The Rapp 200 hp was a water-cooled 90° V-8 aircraft engine built by Rapp Motorenwerke.
The Rapp 200 hp V-8 engine design was derived from the earlier four-cylinder Rapp 100 hp design approximately around 1915.[1] It had eight cylinders with the same bore and stroke of as the Rapp 100 hp, arranged in two rows of four.[2] [3] The engine was said to produce about at 1,350 rpm, while weighing about .[2] [4] [5]
The design of the cylinders and the valvetrain also reflected the design of the Rapp 100 hp four-cylinder.[3] [1] The cylinders of each cylinder row were again arranged in pairs composed of two separate forged steel cylinder liners screwed into the pairwise cast cylinder heads.The cylinder heads had integral cooling jackets and were cast from steel in pairs and then machined.[3]
The valve seats, with the exhaust valve seats being water-cooled, were separately built parts which were screwed into the cylinder heads and could be easily removed for maintenance work.[3] [1] Both inlet valves of the cylinder pair, and likewise so both exhaust valves on the other side, were pressed into their seat by a single pivoted leaf spring.The intake was oriented to inner side of the Vee and the exhaust was oriented to the outer side.
Each cylinder's exhaust and inlet valves were actuated successively from a single cam lobe on the overhead camshaft via roller tappets and rocker arms.[3] [6] The camshaft of each cylinder row was driven via a vertical timing shaft and bevel gears between the two cylinder pairs.Two magnetos were also driven from the vertical timing shaft and were located between the two cylinder rows.[3] [1]
The crankcase was cast from aluminum in two pieces, parted at the center line in an upper and a lower part.It was designed in the same manner as the Rapp 100 hp four cylinder and the 150 hp Rapp Rp III six-cylinder engines.The crankshaft was supported by the main journals in the upper part of the crankcase.[7] Lubrication was done by a gear pump which was mounted on the lowest point of the engine.[3] The gear pump fed the oil from two cylindrical oil reservoirs, mounted front and aft below the engine crankcase, to the main journals of the crankshaft.In order to circulate the engine coolant separate geared water pumps were installed on the respective side of the crankcase for each cylinder row.[3] [1]
The engine had two Zenith-type[7] carburettors, of which each fed one row of four cylinders separately.It appears that different arrangements for the two carburettors have been tried.Some of the engines had the carburettors located at the back end of the engines,[3] while others had them located between the cylinder rows.[1] Also preheated air could be provided to the carburettors via intake air pipes routed through the exhaust.[3]
The same engine design was also implemented as 60° V-12 engine.[8] The Rapp 300 hp V-12 was said to produce around at about 1,350-1,400 rpm, while weighing about .[5] It appears that different variants with outward-facing[9] and inward-facing[8] exhausts have been tried, the latter variant also depicted with Pallas carburettors.