When a pilot operates an aircraft, the weight on board and the force of gravity affect its safety, handling and performance. It is crucial to maintain a stable center of gravity at all times for optimal control and compliance with flight safety standards.
After taking into consideration the essential onboard equipment, fuel and passengers, it may be important to add or distribute more weight such that the aircraft is brought within the allowable weight range. In order to aid this process, ballast can be temporarily or permanently installed. Metal ballast is generally used in all types of aircraft, including commercial and military operations.
Why are Tungsten Heavy Alloys Used in Aerospace Ballast?
While ballast is usually made of lead, tungsten alloys have become more popular than lead in recent years because of its higher density at lower volume. This refractory metal has a density between 16.8 g and 18.75 g per m3, about 50-60% heavier than lead.
The resulting component is only about 60% of the size of the corresponding lead component at the same weight. This means ballast components can be 40% smaller, which extends the possibilities for distribution within the aircraft, particularly in the tail or nose areas of the plane where there is limited space.
In addition, tungsten alloys are employed in the simulation of aircraft loading during flight tests so as to establish the precise locations for ballast to be situated under varying payload conditions. At any rate, tungsten heavy alloys can reduce the overall weight of the aircraft. It is important that ballast components conform to AS9100, an internationally recognized quality standard set out by the aerospace industry.
Center of Gravity
The center of gravity (CG) is the point at which the weight is concentrated, and it needs to be shifted to within an optimal range before the aircraft is operated by the pilot. The allowable weight range for each individual aircraft is determined by the manufacturer. The aim is to balance the weight suitably such that the plane is neither tail-heavy nor nose-heavy.
There are different types of weight that influence the center of gravity including the onboard equipment, structural weight of the aircraft, air crew, passengers, cargo and fuel.
Adding Ballast to the Balance
If more weight has to be added to maintain a permissible center of gravity, ballast will be added, often as far forward as possible (or as far aft) to lower the amount of total weight required. Since only limited space is available in aircrafts, compact yet dense types of ballast are favored in the aerospace industry. As tungsten alloy has high density and small volume, it is believed to be the most suitable material for aircraft ballast.
Permanent ballast adds to the aircraft’s null weight, since they are often bolted to structure. Lead plates or bars are commonly used for this purpose. Permanent ballast must be secured and labeled accordingly so as to avoid accidental removal from the aircraft.
Temporary ballast can be added and removed as required, and is hence labeled with its purpose and total weight. Once removed, the weight and balance of the aircraft must be checked again.
Where to Find Tungsten?
Customers interested in tungsten can visit the Matmatch website to find out more about the characteristics, properties and chemical composition of this metal.
Matmatch collaborates with several leading tungsten suppliers, which can be found on the company’s suppliers page. From Matmatch, customers can get the latest information on engineering materials and can directly contact suppliers, without a middleman.
This information has been sourced, reviewed and adapted from materials provided by Matmatch.
For more information on this source, please visit Matmatch.