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PUL-10 Brochure Usually airplanes consist of a fuselage, wings and a tail-section. Professor Reimar Horten envisioned an airplane consisting only of a wing, containing all systems, passengers, and cargo. Throughout the 1930's and 1940's several flying wings of his design were built and successfully tested under his supervision. But after World War II Germany was prohibited from developing aircraft. So in 1948, Dr. Horten emigrated to Argentina where he could continue his work. When we met him forty years later he became our friend and our teacher. Over the years he taught us the principles of flying wing construction as he continued to design flying wings, including the two seat PUL 10. On March 14, 1993 Reimar Horten passed away. We will always remember him with gratitude, for without him, this project could never have existed. He was decades ahead of his time. We also would like to thank all the people who have helped us to develop the PUL 10. The American Northrop company used the advantages of the flying wing for the construcction of the Northrop Grumman B-2 bomber. We may never understand civil aviation's failure to accept the flying wing with all its advantages; simplicity, economy, efficiency, and safety. In the 1940's these advantages were well known by scientists and engineers throughout the world. In Germany, Junkers, Messerschmidt, BMW, Heinkel and Focke-Wulf were submitting flying wing proposals to the Ministry of Aviation. In America, Northrop was breaking records with the YB-49. The prototype PUL 10, conceptualized by Prof. Horten, reveals the potential of the flying wing concept – though yet not developped enough to be mass-produced. Our experience with flying wings has convinced us that if the flying wing had gone through half a century of development, the conventional airplane would have been obsolete long ago. The two seater PUL 10 is not the only flying wing we can build. We have construction plans for a four seater flying wing, along with plans for several gliders, all designed by Prof. Horten. Th PUL 10 has proven itself far easier and cheaper to build and more efficient to operate than any competitor of comparable size. The flying wing which can carry more cargo with 30 to 60% less fuel will be a success in a future of possibly limited resources. The development of the flying wing is still in its infancy but it has the potential to change aviation. We would appreciate your ideas, critics, collaboration or investment in our flying-wing project.
Low fuel consumption Because the PUL 10 is reduced to a flying wing it does not suffer the drag of a fuselage and tail section. Therefore it consumes less fuel. Even though we use a fixed pitch propeller, the PUL 10 cruises at 97 knots while burning only 2.9 gallons per hour. This is 30 to 60% less fuel than a conventional airplane of approximately the same size and speed. The decreased wing loading of the PUL 10 reduces induced drag while the elimination of fuselage and tail reduces parasite drag.(See "Calculations for PUL 10" by the Stadler engineering office.) Cheaper fuel While most Continental and all Lycoming engines require AVGAS 100 LL, the PUL 10 is equipped with an engine that can use automobile fuel. Large usable volume The thicker and longer profile of the wing achieves more usable volume than a comparable plane with a fuselage. Longer range 640 nautical miles with 45 minutes reserve. (The 23.8 gallon fuel capacity still leaves room for more luggage than a comparable size conventional airplane can offer.) The fuel tanks of the prototype are placed within the 2.45 m (8 ft) wide center section. The space inside the wing parts has not yet been used. Safety Dr. Horten calculated a spanwise lift distribution that eliminates the danger of spinning (so long as the center of gravity is within prescribed limits.) Upon flight testing the Horten II on November 12, 1938, the celebrated test pilot Hanna Reitsch had this to say: "Through no possible movement of the stick could I get the H II to start spinning or to fall over one of its wings. When I pulled the stick back and to the right, the plane pitched slightly forward and started sinking without accelerating to more than 90 km/hr. This is of great help while flying in clouds with frozen instruments" Dr. Horten achieved these flying characteristics through airfoil design and wing twist that concentrate most of the lift in the center of the plane. He succeeded in keeping the air flow attached to the elevons even at minimum speeds. This air flow characteristic can be most impressively demonstrated by attaching pieces of yarn to the top of the wing and flying it in slow flight. At 40 knots the yarn shows air flow separation from the middle of the wing but it never separates out near the elevons. The nose lowers slightly as the plane accelerates without any compromise of control. Lower minimum speed Flying wings have light wingloading. Consequently they can fly very slowly. The PUL 10 can fly at 38 knots without sinking. Its touchdown speed is only 30 knots, which greatly reduces takeoff and landing distances and the risk of accidents, especially in a short field. Integrated parachute In case of emergency, a parachute can be fired out instantly. The parachute lowers the plane and its passengers. The installation of such a parachute is possible for all small planes today, unfortunately it is not standard yet. Hangaring and transport Since the flying wing does not have fuselage or tail-section, it needs less space in the hangar. Even in an occupied hangar there is space for the PUL 10. Because of its low wings it can be placed underneath the wings of a high wing plane. In addition, the PUL 10 can be disassembled into three parts within half an hour. It is easily transported on a 6,5 x 2,5 m (21,3 x 8,2 ft) trailer. Easier maintenance There is less to the airframe and the control system. There is more room for hands and tools wherever mechanical work must be done. Production costs The production costs for a flying wing are lower than for conventional planes because its shape is more compact and the steering mechanics are simpler (no rudder or elevator). When traveling by plane, the final destination is often far away from the airport itshelf. Time and money spent on taxies often spoils the advantages of flying. There have been many thinking about a way to combine a plane with a car. However all practical attempts have failed. It was not known how to build a plane without a fuselage that could fly safely and dismounting the fuselage and tail section was too complicated. With the flying wing concept the dream of many pilots comes true: Flying wings have brilliant flight characteristics and become compact vehicles on the road when the wings are dismounted. As all important parts such as engine, tank and landing gear are situated in the center-section, mounting and dismounting could be improved in a way that enables the pilot to do the necessary changes himshelf. Discussions with German authorities have shown all technical requirements for driving can be met.
In 1933, Reimar Horten built his first flying wing, a one man carrying glider in his parents' house. Encouraged by its success, he built the Horten II, the world's first motor glider. By now his flying wings were attracting so much attention that he was helped to continue his work. He built many prototypes, most with plans for mass production. By 1944 the Peschke company had placed an order for more than 20 Horten VII flying wings, and the Klemm company placed an order for 50 Horten IIIe. Such well known companies as Junkers, Heinkel, Messerschmidt, BMW and Focke-Wulf were submitting flying wing designs to the Ministry of Aviation as the war was ending and Germany had achieved a leading position in aeronautics. This is probably why airplane construction was prohibited in Germany after the war. Flying wing development in Germany ended. Many flying wings were destroyed, some were taken to the United States. (At the time of writing, four flying wings from the United States are being restored in Berlin.) The United States was very interested in what had German engineers had learned from flying wings. We suspect that this led to the decision to build the B-47 with swept back wings rather than the straight wing of its earliest designs. In 1948 Dr. Horten emigrated to Argentina where he was able to continue his work on flying wings. There he supervised the construction of a couple of flying wings, including the four engine AE 38 transport which could carry 10 tons more than 1100 nautical miles. Unfortunately, the general who supported flying wing development was replaced by someone who ordered the transporter to be grounded. At the university he was only allowed to teach the construction of conventional aircraft and his communication with aircraft builders in other countries was disrupted by the censorship and opening of his mail. In 1950 German researchers attempted to build flying wings, but without the experience and background of Dr. Horten, they were so unsuccessful that many believed that the flying wing could not be built. Throughout his life Dr. Horten was plagued with what he called the „studied narrow mindedness" of his colleagues. For example, in 1943 a famous aerodynamics scientist declared, "Sweptback wing designs run the risk of falling over one wing with loss of control over the plane" even though Horten's airplanes had no such problem. More information is contained in the book: "Nurflügel, die Geschichte der Horten-Nurflügel 1933-1960" by Reimar Horten and Peter F. Sellinger, Weishaupt-Verlag Graz ISBN 3-900310-09-2. Additionally you can find information and pictures in the Internet: http://www.nurflugel.com. In 1987, we met Prof. Dr. Reimar Horten in Argentina. In the following years we built a number of radio controlled models according to his construction plans. The models flew so successfully that we built a single seat prototype. In the winter of 1989-1990, Siegfried Panek, one of the main builders of the PUL 10, worked with Dr. Horten on construction detail plans. In January 1990 we began construction of the PUL 9 (Panek Ultra-Light 9 meter wing span) in a little village near Frankfurt. In April we took it to Italy where Nike Aeronautica helped us to finish building it, and it made its first flight on June 22 1990. The PUL 9 was thoroughly tested under many different flight conditions. We were highly impressed by its easy handling and stability in the air. In 1991 we decided to build a two seater. In the winter of 1991-1992 , Siegfried Panek and Reimar Horten built a wooden model which was called the PUL 10. In February 1992, we started to build the molds out of 3-dimensional fiberglass. We used this material for the body of this plane too. Even though the first PUL 10 turned out to be much heavier than we expected, it demonstrated very good flying characteristics in it's September 1992 test flight. Satisfied with its aerodynamics, we began construction of the second PUL 10. This second plane took more time to build because we reworked some of the molds for later mass production. We began testing it in Italy in summer 1994 and in spring 1995 we registered it in France and continued testing at Sarrebourg airfield. In 1995 we replaced the 2-stroke Rotax 582 with a 4-stroke Rotax 912. In June 1995, during a flight test over France, stalls were performed with a C.G. too far aft. In one of these stalls, the airplane went into a spin which forced the pilot to use the built-in parachute. The landing damaged the airframe beyond repair. But by now we had gained enough knowledge to begin construction of the third PUL 10 in fall 1995. This PUL 10 differs from its predecessors only in equipment and engine mounts. The shape of the plane was not changed. We finished it in fall 1996 and received an experimental registration in Germany. You can find current pictures of the engine mount in the Internet: http://www.cso.net/kurri/flug/pul10.htm The initial take-off with german registration took place on the Breitscheid airfield on May 14th 1997. Flight tests have been without major problems ever since. One minor problem was the retractable gear which didn`t always extend properly. Once it was even necessary to land with the gear retracted. Apart from slight scratches underneath and a leaking radiator there weren`t any damages worth mentioning. Because of permanent flaws in the exaust manifold and problems with the engine cooling, we were forced to fly mainly in the local area. However, the PUL 10 was able to be flown about 50 hours. Because of persistent engine problems we decided to change the engine. In the winter 97/98 a 90 hp BMW motorcycle engine was installed. The interest in the new plane is constantly growing. Almost daily we receive letters and phone calls. Some interested people said they had worked on flying wing development under Reimar Horten. They were enthusiastic about the flying wings characteristics and wondered why the development had not been continued over the past 45 years. The rumour about the rebirth of the flying wing has spread like wildfire. Accounts of it have been published on almost every continent. Also the german media show more and more interest in this extraordinary project. Since its initial flight in May 97, 6 German TV-companies have reported on the PUL 10. A summary of the most important European press-publications and a video-tape of all TV-reports can be ordered (price of this "info-package" on request). Many inquiries came from America and Australia. In these countries private aviation is of great importance. In Australia the enormous distances between cities and small settlements would make life difficult if it were not for small private aircraft. Some flying wing enthusiasts have visited us to see the PUL 10 in action. Some clubs such as TWITT ("The Wing Is The Thing") have contacted us too. Many of the people we talked to were dissatisfied with the lack of progress in conventional airplane design. Some are willing to wait until the flying wing becomes available before buying a plane. One prestigious organisation, the Oskar-Ursinus-Association, awarded the constructors of the PUL 10 the first prize for the most progressive design in 1994 and 1997.
With the right investment and demand, the sky is the limit. In 1992 Dr. Horten designed a four seater flying wing with a 12 meter wing span. Normal registration of such an aircraft for mass production would be too expensive for all but the largest companies. However, for the American market, a four seater kit is possible. Dr. Horten left us with the knowledge to build even bigger flying wings. He thought of a giant flying wing capable of carrying approximately 1000 passengers, and having a weight of 1000 tons, that would fly 30 meters / 100 ft over the water in ground effect at a speed of 600 km/h / 330 knots, connecting the continents at a fraction of the previous cost. Take off and landing would take place on the water. This would be a definite advantage over today's airliners with their pressurized cabins and air pollution. Due to latest reports US plane manufacturer McDonell Douglas and NASA have taken up Prof. Hortens idea. A flying wing for 800 passengers is planned to go on its maiden flight in 2010. The designers expect fuel consumption to be reduced by one third. The past seems to catch up - why hesitate any longer? Horten PUL 10 Dr. Barney Vincelette,
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