Doblhoff WNF 342

     
Název:
Name:
Doblhoff WNF 342 V4 Doblhoff WNF 342 V4
Originální název:
Original Name:
Doblhoff WNF 342 V4
Kategorie:
Category:
experimentální vrtulník experimental helicopter
Výrobce:
Producer:
DD.MM.1943-DD.MM.1943 Wiener Neustädter Flugzeugwerke GmbH, Wiener Neustadt /
DD.MM.1944-DD.MM.1945 Wiener Neustädter Flugzeugwerke GmbH, Ober-Grafendorf /
Období výroby:
Production Period:
DD.MM.1943-DD.MM.1945
Vyrobeno kusů:
Number of Produced:
4(?)
První vzlet:
Maiden Flight:
DD.MM.RRRR
Osádka:
Crew:
1 (V1/V3)
2 (V4)
Základní charakteristika:
Basic Characteristics:
 
Uspořádání rotorů:
Rotor Configuration:
rotor bez reakčního momentu no torque rotor
Podvozek:
Undercarriage:
pevný fixed
Přistávací zařízení:
Landing Gear:
kola wheels
Technické údaje:
Technical Data:
 
Hmotnost prázdného vrtulníku:
Empty Weight:
430 kg 948 lb
Vzletová hmotnost:
Take-off Weight:
640 kg 1411 lb
Maximální vzletová hmotnost:
Maximum Take-off Weight:
675 kg 1488 lb
Délka s otáčejícími se rotory:
Length with Rotors Turning:
9,96 m 32ft 8,12in
Délka trupu:
Fuselage Length:
6,07 m 19ft 10,97in
Šířka trupu:
Fuselage Width:
2.51 m 8ft 2,81in
Celková výška:
Overall Height:
2.76 m 9ft 0,65in
Průměr hlavního rotoru:
Main Rotor Diameter:
9,96 m 32ft 8,12in
Průměr vyrovnávacího rotoru:
Tail Rotor Diameter:
- m -
Plocha disku hlavního rotoru:
Main Rotor Disc Area:
77,91 m2 838.62 ft2
Plocha disku vyrovnávacího rotoru:
Tail Rotor Disc Area:
- m2 - ft2
Pohon:
Propulsion:
 
Kategorie:
Category:
pístový piston
Počet motorů:
Number of engines:
1
Typ:
Type:
turbokompresor z motoru As 411 poháněný motorem:
V1: Walter Mikron II o výkonu 44,1 kW/60 k
V2: Walter Minor 4-II o výkonu 62,5 kW/85 k (nebo Hirth HM 504, 77,2 kW/105 k)
V3/4: Argus As 8 B o výkonu 99 kW/135 k (nebo Bramo 314 A, 103 kW/140 k)
As 411 compressor powered by:
V1: Walter Mikron II, power 59.2 hp
V2: Walter Minor 4-II, power 83.8 hp(or Hirth HM 504, power 103.5 hp)
V3/4: Argus As 8 B, power 133 hp (or Bramo 314 A, power 138 hp)
Objem palivových nádrží:
Fuel Tank Capacity:
? ?
Výkony:
Performance:
 
Maximální rychlost:
Maximum Speed:
? km/h v ? m ? mph in ? ft
Cestovní rychlost:
Cruise Speed:
40 km/h v 0 m 24.9 mph in 0 ft
Rychlost stoupání:
Climb Rate:
? m/s ? ft/min
Statický dostup:
Static Ceiling:
? m ? ft
Dynamický dostup:
Dynamic Ceiling:
? m ? ft
Dolet:
Range:
? km ? mi
Maximální dolet:
Maximum Range:
? km ? mi
Přepravní kapacita:
Transport Capacity:
- -
Výzbroj a vybavení:
Armament and Equipment:
 
Výzbroj:
Armament:
- -
Vybavení:
Equipment:
- -
Uživatelské státy:
User States:
- -
Poznámka:
Note:
- -
Zdroje:
Sources:
Nowarra, Heinz J. Die deutsche Luftrüstung 1933-1945, Band 1: Flugzeugtypen AEG-Dornier. Bernard & Graefe Verlag, Koblenz 1993. ISBN 3-7637-5465-2.
Nowarra, Heinz J. German Helicopters 1928-1945. Schiffer Publishing, West Chester 1990. ISBN 0-88740-289-5.
Witkowski, Ryszard. Rotorcraft of the Third Reich. Stratus, Sandomierz 2007. ISBN 978-83-89450-43-2.
Griehl, Manfred, Dressel, Joachim. Deutsche Hubschrauber for 1945. Waffen-Arsenal band 128. Podzun-Pallas Verlag, Friedberg 1993. ISBN 3-7909-0418-X.
www.luftarchiv.de
www.aviastar.org
URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#209118 Version : 0

Doblhoff WNF 342 - the first jet helicopter


In 1939, a single gentleman named Friedrich von Doblhoff, a 24-year-old recent graduate of Vienna engineering, presented his plans for a helicopter powered by jets on the ends of the rotor blades to the engineers of Wiener Neustäter Flugzeugwerke. This arrangement would have greatly simplified the propulsion system, eliminated the need for rotor reaction torque compensation, and resulted in an overall weight saving of up to 20% at the cost of less efficiency. Doblhoff did not find support within the company, but nevertheless embarked on experiments with his colleagues Theodor Laufer and August Stefan. Together, in 1942, they built a simple test rig with a three-bladed rotor into whose blades a mixture of air and petrol was blown through hollow beams. At the ends of the blades were simple combustion chambers where automobile candles ignited the mixture. The test bed worked so well, according to Kenneth Munson, that the frame came loose from its mounts and lifted the anvil, which served as ballast, about a foot into the air. However, the structure did not survive the "landing".


It was probably only after this that the Reich Aviation Authority became aware of this small "research group" and ordered the work to stop. However, Doblhof not only managed to persuade the officials to reverse the decision, but also won an official contract to build a prototype jet helicopter, officially designated WNF 342. Doblhoff hoped that his helicopter would succeed in the Navy's competition for an observation helicopter for submarine service, and according to some sources, the Navy financially supported the development of the WNF 342.


So in 1942, Doblhoff, Laufer, Stefan and about 20 of their associates began work on the first prototype. This machine had a simple frame design, a nose gear and twin tail surfaces, which were modified many times during the development. For propulsion, a Walter Mikron II engine was used to drive a compressor taken from the As 411 engine. This then served as a source of pressurised air. Initially, fuel injection was tested under pressure, but later it was switched to heating the fuel in an exhaust gas heated heat exchanger to 160 °C and mixing it with air before the compressor. The 1:20 air/gasoline mixture at temperatures slightly above 2000 °C was then burned in chambers of chromoly steel at the end of each rotor blade. The blades themselves had a hollow duralumin beam with a wooden trailing edge and a bakelite resin filling. The control of the blades was ultimately chosen to be cyclic. In the spring of 1943, WNF 342 V1, piloted by Auguste Stefan, was to make its first tethered takeoff inside the hangar. The machine was also to be presented to Göring, who visited the factory on 7 May 1943. Manfred Griehl and some other authors, however, give a different timeline, according to which the first tethered take-off did not take place until September 1943 and then a free flight on 2 October, during which (or perhaps already during the tethered take-off) the helicopter was to reach a height of eight metres and stay in the air for eight minutes. In any case, the performance of the helicopter was quite satisfactory, only the considerable thirstiness of this arrangement was criticized, and the need for greater longitudinal stability was also mentioned.


Between 12 April and 29 May 1944, five raids were undertaken which severely damaged the parent plant in Vienna New Town. As a result, WNF 342 V1 was also damaged or perhaps destroyed, and further work was moved to the branch plant at Ober-Grafendorf. (According to the "spring" timeline, the move was the result of the 13 August 1943 raid.) Here a second prototype was built, which was essentially identical to the first (it is sometimes even suggested that it was built by rebuilding it, or at least using its parts), but had a new dimensional tailplane pivoting along the horizontal axis and a more powerful engine. As nothing is ever simple with this helicopter, sources differ as to whether it was a Walter Minor, a Hirsch HM 504, a sort of "Walter Mikron 4-II" or simply an anonymous 90hp engine.


The V2 was also flown by Auguste Stefan, but was found to lag behind the old number one in performance, perhaps due to the increase in overall weight from 360 to 460 kg. The third prototype therefore took a different form. The problem of high fuel consumption was to be solved by using jets only for take-off and landing, for forward flight the rotor was to be set to autorotation and the helicopter was changed to a vortex. Therefore, the V3 received twin tail surfaces mounted on the spars and the Argus As 8 B (or perhaps Bramo Sh 14 A - however, neither the V3 nor the V4 appear to be powered by a radial engine in the photos) engine powered the pusher propeller in addition to the compressor. The rotor now had a diameter of 9.75 m instead of the original 9 m. The small tail-flow propellers were also supposed to be on the previous prototypes, but they are not discernible in the photos. The fuselage was also bonneted for the first time. The theoretically much improved V3 crashed on its first flight, but Stefan escaped unharmed.


The fourth prototype, perhaps a rebuild of the old triple, underwent further tail surface modifications, now with a single rudder located in the middle of the horizontal surface, the rotor blades given a balance to reduce the vibration that destroyed the V3, and full cyclic control. Kurt Hohenemser, an associate of Dr. Flettner, helped with these modifications. The V4 was flown in March 1945 and the modifications proved very successful. The machine flew well and smoothly, staying in the air for 24 hours in tests, but was never tested at speeds above 40 km/h. Soviet troops approached Vienna and thus Ober-Grafendorf, and Doblhoff and his colleagues and the two operational prototypes moved to Zell am See in the foothills of the Kitzbühel Alps, where they surrendered to the Americans on 19 April. Together with them, Doblhoff and the V4 made it to the US, where he later participated in the development of the McDonnell XV-1 convertible. Theodor Laufer worked for the French company SNCASO, where he helped bring to the world the Ariel and Djinn helicopters, which had a rotor powered by compressed air jets, and the Djinn was the first (jet" helicopter to go into series production. August Stefan, the third of the WNF 342's designers, had a career in the UK and worked on the Fairey Gyrodyne helicopter. It is usually reported that the WNF 342 V4 ended up in the collections of the Smithsonian Institution after American trials, but this is probably a mistake.


Nowarra, Heinz J. Die deutsche Luftrüstung 1933-1945, Band 1: Flugzeugtypen AEG-Dornier. Bernard & Graefe Verlag, Koblenz 1993. ISBN 3-7637-5465-2.
Nowarra, Heinz J. German Helicopters 1928-1945. Schiffer Publishing, West Chester 1990. ISBN 0-88740-289-5.
Witkowski, Ryszard. Rotorcraft of the Third Reich. Stratus, Sandomierz 2007. ISBN 978-83-89450-43-2.
Griehl, Manfred, Dressel, Joachim. Deutsche Hubschrauber for 1945. Waffen-Arsenal band 128. Podzun-Pallas Verlag, Friedberg 1993. ISBN 3-7909-0418-X.
Munson, Kenneth. Helicopters and other Rotorcraft since 1907. Blandford Press, London 1973. ISBN 0-7137-06104.
www.luftarchiv.de
www.aviastar.org
URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#607732 Version : 0
http://www.airwar.ru/enc/oh/wnf342.html
www.aviastar.org
.
Doblhoff WNF 342 - WNF 342 V4

WNF 342 V4
Doblhoff WNF 342 -


Doblhoff WNF 342 -


URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#607733 Version : 0
http://www.airwar.ru/enc/oh/wnf342.html
www.aviastar.org

Doblhoff WNF 342 - WNF 342 V1. Klobouk naznačuje, že Stefan vyznával Sikorského teorii ochranných oděvů.

WNF 342 V1. Klobouk naznačuje, že Stefan vyznával Sikorského teorii ochranných oděvů.
Doblhoff WNF 342 - Pozdější podoba.

Pozdější podoba.
Doblhoff WNF 342 -


Doblhoff WNF 342 - Zkušební stolice, kterou vše začalo.

Zkušební stolice, kterou vše začalo.
URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#607737 Version : 0
www.aviastar.org
www.aviastar.org
.
Doblhoff WNF 342 - WNF 342 V2. A klobouk.

WNF 342 V2. A klobouk.
Doblhoff WNF 342 - WNF 342 V3.

WNF 342 V3.
URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#607742 Version : 0
aviacia-all.ru

Doblhoff WNF 342 - Opět WNF 342 V4.

Opět WNF 342 V4.
Doblhoff WNF 342 -


URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#607744 Version : 0
Von Doblhoff and his machine arrived in the US aboard HMS Reaper as part of Operation Lusty. First traveling to the USAAF test facility at Wright Field, the V4 was loaned to General Electric in September 1946 to power the Hughes XR-17 helicopter, later known as the XH-17. One of the principal authors of the resulting report was American pioneer Igor Bensen, who made many takeoffs on WNF 342 and for whom the machine also nearly proved fatal. The crash that essentially destroyed it caused Bensen a spinal injury that tormented him for the rest of his life. Bensen and von Doblhoff then collaborated on the aforementioned XH-17, which also used pressurized air thrusters, but was a huge helicopter for its time, powered by modified J35 jet engines.


The American tests have both solved the mystery of which engine powered the fourth prototype (Argus) and given us a few glimpses of the details of the machine.


retromechanix.com

Doblhoff WNF 342 - Zpráva o testech WNF 342 V4.

Zpráva o testech WNF 342 V4.
Doblhoff WNF 342 -


Doblhoff WNF 342 - Von Doblhoff a jeho kolegové ještě v Zell am See.

Von Doblhoff a jeho kolegové ještě v Zell am See.
Doblhoff WNF 342 - Kokpit.

Kokpit.
Doblhoff WNF 342 - Spalovací komora s tryskou.

Spalovací komora s tryskou.
URL : https://www.valka.cz/Doblhoff-WNF-342-t57857#607750 Version : 0
Discussion post Fact post
Attachments


Join us

We believe that there are people with different interests and experiences who could contribute their knowledge and ideas. If you love military history and have experience in historical research, writing articles, editing text, moderating, creating images, graphics or videos, or simply have a desire to contribute to our unique system, you can join us and help us create content that will be interesting and beneficial to other readers.

Find out more