Nikolaus August Otto, born in 1832 in Holzhausen auf der Haide, was a self-taught engineer with a passion for engines. He started his career as a traveling salesman for a grocery company.

Despite lacking formal education, Otto's curiosity drove him to experiment tirelessly as he experimented with building his own engines in his spare time. He balanced his inventive pursuits with family life, married to Anna Gossi and father to seven children.

His future business partner, Eugen Langen, born in 1833 in Cologne, came from a more privileged background. The son of a sugar manufacturer, Langen studied at the Polytechnic Institute in Karlsruhe, gaining both technical knowledge and business acumen.

His involvement in the family's sugar business gave him practical experience in industry and commerce. In the partnership, he was the business-savvy industrialist who knew how to turn ideas into money.

The pair met in 1864 and formed a partnership that would change the course of engine history. They wanted to create an engine that was not only more fuel-efficient but also capable of delivering more power—something that could really drive industry forward.

Otto had been experimenting with four-stroke engines since 1861, but success eluded him. In 1864, fate intervened when Langen, impressed by Otto's work, decided to partner with him.

Their eureka moment came from an unlikely source - the atmospheric steam engines of the past. They wondered: could this principle be applied to a gas engine?

Otto and Langen's atmospheric gas engine, patented in 1866,
operated on a ingenious principle, like this:

1. The engine had a vertical cylinder, open at the top.

 2. A piston inside the cylinder was connected to a rack (a toothed bar).

 3. The rack engaged with a flywheel through a clutch mechanism.

 4. At the bottom of the cylinder, a mixture of gas and air was ignited.

 5. The explosion pushed the piston up quickly, creating a partial vacuum below it.

 6. As the piston reached the top, the clutch engaged.

 7. As the hot gases cooled and contracted, atmospheric pressure then pushed the piston back down.

 8. The downward stroke, assisted by gravity and the flywheel's momentum,
converted the vertical motion into useful rotational power, genius!

Their engine achieved an efficiency of about 11% - more than double that of Lenoir's engine.

This remarkable improvement was due to their innovative use of atmospheric pressure for the power stroke and the separation of the power and exhaust strokes, significantly improving fuel economy.

Despite its innovations, the engine had its drawbacks. It was extraordinarily tall, limiting its use to stationary applications. The motion it produced was uneven and jerky, not ideal for many applications. 

And then there was the noise - so violent that it earned the engine the nickname "the hammer of the gods."

Despite these drawbacks, the Otto and Langen engine was a significant improvement over previous designs:
 1. Their engine won a gold medal at the 1867 Paris World Exhibition, which is like winning an Oscar for best engine design

2. It was about three times more efficient than the Lenoir engine.

 3. Its commercial success allowed Otto to continue his research, leading to the development of the four-stroke engine in 1876 - a design that would define internal combustion engines for generations to come.

 4. The company they founded, N.A. Otto & Cie, later became Deutz AG, which still produces engines today.

 5. Their work laid the foundation for future internal combustion engine development.

 ▪ Sometimes, looking backward can inspire moving forward. Otto and Langen's use of atmospheric principles from old steam engines led to a breakthrough in gas engines.

 ▪ Efficiency improvements can be as revolutionary as entirely new inventions. Their engine's increased efficiency was its key selling point.

 Entrepreneurs:

 ▪ Partnerships that combine technical innovation with business acumen can be powerful. Otto's engineering skills and Langen's business background were crucial to their success.

▪ Success in one product (the atmospheric engine) can fund development of future innovations (Otto's four-stroke engine). Reinvesting in R&D is crucial for long-term success.

 ▪ Recognize the potential in imperfect but promising technologies. Despite its drawbacks, their engine's efficiency made it commercially viable.

 Educators:

 ▪ Use Otto and Langen's story to illustrate how cross-disciplinary knowledge can lead to innovations. Their combination of mechanical engineering and thermodynamics principles was key.

 ▪ Highlight the iterative nature of technological progress. Their engine was a stepping stone to Otto's four-stroke design.

While the atmospheric engine itself is no longer used, its legacy lives on. The four-stroke principle Otto later developed still dominates internal combustion engine design. Modern engines continue to focus on improving efficiency and reducing emissions, building on the foundation laid by Otto and Langen. The company they founded, now Deutz AG, continues to produce engines, a living testament to their lasting impact.

As we face new challenges in energy and transportation, the story of Otto and Langen reminds us of the power of innovation, collaboration, and perseverance. Their "hammer of the gods" may have fallen silent, but its echo continues to shape our world.

As we wrap up this pre-automotive engines series, on the next article, we shall talk about the unsung heroes of those times, those whose works behind the scenes would not have let these inventions see the light of day, had they not been around. Stay tuned!