The Nederlandse Helicopter Industrie H-3 Kolibrie is a two-seat light utility and observation helicopter, utilising a ramjet-powered rotor of unique design. In October 1955, NV Nederlandse Helicopter Industrie (N.H.I.) was founded by the Maatschappij voor Vliegtuigbouw Aviolanda NV, Papendrecht, and NV Kromhout Motoren Fabriek, Amsterdam. N.H.I. was established to continue the helicopter development work started by the SOBEH and to start serial production of ramjets helicopters. SOBEH "Stichting voor de Ontwikkeling en Bouw van een Experimenteel Hefschroefvliegting" (Foundation for Development and Manufacturing of an Experimental Helicopter) was established in the early 1950's to research and build small ramjet-powered helicopters designed by J. Meyer Drees. SOBEH developed and built two helicopters: the SOBEH H-1 and H-2. The H-1 was an open-frame single-seat machine with two small ramjets fitted at the tips of the two-blade rotor and a skid undercarriage. The H-1 was built in Nederhorst den Berg and moved to Rotterdam Airport Zestienhoven where it was tested in 1954. The H-1 never flew as it rolled over during the groundtests. The H-2 was an improved version with a large windshield and a tiny strutted tail unit with a small anti-torque propeller. In March 1955, the SOBEH H-2 briefly got off the ground, but the first real test flight was on 9 November 1955. After having met its goal of developing a helicopter, SOBEH ceased activities and further development and serial production were granted to the newly formed Nederlandse Helicopter Industrie. The SOBEH H-2 c/n 2001 PH-NFT was taken over by the Nederlandse Helicopter Industrie N.V., Rotterdam, and they refined the design into the two-seat NHI H-3 Kolibri. The NHI H-3 Kolibri has a duraluminium tube superstructure, an open cockpit and an undergear of metal skids with two ground-handling wheels. Two ramjets, one at the tip of each rotor blade, power the helicopter. The small tail rotor is powered by the motion of the main rotor. The Kromhout NHI TJ-5 ramjets could run at any given fuel, like gasoline, kerozine and petroleum. As a starter of the helicopter a two-stroke "Puch" moped engine was used. In 1956, production of three prototypes started Rotterdam Zestienhoven, with NHI's two associate companies, Aviolanda and Kromhout, producing the airframes and rotor heads respectively. Kromhout also build the ramjet engines, while the rotor blades were manufactured by Fokker. On 3 July 1956, the first prototype NHI H-3 Kolibrie, c/n 3001, was registered PH-NHI. In 1957, the production of an initial series of five Kolibries started, in 1958 followed by a second batch of five. On 3 March 1958, the Kolibrie received a Certificate of Airworthiness based on the U.S. requirements for rotorcraft. In March, 1958, deliveries of the NHI H-3 Kolibrie began with the first one c/n 3006 as PH-YMP going to the Directie v/d Wieringermeer (NOP-werken), Zwolle. Next to the Netherlands, the NHI H-3 Kolibri was operated in Western Germany, Israel, Dutch New-Guinea and the UK. The N.H.I. H-3 Kolibrie was mainly used as an agriculture spray helicopter for which it could be fitted with 15.00m spray booms. Because of its high fuel consumption the Kolibrie was uneconomical to fly on nonproductive flights, and a special mobile helicopter platform was developed to transport the Kolibrie by road. In 1961, production of the H-3 Kolibrie ended with three prototypes and eight production machines completed. The high fuel consumption of both ramjets and the noise, the Kolibrie was heard to 5 kms away, killed further commercial development.