Raab-Katzenstein RK.25: Difference between revisions
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| manufacturer=Raab-Katzenstein Flugwerk |
| manufacturer=Raab-Katzenstein Flugwerk |
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| designer=Paul Hall and Richard Bauer |
| designer=Paul Hall and Richard Bauer |
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| first flight= |
| first flight=1928-9 |
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| introduced= |
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The '''Raab-Katzenstein RK.25''' was a two-seat, [[low wing]] cantilever [[monoplane]] aircraft designed and built in Germany in the 1920s for fast touring. Three were built and one had some success in a 1928 international contest. Another was later re-engined and provided with cabin accommodation. |
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The '''Raab-Katzenstein RK.25''' was a |
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==Design and development== |
==Design and development== |
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The RK.25 noted by contemporaries for its aerodynamic |
The RK.25 was noted by contemporaries for its speed, aerodynamic cleanness, its use of new light alloys and, with a range of {{convert|2000-2400|km|mi nmi|abbr=on}}, its suitability for long distance touring. It was a low wing, cantilever monoplane with an engine choice between a {{convert|80|hp|kW|abbr=on}} [[Cirrus II]] or a {{convert|90|hp|kW|abbr=on}} [[Cirrus III]], both four-cylinder upright air-cooled [[inline engine (aeronautics)|inlines]]. Success in the upcoming first [[Challenge International de Tourisme]] would offer publicity and its points system benefited designs with high performance, high structural strength and low weight.<ref name=Lailes1/> |
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Its wings were [[trapezoidal]] in plan, though with long, rounded tips. Their thickness reduced outwards, largely from below, contributing to the significant [[dihedral (aeronautics)|dihedral]]. Structurally, the wings were wooden, each with two [[longeron]]s which were joined into a box spar by [[plywood]] skin out to three-quarter span; this appears dark in the photograph above. The rest of the surfaces, including the [[balanced rudder|unbalanced]] [[aileron]]s |
Its wings were [[trapezoidal]] in plan, though with long, rounded tips. Their thickness reduced outwards, largely from below, contributing to the significant [[dihedral (aeronautics)|dihedral]]. Structurally, the wings were wooden, each with two [[longeron]]s which were joined into a box spar by [[plywood]] skin out to three-quarter span; this appears dark in the photograph above. The rest of the surfaces, including the [[balanced rudder|unbalanced]] [[aileron]]s which occupied about half the span, were [[aircraft fabric covering|silk covered]].<ref name=Lailes1/> The ailerons had frames of [[Elektron (alloy)|elektron]], a recently developed [[magnesium alloy]].<ref name=NACA/> |
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The RK.25's upright Cirrus engine was neatly [[aircraft fairing#Engine cowling|cowled]] in weight-saving elektron, following the upper cylinders to minimise their obstruction of the pilot's forward view.<ref name=NACA/> 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. There were two open [[cockpit]]s in [[tandem]], one occupied by the navigator over the rear wing and the other by the pilot, behind the [[trailing edge]].<ref name=Lailes1/> |
The RK.25's upright Cirrus engine was neatly [[aircraft fairing#Engine cowling|cowled]] in weight-saving elektron, following the upper cylinders to minimise their obstruction of the pilot's forward view.<ref name=NACA/> 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 [[cockpit]]s in [[tandem]], one occupied by the navigator over the rear wing and the other by the pilot, behind the [[trailing edge]].<ref name=Lailes1/> |
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Its tail was conventional, with tapered, round-tipped surfaces |
Its tail was conventional, with wooden structures and tapered, round-tipped surfaces. The [[elevator (aeronautics)|elevator]]s and the [[leading edge]]s of the [[rudder]] (there was no [[fin (aeronautics)|fin]]) were ply-covered boxes, with silk elsewhere. The tailplane's [[angle of incidence (aerodynamics)|angle of incidence]] could be adjusted on the ground for trimming but its [[elevator (aeronautics)|elevator]]s were unbalanced. A large balanced rudder reached down to the keel and worked in an elevator cut-out.<ref name=Lailes1/><ref name=NACA/> |
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The RK.25 had a traditional fixed [[landing gear|undercarriage]] |
The RK.25 had a traditional fixed [[landing gear|undercarriage]] with a track of {{convert|1.40|m|in|abbr=on}}, its mainwheels on a single axle supported by a pair of V-struts from the lower fuselage.<ref name=Lailes1/> 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.<ref name=NACA/> |
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The second RK.25 was fitted with a Cirrus III engine,<ref name=LaeroP/> the improved cylinder head cooling of which<ref name=Lumsden/> required a slightly wider and raised cowling. It also had raised cockpit sides.<ref name=JLB/> |
The second RK.25 (registered ''D-1701'') was fitted with a Cirrus III engine,<ref name=LaeroP/> the improved cylinder head cooling of which<ref name=Lumsden/> required a slightly wider and raised cowling. It also had raised cockpit sides.<ref name=JLB/> |
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In 1932 |
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 [[Ksoll]] slotted, [[camber (aeronautics)|camber]]-changing [[flap (aeronautics)|flap]]s and independent, [[aircraft fairing|faired]] undercarriage legs.<ref name=Flight2/> It was powered by a {{convert|125|hp|kW|abbr=on|order=flip}} [[Argus As 8]] air-cooled, four cylinder, inverted [[straight engine|inline engine]]<ref name=Lailes3/> and had a maximum speed about {{convert|150|mph|km/h|abbr=on|order=flip}}.<ref name=Flight2/> |
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==Operational history== |
==Operational history== |
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The date of the RK.25's first flight is not known, though the prototype was registered |
The date of the RK.25's first flight is not known, though the prototype was registered in September 1928.<ref name=GY1/> It and the second example competed in the 1929 Challenge;<ref name=Lailes2/> the latter, with its more powerful engine and flown by John Carberry, came third.<ref name=Flight1/> |
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A third and final RK.25 was registered to ''Luftfahrtverein Ruhrgau'' (Ruhrgau flying club) of Essen in 1933.<ref name=GY2/> |
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The RK.25/32 took part in the 1932 Challenge, though it was late and only admitted after the payment of a fine.<ref name=Flight2/> It performed badly in the tests before the tour, coming last of forty-one<ref name=Lailes4/> and engine problems forced it out of the tour at [[Rimini]].<ref name=Flight3/> |
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[[File:Raab_Katzenstein_RK_25-32_L'Aerophile_Salon_1932.jpg|thumb|Raab Katzenstein RK 25/32 photo from L'Aérophile Salon 1932]] |
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[http://gallica.bnf.fr/ark:/12148/bpt6k6554645p/f15 Challenge] |
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[https://www.flightglobal.com/pdfarchive/view/1929/1929-1%20-%200904.html Flight prov results] |
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[http://gallica.bnf.fr/ark:/12148/bpt6k6554634w/f15 3rd in Challenge] |
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[http://gallica.bnf.fr/ark:/12148/bpt6k6554634w/f15 bigger Cirrus] |
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Several refs in Flight 1929-30 |
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[http://richard.ferriere.free.fr/bleneau/raab/raab25.pdf long article] |
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;RK.25: Original version with open cockpits and Cirrus II/III engine. Three built. |
;RK.25: Original version with open cockpits and Cirrus II/III engine. Three built. |
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;RK.25/32: 1932 version with enclosed cabin and Argus 8 engine. One converted from RK.25. |
;RK.25/32: 1932 version with enclosed cabin and Argus 8 engine. One converted from RK.25. |
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==Specifications RK.25, Cirrus II)== |
==Specifications RK.25, (Cirrus II)== |
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[[File:Raab-Katzenstein_RK.25_3-view_Aero_Digest_October_1929.png|thumb|Raab-Katzenstein RK.25 3-view drawing from Aero Digest October 1929]] |
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{{Aircraft specs |
{{Aircraft specs |
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|ref=Les Ailes, February 1929 |
|ref=Les Ailes, February 1929 |
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|max takeoff weight lb= |
|max takeoff weight lb= |
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|max takeoff weight note= |
|max takeoff weight note= |
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|fuel capacity={{convert|300| |
|fuel capacity={{convert|300|L|Impgal USgal|abbr=on}} |
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|more general= |
|more general= |
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<!-- |
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|eng1 number=1 |
|eng1 number=1 |
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|eng1 name=[[ |
|eng1 name=[[Cirrus II]] |
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|eng1 type=4-cylinder upright air-cooled [[straight engine|inline]] |
|eng1 type=4-cylinder upright air-cooled [[straight engine|inline]] |
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|eng1 hp=80 |
|eng1 hp=80 |
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|fuel consumption kg/km= |
|fuel consumption kg/km= |
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|fuel consumption lb/mi= |
|fuel consumption lb/mi= |
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|more performance= |
|more performance= |
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==References== |
==References== |
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{{reflist|refs= |
{{reflist|2|refs= |
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<ref name=Lumsden>{{cite book |title= British Piston Aero-engines and their Aircraft|last=Lumsden|first=Alec| year=1994|pages= |
<ref name=Lumsden>{{cite book |title= British Piston Aero-engines and their Aircraft|last=Lumsden|first=Alec| year=1994|pages=130–1 |publisher=Airlife |location=Shrewsbury |isbn=1 85310294 6 }}</ref> |
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<ref name=NACA>{{cite book |title=Aircraft circulars Of the National Advisory Committee for Aeronautics no.579|first=Martin|last=Schrenk |year=1930 |publisher=NACA |location=Washington |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930094837.pdf}}</ref> |
<ref name=NACA>{{cite book |title=Aircraft circulars Of the National Advisory Committee for Aeronautics no.579|first=Martin|last=Schrenk |year=1930 |publisher=NACA |location=Washington |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930094837.pdf}}</ref> |
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<ref name=Lailes1>{{cite journal |last=Frachet |first=André |date=14 February 1929|title=L'avion Raab-Katzenstain R-K 25|journal=Les Ailes|issue=400 |pages=3|url=http://gallica.bnf.fr/ark:/12148/bpt6k65546307/f3 }}</ref> |
<ref name=Lailes1>{{cite journal |last=Frachet |first=André |date=14 February 1929|title=L'avion Raab-Katzenstain R-K 25|journal=Les Ailes|issue=400 |pages=3|url=http://gallica.bnf.fr/ark:/12148/bpt6k65546307/f3 }}</ref> |
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<ref name= |
<ref name=Lailes2>{{cite journal|date=30 May 1929|title=Le Challenge de tourisme sera disputé par avions international|journal=Les Ailes|issue=415 |pages=15|url=http://gallica.bnf.fr/ark:/12148/bpt6k6554645p/f15}}</ref> |
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<ref name=Lailes3>{{cite journal|date=1 September 1932|title=Le tour d'Europe et le classement du Challenge international|journal=Les Ailes|issue=585 |pages=8|url=http://gallica.bnf.fr/ark:/12148/bpt6k6560181v/f8 }}</ref> |
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<ref name=Lailes4>{{cite journal|date=25 August 1932|title=Les épreuves techniques|journal=Les Ailes|issue=584|pages=8|url=http://gallica.bnf.fr/ark:/12148/bpt6k6560180f/f8}}</ref> |
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<ref name=LaeroP>{{cite journal |date=1–15 September 1929 |title=Les engagés du Challenge de tourisme International |volume=36|journal=L'Aérophile|issue=17-18 |pages=8|url=http://gallica.bnf.fr/ark:/12148/bpt6k6554360b/f269 }}</ref> |
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<ref name=Flight2>{{cite journal |date=25 August 1932 |title=A late entry|journal= [[Flight International|Flight]]|volume=XXI|issue=35 |pages=788 |url= https://www.flightglobal.com/pdfarchive/view/1932/1932%20-%200844.html }}</ref> |
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<ref name=Flight3>{{cite journal |date=2 September 1932 |title=The International Touring Competition|journal= [[Flight International|Flight]]|volume=XXIV |issue=36 |pages=827 |url= https://www.flightglobal.com/pdfarchive/view/1932/1932%20-%200891.html }}</ref> |
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<ref name=JLB>{{cite web |url=http://richard.ferriere.free.fr/bleneau/raab/raab25.pdf|title=Raaab Katzenstein R.K.25 |author=Jean-Louis Bléneau |publisher=Richrd Ferriere |access-date=30 August 2017}}</ref> |
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| ⚫ | |||
<ref name= |
<ref name=GY1>{{cite web |url=http://www.airhistory.org.uk/gy/reg_D-5.html|title=Golden Years of Aviation |access-date=31 August 2017}}</ref> |
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<ref name=GY2>{{cite web |url=http://www.airhistory.org.uk/gy/reg_D-8.html|title=Golden Years of Aviation |access-date=31 August 2017}}</ref> |
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}} |
}} |
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<!-- ==Further reading== --> |
<!-- ==Further reading== --> |
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{{Raab-Katzenstein aircraft}} |
{{Raab-Katzenstein aircraft}} |
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[[ |
[[Category:1920s German sport aircraft]] |
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[[ |
[[Category:Raab-Katzenstein aircraft]] |
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[[Category:Single-engined tractor aircraft]] |
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[[Category:Low-wing aircraft]] |
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[[Category:Aircraft first flown in 1928]] |
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Latest revision as of 18:23, 10 December 2022
| 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, low wing cantilever monoplane aircraft designed and built in Germany in the 1920s for fast touring. Three were built and one had some success in a 1928 international contest. Another was later re-engined and provided with cabin accommodation.
Design and development
[edit]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) Cirrus II or a 90 hp (67 kW) Cirrus III, both four-cylinder upright air-cooled inlines. Success in the upcoming first Challenge International de Tourisme would offer publicity and its points system benefited designs with high performance, high structural strength and low weight.[1]
Its wings were trapezoidal in plan, though with long, rounded tips. Their thickness reduced outwards, largely from below, contributing to the significant dihedral. Structurally, the wings were wooden, each with two longerons which were joined into a box spar by plywood skin out to three-quarter span; this appears dark in the photograph above. The rest of the surfaces, including the unbalanced ailerons which occupied about half the span, were silk covered.[1] The ailerons had frames of elektron, a recently developed magnesium alloy.[2]
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 elevators and the leading edges of the rudder (there was no fin) were ply-covered boxes, with silk elsewhere. The tailplane's angle of incidence could be adjusted on the ground for trimming but its elevators were unbalanced. A large balanced rudder reached down to the keel and worked in an elevator cut-out.[1][2]
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 Ksoll slotted, camber-changing flaps and independent, faired undercarriage legs.[6] It was powered by a 93 kW (125 hp) Argus As 8 air-cooled, four cylinder, inverted inline engine[7] and had a maximum speed about 240 km/h (150 mph).[6]
Operational history
[edit]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
[edit]
- 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)
[edit]
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
[edit]- ^ 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.
- ^ Lumsden, Alec (1994). British Piston Aero-engines and their Aircraft. Shrewsbury: Airlife. pp. 130–1. 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.