test instrumentation and is not equipped with the production‐type cabin, made its first public appearance at the Deutsches Luftfahrtschau at Hanover‐Langenhagen a few days later. The full flight test programme is currently being pursued.