page_title: Saab 29 Tunnan
section_title: Development
hierarchical_section_title: Saab 29 Tunnan / Development
caption_attribution_description: English: Saab S 29C Tunnan on permanent display at the Swedish Air Force Museum in Linköping, Sweden Svenska: Saab S 29C Tunnan, flygplan 29970, levererades den 19 januari 1956. Det flög som fotospaningsflygplan vid F 11, F 21 och från år 1967 vid målflygdivisionen F 3. Flygplanet hade tjänat ut den 30 juni 1970, och överlämnades därefter till de flyghistoriska samlingarna på Malmen.
context_page_description: The Saab 29, colloquially called Flygande tunnan, is a Swedish fighter that was designed and manufactured by Saab in the 1940s. It was Sweden's second turbojet-powered combat aircraft, the first having been the Saab 21R; additionally, it was the first Western European fighter to be produced with a swept wing after the Second World War, the Me 262 having been the first during the war. Despite its rotund appearance, from which its name derives, the J 29 was a fast and agile aircraft for its era. It served effectively in both fighter and fighter-bomber roles into the 1970s.
context_section_description: In the aftermath of the Second World War, Sweden required a strong air defence utilising the newly developed jet propulsion technology. According to aviation author Bo Widfeldt, there was a perception that Sweden had not kept up with wartime innovations and technical progress, and that Saab was eager to make aeronautic advances, particularly in terms of developing jet propulsion. Accordingly, project "JxR" was initiated in the final months of 1945, leading to the requirements being drawn up in October 1945. This led to a pair of proposals being issued by the Saab design team, led by Lars Brising.  The first of these, codenamed R101, was a cigar-shaped aircraft which bore a resemblance to the American Lockheed P-80 Shooting Star.  The second design, which was later picked as the winner, was the barrel-shaped design, codenamed R 1001, which proved to be both faster and more agile upon closer study.
  The original R 1001 concept had been designed around a mostly straight wing, but after Swedish engineers had obtained German research data on swept-wing designs, the prototype was altered to incorporate a 25 degree sweep. Information on swept-wings came from Switzerland and included drawings on Messerschmitts Messerschmitt P.1101, Messerschmitt P.1110, Messerschmitt P.1111 and Messerschmitt P.1112. SAAB's project manager Frid Wänström retrieved these secret papers from Switzerland to Sweden in 1945. The documents came from engineers from Messerschmitt who fled to Switzerland at the end of the Second World War. Among them were the engineer and aerodynamicist Hermann Behrbohm, who came to be part of Saab's core in the team around J29 and upcoming aircraft types. These files had clearly indicated delta and swept-wing designs to have the effect of "reducing drag dramatically as the aircraft approached the sound barrier." In order to make the wing as thin as possible, Saab elected to locate the retractable undercarriage entirely within the aircraft's fuselage, dispensing with the main gear retracting into the wings.
  Extensive wind tunnel testing performed at the Swedish Royal University of Technology and by the National Aeronautical Research Institute had also influenced aspects of the aircraft's aerodynamics, such as stability and trim across the aircraft's speed range. These tests had determined the required slenderness of the fuselage in order to ensure compatibility with the targeted critical Mach number, as well as supporting the use of a straight-through airflow system to ensure the maximum attainable thrust, in addition to the advantages of its ease of development. For the reason of lateral stability during take-off and landing, automatically-locking leading edge slots, which were interconnected with the flaps, were also deemed necessary. In order to further test the design of the swept wing, it was decided to modify a single Saab Safir, which received the designation Saab 201, with a full-scale wing for a series of flight tests.  The first 'final' sketches of the aircraft, incorporating the new information, was drawn in January 1946.
  The originally envisioned powerplant for the type was the de Havilland Goblin turbojet engine. However, in December 1945, information on the newer and more powerful de Havilland Ghost engine became available. This was deemed to be ideal for Saab's in-development aircraft as not only did the Ghost engine have provisions for the use of a central circular air intake, the overall diameter of the engine was favourable for the planned fuselage dimensions; thus, following negotiations between de Havilland and Saab, the Ghost engine was selected to power the type instead.
  Despite early doubts over the availability of a suitable aluminium alloy, similar to the American 75S alloy, Svenska Metallverken was able to manufacture the sufficient grade of sheet metal, equivalent in strength to its US-based counterpart, albeit requiring the use of significantly larger sections than had typically been employed in aircraft construction. The structure employed a complicated mixture of stressed skin and heavy frames i
caption: SAAB S 29C 'Tunnan' on display at Swedish Air Force Museum, Linköping
exif: {"Image Copyright": "Stefan Sjogren"}