Even the Latest Fighter Jets Freeze... Why?

Creating Extreme Environments Before Weapon System Deployment to Evaluate Performance and Lifespan
Must Withstand Various Conditions Including High Temperature, Humidity, Sand, Dust, and Mold

[Korea Defense Science Research Institute Senior Researcher Kwon Hyuk-beom] After returning to work following a long holiday and turning on your PC, you may have experienced a “blue screen” and failure to boot. This phenomenon occurs due to contact faults in the memory section of the PC, where heterogeneous materials with different rates of contraction and expansion are assembled. Modern weapon systems use a large number of electrical and electronic components, and if such a phenomenon occurs during wartime, it could cause tremendous damage to friendly forces. In particular, weapon systems must operate reliably under all circumstances to ensure national defense and the safety of the people.

Especially in South Korea, with the implementation of the military aircraft airworthiness certification system, it is required to verify whether aircraft systems (including aircraft and ground equipment) are designed to operate under natural and induced environmental conditions as part of the design criteria. The verification method requires proving that the equipment performs the required functions and meets performance standards within the natural and induced environmental domains.

▲ What is Environmental Testing? = Environmental testing plays a very important role in the evaluation of developed weapon systems. Most weapon systems have “environmental requirements” documented as high-grade documents from the early stages of development planning, and except in cases where appropriate test equipment is unavailable, most environmental requirements are verified through testing.

Environmental testing involves artificially simulating extreme environments among various environments encountered during the life cycle of a weapon system or civilian product, from development and production to end of life, to evaluate the impact of these environments on the performance, functionality, and lifespan of the target weapon system or product.

In the United States, the importance of environmental testing has been recognized since the Cold War and space race era of the 1950s and 1960s. Significant defense budgets were invested to investigate and research global environments, build testing facilities, and conduct environmental tests. Notably, the McKinley environmental test facility, capable of testing large aircraft such as the C-130 transport plane, was constructed at Eglin Air Force Base, and environmental testing for recently developed aircraft systems like the F-35 has been continuously conducted there.

In South Korea, many environmental tests have been conducted due to the development of the electrical/electronic and automotive industries. In the defense sector, although limited, environmental testing has been continuously performed from the development stage according to the U.S. military standard MIL-STD-810.

In the 21st century, with the increase in large-scale weapon system development and the national push for defense exports, the ADD constructed a large environmental test facility within the aviation test site (August 2008) to conduct environmental testing for many large weapon systems developed domestically by ADD and defense companies. It also actively supports environmental testing for civilian products such as automotive batteries.

▲ Environmental Factors = Weapon systems are affected by natural and induced environmental factors encountered from production at manufacturing plants (location, altitude, etc.), transportation means (ships, aircraft, vehicles, etc.), storage methods, location and operation, usage, and mounting (location, altitude, marine environment, etc.) depending on the platform on which they are installed.

For example, an air-to-ground missile is a guided weapon mounted externally on an aircraft (platform). It is influenced individually or simultaneously by many environmental factors, including natural environmental factors (high temperature, low temperature, humidity, freezing, thermal shock, rainfall, saltwater, solar heat, sand/dust, mold, etc.) and induced environmental factors (runway taxi vibration, turbulence-induced vibration, aerodynamic vibration, engine vibration/noise, acceleration, aerodynamic noise/pressure, sonic shock waves, gun vibration/shock, aerodynamic heating).

Accordingly, these environmental conditions must be analyzed and reflected in the design during the development planning stage to ensure functionality and performance. The functionality and performance must be verified under such environmental influences. Furthermore, the aircraft mounting the air-to-ground missile must verify functionality and performance in the mounted configuration to ensure flight safety and obtain airworthiness certification.

▲ Types of Environmental Testing = Considering many environmental factors, environmental testing for all weapon systems can be classified into Environmental Stress Test (EST) and Environmental Stress Screening Test (ESST).

Environmental Stress Testing simulates environments encountered during the life cycle to verify durability and reduce random failures, with MIL-STD-810 being a representative standard. ESST is conducted at manufacturing plants to detect manufacturing defects and reduce early failures. EST can be broadly categorized into Climatic Environmental Tests (temperature, solar heat, rainfall, etc.), Dynamic Environmental Tests (vibration, shock, acceleration, acoustics, etc.), and Combined Environmental Tests that simulate multiple environmental factors simultaneously (vibration/humidity-temperature combined, vibration/humidity-temperature/altitude/solar heat combined, vibration/temperature/acoustic combined, etc.).

Environmental factors may appear independently, but most environmental influences on Earth occur in combined environments. However, due to limitations in test equipment development technology, independent tests are mainly conducted, with some tests performed using combined methods.

Generally, electrical and electronic products undergo rapid model changes driven by market demands, requiring fast environmental testing. To identify latent defects during production and mass production, Highly Accelerated Stress Screening (HASS) tests are conducted as a type of reliability test.

Since product failures tend to occur in combined environments rather than single environments, Combined Environmental Reliability Tests (CERT) that combine multiple environmental conditions are increasingly performed as reliability tests. This approach significantly shortens the duration of environmental testing.

This content was produced with the assistance of AI translation services.