Choosing a Flywheel: Application Fit and Specification Checks

What Is a Flywheel and Why Does It Matter for Spacecraft?

A Flywheel is a mechanical device used in spacecraft and satellite attitude control systems to store and release angular momentum. It operates by spinning at high speeds; when a change in orientation is required, the motor driving the wheel is accelerated or decelerated to produce the torque needed to adjust the spacecraft attitude.

Because flywheels store momentum mechanically, they deliver precise orientation control without consuming propellant. The system is maintenance-free, contains no moving fluids, and offers high long-term reliability -- qualities that make it well suited for geostationary satellites, scientific missions, and deep space exploration where attitude control must be sustained over extended periods.

Astralink Science and Technology Co., Ltd. supplies a range of flywheel models with differing angular momentum capacity, envelope, and interface characteristics. Understanding these differences is the first step to matching a model to your mission requirements.

Key Selection Criteria

1. Angular Momentum Capacity

Angular momentum determines how much rotational energy the flywheel can store and therefore how large an attitude disturbance it can absorb. The confirmed product range from Astralink Science and Technology Co., Ltd. spans from 50 mNms (at 9,000 rpm) up to 15 Nms (at 3,100 rpm).

Smaller satellites with limited disturbance environments can work with the 0.1 Nms or 50 mNms models. Larger platforms or missions requiring greater torque authority should evaluate the 0.5 Nms or 15 Nms models.

2. Output Torque

Output torque governs the rate at which the spacecraft can slew or recover from a disturbance. Confirmed output torque values are:

Applications requiring rapid attitude manoeuvres benefit from higher continuous torque. Where slow, fine-pointing stability is the primary goal, lower torque combined with higher angular momentum may be the better trade.

3. Envelope Size and Weight

Mass and volume budgets are among the tightest constraints on any spacecraft mission. Confirmed envelope and weight data for each model:

The 50 mNms model is the lightest option, with a wheel body under 160 g, making it well suited to CubeSat or nanosatellite buses where mass is tightly constrained. The 15 Nms model at approximately 9 kg is intended for larger satellite platforms.

4. Power Budget

Power is a constrained resource on spacecraft. The confirmed power values below apply in the context of operating three flywheels, as a standard attitude control configuration typically mounts wheels on orthogonal axes.

For power-limited small satellites, the SC-AOC-F-102-01 offers the lowest steady-state draw. The SC-AOC-F-102-04 requires adequate power generation capacity to support its peak demand of up to 75 W.

5. Working Voltage and Communication Interface

Interface compatibility with the satellite power bus and on-board data handling system is a practical procurement check that can rule out a model regardless of its performance figures.

If the on-board computer communicates via CAN bus, only the SC-AOC-F-102-02 is directly compatible. All other models use RS422. Voltage bus design further narrows the selection: the 15 Nms model requires a 30 V bus, while the three smaller models operate on 12 V nominal or a 9 to 12.5 V range.

6. Speed Control Precision and Working Modes

Speed control precision affects attitude determination accuracy. The SC-AOC-F-102-03 provides the most detailed precision specification: 0.2 rpm or better above 500 rpm, rising to 5 rpm or less below 100 rpm. Models SC-AOC-F-102-01 and SC-AOC-F-102-02 specify 1 rpm or better. No precision figure is listed for SC-AOC-F-102-04.

Working modes also vary across models. The two smaller models support Standby Mode and Speed Mode. The two larger models add Current Mode, which provides torque-level control authority.

Summary Comparison

Application Fit Guidance

CubeSats and nanosatellites with tight mass and volume constraints should evaluate the SC-AOC-F-102-02 (50 mNms) first. Its wheel body weighs under 160 g, operates on a 9 to 12.5 V bus, and communicates over CAN. If higher angular momentum is needed in a similarly small form factor, the SC-AOC-F-102-01 (0.1 Nms) stores twice the momentum at a total assembled mass of 0.83 kg and uses RS422.

Mid-range satellites requiring higher slew authority and fine speed control should consider the SC-AOC-F-102-03 (0.5 Nms). Its 15 mNm output torque and speed precision of 0.2 rpm or better above 500 rpm support agile or fine-pointing missions, and it operates on a standard RS422 interface at 12 V nominal.

Large satellite platforms, including geostationary or dedicated scientific spacecraft with substantial momentum storage needs, should evaluate the SC-AOC-F-102-04 (15 Nms). Procurement teams must account for its approximately 9 kg mass, 30 V bus requirement, and up to 75 W peak power draw when sizing the platform power and structural subsystems.

The confirmed supply cycle is 3 months for all four models. Pricing, export compliance, and mission-specific certification requirements are not addressed in available product materials; buyers should confirm these details directly with Astralink Science and Technology Co., Ltd.

About Astralink's Flywheel Product Line

Astralink Science and Technology Co., Ltd. develops and manufactures flywheel assemblies as part of its broader portfolio of satellite components and parts services. The four confirmed flywheel models -- ranging from 50 mNms to 15 Nms in angular momentum -- cover nanosatellite through large-platform applications. All models are self-contained units driven by an electric motor with a high-inertia wheel mounted on a bearing. They contain no moving fluids and consume no propellant, supporting maintenance-free long-duration missions.