Walter Kaaden (1 September 1919 – 3 March 1996) was a German engineer who improved the performance of

two-stroke engine A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...

s by understanding the role of

resonance Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...

waves in the

exhaust system An exhaust system is used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall system ...

. Working for the

MZ Motorrad- und Zweiradwerk Motorenwerke Zschopau GmbH (formerly MZ Motorrad- und Zweiradwerk GmbH) is a German motorcycle manufacturer located in Zschopau, Saxony. The acronym MZ since 1956 stands for ''Motorenwerke Zschopau'' GmbH (German for Zschopau engine factory). F ...

part of the

Industrieverband Fahrzeugbau ''Industrieverband Fahrzeugbau'' ("Industrial Association for Vehicle Construction"), usually abbreviated as IFA, was a conglomerate and a union of companies for vehicle construction in the former East Germany. IFA produced bicycles, motorcycles ...

(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 200BHP/litre with his

1961 Events January * January 3 ** United States President Dwight D. Eisenhower announces that the United States has severed diplomatic and consular relations with Cuba ( Cuba–United States relations are restored in 2015). ** Aero Flight 311 ...

125cc racer.''Halcyon days: MZ a potted history'' Alan Turner, Motorcycle Sport and Leisure, No. 577 October 2008, pp114-118 His motorcycle engines were ridden to 13

Grand Prix Grand Prix ( , meaning ''Grand Prize''; plural Grands Prix), is a name sometimes used for competitions or sport events, alluding to the winner receiving a prize, trophy or honour Grand Prix or grand prix may refer to: Arts and entertainment ...

victories and a further 105 podium finishes between

1955 Events January * January 3 – José Ramón Guizado becomes president of Panama. * January 17 – , the first nuclear-powered submarine, puts to sea for the first time, from Groton, Connecticut. * January 18– 20 – Battle of Yijian ...

and

1976 Events January * January 3 – The International Covenant on Economic, Social and Cultural Rights enters into force. * January 5 – The Pol Pot regime proclaims a new constitution for Democratic Kampuchea. * January 11 – The 1976 Phila ...

.''MZ - the racers'' by Jan Leek, 650 Publications, 1991, Walter Kaaden was born in

Pobershau Pobershau is a former municipality in the district Erzgebirgskreis, in Saxony, Germany. With effect from 1 January 2012, it has been incorporated into the town of Marienberg.

, Saxony, Germany. His father worked as chauffeur to the sales manager at the

DKW DKW (''Dampf-Kraft-Wagen'', en, "steam-powered car", also ''Deutsche Kinder-Wagen'' en, "German children's car". ''Das-Kleine-Wunder'', en, "the little wonder" or ''Des-Knaben-Wunsch'', en, "the boy's wish"- from when the company built to ...

factory. At eight years old he attended the opening of the

Nürburgring The is a 150,000 person capacity motorsports complex located in the town of Nürburg, Rhineland-Palatinate, Germany. It features a Formula One, Grand Prix race track built in 1984, and a long "North loop" track, built in the 1920s, around t ...

racing circuit, a formative event to which he later attributed his enthusiasm for engineering. Kaaden studied at the Technical Academy in

Chemnitz Chemnitz (; from 1953 to 1990: Karl-Marx-Stadt , ) is the third-largest city in the German state of Saxony after Leipzig and Dresden. It is the 28th largest city of Germany as well as the fourth largest city in the area of former East Germany a ...

. In 1940 he joined the

Henschel Henschel & Son (german: Henschel und Sohn) was a German company, located in Kassel, best known during the 20th century as a maker of transportation equipment, including locomotives, trucks, buses and trolleybuses, and armoured fighting vehicle ...

aircraft factory at Berlin-Schönefeld working under Herbert A. Wagner, the designer of the

Hs 293 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, ultimately damaging or sink ...

radio-guided rocket-propelled missile. Despite many reports to the contrary, Kaaden did not work on the

V-1 flying bomb The V-1 flying bomb (german: Vergeltungswaffe 1 "Vengeance Weapon 1") was an early cruise missile. Its official Ministry of Aviation (Nazi Germany), Reich Aviation Ministry () designation was Fi 103. It was also known to the Allies as the buz ...

(the Vergeltungswaffe 1, Fieseler Fi 103) nor under

Wernher von Braun Wernher Magnus Maximilian Freiherr von Braun ( , ; 23 March 191216 June 1977) was a German and American aerospace engineer and space architect. He was a member of the Nazi Party and Allgemeine SS, as well as the leading figure in the develop ...

on the

V-2 The V-2 (german: Vergeltungswaffe 2, lit=Retaliation Weapon 2), with the technical name ''Aggregat 4'' (A-4), was the world’s first long-range guided ballistic missile. The missile, powered by a liquid-propellant rocket engine, was develope ...

German rocket program during the Second World War. From 4 October 1943 he worked at the

Peenemünde Army Research Center The Peenemünde Army Research Center (german: Heeresversuchsanstalt Peenemünde, HVP) was founded in 1937 as one of five military proving grounds under the German Army Weapons Office (''Heereswaffenamt''). Several German guided missiles and ...

on the Hs 293 project as a 'flight engineer'. But the

bombing of Peenemünde in World War II The bombing of Peenemünde in World War II was carried out on several occasions as part of the overall Operation Crossbow to disrupt German secret weapon development. The first raid on Peenemünde, on the Baltic coast of Germany, was Operation H ...

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 The Harz () is a highland area in northern Germany. It has the highest elevations for that region, and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The name ''Harz'' derives from the Middle High German ...

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 to start a timber business specialising in roof trusses that were in great demand to renovate bomb-damaged buildings. Walter Kaaden built his first racing motorcycle, based on the DKW RT125, which he raced himself in local events in his company's workshop. In 1953, the IFA asked Kaaden to take over the management of the racing department from Kurt Kampf after the IFA 125cc racers had been outclassed by Bernhard Petruschke riding the private ZPH (Zimmermann-Petruschke-Henkel) machine whenever they had met the previous year. The independent engineer Daniel Zimmermann (born 1902) also based his ZPH engine on the pre-war DKW RT-125. Zimmermann heavily modified the engine by adding a disc valve that allowed asymmetric port timing with a longer duration inlet phase. Zimmermann also used a new crankshaft providing 'square' bore and stroke dimensions (54mm x 54mm) and used stuffing rings to boost the primary compression ratio. However, the East German government didn't like the competition between the two East Germans and persuaded Zimmermann to reveal his engine's secrets to Kaaden. The result was the 1953 IFA racer that featured a rotary disc valve - as per Zimmermann. This two stroke 125cc racing engine was producing 13 bhp, more than 100 bhp/litre. This engine was further developed to produce 25 bhp at 10,800rev/min.''Motorcycles - a technical history'' by CF Caunter, Her Majesty's Stationery Office, London, 1982, In 1955, Kaaden turned his attention to the

expansion chamber On a two-stroke engine, an expansion chamber or tuned pipe is a tuned exhaust system used to enhance its power output by improving its volumetric efficiency. History Expansion chambers were invented and successfully manufactured by Limbach, a ...

s invented by Erich Wolf (the DKW designer) that had first appeared on DKW's 1951 racers. Kurt Kampf had copied and fitted replicas of Wolf's design to the 1952 IFA racers."''IFA/MZ Renngeschichte 1949-1961''" by Manfred Woll, Heel Verlag GmbH, 2001, Working with extremely limited resources, in 1955, Kaaden developed the expansion chamber idea using an

oscilloscope An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

to examine the resonance in the exhaust system. From this he devised profiles to maximise the engine's efficiency.

References

Further reading