Praga engines were built originally by Ceskomoravska-Kolben-Danek, Ltd. (C-K-D) of Prague, Czechoslovakia. C-K-D was founded in 1927 by a merger of C-K and Breitfeld-Danek (B-D). Ceskomoravska dated from 1914 and began by building V-8 & V-12 aeroengines. B-D began producing aeroengines in 1914 shortly after the beginning of WWI and built rotary engines and later Austro-Hungarian Hiero engines under license. B-D built their own designs from 1923. After the merger, C-K-D held licenses for high-power French Lorraine-Dietrich and Italian Isotta-Fraschini engines. C-K-D built engines for light aircraft beginning in the 1930s. Their products included inline engines as well as the HOAE described below. Jowett Cars Ltd. of Idle, Bradford in the UK obtained a license in 1936 for the Praga B engine. After Nazi Germany took over Czechoslovakia in 1938, the firm was reconstituted as Böhmisch-Maerische Maschinenfabriken, A.G. to be part of WWII German aircraft engine production. Manufacture and development of the pre-war engines resumed after WWII by nationalization as the Czechoslovak Metal Engineering Works, National Corporation, of Prague XVII - Jinonice. Later, in the mid-1950s, all of the Czech aviation industry was grouped into the Ceskolovenske Zavody Automobilove a Letecke (Czechoslovak Automobile and Aircraft Works), also in Prague. This firm introduced, c.1956, another HOAE, the Doris B under the well-respected Praga name, and it was marketed, probably, by Omnipol.
O-116 -- {4.134 / 4.331 / 116.3} / {105 / 110 / 1905}
2cyl; Praga 36, Praga B; 36hp@N/A rpm; 1935-1940; Wt = 106#.
Dual-ignition engine; licensed to Jowett and produced by them for the Hillson Praga.
Ae39; AJJ2; S.
Applications: (Czechoslovakia) Praga E.114 (also built in the UK as the Hillson Praga). (France) Mignet H.M.14 Pou du Ciel [G-AEAD]. (Netherlands) de Schelde Scheldemeeuw [PH-ALK]; Scheldemusch [PH-AMG].
2cyl; Praga B-2; 40hp@2400rpm, 46@2510 (TO); 1938-1948; Wt = 106#.
Dual-ignition engine.
Ae39, Ae41; J47, J74-75 (for AVEX application); S; W47.
Applications: (Argentina) AVEX Yakstas Racer. (Italy) Alaparma A.M.10 Tucano.
O-175 -- {3.740 / 3.937 / 173.0} / {95 / 100 / 2835}
Same bore and stroke as O-345.
4cyl; Praga D; 60hp@2480rpm, 79@2610 (TO); 1937-1950; Wt = 143#.
Dual-ignition engine; type-tested in 1947 following ICAO international regulations.
Ae39, Ae41; AM11/83 (SK-1 application); AW; J47toJ49-50; S; W47.
Applications: (Czechoslovakia) Mraz M.2 Skaut; Praga E.114, E.115, E.117; Simunek/Kamarıt SK-1 Trempik homebuilt; Zlin 22. (France) Hurel-Dubois HD-10; Starck A.S. 80 Holiday. (Italy) Alaparma AM-75 Baldo; de Bernardi (formerly Partenavia) Aeroscooter; Meteor F.L.53. (Romania) Sovromtractor RG-6. (Yugoslavia) Letov KS-1C Jancz.
4cyl; Praga DR; 75hp@2850rpm, 90@3300 (TO); 1937-1942; Wt = 162#.
Dual-ignition engine; geared to 0.75.
Ae39, Ae41; S; W47.
Applications: None found.
4cyl; Praga DH; 83hp@N/A rpm; 1960-1961; Wt = N/A.
Dual-ignition helicopter engine.
J60-61 (for application).
Applications: (Czechoslovakia) Omnipol HC-2 Heli-Baby (prototype).
O-345 -- {3.740 / 3.937 / 346.1} / {95 / 100 / 5671}
Same bore and stroke as O-175.
8cyl; Praga E; 150hp@2650rpm; 1941-1948; Wt = 265#.
Dual-ignition engine.
J47; S; W47toW48.
Applications: None found.
8cyl; Praga ER; N/A hp@N/A rpm; 1941; Wt = N/A#
Dual-ignition engine; geared to 0.75 .
Ae41; S
Applications: None found
O-435 -- {4.528 / 4.528 / 437.4} / {115 / 115 / 7167}
6cyl; Praga Doris B; 200hp@2900rpm; 1956-1962; Wt = 436#.
Geared to 0.552 .
J56-57toJ61-62; S; W59-60toW62-63.
Applications: (Czechoslovakia) Avia L.60 Brigadyr; TOM-8 (L-208). (Poland) WSK M-2.