Which are two common types of reciprocating engine exhaust systems?

The two common types of reciprocating engine exhaust systems are indeed the short stack and collector system.

The short stack exhaust system typically consists of a simple pipe that directs exhaust gases upward away from the engine, which helps reduce the chances of carbon monoxide accumulation in areas near the aircraft. This design is often used in smaller aircraft where space and weight are at a premium.

On the other hand, the collector system is designed to efficiently combine the exhaust from multiple cylinders into a single pipe or outlet. This design promotes better exhaust flow and can improve engine efficiency and performance, as it minimizes back pressure and optimizes scavenging of the cylinders.

These systems are essential for proper engine operation and the effective management of exhaust gases, directly impacting engine performance and safety. The other options, while they mention different exhaust concepts, do not accurately reference common types of reciprocating engine exhaust systems as used in aviation.