Machines that produce thrust can be used to explain how nature of forces which propel a moving machine does it towards a direction of motion. When this process occurs, engines produce a thrust motion of force. Thrust in most cases occurs where there is drag which is a force occurring in opposite direction. Drag is as a result of friction which can also be caused by the difference in air pressure, (Halliwell, 2001).
To understand the dilemma between performance verses efficiency, it is crucial that one understands what both terms relate to, (Mohan, 2014). Performance is as a result of thrust force produced mostly by aircraft engines to overcome drag force. Thrust engines have to do their best to overcome drag force. Efficient performance of thrust engines is attained through that an aircraft has a flat thrust which can be acquired without the need for high power settings.
Efficiency in thrust machines can be supported by the first law of thermodynamics which states that cost needed to generate propulsion. In this case, efficiency means doing a lot of work with little energy. By maintaining a high efficiency in thrust engines, there will be a higher production rate. This can be expressed by the following equation.
Where is the rate of energy needed to create thrust? Note that high η0 indicates low energy input for any work output. The 1st Law of Thermodynamics illustrates that maximum overall efficiency is η0 = 1.
An increase in performance of engine results to an increase in the engine efficiency. This, therefore, means that efficiency is directly proportional to the efficiency of the engine. It is also true that different designs of an engine could result in differences in performance and efficiency, (Senft, 2007). It is however also correct to say that thrust engines that handle low input in a short period will have low rates of efficiency and performance. This translates to the importance of having well-designed machines that give high performance and efficiency within the shortest time possible.
- Dole, C. E., Lewis Jr, J. E., Badick, J. R., & Johnson, B. A. (2016). Flight theory and aerodynamics: a practical guide for operational safety. John Wiley & Sons.
- Halliwell, I. (2001). Exoskeletal engine concept (1st ed.). [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center.
- Mohan, S. (2014). Apache Solr High Performance (1st ed.). Birmingham: Packt Publishing.
- Santoro, R. & Pal, S. (2003). Thrust augmentation measurements using a pulse detonation engine ejector (1st ed.). [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center.
- Senft, J. (2007). Mechanical efficiency of heat engines (1st ed.). Cambridge: Cambridge University Press.