The Dornier aircraft manufacturer was founded in Germany back in 1914 by the German aircraft designer Claudis Dornier. The company became famous for the production of flying boats and various bombers for the Luftwaffe. After the end of the Second World War, the company engaged in the production of aircraft for private use, resuming its activities in the 1949 year in Spain. One of the successful post-war developments of the company was rightly considered a light multipurpose aircraft Do 27, which was mass-produced from 1956 to 1965 year, in total 628 aircraft of this type were produced. Do 27 was a high-grade all-metal, which could take on board up to 6 people (crew member 1-2 and 4-5 passengers) or up to 650 kg of various cargoes, depending on the modification.
Back in the years of the Second World War, Heinrich Fokke expressed the idea that the use of rotary pushing propellers to increase lift would help create a short take-off and landing aircraft. To implement this concept in practice prevented the war. However, already in the 1950-ies, due to the high interest in the idea of creating a shortened take-off and landing aircraft, the German military returned to the idea expressed by Heinrich Focke.
Given the rich experience of Dornier in creating aircraft for various purposes, it is not surprising that the German Ministry of Defense commissioned this company in close cooperation with the German Aeronautical Research Center (Deutschen Versuchsanstalt für Luftfahrt eV) to work on an experimental aircraft with a short take-off and landing . As part of the implementation of this program in Germany at the end of 1950-s, two flight samples of the aircraft, designated as Do 29, were built. The machines received two Lycoming GO-480 piston engines each, equipped with Hartzell pusher screws rotating in opposite directions.
The plane was created to solve a very specific range of tasks. Its main purpose was to become a comprehensive study of the problems that were associated with short take-off and run at the time of take-off and landing of the aircraft. In the future, it was supposed to design such a universal aircraft, which could be launched into mass production and used in military and civilian aviation, including from unprepared runways.
Externally, the Do 29 was very similar to the multipurpose Do 27, from which it successfully adopted about 70% of serial parts. However, unlike the last fuselage, the Do 29 aircraft received a completely new cockpit with glass panels, stronger structural elements behind the carrying planes and ejection seats for pilots. The bearing planes in this case were largely borrowed from Do 27, however, due to the insertion of an additional section 1,2 long in the center section, the wing span of the aircraft grew to the 13,2 meter. The tail of the aircraft as a whole was also borrowed from Do 27, and the rudder increased in size by about a third. The chassis was also strengthened and attached to the fuselage.
The power plant of the experimental aircraft included two piston aircraft engines manufactured by Lycoming, and for the first time a system for repeating nacelles relative to the vertical plane tested on the Do 29 aircraft. By that time, Dornier already had some experience in designing such systems. Here you can recall the elegant model Do 26. This aircraft engines could move relative to the vertical axis, along with elongated drive shafts. When developing the Do 29 aircraft, its creators decided to follow a different path: in the experimental machine, only the rear part of the power plant was modified so that it was easy to move the pushing propellers of larger diameter relative to the vertical axis by an angle of up to 90 degrees. For some reason, exactly piston aircraft engines were installed on the plane, although turbofan engines, due to a simpler cooling system and less weight, would be much more preferable.
Both piston engines of the experimental machine were interconnected by means of three transverse drive shafts, thanks to this, synchronization was achieved in the work of pushing propellers with opposite rotation. In the event that one of the engines failed for some reason, the second due to the permutation of the angle of the propeller blades was supposed to allow up to 70% of the total thrust of the aircraft power plant. Externally, the Do 29 was not the most beautiful aircraft, although it is certainly a matter of taste. That did not prevent him from receiving a number of positive functions, among which were relatively small sizes.
When creating this project, the designers of the aircraft proceeded from the considerations that their car with shortened takeoff and landing, as well as with a fixed wing, can be assembled in two ways, each of the methods provided for a small specific load on the bearing surfaces:
1. Use of propellers with a change in air flow, which was thrown off the screws with the help of flaps divided into separate elements;
2. The use of pushing propellers and control the direction of air flow from the screws by adjusting the position of the propellers, as well as moving the propellers relative to the vertical plane.
When flying at low speeds, the second option turned out to be preferable; this was shown by tests in a wind tunnel, the reason was a large developed vertical thrust. It was the second option that was chosen when building flight samples of an experimental Do 29 aircraft. After a sufficiently large number of preliminary tests and studies, Dornier finally began to build a flight model. At the same time in the German press there was information that the cruising speed of the aircraft will reach 290 km / h, and the minimum - 25 km / h. If these data were correct, then the realized value of the speed range (the ratio of maximum and minimum speed) equal to 12 meant that the aircraft designers managed to get very high technical specifications for that level of engineering and time.
21 December 1958, the flying prototype of the Do 29 aircraft with shortened takeoff and landing, made its first flight. Dornier test pilot of the Dornier company Heinrich Schäfer raised the car to the sky. The flight tests conducted showed that the statements in the German press were rather optimistic. Although the aircraft had good stability during the flight and was well-controlled in various flight modes, including critical modes, its cruising speed was not only the 290 km / h originally declared, but only about 230 km / h. The same happened with the minimum allowable flight speed, which turned out to be true, not originally announced by 25 km / h, but approximately 70 km / h. In addition, during the flight tests, some problems with the synchronization of the rotary system of drive shafts were identified. There were other problems. But despite a number of shortcomings identified during the tests, in general, a successful Do 29 could open up to Dornier a fairly wide field of activity for the company.
Although Do 29 was by no means the best aircraft in the world of his years, he coped well with the role of a test bench with fairly good flight data. Some of the results achieved during his tests indicate that if this program was continued, the German designers could achieve a certain increase in cruising flight speed compared to that demonstrated during the tests, and that with additional refinement of the control system it would have been possible to achieve better aircraft controllability at low flight speeds. However, this did not happen: as in the case of other projects of the German post-war industry, the program for creating an aircraft with a shortened takeoff and landing was stopped, this happened even before the designers could make any significant improvements to their aircraft.
In total, in Germany, two flight copies of the Do 29 aircraft were assembled, these machines were completely completed and flown in during the tests. Another aircraft of this type was partially assembled, but not completed, it was never registered. Today, everyone can see the Dornier Do 29 aircraft with their own eyes. One of the copies of this machine is stored in Friedrichshafen in the aviation museum of the company Dornier.
Flight technical characteristics of Dornier Do 29:
Overall dimensions: length - 9,5 m, height - 2,7 m, wing span - 13,2 m, wing area - 21,8 m2.
Empty weight - 1820 kg.
Normal take-off weight - 2490 kg.
Powerplant - 2 PD Lycoming GO-480-B1A6 with horsepower 2x270 hp
The maximum flight speed is 290 km / h.
Cruising flight speed - 244 km / h.
Practical range - 400 km.
Practical ceiling - 6500 m.
Crew - 1-2 person.
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