The motors used in radio-controlled (RC) model aircraft are essential for determining performance and flight experience. The two main technologies are brushed and brushless motors. Brushless motors, which are the most popular, offer superior energy efficiency with a performance rate of 85-90%, resulting in better battery life and less heat generation. They are powered by LiPo (Lithium-Polymer) batteries, typically with voltages ranging from 7.4V to 22.2V, and can deliver between 300W and over 5000W, depending on the model size. Brushed motors, while less efficient, are easier to maintain and are often used in entry-level models. Their power output generally ranges from 100W to 500W. Thanks to their low power consumption, brushless motors extend flight times, typically between 10 and 30 minutes, depending on battery capacity and aircraft size. Brands such as E-Flite, Turnigy, and Hacker are renowned for the reliability and performance of their motors in the RC aircraft industry.
1. Electric motors
Electric motors dominate the modern RC aircraft market due to their ease of use and low maintenance. These motors are powered by rechargeable batteries, with common options including LiPo (Lithium-Polymer) or LiFePO4 (Lithium Iron Phosphate) batteries, offering voltages ranging from 7.4V to 22.2V, depending on the model’s size and power requirements. In terms of output, motor power ranges from a few hundred watts for small aircraft to over 5000 watts for larger or competition-grade models. These motors are typically classified into three types: DC motors, brushless DC motors (BLDC), and brushed motors. Brushless motors are especially popular in RC aircraft due to their high energy efficiency and long lifespan, with efficiency rates reaching 85-90%.
Leading brands such as E-Flite, Turnigy, and Hacker provide high-performance motors suited for various aircraft types. E-Flite’s brushless motors, such as the Power 25, are highly recommended for medium-sized aircraft, offering 500W of power and enhanced reliability. These motors excel in achieving high rotational speeds while maintaining low energy consumption, thus extending flight time. While brushed motors are less efficient, they remain a viable option for budget-friendly models or beginners seeking minimal maintenance.
Characteristics of electric motors
- Power supply: Lithium-Polymer (LiPo) or Lithium-Ion (Li-ion) batteries.
- Maintenance: Low maintenance.
- Performance: Good energy efficiency, instant start, and precise control.
- Advantages: Less noise, no exhaust gases, ease of use.
- Disadvantages: Flight time limited by battery capacity, recharging required after each flight.
Examples of applications
Electric motors are used in a wide variety of models, ranging from hobby aircraft to competition models, as well as gliders and drones.
2. Internal combustion engines
Internal combustion engines (gasoline or methanol) are a popular option among experienced modelers due to their high power and longevity. These engines, often used for larger models, provide superior performance compared to electric motors. They are powered by fuels such as 2-stroke gasoline or methanol-oil mixtures for glow engines. Gasoline engines are generally more efficient, with power outputs ranging from 1.5 to over 30 horsepower (1,100W to 22,000W), while glow engines, more common in medium-sized models, range from 0.5 to 5 horsepower (370W to 3,700W). These engines are also appreciated for their long flight times, offering durations from 45 minutes to 1.5 hours, depending on the tank size and fuel consumption.
There are several types of internal combustion engines, including 2-stroke and 4-stroke engines. 2-stroke engines, such as those made by brands like DLE and Zenoah, are lighter and provide better power for smaller engines. 4-stroke engines, like those produced by OS Engines or Saito, are more complex but offer better efficiency and cleaner combustion. Although internal combustion engines require more maintenance, such as carburetor upkeep and spark plug management, they remain popular for full-scale model aircraft or vehicles requiring high power.
Characteristics of internal combustion engines
- Power supply: Gasoline, methanol, or hybrid fuel.
- Maintenance: Requires more maintenance (carburetor cleaning, fuel management, etc.).
- Performance: Higher power, long flight time, rapid climb.
- Advantages: Long flight duration, high power, less recharge time.
- Disadvantages: High noise, pollutant emissions, more maintenance required, higher initial cost.
Examples of applications
Internal combustion engines are used in large-scale models, such as aerobatic aircraft or more powerful propeller-driven planes, which require more torque for superior performance.
3. Turbine engines (Jet Engines)
Turbine engines, also known as jet engines, are the most advanced and expensive in the field of RC aircraft. Primarily used to simulate jet aircraft, these engines are ideal for passionate modelers seeking exceptional performance and impressive flight realism. Operating on the same principle as commercial jet engines, turbines use aviation fuel (Jet-A or Kerosene) or fuel specifically designed for model aircraft, such as JET-A1 fuel, allowing them to generate thrust ranging from 2 to over 100 kg, depending on the engine size. For example, small turbine engines can provide about 5 to 10 kg of thrust (10 to 20 N), while larger engines can exceed 100 kg (200 N).
These turbine engines typically operate at high rotational speeds, ranging from 50,000 to 120,000 RPM, providing exceptional acceleration and flight speeds, suitable for simulation aircraft such as military or civilian jets. Brands like JetCat, KingTech, and Wren Turbines are known for their expertise and high-quality products in this field. For example, JetCat offers models ranging from 5 to 70 kg of thrust, suitable for aircraft with wingspans ranging from 1.5 to 6 meters. However, these engines require specialized maintenance, proper storage, and come with a high price tag, often costing thousands of dollars, making them accessible mainly to experienced and professional modelers.
Characteristics of turbine engines
- Power supply: Kerosene or turbine-specific fuel.
- Maintenance: Complex and costly maintenance.
- Performance: Very high speed, exceptional maneuverability, stable flight.
- Advantages: High-speed flight, realistic jet flight simulation.
- Disadvantages: Very high cost, significant fuel consumption, loud noise, complicated maintenance.
- Examples of applications
Turbine engines are used in model jet aircraft such as the F-16, airliners, or fighter jets. These models are intended for advanced users and enthusiasts who seek extreme performance.
Comparison of engine technologies
| Criteria | Electric Motors | Internal Combustion | Turbine Engines |
|---|---|---|---|
| Power Source | LiPo or Li-ion batteries | Gasoline, Methanol | Kerosene, Jet fuel |
| Maintenance | Low | Moderate to High | Very High |
| Flight Duration | 20-60 minutes | Up to 3-4 hours | Up to 2 hours |
| Initial Cost | Low | Moderate to High | Very High |
| Power | Moderate to High | High | Very High |
| Noise | Quiet | Loud | Very Loud |
Conclusion
The choice of engine for an RC aircraft depends on user priorities, such as aircraft type, desired performance, and budget. Electric motors are ideal for beginners and lightweight models, while internal combustion and turbine engines are better suited for experienced users seeking high-performance flight.