How to Choose a Fixed-Wing Motor: A Complete Guide

I. First, Clarify 3 Core Premises (Must Be Determined First)

1. Aircraft Type and Purpose (Determine Power Style)

• Trainers/Gliders/Aerial Surveying: Priority to long flight time and efficiency → Low KV, large propeller, high voltage

• Racing/Acrobatic Aircraft: Explosive power and high speed → Medium-high KV, medium propeller, 4S–6S

• Load-Carrying/VTOL Fixed-Wing: Large thrust and torque → Large size, low KV, 6S–12S

2. Thrust-to-Weight Ratio (Is the Power Sufficient?)

• Training/Aerial Photography: 0.6–0.8 (stable takeoff and cruise)

• General/Acrobatic: 0.8–1.2 (short takeoff, mild rolls)

• Racing/3D: 1.2–2.0+ (violent acceleration, vertical climb)

3. Battery Cell Count (Voltage)

• 1S–2S: Mini indoor aircraft

• 3S (11.1V): Entry-level aircraft (500–1000g) (Surfer, Cessna)

• 4S (14.8V): Medium-sized aircraft (1–2kg) (mainstream)

• 6S (22.2V): Large/aerial photography/load-carrying aircraft (2–5kg) (higher efficiency)

• 8S–12S: Industrial/long-endurance aircraft (5kg+)
  
  
  
  
  
  
  

II. How to Read Key Motor Parameters

1. Size (Stator Specification)

• First two digits: Stator diameter (mm) (larger = can handle larger propellers and higher power)

• Last two digits: Stator height (mm) (longer = higher power/torque)

• 2212 / 2216: 3S–4S, 500–1200g, 6–8-inch propeller (mainstream entry-level)

• 2814 / 2820: 4S–6S, 1.2–2.5kg, 9–12-inch propeller

• 3508 / 3510: 6S, 2.5–4kg, 13–15-inch propeller

• 4114 / 5012: 6S–12S, 4kg+, 16-inch+ large propeller (load-carrying/long-endurance)

2. KV Value (Speed Characteristic, Most Critical)

• Low KV (<1000): High torque, suitable for large propellers, high efficiency, long flight time

• Application: Gliders, aerial photography, surveying, long endurance

• Medium KV (1000–2000): Balance between thrust and speed

• Application: Trainers, general fixed-wing, coach planes

• High KV (>2000): High speed, suitable for small propellers, high peak thrust, fast power consumption

• Application: Racing, acrobatics, high-speed aircraft

• 3S: 1500–2400KV → 6–8-inch propeller

• 4S: 1000–1800KV → 8–10-inch propeller

• 6S: 600–1000KV → 12–15-inch propeller

• 8S–12S: 300–600KV → 16-inch+ propeller
  
  
  
  
  
  
  
  

3. Outrunner vs. Inrunner (95% of Fixed-Wings Choose Outrunner)

• Outrunner

• Advantages: High torque, direct drive for large propellers, high efficiency, good heat dissipation, low vibration

• Disadvantages: Slightly lower maximum speed

• First choice for fixed-wing (aerial photography, long endurance, conventional models)

• Inrunner

• Advantages: Extremely high speed, small size, fast response

• Disadvantages: Low torque, requires gearbox, high heat generation, expensive

• Application: Racing aircraft, EDF ducts, high-speed small aircraft

4. Power and Current

• Continuous Power: The power the motor can output for a long time (fixed-wing focuses on this)

• Peak Power: Short-term explosive power (for reference only)

• Current:

• ESC current ≥ Motor maximum current × 1.2–1.5 (leave margin)

• Battery discharge C-rate ≥ Maximum current / Capacity (e.g., 35A battery requires 35C or higher)

III. Fixed-Wing Motor Selection Steps (Directly Applicable)

1. Check Aircraft Parameters

• Takeoff weight, wingspan, recommended propeller diameter, thrust-to-weight ratio requirements

2. Determine Battery Cell Count

• 3S for small aircraft, 4S for medium-sized, 6S+ for large/high-efficiency models

3. Select Motor Size

• Corresponding to weight: 500g→2212, 1.5kg→2814, 3kg→3508

4. Match KV and Propeller

• Large propeller → Low KV; Small propeller → High KV

• 40–60% cruise throttle for highest efficiency (do not run at full throttle for a long time)

5. Match ESC

• Motor maximum current ×1.2~1.5

• Example: 30A motor → 40–50A ESC

6. Verify Thrust-to-Weight Ratio

• Thrust ≥ Weight ×0.8 (general); ≥1.2 (racing)

IV. Recommended Configurations for Common Aircraft Types (Copy Directly)

1. Entry-Level Trainer (500–800g, Surfer X8, Cessna)

• Motor: 2212 / 2216, 1800–2400KV

• Battery: 3S 1500–2200mAh 25C

• Propeller: 7–8-inch 2-blade propeller

• ESC: 30–40A

2. Medium-Sized Aerial Photography/Surveying (1.2–2.5kg)

• Motor: 2814 / 2820, 900–1500KV

• Battery: 4S 3000–5000mAh 30C

• Propeller: 10–12-inch high-efficiency propeller

• ESC: 40–60A

3. Large Long-Endurance/Load-Carrying (3–6kg)

• Motor: 3508 / 4114, 500–800KV

• Battery: 6S 5000–10000mAh 35C+

• Propeller: 13–16-inch large propeller

• ESC: 60–80A

4. Racing/Acrobatic Fixed-Wing

• Motor: 2812 / 3010, 1800–2600KV

• Battery: 4S–6S

• Propeller: 6–8-inch high-speed propeller

• ESC: 60–100A

V. Selection Pitfalls (Most Common Mistakes for Fixed-Wings)

• ❌ High KV with large propeller → Excessive current, overheating, burning motor/ESC

• ❌ Only focus on KV, not size → Small motor carrying large propeller leads to direct overload

• ❌ No margin for ESC → Overcurrent protection easily triggered at full throttle

• ❌ Cruise throttle too high → Low efficiency, short flight time, motor overheating

• ✅ Fixed-Wing Secret: Large propeller + Low KV + High voltage = Most energy-saving and longest flight time

Summary (One Sentence)