{{infobox aero engine |name=125, 126, 127, 128, 129 and 131 |image=File:Alfa romeo storico aero engine 128RC 1939.jpg |caption=A {{convert|820|hp|kW|abbr=on|disp=flip}} Alfa Romeo 128 R.C.18 from ca1939. |engine_type=Piston aircraft engine |manufacturer=Alfa Romeo |first_run=1930s |number_built = ~11,000 |major_applications= Savoia-Marchetti SM.79 }}
Alfa Romeo built/designed a range of aircraft engines based on the Bristol Jupiter and Bristol Pegasus designs, designated '''Alfa 125''', '''Alfa 126''', '''Alfa 127''', '''Alfa 128''', '''Alfa 129''' and '''Alfa 131'''. All these essentially similar engines were mainly fitted to Italian bombers in World War II, Alfa Romeo building around 11,000 units between 1934 and 1944 <ref name="enzociliberto.it">{{cite web|url=http://www.enzociliberto.it/aisastoryauto/articolieriviste/galleryItaliano2006-2/Alfa_Romeo_factory_1933-45.pdf |format=PDF |title=STORY OF THE ALFA ROMEO FACTORY AND PLANTS page 12 |accessdate=2007-08-25 |work=enzociliberto.it |archiveurl=https://web.archive.org/web/20070929010114/http://www.enzociliberto.it/aisastoryauto/articolieriviste/galleryItaliano2006-2/Alfa_Romeo_factory_1933-45.pdf |archivedate=2007-09-29 |url-status=dead }}</ref>
==Design and development== Alfa Romeo adapted the Jupiter / Pegasus (which are very closely related) to metric measurements, local materials and indigenous equipment.
==Variants== thumb|right|Alfa Romeo 131, 9-cyl radial engine.
(The Italian engine designation system includes a suffix indicating major components or attributes. The most common were R for ''Riduttore'' - reduction gear and C for ''Compressore'' - compressor/supercharger, followed by a number indicating the rated altitude in hundreds of metres, two speed superchargers were indicated by a double figure such as 10/34). ;Alfa Romeo Jupiter: {{Main|Bristol Jupiter}} :The standard {{convert|313|kW|hp|abbr=on}} Jupiter engine built under licence from the Bristol Aeroplane Company.
;Alfa 125 R.C.10: rated at {{convert|1000|m|ft|abbr=on}}
;Alfa 125 R.C.35: 1934 — {{convert|485|kW|hp|abbr=on}} rated at {{convert|3500|m|ft|abbr=on}}
;Alfa 126 R.C.10: 1935 — Civilian version of 126 R.C.34 {{convert|559|-|597|kW|hp|abbr=on}} rated at {{convert|1000|m|ft|abbr=on}}
;Alfa 126 R.C.32: rated at {{convert|3200|m|ft|abbr=on}}
;Alfa 126 R.C.34: 1935 — {{convert|507|-|582|kW|hp|abbr=on}} rated at {{convert|3400|m|ft|abbr=on}}
;Alfa 127 R.C.50: rated at {{convert|5000|m|ft|abbr=on}}
;Alfa 127 R.C.55: 1937 — {{convert|560|kW|hp|abbr=on}} rated at {{convert|5500|m|ft|abbr=on}}
;Alfa 128 R.C.18: {{convert|641|-|717|kW|hp|abbr=on}} rated at {{convert|1800|m|ft|abbr=on}}
;Alfa 128 R.C.21: 1938 — {{convert|708|kW|hp|abbr=on}} rated at {{convert|2100|m|ft|abbr=on}}
;Alfa 129 R.C.32: rated at {{convert|3200|m|ft|abbr=on}}
;Alfa 131 R.C.14/50 :1943 — Two speed supercharger, rated at {{convert|1400|m|ft|abbr=on}} in low gear and {{convert|5000|m|ft|abbr=on}} in high gear.
==Applications== *Breda Ba.64 (Alfa125 R.C.35) *CANT Z.506A Airone (Alfa 126 R.C.10) *CANT Z.506B Airone (Alfa 126 R.C.34 / Alfa 127 R.C.50 / Alfa 127 R.C.55) *CANT Z.506C Airone (Alfa 126 R.C.10) *Caproni Bergamaschi AP.1 (Alfa126 R.C.34) *Caproni Ca.97 (AlfaJupiter)<ref name="alatricolore.it">{{cite web|url=http://www.alatricolore.it/alatricolore/storici/c/caproni/ca97.htm|title=CAPRONI CA.97|accessdate=2007-09-20|work=alatricolore.it}}</ref> *DAR-10A (prototype) (Alfa126 R.C.34) *Fiat G.12 (Alfa 128 R.C.18) *Junkers Ju 52 (Alfa126 R.C.34)<ref name="aerei-italiani.net">{{cite web|url=http://www.aerei-italiani.net/Marco_Rigoni/Alfa%20Romeo_Album%20Modelli%20Aerei_Nov.05.pdf|format=PDF|title=AlfaAEREI Collezione Modelli di Marco Rigoni Settembre 2005|accessdate=2007-04-25|work=aerei-italiani.net|archiveurl=https://web.archive.org/web/20070605150251/http://www.aerei-italiani.net/Marco_Rigoni/Alfa%20Romeo_Album%20Modelli%20Aerei_Nov.05.pdf|archivedate=5 June 2007|url-status=dead}}</ref> *Macchi M.C.94 (Alfa 126 R.C.10) *Macchi M.C.100 (Alfa 126 R.C.10)<ref name="Angelfire">{{cite web|url=https://www.angelfire.com/falcon/aecl/Fichier_histoire/1930_macchimc100.htm|title=Macchi M.C.100 - 1939|access-date=2007-09-20|work=Angelfire| archive-url= https://web.archive.org/web/20071031074858/http://www.angelfire.com/falcon/aecl/Fichier_histoire/1930_macchimc100.htm| archive-date= 31 October 2007 | url-status= live}}</ref> *Savoia-Marchetti S.73 (Alfa 126 R.C.10 / Alfa 126 R.C.34) *Savoia-Marchetti S.74 (Alfa126 R.C.34) *Savoia-Marchetti SM.75 Marsupiale (Alfa 128 R.C.18 / Alfa 128 R.C.21) *Savoia-Marchetti S.77 (Alfa 126 R.C.10) *Savoia-Marchetti S.M.79 Sparviero (Alfa 128 R.C.18 / Alfa 125 R.C.35 / Alfa126 R.C.34)<ref name="xs4all.nl/~fbonne/warbirds">{{cite web|url=http://www.xs4all.nl/~fbonne/warbirds/ww2htmls/savosm79.html|title=The Savoia-Marchetti S.M. 79 Sparviero|accessdate=2007-08-27|work=xs4all.nl/~fbonne/warbirds|archiveurl=https://web.archive.org/web/20070717225015/http://www.xs4all.nl/~fbonne/warbirds/ww2htmls/savosm79.html|archivedate=17 July 2007|url-status=dead}}</ref> *Savoia-Marchetti S.M.79-II Sparviero (Alfa 126 R.C.34) *Savoia-Marchetti S.M.79B Sparviero (Alfa 128 R.C.18) *Savoia-Marchetti S.M.81 Pipistrello (Alfa 125 R.C.35 / Alfa 126 R.C.34) *Savoia-Marchetti S.M.82 Canguru (Alfa 128 R.C.18 / Alfa 128 R.C.21 / Alfa 129 R.C.32) *Savoia-Marchetti S.M.83 (Alfa126 R.C.34) *Savoia-Marchetti S.M.84 (Alfa 128 R.C.21) *Savoia-Marchetti S.M.95 (Alfa 128 R.C.18 / Alfa 131 R.C.14/50)
==Specifications (Alfa 128 R.C.21)== {{pistonspecs| <!-- If you do not understand how to use this template, please ask at Wikipedia talk:WikiProject Aircraft --> <!-- Please include units where appropriate (main comes first, alt in parentheses). If data are missing, leave the parameter blank (do not delete it). --> |ref=Aircraft Engines of the World 1945<ref name="Wilkinson1946">{{cite book |last=Wilkinson |first=Paul H. |title=Aircraft engines of the World 1945 |year=1945 |publisher=Paul H. Wilkinson |location=New York |pages=288–289 |edition=2nd}}</ref> Archivio Storico Alfa Romeo - Volume II<ref name="ReferenceA">Archivio Storico Alfa Romeo - Volume II. Torino, November 1998</ref> |type=9-cylinder air-cooled radial engine |bore={{convert|146|mm|in|abbr=on|2}} |stroke={{convert|190|mm|in|abbr=on|2}} |displacement={{convert|28.6|L|cuin|abbr=on|2}} |length={{convert|1329|mm|in|abbr=on|1}} |diameter={{convert|1400|mm|in|abbr=on|1}} |width= |height= |weight={{convert|516|kg|lb|abbr=on|0}} |valvetrain=2 x inlet valves and 2 x exhaust valves per cylinder operated by pushrods and rockers |supercharger=Gear-driven 1-speed, 8.8:1 ratio, supercharger |turbocharger= |fuelsystem=1 x Mona-Hobson AVT85MC updraught carburettor with automatic boost control |fueltype=87 octane |oilsystem={{convert|80|psi|kPa|abbr=on|1|disp=flip}}, dry sump. |coolingsystem=Air-cooled |power= {{unordered list |'''Take-off:''' {{convert|950|hp|kW|abbr=on|0|disp=flip}} at 2,300 rpm with {{convert|1000|mm|in|abbr=on|2}} Hg boost |'''Military:''' {{convert|860|hp|kW|abbr=on|0|disp=flip}} at 2,300 rpm at {{convert|2100|m|ft|abbr=on}} |'''Cruising:''' {{convert|660|hp|kW|abbr=on|0|disp=flip}} at 1,800 rpm at {{convert|2500|m|ft|abbr=on}} }} |specpower= 24.57 kW/L (0.54 hp/cu in) |compression=7:1 |specfuelcon=0.31 kg/kW/hr (0.51 lb/hp/hr) (take-off) |oilcon=0.0078 kg/kW/hr (0.013 lb/hp/hr) |power/weight=0.782 kW/kg (0.775 hp/lb)
|designer= |reduction_gear=Epicyclic bevel reduction gear, 0.65:1 ratio.
|general_other='''Frontal Area:''' {{convert|1.54|m2|sqft|abbr=on|1}} |components_other='''Starter:''' Garelli compressed air starter *'''Ignition:''' 2 x Marelli MF9 magnetos, 2 x spark plugs per cylinder, fed by a shielded harness. }}
==See also== {{aircontent <!-- first, the related articles that do not fit the specific entries: --> |see also=
<!-- designs which were developed into or from this aircraft or engine: --> |related=
<!-- aircraft that are of similar role, era, and capability as this design: --> |similar aircraft=
<!-- relevant lists that this aircraft appears in: --> |lists= *List of aircraft engines <!-- For aircraft engine articles. Engines that are of similar to this design: --> |similar engines= * BMW 132 * Bristol Pegasus * Nakajima Hikari * Wright R-1820 Cyclone
<!-- See WP:Air/PC for more explanation of these fields. --> }}
==References== '''Notes''' {{reflist}} '''Bibliography''' {{refbegin}} *{{cite book |last=Wilkinson |first=Paul H. |title=Aircraft engines of the World 1945 |year=1945 |publisher=Paul H. Wilkinson |location=New York |pages=288–289 |edition=2nd}} *Archivio Storico Alfa Romeo - Volume II. Torino, November 1998 {{refend}}
{{Alfa Romeo aeroengines}}
Category:1930s aircraft piston engines Category:Aircraft air-cooled radial piston engines 125 Category:Nine-cylinder engines