5. Power Transmission.—The rotor transmits its power to the cams mounted on the drive shaft. However, an alternate method of power transmission is available and is shown on the accompanying drawing. In this arrangement, while the cam and cam followers are in continuous contact, they are relieved from peak pressure during the power stroke by means of a sectional internal gear and pinion drive! The tooth engagement is mechanically controlled by the drive.

6. Construction.-In the design of this rotary engine, the overall weight was not a factor since the engine is already fifty percent lighter than its conventional counterpart. The engine block and end plates can be made of ASA alloy cast iron. Rotors and pistons should be of light weight aluminum alloy so as to reduce the inertia forces of the intermittent motion. It will be noted on the drawing that the aluminum rotors are provided with a cast iron cylinder liner, so that wear is uniform with the engine block.

The conjecture has been raised that curved pistons, not presently used in machines, would be difficult to manufacture. Actually, the opposite holds true. The pistons can be manufactured in any machine shop, using a simple procedure. Six pistons are cast together in the shape of a large "doughnut." The casting contains a hollow cavity for each piston. The sand cores which form these cavities are held in casting position by a sand core extension through the large piston opening. The whole "doughnut" is then fastened to a lathe, where first one half of the surface is machined with a concave form-tool. Then the "doughnut" is reversed on the lathe and the form-tool machines the other half. The pistons are then sawed off. Next, each piston is fastened to the lathe with a jig, for facing and cutting grooves for the piston rings. The toroidal chamber can be machined on the lathe in the same manner, using a convex form-tool.

7. Engine Cooling.-The engine block can be provided with a series of fins for air cooling instead of the jacked for liquid cooling, shown on the drawing. Pistons and rotors are oil cooled as described above, paragraph 3 of this chapter. Actually, the cooling requirements are moderate: there is less heat loss in the Tschudi Rotary Combustion Engine because of its unique thermodynamic properties.

V. THERMODYNAMIC FEATURES OF THE ROTARY ENGINE

1. Idealized Complete Expansion Cycle.-This revolutionary engine is bound to win universal acceptance even if it were judged solely on its mechanical characteristics. But there is a bonus: its unique design permits this engine to be operated close to the idealized complete expansion cycle which results in a higher thermal efficiency, more complete combustion of gases, and a cleaner and quieter exhaust.

The Complete Expansion Cycle is a variation of the Otto Cycle, but without the normal waste of energy during the expansion process. By making the expansion stroke much longer than the compression stroke, expansion is permitted to continue to atmospheric pressure, thereby increasing thermal efficiency by producing more work from the same fuel input. While the reciprocating engine could be

adapted to perform as a complete expansion engine, the inordinate size of the resultant engine and the additional friction loss from increased piston travel would more than offset the gain in thermal efficiency. However, with the Rotary Engine, it is simply a matter of locating the intake and exhaust ports somewhat advanced on the toroidal track, in the direction of the piston travel. With its unique and its friction-free pistons, the Tschudi Rotary Combustion Engine is ideally suited to reap all of the benefits of the Complete Expansion Cycle.

2. Complete Combustion.-Considering the critical condition of our environment, perhaps the most important advantage of utilizing the Complete Expansion Cycle is that it will reduce air pollution at its source. By permitting nearly complete combustion of the gaseous fuel, the emission of unburned hydrocarbons will be virtually eliminated. Also, engine noise will be abated by avoiding violent blowdown of gases inherent in the reciprocating enigne.

3. Scavenging.—Scavenging is not required for the operation of this rotary engine, but its inclusion is quite simple and advantageous. Only a minute quantity of fresh air is needed to expel the remnants, while the combustion chamber, now in its smallest volume, travels from the exhaust port to the intake station. 4. Cool Inlet Region.-A large, continuous cool intake port insures an adequate induction of air and a high volumetric efficiency. The weight of the charge is greater, engine knock less.

VI. DEVELOPMENT TO DATE

The Tschudi Rotary Combustion Engine is the result of years of study and research, as documented by several U.S. patents that have been granted on the invention. A full size proto-type engine has been built to check out the mechanical and thermodynamic function. Acknowledgment is due to the Blair Tool and Machine Corp. of College Point, New York: the management who consented to enter this order for a machine with "curved pistons", their skilled machinists who precision built the engine and made it run. The experience gained with this prototype resulted in a new, comprehensive U.S. patent Application which has been granted as U.S. Patent No. 3,381,669, issued May 7, 1968.

Recently, this engine was the subject of a 45 page thermodynamic study by Mr. J. Vargas, an engineer with experience in internal combustion engine design. Mr. Vargas prepared the study as a partial fulfillment of the requirements for obtaining a Master's Degree at The Cooper Union for the Advancement of Science and Art, New York. In the conclusion of his Thesis, Mr. Vargas writes:

"Thermodynamically, then, the Tschudi Engine appears to be an excellent engine, that can yield a large amount of power at speeds and compression ratios that are below those used in modern engines. The operational advantage of this is clear, and graphically illustrates the potential attractiveness of this engine.

"Adding up the excellent thermal and volumetric efficiencies that can be obtained in this engine results in a thermodynamic behavior far superior to any conventional internal combustion engine."