Engine in operation usually ， is fuel is atomized through the nozzle into a mist injected ， to allow it to fully mix with air, thus achieving better combustion efficiency. The quality of the atomized fuel and air mixture plays an important role in power, economy and emissions. However, heavy oils such as diesel ， due to its viscosity is relatively high, at low temperatures poor fluidity. In this case, atomization effect heavy oil is worse than gasoline, this will affect combustion 的 effect, and even even the engine is difficult to start. Therefore, achieving reliable atomization and efficient combustion organization of heavy oil has become one of the core technologies of aviation heavy oil piston aircraft.

There are several ways to improve the atomization and combustion of heavy oil in piston aircraft. The carburetor is gradually replaced by auxiliary preheating: Two-stroke piston engines mostly use carburetors for fuel supply, but it is difficult to ensure reliable atomization and reasonable combustion of heavy oil using existing carburetors directly. Therefore, we can change the design of the intake system, carburetor and ignition system, at the same time add an auxiliary starting preheating system, further improve fuel fluidity. In this improved method, the German heavy oil engine scheme is typical, the intake system uses an acceleration tube; the pump membrane carburetor is improved, and the working mode is close to the mechanical injection system; crankcase preheating; compression ratio reduction; starting to add glow plugs; ignition system changes, energy increase. The disadvantage of this method is that there are many additional accessories, complex design modifications, and difficult implementation. Mechanical injection system: That is, abandoning the carburetor mode, the fuel supply mode is directly driven by the mechanical mechanism attached to the engine to complete the in-cylinder fuel direct injection and flow regulation function. Electronic fuel injection system: Students familiar with automobiles are very familiar with this term. Yes, it is to learn from the electronic injection technology in the automotive industry to improve the design of aviation piston aircraft. The electronic injection has a large adjustment range, and the control freedom and flexibility are higher than mechanical injection.

Thanks to the development of automotive technology, a large number of small high-speed exhaust turbochargers have emerged. Turbocharging technology has also been applied in four-stroke aviation piston aircraft, and single-stage supercharging technology has become quite mature. The use of turbocharging technology increases the engine's output power and achieves power recovery at high altitudes, which can significantly improve the flight speed and service ceiling of unmanned aerial vehicles. Studies have shown that single-stage supercharged piston aircraft can maintain maximum power in 5000 meters of air, but 8000 above meters of altitude, the intake demand cannot be met, resulting in insufficient power output or even stalling. Two-stage supercharging can increase this altitude to 11000 meters. However, at the end of the supercharged compression, the concentration and temperature of the gasoline mixture increase significantly, and detonation is easy to occur. At the same time, the speed range of the gasoline engine is relatively wide, and it is difficult to match with the supercharger, so it is still difficult to achieve high-efficiency supercharging.