With the rapid development of the eVTOL (electric vertical takeoff and landing aircraft) industry, ducted fans, as a new generation of core propulsion technology, are entering the vision of more and more engineers and companies. Compared to traditional open propellers, ducted fans have several significant advantages: they wrap the blades around an annular fairing, which not only significantly increases low-speed static thrust, but also effectively suppresses blade tip vortices and noise, improving operational safety. They are very suitable for low altitude and complex urban air travel applications. Therefore, ducted fans have become the mainstream solution for many eVTOL machine manufacturers and technical teams to compete for layout. The application of spinning forming technology in the manufacturing of aircraft ducted fans has the following advantages: 1. Overall forming of duct shell The outer casing of the ducted fan is a thin-walled, large opening, and inlet lip shaped rotating body. Traditional methods often use "sheet metal welding" or "composite material winding+splicing", which result in multiple welds and accumulated geometric errors. The use of powerful CNC spinning can achieve "overall forming":
The wall thickness can be continuously reduced within the range of 2-6 mm according to the requirements of equal strength, and the weight is reduced by 15-25% compared to welded structures;
No circumferential weld seam, eliminating the source of weld crack and increasing fatigue life by more than 30%;
The transition between the inlet lip and the straight tube section is achieved through one-time spinning, ensuring a smooth intake profile and reducing intake distortion and noise.
2. Engine inlet lip and intake cone Spinning machine can directly spin aluminum alloy, aluminum lithium alloy or titanium alloy slab into a rotating body with a large curvature inlet lip, with a surface accuracy of ± 0.2 mm and a thickness error of ≤ 0.05 mm, which can meet the strict requirements of high-speed airflow for surface accuracy. 3. High strength aluminum/titanium alloy fan hub The CNC spinning machine has the function of "staggered spinning+synchronous feed", which can complete the transition forming of Ti-6Al-4V fan hub from "thick walled hub to thin-web disk" on the same equipment:
The material streamline is continuously distributed along the contour, which can increase the fatigue limit of the wheel hub by about 15%.
In the future, only precision machining of bearing holes and dynamic balancing are required to reduce weight, resulting in a 40% decrease in machining volume.
4. Acoustic liner and exit diffuser For culvert sections that require composite acoustic micropores or honeycombs on the inner wall, a 1-2 mm thin-walled matrix can be spun out first, and then connected to the honeycomb interlayer through "bonding spot welding" to ensure the strength of the main body and reduce the risk of secondary processing deformation. 5. Lightweight and Cost Benefit Spinning parts can usually reduce the design wall thickness by 10-20% while maintaining the same strength; For the 300-600 mm small ducts widely used on eVTOL, the cost of aluminum alloy spinning shell per piece is 20-30% lower than that of composite winding bonding scheme, and the production cycle is shortened to 15-20 minutes per piece, which is more suitable for mass production. PROSPER has already completed process validation on key rotating parts such as the shell, inlet lip, and fan hub of ducted fans, and has also developed machines suitable for producing such products, which are suitable for mass production of narrow body aircraft APU ducts, urban air transport (UAM) multi duct platforms, and unmanned aerial vehicle thrust vectoring ducts. If you have any related products, please feel free to contact PROSPER.
