At this Singapore Air Show, the Singapore Air Force, as the host unit, naturally brought almost all its belongings, including F-15SGF-16D/D+, A330MRTT, AH-64D, CH-47F, H225M, etc. Among them, the "old and useful guy" "Chinook" stood in the outdoor static display area and looked particularly energetic, and visitors can also board its cargo hold to experience it firsthand, which is an excellent experience.
The unique "Chinook"
The CH-47 Chinook is the most well-known and most produced medium and large helicopter in the world. It is also the largest helicopter of the US Army today, and there is no clear replacement model yet. The CH-47 was first developed in the 1950s. It adopted a tandem twin-rotor layout that was relatively new at the time and is not common today. The two tandem rotors of the CH-47 are placed above the fuselage, and the two engines are externally located at the rear of the fuselage. The engines drive the front rotor through a transmission shaft installed on the top of the fuselage.
This design means that the CH-47’s cabin and external attachment points are not affected by the fuselage structure. The cabin is long and straight, and the three external attachment points are easy to arrange. Its cargo hold can carry 33-35 fully armed soldiers, or 10 tons of cargo, or a 155mm howitzer, or a small car. The external attachment points also have corresponding carrying capacity. This spacious and convenient cabin and external attachment point design is due to the tandem twin-rotor layout. There is a foldable springboard cabin door at the tail of the CH-47, which makes loading cargo very easy . Small vehicles can freely enter and exit the cabin through this door. There are also two large side doors on the aircraft. Due to its large load capacity, the CH-47 can be regarded as an ideal battlefield supply helicopter.
Another advantage of the tandem twin rotors is that it does not require a tail rotor to balance the torque of the rotors like other helicopters, and has high power efficiency. But there are also some disadvantages, such as the two rotors must be synchronized to avoid collisions with each other. And because the CH-47 is large in size, plus two rotors with a wingspan of 20 meters, the range affected by the entire aircraft during takeoff and landing is 100 meters. The biggest disadvantage is that due to the overlapping of the rotors, the airflow generated interferes with each other, resulting in a large power loss. Therefore, only a few helicopters have adopted this layout so far.
Since the 1950s, Since the 1950s, CH-47 has developed a variety of improved models, and it is still the only heavy transport helicopter of the US Army. The latest model is CH-47F. The US Army plans to improve it and plan to serve until 2060. The transport aircraft has been sold to 16 countries, including Singapore.
Singapore’s CH-47F
Singapore’s CH-47 was purchased in 1996. The earliest CH-47 equipped was the D model, which was replaced with a stronger engine. The load capacity is excellent, with an external load of up to 12 tons and a load capacity of Trucks and various types of howitzers can be hoisted. In 1999, 10 CH47-SD models were purchased. By 2016, Singapore plans to purchase 10 new CH-47Fs to replace the earliest CH-47D model. At the same time, the CH-47SD will be further upgraded to meet the standards of the CH-47F. Not only that, Singapore will continue to purchase more CH-47Fs to further increase the total number of CH-47Fs in service. The CH-47F model is developed based on the CH-47D model. The main improvements include: the adoption of a new one-piece body structure to reduce the impact of vibration and reduce the need for logistics maintenance: the structure of the cockpit, cabin, rear section of the body, pylons, and ramp doors has also been strengthened; in addition, new engines, avionics systems, and improved communication systems have been installed. The CH-47F helicopter is mainly responsible for air transport missions. It can be used to transport troops, supplies, equipment, or assist in the deployment of artillery positions. It can also be used for medical evacuation, search and rescue, aircraft recovery, personnel parachuting, disaster relief and other tasks.
The CH-47F has an empty weight of 11,148.6 kg. The two three-blade main rotors arranged in a front and rear longitudinal arrangement are made of composite materials. The two front landing gears are double-wheeled and the two rear landing gears are single-wheeled. Self-sealing fuel tanks are installed on the outer sides of the fuselage, and three additional fuel tanks can be installed in the cabin to further extend the range. The crew of the CH-47F includes the pilot, co-pilot and flight engineer. The aircraft is equipped with two T55-GA-714A turboshaft engines, equipped with Goodyear’s digital engine control system (FADEC). Each engine has an output power of 4,733 shaft horsepower, a maximum flight speed of 302 kilometers per hour, and an effective range of 609 kilometers. The two-seat cockpit uses a digital glass cockpit equipped with Collins’s Common Avionics Architecture System (CAAS), including 5 color multi-function LCD displays, and is equipped with BAE Systems’ digital advanced flight control system and data transmission system. The CH-47F’s digital cockpit integrates flight, mission management, communication, navigation and other functions, which will enhance situational awareness and battlefield survivability.
In addition to the common missile warning system (CMWS), improved anti-guided ejection system and other electronic warfare and self-defense systems, the CH47F can be equipped with up to three 7.62mm machine guns or 7.62mm six-barrel rotary machine guns. The cabin is equipped with AAR’s new cargo loading system, which can directly load two Hummers, or one Hummer and a 105mm howitzer. Previously, it could carry up to 36 people, but after the improvement, it can carry up to 24 stretchers and related medical staff. The external hanging weight of the aircraft is 12,700 kg, and the belly is equipped with three external hanging hooks.
Currently, the latest CH-47F developed by the United States is Block II, with an empty weight of 12,156.5 kg and a maximum take-off weight increased to 24,500 kg. The structure of the fuselage has been improved, and a new advanced Chinook rotor (ACRB) has been installed. The tip of the rotor blade is swept back, which can increase the load capacity by 680 kg. The T55-715 engine with a 20% increase in power has been installed, and the power of a single engine has been increased to 6,500 shaft horsepower. It is also equipped with an active control system (APAS) to improve the efficiency of the advanced digital flight control system. In addition, the transmission system has also been updated to increase torque by 9%. The redesigned fuel system not only reduces the total weight, but also increases the fuel volume and extends the range.
The CH-47F BlockⅡ, which will enter the initial small-scale production stage in 2021, will provide better support for the US Army’s rapid response capabilities. According to the latest contract, Boeing plans to first refurbish and manufacture three CH-47Fs into engineering manufacturing development aircraft, and the first CH-47F BlockⅡ is expected to be delivered in 2023. However, the US Army decided in mid-2019 to postpone the CH-47FBlock program for five years in order to reserve the budget for the "Future Vertical Take-off and Landing Program" (FVL), so future developments remain to be seen. In addition, the US Army also plans to have Boeing develop the CH-47F Blockm model after 2025. In addition to lengthening the fuselage, it will also be equipped with a 6,000 shaft horsepower engine. The new engine is being developed under the "Future Affordable Turbine Engine Program" (FATE). If all research and development goes smoothly and the improved performance meets the needs, the US Army’s CH-47 helicopters will continue to serve until 2060.
The reason why the United States has been postponing the replacement plan for helicopters is that the CH-47F is good enough to use, and in the process of improvement in the United States, the two can no longer be regarded as the same aircraft. The F and the early A type are almost equivalent to a generation change. Because of this, the seemingly old CH-47F is not actually old, which is also the key to Singapore’s purchase of the CH-47F. At present, many countries are using the CH-47F. As Boeing’s key model, there will naturally be no less improvements in all aspects. Therefore, not only the United States, but also these countries that have newly purchased the CH-47 or are in good condition, the CH-47 will be guaranteed to serve until 2040, and it is likely to be in service after 2050.
In addition to the United States and Singapore, the United Kingdom, Spain, Australia, South Korea and other countries have also purchased CH-47F helicopters. Germany announced in June 2022 that the "Next Generation Heavy Helicopter Program" (STH) will purchase 60 CH-47Fs. In March 2010, Australia purchased 7 CH-47Fs to replace the CH-47Ds in service. All of them were delivered in 2017 and assigned to the 5th Aviation Regiment. In April 2021, the United States announced that it agreed to Australia’s purchase of 4 more CH-47Fs.
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