Rapp 300 hp
| Industry | Aircraft engine manufacturing |
|---|---|
| Founded | circa 1915 |
| Products | Aircraft engines (e.g. Rapp 200 hp V-8, Rapp 300 hp V-12) |
The Rapp 200 hp was a water-cooled V-8 aircraft powerplant with a 90° configuration, produced by Rapp Motorenwerke.
Design and development
The conceptual basis for the Rapp 200 hp V-8 engine was the earlier Rapp 100 hp four-cylinder model, with its development dating to around 1915.[1] This power unit featured eight cylinders sharing identical bore and stroke dimensions of 140 mm × 160 mm (5.51 in × 6.30 in) as the Rapp 100 hp, arranged in two banks of four cylinders each.[2][3] The engine was rated to deliver approximately 200–205 hp (149–153 kW) at 1,350 rpm and had a mass close to 300–315 kg (661–694 lb).[2][3][4][5]
Its cylinder and valve train architecture closely mirrored that of the preceding Rapp 100 hp four-cylinder engine.[3][1] Each bank's cylinders were grouped in pairs, each consisting of two distinct forged steel liners screwed into paired cast cylinder heads. These cylinder heads incorporated integral cooling jackets and were cast from steel in pairs before undergoing machining.[3]
Valve seats were manufactured as separate components; exhaust valve seats were water-cooled and all seats were screwed into the cylinder heads to facilitate straightforward maintenance.[3][1] For each pair of cylinders, both inlet valves shared a single pivoted leaf spring pressing them onto their seats, mirrored by the exhaust valves on the opposite side. Intake ports faced inward toward the Vee's centerline, while exhaust ports were oriented outward.
Valve actuation for both intake and exhaust valves on each cylinder was sequentially managed by a single cam lobe on an overhead camshaft through roller tappets and rocker arms.[3][6] The camshaft for each cylinder bank was driven via a vertical timing shaft equipped with bevel gears positioned between the paired cylinders. Two magnetos, also driven from this vertical shaft, were mounted centrally between the two cylinder banks.[3][1]
Constructed in two halves split along the centerline into upper and lower sections, the aluminum crankcase design followed the same principles used in the Rapp 100 hp four-cylinder and the Rapp Rp III six-cylinder (150 hp) engines.[7] The crankshaft was supported by main journals housed in the upper crankcase half.[7] Lubrication was provided by a gear-driven oil pump mounted at the engine’s lowest point,[3] which circulated oil from two cylindrical reservoirs located front and rear beneath the crankcase to lubricate the crankshaft’s main journals.
Separate geared water pumps were installed on each side of the crankcase to circulate coolant individually for each bank of cylinders.[3][1]
The engine utilized two Zenith-style[7] carburettors, each supplying fuel-air mixture independently to one bank of four cylinders. Various configurations for carburettor placement were experimented with; some units had carburettors mounted at the rear of the engine,[3] while others positioned them between the cylinder banks.[1] Additionally, intake air could be preheated by routing it through pipes warmed by exhaust gases before entering the carburettors.[3]
Rapp 300 hp V-12
This engine configuration was also adapted into a 60° V-12 layout.[8] The Rapp 300 hp V-12 reportedly delivered approximately 300 hp (224 kW) at around 1,350 to 1,400 rpm, with a weight close to 470–474 kg (1,036–1,045 lb).[3][5] Various versions seem to have been tested featuring exhaust ports oriented both outward[9] and inward[8] facing configurations, the latter sometimes shown equipped with Pallas carburetors.
Variants
- 200 hp Rapp V-8[3]
- Circa 1915, rated at 200 hp (149 kW), operating between 1,350 and 1,400 rpm, with a bore and stroke of 140 mm × 160 mm (5.5 in × 6.3 in)[2][4][5]
- 300 hp Rapp V-12[3]
- Circa 1915, outputting around 300 hp (224 kW) at 1,350–1,400 rpm, featuring the same bore and stroke dimensions of 140 mm × 160 mm (5.5 in × 6.3 in)[5]
Specifications (200 hp Rapp V-8)
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 BMW Group Archives. Achtzylinder Rapp - Flugmotor, 200 PS (photo)
- ↑ 2.0 2.1 2.2 Angle. 1921. p. 402
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 Huth. 1920. p. 145-147, 130-134
- ↑ 4.0 4.1 Eyb. 1918. p. 125
- ↑ 5.0 5.1 5.2 5.3 Klamroth. 1916. p. 235
- ↑ cf. Der Motorwagen. 20 January 1918. pp. 14-15
- ↑ 7.0 7.1 7.2 Schwager. 1918. pp. 114–115
- ↑ 8.0 8.1 BMW Group Archives. Zwölfzylinder Rapp - Flugmotor, 300 PS.
- ↑ BMW Group Archives. Flugmotorenprüfstände der Rapp Motoren-Werke (photo). 60° V-12 in the middle, note the outward-facing exhausts
Bibliography
- Angle, Glenn Dale (1921). Airplane Engine Encyclopedia: An Alphabetically Arranged Compilation Of All Available Data On The World's Airplane Engines. Otterbein Press. pp. 402-404. OL 23525261M.
- Eyb, Robert (1918). Fliegerhandbuch (in Deutsch) (3rd ed.). Berlin: R.C. Schmidt & Co. OCLC 9500053.
- Huth, Fritz (1920). Motoren für Flugzeuge und Luftschiffe (in Deutsch) (3rd ed.). Berlin: R. C. Schmidt & co. OCLC 2116726.
- Klamroth, Gerhard (1916). Schiffsmaschinenkunde mit besonderer Berücksichtigung der Dampfturbinen und Ölmotoren (in Deutsch). Berlin: E.S. Mittler und Sohn.
- "Zur Konstruktion der Steuerung". Der Motorwagen (in Deutsch). 21 (2). Berlin: Krayn: 13–16. 20 January 1918.
- Rapp. "Achtzylinder Rapp - Flugmotor, 200 PS". BMW Group archives. BMW Group. Retrieved 31 December 2020.
- Rapp. "Zwölfzylinder Rapp - Flugmotor, 300 PS". BMW Group archives. BMW Group. Retrieved 31 December 2020.
- Rapp. "Flugmotorenprüfstände der Rapp Motoren-Werke". BMW Group archives. BMW Group. Retrieved 31 December 2020.
External links
- Rapp engines including the 200 hp V-8, 300 hp V-12, and the 125/145 hp Rp II V-8 displayed on a test stand, with noticeable variations in propeller dimensions: FF-3380-44 (BMW Group archives)
- The Rapp 300 hp V-12 model featuring inward-directed exhaust ports and equipped with Pallas carburettors: FF-3380-41 FF-3380-42 (BMW Group archives)