Among helicopter pioneers Walter Rieseler is forgotten because he died in 1938 at age 47 of a heart attack. The equal of Focke and Flettner, Rieseler's work with coaxial rotors was impressive for the time. He built his first autogyro in 1927 and unlike Cierva's, the blades could be adjusted in flight. But because of oscillation problems Rieseler went to the US to form a company known as PAS and built a fully functional autogyro the WRK. But not satisfied, he came back to Germany in 1934 and started work on coaxial rotor designs. The R.I flew in 1936 at first tethered and then loose. Test pilot Mohn was impressed but overheating of the engine caused some modifications. A test flight was shown to Ernst Udet but unfortunately the helo crashed on the second performance and Mohn suffered broken ribs. Udet was disappointed. Not deterred, Rieseler designed the coupled engine two passenger R.II which was built by 1937 and flew. Mohn again was test pilot. The R.II flew fine until Dec 1937 when the connecting bolts and pylons to the rotor failed and again the helo crashed. Mohn quit and by January 1938 Rieseler had died of a heart attack. All work on the military-proposed R.III remained in design stage and was never built. And so Rieseler disappeared from rotorcraft history. Had he lived, he would have produced Luftwaffe or Kriegsmarine helos as he had more advanced designs of R.IV and R.V. Not to be...

R.I: http://paralympic-ph.com/germanvtol/rieslerfolder/r1_flight.jpg http://paralympic-ph.com/germanvtol/rieslerfolder/riesler3.jpg http://paralympic-ph.com/germanvtol/rieslerfolder/rieseler4.jpg R.II: http://paralympic-ph.com/germanvtol/rieslerfolder/rieseler2.jpg