Focke Wulf L.G. 61

Focke Wulf L.G. 61
Focke-Wulf Fw-61
number of 2
length 7.29 m
rotor Ø 2 x 7.0 m
height of 2.64 m
crew 1
engine Bramo 314 E
achievement 118 KW (160 HP)
maximum speed 122 km/h
range 230 km
ceiling of 3200 m

the Focke Wulf L.G. 61 (later than Focke Achgelis company 61 designated) was an attempt helicopter, with whose construction Henrich Focke began 1932 and which was built with by it and George the Wulf 1923 created Focke Wulf aircraft construction AG in the years 1935 and 1936 in two copies. They proved fast as the first helicopters in working condition of the world.

Table of contents

the emergence

by the occupation with the autogyros Cierva C.19 and C.30 , as well as with the following, built with Focke Wulf under license, little successful self-development L.G. 186 Henrich Focke had come 1932 to the conclusion that their inadequacies and limited serviceability would be to be eliminated only by a real helicopter. The problems which can be overcome became soon conscious it. There questions of stability were to solve as well as the controllability, above all however had a way to be found to be able to bring with engine breakdown or break of a drive shaft the helicopter surely to soil. Over the characteristics of a rotor both from the inventor of the autogyro, in England working the Spaniard Juan de la Cierva were present, and by work of Glauert and LOCK usable results. First large computations were necessary nevertheless, in order to be able to build models, which could be examined then in the wind tunnel. Focke decided for the arrangement of two rotors,

which would provide moving in opposite directions turning, for symmetry in every respect. A freely flying model propelled by a small two-stroke engine brought promising results to 1934 first success. It is by the way to be seen also today still in the German museum Munich. To 9. February 1935 received from the RLM the order on building of a prototype, which got the designation L.G. 61, to Focke by Focke themselves however in each case F 61 was called. Flat steel bar-mainstaff-sing. Roluf Lucht of the technical office of the RLM was it, which provided for the extension of the order on a second airplane, which to 19. December 1935 happened. The first prototype, the V 1 D-EBVU, Wnr. 931, approximately Dipl. became - engineer this time already finished and Ewald Rohlfs, at the 1. May 1935 as a pilot with Focke Wulf had occurred, began with it the first, still bound test flights in one resounds in Hemelingen, where Focke banished by the determining gentlemen of its own company „“was. The first free flight could do however only to 26. June 1936 take place, because Rohlfs on pressure Udets had to be fetched back only from South America, where rejecting opposite standing management had sent him to the whole project in the spring 1936. Until August were the attempts so far prospered to at the beginning of that the E-place Rechlin could of the Nachfliegen think, with which Dipl. - engineer Ball first EDT was assigned roll ago. This brought certain experiences of flies with one the autogyro C.30 also. Nevertheless the overcautious Focke insisted on letting also it fly first only bound. Ball first EDT was very done by the characteristics of the new equipment, found only the control the height, which took place only via the gas lever operation and thus via change of the rotor speed, somewhat very sensitive. Udet, which had taken over in the meantime the technical office of general William wow, was inspired and pushed to present the helicopter as soon as possible also to the public. In the meantime likewise finished the V 2 D-EKRA, Wnr become. 1789, could start, again with Rohlfs, in the spring 1937 to the first flight. To 10. May 1937 succeeded to it thereby also the first autorotation landing with turned off engine. Later then the world experienced one month with being astonished that Rohlfs with this airplane to 25. and 26. June 1937 all helicopter world records to Germany had gotten. In a time, in which the best performances of other helicopters lay with a flying time of 10 min (D' Ascanio ) or with no more than 1 km air route (Pescara ) and 18 m flight altitude (Oemichen ), the L.G. 61 reached a height of 2439 m, a flying time of 1h 20min 49sec, a speed of 122,553 km/h by means of a distance of 20 km and a air route of 80,604 km in closed course.

Focke induced

a new company the continuous difficulties with its old company to completely separate from it to and, together with the well-known art flier Gerd Achgelis, to 27. To base April 1937 the new company Focke Achgelis & Co GmbH, in which also Weser aircraft construction was involved. The further support of the two helicopters, which were like all new developments realm property, turned into on the new company. Since Rohlfs decided itself to remain with Focke Wulf Focke for the continuation of the attempts set the Dipl. to recommending Udets - engineer Carl Bode . This had belonged as a member of the Akaflieg Hanover to the winner crew of the Germany flight 1933 and changed now, to activities with the E-place Rechlin and with Arado, to Focke Achgelis. The next two pilots, who came to the pleasure to fly the new equipment were Dipl. - engineer Carl Francke of the E-place Rechlin and Hanna Reitsch, the latter actually bad-proves. It would have almost made break for its first flight with this, still, because it had underestimated the difficulty of the helicopter flying nevertheless. One went however well and it soon with the new aircraft trusted. During a flight from Bremen to Tempelhof, which she had to interrupt however on the way first because of to high oil temperature and then again in Stendal because of to unfavorable weather, it could do during the flight from there to Berlin to 25. Octobers 1937 the distance record on straight lines distance equal on 109 km screw. Bode over-bid this value to 20. June 1938 at 230.248 kilometers by a flight from barrel mountain to Berlin rank village again substantially. Finally it placed to 29. January 1939 with the V 2 with 3427 m also Rohlfs old elevator record.

After these successes Udet pushed on immediate admission of series production. The technical designer could convince it however under reference to the single-seatness and thus not given possibility for the briefing by a second pilot as well as to the missing pay load of the fact that first an at least two-seat successor had to be built and tested, before of a quantity production would be to be thought. As result the work on a two-seat successor with the designation company 224 spirit level, which by 280 HP (206 KW, began) a strong Hirth TC 508 or 270 HP (198 KW) a Argus As 10 C engine should be propelled. The draft did not come itself over a mockup out and with outbreak of war completely given up in favor of that likewise already into work companies present 223.

the demonstration in Germany-resounds

Udet was so inspired from the new aircraft that it stated equal another idea. In Germany-resounds in Berlin against year end 1937 a in such a way specified colonial-look with the title Kisuaheli prepared. It interspersed that the new helicopter in for February 1938 the planned revue in the flight should be demonstrated. With the V 2, which had been brought by railway to Berlin, Bode and Hanna Reitsch began to 10. February the preparations, which went first without difficulties over the stage. But to 13. February, in presence of the undersecretary of state milk and Udets, happened it. With Bodes second flight on this day fallow by fatigue the right universal joint, the helicopter tilted to the right, the rotor splintered at the soil and Bode had, fortunately intactly, from which on the back wind lying D-EKRA out. Actually this incident would have been reason of enough, to flies in then the fully occupied resounds its to leave. But all doubts were pushed to the side. Fast the V 1 to Berlin one created and in day and night work for to 19. February taking place premiere fit made, the characteristic D-EBVU at the trunk was removed and replaced by the label Germany. So Hanna Reitsch knew 18mal, which show newest technical achievement in the Fliegerei without further occurrences with the premiere and then from then on daily, altogether. To Udets disappointment was only moderately inspired the public, even if Hanna Reitsch could be pleased personally after stepping out each mark about much applause. The reasons for the dull reaction of the spectators were easy to recognize. Once it was the dust, that the rotors despite previous thorough cleaning of the soil the spectators particularly in the front (expensive) rows into the eyes blew and on the other hand the fact that during the flight demonstration the windows had to be opened and the ventilation on full routes were brought and in February! The reason for it was that Hanna had determined with one of the last test flights that it had to much further put the Gashebel forward, with which the height was steered as normal. One had attributed this obvious power loss of the engine to bad air conditions. The expected enthusiasm of the public was missing thus. Even the technical literature reacted to the alleged sensation quite reservedly. Oskar Ursinus was worth the message in its magazine Flugsport straight 1 ½ to lines. Henrich Focke however received in October 1938 the golden Lilienthal medal and to 12. November of its old technical university Hanover . With now the company 61 being called V 2 were made still attempts into the year 1941, partly with the AVA in Goettingen. It was stored then in ox living with beaver oh, the new seat after the company the Ausbombung in Hoykenkamp and possibly fell with end of war the drawing in Frenchman into the hands. The V 1 however, which was issued at the entrance of Bremen of the work, became with the bomb attack at the night of the 3. on the 4. June [1942] destroys.

afterwards

description for the two helicopters, the L.G. 61 V 1 D-EBVU (Wnr.931) and the L.G. 61 V 2 D-EKRA (Wnr.1789), was taken over the trunk of the simplicity because of of the Focke Wulf L.G. 44 Stieglitz and amended only slightly. It had now only an open operator's seat, kept its normal vertical stabilizer, on which above t-shaped a firm, a abgestrebte, but trimable horizontal stabilizer was put on and got a rigid nose gear wheel chassis, whereby the spur role was maintained. The main wheels were brakable. Two moving in opposite directions turning three-sheet rotors, which were stored on lateral arms welded from steel tube, supplied the lift. They were propelled by a 7-Zylinder Bramo 314 E - radial engine, which was fastened uncovered in the fuselage nose and a small propeller for its own cooling, not however for the production of propulsion had. The largest part of engine performance was transferred over a clutch and a transfer case through in the arm props stored waves and over the Kardangetriebe sitting in the rotor heads to the rotors. Their sheets with doubly trapezoidal sketch and largest depth of profile for instance with a third of the length, consisted of a steel tube as carriers, on the timber ribs with outward removing adjustment angles postponed were for the achievement of necessary cross-setting. A plywood nose resulted in the form of the symmetrical profile in front, while the rear part was covered with material. The sheets were linked with impact and drag hinges at the rotor head. One steered around the roll axis by different adjustment angles at the two rotors. For the forward of or backward motion, in addition, for the turn around the vertical axis the sheets were steered in such a way with each circulation that the inclination of the thrust-resulting at each rotor brought the desired control loads out. The tax inputs were transferred over push pull cables and under the rotor heads attached quadrants to these. A mechanism, which should make a safe landing possible with engine breakdown or drive shaft break, was particularly important. The adjustment angles of all sheets were so far reduced by surrounding a lever that they made an autorotation possible. At the same time the engine was disengaged automatically. A landing in the gliding flight followed. The procedure was however not reversible. After manipulation of the lever had to be landed with autorotation.

Referring to reliable literature:

Steve Coates, Helicopters OF the Third realm, publishing house Ian Allan

Henrich Focke, my life way, report 77-01 the DGLR

Web on the left of

http://www.luftarchiv.de/hubschrauber/fw61.htm
see also: List of the helicopters

 

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