RAK BOB
RAK BOB was the name given to a rocket-propelled sled that Max Valier experimented with in the late 1920s.
RAK BOB I.
The world's first test drives with a rocket sled took place on January 22, 1929 at the Schleissheim airfield . RAK BOB I was used for this. Valier designed this sled himself and had it built by the Kogel body shop in Munich . The hull of the vehicle consisted of an ash wood construction that was planked with sheet metal. It was 6 meters long and 40 centimeters wide; the runners had a length of 2.2 meters and a width of 15 centimeters. Valier, supported by friends, paid 600 Reichsmarks for the RAK BOB I.
During an unmanned test drive, RAK BOB I reached a speed of 110 km / h and drove 130 meters. It was propelled by eight 50 mm ice field powder rockets, each developing 11.8 kN of thrust . Valier was able to afford a total of ten of these missiles for the test day, so that on the second attempt only two were available. With Valier on board, the rocket sled drove only 40 meters over the snow this time and reached about 35 km / h. The vehicle was slightly modified after these two test drives.
RAK BOB I was presented to the public on February 3, 1929. At the winter sports festival of the Bavarian Automobile Club, the rocket sled drove over the frozen Eibsee . On the first trip, Valier's wife Hedwig was in the cockpit. RAK BOB I was propelled by six rockets, which were detonated in pairs at an interval of two seconds. At a speed of 45 km / h, a distance of 100 meters was achieved. For the second run, which Max Valier wanted to do himself, RAK BOB I was equipped with twice as many rockets. But there was no success; at a speed of almost 100 km / h one of the rockets burst, the others were damaged and the sled lost speed. Max Valier was able to get out of the vehicle unharmed, but the planned third trip had to be postponed.
RAK BOB II
Max Valier used the compulsory break between February 3rd and 9th, 1929, when he was supposed to show his sled again in public in order to redesign the vehicle again and to make the successor RAK BOB II out of RAK BOB I. RAK BOB II had its premiere on the frozen Lake Starnberg . At an ice festival in front of the UNDOSA pool, it was initially launched unmanned, propelled by 18 rockets. The sled reached a speed of almost 400 km / h, but deviated from its intended path, rammed a landing stage and was badly damaged. Max Valier did not have the financial means to continue his experiments with the rocket sled. RAK BOB II was later given to the Deutsches Museum . Together with Valier's RAK 7 rocket recoil test vehicle, he is there in the space department.
The role of the rocket sled in Valier's research
Max Valier saw RAK BOB I and II as necessary intermediate stages to his actual goal, the space rocket. When he was experimenting with the rocket sled, he had already seen Fritz von Opel's experiments with rocket-propelled road vehicles and used them to plan the rocket-propelled rail vehicle that was supposed to reach higher speeds. Valier later wanted to expand his experiments from rocket-propelled ground vehicles to airplanes, such as the Junkers G 24 propeller plane, then develop rocket stratospheric aircraft with intercontinental range and finally wingless rocket spacecraft. However, differences soon arose with Fritz von Opel and Valier had to look for a new financier.
Valier's last research
After falling out with Fritz von Opel, Max Valier worked with Werner Meyer-Hellige from JF Eisfeld's powder and pyrotechnic factories in Silberhütte . This resulted in two rail vehicles, the Eisfeld-Valier RAK 1, which derailed and destroyed during a test run in July 1928, and the RAK 2, which also broke during a test run. Valier, who had refused to equip the vehicle with 36 copper case rockets and saw himself confirmed by the accident, ended his collaboration with the Eisfeld factories and decided to finance his next experiments on his own.
Both his successes with RAK BOB I and II as well as the press reports about Fritz Stamer's first flight with a rocket- powered aircraft on June 11, 1928 reinforced Valier's endeavors to further develop rocket-powered flight. Together with Gottlob Espenlaub , he first experimented in the summer of 1929 with an aspen leaf EA 1, which was only temporarily converted, which was now called Valier-Espenlaub RAK 3. After struggling with a financial bottleneck, Espenlaub separated from Valier and continued to work alone. On October 22, 1929 he succeeded in his first test flight, but on the second he had to jump out of the plane, which had caught fire from an exploded rocket, and was seriously injured.
In the meantime, Valier had a recoil test vehicle built by Möllers in Essen , which was called the RAK 4. This vehicle was supposed to pave the way to a fully functional liquid engine. It had a carbonic acid steam jet recoil engine and was successfully demonstrated in public several times by Valier from autumn 1929. Supported by Paul Heylandt, who owned the company for industrial gas utilization, Valier was able to record successes with new engines and vehicles and in the spring of 1930, on the occasion of a successful test drive with the Valier Heylandt recoil test vehicle RAK 7, presented his ideas for a stratospheric high-speed airliner to the press. A fatal injury to his pulmonary artery caused by a splinter when a combustion chamber exploded in the laboratory put an end to these hopes that same spring.
The research results that Max Valier achieved with the RAK BOB I and II and all of his other test vehicles later fell into the hands of the Reichswehr .
Web links
- Detailed description of the history of Valier and his vehicles
- Overview of the development of rocket technology with numerous pictures (PDF; 7 MB)
- Obituary for Max Valier