NA Design NA-40 Bongo
Design work of the (formerly Unis, Obchodni Spol, Sro) Bongo began in 1992 followed by model tests in 1993 with construction of a technology demonstrator started in 1996.
A public debut was at Ârno International Machinery Fair 1997 (then called TINTS NA40 and with two-blade main rotor) by the first prototype, OK-CIU. The prototype began 70 hours of tethered hover flights in March 1998, and two further prototypes were completed by mid-1998.
NA Design planed Normal category certification to FAR Pts 27, 33, 34 and 36 by late 2003, subject to finding joint venture Western partner to share certification, manufacturing and marketing costs. In 2002 financial support of US$2.5 million was still being solicited. The project was put on hold in late 2002 while finance was sought but, despite this, a new version, the four-seat NA50, was announced in late 2002.
Nothing further had been heard by early 2003.
The NA Design NA 40 Bongo two-seat ultralight helicopter features a three-blade teetering rotor and pod and boom fuselage with an inverted Y-tail unit. A Cocomo patented anti-torque system eliminates the need for a tail rotor, reducing transmission complexity and operating noise level.
Flying controls were conventional cyclic and collective, with a ducted air anti-torque system. The structure is mainly composites, including the rotor blades. Some aluminium is in the fuselage, otherwise it is a double-curvature monocoque sandwich, with a laminated, vacuum-formed elastomeric rotor head. The landing gear is a tubular twin-skid gear with ground handling wheels. Inflatable permanent or emergency floats are optional.
Power is from two 86kW Prvni Brnenska Strojina PBS Velka Bites ÒÅ 50Â turboshafts, with FADEC and dual ignition. The engines are mounted side by side behind the cockpit with transmission via a combining gearbox. A single self-sealing fuel tank is beneath the engines, with a capacity of 210 litres.
A baggage space is aft of the two seats and gull-wing window/doors are on each side, hinged on the centreline and opening upward. A dual 27V DC electrical systems and external power receptacle are provided.
Rotor diameter: 7.48m
Fuselage length: 6.15m
Height to top of rotor head: 2.35m
Empty weight, equipped: 480kg
Max load on external sling: 250kg
Max take-off weight: 950kg
Never-exceed speed: 280km/h
Max cruising speed: 250km/h
Econ cruising speed: 230km/h
Hovering ceiling IGE: 4,000m
Max range: 500km