Tungsten Alloy – Excellent Material for Aircraft Counterweights

When an aircraft is flying, its balance will affect the controllability, performance and safety of the aircraft. It is important to maintain a stable center of gravity for optimal control and compliance with flight safety standards. It is important to distribute the weight to allow the aircraft to be balance after considering the weight of onboard equipment, passengers and fuel. In order to achieve this process, it is necessary to temporarily or permanently install the counterweight.

Aircraft load balancing is the key to ensuring flight safety. Selecting and optimizing the aircraft's counterweight can make full use of the aircraft's payload, save fuel and improve air transportation efficiency. The tungsten alloy is small in volume, high in density, these dimensionally accurate tungsten counterweights are nearly the best material for eliminating vibrations in the aircraft. It is available for all types of aircrafts, including commercial and military aircraft.

Although the early aircraft counterweights were typically made of lead, tungsten alloy had became more popular in recent years due to its higher bulk density. This refractory metal has a density of 18.75 g/m3 and is about 50-60% heavier than lead. At the same weight, A tungsten alloy counterweight is only 60% of the size of the one made of metal lead. This means that the volume of the ballast component can be reduced by 40%. Due to the limited space available in the aircraft, compact and dense ballast types are favored in the aerospace industry. Tungsten alloys have a high density and a small volume, which expands the possibility of distribution within the aircraft, especially in the tail or nose regions of a space where space is limited.

In addition, tungsten alloy does not only has the advantages of high density, but also has the advantages of high strength and hardness, good thermal conductivity and solderability, good oxidation resistance and small thermal expansion coefficient. It can also be used for aircraft load simulation during flight test. So as to etermine the exact position of the ballast under different payload conditions. In any case, tungsten alloys are currently the most effective material for balancing the overall weight of the aircraft. Balanced weight components made of tungsten are more easily compliant with the AS9100 standard (AS9100 is an internationally recognized quality standard established by the aerospace industry).

The tungsten alloy is classified into W-Ni-Fe, W-Ni-Cu, W-WC-Cu, W-Ag, etc. according to the alloy composition characteristics and use, and its density is between 16.5-19.0 g/cm3. Since it is necessary to mix copper and nickel metal which are easy to change in price, the production of high specific gravity alloys generally adopts powder metallurgy method, and such processes generally require a degree of sintering. Although the technology now also has 3D printing technology to achieve the manufacture of tungsten alloys. However, tungsten is a refractory metal with a high melting point, so high specific gravity alloys are still commonly produced by conventional methods. The conventional method of sintering a high specific gravity alloy is a hydrogen reduction sintering method in which a compact is placed in a graphite boat or a molybdenum boat and sintered under hydrogen protection. In addition, there are vacuum sintering method + isostatic pressing combined process, sintering-hot isostatic pressing process and so on.

Aircraft counterweights are classified as temporary counterweight and permanent counterweight. Temporary counterweights are generally bolted to the structure of the aircraft and can be added and removed as needed. It is marked for their purpose and total weight. Once the temporary ballast is removed, the weight and balance of the aircraft must be checked again. If it is a permanent counterweight, it must be fixed and labeled to avoid accidental removal from the aircraft.

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