Postby zodiaque » June 8th, 2005, 7:53 pm
Felix Wankel originated the idea of rotary engine as early as the 20's but development started as late as 1954 when he persuaded NSU, then a motorcycle maker, to fund the project.
In theory, the rotary engine has a lot of fascinating advantages. Firstly, the rotors spin in one direction, unlike piston which changes direction reciprocately, thus being smoother and waste less energy. Secondly, it uses less components - a 2-rotor Wankel engine equivalent to conventional 6 cylinders, then no valves, no rocker arms, no camshaft, no crankshaft and connecting rods, it could be smaller, lighter and simpler than piston engine. Thirdly, lack of valve-gear mechanism and crankshaft leads to less vibration as well as less noise.
NSU's rotary engine
Dr. Wankel experimented his first rotary engine in NSU, which eliminated the imperfect eccentric movement of rotor by a revolving housing which was held by another housing. It was perfectly smooth, but too complicated to implement in economical way. Therefore at last a more compromised design, with eccentric rotor and a single fixed housing (that is the one Mazda still uses in today) was adopted.
The first production rotary car was the 1963 NSU Spyder, a small car like Fiat 850 Spyder. It has a single rotor with capacity of 498cc. This was just a low volume experimental project.
The real ambitious application of rotary engine appeared in 1967 when NSU launched its famous RO 80 mid-size sedan, which won European Car Of The Year in that year. Two rotors output 115hp smoothly, but quickly was found to be indurable. Tip sealing wear quickly, increasing fuel consumption, dropping power and even leak oil. This cost NSU a lot for servicing, and established bad reputation for Wankel engine. As a result, NSU was destroyed by this engine and eventually was absorbed by the Volkswagen group. It never produced rotary engine since then.
However, Wankel engine attracted international attention. To raise the development budget, NSU sold the license for United States to an aircraft engine maker called Curtiss-Wright, which then sub-licensed to General Motors, Ford and other car makers.
