Nagler-Rolz NR 54
{{Short description|German experimental backpack helicopter}}
{{Infobox aircraft
|name= NR 54
|image= NR54.JPG
|image_caption= NR 54 V2 replica at Hubschraubermuseum Bückeburg
|aircraft_type= backpack helicopter
|national_origin= Germany{{cite web |title=Nagler-Rolz NR 54 V2 |url=https://airandspace.si.edu/collection-objects/nagler-rolz-nr-54-v2/nasm_A19590030000 |website=National Air and Space Museum |publisher=Smithsonian Institution |access-date=26 November 2024}}
|manufacturer= Nagler-Rolz Flugzeugbau GmbH
|first_flight=
|introduction= 1940 (NR 55)
1941 (NR 54)
|retired=
|status= Abandoned
|primary_user=
|number_built= 2 (NR 54)
1 (NR 55)
|developed_from=
|variants=
}}
The Nagler-Rolz NR 54 is a German experimental foldable backpack helicopter developed during World War II. An enlarged variant, the NR 55, was also built.
Design and development
The NR 54 was developed by Austrian engineers Bruno Nagler and Franz Rolz. The helicopter featured a three-legged undercarriage design and a single seat. The NR 54 V1 prototype featured a single-bladed rotor, while the V2 prototype had a more traditional two-bladed unit. Both prototypes were powered by a piston engines mounted on the rotor blades, with the V1 having a single {{convert|24|hp|kW|abbr=on}} engine driving two contra-rotating propellers, and the V2 having two {{convert|8|hp|kW|abbr=on}} single-cylinder variants of the Argus As 8. This configuration eliminated torque, negating the need for a tail rotor.{{Cite web|title=Nagler-Rolz NR 54-EN|url=https://www.hubschraubermuseum.de/index.php/en/23-hubschrauber-einrotorig-en/175-nagler-rolz-nr-54-en|access-date=2021-12-11|website=www.hubschraubermuseum.de}}
The enlarged NR 55 a proof of concept aircraft based on the configuration of the NR 54 V1 and was powered by a 40 hp engine in an aerodynamic fairing.
Operational history
The NR 55 was the first airframe built, and conducted a successful hover during indoor testing. Centrifugal forces on the engine caused fuel flow problems, which in turn led to vibration problems, and the propellers created a gyroscopic effect which interfered with the flapping hinges of the rotor. These problems were not fixed on the NR 54 V1 and V2, which were not flown before testing was halted by the Soviet advance in Vienna.
Nagler evaded the Red Army and was interviewed by the British after the war. The NR 54 V1 remained in Austria, while the V2 was captured by American forces after the war, who evaluated it at Freeman Army Airfield. The NR 55 had been destroyed by an Allied bombing raid in 1944.
Variants
;NR 54 V1
:First prototype with a single-bladed rotor.
;NR 54 V2
:Second prototype with a two-bladed rotor.
;NR 55
:Enlarged proof of concept prototype.
Survivors
The NR 54 V2 is currently on display at the Steven F. Udvar-Hazy Center in Chantilly, Virginia.File:Nagler-Rolz NR 54V-2 - NASM Udvar Hazy Center.jpg.]]
Specifications (NR 54 V2)
{{Aircraft specs
|prime units?=met
|genhide=
|crew=1
|capacity=
|length m=2.42
|length ft=7
|length in=11
|length note=
|height m=2.18
|height ft=7
|height in=2
|height note=
|empty weight kg=36.5
|empty weight lb=80
|empty weight note=
|gross weight kg=140
|gross weight lb=309
|gross weight note=
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|max takeoff weight lb=
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|fuel capacity=
|more general=
|eng1 number=2
|eng1 type=single-cylinder two-stroke engine
|eng1 kw=
|eng1 hp=8
|eng1 shp=
|eng1 note=
|power original=
|thrust original=
|prop blade number=2
|prop name=
|prop dia m=0.6
|prop dia ft=1
|prop dia in=11
|prop dia note=
|rot number=1
|rot dia m=8
|rot dia ft=26
|rot dia in=3
|rot area sqm=
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|rot area note=
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See also
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References
{{Commons category}}
{{Reflist}}
{{RLM aircraft designations}}
Category:1940s German experimental aircraft
Category:1940s German helicopters
Category:Twin-engined piston helicopters
Category:Single-engined piston helicopters
Category:Aircraft with fixed conventional landing gear