Raab-Katzenstein RK.25
Raab-Katzenstein RK.25 | |
---|---|
The first RK.25, factory fresh | |
Role | Sport and trainer aircraft
|
National origin | Germany |
Manufacturer | Raab-Katzenstein Flugwerk |
Designer | Paul Hall and Richard Bauer |
First flight | 1928-9 |
Number built | 3 |
The Raab-Katzenstein RK.25 was a two-seat,
Design and development
The RK.25 was noted by contemporaries for its speed, aerodynamic cleanness, its use of new light alloys and, with a range of 2,000–2,400 km (1,200–1,500 mi; 1,100–1,300 nmi), its suitability for long distance touring. It was a low wing, cantilever monoplane with an engine choice between a 80 hp (60 kW)
Its wings were
The RK.25's upright Cirrus engine was neatly cowled in weight-saving elektron, following the upper cylinders to minimise their obstruction of the pilot's forward view.[2] The fuselage had a welded steel tube structure with fabric-covered sides and underside and a curved top which continued the narrow upper engine fairing dorsally. There were two open cockpits in tandem, one occupied by the navigator over the rear wing and the other by the pilot, behind the trailing edge.[1]
Its tail was conventional, with wooden structures and tapered, round-tipped surfaces. The
The RK.25 had a traditional fixed undercarriage with a track of 1.40 m (55 in), its mainwheels on a single axle supported by a pair of V-struts from the lower fuselage.[1] The tops of the forward V-strut members were joined transversely by a beam, free to slide vertically between pairs of fuselage members but restrained by sets of rubber rings which also circled the wing structure as it crossed the fuselage.[2]
The second RK.25 (registered D-1701) was fitted with a Cirrus III engine,[3] the improved cylinder head cooling of which[4] required a slightly wider and raised cowling. It also had raised cockpit sides.[5]
In 1932 the first prototype (D-1489) was rebuilt as the RK.25/32 for the Challenge International de Tourisme 1932. This had an enclosed cabin with large side and upper glazing panels, inboard
Operational history
The date of the RK.25's first flight is not known, though the prototype was registered in September 1928.[8] It and the second example competed in the 1929 Challenge;[9] the latter, with its more powerful engine and flown by John Carberry, came third.[10]
A third and final RK.25 was registered to Luftfahrtverein Ruhrgau (Ruhrgau flying club) of Essen in 1933.[11]
The RK.25/32 took part in the 1932 Challenge, though it was late and only admitted after the payment of a fine.[6] It performed badly in the tests before the tour, coming last of forty-one[12] and engine problems forced it out of the tour at Rimini.[13]
Variants
- RK.25
- Original version with open cockpits and Cirrus II/III engine. Three built.
- RK.25/32
- 1932 version with enclosed cabin and Argus 8 engine. One converted from RK.25.
Specifications RK.25, (Cirrus II)
Data from Les Ailes, February 1929
General characteristics
- Crew: Two
- Length: 6.48 m (21 ft 3 in)
- Wingspan: 9.30 m (30 ft 6 in)
- Height: 2.18 m (7 ft 2 in)
- Wing area: 13 m2 (140 sq ft)
- Empty weight: 295 kg (650 lb)
- Gross weight: 700 kg (1,543 lb)
- Fuel capacity: 300 L (66 imp gal; 79 US gal)
- Powerplant: 1 × Cirrus II 4-cylinder upright air-cooled inline, 60 kW (80 hp) at 2000 rpm
- Propellers: 2-bladed
Performance
- Maximum speed: 200 km/h (120 mph, 110 kn) (185 km/h (115 mph; 100 kn) according to NACA 1930 report[2])
- Cruise speed: 185 km/h (115 mph, 100 kn)
- Range: 2,400 km (1,500 mi, 1,300 nmi)
- Service ceiling: 3,500 m (11,500 ft)
- Time to altitude: 6 min to 1,000 m (3,300 ft)
References
- ^ a b c d e Frachet, André (14 February 1929). "L'avion Raab-Katzenstain R-K 25". Les Ailes (400): 3.
- ^ a b c d e Schrenk, Martin (1930). Aircraft circulars Of the National Advisory Committee for Aeronautics no.579 (PDF). Washington: NACA.
- ^ "Les engagés du Challenge de tourisme International". L'Aérophile. 36 (17–18): 8. 1–15 September 1929.
- ISBN 1 85310294 6.
- ^ Jean-Louis Bléneau. "Raaab Katzenstein R.K.25" (PDF). Richrd Ferriere. Retrieved 30 August 2017.
- ^ a b c "A late entry". Flight. XXI (35): 788. 25 August 1932.
- ^ "Le tour d'Europe et le classement du Challenge international". Les Ailes (585): 8. 1 September 1932.
- ^ "Golden Years of Aviation". Retrieved 31 August 2017.
- ^ "Le Challenge de tourisme sera disputé par avions international". Les Ailes (415): 15. 30 May 1929.
- ^ "The light 'plane tour of Europe". Flight. XXI (47): 1241. 22 November 1929.
- ^ "Golden Years of Aviation". Retrieved 31 August 2017.
- ^ "Les épreuves techniques". Les Ailes (584): 8. 25 August 1932.
- ^ "The International Touring Competition". Flight. XXIV (36): 827. 2 September 1932.