Rotary engine

Of the rotary motor is usually an internal combustion engine, wherein the crankcase and the cylinder rotating around the crankshaft. The cylinders are mounted on many models of a star around the crankshaft, but also Boxer and cylinder assemblies were constructed. The movement of rotary engines is kinematically reversed compared to conventional piston engines. Most models of rotary engines had a fixed crankshaft with attached rotatably mounted connecting rods and a rotating crank with cylinders. This cylinder and crank pin are arranged eccentric to each other, whereby the hub of the individual pistons within the cylinders is about. Some late models the crankshaft rotated in opposite directions to the cylinder star to reduce the absolute speed of the cylinder star.

The kinematic reversal of the rotary engine can be found in a similar manner, the rotary engine, which was built both as a rotary engine as well as a rotary engine.

A further variant of a rotary motor is the elbow engine, a combustion engine, which converts pressure steam or compressed air into mechanical energy.

Overview and History

Rotary engines were mainly used in the early days of aviation. Since it was on the lookout for powerful, yet lightweight engines, they wanted to replace the complex and heavy water cooling by the simple air cooling. In order to obtain a sufficient air flow for cooling and save the flywheel was allowed to rotate the cylinder about the crank shaft. Rotary engines had up to 14 cylinders, these variants were not widely prevalent, with its double cylinder radial due to cooling problems. In addition, because of the high rotating masses were large moments of inertia, which affected the maneuverability of the machines.

The rotary engine was invented in Gennevilliers (France) in 1908 by the brothers Laurent and Louis Seguin. Your engine was known as the " Gnôme ". In the German Empire from 1913 built the engine Oberursel construction licenses under the name Oberursel- Gnôme U O ( 7 cylinder, Displacement 11.8 L; 60 kW/80 hp at 1200 rpm ). Meanwhile, further, the radial engine U III of 1914/15 with 14 cylinders and 115 kW/160 hp was not convincing in practical use, because it showed the above-mentioned problems.

After Oberursel U I (9 cylinder; Displacement 16.3 L; 70 kW/95 PS) ( Displacement 15.1 L; 9 cylinder 90 kW/120 PS) at the end of 1916 in the construction of the Le Rhône UR IIa in several fighter aircraft ( Fokker Dr.I, Pfalz Dr.I ) used the air force of the German army. As a final Oberursel development was in April 1917, the UR IIIa acceptance testing of the army. This engine with 11 cylinders and a displacement of 18.4 l made ​​88 kW/120 hp.

The Gandenberger'sche Maschinenfabrik Georg Goebel in Darmstadt was able to achieve the final building inspection for their rotary engine Goe II in early 1917 after three years of development time. The construction with 7 cylinders, 15.7 liters and 75 kW/100 hp of power was only built in small numbers and replaced from May 1918 by Goe III, who with 9 cylinders and a displacement of 27 liters, a power output of 118 kW/160 PS had. Most of the 229 delivered Goe III used in the Fokker Jagdeinsitzern.

Advantages and Disadvantages

Rotary engines do not require any additional masses, since the crankcase and the attached cylinders act as a flywheel. This made them lighter than conventional ( series ) engines with mechanically quiet operation by about a third. The weight advantage was especially for use in fighter aircraft of the First World War, a crucial factor.

The disadvantages that led to the extinction of the engine type, different properties are given:

• The gyroscopic moment affects the maneuverability of aircraft and since the first airplanes were relatively easy, it is seen during rapid flight maneuvers as a circumstance of crashes.
• Very high need for lubrication, because the Coriolis forces in the rotating motor high lateral forces exercise (sometimes higher than the longitudinal force in the piston ) on the cylinder walls. Due to the rotation much oil has been pressed and ejected into the cylinder, which was the cause of the high demand for lubricants. The first test engines consumed in some cases even more oil than gasoline, with "modern" rotary engines of consumption still kWh was 250 g / (equivalent to fuel consumption of a current diesel engine).
• The loads due to Coriolis forces led to a high degree of maintenance.
• Windage loss by the rotating housing ( 10 to 15 %).
• Power limitation of poor volumetric efficiency, because the mixture is passed through the crankshaft, which results in adverse current conditions, and it heats up in the crankcase ( in turn cools the motor). Wherein overhead feed mixture addition, the centrifugal force causes a pressure loss during suction of the fresh gas into the cylinders.

On the other hand, there were also advantages such as:

• Especially in the gyroscopic moments fighter aircraft support especially the rapid flight maneuvers, but with a preferential direction
• When used for example in automobiles were rotary engines even without wind or blower is sufficient air cooling.
• The internal cooling of the motor is supported by the feed mixture.

Later models had separated from the crankcase mixture feeding because of the heating. Some patterns drawn on the fresh gas via flutter valves, resulting in throttling to violent flash backs, which is why rotary engines were often controlled by switching off and on the ignition. If at air shows replicas of old aircraft einschweben with these engines for landing, can be heard clearly the switching off and on the ignition to decrease speed.

Since the fuel-air mixture was passed through the crankcase, there was a danger of oil dilution by fuel lubrication problems associated with, and therefore preferably the benzinunlösliche castor oil was used. The rotation of the cylinder occurred on the pistons also Coriolis forces, which had the side and had a high level of maintenance result.

Some late model (eg the Siemens & Halske Sh.III 1917 ) was designed as a counter- rotors in which the crankshaft is turned in opposite directions through a gearbox to the cylinder star. At a 1:1 ratio by the speed of the cylinder star opposite the plane could be halved at the same relative velocity between the star and the crankshaft and thus the same power. The propeller efficiency was significantly increased while reducing the negative effects of rotation as the centrifugal effects and pumping losses.

Use in vehicles

Motorcycles

Already in 1892 there was a French motorcycle from Millet with rotary engine. In the 1920s there was the Megola, a motorcycle with a five-cylinder radial engine revolution counter in the front hub, the housing ( outstanding part between the spokes ) rotates together with the wheel, and its crankshaft in the opposite direction. The Megola had neither manual nor clutch was sporting a very successful and in 1924 against the BMW factory team German masters.

There were also outstanding radial engines in the motorcycle frame, best known and most commercially successful was the Redrup radial of 1912 with a counter- circulation three-cylinder and in contrast to an otherwise Megola conventional powertrain with external gearbox and belt drive.

Some of 1904 in Wales built by Barry motorcycles even a rotary engine was installed, but no ( Shaking with only two cylinders like a V- motor) radial engine but a two -cylinder boxer engine, which rotated in the center of the frame.

In the 1940s Cyril Pullin constructed even a single-cylinder engine, whose housing was rotating in the wheel hub along with the wheel. Clutch and drum brakes were installed in the Power Wheel hub called as weight compensation. However, the Power Wheel was still at the prototype stage addition.

Automobile

Even in automobiles American automobile brands beginning of the 20th century, there were rotary engines. However, the manufacturer Adams - Farwell, Balzer, Bailey and Intrepid had only regional distribution.

Aircraft

In aircraft rotary engines were mainly in the period before and during the First World War for use, such as in the Fokker models E1 -E3 and Dr.I. In the UK, came the most successful rotary engine by Walter Owen Bentley.