Archive for January, 2009

Introduction to Mini RC Helicopters


Introduction to Mini RC Helis



If you’re reading this, then you’ve no doubt seen a micro RC helicopter at the mall or at Wal-Mart. The vendor sure does look like he’s having fun as he zips one around the mall. They’ve come down in price and it sure is tempting to pick one up and see what all the fuss is about! Can you really bring them home, flip a switch and be flying around your living room in just a few minutes?


Flying an RC Heli

A helicopter is a complex machine that takes a skilled pilot just to accomplish something as simple as a steady hover above the ground. There is a lot more to flying a heli than just an accelerator, brake and steering wheel, as on a car! The pilot uses pitch, yaw, throttle and a combination of controls to allow the heli to move almost at will through the air. A micro heli simplifies these controls, to make it easier to fly. This means that you might not be able to sweep through your living room, banking left and right as you wind your way through furniture, but it is still a huge amount of fun!

A full frame RC helicopter generally has 6 channels of control. A micro heli starts off with 2, throttle and rudder. This allows you to lift off the ground and spin left and right. Forward flight is only possible by weighting the nose of the aircraft, but this generally makes it unstable when you want to hover and keep it still in the air.


Toy VS Hobby?

The majority of mini and micro helis found at department stores are classified as toys. They are inexpensive, easy to fly, and the perfect fit for the kid (or kid at heart!) with only a casual interest. If you’re even considering taking the interest further and taking up the hobby of Radio Controlled helicopters, then it is best to shy away from the Wal Mart helis and read a little further before you buy!


With a few exceptions, the toy helis tend to use unconventional controls such as a pistol grip or joystick control. Pretty neat stuff, but it will make it more difficult to later grow accustomed to the standard two-stick radio that most hobby kits utilize. Start off with the standard format, and you’re a few steps ahead if and when you take the next step. As addictive as this hobby can be, you might want to go ahead and plan on it!


Even if the $25 toy heli does have a standard two-stick control, it is not likely that replacement parts or upgrades are available for that kit. What goes up, must come down, and when helis crash, they can break. Small, micro helis are super lightweight and are less likely to break in the small impact of a crash, but it does happen. Spending a little bit more on a hobby-grade heli often allows you to buy inexpensive repair parts, or even go wild with trick aluminum and carbon fiber upgrades! Ebay is full of inexpensive upgrade parts that can improve the flight of your heli and make it more robust.


NEXT: Choosing the right heli for you


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Beginner’s RC Heli Buyer’s Guide - Part 2

We’ve discussed various formats of helicopters and you’ve probably (wisely) decided on a coaxial heli on which to learn basic flight skills. But there are more decisions to be made before you place that order for the heli of your dreams! All too often, hobbyists make the mistake of jumping directly to the most extravagant large format model with 6 channels, carbon fiber and anodized aluminum everywhere and end up frustrated when they are unable to fly it and end up breaking expensive parts.


2-Channel Helis

There is a lot to think about when you are flying a heli. It can be very taxing so it is best minimize the number of things to consider and focus on basic flight at first. A basic 2 channel coaxial micro heli will get you flying in no time at all, as they are very small, stable and will allow you to quickly master the basics of tail-in hovering. The two channels of control give you lift (throttle) and yaw (rotation left and right).

One of the most popular manufacturers in this class is Syma. The Syma 9093 Dragonfly and Syma 9083 enjoy a strong aftermarket of replacement parts and upgrades. While these are conventional tail-rotor helis, their micro size and 2-channel operation makes them easy enough to fly right out of the box.

Popular coaxial models in this class include the beautiful AH-64 Apache that looks good enough to display on the bookshelf!


3-Channel Helis

This is the most popular entry-level hobby-class helicopter, as it allows forward flight. Moving the left stick forward or back gives throttle and causes the heli to lift up or drop down. Moving it side to side spins it around to allow you to turn around. Adding a third channel of control allows the heli to fly forward. This will allow the pilot to practice one of the most basic maneuvers in the learning process, tail in flight away from you, then a turn and flight back. This is harder than it sounds, as left become right and right becomes left on the return trip!

Syma also manufactures several popular 3CH kits such as the Syma S001 and the more recent all-aluminum Syma S006 model. While the S006 does offer some very nice upgrades, and does share some parts with the S001, the beginner may want to consider the availability of replacement parts as the S001 has been on the market for a while, which makes it pretty easy to find replacement parts.


4-Channel Helis

A 4CH helicopter is a little bit more challenging to fly, and may not be the most suitable for some beginners, but is capable of much more realistic flight. In addition to throttle/lift, yaw/rotation and forward/backward pitch, it adds left/right roll. This allows for not only more advanced turning and sideways motion, but generally improved forward flight as the swashplate has more movement, generally being controlled by two servos.


Flight control would look something like this:



We’ll go into the physics involved in cyclic blade motion in later articles, as the mechanics involved are very complex. These are remarkable machines in both their flying ability and engineering/construction. The fact that a beginner can pick up a Ready-To-Fly 4-Channel helicopter complete with electronics, battery, charger, and transmitter for well below a hundred dollars is causing the heli segment of the RC hobby to see massive growth in the past few years.


Some of the more popular coaxial 4CH models include the E-Sky Lama V4 RTF, the Walkera 5#6-1 and the E-Flite Blade CX2. These are considered “mini” helis and require a larger indoor space in which to fly. There are some micro 4-Channel models, but they are few and far between due to the added complexity. The Walkera 4#3 Dragonfly is one of the smallest in this class.


Again, it is important to take into consideration the availability of replacement parts, as the beginner is sure to go through many sets of main blades, skids, and even drivetrain gears in their quest to learn to pilot these machines. It is relatively easy to find replacement parts for the Esky Lama V4, and even upgrade parts to customize your heli, improve flight and increase durability.



NEXT: Learning to Fly


Beginner’s RC Heli Buyer’s Guide

Okay, so you’ve decided that you want to buy a cool RC heli. You’ve either decided to pass on a toy heli, or you already bought one and are ready for something more. You might be surprised to find that there are a good number of RTF (Ready-To-Fly) Helis available that only cost marginally more than a toy heli, and are much more capable, as well as repairable! First you’ll want to educate yourself on the various formats available to choose the one that’s best for you.


Coaxial VS Tail Rotor

Conventional Tail Rotor Heli

Conventional Tail Rotor Heli

Coaxial Helicopter

Coaxial Helicopter

A helicopter uses rotating blades to provide lift. The speed at which they travel (throttle) and the angle at which they cut through the air (pitch) dictate how much thrust is produced. The problem is that the torque produced by the rotors would spin the body of the aircraft around if there weren’t a sideways thrust to compensate. A conventional heli uses a tail rotor to control yaw (the left/right spinning action). While this does produce a slight amount of sideways movement, on board electronics automatically compensate for this motion using a gyrometer, or gyro, for short. A gyro senses tilt using the acceleration of gravity and the on board computer compensates for this tilt by changing the pitch of the blades as they travel around in a circle.

But we’re getting way ahead of ourselves! We’ll talk more about the physics involved in later articles. Right now, we just want to choose a heli that suits us best.


A coaxial heli uses counter-rotating blades that both produce lift, but counteract the torque each one produces, since their motion is equal and opposite the other set of blades. While it looks somewhat unusual, this arrangement makes for a very stable helicopter without any built-in sideways thrust since it lacks a tail rotor. To spin around, all that needs to happen is for one set of blades to spin faster relative to the other blades.


So why aren’t all helicopters coaxial? Well, for one, they are generally heavier, as there are two sets of main blades, complete with propulsion, gear drives and two main shafts (usually a hollow shaft that contains a solid shaft within). Using a tail rotor keeps the heli lightweight and nimble, capable of unimaginable acrobatics! This is not to say that coaxial helis aren’t nimble, but they do have limitations. One of them is blade strike.

Blade strike occurs when one or both sets of counter-rotating blades is at full pitch, twisting and angling until they hit each other. Most coaxial RC helis have sufficient blade spacing that this will not occur unless you are a very advanced pilot indeed. And extended main shafts are often available to increase the heli’s capabilities as your skills improve.


Ok, so it’s fairly obvious that a beginner would be best suited with the stable flight characteristics of a coaxial heli. Some choose to go directly to a heli with a tail rotor design and have great success, as advances in electronics have enabled for much more stable flight. Particularly indoors, were there is little breeze apart from that coming from the rotors. So what else should the beginner pilot take into consideration when choosing their first heli?


NEXT: Number of Control Channels.