04 February 2011

Dr. Hans Multhopp's Raven and Its Legacy

Dr. Hans Multhopp and a model of his Ta 183 fighter
By 1942 both Messerschmitt and Heinkel had flown jet fighter prototypes but other great fighter aircraft manufacturer of Germany at the time, Focke-Wulf, was lagging behind in jet aircraft development with the technical director of the company, Kurt Tank, still working on preliminary ideas for a jet fighter aircraft. Tank's first designs resembled the Heinkel He 162 with a single, dorsal-mounted engine. As Tank refined the design further, the engine moved into the fuselage with a nose intake, then it got lateral intakes, twin fins and finally ended up as a single-engine twin-boom fighter that resembled the De Havilland Vampire and was named the "Flitzer" (Dasher). However, Tank's protege in the company, Hans Multhopp, had been working on something even more spectacular than the Flitzer. Multhopp joined Focke-Wulf in 1938, having been recruited by Tank himself from the University of Gottingen where he worked under the famed aerodynamicist Ludwig Prandtl. By 1940 Multhopp was second-in-charge of the company's aerodynamics department and by 1943 Tank had promoted him to head the company's advanced design bureau. It was here that Multhopp developed what was called Project V. Multhopp had christened his design "Huckebein" after a mischievous raven in a children's cartoon of the day. The Huckebein had sharply swept wings and a raked back T-tail that gave it an appearance that was nothing like any design in the works anywhere at the time. 

Kurt Tank's Flitzer design
Tank was dubious about the features of the Huckebein and had scale models of both the Flitzer and the Huckebein built and tested. Despite the tests not uncovering any flaws with the Huckebein, Tank continued work on his own Flitzer but by 1944 it was quite apparent that it couldn't deliver the performance the Luftwaffe desired, which was for a jet fighter aircraft that could outperform the Messerschmitt Me 262. Even though the Me 262 was quite capable in many respects, the German air ministry, the RLM, had overstated the progress of the Allies in jet fighter aircraft development. In addition, by 1944 it was apparent that the Boeing B-29 Superfortress could outperform the B-17 and B-24 bombers that were hitting the Reich regularly. The main drawback of the Me 262 was that in using two engines, it used up per aircraft twice the scarce materials than a single-engined aircraft. Because of this, the RLM and the Luftwaffe exercised even tighter control over fighter aircraft development that in hindsight, were excessively bureaucratic. 

In 1944 with Tank having to accept that the company would have to focus its development resources on the Huckebein, the RLM issued a specification for a high performance fighter powered by a single Heinkel HeS 011 jet engine. Messerschmitt submitted what was to become the P.1011 fighter. Focke Wulf submitted Multhopp's Huckebein and even seaplane builder Blohm und Voss submitted a fighter design. Through the winter of 1944-1945 RLM officials and Luftwaffe staff endlessly deliberated the merits of each design and even discussed revamping the specification- as Allied armies were approaching the Rhine in the West and the Soviet Red Army was continuing its relentless push on the Eastern Front. Junkers was then invited to submit their design as well. With no progress being made, the Luftwaffe High Command called an emergency meeting in February 1945 to resolve the matter and the Focke Wulf Huckebein was selected as the Ta 183 ("Ta" in reference to Kurt Tank) to be the interim design while the Messerschmitt design was regarded as the optimal design for further development to supplant the Ta 183 in service. Plans were drawn up sixteen test Ta 183 aircraft with a maiden flight planned for May or June 1945 with the first production fighters being delivered to the Luftwaffe in October 1945. 
Ta 183 Design III, this influenced the Saab J29 Tunnan

The Ta 183 was aerodynamically very advanced with a 40 degree, thin, swept wing that had low wing loading for high altitude performance and maneuverability. The sharply raked back vertical fin mounted a T-tail unit that was used only for trimming purposes with pitch and roll to be handled only by the wing surfaces. The cockpit was pressurized and aircraft was armed with hard-hitting 30mm cannon. An alternate variation of the Ta 183 was also envisioned with a less sharply swept wing, a conventional tail unit and longer fuselage- this was the Design III which Tank worked on while Multhopp refined the original Ta 183 which was designated Design II. 

The Ta 183 is a popular subject of "What-If" modeling
Work proceeded quickly after that February meeting, but the following month the Allies crossed the Rhine into Germany and work on the Ta 183 under Hans Multhopp and Kurt Tank ground to a halt when the British Army captured Bad Eilsen, the location of Focke-Wulf's design department. The fall of Nazi Germany left the Allies an impressive treasure trove of aeronautical progress. The British initially failed to realize the technological leap the Ta 183 represented when they sifted through the captured material at Bad Eilsen. The Soviets, however, were quick to realize the Ta 183's potential, having found a complete set of plans on microfilm when they captured the RLM headquarters in Berlin. While the plans were examined by Artyom Mikoyan and Mikhail Gurevich of the MiG design bureau, it would be fallacy to say that the MiG-15 is a copy of the Ta 183 as Mikoyan and Gurevich were talented designers in the their own right. Perhaps their examination of the Ta 183 plans confirmed their own intuitions on how best to proceed with the MiG-15. There is no doubt, though, that Sweden managed to get a hold of the Ta 183 plans and data and that it is believed to have influenced their own design work on the Saab J 29 Tunnan fighter. 

Following the end of the Second World War, Kurt Tank and Hans Multhopp parted ways, with Tank moving on to work on projects in Argentina and India (subject for future blog posts, stay tuned!). Multhopp and a team of his assistants went to work at Farnborough in the UK and developed plans for a transonic research aircraft powered by an Rolls-Royce Avon turbojet with 60-degree swept wings and a T-tail with the pilot sitting prone in the shock cone of the nose intake. However, Britain was economically spent after the war and Multhopp's design never got built. In 1949 he moved to the United States and went to work with the Glenn L. Martin Company where he worked on two designs that also had T-tails- the XB-51 tactical bomber and the P6M Seamaster jet flying boat. He would later become the chief scientist for Martin Aircraft and his career would culminate with Martin's pioneering work on lifting body spaceplane designs like the X-23/PRIME and the X-24 which provided much data for the NASA Space Shuttle program. 

While the Ta 183 was only one of many advanced designs being worked on in Germany during the Second World War, it is probably the most emblematic of Germany's influence on postwar aircraft design. Many designs that were considered ground breaking in the 1940s like the Boeing B-47 Stratojet and the North American F-86 Sabre, originally began as less-than-spectacular straight wing designs that were reworked to incorporate what was being learned from the analysis of captured German aeronautical research.

Source: Aircraft, January 2011, Volume 44, Number 1. "The Luftwaffe's Last Hope" by Bruce Hales-Dutton, p46-50.

1 comment:

  1. I work with Hans' other son, Volker....Here in Maryland.