Praga E-112
| {{Infobox aircraft begin
| name=Praga E-112 | image=Praga E-112-1.jpg | caption= }}{{Infobox aircraft type | type=Training aircraft | national origin=Czechoslovakia | manufacturer=ČKD-Praga | designer= | first flight=14 September 1947 | introduced= | retired= | status= | primary user= | more users= | produced= | number built= | program cost= | unit cost= | developed from= | variants with their own articles= }} |
The Praga E-112 was a prototype Czechoslovak training aircraft of the 1940s. It was built to meet a requirement for an elementary trainer for both the Czechoslovak Air Force and civil use, first flying in September 1947. After testing, it was rejected in favour of the Zlín Z-26, and no production of the E-112 followed.
Design and development
In 1946, a specification was issued for a two-seat basic training aircraft for use both by the Czechoslovak Air Force and civil users.{{sfn|Němeček |1975|p=309}} The new aircraft was required to use a Walter Minor 4-III engine, and was to have a maximum speed of {{convert|200|km/h|kn mph|abbr=on}}, a cruise speed of {{convert|180|km/h|kn mph|abbr=on}} and to be able to climb to {{convert|2000|m|ft|abbr=on}} in 13 minutes, and have a ceiling of {{convert|3500|m|ft|abbr=on}}.{{sfn|Letectví a Kosmonautica 1976, no. 3|p=100}}{{sfn|Volejník|1992|p=1205}} Two designs competed to meet the specification, one from Zlín (the Zlín Z-26) and one from the ČKD-Praga design team led by {{ill|Jaroslav Šlechta|cs}}, the Praga E-112.{{sfn|Němeček |1975|p=309}}{{#tag:ref|In the 1930s, Šlechta had designed an unbuilt development of the Praga BH-111, also designated E-112, but despite the identical designation, the aircraft proposed for the 1946 specification was a new design.{{sfn|Němeček |1975|p=309}}|group=lower-alpha}}
The Praga design, which was very similar to the competing Zlín,{{sfn|Letectví a Kosmonautica 1976, no. 3|p=100}} was a tractor configuration cantilever monoplane of mixed wood and metal construction with a fixed tailwheel undercarriage. The low-mounted wing was made of wood, while the fuselage had a welded steel-frame structure with fabric covering.{{sfn|Němeček |1975|pp=309–310}} The crew of two sat in tandem under a three-part plexiglass canopy, and were provided with dual controls.{{sfn|Němeček |1975|pp=309–310}}
Construction of the prototype was assigned to Letov at their Letňany, Prague factory, but the quality of construction was poor, with the aircraft overweight and showing a poor surface finish, particularly compared to the Z-26.{{sfn|Letectví a Kosmonautica 1976, no. 3|pp=100–101}} It made its first flight at Letňany on 14 September 1947.{{sfn|Letectví a Kosmonautica 1976, no. 3|p=100}} A number of modifications were made as a result of factory testing, including revised tail surfaces and a modified engine cowling to improve cooling,{{sfn|Němeček |1975|p=309}}{{sfn|Letectví a Kosmonautica 1976, no. 3|p=100}} but a more significant problem was that the aircraft's propeller was unsuitable, so that the engine would not run at the required speed.{{sfn|Letectví a Kosmonautica 1976, no. 3|p=101}} Both the E-112 and Z-26 were delivered for evaluation in February 1948.{{sfn|Letectví a Kosmonautica 1976, no. 3|p=100}} The E-112's speed was slightly below the 200 km/h required by the specification,{{sfn|Letectví a Kosmonautica 1976, no. 3|p=101}} while its climb rate was much poorer than required (it took 18 minutes, 23 s to reach 2000 m compared with the 13 min required by the specification),{{sfn|Volejník|1992|p=1205}} partly due to the poorly matched propeller and failed attempts to modify it to improve the aircraft's speed.{{sfn|Letectví a Kosmonautica 1976, no. 3|p=101}} As a result, the Z-26 was chosen to meet the requirement and ordered into production.{{sfn|Němeček |1975|p=309}} Work continued to improve the E-112 into 1949, and fitting new propellers significantly improved performance, particularly climb rate, but this did not result in any production orders.{{sfn|Letectví a Kosmonautica 1976, no. 3|p=101}}
Specifications
{{Aircraft specs
|ref=Monografie: Praga E-112{{sfn|Němeček |1975|p=309}}
|prime units?=met
|genhide=
|crew=2
|capacity=
|length m=7.60
|length note=
|span m=10.65
|span note=
|height m=2.25
|height note=
|wing area sqm=15.25
|wing area note=
|aspect ratio=
|airfoil=
|empty weight kg=568
|empty weight note=
|gross weight kg=835
|gross weight note=
|max takeoff weight kg=
|max takeoff weight lb=
|max takeoff weight note=
|fuel capacity=
|lift kg=
|lift lb=
|lift note=
|more general=
|eng1 number=1
|eng1 name=Walter Minor 4-III
|eng1 type=4-cylinder air-cooled in-line piston engine
|eng1 kw=
|eng1 hp=105
|prop blade number=
|prop name=
|prop dia m=
|prop dia ft=
|prop dia in=
|prop dia note=
|perfhide=
|max speed kmh=205
|max speed note=
|cruise speed kmh=180
|cruise speed note=
|stall speed kmh=
|stall speed mph=
|stall speed kts=
|stall speed note=
|range km=570
|range note=
|endurance=
|ceiling m=3500
|ceiling note=
|g limits=
|roll rate=
|glide ratio=
|climb rate ms=
|climb rate ftmin=
|climb rate note=
|time to altitude=15 minutes to {{convert|2000|m|ft|abbr=on}}
|more performance=
|avionics=
}}
Notes
{{reflist|group=lower-alpha}}
References
{{Commons category}}
{{reflist}}
- {{cite magazine |title=Jak to Tenkrát Bylo: Aneb Z-26 a E-112 po 28 letech |magazine=Letectví a Kosmonautica |year=1976 |issue=3 |volume=LII |pages=100–101 |language=cs |ref={{harvid|Letectví a Kosmonautica 1976, no. 3}} }}
- {{cite magazine |last=Němeček |first=Václav |title=Monografie: Praga E-112 |magazine=Letectví a Kosmonautica |year=1975 |issue=8 |volume=LI |pages=309–310 |language=cs}}
- {{cite magazine |last=Volejník |first=Jiří |title=Se značkou ZLIN… |magazine=Letectví a Kosmonautica |year=1992 |issue=19 |volume=LXVIII |pages=1205–1206 |language=cs |issn=0024-1156}}
{{Praga aircraft}}
Category:1940s Czechoslovak military trainer aircraft
Category:Aircraft first flown in 1947
Category:Single-engined tractor aircraft