The Hirth F-33 is a

single cylinder A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery ...

two stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...

, carburetted aircraft engine designed for use on ultralight aircraft, including powered paragliders and

ultralight trike An ultralight trike is a type of powered hang glider where flight control is by weight-shift. These aircraft have a fabric flex-wing from which is suspended a tricycle fuselage pod driven by a pusher propeller. The pod accommodates either a ...

s. the engine is noted for its extremely light base weight of . It is manufactured by

Hirth Hirth Engines GmbH is an engine manufacturer based in Benningen, Germany. It is currently a part of the UMS Aero Group. Hirth began manufacturing aero engines in the 1920s, was taken over by Heinkel in WWII to develop the Heinkel-Hirth jet en ...

of Germany.Cliche, Andre: ''Ultralight Aircraft Shopper's Guide'' 8th Edition, page G-3 Cybair Limited Publishing, 2001. Purdy, Don: ''AeroCrafter - Homebuilt Aircraft Sourcebook'', page 72. BAI Communications.

Development

The F-33 was intended to fill the niche previously occupied by the now out-of-production

Rotax 277 The Rotax 277 is a , single-cylinder, two-stroke aircraft engine, that was built by BRP-Rotax GmbH & Co. KG of Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Euro ...

. The F-33 uses free air cooling, dual

capacitor discharge ignition Capacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It ...

and reed valve induction, with a single Bing 34mm slide or optional diaphragm type carburetor. The cylinder walls are electrochemically coated with

Nikasil Nikasil is a trademarked electrodeposited lipophilic nickel matrix silicon carbide coating for engine components, mainly piston engine cylinder liners. Development Nikasil was introduced by Mahle in 1967, and initially developed to allow Wanke ...

. Standard starting is

recoil start Rope start (also called pull start or ''rewind start'') is a method of starting an internal combustion engine, usually on small machines, such as lawn mowers, chainsaws, ultralight aircraft, small outboard motors and portable engine-generators. A ...

. A belt reduction drive system, fuel injection, tuned exhaust and electric start are optional. The engine runs on a 50:1 pre-mix of unleaded 93 octane auto fuel and oil. Recommended time between overhauls is 1000 hours. The F-33 produces at 5200 rpm and at 6500 rpm.

Applications

Specifications (F-33)

References

External links

* {{Hirth aeroengines Hirth aircraft engines Air-cooled aircraft piston engines Two-stroke aircraft piston engines