Ninety-seven years ago this week, on the afternoon of 30 September 1929, a German car heir strapped himself into a pod under a glider wing, alongside sixteen gunpowder rockets, lit them and shot into the sky over Frankfurt. Fritz von Opel stayed up for about 75 seconds. It was the first public flight of a purpose-built rocket aircraft.

The Opel RAK.1 was part of the world's first large-scale rocket programme, dreamed up by a car company for publicity and pushed by men who wanted to reach space. It ended with a broken landing skid, a very lucky pilot and headlines around the world.

Rocket Cars First

The idea came from Max Valier, a rocketry enthusiast born in Bozen, South Tyrol, and a co-founder of the German Spaceflight Society. He persuaded Fritz von Opel, grandson of the Opel company founder, that a rocket car would sell both rockets and cars. The rockets came from Friedrich Wilhelm Sander, a pyrotechnics maker in Bremerhaven who built black-powder rockets for harpoons and signals.

The results were spectacular. On 23 May 1928, von Opel drove the RAK 2, powered by 24 rockets, to 238 km/h on the AVUS track in Berlin in front of about 3,000 spectators, including film director Fritz Lang and boxing champion Max Schmeling. A month later a rocket-powered rail car, RAK 3, reached 256 km/h near Hanover.

But the team always said the cars were only a warm-up. The real target was flight.

The Glider That Blew Up

Their first attempt used a tailless glider designed by Alexander Lippisch, the Ente. Flown by Fritz Stamer at the Wasserkuppe on 11 June 1928, it became the first full-sized rocket-powered aircraft, completing a circuit of about 1,500 metres. On its second flight, a rocket exploded, punched holes in both wings and set the aircraft on fire. Stamer got it down from about 20 metres and got out. The Ente was a total loss.

Von Opel immediately commissioned a new aircraft from Julius Hatry. The RAK.1 had a sailplane wing with a pod slung underneath for the pilot and sixteen Sander rockets, and a tail carried on booms high above the exhaust.

Take Off Quick

On the morning of 30 September 1929 the flight nearly did not happen. According to historian Frank H. Winter, as von Opel prepared to launch, Major Hellmuth Felmy came up with a warning: a telegram was on its way forbidding all flight tests, so he had better go before it officially arrived.

The first two attempts that morning failed. The launch boosters fired, but the main rockets did not ignite, and the RAK.1 glided back down. The third attempt, at about 3:30 or 4 in the afternoon, worked.

Period footage of the RAK.1 demonstration at Frankfurt-Rebstock on 30 September 1929. Video: German Speeches.

75 Seconds of Rocket Flight

Von Opel climbed to about 30 metres and was timed at around 150 km/h. A gust near the edge of the field forced him down early, after using only part of his rockets. He landed hard. The skid broke and the cockpit floor was torn away, leaving him hanging in his harness. Ten minutes later he wrote down his impressions for The New York Times, which had bought the exclusive American rights.

What Came Next

The RAK.1 flew only once in public, but it did what von Opel wanted. It made rocket propulsion front-page news and helped set off what Wikipedia calls a global "rocket rumble." Within a decade, rocket aircraft were being designed in earnest in Germany, leading to the Heinkel He 176 and the Me 163 Komet. A replica of the RAK.1 is on display at the Technoseum in Mannheim, where Hatry himself supervised its construction.

Another look at von Opel's 1929 flight. Despite the video's title, the RAK.1 was a rocket plane, not a jet. Video: Motor1.

Sources: Wikipedia (Opel RAK.1, Lippisch Ente); Frank H. Winter, as cited by Wikipedia; Heinz Gartmann, as cited by Wikipedia; Technoseum Mannheim. Featured image: Bergfalke2 / Wikimedia Commons, CC BY-SA 3.0