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Focke-Achgelis Fa-223 Drache

Avia UR-1
SNCA du Sud-Est SE.3000


Fa223-1

 

At the outbreak of WW2 Heinrich Focke created the twin-rotor Fa223 helicopter. The Fa 223 was fundamentally an extension of the concept which had produced the smaller Fw 61 and employed a generally similar arrangement of twin counter-rotating rotors mounted on outriggers from the main airframe and driven by a fuselage-mounted radial engine. In the Fa 223 the engine was installed amidships in the fabric-covered steel-tube fuselage to the rear of the 4-seat passenger compartment. The forward part of this cabin was a multiple-panelled enclosure made up of flat Plexiglas panels, and the aircraft was fitted with a tricycle undercarriage.

The fuselage of the Fa 223 was divided into four compartments, these being the extensively-glazed nose cockpit which afforded an excellent view for the pilot and observer, the load compartment with starboard entrance door and self-sealing fuel and oil tanks, the engine compartment and, last, the tail section. The fuselage structure was of welded steel tubes, and fabric covering was used except for the metal panelling of the engine compartment. The engine was a 1,000hp BMW Bramo 323 Q3 Fafnir (later redesignated BMW 301R) with a supercharger and cooling fan and, together with a gearbox, was mounted as one unit in two rings, which in turn were attached to the four longitudinal fuselage members by adjustable cables. Struts prevented fore and aft movement of the engine. The front fireproof bulkhead of the engine compartment was separated from the rear wall of the load compartment by a 0.20m gap. This gap was open at the top and sides of the fuselage, with a wire mesh covering, and engine-cooling air was drawn in through this gap and exhausted from an annular opening behind the rear edge of the compartment panelling. Engine exhaust was piped out through the fuselage roof and ejected aft.

Tubular-steel outriggers extended from the fuselage sides to support the two rotor heads, the centres of which were 12.5 metres apart. Power from the engine was transmitted via a friction plate clutch to the gearbox and then by long hollow shafts to the rotor head gears, the lower end of the starboard shaft having a rotor brake and both shafts having a stabilizing friction clutch at their centres to damp any tendency to whip. The total reduction between engine and rotors was 9.1:1, the normal speed of the rotors being 275 rpm.

The rotor axes were inclined inwards by about 4.5° and slightly forwards, and each rotor head had a free-wheel device to allow the rotors to revolve in the event of the drive transmission jamming. Flapping and dragging hinges were provided for the rotor blades, the drag hinges having friction dampers, and inertia dampers reduced vibration in the cyclic pitch control. Each blade consisted of wooden ribs attached to a conically-drawn high-tensile steel tube, the covering being a mixture of plywood and fabric.

The orthodox fin and rudder was surmounted by a strut-braced tailplane which was adjustable for longitudinal trimming only. Hydraulic brakes, operated from the rudder pedals, were fitted to the mainwheels only, and the nosewheel was self-centring and could turn through 360°.

The control column was used to give longitudinal control by equal cyclic-pitch change of the rotor blades, and lateral control by differential collective-pitch change of the rotor blades. The rudder pedals were used to give yaw control by differential cyclic-pitch change of the rotor blades, the control effect being increased by use of the rudder during forward flight. A trimmer wheel was provided for tailplane adjustment, and all control links were by cables. Two machines (numbered 13 and 16) were experimentally fitted with a separate collective-pitch lever next to the throttle, and a throttle governor to maintain a constant engine speed, but this arrangement was under development only. On all other machines, the pilot had a lever with only two positions for collective pitch, one for powered setting and one for autorotation. In addition, an automatic device adjusted the tailplane and altered the blade pitch from the powered setting to the autorotation setting for a glide landing in the event of a power failure, but the pitch could not be reset in the air. Thus, apart from pitch adjustments for attitude control, the rotors must be regarded as having had a fixed pitch, the lift being controlled by the engine throttle. This fact reduced the safety, handling, and performance characteristics and, in order to maintain a constant rotor speed during a climb, progressive engine throttling was necessary and this cancelled out the benefits of an engine supercharger. Considerable skill and experience was also necessary during hovering and low-speed flight because of the very sluggish lift control; more than one Fa 223 was lost when making downwind turns at low level.

After 100 hours' ground running, and tethered hovering tests, the Fa 266 made its first free flight in August 1940, by which time it was redesignated Fa 223 Drache. Manufacturer's trials with the Fa 223V1 revealed slight instability at the lower end of the speed range, but the helicopter's general handling and controllability were excellent and on 28 October 1940 D-OCEB was flown to a record height of 7100m. The machine was to be tested in these roles using 30 pre-production Fa 223s, which the RLM ordered from the Focke Achgelis Bremen factory.

Most of the equipment required for the various roles the Fa 223 was to perform could be fitted to or removed from the basic machine. For all roles except training, an FuG 17 radio, FuG 101 radio altimeter, nose-mounted MG 15 machine-gun, and an observer's seat were fitted. Additional equipment required was a rescue cradle, winch and electric motor operating through the fuselage floor, for reconnaissance and rescue; a hand camera pointing through the cockpit floor, for reconnaissance and anti-submarine duties; a jettisonable 300 litre (66 Imp gal) auxiliary fuel tank, for reconnaissance; fuselage racks and two 250kg bombs for anti-submarine work. For cargo transport a load-carrying beam was used to carry heavy or bulky loads suspended beneath the helicopter by cable, which had a pilot-operated, electric quick-release mechanism at its lower end. The maximum load actually carried by an Fa 223 by this method was 1,280kg, which was greater than by any other contemporary helicopter. However, carrying loads suspended by cable proved tiring for the pilot on long flights, and, during troop-supplying trials, stabilizing surfaces fitted to the loads were found to give some improvement. The remaining equipment which could be fitted was a Luftwaffe dinghy stowed in the tail section, respirator racks and, for training purposes only, dual controls.

 

Fa223-2

 

Of the 30 pre-production Fa 223s ordered from Bremen, only ten or eleven were completed before the factory was bombed, destroying other machines in various stages of construction, and in total they flew about 400 hours, including about 9,985km of cross-country flying. The firm then moved to Laupheim, near Stuttgart, where seven more Fa 223s were built. Early in 1942, the Fa 223 was considered ready for operational testing, and trials began, although by July 1942, because of constant losses and setbacks caused by bombing, only two machines had actually flown. Successful trials with the Fa 223, primarily in the assistance of troops, resulted in the ordering of 100, but only eight were test flown, and six of these were destroyed by bombs in July 1944 at Laupheim. Once again a new production factory was established, in Berlin, with a production capacity of 400 aircraft a month, but only one was completed by the end of the war. The maximum flying time, in Germany, on any one machine was about 100 hours.

The fate of one Fa 223 (No. 12) is perhaps particularly interesting; this helicopter, after completing a long cross-country flight from Germany, was flown to Mont Blanc to perform a mountain rescue of 17 people trapped in the snow. Unfortunately, a mechanical link failure resulted in a rotor disintegrating, and, although the machine touched down on its wheels, it was hurled against an embankment and the crew was killed.

It is known that the few machines available were used on a small scale in general transport and communication work, Luft-Transportstaffel 40 having three Fa 223s on hand at Ainring in April 1945. It was probably these three machines which were the only ones serviceable at the end of the war, and one of these was finally destroyed by its pilot. The remaining two (Nos. 14 and 51) were taken over by American Forces at Ainring in May 1945 for evaluation. One Fa 223 (No. 14), which had first flown in July 1943, was flown by its German crew (consisting of the pilot H. Gersenhauer, the engineer H. Zelewski, and the mechanic F. Will) to England and made history by being the first helicopter to cross the English Channel. It arrived at Brockenhurst, Hampshire, in September 1945 and began flight trials but was destroyed the following month, having had a flying life of 170 hours. The accident occurred when the automatic pitch change mechanism malfunctioned and switched the rotors to the autorotation condition. Since this occurred when the Fa 223 was hovering only about 20m from the ground, it had neither the altitude nor the forward speed for an autorotative landing.

 

Three known examples were completed after the end of World War 2, all from captured or salvaged components. One of these was built, with the assistance of Doktor Heinrich Focke, by the SNCA du Sud-Est in France with the designation SE.3000 and flown on 23 October 1948. Registered F-WFDR, power was by one 1000hp BMW-323-R2 engine.

 

Sud-Est-SE3000
Sud-Est SE.3000

 

The other pair, designated UR-1, were built at the Ceskoslovenske Zavody Letecke (formerly Avia) factory in Czechoslovakia. A start was made on helicopters in the autumn of 1945 by reconstructing two Fa 223s from salvaged parts, the resulting machines being more or less standard.

 

Uncompleted German wartime projects included proposals to produce a 4-rotor helicopter by joining two Fa 223's together in tandem with a new fuselage centre-section; and the much larger Fa 284 crane helicopter to be powered by two 1600 or 2000hp BMW engines and capable in the latter form of lifting a 7000kg payload.

 

Fa 223
Engine: 1 x BMW 301R, 746kW
Rotor diameter: 12.0m
Fuselage length: 12.25m
Height: 4.35m
Width with rotors turning: 24.5m
Max take-off weight: 4310kg
Empty weight: 3175kg
Max speed: 175km/h
Cruising speed: 120km/h
Ceiling: 2010m
Range with external fuel tanks: 700km

 

 

 


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