01/31/2012. Remarks by Ray Watkins: "SNCASO had produced three 'hot-jet' powered Ariel helicopters under the direction of Dr. Theodor Laufer who had worked with Dr. Friedrich von Doblhoff at Wiener Neustädter Flugzeugwerke (also known as WNF) in Vienna, Austria to produce the Wn 324 helicopter. He was able to draw on that experience to develop a small helicopter which used a 'cold-jet' drive system to drive the main rotor.

The single-seat S.O.1220 Djinn (Genie) had a small open cockpit with the engine mounted immediately behind the cabin and a light open rear frame carrying a horizontal stabilizer with small endplates and a central vane/rudder at its end. A 250 shp Turboméca Palouste IV engine supplied compressed air to nozzles at the tips of the two rotor blades and its exhaust was directed toward the rear control vane for directional control.

The first of two prototypes (F-WCZX c/n 01) of the S.O.1220, which were meant to prove the rotor and control systems, had its maiden flight on January 2, 1953.

They were followed by five two-seat S.O.1221 Djinn prototype aircraft, the first of which (FWGVH c/n 001) flew on December 14, 1953. A class record for altitude (15,660 ft, 4,789 m) was established two weeks later. The ALAT (l'aviation légère de l'armée de terre, army light aviation) soon placed an order for 22 pre-production aircraft for service evaluation trials with the first flying in September 1954. A total of 178 Djinn's were produced of which 100 went to the French Army.

Three of the French evaluation batch, initially test flown in France registered as F-WIFK, F-WIFL, and F-WIFM (c/n 1023/FR.73, 1024/FR.74, 1025/FR.75) were leased by the US Army, as the YHO-1 (s/n 57-6104 to 57-6106), for their own assessment of the first type in the new Helicopter, Observation (HO) class. Delivered at Fort Rucker, Alabama, USA on May 12, 1958, the YHO-1s had additional US military-standard avionics and communications equipment fitted to supplement the very basic cockpit instrumentation.

The Djinn was extremely maneuverable and could take off and land on the back of a small truck. The aircraft was assessed as being well built, easily maintained and a very capable observation platform. Unfortunately budgetary constraints and resistance to procuring foreign-manufactured equipment meant that no production order was placed for the US Army.

Intended to be returned after their assessment, the three aircraft never made it back to France as all three had crashed within a year. 57-6105 crashed at the Transportation Aviation Test and Support Facility on June 11, 1958, while
57-6104 crashed next to the reviewing stand during an air show at Edwards AFB, California, on May 16, 1959.

The third, 57-6106, was severely damaged in an accident, also at Edwards AFB, on December 31, 1958. It was rebuilt and noted at the Department of Aeronautics, San Jose State College, San Jose, California on November 13, 1971. Presently it is on display at the American Helicopter Museum & Education Center, West Chester, Pennsylvania."