Main Menu

Bristol Jupiter
Gnome-Rhône 9 Jupiter
Cosmos Jupiter
Bristol Orion
Brazil Straker Jupiter I

Walter Jupiter
Siemens-Halske Sh20 / Sh21
Nakajima Ha-1 Kotobuki
PZL Bristol Jupiter
Weiss - Bristol Jupiter VI




The Jupiter was designed during World War I by Roy Fedden of Cosmos Engineering as the Cosmos Jupiter. During the rapid downscaling of military spending after the war, Cosmos became bankrupt in 1920, and was eventually purchased by the Bristol Aeroplane Company on the strengths of the Jupiter design and the encouragement of the Air Ministry. First run on 29 October 1918 the engine matured into one of the most reliable on the market. It was the first air-cooled engine to pass the Air Ministry full-throttle test, the first to be equipped with automatic boost control, and the first to be fitted to airliners.

The Jupiter was fairly standard nine-cylinder single-row piston radial engine in design, but featured four valves per cylinder, which was uncommon at the time. The cylinders were machined from steel forgings, and the cast cylinder heads were later replaced with aluminium alloy following studies by the RAE. In 1927, a change was made to move to a forged head design due to the rejection rate of the castings. The Jupiter VII introduced a mechanically driven supercharger to the design, and the Jupiter VIII was the first to be fitted with reduction gear.

In 1925, Fedden started designing a replacement for the Jupiter. Using a shorter stroke to increase the rpm, and including a supercharger for added power, resulted in the Bristol Mercury of 1927. Applying the same techniques to the original Jupiter-sized engine in 1927 resulted in the Bristol Pegasus. Neither engine would fully replace the Jupiter for a few years.

A 1926 turbo-supercharged version of the Jupiter known as the Orion suffered development problems and only a small number were produced. Metallurgy problems with this turbo-supercharged engine caused the project to be abandoned after only nine engines had been built.

The Jupiter saw widespread use in licensed versions, with fourteen countries eventually producing the engine. In France, Gnome-Rhone produced a version known as the Gnome-Rhône 9 Jupiter which was used in several local civilian designs, as well as achieving some export success. Siemens-Halske took out a license in Germany and produced several versions of increasing power, eventually resulting in the Bramo 323 Fafnir, which saw use in wartime models.



In Japan, the Jupiter was license-built from 1924 by Nakajima, forming the basis of their own subsequent radial aero-engine design, the Nakajima Ha-1 Kotobuki. It was produced in Poland as the PZL Bristol Jupiter, in Italy as the Alfa Romeo 126-RC35,[6] and in Czechoslovakia by Walter Engines. The most produced version was in the Soviet Union, where their Shvetsov M-22 version powered the famous Polikarpov I-16 which was built in the thousands. Production started in 1918 and ceased in 1930 after more than 7100 were built.

The Jupiter is probably best known for powering the Handley Page HP.42 Hannibal airliners, which flew the London-Paris route in the 1930s. Other civilian uses included the de Havilland Giant Moth and Hercules, the Junkers G 31, and the Dornier Do X flying boat which used twelve engines.
Military uses included the parent company's Bristol Bulldog, as well as the Gloster Gamecock and Boulton Paul Sidestrand. It was also found in prototypes from Japan to Sweden.

By 1929 the Bristol Jupiter had flown in 262 different aircraft types, it was noted in the French press at that year's Paris Air Show that the Jupiter and its license-built versions were powering 80% of the aircraft on display.


Brazil Straker Jupiter I
(1918) 400 hp. Two built.

Cosmos Jupiter II
(1918) 400 hp. One built.

Bristol Jupiter II
(1923) 400 hp.

Bristol Jupiter III
(1923) 400 hp.

Bristol Jupiter IV
(1926) 430 hp. Variable valve timing, Bristol Triplex carburettor.

Bristol Jupiter V
(1925) 480 hp.

Bristol Jupiter VI
(1927) 520 hp. Produced in both high (6.3:1) and low (5.3:1) compression ratios.

Bristol Jupiter VIA
(1927) 440 hp. Civil version of Jupiter VI.

Bristol Jupiter VIFH
(1932) 440 hp. Equipped with gas starter motor.

Bristol Jupiter VIFL
(1932) 440 hp. Compression ratio 5.15:1.

Bristol Jupiter VIFM
(1932) 440 hp. Compression ratio 5.3:1.

Bristol Jupiter VIFS
(1932) 400 hp. Compression ratio 6.3:1.

Bristol Jupiter VII
(1928) 375 hp. Compression ratio 5.3:1, fully supercharged. Built by Gnome-Rhone as the 9ASB.

Bristol Jupiter VIIF
(1929) 480 hp. Compression ratio 5.3:1. Forged cylinder heads.

Bristol Jupiter VIIF.P
(1930) 480 hp. 'P' for pressure feed lubrication to wrist-pins.

Bristol Jupiter VIII
(1929) 440 hp. Jupiter VI but compression ratio increased to 6.3:1.

Bristol Jupiter VIIIF
(1929) 460 hp. Jupiter VIII with forged cylinder heads and lowered compression ratio (5.8:1).

Bristol Jupiter VIIIF.P
(1929) 460 hp. As Jupiter VIII with pressure feed lubrication (TBO at this stage in development was only 150 hours due to multiple failures).

Bristol Jupiter IX
480 hp. Compression ratio 5.3:1.

Bristol Jupiter IXF
550 hp. Compression ratio 5.3:1. Forged cylinder heads.

Bristol Jupiter X
470 hp. Compression ratio 5.3:1.

Bristol Jupiter XF
540 hp. Compression ratio 5.3:1. Forged cylinder heads.

Bristol Jupiter XFA
483 hp. Compression ratio 5.3:1.

Bristol Jupiter XFAM
580 hp.

Bristol Jupiter XFBM
580 hp.

Bristol Jupiter XFS
Fully supercharged.

Bristol Jupiter XI
Compression ratio 5.15:1.

Bristol Jupiter XIF
500 hp. Compression ratio 5.15:1.

Bristol Jupiter XIFA
480 hp. As Jupiter XIF with 0.656:1 reduction ratio

Bristol Jupiter XIF.P
525 hp. As Jupiter XIF with pressure feed lubrication.

Bristol Orion I
(1926) Jupiter III, turbo-supercharged, abandoned programme.


Siemens-Halske Sh20, Sh21 and Sh22
Siemens-Halske took out a license in Germany and produced several versions of increasing power, eventually resulting in the Bramo 323 Fafnir, which saw use in wartime models.


Nakajima Ha-1 Kotobuki
In Japan, the Jupiter was license-built from 1924 by Nakajima.


PZL Bristol Jupiter
Polish production.


Alfa Romeo Jupiter
Italian licence production, 420 hp (310 kW).


Alfa 126 R.C.35
Alfa Romeo developed variant


Walter Jupiter
Licence production in Czechoslovakia by Walter Engines


Weiss - Bristol Jupiter VI


Cosmos Jupiter:
Bristol Badger
Bristol Bullet
Sopwith Schneider
Westland Limousine

Bristol Jupiter:
Aero A.32
Airco DH.9
Arado Ar 64
Avia BH-25
Bernard 190
Blériot-SPAD 51
Blériot-SPAD S.56
Boulton & Paul Bugle
Boulton Paul P.32
Boulton Paul Partridge
Boulton Paul Sidestrand
Blackburn Beagle
Blackburn Nile
Blackburn Ripon
Bristol Badger
Bristol Badminton
Bristol Bagshot
Bristol Beaver
Bristol Bloodhound
Bristol Boarhound
Bristol Brandon
Bristol Bulldog
Bristol Bullfinch
Bristol Jupiter Fighter
Bristol Seely
Bristol Type 72
Bristol Type 75
Bristol Type 76
Bristol Type 89
Bristol Type 92
Bristol Type 118
de Havilland Dingo
de Havilland DH.72
de Havilland DH.50
de Havilland Dormouse
de Havilland Hercules
de Havilland Hound
de Havilland Giant Moth
de Havilland Survey
Dornier Do 11
Dornier Do J
Dornier Do X
Fairey IIIF
Fairey Ferret
Fairey Flycatcher
Fairey Hendon
Fokker C.V
Fokker F.VIIA
Fokker F.VIII
Fokker F.IX
Gloster Gambet
Gloster Gamecock
Gloster Gnatsnapper
Gloster Goldfinch
Gloster Goring
Gloster Grebe
Gloster Mars
Gloster Survey
Gourdou-Leseurre LGL.32
Handley Page Clive
Handley Page Hampstead
Handley Page Hare
Handley Page Hinaidi
Handley Page HP.12
Handley Page H.P.42
Hawker Duiker
Hawker Harrier
Hawker Hart
Hawker Hawfinch
Hawker Hedgehog
Hawker Heron
Hawker Woodcock
Junkers F.13
Junkers G 31
Junkers W 34
Parnall Plover
Saunders Medina
Saunders Severn
Short Calcutta
Short Chamois
Short Gurnard
Short Kent
Short Rangoon
Short Scylla
Short Springbok
Short S.6 Sturgeon
Short Valetta
Supermarine Seagull
Supermarine Solent
Supermarine Southampton
Svenska Aero Jaktfalken
Tupolev I-4
Vickers F.21/26
Vickers F.29/27
Vickers Jockey
Vickers Type 143
Vickers Type 150
Vickers Valiant
Vickers Vellore
Vickers Vellox
Vickers Vespa
Vickers Viastra
Vickers Victoria
Vickers Vildebeest
Vickers Vimy
Vickers Vimy Trainer
Vickers Wibault Scout
Westland Interceptor
Westland Wapiti
Westland Westbury
Westland Witch
Westland-Houston PV.3

Gnome-Rhône Jupiter:
Bernard SIMB AB 12
Blanchard BB-1
Fizir F1M-Jupiter
Latécoère 6

Shvetsov M-22:
Kalinin K-5
Polikarpov I-5
Polikarpov I-15
Polikarpov I-16
Tupolev I-4


Jupiter XFA
Type: Nine-cylinder, naturally aspirated, air-cooled radial engine
Bore: 5.75 in (146 mm)
Stroke: 7.5 in (190 mm)
Displacement: 1,753 in³ (28.7 L)
Diameter: 54.5 in (1,384 mm)
Dry weight: 995 lb (451 kg)
Valvetrain: Overhead poppet valve, four valves per cylinder, two intake and two exhaust
Supercharger: Single speed, single stage
Fuel type: 73-77 Octane petrol
Cooling system: Air-cooled
Power output:
550 hp (414 kW) at 2,200 rpm at 11,000 ft (3,350 m) - maximum power limited to five minutes operation.
525 hp (391 kW) at 2,000 rpm - maximum continuous power at 11,000 ft (3,350 m)
483 hp (360 kW) at 2,000 rpm - takeoff power
Specific power: 0.31 hp/in³ (14.4 kW/L)
Compression ratio: 5.3:1
Power-to-weight ratio: 0.55 hp/lb (0.92 kW/kg)


Copyright © 2021 all-aero. All Rights Reserved.
Joomla! is Free Software released under the GNU General Public License.