|Flettner Fl 282 "Kolibri"|
The pioneer work of Anton Flettner is often overshadowed by the more publicised activities of his contemporaries Focke and Sikorsky; yet Flettner's first fully practical helicopter, the Fl 265, was far superior to the Fw 61 and made a successful free flight several months before the VS-300 began tethered flights. Flettner's first rotorcraft, flown in 1932, had a 2-blade rotor 29.87m in diameter, with a 30hp Anzani engine mounted part of the way along each blade driving a propeller - a form of propulsion similar to that used by the Italian Vittorio Isacco on his so-called 'helicogyros' developed in the U.S.S.R. in the 1930s. The Flettner machine made a successful tethered take-off, but later overturned during a gale and was written off. His next significant design was the Fl 184 single-seat autogyro; powered by a 150hp Sh.14 radial engine, it flew in 1935 and was due to be evaluated by the German Navy when it, too, was unfortunately destroyed. The next design was the Fl 185, whose prototype (D-EFLT) flew in 1936 and had a 3-blade main rotor. The centrally-mounted Sh.14A engine drove, in addition to the rotor, two small anti-torque propellers on outriggers each side of the cabin and a large cooling fan in the nose.
By this time, however, Flettner had developed the idea of counter-rotating, intermeshing twin rotors. Many of his advisers thought that the airflow disturbed by the intermeshing blades would make this system less efficient than one using a single rotor; but Flettner believed that any problems thus encountered would be more than offset by the reduced drag resulting from having no external rotor-carrying structure. He proved his point by installing such a system in the Fl 265, whose prototype (D-EFLV) flew in May 1939. At this time encouragement for the development of small helicopters came mostly from the German Navy, on whose behalf six Fl 265's had been ordered in 1938 with a view to developing a machine suitable for shipboard reconnaissance and anti-submarine patrol. Service trials of the Fl 265 were more than satisfactory, and plans were made for series production; but by this time work was well advanced on a later model, the Fl 282, which could carry a men and was more versatile. The RLM therefore agreed to wait for the Fl 282, to hasten whose development it ordered thirty prototypes and fifteen pre-production aircraft in spring 1940. Maiden flight was made in 1941. The first three prototypes were completed as single-seaters and had fully enclosed cabins made up of a series of optically flat Plexiglas panels, faired-in rotor pylons and well-contoured fuselages. The Fl 282V3 was fitted with endplate auxiliary fins and a long underfin beneath the rear fuselage. Later machines had more utilitarian bodies and some had semi-enclosed cockpits; others, like the example illustrated, had a completely open pilot's seat.
Like the Fl 265, the Fl 282 underwent exhaustive service trials, and several were used operationally from 1942. Usually they flew from platforms above the gun turrets of convoy escort vessels in the Baltic, Aegean and Mediterranean, often in extreme weather conditions, and revealed control and performance qualities well above expectations. By VE-day, only three of the twenty-four prototypes completed by Flettner at Johannisthal still survived, the others having been destroyed to prevent capture. Two of these, the V15 and V23, were taken to the United States, and the other to the Soviet Union. The RLM had placed an order in 1944 for one thousand Fl 282's from BMW, but Allied bombing attacks prevented production from being started.
At least two other Flettner helicopters were under development when the war ended. These were the Fl 285, another fleet spotter with an Argus As.10C engine, capable of making a 2-hour flight and carrying two small bombs; and the Fl 339, a large transport helicopter project powered by a BMW 132A engine.
K.Munson "Helicopters And Other Rotorcraft Since 1907", 1968
The Flettner Fl 282 Kolibri was designed from the outset as a two-seater, so that, at the expense of range, an observer could be carried, with obvious benefits in the roles of army and navy spotting and anti-submarine work. The observer was to be accommodated in a seat facing rearwards and positioned behind the rotor shafts, and the design provided for a permissible c of G travel which allowed the helicopter to fly with or without the observer without trim changes. The design was finalized by about July 1940 and work began on 30 prototypes and 15 pre-production machines at Flettner's Johannisthal and Bad Tolz factories. For early flight trials, which began in 1941, the first three Fl 282 prototypes were built as single-seaters and had enclosed Plexiglas-panelled cabins, but subsequent machines were built as open two-seaters.
Departing from previous Flettner practice, the 160hp BMW Bramo Sh 14A radial engine was mounted in the centre of the fuselage, thus providing the pilot with an excellent forward view. Cooling air for the enclosed engine was drawn in through openings beneath the fuselage by a wooden fan, and a high pressure air tank was connected to the engine cylinders through a distributor for starting. On the forward end of the engine crank-case was mounted a transmission unit which changed the direction of drive from horizontal to upward and aft by 65 deg. A drive-shaft with universal joints then took the drive from the engine transmission unit to the upper transmission unit, which consisted of gears and shafts connecting the two rotor shafts. The final cross-shaft between the two rotor shafts was fitted with a free-wheeling unit to disconnect the engine drive, and also with a rotor brake. On the drive-shaft from the engine, a friction disc clutch was fitted which was used for running up the rotors until there was no slippage, when a positive dog-type clutch, on the same shaft, was then engaged. Total reduction through all the transmission units was 12.2:1.
The two two-blade rotors, which were synchronized to be parallel in the 45° position, were mounted on shafts having an included angle of 24° between them and an inclination forward of 6°. The rotor blades consisted of wooden ribs mounted on tubular steel spars with a covering of plywood followed by fabric. Flapping and dragging hinges were fitted, the latter having friction dampers. A centrifugally-operated blade-pitch governor held the rotor rpm within prescribed limits, the governor being driven through clutches from the rotor transmission. In order to ensure that power-off autorotation was not lost, the governor was set for a minimum rotor speed of 160 rpm. With the use of his collective-pitch lever, the pilot could over-ride the governor but only to increase rpm. Under certain conditions, self-excited oscillations could occur in the rotor; this pheno menon happened in flight on one occasion when an Fl 282 was being flown with a high collective pitch and the low rotor speed of 140 rpm (compared with the recommended 175 rpm). Vibration became so severe that the pilot prepared to bale out, but, before he could do so, the machine went into autorotation and the vibration ceased.
At the rear end of the fuselage, a horizontal stabilizer was provided for trimming purposes and a fin and rudder of very generous area. This large area was necessary because much of it was ineffective due to the poor aerodynamic shape of the fuselage causing rearwards flow separation and turbulence. Steering of the Fl 282 was by a combination of the rudder and differential collective pitch change on the two rotors, but only the rudder could give steering during autorotation since collective pitch was then ineffective (another reason for the large rudder area).
The fuselage consisted of a welded tubular-steel structure with metal panelling enclosing the centre (engine) section and fabric the rear section and vertical surfaces. The undercarriage was of the non-retractable tricycle type with the nosewheel connected to the rudder pedals for steering.
The Fl 282 was more highly developed and flew more hours than any other German helicopter, and very extensive tests and measurements were made of all flight aspects. Most of this test work was done by Flettner's chief pilot, Hans E. Fuisting, who also undertook blind flying and trained many of the 50 pilots who learned to fly the Fl 282. Some new pilots ran into trouble when flying near the ground, because, as they turned with the wind, they lost lift and struck the ground. One new pilot had a fatal accident when flying his Fl 282 blind in cloud, and the assumed cause of the accident was that the machine had been dived and the controls then pulled back so violently that the blades were forced into each other or into the tail. The diving speed thereafter was restricted to 175km/h. On occasions, the Kolibri was landed autogyro fashion and without the use of collective pitch. This was done by descending vertically, diving nose-down and then pulling back on the controls to land, but, on one occasion at least, the tail hit the ground and was damaged.
Extremely manoeuvrable and very stable, even in gusty conditions, the machine could be flown hands-off in forward flight above 60km/h for indefinite periods by making an adjustment to neutralize the loads on the controls. However, in forward flight at speeds below 60km/h there was some longitudinal instability which reached a maximum at about 40km/h. Another slight criticism of the Fl 282 was that it vibrated rather badly while the rotor was running up on the ground, but this vibration decreased upon lifting off, although there was still a certain amount of vibration transmitted to the control column, which was sluggish and tended to overshoot the requisite amount of movement. Although many of the mechanical components were unnecessarily complicated and heavy, the general design and workmanship were of excellent quality, and, as an endurance test, one machine was flown 95 hours in all without replacements or repairs. The engine, which had a long development history, was said to be capable of 400 hours between overhauls.
Beginning in 1942 with the Fl 282 V5, the German Navy held a series of trials in the Baltic, the machine behaving well under the worst weather conditions. The Fl 282s in these trials operated from a platform mounted on one of the gun turrets of the cruiser Köln, and, on at least one occasion, a landing was made in very heavy seas. By 1943, twenty Fl 282s had been built and some were used for convoy protection in the Mediterranean and Aegean. Unfortunately, little is known of the operational employment of the machine, although it is known that Luft-Transportstaffel 40, based at Ainring in April 1945, had at least three Fl 282s (and also three Focke Achgelis Fa 223s) at its disposal. It was possibly one of this unit's Fl 282s that flew Gauleiter Hanke out of besieged Breslau just before the capture of that city.
The great success of the Kolibri, which was even better than the Fl 265, resulted in a production order for 1,000 machines being given in 1944 to the Bayerische Motorenwerke (BMW), which prepared the requisite tooling-up only to have production forestalled by Allied bombing of the Munich and Eisenach works. The Flettner Johannisthal factory was also bombed, and, by the end of the war, this concern had completed only 24 prototypes in all. Of these, only three were discovered by the Allies in a serviceable condition for testing, the Fl 282 V15 and V23 being taken to the USA and a third machine to the USSR. Examples known to have survived are the Fl 282 (c/n 28368) at the Cranfield Institute of Technology, and the Fl 282 V23 at the United States Air Force Museum, Dayton, Ohio.
During 1944, when the Fl 282 was considered fully developed, Anton Flettner turned to the design of the Fl 339, using all the experience gained with the Fl 282. The Fl 339, which never got beyond the project stage, was to have been a much larger helicopter weighing some 3,000kg empty, carrying about 20 passengers and being powered by a single engine.
J.R.Smith, Antony L. Kay "German Aircraft of the Second World War", 1972
In December 1934 talks were held by the development group of the RLM (LC II) in the presence of State Secretary Milch which were to lead to important decisions concerning future air armaments.
The following is noted in the minutes under Section 4 "Rotary Wing Aircraft": "The development of rotary wing aircraft is to receive preferential treatment. Consequently all work now under way is to be accelerated, as these aircraft will presumably be of significance for land and sea use in the future."
This prognosis wasn't fully vindicated until the many military conflicts after the Second World War, especially Korea and Vietnam. Now the helicopter is also an integral part of the civil aviation sector, especially in the air rescue field. Over the course of time the technology associated with this type of aircraft has been much improved. Back then, however, the field of helicopters, their development and design as well as the basic research in this area, were absolutely uncharted ground for the technicians and designers.
In the LC II.1’s general working plan (Dec. 1935) "rotary wing aircraft" appeared under the heading: "Sport, basic training, advanced training and special aircraft" (Report II/1a). The following types are listed: Fi 184, Fw 61, Focke Wulf project (the later Fw 186) and LC 30 Focke-Wulf license.
The C 30 will be discussed briefly because the navy was already interested in using it as a shipboard aircraft. The C 30 was a pure autogiro design by the Spaniard Juan de la Cierva from the year 1933. Concerning license manufacture of the type by Focke-Wutf, it is to be noted that Focke-Wulf did not obtain rights to produce the C 30 under license in 1933 as was claimed in a recent publication on helicopters. License negotiations began in February 1935, initially with the "Hamburger Flugzeugbau G.m.b.H" (abbreviated Ha, later Blohm und Voss), however these collapsed for financial reasons. Focke-Wulf entered the negotiations in July 1935. The start of license construction by Focke-Wulf was delayed on account of currency exchange difficulties until December 1935, when the exchange rate was guaranteed for 36 examples of the C 30.
Preliminary shipboard trials with the C 30 autogiro began on November 10, 1936 at E-Stelle See (Naval Test Station) Travemünde. The trials ended unsatisfactorily as a result of the type's inadequate performance, its less than satisfactory handling characteristics in gusts and the poor view offered the pilot during deck landings on small platforms. Further development of the C 30 for military use was therefore abandoned.
The following brief history of Anton Flettner's developments in the field of helicopters is included here to provide the reader with a summary of his work.
Anton Flettner (1885-1961) made a name for himself in 1917 as the inventor of the "Flettner Tab." Another of his ideas was the "Flettner Rotor," a means of propelling a ship by wind, which was not a success.
Flettner began work on his first experimental helicopter at the beginning of the nineteen-thirties. Arranged over a relatively small fuselage was a twin-blade rotor of 30.5 meters diameter; the blades were supported by bracing wires extending from a bracing tower above the rotor axis which rotated with the rotor. A 30hp Anzani engine driving a puller propeller was mounted rather far outboard on each blade. As a result of this direct drive of the rotor blades there was no torque moment to compensate for. Fuel was drawn from a tubular tank mounted fore or aft of the engine.
The prototype, of wood and plywood construction, was built by "Segelflugzeugbau Edmund Schneider" of Grunau in 1934. It crashed the same year while in tethered flight.
In January 1935 Flettner received a development contract from the RLM for an "experimental autogiro" (autogiro with three-blade rotor). Three so-called "SV-Types" were planned. Inspection of the mockup took place in June 1935. Only one prototype, the Fl 184 V1 D-EDVE was built. The aircraft was destroyed as a result of pilot error in the course of its maiden flight in December 1936. The Fl 184's external shape still exhibited a certain similarity to the C 30 autogiro being built under license by Focke-Wulf at that time. Power was provided by an Sh 14 engine driving a conventional propeller.
The development contract for the Fl 185 was issued by the RLM in February 1937; two SV-Types were planned. It was given the designation "Helicopter Conversion 184" in the Aircraft Development Program, because the planned Fl 184 V3 was used in the construction of the Fl 185 V1. The project was financed with the insurance sum received from the destroyed Fl 184 V1 and a grant of approximately RM 50,000 from the RLM. Mockup inspection took place in April 1937.
The Fl 185 was a gyroplane equipped with a three-blade rotor; torque balance was achieved by means of variable-pitch pusher propellers driven by extension shafts located at the ends of outriggers mounted on each side of the fuselage. The starboard propeller produced backward thrust, the port forward, so that the total moment exerted on the fuselage balanced that of the main rotor.
The sole prototype built was the Fl 184 V1 D-ELFT, which carried out a number of flights m 1938. Results were favorable, although all tests were made in close proximity to the ground.
The future concept of the Fl 282 was apparent in the Fl 265, which was conceived and designed in 1938. The Fl 282 exhibited significant improvements compared to preceding designs, for example the double rotor with intermeshing blades, automatic changeover from helicopter to autogiro flight (autorotation, from the V4), and the ability to switch back to helicopter flight. Six prototypes were built (Werk-Nr. 1579 -1584), one of which (TK+AN) was tested in the large wind tunnel at Chalais Meudon (Paris) in the summer of 1940.
The Fl 265 V1 D-EFLV took off on its maiden flight in May 1939 in the hands of Flugkapitan Richard Perlia following an extensive series of ground tests (first full-power run on 17.01.1939, first tethered flight at a height of 20 cm on 14.03.1939). It was also used for extensive military testing in conjunction with the Kriegsmarine (for example deck landings on an approximately 25-meter-square landing platform on the cruiser Köln). The aircraft was removed from service on April 29, 1940.
The Fl 265 V3 crashed due to pilot error on August 21, 1939 and was destroyed in the ensuing fire. The Fl 265 V5 (retired on 26.11.1941) and the Fl 265 V6 (retired 25.03.1942) were still on hand at the Flettner Company in November 1942. Their return to service was postponed and eventually abandoned.
All the Fl 265 prototypes accumulated the following in the course of testing: pure flight time 126 hours, 32 minutes; takeoffs 1.180; running time 518 hours, 44 minutes (flight time + tethered flights + engine run-up time). At the time this represented a record number of hours of operation for a helicopter.
The Fl 282 was undoubtedly Anton Flettner's most successful helicopter development. Today one can say without exaggeration that it was the best helicopter of its day.
The exact date on which the RLM issued the development contract for the Fl 282 is not known. It can be assumed with certainty, however, that design work was begun in 1939 while testing of the Fl 265 was under way. All the test results and experience from the Fl 265 were applied to the design of the Fl 282.
By mid-August 1941 work on the Fl 282 V1 had progressed to the point where it could be used on the ground as a transmission unit test bed. The test bed was anchored but could climb the length of the restraint to a certain height and hover. 125 hours and 39 minutes were spent in these tests, which lasted until November 21, 1941. In the event of the destruction of the V1 or a lengthy interruption of testing due to some other problem, it was planned to use the Fl 282 V4 as a replacement test bed.
The first free flight was made by the Fl 282 V2 on October 30, 1941. At the controls was test pilot Ludwig Hoffmann, who had joined Flettner as the successor to company pilot Perlia. Tests resumed in March 1942 following design changes to the cardan shaft; the tests revealed a significant improvement in the helicopter’s handling. The Fl 282 V2 was taken out of service on May 25, 1942; the aircraft's transmission and engine were removed for use in other prototypes.
Hoffmann carried out two altitude flights in the Fl 282 V3 on April 27, 1942. On the first he reached a height of 3,500 meters over the takeoff point and on the second (from 1517 to 1610 hours) 3,800 meters in 36 minutes.
The Fl 282 V5, which featured a number of changes compared to the V3 (tail surfaces, fuselage, pilot seat), began flying in January 1942. It also remains to be mentioned that the Fl 282 V2 and V3 had a fully-glazed cockpit. From the V5 on the pilot seat was either entirely open or had a plexiglass shield in front or on the sides.
Various empennage arrangements were also tested. The V3 had a horizontal stabilizer right and left with end fins. A V-shaped stabilizer, similar to that of the Cierva C 30, was installed on the V23.
Calculations revealed that reversing the direction of rotation of the rotor should significantly improve directional stability, especially at low power settings. The V8 was rigged up as a test bed to confirm this. Flight tests with the V9 and V15 began in September 1942 and confirmed the theoretical findings. Directional stability was so good, that the entire fuselage section aft of the firewall was simply left off the V9. Flight tests were problem free. The V9 was the prototype for a version to be operated by the Navy from large submarines and designated "Modified Model in Form of a Standing Cylinder" (Fl 282 U).
The Fl 282 V21 and V23 were built as two-seaters; an observer sat with his back to the pilot in the fuselage behind the engine block. This made necessary the removal of the fuselage fuel tank; it was replaced by two unprotected, cylindrical tanks mounted externally on both sides of the pilot seat. Furthermore, a different rotor arrangement - two three-blade rotors - was tried out on the test bed. It proved to run extraordinarily smoothly, however this was not a consideration for military use.
The entire Fl 282 flight test program was not conducted at Rechlin, as was customary for land-based aircraft; instead, from August 1942, trials were carried out at E-Stelle See Travemünde. In charge of helicopter and autogiro testing there was Fliegerstabsingenieur Dipl. Ins. Hans Fischer; his assistant was Fliegerstabsingenieur Dipl. Ing. Otto Dumke. After Fischer was badly hurt in the crash of one of the E-Stelle’s Do-217’s, Fliegerstabsingenieur Dipl.lng. Gerhard Geike assumed responsibility for the workings of this group.
Travemünde was selected because the air traffic safety ship Greif was based there and could be used for deck landing trials. The site also simplified helicopter sea trials with the navy, it was also imperative to move the site of the trials from Flettner's facility in Berlin, where there was a greater risk from the growing Allied bombing raids.
One special experiment took place in cooperation with the DVL's Institute for Marine Aviation. It involved "towing tests with a 50kg gliding body." The proposal originated from the director of the Erprobungs- und Lehrkommando (Testing and Instruction Detachment) 20, Hauptmann von Winterfeldt, who carried out the towing flights from an antisubmarine vessel in Gotenhafen on May 3 and 4,1943. In addition to its role as a reconnaissance aircraft in support of the sub-chasers, armed with bombs the Fl 282 was also to participate actively in the anti-submarine role.
The following extract from the E-Stelle Travemunde's monthly report of June 1944 is also worthy of mention:
"A mock combat between the Fl 282 (Flettner company pilot Fuisting) and a Fw 190 (pilot Ltn. Eisenlohr of E.Kdo.25) took place at Schweidnitz on 22.06.1944, in order to investigate the chances of a fighter hitting a helicopter. At present the evaluation of the film and the pilot reports have not yet arrived. At heights above 100 meters the fighter was able to get the helicopter in its sights briefly. Near the ground, especially in difficult terrain, the fighter has little chance against a helicopter."
Vulnerability to gunfire was also investigated, whereby they proceeded on the assumption that the mathematical probability of a moving rotor blade being hit was much less than that of a fixed wing. Another consideration was that it should be extremely difficult to fire on and hit the slow-moving helicopter from a fast fighter. The latter could escape by making brief evasive movements, which the fighter could not follow. Furthermore, tests involving ground firing at the moving rotor blades were carried out, as the helicopter was felt to be more vulnerable to gunfire from the ground than from the air. An unmanned, tethered Kolibri was used; in spite of several hits in the rotor blades ground fire failed to bring down the helicopter.
The "Anton Flettner G.m.b.H." was a small engineering company dedicated to helicopters. It is believed that the firm was founded in Berlin in 1935. The earliest document the author has been able to find is a letter from the Military Economics inspectorate (W.I.) III, Berlin to the RLM concerning firms involved in production for the Luftwaffe and dated October 2, 1936. The letter states that the W.I. III first became aware that the firm had been given important work by the RLM (LC II) as the result of a formal application for an exemption from military service for one of Flettner’s skilled workers.
The same inspectorate sent the secrecy agreements to the Flettner Company, Berlin-Johannisthal, Segelfliegerdamm 27, for signature on January 22, 1937.
Due to the growing number of air raids on Berlin, in August 1943 the company began transferring its operations to Schweidnitz in Silesia (approx. 50 km SW of Breslau); due to the deterioration of the transportation system the operation took several months. The Fl 282s on hand with the company were also flown to Schweidnitz to continue the test program. In February 1944 the workforce reached approximately 120 men, its highest level ever.
With the Red Army approaching Silesia, in January/February 1945 the company moved back to Berlin-Tempelhof. Any systematic work or further production was of course out of the question under these circumstances. To make matters worse, two days after its arrival the rest of the company's equipment was destroyed in a night raid on Tempelhof. What was left of Flettner was subsequently evacuated to Bad Tolz (Upper Bavaria); two Fl 282s were also flown there. The history of the Anton Flettner G.m.b.H. ended there with the arrival of American troops.
Technical description of the Fl 282 B-0 and B-1 (as of 23.12.1943)
1. Purpose: I. Reconnaissance aircraft (land); II. Shipboard reconnaissance aircraft.
2. Designation: Fl 282 B-0 (with no cockpit glazing). Fl 282 B-1 (plexiglass glazed canopy).
3. Crew: one pilot
4. Design: Single-engined helicopter and gyroplane of mixed construction with two rotors.
(a) Fuselage: Welded steel tube, truss-type construction. Forward section with open (B-0) or enclosed (plexiglass] cockpit (B-1). Recess for back-type parachute in rear wall of seat. The fuselage center-section contains the entire power plant, the outer skin consists of removable doors, hoods and panels. Oval cross-section. The rear fuselage is fabric-covered with a rectangular cross-section.
(b) Rotor Blades: A tubular steel spar with riveted-on wooden ribs and plywood skin with fabric covering. Rectangular outline with rounded tips. Attached to rotor head with delta and alpha hinges. Receptacle for balance weight at end of spar (scrap). The axes of both rotors are angled outboard at 12° from the vertical. Seen from above, the right rotor rotates clockwise, the left counterclockwise.
(c) Control Surfaces: No elevator. Two-part horizontal stabilizer with single spar. Tubular steel spar with riveted-on wooden ribs. Plywood leading edge, fabric-covering, cantilever construction. Angle of incidence adjustable between -15 and +5° from cockpit.Rudder: wooden construction, fabric-covered, deflection to 40°. Vertical stabilizer: wooden construction with plywood leading edge and fabric covering, bolted to fuselage frame. No ailerons.
(d) Undercarriage: Braced fixed nosewheel with VDM oil shock-absorber leg, coupled with rudder foot pedals (steerable nosewheel). Nosewheel: EC tire 350 x 150mm. Mainwheels: EC tires 465 x 165mm.
5. Power Plant
(a) Engine Type: 1 BMW 314 E. Output: 160hp, compression ratio 1:6.0, rotor reduction ratio: 1:12.
(b) Transmission: Lower transmission flange-mounted on front of engine, in front cooling fan on extended crankshaft. Upper transmission, linked to the lower by a double cardan shaft. Firewall over and behind the engine.
(c) Fuel Tank: An unprotected metal tank located behind the firewall in the aft fuselage, consumable content 105 liters.
(d) Oil Tank: An unprotected 10-liter metal tank flange-mounted on the lower gearbox. Oil content of upper gearbox = 5l.
(e) Type of Fuel: 87 octane aviation gasoline.
(f) Cooling System: Continuous cooling provided by an eight-blade wooden cooling fan with direct drive from the engine. Oil cooler which is switched off for cold-weather operalion.
(g) Control System: Control about all three axes by means of periodic or constant changes in angle of incidence of the rotor blades by means of stick and rudder pedals, to which the rudder is connected. Change-over from helicopter to autogiro (autorotation) flight and reverse achieved by means of a speed-sensitive hydraulic regulator controlled by a hand-operated control lever; change-over to autorotation mode is automatic in the event of engine failure.
(a) Flight Instruments and Navigation Equipment: 1 airspeed indicator, 1 altimeter, 1 vertical speed indicator, 1 turn-and-bank indicator, 1 RPM indicator for rotors, 1 rotor blade angle indicator, 1 master compass, 1 dash-board clock.
(b) Safety and Rescue Equipment: 1 back-type parachute, 1 first-aid kit, 1 one-man inflatable raft (shipboard reconnaissance version).
(c) Radio and Signalling Equipment: 1 FuG 19 radio installation, 1 rigidly-mounted single-barrel flare pistol, 1 rigidly-mounted signal lamp (shipboard reconnaissance version).
(d) Bomb-Release Mechanism: 1 bomb magazine for two 5kg explosive devices (ship board reconnaissance version). 1 magazine for smoke buoys (shipboard reconnaissance version).
8. Special Equipment: Deck-landing equipment, consisting of: 1 tether with landing cable and electrical release.
9. Dimensions: Length of aircraft: 6150mm. Width, including undercarriage and tail surfaces: 2400mm. Height with rotor blades removed: 2400mm. Rotor diameter: 12000mm.
10. Technical Data: (a) construction group: H 3; (b) maximum allowable flying weight: 1.000kg; (c) wing loading: 8.84 kg/m2 (based on rotor surface area); (d) maximum allowable speeds: as helicopter: forward: 80 km/h, backward: 30km/h, sideways: 20km/h; as autogiro: 60km/h; (e) minimum allowable speeds: as helicopter: no limitations; as autogiro: 40km/h, aerobatic forbidden!
11. Performance: (a) Speed: Speed is temporarily limited to 80km/h in horizontal flight in helicopter mode for reasons of structural strength, 60km/h in autogiro mode.
(b) Rate of climb: 4.5m/s at sea level, 3.5m/s at 1000m, 3.0m/s at 1500m. Maximum altitude temporarily restricted to 1500 meters for flight safety reasons.
(c) Takeoff and Landing Performance: Takeoff and landing are made vertically. Autorotation landing in event of engine failure. Landing distance from height of 20m: 50m, stopping distance 15m (with wind speed of 5m/s).
12. Range: Endurance of 2 hours 5 minutes at maximum allowable speed of 80km/h and a range of 168km. The "Technical Description Fl 282 B-0 and B-1" presented above was prepared with the Fl 282 V12.
"The Luftwaffe Profile Series No.6 - Flettner Fl 282", 1996
Flettner's improved helicopter was the two-seat Fl 282 Kolibri (Hummingbird), and to speed the development of an aircraft that could prove valuable for naval use, a total of 30 prototypes and 15 pre-production examples were ordered in early 1940. Although the basic fuselage configuration was similar to that of its predecessor, the Fl 282 differed in one important respect. Its Bramo Sh 14A engine was mounted in the centre fuselage and the pilot was accommodated in the nose with enclosed, semi-enclosed and open cockpits provided in variety over the 24 prototypes that were built. Not all of these were two-seaters, but those that were accommodated an observer in a position aft of the main rotor pylon, seated so that his view was to the rear of the aircraft.
In 1942 the German navy began its trials of the Fl 282, finding the type extremely manoeuvrable, stable in poor weather conditions, and so reliable that in 1943 about 20 of the 24 prototypes were operating from warships in the Aegean and Mediterranean for convoy protection duties. It was discovered that as pilots gained experience the Fl 282s could be flown in really bad weather, leading to an order for 1,000 production aircraft. These were not built as a result of Allied bombing attacks on the BMW and Flettner works, and only three of the prototypes survived at VE-Day, the remainder being destroyed to prevent them being captured.
D.Donald "The Complete Encyclopedia of World Aircraft", 1997
* * *
- Only 24 of the 30 prototypes and 15 pre-production aircraft were completed before the end of the war.
- One Fl 282 accumulated 95 flying hours without any repairs.
- Pulling back violently on the controls could cause the rotors to strike the fin.
- One aircraft is retained at the Midland Air Museum in Coventry and another at the US Air Force Museum, Ohio.
- Using his Fl 282 experience, Flettner began designing the 20-passenger Fl 339.
- Hans E. Fuisting performed most of the Fl 282 test-flying.