Fritz von Opel, the Opel RAK One Rocket Glider, and the Forgotten Frankfurt Flight of September Thirty, Nineteen Twenty-Nine That Planted the Seed of Everything That Followed

On September 30, 1929, a man climbed into a rocket-powered delta-wing glider at Frankfurt-Rebstock airfield and flew it. The flight lasted approximately 75 seconds. It was witnessed by hundreds, photographed, and filmed. The aircraft that made it possible no longer exists. The ideas it proved never stopped flying.

This is the story of the Opel RAK One and the chain of consequences nobody followed closely enough.

From Road to Air: The RAK Experiments Begin

The story does not begin at an airfield. It begins on the AVUS circuit in Berlin in May 1928, where Fritz von Opel and pyrotechnics manufacturer Friedrich Wilhelm Sander attached 12 solid-fuel rockets to a car with no engine and sent it down the straight in front of reporters and photographers.

The machine, called the RAK Two, reached approximately 225 kilometers per hour (140 mph) - faster than any road vehicle in history at that moment. The crowd went insane. The newspapers named him Rocket Fritz.

Von Opel was 31 years old at the time of the Frankfurt flight, heir to the fortune his grandfather had built through the Opel automobile company. He was not an engineer. He was the money and the nerve - the man willing to stand at the intersection of extreme ideas and the resources to actually test them.

The Society That Changed Everything

Von Opel did not work in isolation. The theoretical energy behind the rocket experiments came from a remarkable organization: the Verein für Raumschiffahrt, the Society for Space Travel, founded by German and Austrian rocket enthusiasts in the late 1920s.

Max Valier, an Austrian science writer and founding member, had been corresponding with von Opel about rocket propulsion applications and helped shape the direction of the experiments. Friedrich Wilhelm Sander manufactured the rockets themselves - not aerospace hardware, but high-quality solid-propellant devices built by a craftsman who knew fireworks.

One of the Society’s members at the time was a teenager named Wernher von Braun. That name matters for what comes later.

When the group turned its attention to aircraft, they brought in glider designer Alexander Lippisch. Lippisch was already among the most gifted aerodynamicists in Europe. The aircraft he designed for the rocket experiments featured a delta wing and swept planform that had almost no precedent in the air at that moment. Remember his name.

The First Rocket-Powered Manned Flight (The One Nobody Saw)

The Opel RAK One was not the first rocket-powered manned aircraft flight. That distinction belongs to an event on June 11, 1928 - fourteen months earlier - in the Rhön Mountains of central Germany.

At a soaring competition, a pilot named Friedrich Stamer climbed into a Lippisch-designed aircraft called the Ente (German for Duck) and ignited a pair of Sander rockets. The flight lasted a matter of seconds. One rocket misfired, the aircraft briefly caught fire, and Stamer landed hard but in one piece.

By any reasonable definition, that was the first manned rocket-powered flight in history.

Almost nobody witnessed it. No major press. No cameras. Just a small gathering of soaring enthusiasts watching a duck-winged glider jerk across a mountain valley and come down rough. History did not notice.

Von Opel noticed - and decided to do it right.

The Opel RAK One: Design and Construction

Von Opel commissioned a new aircraft built by Julius Hatry, a skilled constructor who could translate aerodynamic theory into a flyable airframe. The design refined what Lippisch had already demonstrated: a delta wing with no conventional landing gear, built to launch from a wheeled dolly and land on belly skids.

Instead of two rockets, this aircraft would carry sixteen.

Sixteen Sander solid-fuel rockets arrayed along the lower tail section, each capable of significant thrust for a matter of seconds before burning out completely. There was no throttle, no mixture control, no power management of any kind. Once lit, the rockets would burn until they burned out, and everything that happened in between would happen very fast. Von Opel’s only inputs were the stick and rudder.

September 30, 1929: What Happened at Frankfurt-Rebstock

Von Opel had made sure the press was there. Reporters from the major papers. Photographers. Newsreel cameras positioned around the field perimeter. If this worked, the world would know before the evening editions.

He gave the signal. The ground crew lit the fuses.

Sixteen solid-fuel rockets ignited simultaneously. The Opel RAK One launched down the grass in a cloud of white smoke and fire the photographers later said was visible from a kilometer away. The launch dolly dropped behind. Von Opel was airborne.

The acceleration was immediate and violent - not gradual. Within the first few seconds he was moving faster than most powered aircraft of the era could manage in level flight. The delta wings bit. The swept planform did exactly what Lippisch had designed it to do.

For approximately 75 seconds, Fritz von Opel flew a rocket-powered aircraft in a controlled arc over Frankfurt-Rebstock, reaching speeds approaching 150 kilometers per hour (90 mph). Every second was photographed. Every second was filmed.

The rockets burned out. The aircraft became a glider. Von Opel brought it in on its belly skids, slid across the grass, and stopped.

The crowd surged the field.

What the Flight Proved

Unlike the brief, chaotic hop in the Rhön Mountains fourteen months earlier, the Frankfurt flight was clean, controlled, and purposeful. It demonstrated three things the engineering world needed confirmed:

First, that a human being could control a rocket-powered aircraft through sustained flight - not a jerk and a crash, but 75 seconds of deliberate maneuvering.

Second, that the aerodynamics of a swept planform functioned correctly under rocket thrust. Lippisch’s delta wing worked.

Third, that solid propellant could get an aircraft airborne and keep it there long enough to matter.

History credited von Opel as the first rocket pilot. Friedrich Stamer might reasonably contest that. History tends to credit the spectacular rather than the merely first.

The Threads That Run Forward

Max Valier continued his work after Frankfurt, shifting attention to liquid-fuel rockets for more controllable and sustainable thrust. In May 1930, a liquid-fuel rocket engine exploded during a ground test in Berlin. Valier was killed. He was 35 years old. His name is largely forgotten outside specialized rocket history, but the Society for Space Travel he helped found continued without him.

Wernher von Braun continued. The line from those 1920s rocket enthusiasts in Berlin runs in a fairly direct direction to the A-4 rocket - known better as the V-2 - and from there to the Saturn V and every human being who has ever stood on the surface of the moon.

Friedrich Wilhelm Sander faded from prominence when the theorists moved toward liquid propellants. But solid-fuel rockets never went away. The principle of Sander’s propellant-packed steel tubes lives on in jet-assisted takeoff systems, spacecraft escape towers, and the solid rocket boosters that once flanked the Space Shuttle on its climb from Cape Canaveral. The technology grew enormously. The principle did not change.

Alexander Lippisch and the Line to the Me 163

The most consequential thread runs through Alexander Lippisch.

In the late 1930s, the German air ministry needed something specific: a point-defense interceptor capable of reaching Allied bomber formations before they released their loads - something with performance no propeller-driven aircraft could match.

The answer was the Messerschmitt Me 163 Komet.

A rocket-powered fighter. A tailless swept wing. The fastest aircraft in the world when it entered operational service in 1944. The only rocket-powered combat aircraft in history.

When you look at the Komet - its stubby swept wings, its Walter rocket motor burning two propellants so volatile they ignited on contact with each other - you are looking at the direct aerodynamic descendant of the delta-winged glider von Opel flew at Frankfurt-Rebstock in 1929. Lippisch drew a line from the rocket gliders of the experimental era to the most radical interceptor of the Second World War, and it was a surprisingly straight line.

The delta wing worked in 1929. It worked in 1944. It flies on combat aircraft around the world today.

The Man Who Climbed In Anyway

Fritz von Opel was not an engineer. He held no aeronautical degree. He was not a professional test pilot. He was a wealthy industrialist who saw something that excited him and put both his money and his person behind it. He could have funded these experiments from a boardroom and handed the controls to someone else.

He chose not to.

That distinction matters. Aviation history tends to undervalue the courage of the person who does not fully understand every calculation on the chalkboard but climbs in anyway - because they believe the thing is worth doing and are unwilling to ask someone else to take the risk they themselves will not take.

Von Opel survived his rocket flying. He lived until 1971, long enough to watch human beings walk on the moon, long enough to see the aircraft his experiments helped inspire evolve into supersonic jets and spacecraft he could not have fully imagined when he was being chased down the AVUS track by his own rocket exhaust.

What Survives

The Opel RAK One does not survive. No museum holds the original aircraft. The photographs survive. The newsreel footage survives. Some technical documents survive. The machine itself, like so many experimental airframes from the era of wild first attempts, appears to have simply disappeared.

The ideas did not disappear. They flew in a Messerschmitt interceptor over Bavaria. They flew in research aircraft above the Mojave Desert. They flew in every spacecraft that has left this atmosphere on propellant - solid or liquid - from 1961 to the present day.

Ninety-seven years ago today, sixteen rockets lit, and a man flew. The line from Frankfurt-Rebstock runs further forward through time than almost any aviation history book bothers to trace.

Key Takeaways

• September 30, 1929: Fritz von Opel flew the Opel RAK One at Frankfurt-Rebstock for approximately 75 seconds on 16 solid-fuel rockets - the most witnessed and documented rocket flight of the era
• The first manned rocket-powered flight was Friedrich Stamer’s brief hop in the Lippisch-designed Ente on June 11, 1928 - but it was unwitnessed and largely uncredited
• Designer Alexander Lippisch’s delta wing concept, proven in the 1929 experiments, became the direct aerodynamic ancestor of the Me 163 Komet and modern swept-wing combat aircraft
• Max Valier and the Society for Space Travel - the intellectual engine behind the Opel experiments - also mentored a teenage Wernher von Braun, connecting Frankfurt-Rebstock to the Saturn V program
• The Opel RAK One no longer exists, but the solid-fuel rocket principle it demonstrated lives on in JATO systems, spacecraft escape towers, and solid rocket boosters