Loading please wait....

If you are a registered, please log in. If not, please click here to register.

The Continental Motors Group has declared its commitment to the diesel engine as a forward-looking drive concept for aircraft- as evidenced by the acquisition and inclusion of Centurion diesel aircraft engines in its product portfolio. In the summer of 2013 a new era for aircraft engines was initiated and looking back in the history of propulsion systems we see famous engineers and their inventions. Now- on the hundredth anniversary of his death- Continental Motors is commemorating the German inventor and engineer- Rudolf Diesel- whose intellectual achievements paved the way for a new drive concept – even though he certainly never thought his invention would one day be used in small aircraft.

Would Rudolf Diesel have imagined…

...... that someone would one day have the idea of using his “highly effective internal combustion engine” to propel airplanes? Surely not. After all- his first diesel engine that was ready for production weighed a cool 4.4 metric tons. Use in automobile construction- let alone the weight-sensitive aviation industry- was unthinkable at the time.

Now- in the year 2013- we are remembering the 100th anniversary of the death of Rudolf Diesel- engineer and inventor. A fitting occasion to take a look at his life’s work and the principle named after him- on which the Centurion engines of the Continental Motors Group are based.

Rudolf Christian Diesel was born in Paris to German emigrants in 1858. His talent was discovered early. At the age of twelve- he received a prize from the “Société Pour L’Instruction Elémentaire” for his outstanding achievements at school.

After finishing school in Augsburg- Germany in 1872- Diesel decided to become a “mechanic” (engineer really). Following trade school and education at the industrial school- he started his studies at the Technical University in Munich- completing them in 1880.

He then worked on the development of ice and refrigeration machines at the firm Linde in Paris. It was there that he received his first patent on a process for the production of clear ice in bottles. On February 27- 1892- Rudolf Diesel applied for a patent on a “new rational heat engine” from the Imperial Patent Office in Berlin. He thereby laid the foundation for his future developments.

In his initial experiments- Diesel used petroleum. But as this fuel was not suitable for utilization- he then had to use gasoline in order to obtain ignition. Using a converted carburetor- the fuel was sprayed and blown into the combustion chamber alongside air under high pressure. The pressure required was generated via a compressor- a so-called blowing machine. However- this proved to be very complicated and prone to faults.

One of Diesel’s greatest problems at first was that some of the gasoline burned in the pipe because the compressed air became too hot. For this reason- multi-stage compression and cooling were carried out. Nevertheless- the hot air had to be capable of igniting the (very rich) mixture blown into the combustion chamber.

In 1893- Rudolf Diesel began to develop the diesel engine in the MAN AG engineering plant in Augsburg. The first engines presented Diesel and his team with major problems. It was not rare for them to explode and endanger the lives of the developers. The problem lay in the injection of the fuel. Diesel did not manage to solve this until after a meeting with Robert Bosch in 1894. The reduction of the compression pressure from 250 bars to 35 bars proved to be the breakthrough- yielding the first usable results from 1896.

The six months that had been estimated for the development of the engine to a productionready state ultimately became four years- with the first operational diesel engine being completed in 1897. The thermal efficiency of the first diesel engine to be operated in 1897 was 26.6 percent. Thermal efficiency refers to the effective use of the fuel energy. For comparison purposes- the steam engine achieved around 10 percent- modern car engines attain values of up to 45 percent- while large engines can reach over 50 percent.

As part of a trial run for inspection purposes- Professor Schröter from the Technical University of Munich confirmed the engine’s workability to Diesel. It provided approximately 20 hp in power and consumed substantially less fuel than other engines of the period.

The Dieselmotorenfabrik Augsburg factory was founded on January 1- 1898. The Diesel Engine Company in London was founded in the fall of 1900. At first- only stationary diesel engines were built. It was not until 1903 that the first motor ships were equipped with diesel engines. The powering of submarines was a particular focus.

Alongside numerous tiresome patent law suits- Diesel’s life was also shaped by his poor health. He was last seen alive on a ship in the English Channel on September 29- 1913. The exact circumstances of his death are still unknown. In 1912- while he was still living- the number of diesel engines in use or under construction throughout the world reached around 1-720-000. Over 100 factories were working on the construction of diesel engines. “Dieseln” became a German verb.

The use of diesel engines in cars occurred for the first time in the years 1923/24. Due to their enormous weight compared to gasoline engines- which had already been used to power cars for a decade- the deployment of diesel engines had not been possible. One reason for their weight was the higher pressure occurring in diesel engines- which could only be controlled through robust construction. But the main reason lay in the supply of the fuel. Diesel initially used compressed air for this purpose- which was only possible with elaborate supplementary units. When using an injection pump- the supplementary units are not required and the conditions for use in cars are fulfilled.

Diesel for aviation

The Packard Motor Car Company introduced the first diesel airplane in 1928. Hugo Junkers presented the first diesel aircraft motor ready for production a year later. Its economical nature and its operational safety make the diesel engine appear to be a promising drive unit for airplanes. But despite the developments that diesel technology has undergone over the years- it was for a long time unsuitable for airplanes in general aviation- due to its unfavorable power/weight ratio.

This disadvantage could only be eliminated by the introduction of lighter materials- modern turbochargers and common rail technology. It is now possible to take advantage of the economical nature of diesel technology in general aviation. Our Centurion engines are developed based on mass-produced components from the automotive industry that have proven themselves many times over. Due to the physical similarity of diesel and kerosene- they can be operated with both fuels in any mixture ratio.

However- before the diesel could enter the air- important development work was necessary to obtain the required aviation certificates.

One example in brief :

- electronic engine management system (FADEC)- gear box with clutch and torsional damper- adaptation of the fuel system for kerosene (jet fuel) as well as various developments to the engine’s periphery and the engine components.

Following years of development work- Centurion engines are now approved for the most common training airplanes- e.g. Cessna 172 and 206- Piper PA28- Robin DR400 and the DA40 TDI and DA42 Twin Star. The low costs for fuels and service make Centurion engines of interest for flight schools- charter companies and associations as well as all pilots who wish to profit from these. They are also used in regions of the world where the availability of leaded aviation fuel is not guaranteed. Finally- Centurion engines can also be operated using kerosene (jet fuel)- which is a medium distillate of crude oil- like diesel- and is also the standard fuel in the aviation industry.

- The proportion of diesel used for cars in Western Europe is now approximately 50 percent- while the figure for trucks is 95 percent.

- Around the world- over 2-600 airplanes in the general aviation industry are already flying with Centurion engines.

Could Rudolf Diesel have imagined it?

Related Articles

linkedin Print

Other Articles