Frequently Asked Questions
From RC Helicopter Wiki
Please feel free to leave questions you would like answered on the Discussion page, linked above!
I want to learn to fly model helicopters. What is the best way to go about this?
- Welcome to the fold! Probably the best way to learn to fly is to find a group of like minded people locally and ask their advice. Most countries have a model aeronautics body that can help you find your local flying group.
- If you don't have access to such a group, then it is not impossible to teach yourself to fly, at a price. If you just want a small helicopter to buzz around the house or sports hall, there are a number of small electric coaxial helicopters that are relatively easy to fly with some practice. If you wish to take it further, your best bet would be a simulator, which will very quickly pay for itself. Beginners are often recommended to work through Radd's school of rotary flight.
- There are two schools of thought regarding a first helicopter. One school suggests getting a large helicopter, such as a 30-sized nitro powered helicopter, as these are more stable, and thus easier to fly. The other school suggests starting with one of a variety of small electric helicopters, on the grounds that they are much cheaper to crash. In the end, it is likely your circumstances will dictate which way you go; if you are flying in a public place, anything larger than a 450-sized electric helicopter is likely too dangerous.
- You could try our Beginners start here page, which isn't very good at the moment, but contains a few links to places that are.
Are model helicopters dangerous?
- Most mechanical items are dangerous if operated carelessly. The primary danger comes from the main rotor, and to a lesser degree the tail rotor. Small helicopters such as coaxials may sting a bit if flown into someone. Larger helicopters, such as the 450 sized T-Rex could easily cause a lot of blunt impact trauma and moderate to severe lacerations requiring medical attention, but I suspect not much permanent damage unless the victim were unlucky. Larger helicopters could easily dismember and kill.
What do the different size numbers mean?
- See Helicopter sizes.
- See Helicopter types.
I switched my transmitter off and the helicopter went mad and killed itself!
- Don't do that. Always switch on the transmitter, and then the helicopter, and afterwards switch off the helicopter first and then the transmitter. If this happens with a 2,4GHz system, then you need to rebind your receiver and transmitter to set up the failsafes correctly. Cheap radio systems on ready to fly helicopters can be prone to dangerous glitching at the best of times.
Swashplate Movement Directions
I can't get my swashplate to move in the correct direction on my Trex, Mini Titan, or other CCPM helicopter!
- We have an entire page on CCPM setup, but it may be more than you're looking for right now. Use servo reversing to get the servos moving the swashplate up and down together when the throttle/ collective is used. Then use you transmitter's CCPM parameters (also called Swashplate mixing, and a variety of other things) to get collective, aileron and elevator moving in the correct direction by the correct amount. Changing the sign from positive to negative (or vice versa) reverses the direction of that control.
Directions of Blades
What direction are the blades supposed to rotate?
- Viewed from above, the main rotor of nearly all model helicopters rotates clockwise (a coaxial of course has one set rotating in each direction). The tail rotor should rotate so that the blades come 'up' towards the front of the heli. Blades should be mounted so they are traveling thick edge first.
Drifting in one direction
Why does my helicopter drift to the left? Can I trim that out? Why does my helicopter lean in the hover?
- Assuming your swashplate is level, and your helicopter is correctly balanced, your helicopter drifts to the left due to translating tendency. You can't trim it out completely. You can get small wedges that fit between the helicopter body and the skids to put the helicopter close to the correct angle before it leaves the ground. Most pilots just input a small stab of right cyclic as they come off the ground.
- You might want to look at our cyclic trimming guide.
My helicopter won't stop spinning!
- There are four possibilities:
- * It is possible that the tail pushrod length or servo position needs to be adjusted to provide the correct amount of tail rotor thrust.
- * It is possible that the gyro sense is incorrect, and needs reversing, or the gyro needs otherwise configuring.
- * It is possible that mechanical set up of the tail rotor is incorrect somehow, such as spinning the wrong way, or not having the control links on the leading edge of the blade.
- * It is possible that you have insufficient tail rotor speed, due to insufficient head speed, a failing tail motor, or a damaged drive or battery..
You could try our page on tail setup to solve the problem.
My helicopter vibrates. What's wrong with it?
- If you've crashed it, there are likely a number of bent or damaged parts, which could include: the main mast, the feathering shaft, and the tail shaft. If you've replaced the main blades, they may well need balancing and tracking.
- Bent main shaft: take off blades and see if the head assembly spins uniformly
- Blades of unequal weight: use blade balancer
- Flybar not installed in the center
See Vibration for more detail.
Tail Bobbing up and down
- Low head speed
- Blades too tight in blade grips
- Tight head damping
- Adjust angle of paddles slightly
Servos glitch randomly
- Interference from outside sources: if you are using a 900 Mhz radio, look into using a 2.4Ghz radio as they have less interference
See Glitch for more information.
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