This ramjet-powered helicopter was of purely Dutch design and the
only Dutch helicopter reaching series production. In 1952 the
engineers Verhage and Meijer Drees started the development for the
SOBEH (a foundation initiating the development and construction of a
rotorcraft), with support from the NVI (Dutch Institute for Aircraft
construction). Their first product was the SOBEH H-1 (not
registered), and Mr. Idzerda conducted initial hovering trails in
October 1954. These test proved unsatisfying and eventually the
prototype was damaged due to ground resonance.
After redesigning and rebuilding the first airframe the type was
designated SOBEH H-2 (PH-NFT, c/n 2001) and flew successfully in
March 1955 with Mr. Greve at the controls. Confidence was high and
for the series-production a new company was founded in October 1955,
the Nederlandse Helikopter Industrie (NHI); the new product became
the H-3 Kolibrie. The first prototype (PH-NHI, c/n 3001) conducted
its maiden flight in May 1956, this time with René van der
Harten as pilot.
The second prototype (PH-NGS, c/n 3002) flew in November 1956, but
was destroyed on April 26, 1957 during ground testing. The first
prototype and two more H-3s (PH-NGT, c/n 3003 and PH-NGV, c/n 3004)
continued the certification trails and the type gained its Dutch type
certificate on March 3, 1958. In total eleven Kolibries were
delivered, seven of them going to Israel. The project was halted in
1961 due to lack of funds, two of the engineers, Mr. Meijer Drees and
Mr. Kuipers, accepted a leading design job at Bell Helicopters.
The Kolibrie was at the time of its maiden flight the only
ramjet-powered helicopter in the world, and despite of the ramjet at
the rotor tips of simple but notable construction, which neutralized
vibration and considerably lessened maintenance. A disadvantage was
the rather high fuel consumption, therefore a trailer was developed
called the "helicar". This allowed the transport of the
helicopter, its fuel and equipment to the working area; with its
boards unfolded it could be used as landing platform. This and the
low flying speed made the Kolibrie suited for agricultural operations.