# Hirth F-33 > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Hirth_F-33 > Markdown URL: https://mediated.wiki/source/Hirth_F-33.md > Source: https://en.wikipedia.org/wiki/Hirth_F-33 > Source revision: 1350764528 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) German two-stroke aircraft engine Hirth F-33 Type Single-cylinder two-stroke aircraft engine National origin Germany Manufacturer Hirth The **Hirth F-33** is a [single-cylinder](/source/Single-cylinder_engine), [two-stroke](/source/Two-stroke), [carburetted](/source/Carburetor) aircraft engine designed for use on [ultralight aircraft](/source/Ultralight_aircraft), including [powered paragliders](/source/Powered_paragliding) and [ultralight trikes](/source/Ultralight_trike). The engine is noted for its extremely light base weight of 35 lb (16 kg). It is manufactured by [Hirth](/source/Hirth) of Germany.[1][2][3] ## Development The F-33 was intended to fill the niche previously occupied by the now out-of-production 28 hp (21 kW) [Rotax 277](/source/Rotax_277). The F-33 uses free air cooling, dual [capacitor discharge ignition](/source/Capacitor_discharge_ignition) and reed valve induction, with a single Bing 34mm slide or optional diaphragm type carburetor. The cylinder walls are electrochemically coated with [Nikasil](/source/Nikasil). Standard starting is [recoil start](/source/Recoil_start). A belt reduction drive system, [fuel injection](/source/Fuel_injection), tuned exhaust and electric start are optional.[1][2] The engine runs on a 50:1 pre-mix of [unleaded 93 octane auto fuel](/source/Avgas#Automotive_gasoline) and oil. Recommended time between overhauls is 1000 hours.[1][2] The F-33 produces 22 hp (16 kW) at 5200 rpm and 28 hp (21 kW) at 6500 rpm.[1][2] ## Applications - [Aerosport OY Spider](/source/Aerosport_OY_Spider) - [Aerolite 103](/source/Aerolite_103) - [Alpaero Exel](/source/Alpaero_Exel) - [Ameri-Cana Eureka](/source/Ameri-Cana_Eureka) - [APEV Pouchel II](/source/APEV_Pouchel_II) - [Arey Tatush](/source/Arey_Tatush) - [Av8er Explorer](/source/Av8er_Explorer) - [Belite Aircraft Superlite](/source/Belite_Aircraft_Superlite) - [Büttner Crazy Flyer](/source/B%C3%BCttner_Crazy_Flyer) - [Büttner Crazy Plane](/source/B%C3%BCttner_Crazy_Plane) - [DAR Solo](/source/DAR_Solo) - [Earthstar Gull 2000](/source/Earthstar_Gull_2000) - [Escapade Kid](/source/Escapade_Kid) - [Fisher Avenger](/source/Fisher_Avenger) - [Fisher FP-505 Skeeter](/source/Fisher_FP-505_Skeeter) - [Fisher FP-606 Sky Baby](/source/Fisher_FP-606_Sky_Baby) - [Fresh Breeze Airbass Monster](/source/Fresh_Breeze_Airbass_Monster) - [Fresh Breeze Flyke](/source/Fresh_Breeze_Flyke) - [Fresh Breeze Respect Monster](/source/Fresh_Breeze_Respect_Monster) - [Fresh Breeze Monster](/source/Fresh_Breeze_Monster) - [Ivanov ZJ-Viera](/source/Ivanov_ZJ-Viera) - [JDT 1030F MAX-103](/source/Mini-MAX) - [JDT 1100F Mini-MAX](/source/Mini-MAX) - [Howland H-3 Pegasus](/source/Howland_H-3_Pegasus) - [Hummel CA-2](/source/Hummel_CA-2) - [M-Squared Breese XL](/source/M-Squared_Breese_XL) - [Paladin Sparrow](/source/Paladin_Sparrow) - [Phoenix Skywalker 330](/source/Phoenix_Skywalker_330) - [Pipistrel Apis-Bee](/source/Pipistrel_Apis-Bee) - [PowerTrike Light](/source/PowerTrike_Light) - [Quad City Challenger](/source/Quad_City_Challenger) - [Roll Flight MR V](/source/Roll_Flight_MR_V) - [SDB Karat](/source/SDB_Karat) - [Silent Family Silent Glider M](/source/Silent_Family_Silent_Glider_M) - [Spacek SD-1 Minisport](/source/Spacek_SD-1_Minisport) - [Spartan BP Parawing](/source/Spartan_BP_Parawing) - [Spartan DFS Paramotor](/source/Spartan_DFS_Paramotor) - [Spartan DFS Trike](/source/Spartan_DFS_Trike) - [Sperwill ST](/source/Sperwill_ST) - [TeST TST-3 Alpin T](/source/TeST_TST-3_Alpin_T) - [Trio-Twister 103](/source/Trio-Twister_103) - [Wings of Freedom Flitplane](/source/Wings_of_Freedom_Flitplane) - [Wood Sky Pup](/source/Wood_Sky_Pup) ## Specifications (F-33) *Data from* Recreational Power Engineering[2] ### General characteristics - **Type:** Single-cylinder, two-stroke, aircraft engine - **[Bore](/source/Bore_(engine)):** 76 mm (3.0 in) - **[Stroke](/source/Stroke_(engine)):** 69 mm (2.7 in) - **[Displacement](/source/Engine_displacement):** 313 cc (19.1 cu in) - **Length:** 300 mm (11.8 in) - **Width:** 299.5 mm (11.8 in) - **Height:** 380 mm (15.0 in) - **[Dry weight](/source/Dry_weight):** 31 lb (14.1 kg) (base weight) 45 lb (20.4 kg) (with electric start and reduction drive) ### Components - **[Valvetrain](/source/Valvetrain):** [Reed valve](/source/Reed_valve), piston-ported - **Fuel system:** 1 X Bing 34mm slide or optional diaphragm type carburetor or fuel injection - **Fuel type:** Minimum of unleaded 93 octane auto fuel - **Oil system:** 50:1 fuel-oil premix - **Cooling system:** free air - **[Reduction gear](/source/Propeller_speed_reduction_unit):** four element cog belt ### Performance - **Power output:** 28 hp (21 kW) at 6500 rpm - **[Compression ratio](/source/Compression_ratio):** 9.5:1 - **[Power-to-weight ratio](/source/Power-to-weight_ratio):** 0.8 ## References 1. ^ [***a***](#cite_ref-Cliche_1-0) [***b***](#cite_ref-Cliche_1-1) [***c***](#cite_ref-Cliche_1-2) [***d***](#cite_ref-Cliche_1-3) Cliche, Andre: *Ultralight Aircraft Shopper's Guide* 8th Edition, page G-3 Cybair Limited Publishing, 2001. [ISBN](/source/ISBN_(identifier)) [0-9680628-1-4](https://en.wikipedia.org/wiki/Special:BookSources/0-9680628-1-4) 1. ^ [***a***](#cite_ref-F33_2-0) [***b***](#cite_ref-F33_2-1) [***c***](#cite_ref-F33_2-2) [***d***](#cite_ref-F33_2-3) [***e***](#cite_ref-F33_2-4) Recreational Power Engineering (n.d.). ["F-33 2 cycle 28hp"](http://www.recpower.com/F-33%202%20cycle%2028hp.htm). Retrieved 17 January 2013. 1. **[^](#cite_ref-Aerocrafter_3-0)** Purdy, Don: *AeroCrafter - Homebuilt Aircraft Sourcebook*, page 72. BAI Communications. [ISBN](/source/ISBN_(identifier)) [0-9636409-4-1](https://en.wikipedia.org/wiki/Special:BookSources/0-9636409-4-1) ## External links - [Official website](https://hirthengines.com/2-stroke-engines/33-series) v t e Hirth and Heinkel-Hirth aircraft engines Piston engines HM 8 HM 60 HM 150 HM 500 HM 501 HM 504 HM 506 HM 508 HM 512 HM 515 Two-strokes F-23 F-30 F-33 F-36 F-40 F-263 2302 2702 2703 2704 2706 3002 3003 3202 3203 3502 3503 3701 3702 3703 4103 4201 Gas turbines HeS 1 HeS 3 HeS 8 HeS 30 HeS 40 HeS 50 HeS 60 HeS 011 --- Adapted from the Wikipedia article [Hirth F-33](https://en.wikipedia.org/wiki/Hirth_F-33) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Hirth_F-33?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.