You need to overcome the gravitational force pulling an object down if you want it to lift upwards. Helicopters make this happen with the application of Bernoulli’s principle. The rotation of the rotor blades ultimately creates a low pressure air at the top of the helicopter. This is relative to its bottom portion, which generates an upward thrust or push.
If you see that your RC helicopter is not lifting off, it has something to do with the physics. However, your first reaction will be of astonishment, especially when it was functioning well the day before. Of course, you’ll be wondering what the cause behind this really is. Well, there are some common reasons behind an RC helicopter’s inability to lift off. Here, we’ve listed some of them:
1. Weakened battery
The weakening of the batteries in your RC helicopter is the most common reason for it not lifting off. In this case, the first thing you must do is check whether the batteries have full charge in them. This is quite obvious, but you must understand that charging them doesn’t mean they’re working at their fullest.
If they’re quite old and have run several cycles, they’ll lose their power and develop certain issues. You must use a multimeter to check the voltages. A battery cell that carries a full charge should have a voltage of 4.2 volts.
2. Loose or broken shaft
You must check if your RC helicopter’s shift linkage is weak. You must do this especially when your RC helicopter is not lifting off even with a good battery. Having a weak shaft linkage leads to the weakening of upward thrust. This prevents the helicopter from lifting off. Upon trying to rotate the hollow shaft, you should see the inner shaft moving along with it. If it is loose and wobbly, you’ll need to fix it.
This is exactly the same with the blade holder. The looseness becomes a cause for a loss of a considerable amount of rotational force transfer from motors to the blades. You must ensure that the screws holding the blade holder and the hollow outer shaft are in alignment. They must also be tight with the inner shaft.
3. Worn gear
A worn gear also prevents your RC helicopter from lifting off. In such a situation, you must try spinning the prop blades around slowly. While doing this, see if you feel any resistance. If you can feel any resistance, it will be a case of drawing out extra power from the motors. This will ultimately have an additional negative effect on wearing the batteries over a period of time. Most probably, the culprit here is the gear.
4. Worn blades
Don’t forget to take a closer look at the propeller blades of your RC helicopter as well. Check for signs of wear, whether they have cracks, or they’re breaking. The presence of even the slightest crack can hamper the propeller’s overall ability of a strong angle of attack. It prevents your RC helicopter from lifting off.
A propeller blade wears out over a period of time. This can also affect the angle of attack. It increases the amount of drag and turbulence, which limits an upward thrust or push. If you feel that the propeller blade of your RC helicopter needs replacement, you must go ahead with it.