Praga E-112
| Praga E-112 | |
|---|---|
| |
| Role | Training aircraft |
| National origin | Czechoslovakia |
| Manufacturer | ČKD-Praga |
| First flight | 14 September 1947 |
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
[edit]In 1946, a specification was issued for a two-seat basic training aircraft for use both by the Czechoslovak Air Force and civil users.[1] The new aircraft was required to use a Walter Minor 4-III engine, and was to have a maximum speed of 200 km/h (110 kn; 120 mph), a cruise speed of 180 km/h (97 kn; 110 mph) and to be able to climb to 2,000 m (6,600 ft) in 13 minutes, and have a ceiling of 3,500 m (11,500 ft).[2][3] Two designs competed to meet the specification, one from Zlín (the Zlín Z-26) and one from the ČKD-Praga design team led by Jaroslav Šlechta, the Praga E-112.[1][a]
The Praga design, which was very similar to the competing Zlín,[2] 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.[4] The crew of two sat in tandem under a three-part plexiglass canopy, and were provided with tandem controls.[4]
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.[5] It made its first flight at Letňany on 14 September 1947.[2] A number of modifications were made as a result of factory testing, including revised tail surfaces and a modified engine cowling to improve cooling,[1][2] but a more significant problem was that the aircraft's propeller was unsuitable, so that the engine would not run at the required speed.[6] Both the E-112 and Z-26 were delivered for evaluation in February 1948.[2] The E-112's speed was slightly below the 200 km/h required by the specification,[6] 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),[3] partly due to the poorly matched propeller and failed attempts to modify it to improve the aircraft's speed.[6] As a result, the Z-26 was chosen to meet the requirement and ordered into production.[1] 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.[6]
Specifications
[edit]Data from Monografie: Praga E-112[1]
General characteristics
- Crew: 2
- Length: 7.60 m (24 ft 11 in)
- Wingspan: 10.65 m (34 ft 11 in)
- Height: 2.25 m (7 ft 5 in)
- Wing area: 15.25 m2 (164.1 sq ft)
- Empty weight: 568 kg (1,252 lb)
- Gross weight: 835 kg (1,841 lb)
- Powerplant: 1 × Walter Minor 4-III 4-cylinder air-cooled in-line piston engine, 78 kW (105 hp)
Performance
- Maximum speed: 205 km/h (127 mph, 111 kn)
- Cruise speed: 180 km/h (110 mph, 97 kn)
- Range: 570 km (350 mi, 310 nmi)
- Service ceiling: 3,500 m (11,500 ft)
- Time to altitude: 15 minutes to 2,000 m (6,600 ft)
Notes
[edit]- ^ 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.[1]
References
[edit]
- ^ a b c d e f Němeček 1975, p. 309.
- ^ a b c d e Letectví a Kosmonautica 1976, no. 3, p. 100.
- ^ a b Volejník 1992, p. 1205.
- ^ a b Němeček 1975, pp. 309–310.
- ^ Letectví a Kosmonautica 1976, no. 3, pp. 100–101.
- ^ a b c d Letectví a Kosmonautica 1976, no. 3, p. 101.
- "Jak to Tenkrát Bylo: Aneb Z-26 a E-112 po 28 letech". Letectví a Kosmonautica (in Czech). Vol. LII, no. 3. 1976. pp. 100–101.
- Němeček, Václav (1975). "Monografie: Praga E-112". Letectví a Kosmonautica (in Czech). Vol. LI, no. 8. pp. 309–310.
- Volejník, Jiří (1992). "Se značkou ZLIN…". Letectví a Kosmonautica (in Czech). Vol. LXVIII, no. 19. pp. 1205–1206. ISSN 0024-1156.