In the recent Sino-foreign joint exercises, our military actually began to try out a small domestically produced unmanned aerial vehicle (UAV) that is "not well known" but can airdrop six grenades at a time, and has also taken it out of the country for use by foreign militaries. This drone is different from our common multi-rotor drone, but uses a coaxial double-propeller aerodynamic layout, which looks small, but can carry 6 grenades, which can be said to be very fierce.
This raises the question: why would the Chinese military install a coaxial double propeller mini bomber? What are the advantages over our common multi-rotor drones?
This controversy has actually existed in the history of helicopter development, Russia's Ka-52 series is considered to be the representative of coaxial double propeller helicopters, but the US military still chose the single propeller scheme, the controversy is that the advantages and disadvantages of coaxial double propeller use in helicopters coexist. Coaxial twin propellers use two propellers of the same diameter coaxial arrangement on the helicopter, eliminating the tail rotor and using two sets of rotors to rotate in opposite directions to provide lift and maintain a stable attitude in the air. Because there is no tail rotor, the coaxial twin-rotor helicopter has a higher hovering efficiency, which is 17%~30% higher according to Russia statistics. The second advantage of the coaxial twin-rotor helicopter is that it is relatively short, and the longitudinal size is only about 60% of that of a single-rotor helicopter. Due to the concentration of structural weight and load, this helicopter also has good acceleration performance and outstanding high-speed flight characteristics.
However, the reason why the United States does not use this method is that the coaxial helicopter has a series of problems such as complex mechanical structure, hidden dangers of paddle when high maneuvering, higher fuselage and expensive cost.
So, why did the Chinese army's special operations squad choose a coaxial twin scull mini bomber? The most important reason is that the UAVs that China is now equipped with are controlled by motors, which fundamentally solves all the shortcomings of the complex structure, high cost and hidden dangers of the coaxial double propeller aircraft. At the same time, it also has a series of advantages such as small size, easy to carry, strong load capacity, flexible use, good silent performance and low cost. Whether it is compared with a large Chada integrated UAV or a cheap multi-rotor UAV, the advantages of the coaxial double propeller UAV are as follows:
1. Strong vertical take-off and landing capability, in the case of the same size, the coaxial double propeller UAV has higher flight efficiency and larger payload, and has excellent load capacity and endurance. It stands to reason that it is impossible for such a large UAV, with 6 grenades on it, to be able to perform long-term cruising missions, but it is possible to use the coaxial double scull scheme.
Second, it is possible to achieve high-precision balance control and maintain stability in various flight conditions. The electric drive solution allows for better precise control of the propellers, which can fly at high speeds and are quite capable of adapting to high winds.
3. Low noise and energy saving, when the payload is the same, the rotor speed of the coaxial double propeller UAV is lower, the noise is smaller, and it is more difficult to be detected. Its pitch and roll control does not require the acceleration or deceleration of the main rotor, so it is more energy efficient.
Overall, the rise of China's unmanned combat forces, the aerodynamic layout of the coaxial sculls will surely shine because of its natural advantages. In the future, relevant manufacturers can launch larger coaxial double-propelled UAVs for a series of combat missions such as reconnaissance, strike, and fire strike effect evaluation with ground armored forces. Compared with multi-rotor UAVs, this UAV has an important disadvantage that the cost may be more expensive, but as long as the scale of the equipment is large enough, its cost-effectiveness ratio is still very attractive. The route of China's drone technology needs to blossom in order to promote the PLA's combat to make great strides in the direction of unmanned.