Radome Bird Strike Impact Test

Abnormal events such as bird strikes can occur at any time. When an aircraft is struck by birds or foreign object debris, the proper inspection process must be followed to determine whether the aircraft is airworthy before the next flight.

A radome is an aerodynamic, weather-resistant enclosure that protects the radar antenna. It is constructed from materials that allow the radar to transmit and receive radio waves with minimal interference. All radomes on commercial aircraft consist of a composite sandwich structure consisting of a honeycomb core sandwiched between inner and outer skins.

A bird strike or other foreign object can cause the sandwich composite structure to deform and then return to its original shape with little or no damage to the exterior, but potentially significant damage to the interior can occur. In-service experience shows that while the radome's exterior typically leaves minimal impact scarring, the honeycomb core may be damaged, and the radome's interior may shatter around the impact site.

If bird strike damage is not detected on the ground, the damaged area will undergo several flight cycles. The air trapped between the honeycomb and the separated surface tends to inflate with each flight, creating a bubble where the surface is disrupted by the low ambient air pressure at altitude. If the damage is not detected, depending on its size and location, it can disrupt the movement of the weather radar antenna and trigger weather radar warnings.

Bird strikes pose a significant threat to aviation safety, particularly during takeoff, landing, and low-altitude flight. Among the most vulnerable aircraft components in such incidents is the radome, the aerodynamic and weatherproof enclosure that houses the radar antenna, typically located in the aircraft's nose. Radomes are designed to withstand high-speed airflow and environmental impacts, but they are not particularly resistant to high-energy impacts from bird strikes.

A radome (radar dome) is a structural, non-metallic enclosure designed to protect radar and other sensitive electronic equipment. Typically constructed from advanced composites such as fiberglass or carbon fiber-reinforced polymers, radomes must balance three critical properties:

• Electromagnetic transparency: Allows radar signals to pass through without distortion.
• Aerodynamic design: Provides smooth airflow and reduced drag.
• Structural integrity: Resistant to environmental and operational stresses.

Because of their location in the aircraft's nose, radomes are often the first point of contact in a bird strike. The effects of a bird strike on radomes include:

• Structural damage: When a bird collides with a radome at high speed, the energy transfer can cause:
  • Cracking or perforation of the radome shell
  • Delamination or fiber breakage in composite materials
  • Complete penetration exposing the radar system
• Radar system failure: Damage to the radome can compromise radar operations by:
  • Signal attenuation or reflection due to deformed surfaces
  • Do not allow water or debris contamination into the radar compartment.
  • Causing short circuits or power outages in electronic components
• Aerodynamic degradation: A damaged radome alters airflow characteristics, resulting in increased drag, reduced fuel efficiency, and in severe cases, potential control instability.
• Safety and operational risks: Bird strikes that endanger the Radome can force:
  • Diversions or emergency landings
  • Aircraft grounded for inspection and repair
  • Loss of situational awareness in case of failure of air or terrain radar in adverse conditions

High-speed military jets are particularly vulnerable due to the higher kinetic energy upon impact. Some radome failures lead to mission aborts and expensive maintenance cycles.

Radomes are tested for bird strike resistance as part of certification by the FAA and other regulatory agencies. Simulated bird strike tests (using gelatin projectiles of specific mass and velocity) are performed to evaluate:

• Impact resistance
• Material performance
• Post-collision radar functionality

The aviation industry uses several strategies to reduce radome bird strike risks:

• Material innovation: Impact-resistant composites are being developed and energy-absorbing layers are being used within the radome shell.
• Design optimization: Improved geometry is used to deflect birds rather than absorb direct impact. Improved bonding techniques are also being implemented to prevent delamination.
• Bird strike prevention systems: Radar-based bird detection systems are installed at airports and habitat management is implemented to reduce bird populations near runways.
• Inspection and maintenance: Regular visual and non-destructive inspection of radomes is carried out, and flight data is analysed to flag potential impact events.

Radome bird strike testing involves simulating high-velocity bird strikes on radome structures to evaluate their durability, failure modes, and continued radar functionality. These tests are essential for regulatory certification and safety assurance in both civil and military aviation. The primary test methods used are:

• Simulated bird strike test (bird strike test): This is the most direct and streamlined method for testing a radome's resistance to bird strikes. A simulated bird (usually a gelatin projectile) is launched into the radome using a gas gun or compressed air cannon. Typical bird masses range from 0,45 to 1,8 kg, depending on the aircraft type and phase of flight (takeoff, climb, cruise). Impact speeds suitable for operational conditions are typically 200 to 400 knots.

The standards based on these tests are as follows:

• FAA 14 CFR Part 25.775 (for transport aircraft)
• MIL-STD-3038 (for military aircraft)
• RTCA DO-160 Section 23 (environmental conditions and test procedures)

The evaluation criteria for these tests are as follows:

• Structural integrity of the radome after impact
• No punctures or excessive damage
• Continued functionality of radar systems
• The radome is not separated from the body

• Material characterization and failure analysis: This testing evaluates how radome composite materials behave under high strain rates and dynamic loads. These tests utilize the following techniques:
  • Dynamic mechanical analysis
  • Scanning electron microscopy of fracture surfaces
  • High-speed camera analysis to detect delamination, fiber pullout or penetration during impact
  • Determination of failure modes: delamination, cracking, fiber breakage

During the evaluation process, failure modes such as delamination, cracking and fiber breakage are identified and materials are compared.

• Post-impact non-destructive testing: The purpose of this testing is to detect internal damage or delamination that is not visible on the surface. Techniques such as ultrasonic testing, thermography, shear radiography, and X-ray radiography are used.
• Finite element modeling and simulation: The purpose of this testing is to model and predict bird strike behavior in radome structures prior to physical testing. Primary applications include simulating bird strike dynamics, optimizing radome geometry and composite layout, and reducing the need for multiple physical prototypes.
• Environmental and aging tests: The purpose of this test is to evaluate radome behavior under combined weathering and impact conditions. Thermal cycling, UV exposure, and moisture ingress tests are performed. Impact testing is performed to assess the effects of aging on bird strike resistance.

Consequently, radome bird strikes are a critical intersection between wildlife hazards and aircraft system vulnerabilities. While the frequency of such incidents is relatively low, their consequences can be severe, both financially and operationally. Ongoing advancements in materials science, radar technology, and wildlife management are crucial for improving radome resilience and ensuring continued flight safety against natural airborne threats.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide radome bird strike testing services to businesses.