Hirth 3701
{{Short description|German two-stroke aircraft engine}}
{{Use dmy dates|date=March 2022}}
{{Use British English|date=January 2022}}
| {{Infobox aircraft begin
| name=Hirth 3701 | image= | caption= }}{{Infobox Aircraft Engine |type=Three-cylinder two-stroke aircraft engine |manufacturer=Hirth |national origin=Germany |first run= |major applications= |produced= |number built= |developed from= |variants with their own articles= }} |
The Hirth 3701 is an in-line three-cylinder, two-stroke, carburetted aircraft engine, with optional fuel injection, designed for use on ultralight aircraft and small homebuilts. It is manufactured by Hirth of Germany.{{cite web|url=http://www.recpower.com/3701.htm |title=3701S – 2 cycle 100hp |accessdate=18 December 2009 |last=Recreational Power Engineering |archiveurl=https://web.archive.org/web/20060311024349/http://www.recpower.com/3701.htm |archivedate=11 March 2006 |url-status=dead }}{{cite web|url = http://www.ultraligero.net/Descargas/Manuales/Hirth/3701_2cycle_100Hp.htm|title = 3701–2 cycle – 100hp |accessdate=18 December 2009 |last=Ultraligero.Net}}
Development
The 3701 was developed as a liquid-cooled and narrower installation alternative to the four-cylinder Hirth F-30 air-cooled engine of {{convert|85|to|110|hp|kW|0|abbr=on}}.
The 3701 features triple Bing 34 mm slide carburetors or optionally fuel injection. The cylinder walls are electrochemically coated with Nikasil. Standard starting is electric start and recoil start is not available as an option. The reduction drive system available is the G-50 gearbox, with reduction ratios of 2.16:1, 2.29:1, 2.59:1, 3.16:1, or 3.65:1.
The engine runs on a 50:1 pre-mix of unleaded 93 octane auto fuel and oil, or optionally 100:1 oil injection.
Variants
;3701 high-torque/low-rpm engine
:Three-cylinder in-line, two-stroke aircraft engine with three Bing 34 mm slide carburetors or fuel injection. Low piston port timing produces {{convert|84|hp|kW|0|abbr=on}} at 4950 rpm with a very flat torque curve.
;3701 high performance engine
:Three-cylinder in-line, two stroke aircraft engine with three Bing 34 mm slide carburetors or fuel injection. High piston port timing produces {{convert|100|hp|kW|0|abbr=on}} at 6000 rpm with a steep torque curve.
Applications
{{columns-list|colwidth=30em|
- Alliant Destiny Fusion
- Alliant Destiny XLT
- CGS Hawk II Arrow
- Eagle Helicycle{{cite web|url = http://www.helicycle.com/Flying%20Ships/index.htm |title=Helicycle |accessdate=18 December 2009 |last = Von Koschier|first = Angelo|date=November 2003}}
- Earthstar Thunder Gull II
- Quicksilver MX II
- InterPlane Skyboy
- Rans S-9 Chaos
- Zenair CH 601 Zodiac
}}
Specifications (3701 high performance)
{{pistonspecs|
|ref=Recreational Power Engineering
|type=Three-cylinder, two-stroke, in-line, aircraft engine
|bore={{convert|76|mm|in|1|abbr=on}}
|stroke={{convert|69|mm|in|1|abbr=on}}
|displacement=939 cc (57.3 cu in)
|length={{convert|490|mm|in|1|abbr=on}}
|diameter=
|width={{convert|280|mm|in|1|abbr=on}}
|height={{convert|420|mm|in|1|abbr=on}}
|weight={{convert|108|lb|kg|1|abbr=on}}, including electric starter and exhaust system. With optional gearbox total weight is {{convert|127|lb|kg|1|abbr=on}}, plus radiator.
|valvetrain=piston ported
|supercharger=
|turbocharger=
|fuelsystem=3 X Bing 34 mm slide type carburetors or fuel injection
|fueltype=unleaded 93 octane auto fuel
|oilsystem=50:1 fuel/oil premix or oil injection
|coolingsystem=liquid
|power={{convert|100|hp|kW|0|abbr=on}} at 6000 rpm
|specpower=
|compression=9.5:1
|fuelcon=
|specfuelcon=
|oilcon=
|power/weight=
|designer=
|reduction_gear= G-50 gearbox with reduction ratios of 2.16:1, 2.29:1, 2.59:1, 3.16:1, or 3.65:1
|general_other=
|components_other=
|performance_other=
}}
See also
References
{{Reflist}}
External links
- {{Official website|https://web.archive.org/web/20101115000000*/http://www.recpower.com/2703.htm}} on Archive.org
{{Hirth aeroengines}}
Category:Hirth aircraft engines