Hirth, Göbler-Hirthmotoren (Germany)

Hirth aircraft engines have a tradition dating from 1926. Hellmuth Hirth (1886-1938) was a son of Albert Hirth, a notable engineer and tool designer, and the brother of Wolfram (Wolf) Hirth (1900-1959), a famous sailplane designer and pilot. Hellmuth Hirth was a pioneer, pre-WWI, German military pilot. His engine company built mainly air-cooled, inverted inline engines for light aircraft from the 1920s through WWII. After his death, the firm was operated by the Civil Aviation Reichsministry in Germany until 1941, at which time the Heinkel organization took over Hirth operations. After WWII, Hirth became independent again and specialized in building two-stroke cycle engines for stationary use, snowmobiles, and then aircraft from 1965 to 1974. The Hirth firm went into voluntary liquidation in 1974. The assets were acquired shortly thereafter by Hans Göbler, who has built a broad range of two-stroke engines for many applications as the Göbler-Hirthmotoren GmbH of Benningen, Germany. In the 1980s, two-stroke Hirth engines were again built for light aircraft and production continues to the present. Two-stroke cycle HOAEs are part of the Hirth line, which also includes one-cylinder and two- and three-cylinder inline engines. Hirth is the major manufacturer of two-stroke HOAE in the 65-110hp range at the present time. Historical information can be found on the Hirth Website. The Type Certificates (TC) listed below as LBA refer to certification by the Luftfahrt Bundesamt (Federal Office of Civil Aviation), the German equivalent of the FAA in the US. Certification is to the European JAR requirements.

Hirth (Germany)

These are the engines built from 1965 to 1974 by the post-WWII Hirth company for light aircraft applications.

O-35 (2-Stroke) -- {2.283 / 2.126 / 34.8} / {58 / 54 / 571}

4cyl; F10A; 24hp@4800rpm, 26@5000 (TO); 1965-1974; Wt = 56#; LBA TC = 4568.
Single-ignition, geared, and produced in the following models:
F10A 1a, b, c with propeller shaft above the crankshaft; geared to 0.536, 0.455, 0.388, respectively;
F10A 2a, b, c with propeller shaft below the crankshaft; geared to 0.536, 0.455, 0.388, respectively.
F10K engines with the same 1a to 1c and 2a to 2c models are listed under the LBA TC; details of the differences have not been found. All applications are for powered gliders.
J65-66toJ75-76; W66-67.
Applications: (France) Fauvel AV.45. (Germany) Scheibe SF-24B Motorspatz, SF-25B Motorfalke, SF-27M self-launching sailplane with retractable engine above and behind the pilot; Schleicher K-12.

Göbler-Hirthmotoren (Germany)

Data and information on the current Göbler-Hirthmotoren engines can be found on the Hirth Website, and also from the US Hirth distributors, namely Adventure Ultralights, Inc. and Recreational Power Engineering.

O-23 (2-Stroke) -- {2.598 / 2.205 / 23.4} / {66 / 56 / 383}

2cyl; F22; 23hp@5000rpm; 1989-1993; Wt = 44-51#.
It is not clear whether it was produced in any quantity.
BGP; Brinks; J89-90toJ92-93.
Applications: None found.

O-32 (2-Stroke) -- {2.835 / 2.520 / 31.8} / {72 / 64 / 521}

Same bore and stroke as O-64.

2cyl; F23A; 40hp@5500rpm; 1988-present; Wt = 52-62#.
Dual-, capacitive-discharge ignition, direct drive available or reduction by belt drive (or gearing) to N/A; higher weight includes the gearing. An improved version was tested in 2002 and produced 50hp@6350rpm, as reported on their Website.
BGP; J89-90to present; KP4/05.
Applications: (Czech Republic) Airox F-31A twin. (Germany) Dornier MTC 11 helicopter. (US) Fisher 303, Skylight.

O-64 (2-Stroke) -- {2.835 / 2.520 / 63.6} / {72 / 64 / 1042}

Same bore and stroke as O-32.

4cyl; F30 series; 65hp@4500rpm-110@6500; 1987-present; Wt = 79# for direct drive, up to 130# with gearing.
Dual, capacitive-discharge ignition, direct drive available or reduction by belt drive (or gearing).
Other versions include F30 and F30E (E for fuel injection) with cogbelt rpm reduction to N/A, F30S and F30ES with Hirth G-40 gear box reduction to 0.300, 0.338, 0.379, 0.444, 0.493; all versions can have cooling fans installed and there is an H30ES version for helicopters. Performance and weight vary with the version chosen; the horsepower range is from 65 to110 depending on the gearing and state of tune.
BGP; J87-88to present; KP4/01, 4/02, 6/02, 4/03, 4/05.
Applications: (Czech Republic) Aeros UL-2000T Flamingo; Urban Air UFM-13/15. (Germany) Kaiser Whisper. (India) RAJ Hamsa Hanuman. (Italy) Dragon Fly 333 helicopter. (Romania) Aerostar 01. (Russian Federation) Dubna-2 Osa; Elitar IE-101; SAT Saviat E-4. (US) Air Command Commander Elite Single-Seat F-30, Tandem F-30 gyroplanes; Airdrome Aeroplanes Nieuport 24 (full-scale replica); American Sportscopter Ultrasport 496H Hornet helicopter; CGS Hawk II Arrow; Classic Aero Enterprises H-2 Honey-Bee; Kolb Mark III; Light Miniature Aircraft LM-2X-2P-W (87% scale Taylorcraft BC-12 replica); Little Wing LW-3, LW-3+2 gyroplanes; PAM 100B twin-engine flying platform; Para-Ski Top Gun F-30 powered parachute; RANS S-12; Rotor Flight Dynamics Dominator Draggin 2 gyroplane; SkyStar Kitfox; Titan Tornado; Vortech Skylark helicopter.

O-78 (2-Stroke) -- {N/A / N/A / 77.5} / {N/A / N/A / 1270}

4cyl; F30A; 80hp@4500rpm-130@6500; 1987-1993; Wt = 77# for direct drive, N/A for geared version.
Larger displacement version of O-64 with and without gearing to N/A; did not go into production. Performance and weight varied with the version chosen; the horsepower range was from 80 to130 depending on the gearing and state of tune.
BGP; J87-88toJ92-93.
Applications: None found.


Updated 1/17/06