How to Choose the Right Resistors for Aerospace Applications

Among the many passive components integrated into modern aircraft systems, resistors are particularly imperative for regulating electrical current, dividing voltages, filtering signals, and protecting sensitive circuitry. These parts help maintain stable electrical performance under some of the harshest operating conditions known to engineering, so selecting the right resistor for an aerospace system goes far beyond choosing the correct resistance value. To help readers be better equipped to select the most effective type, this blog will cover the advantages, drawbacks, and appropriate uses for a few resistor variants that are regularly used in aerospace applications.

Understanding the Requirements for Aerospace Resistors

Before examining specific resistor types, it is first essential to understand the stringent demands placed on electronic components used within aerospace systems. Resistors present in commercial airliners, military aircraft, and space-bound platforms must have attributes like:

• Electrical Stability and Tolerance Control: Aerospace applications demand minimal variance in resistance values, so resistors need to exhibit tight tolerances and low temperature coefficients to maintain stable system performance.
• Resistance to Vibration and Shock: Resistors in these settings are likely to be exposed to continuous vibration and sudden impact forces. Therefore, they have to be accommodated without degradation or drift in electrical performance.
• A Wide Operating Temperature Range: Aerospace resistors are expected to maintain stable resistance values across broad temperature bands, often from −55°C to +200°C or higher depending on their placement.
• Moisture Resistance and Hermetic Sealing: Exposure to humidity, condensation, or rapid changes in pressure can compromise resistor integrity. As such, hermetically sealed designs or moisture-resistant coatings are often necessary to protect internal elements.
• A Lightweight and Compact Form: In aviation, component size and mass are critical factors, so resistors need to balance performance with physical dimensions that are as minimal as possible.

Common Resistor Types Used in Aerospace

Fixed Resistors

Fixed resistors are suitable for nearly all aerospace electronic systems, maintaining a constant resistance value regardless of voltage or temperature fluctuations. With their predictable performance, they are particularly indispensable for tasks such as power regulation, signal conditioning, voltage division, and electromagnetic interference (EMI) suppression. In this category, two variants stand out:

• Metal Film Resistors: Constructed with a thin metal alloy layer on a ceramic rod, metal film resistors offer high precision, low noise, and excellent temperature stability. These qualities make them perfect for navigation equipment and flight data computers. However, without proper coating, they can be susceptible to damage in high-humidity environments.
• Wirewound Resistors: Made by winding resistive wire around a ceramic or fiberglass core, wirewound resistors are valued for their high power ratings and long-term stability. They are usually found in power distribution units, braking systems, and radar components, but their inductive nature makes them less ideal for high-frequency circuits.

Thin Film Resistors

Thin film resistors are made by depositing an extremely thin layer of conductive material—often nichrome—onto a ceramic substrate. Boasting very tight resistance tolerances and low temperature coefficients, these resistors are reliable for precision aerospace electronics, including instruments like altimeters and gyroscopic control systems. However, their higher manufacturing cost and sensitivity to mechanical stress can be limiting factors.

Thick Film Resistors

In contrast to thin film variants, thick film resistors are made by applying a relatively thicker layer of resistive paste onto a ceramic substrate. While they do not match the precision of their counterparts, thick film resistors are more durable and significantly more cost-effective for large-scale production. Suitable for tasks like in-flight entertainment and environmental control units, their higher temperature coefficients and reduced precision can be a drawback in applications requiring tight resistance tolerances.

Power Resistors

Engineered to dissipate substantial energy loads, power resistors are constructed from ceramic or metal composite materials that display high resistance to thermal stress. As a result, these components are widely used for brake energy dissipation in electric thrust systems, limiting inrush current during auxiliary power unit (APU) startup, and regulating voltage in generator systems. The two most popular construction methods are:

• Ceramic-Encased Resistors: Featuring a ceramic outer casing that acts as an effective insulator and structural shield, these resistors are durabile in the face of thermal cycling and mechanical shock. Due to this, they can be placed in high-temperature sections of an aircraft, such as those near propulsion or power generation systems.
• Aluminum-Housed Resistors: These power resistors feature an aluminum casing that offers both a protective enclosure and an integrated heatsink. Aluminum’s high thermal conductivity enables efficient heat dissipation, allowing the resistor to handle higher power loads in compact spaces like engine compartments or electronic bays.

Fusible Resistors

Fusible resistors serve a dual purpose by functioning both as standard resistors and as fuses. When exposed to excessive current, the internal resistive element is designed to melt, thereby opening the circuit and preventing damage to downstream components. This built-in protection benefits sensitive aerospace power supplies and safety-critical modules while helping to reduce overall component count and weight. However, once tripped, they need to be replaced.

Variable Resistors and Potentiometers

Although they are not often deployed in aerospace due to their mechanical complexity and susceptibility to wear, variable resistors and potentiometers can aid systems requiring manual or feedback-based adjustment. They are typically found in sensor calibration modules, cabin lighting adjustment circuits, and thrust vectoring feedback loops, where controlled resistance variability is crucial for fine-tuning system performance. To optimally meet these demands, variable resistors and potentiometers must be integrated with rugged enclosures and environmental sealing.

Aerospace Purchasing: A Trusted Source for Aerospace-Grade Resistors

As we established, there is a vast array of resistor types that meet aerospace system requirements, each with their own benefits and limitations that should be carefully considered before implementation. While selecting the appropriate resistor is a large part of the equation, reliable sourcing is equally vital to secure products that meet required quality benchmarks. Aerospace Purchasing, a platform operated by ASAP Semiconductor, has you covered with a large inventory of industry-compliant resistors and various other parts.

All items on this website are sourced from vetted manufacturers and suppliers, allowing you to confidently fulfill all aerospace component needs in one place. We also have the expertise and resources to deliver your desired components with efficiency, competitive pricing, and care given to all of your unique requirements. If you are ready to see how we can assist you, explore our offerings and get in contact with us today.