Wrong CG and ignoring balance
Skipping the balance check is the most common beginner mistake in aeromodelling. Every model has a specified center of gravity (CG) position that ensures stable flight. Flying without checking the CG is a gamble. A tail-heavy model is longitudinally unstable and pitches up. A nose-heavy model dives and lands nose first.
Do not trust your intuition when balancing. Always check the CG on two fingers or a balance stand. Even experienced modellers check the CG before every flying session, especially after changes to the model (different battery, added equipment, repair after a crash).
No pre-flight check
Before every flight, perform a pre-flight check. It should cover: propeller tightness, control linkage connections, free movement of all control surfaces, drive and receiver battery voltage, a range check, and correct control surface directions.
Skipping the pre-flight check leads to failures that could easily have been caught on the ground. A reversed aileron or elevator direction is a classic mistake that ends in a crash within seconds of launch.
For free flight models the check covers: the DT timer, DT time setting matching the round, tow line condition, balance, wing symmetry and rubber tension (in F1B).
Launching downwind
Flying models are launched into the wind (facing the wind), not downwind. Launching into the wind gives a higher airspeed at a lower ground speed, which provides better control and faster lift generation.
A downwind launch means the model must reach flying speed plus the wind speed before generating lift. This results in a longer takeoff roll, a dangerously low pass over obstacles and a risk of stalling at low altitude. In free flight models, towing downwind causes a low launch and a risk of ground impact.
No rubber motor lubrication in F1B
In F1B models (rubber-powered), the rubber motor is the key propulsion element. The rubber should be lubricated before every winding session with a silicone-based or glycerin-based lubricant. Dry rubber loses elasticity, overheats during unwinding and snaps much sooner.
Lubrication extends rubber life, reduces internal friction and allows more winds, which translates to a longer motor run. Lack of lubrication is one of the most common reasons for rubber breakage at competitions.
No LiPo voltage check
In RC models, flying on a depleted LiPo pack leads to power loss at a critical moment (takeoff, climb) or to deep discharge that permanently damages the pack. Before every flight, check the pack voltage with a cell checker on the balance connector.
The minimum safe voltage to begin a flight is approximately 3.7 V per cell (a 3S pack should read at least 11.1 V). If any cell reads below 3.5 V, charge the pack before flying. Do not rely on the voltage indicator on the transmitter, which only monitors its own battery.
Ignoring weather conditions
Wind, turbulence and thermals have a huge impact on model flight. Beginners should fly in calm conditions: wind up to 3 m/s (about 10 km/h), no gusts, no storms. Strong wind reduces controllability, increases the risk of disorientation and makes landing difficult.
In free flight models, weather conditions determine the height gained from the tow and the model's behavior in thermals. Flying in rain is unacceptable (wet balsa loses strength, wet film changes the weight). Strong crosswind causes the model to drift and makes it hard to find after landing.
Before heading to the field, check the forecast. Pay attention to wind speed, gusts and direction. On the field, watch three indicators: grass, flags and smoke, which show local wind changes.
Not learning to manage throttle
In RC models with electric or combustion power, beginners tend to fly at full throttle for the entire flight. This causes excessive speed, difficulty in control and rapid battery depletion.
Learn to use the throttle according to the phase of flight: full throttle for takeoff and climb, 50% to 70% throttle for cruise, idle on the landing approach. The throttle is a third control alongside ailerons and elevator. On a simulator, practice approaches with the engine off (dead-stick landing) to learn energy management.
Too complex a first model
Choosing an aerobatic model, a multi-motor drone or a complex scale model as your first aircraft is a recipe for frustration. Such models require advanced piloting skills that a beginner simply does not have yet.
Start with a simple trainer with a large wingspan (1.2 to 1.6 m), a high wing and gentle wing dihedral. A foam trainer with electric power is inexpensive and easy to repair. After several dozen flights and a solid grasp of takeoff, straight flight and landing, move to a sport model. A gradual increase in difficulty is far more effective than trying to learn on a challenging model.