Yuri I - Precursor Projects

Before Akira Naito and the Nihon Aero Student Group (NASG) succeeded in lifting off officially with the Yuri I, they went through a series of different designs. The details of these projects is described in articles by Akira Naito such as this one.

Tests

A small scale coaxial rotor in ground effect.
A large single rotor in ground effect.

1. A Day Fly

Diameter: 20.2 m (66.3 ft)
Blade area: 23.0 m² (247.6 ft²) 
Weight: 343 N (77.1 lbs)

2. Papillon A

Diameter: 19.6 m (64.3 ft)
Blade area: 25.0 m² (269.1 ft²)
Weight: 412 N (92.6 lbs)

3. Papillon B

Diameter: 19.6 m (64.3 ft)
Blade area: 25.0 m² (269.1 ft²)
Weight: 412 N (92.6 lbs)

4. Papillon C

Diameter: 24.0 m (78.7 ft)
Blade area: 19.3 m² (207.7 ft²)
Weight: 314 N (70.6 lbs)