Very High Bypass Aircraft Engine

I would like to simplify the “Hybrid Turbofan Engine” I proposed earlier. My latest proposal simplifies the design and reduces the overall weight of the engine. Allowing easy rotation of the engine for vertical takeoff and landing (VTOL).

The frequent launches of space rockets resulted in mass production of high efficiency rocket engines. These engines burn pure fuel and oxygen quite efficiently compared to a typical turbofan engine that burn a jet fuel with the available ambient oxygen.

The engine I propose would have a ducted housing like all turbofan engines. Instead of a fan, there would be a big propeller in the front. It would be powered by a turbo engine, similar to the turbopumps of the rocket engine. Compared to a fan, the propeller would induce less drag and allow more air flow efficiently. Behind the propeller there would be a rocket engine with pre-burners for liquid methane and LOX. The engine would not have a nozzle. Instead, the by-passing air from the propeller would be heated to generate thrust. The bypass ratio would be higher than a typical turbofan engine. The cooling of the rocket thrust chamber would be done by the bypassing air. High amount of air bypassing the engine would result cooler exhaust gas. Additionally, the duct casing of the engine would not heat up, hence can be made of light weight composite materials.

Even though the rocket engine and the turbo prop would consume liquid oxygen, which is not the case with traditional turbofans, the very high bypass ratio of the engine would increase the efficiency of the engine. Additionally, it would make the engine performance independent of the ambient oxygen level. The turbo prop and the rocket engine would be independently controllable unlike a turbofan where the duct fan and the compressor engine are connected with a shaft. My design allows lighter and higher thrust engines to be manufactured using the current technologies. Whereas the turbofan engines are hard scale up after a certain point.

The thrust of the engine would come from low-speed large amounts of air instead of high-speed small amounts of air. This is important for a VTOL. I propose this engine to be used on VTOL construction drones. In such a use case, hot exhaust gases would melt the surrounding area.