Walter Kaaden (1 September 1919 – 3 March 1996)
Kaaden was a German engineer who improved the performance of two-stroke engines by understanding the role of resonance waves in the exhaust system. Working for the MZ Motorrad und Zweiradwerk part of the Industrieverband Fahrzeugbau (IFA), he laid the foundations of the modern two-stroke engine. His understanding of gas flow and resonance enabled him to make the first engine to achieve 200 BHP/litre with his 1961 125cc racer.[1] His motorcycle engines were ridden to 13 Grand Prix victories and a further 105 podium finishes between 1955 and 1976.
Walter Kaaden was born in Pobershau, Saxony, Germany. His father worked as chauffeur to the sales manager at the DKW factory. At eight years old he attended the opening of the Nürburgring racing circuit, a formative event to which he later attributed his enthusiasm for engineering.
Kaaden studied at the Technical Academy in Chemnitz and started out modestly as a locksmith and amateur motorcyclist with a passion for motorcycling. In 1940 he joined the Henschel aircraft factory at Berlin-Schönefeld working under Herbert A. Wagner, the designer of the Henschel Hs 293 radio-guided rocket-propelled missile.
Despite many reports to the contrary, Kaaden did not work on the V-1 flying bomb (the Vergeltungswaffe 1, Fieseler Fi 103) nor under Wernher von Braun on the V-2 German rocket program during the Second World War. From 4 October 1943 he worked at the Peenemünde Army Research Centre on the Hs 293 project as a 'flight engineer'.
The Henschel Hs 293 was a World War II German radio-guided glide bomb. It is the first operational anti-shipping missile, first used unsuccessfully on 25 August 1943 and then with increasing success over the next year, damaging or sinking at least 25 ships. Allied efforts to jam the radio control link were increasingly successful despite German efforts to counter them. The weapon remained in use through 1944 when it was also used as an air-to-ground weapon to attack bridges to prevent the Allied breakout after D-Day, but proved almost useless in this role.
But the bombing of Peenemünde in World War II on 17/18 August 1943 destroyed the facilities there. The Germans then moved missile production and testing into the secure, deep tunnel network built beneath the Harz mountains at the Mittelwerk factory, Dora-Mittelbau Concentration Camp. This is where Kaaden was transferred along with the Hs 293 project.
Kaaden was working near Dora-Mittelbau when he was captured and interned by the Americans at the end of the war. He eventually returned to Zschopau and started a timber business specialising in roof trusses that were in great demand to renovate bomb-damaged buildings. In his company's workshop, Walter Kaaden built his first racing motorcycle, based on the DKW RT125 but including some of his ideas, which he rode, successfully, in local racing events.
At the same time, the independent East German engineer Daniel Zimmermann (born 1902), heavily modified a pre-war DKW RT-125 to create his radical ZPH engine. Zimmermann added a rotary disc valve that allowed asymmetric port timing with a longer duration inlet phase. Zimmermann built a new crankshaft providing 'square' bore and stroke dimensions (54mm x 54mm) and used stuffing rings to boost the primary compression ratio. Using the power of the ZPH (Zimmermann-Petruschke-Henkel) engine to contest the 1952 GDR 125cc Championship, Zimmermann's team riders, veteran Bernhard Petruschke and novice Diethart Henkel, frequently beat the riders of the government-backed IFA factory team then being managed by Kurt Kämpf.
The East German government didn't like to see its sponsored IFA team riders beaten by privateer team riders and at the end of 1952, began 'leaning' heavily on Zimmermann to reveal his engine's secrets to IFA.
By February 1953, Zimmermann was finally persuaded and by March 1953, Kurt Kämpf had been moved sideways within IFA to make way for his successor, Walter Kaaden. The results of Kaaden's arrival as IFA's racing manager and a ZPH engine to copy, was the 1953 IFA factory racer featuring a rotary disc valve and many other ZPH features.
This two stroke 125cc racing engine was producing 13 bhp, more than 100 bhp/litre in it's infancy and was further developed to produce 25 bhp at 10,800rev/min. This was the same engine, the 124 c.c. single on which which Ernst Degner won the East and West German and Italian grands prix. It gave 25 b.h.p. at 10,800 r.p.m at that time.
In 1955, Kaaden turned his attention to the expansion chambers invented by Erich Wolf (the DKW designer) that had first appeared on DKW's 1951 racers. Kurt Kämpf had copied and fitted replicas of Wolf's design to the 1952 IFA racers. Despite the rest of the world believing that the days of the ‘two-stroke’ in racing were over, Kaaden refused to give up. He knew of the 'Kadenacy effect' developed in the early 1920s and 30s,
Working in the USA in the twenties and thirties in the rapidly expanding (and commercially profitable) diesel engine industry, the Hungarian-born development engineer and designer Michel Kadenacy discovered, and attempted to exploit, a peculiar phenomenon to do with the two-stroke cycle. He was not the first to gain at least an intuitive perception of its existence, because there is evidence that Alfred Scott understood it to some extent. But Scott did not investigate and formalise the phenomenon, whereas Kadenacy did, with the result that it has become known as the 'Kadenacy effect'.
Working in the USA in the twenties and thirties in the rapidly expanding (and commercially profitable) diesel engine industry, the Hungarian-born development engineer and designer Michel Kadenacy discovered, and attempted to exploit, a peculiar phenomenon to do with the two-stroke cycle. He was not the first to gain at least an intuitive perception of its existence, because there is evidence that Alfred Scott understood it to some extent. But Scott did not investigate and formalise the phenomenon, whereas Kadenacy did, with the result that it has become known as the 'Kadenacy effect'.
Using this along with further knowledge he had gained at Peenemünde, where the V1 Flying bomb pulse jet engine was created, he finally put the holy trinity together: expansion chamber, disc valve and boost port. The resulting MZ 125 was the first real threat to the then-dominating four-strokes. Picture: From Wikipedia, the free encyclopaedia. A Pulsejet (or pulse jet) is a type of jet engine in which combustion occurs in pulses.
Working with extremely limited resources, in 1955, Kaaden with the assistance of new employee, later in the project further developed the expansion chamber idea using an oscilloscope to now examine the resonance in the exhaust system. From this he devised profiles to maximise the engine's efficiency.
In 1956, Kaaden Identified a possible addition to help his team with its development. He signed him into his team, this was the 24-year-old East German rider Ernst Degner (a mechanic by trade and a very capable person), the gifted and intuitive rider seemed to know just what to do to further develop the then current engines, to make Kaaden’s two-strokes sing.
Suddenly the rest of the world sat up and took notice of the odd little East German operation and their primitive-looking two-strokes. His motorcycle engines were ridden to 13 Grand Prix victories and a further 105 podium finishing between 1955 to 1976.
In the beginning the MZ motorcycle business had begun as simply as possible – starting with the resumption of producing of the DKW RT 125 in 1946. When Liebe's spotted Kaaden's riders in the crowd in 1952, the factory had already been producing the modest IFA RT 125 for a year (Picture left), but the company's management's ambitions were much higher. They remembered what the talented engineer had been doing during the war and offered him a job. History remains silent as to what arguments convinced Kaaden to return to engineering at the Zschopau plant. He immediately became head of the racing motorcycle department, and it was here that his genius was revealed. While working on the development of two-stroke engines, designed with a rotating valve in the crankcase, he investigated wave effects in exhaust systems. Kaaden's so-called resonance exhaust significantly improved the performance of the engines. The results of his work were quickly recognized worldwide. Despite their modest budgets, factory teams fielded by MZ began to achieve significant success in World Championship competitions. Already in 1958 and 1959, East German motorcycles were winning runner-up positions in the 250cc racing class. The entire sports world marvelled at these achievements, but the Zschopau-based sports department jealously guarded its secrets.
A situation arose when an employee of MZ, Ernst Degner who was lucky enough to have escaped from behind the 'iron-curtain' of Eastern-Europe, took with him from MZ the formula for modern racing two-stroke design, information which he passed on to Suzuki and on which all future Japanese two-stroke engines were based. The Kaaden engine was now released, and a veritable war between two and four-stroke engines erupted among Japanese manufacturers. This war ended with the long-term dominance of Walter Kaaden's brainchild, and all manner of supercharged, complex multi-cylinder four-strokes faded into oblivion for decades. Picture: After leaving the Ministry of Health, Kaaden was a valued FIM activist.
Walter Kaaden, on the other hand, remained loyal to the MZ brand until the end, working in the sports department until its closure in 1975, and then in the off-road motorcycle department until the factory's final closure as it was unable to cope with the socio-political changes following the reunification of the two German states. He died in 1996, a distinguished FIM official.
Walter Kaaden started out modestly as a locksmith and amateur motorcyclist with a passion for motorcycling. It was thanks to him that not only were the excellent MZ machines created, but Japan dominated the racing world for years. (Lech Potynski)
My thanks to Lech Potynski and other for the information I have gleaned from the internet.
Return to 50cc Racing Hardware
