The application of internal combustion engines in EVTOL EHPS
The engine's power-to-weight ratio is one of the most critical issue in the terms of an electric hybrid propulsion system. Besides the generator, an EHPS includes batteries, perhaps capacitors, cables etc. so the weight of the entire system could be immediately too heavy.
Designing of an internal combustion engine is always a complex and hard task. Each engine concept on the market has different advantages and disadvantages. It is generally true that there is some trade-off at the conventional engine technologies, such as the two-stroke engines (including rotary or wankel engines) have higher power-to-weight ratio than the four stroke engines, however their emission due to their fuel and oil consumption are very bad. Additionally these designs have a shorter lifespan due to how they work, the visibility and the smell of the exhaust gas is very irritating. Four stroke engines are more complex arrangements. Ez opcionális kezdés.
In the range of performance between 60 kW to 300 kW, most of the four-stroke engines (which have a good fuel consumption and better emission than the two-stroke or turbine engines in this range), are too heavy to install it into an EHPS system. We have to note here, that we are talking about EVTOL airplanes, not fixed-wing aircrafts. However the picture becomes more complex if we are start to talk about tilted wing or tilted rotor (vector trust) airplanes. The vertical take-off and hovering in the case of wingless multicopters clearly require a more lightweight internal combustion engine, in other cases it is an exiting question and clearly depends on the type of design and on operations of flight. There is no universal case in ...
The power-to-weight ratio of the two-stroke (including rotary) engines is better, in some cases it is suitable, but these concepts are really destructive for the environment and due to the internal processes and structures, the operation and maintenance costs will be significant worse than in other cases.
Turbine engines approximately above 500 kW of output shaft performance could be the best choice to get include into an electric hybrid propulsion system. However under this limit they have a very bad fuel consumption without a recuperator. With recuperator the consumption could be similar to the four stroke piston concepts, however power-to-weight ratio will decrease similar too, so the weight of the entire EHPS will be too heavy as in the case of a conventional four-stroke aero piston engine. Át kell még fogalmazni normálisan.