Praga E-55
{{Short description|1949 Czechoslovak prototype aircraft}}
| {{Infobox aircraft begin
| name=Praga E-55 | image=File:Praga E-55-5.jpg | caption= }}{{Infobox aircraft type | type=Military observation/liaison aircraft | national origin=Czechoslovakia | manufacturer=ČKD-Praga | designer= | first flight=1949 | introduced= | retired= | status= | primary user= | more users= | produced= | number built=1 | program cost= | unit cost= | developed from= | variants with their own articles= }} |
The Praga E-55 was a prototype Czechoslovak multi-purpose single-engine light aircraft designed by ČKD-Praga and intended for the Czechoslovak Army. A single example was built, first flying in 1949, but the type was not selected for production, and the single example was used by an aeroclub before being withdrawn from use in 1953.
Design and development
In November 1947, the Czechoslovak Ministry of Defence issued requirements for two light aircraft for service in support of the Czechoslovak Army, a smaller two-seat aircraft, to be powered by the {{convert|105|hp|kW|abbr=on|order=flip}} Walter Minor 4-III engine and a larger three-seat aircraft to be powered by the {{convert|160|hp|kW|abbr=on|order=flip}} Walter Minor 6-III engine.{{sfn|Marjánek|1976|p=867}}{{sfn|Marjánek|1980|p=712}} The larger aircraft was required to fulfil a number of roles, including observation and liaison duties, casualty evacuation and glider towing. It was required to give a good view in all directions for the observation role, and to operate out of short airstrips and to be easy to maintain in the field. It also needed to be transportable by towing behind a motor car or on the back of a 2.5 tonne{{what|date=January 2025}} truck.{{sfn|Marjánek|1976|pp=867–868}}
In the summer of 1948, the proposal from ČKD-Praga, the E-55, produced by chief designer {{ill|Jaroslav Šlechta|cs}}, was selected to meet the larger, Walter Minor 6, powered requirement, while Aero's Ae 50 was chosen for the smaller Walter Minor-4 powered requirement.{{sfn|Marjánek|1976|p=867}}
The E-55 was a high-winged tractor configuration monoplane, with a pod and boom arrangement. It had a short, heavily glazed fuselage nacelle, with the twin tail carried on the end of a tubular tailboom.{{sfn|Marjánek|1976|p=868}}{{sfn|Bridgman|1956|p=121}} The pilot and an observer sat side-by-side at the front of the enclosed cabin, with a seat for a third crewmember behind them.{{sfn|Bridgman|1956|p=121}} The right front seat could be removed to accommodate racks that could carry two stretchers one above the other, while a medical attendant could sit to the left of the stretchers, although this required operating at overload weights. For glider towing, the aircraft was operated as a single seater, with the radio removed to reduce weight.{{sfn|Marjánek|1976|p=868}} The fabric-covered metal wings were fitted with full-span leading-edge slots and flaps, which could be linked to the ailerons during landing. The aircraft had a fixed tricycle undercarriage.{{sfn|Marjánek|1976|p=868}}{{sfn|Bridgman|1956|p=121}}
The prototype was first flown in autumn 1949, and proved to be badly overweight and underpowered. It was unable to meet the demanding take-off and landing distance requirements of the specification, with take-off run exceeding the specified distance by 93% while the landing distance was 45% longer than required. Tests showed that the aircraft had a dangerous habit of losing height when flaps were retracted after take-off, while ground handling was also poor.{{sfn|Marjánek|1976|pp=867–868}} In June 1950, the Czechoslovak government decided to abandon its observation aircraft programmes, with both the Praga E-55 and the Aero Ae 50 proving disappointing, with the Czechoslovak aircraft industry being directed to concentrate on license-production of Soviet combat aircraft.{{sfn|Marjánek|1976|p=868}}{{sfn|Marjánek|1980|p=713}} Limited development of the E-55 continued, with fitting a {{convert|215|hp|kW|abbr=on|order=flip}} M-8 engine, but this engine never became available.{{sfn|Marjánek|1976|p=868}} Also in 1951, Praga proposed a crop-spraying version, the E-55-H, which would be fitted with a tank for {{convert|250|kg|lb|abbr=on}} of chemicals, but this remained unbuilt.{{sfn|Marjánek|1976|p=868}}{{sfn|Mau|1979|pp=126–127}}
In late 1952, the E-55 was transferred to Svazarm, the Czechoslovak paramilitary youth training organisation, where it was used for parachute training and glider towing.{{sfn|Marjánek|1976|pp=867–868}} It was badly damaged in a landing accident at Mladá Boleslav on 29 June 1953, and was not repaired, and was scrapped, with its wing being used as a training aid at the Brno military academy, while its engine was used in the prototype Zlín Z-226.{{sfn|Marjánek|1976|p=868}}
Operators
; {{CZS}}
Specifications
{{Aircraft specs
|ref=Mongrafie: Praga E-55{{sfn|Marjánek|1976|pp=868–869}}
|prime units?=met
|genhide=
|crew=3
|capacity=
|length m=8.13
|length ft=
|length in=
|length note=
|span m=11.50
|span ft=
|span in=
|span note=
|height m=2.28
|height ft=
|height in=
|height note=
|wing area sqm=17.62
|wing area sqft=
|wing area note=
|aspect ratio=7.5:1{{sfn|Bridgman|1956|p=121}}
|airfoil=NACA 23012
|empty weight kg=723
|empty weight lb=
|empty weight note=
|gross weight kg=1040
|gross weight lb=
|gross weight note=
|max takeoff weight kg=1207
|max takeoff weight lb=
|max takeoff weight note=(overload weight as ambulance){{sfn|Marjánek|1976|p=867}}
|fuel capacity=
|lift kg=
|lift lb=
|lift note=
|more general=
|eng1 number=1
|eng1 name=Walter Minor 6-III
|eng1 type=6-cylinder air-cooled in-line piston engine
|eng1 kw=118
|eng1 hp=
|eng1 shp=
|eng1 note=
|power original=
|prop blade number=2
|prop name=Aero LC 70
|prop dia m=1.95
|prop dia ft=
|prop dia in=
|prop dia note=wooden fixed-pitch propeller
|perfhide=
|max speed kmh=167
|max speed mph=
|max speed kts=
|max speed note=(TAS)
|max speed mach=
|cruise speed kmh=150
|cruise speed mph=
|cruise speed kts=
|cruise speed note=(EAS)
|stall speed kmh=70
|stall speed mph=
|stall speed kts=
|stall speed note=(TAS)
|never exceed speed kmh=
|never exceed speed mph=
|never exceed speed kts=
|never exceed speed note=
|minimum control speed kmh=
|minimum control speed mph=
|minimum control speed kts=
|minimum control speed note=
|range km=450
|range miles=
|range nmi=
|range note=
|combat range km=
|combat range miles=
|combat range nmi=
|combat range note=
|ferry range km=
|ferry range miles=
|ferry range nmi=
|ferry range note=
|endurance=
|ceiling m=3250
|ceiling ft=
|ceiling note=
|g limits=
|roll rate=
|glide ratio=
|climb rate ms=
|climb rate ftmin=
|climb rate note=
|time to altitude=8 min 30 s to {{convert|1000|m|ft|abbr=on}}
|more performance=* Take-off run to 15 m (50 ft): {{convert|410|m|ft|abbr=on}}
- Landing run from 15 m (50 ft): {{convert|250|m|ft|abbr=on}}
|avionics=
}}
See also
References
=Citations=
{{reflist|30em}}
=Bibliography=
- {{cite book |last=Bridgman |first=Leonard |title=Jane's All the World's Aircraft 1956 |year=1956 |location=New York |publisher=The McGraw-Hill Book Company Inc. }}
- {{cite magazine |last=Marjánek |first=Pavel |title=Mongrafie: Aero Ae-50 |magazine=Letectví + Kosmonautika |year=1980 |volume=56 |issue=18 |pages=712–714 |language=cs}}
- {{cite magazine |last=Marjánek |first=Pavel |title=Mongrafie: Praga E-55 |magazine=Letectví a Kosmonautika |year=1976 |volume=52 |issue=22 |pages=867–870 |language=cs}}
- {{cite book |last=Mau |first=Hans Joachim |title=Tschechoslowakische Flugzeuge |year=1979 |location=Belin |publisher=Transpress |isbn=3-344-00121-3 |language=de}}
- {{cite magazine |title=Praga E-55 (ČSR) |magazine=Flieger Revue |year=1979 |issue=1 |page=40 |language=de}}
{{Praga aircraft}}
Category:1940s Czechoslovak military reconnaissance aircraft
Category:Aircraft first flown in 1949
Category:Single-engined tractor aircraft
Category:Aircraft with fixed tricycle landing gear