Take a good look at the cover photo. Now imagine it in full color, change the pilot’s helmet for a slightly more aerodynamic model and the cover for the brand new US Air Force uniforms. It seems current or at least just a couple of years old, right? Although it could strain as a more or less primitive prototype of the Volocopter or Joby Aviation eVTOLs, the snapshot was taken towards the middle of the last century and what it shows is not a vehicle designed for logistics or passenger transport, but el HZ-1 AerocycleOnce one of the most promising devices in the US Army for reconnaissance missions.
Around the 1950s, aeronautical engineer Charles H. Zimmerman developed a system that made it possible to build a small, one-man helicopter with the engines installed at the bottom. To guide the ship, the pilot only had to balance the weight of his own body, just as if he were driving a surfboard. The proposal had two great advantages. First, it offered an agile and versatile vehicle. Second, its handling required little instruction. It seemed so simple in theory that it was calculated that with about 20 minutes of practice it would be enough to master it.
Zimmerman’s approach was liked and several private companies showed interest in the development of the “personal helicopter”, including Lackner Helicopters, as recalled by the World of Engineering account on Twitter. In the middle of the Cold War, for the US authorities it was promising and a barbarous opportunity to demonstrate their technological muscle. Baptized as YHO-2 and renamed HZ-1, the first prototypes of the vehicle began to be tested at the end of 1954 with a good taste in the mouth and allowed to make the jump in 1955 to free flights.
As is often the case, however, what worked like a charm on paper did not quite hold up when it was put into practice. As the tests progressed, technicians began to detect problems in the HZ-1. Piloting it was more complex than the army had originally envisioned and, to top it all, the rotors sometimes failed.
The HZ-1 Aerocycle, also known as the YHO-2 and by manufacturer’s designation DH-4 Heli-Vector, was an American one-man “personal helicopter” developed by de Lackner Helicopters in the mid-1950s. #worldofengineering #engineering #aviation #aviationlovers #aviationgeek pic.twitter.com/cyPmRA3Ftq
— World of Engineering (@engineers_feed) April 21, 2019
A couple of accidents and some unsatisfactory tests in the wind tunnel of the Langley Research Center they were enough for the US authorities threw in the towel. It was concluded that the HZ-1 was not up to the task and the project was put in a drawer.
The YHO-2 was by no means the only attempt to equip its soldiers with personal aerial vehicles with direct lift rotors. Another example is the Hiller VZ-1 Pawnee, which like the Arocycle, the pilot was handled with the rocking. Their prototypes did not perform badly, but the army concluded that they were not practical as combat vehicles.
More than half a century later, they remain to be remembered, as museum pieces and the technical display of a military engineering that was sought. new ways to outmaneuver the enemy.