Guide to Remote Control Model Helicopters, what is 2, 3, 3.5, 4, and 6 channel? Gyro? What to look for and what to buy

With the advent of lightweight lithium polymer batteries and powerful yet tiny motors, the genre of mini remote control model helicopters is available for a cheap price (as low as $25). They can be found in mall kiosks, Radio Shack, Best Buy, and similar electronics store, as well as toy stores and many other outlets. However, the cheapest stuff may not be ideal for you. This guide will explain all the buzzwords, and explain what to look for when it comes to buying such RC helicopters.

There are three ways to classify RC helicopters: engine, size, and sophistication.

Classify by Engine

There are four types of power used in RC helis: battery, nitro, gas, and turbine.

Battery Power: Vast majority of RC helis are powered by rechargeable battery. Recent advances in lithium polymer batteries allow an impressive amount of power to be stored in a lightweight package, and RC heli makers made use of them to deliver many minutes of flight time in such a tiny package. More sophisticated battery powered helis (mini or midsize) can use replaceable battery packs (keep a couple charged ones around!)

Nitro Engine: For longer flight duration, a nitro engine is needed. Sometimes known as a "glow engine", this type of engine is closer to diesel in that it does not use spark plug, but use a mixture of methanol, nitro-methane, and oil, thus the name. Fuel is expensive though. These engines runs at extremely high RPM, up to 17000 and makes a very piercing screech when powered up. Some people call these "gas engines", which is not correct.

Gas Engine: Some larger RC helis use a tiny 2-cycle gasoline engine. These don't generate as much noise as the nitro engines, and gasoline is available almost anywhere, and you just need some 2-cycle engine oil to go with it. On the other hand, they are pretty big for RC helis, and generally only appear on full and large sized helis (see below on size classifications).

Turbine Engine: for the ultimate in realism, you can't beat a miniature turbine engine, but these are extremely expensive, though the power they can generate with such a small engine is truly amazing (that's why they are used in real helicopters!) Parts are hard to come by.

Classify by Size

As you can see from the starting picture, size of the RC helicopter (its "scale") vary greatly, from little 8-inch micro heli (eSky Blade mCX 300) to huge 60 inches (5 ft!) Bergen Intrepid. They are generally grouped into 5 classes

Micro -- your typical "toy" RC heli found in Brookstone, Radio Shack, and such, about 6-12 inch total, fits in palm of your hand, battery powered. Majority of the RC helis will be in this size category. Cost ranges from $15 - 125 depending on sophistication, limited to up to 4 channel controls only, flight time of about 3-8 minutes on a full charge.

Mini -- 12-24 inches in length, this is appearing at a discount in some hobby and toy stores. Most are battery powered, though more sophisticated version may use the smallest nitro engine available. Cost is between $30-300.

Midsize -- 24-48 inches in length, this is what the sophisticated RC heli flyers use to achieve those incredible aerobatic maneuvers such as upside down, barrel roll, and so on. Usually 6 channel control, and very often nitro fueled instead of battery fueled.

Full Size -- 48 to 60 inches in length, these are not adversely affected by wind and can easily fly outdoors. In fact, they are so large you should NOT even try to fly them indoors (the exhaust fumes from the engines can be a problem). Their mass make them quite stable.

Large Size -- longer than 60 inches in length, size of a small child, these can easily reach ACTUAL speed of over 100 MPH (not scale speed!) and can easily be considered "drones". This can be powered by gas, nitro, or even miniature turbines.

Classify by Sophistication

In general, the more sophisticated the heli, the more control channels it has, but usually this is accompanied by increase in size. However, recent miniaturization allow the creation of 4 channel helis in 8-inch sizes.

There are three classes of RC helicopters by sophistication: toys, amateur flight, and pro flight.

Toys are the stuff you usually find in electronics and gadget stores, like Best Buy or Brookstone. They generally run between $25-75. They generally have 2-, 3-, or 3.5-channel control and the latest generation have "gyro stabilization". The heli itself generally fits on your palm. Typically these RC choppers have flight time of 3-5 minutes.

Amateur flight RC helis are quite a bit bigger 12-18 inches in length or larger, and have full 4 channel controls, and supports longer flight time and higher speeds. These helis costs from $50-150.

Pro flight RC helis are true helicopter miniatures with ability to change blade pitch, thus using 6 control channels, and often use nitro, gas, even miniature turbine engines, and is capable of inverted flight and full acrobatics. These are like $150 and up to $1000.

Please note that size itself while a general indicator, is not a TRUE indicator whether it is a toy or not. The E-FLite Blade series is a micro co-axial RC heli that looks very similar in size to the $15-30 toy RC heli sold in a toy store, but the Blade is a full-fledged 4-channel RC heli that costs about $100 that uses 2.4 GHz spread-spectrum technology with plenty of available replacement parts should you break a few things. On the other hand, you can get a 3.5-channel toy heli in 26 inch size that's simply dwarfs even some 6-channel birds.

Toy RC Helis comes in three types: 2-channel, 3-channel, and the latest variant, 3.5 channel which is 3-channel with speed control, gyro stabilization, and possibly other features.

These RC Helis are almost always ready-to-fly (RTF) out of the box. Just put in some batteries, charge up the heli itself, and you can start flying. No assembly is required.

The 2-channel RC Helis

The 2-channel RC helis usually fits on your hand, no more than 6-8 inches long. They are only capable of:

• Up / Down
• Turn left / turn right

Controls are Infra-red based, so you cannot fly them outdoors (the light will intefere with the controls). You also have to point the controller at the heli, and don't fly it around a corner or behind an obstruction. The range is limited to about 20-25 ft.

Usually, you have the primary remote control where you need to put in a lot of AA batteries (6 to 8). There's a cable you release from the remote to charge the heli which has a tiny port on the side with the on-off switch. Due to the size of the helicopter which limits the size of the battery, flight time is limited to about 3-5 minutes. Recharge time is 5-10 minutes. There are probably flashing lights to indicate a full charge.

This sort of RC heli only have 2 controls: throttle (Z-axis up-down) and turn (i.e. left right). This version usually have 2 rotors: the main rotor on top, and a tail rotor that points to the side. (See example below). Some variants have two counter-rotating main rotors instead of just a single rotor, but both rotors are driven by the same motor.

This version can only fly up/down and turn left/right. The vertical Z-axis movement is controlled by varying the main rotor speed. The heli turns left/right by varying the tail rotor speed.

The helicopter body is slightly nose heavy, thus giving the heli a constant slow forward speed. You can adjust the speed slightly by adding a small bit of weight to the nose of the helicopter, but don't overdo it.

This sort of helicopter is designed as disposable toys. Generally the rotors are just plastic and body is just foam. If you crash it, expect it to break, esp. if you have it fall from great heights.

As these are disposable, there would be almost zero replacement parts (though some Radio Shack models may have replacement main rotors available)

NOTE: Usually only one can fly in a room at a time, as the IR signals are not coded to specific "channels" and signals can get mixed up.

Pros: easy to handle, cheap to start ($15-30)

Cons: limited flight capabilities, cheaply built and easily broken, indoor only

Look for: cheap price, as these are disposable, try the 3-channel and 3.5-channel birds instead

The 3-channel RC Helis

The 3-channel RC helis usually fits on your hand, no more than 6-8 inches long, almost same size as the 2-channel birds. Though some slightly larger ones can go 12 inches or even longer. They are capable of:

• Up / Down
• Turn left / turn right
• Forward / backward

Controls are Infra-red based, so you cannot fly them outdoors (the light will intefere with the controls). You also have to point the controller at the heli, and don't fly it around a corner or behind an obstruction. The range is limited to about 30 ft.

Usually, you have the primary remote control where you need to put in a lot of AA batteries (6 to 8). There's a cable you release from the remote to charge the heli which has a tiny port on the side with the on-off switch. The small ones have 3-5 minute flight time with a full charge. The larger ones may go up to 10 minutes.

The 3-channel RC helis offers variable forward speed by changing the rotor arrangement. They have two counter-rotating main rotors, one going clockwise and the other counter-clockwise, and controlled by two separate motors. There is a third rotor in the tail (controlled by a 3rd motor), but this one points upward rather than side-ways like the 2-channel birds.

The 3-channel RC helis have a bit more freedom of movement in that it now has variable forward speed, rather than the fixed speed of the 2-channel birds. The vertical rise and fall is still controlled by the main rotors. By adding/subtracting RPM to both main rotors together, the heli rises and falls. By adding RPM to only one rotor, the rotational inertia causes the heli body to spin in the opposite direction, thus allowing the heli to turn left or right. Finally, by spinning the tail rotor, the tail can be pulled up inducing forward motion (or pushed down, thus fly backwards). Each channel controlls one motor.

These helis look cool, are relatively nimble, but they cannot fly sideways and do tricks real helicopters can. At the edge of performance the helis are not stable. It is quite possible to make the tail rotor pull so hard it flipped the heli over and cause a crash.

Construction-wise, the cheaper birds are still made of plastic and foam body shell, though higher-quality ones are available with metal skeletons and variety of replacement parts. Look for the ones with replacement parts available, or already in the box. Rotors and such do get beat up.

The 3-channel birds are the current "standard" though they are rapidly replaced by the newer "3.5 channel" birds. You can find 3 channel birds for about $25 online, $40 retail.

NOTE: Some 3-channel birds may allow setting to different "channels" so two birds can play in the same room. if you don't see this listed as a feature, assume they are "solitary", i.e. only one in each room.

Pros: still low cost, okay to handle

Cons: limited flight capabilities, not very stable at limit of performance, delicate and breakable

Look for: metal skeleton, replacement parts either already in the box or available for purchase

The 3.5-channel helis

The 3.5-channel RC helis are basically the same physically as the 3 channel birds. They usually fit on your hand, no more than 6-8 inches long though some slightly larger ones can go 12-18 inches, maybe even a little bigger (like that 26 inch long Double Horse shown on the right).

Controls are usually Infra-red based, so you cannot fly them outdoors (the light will intefere with the controls). You also have to point the controller at the heli, and don't fly it around a corner or behind an obstruction. The range is limited to about 30 ft. Some of the bigger ones may use 2.4 GHz radio control and their large size would allow them to be fly outdoors, albeit still with range of about 50-75 ft. Some recent variants skip RC and went to WiFi control, where it registers itself as a device on your WiFi network, giving you even more range depending on your local WiFi environment.

Usually, you have the primary remote control where you need to put in a lot of AA batteries (6 to 8). There's a cable you release from the remote to charge the heli which has a tiny port on the side with the on-off switch. The small ones have 3-5 minute flight time with a full charge. The larger ones may go up to 20 minutes. The latest ones may feature a microUSB port for charging. The big ones may even have swap-out battery packs.

Some recent models don't use regular remote control, but instead, features an IR transmitter that you plug into your smartphone and use an app on the smartphone to send control signals to the RC heli. However, this method is imprecise and not recommended.

Gyro / Stabilization / .5 channel

Answering concerns about lack of stability of the 3 channel birds, toy makers added tilt sensors (the same ones in your smartphones) better known as "gyros", to the bird's control logic to act as a dampener for the input. For example, the gyro senses that the chopper is already going at 30 degrees nose down and any more would cause the heli to nose over and crash. So it will stop further tail rotor command to pull the tail up.

However, limiting the controls is frustrating to more experienced users, so manufacturers added two sets of parameters. In the "amateur", or low-speed mode, the the controls are capped by the gyro at a lower level, thus limiting the amount of maneuverability you have, but also lessens the speed and potential damage. There is an option to switch to professional, or high-speed mode, where the controls are capped at a higher level, giving the player higher maneuverability as the risk of doing more damage to the heli upon collisions.

This available selection of high vs low speed became known as the 0.5 channel, as a "feature" to make them better than the 3-channel birds.

NOTE: Some of the better 3.5 channel birds can be set to different control channels to allow more than one bird in the same room at the same time.

Some of the 3.5 channel birds may have special features like actually shooting little plastiic missiles, or allow two helis on different control channels to "dogfight" and "shoot" each other down, with onboard sensors registering hits, and the victim drop 3 ft in height and spin "out of control" to simulate being hit.

Pros: more maneuverability, more stability, often replacement parts are available for repairs

Cons: still not true helicopter flight, low flight time, more complex than ever

Look for: metal skeleton, replacement parts in the box or available for purchase, multiple channels so several people can play at once, radio instead of infra-red control

Amateur RC Helis generally have 4 channels of control, allowing them to perform

• Up / Down
• Turn left / turn right
• Forward / Back
• Sideslip left / sideslip right

There are two general ways to do this: the toy grade, and the hobby grade.

Toy grade method to achieve 4 channel

Recent advances in battery and manufacturing have allowed toy makers to make 4 channel flyers cheaply by adding two side rotors (one on each side) to a 3-channel bird. However, this is just a kludge, as it is nowhere close to a real helicopter flight. One example is shown to right: the "Avatar" flyer RC heli.

To fly sideways, you simply have the side motors do a differential thrust: one goes up, the other goes down, which pushes the whole thing one one, and vice versa.

The rest of the chopper is identical to the 3-channel birds. These are toy-grade helis with IR controls, and often with no replaceable parts. Once they break, that's it.

Hobby-Grade method to achieve 4 channel

Other manufacturers, seeking to emulate the more sophisticated audience who want a more realistic RC heli flying experience, sought to get close to how a real helicopter operates without all the complexity. To do this, they have to scale up the model size.

Typically, the hobby grade 4-channel birds are 18-24 inches in length, and single main rotor. (There are exceptions, like the E-Flite Blade series, which are only 8 inches long) THESE ARE NOT TOYS. You can hurt someone if you crash it into someone. Both the blades and the body can cut people. Don't fly these indoors unless it's a BIG space, like a gymnasium. They generally use 2.4 GHz radio control and thus the range is increase to 80 ft or so.

A real helicopter dynamically adjust the "pitch" (or how much the blade cuts through the air) of the main rotor and use that to control which way to fly. To fly forward, the blades are adjusted so the "rear half" of the rotor disc produce more lift (higher pitch) than the front half. To fly to the left without turning, the "right half" fo the rotor disc is adjusted to have more lift than the left. And so on.

This sort of fine control is not possible with a 4-channel bird, as their main rotor is "fixed pitch", and does not change pitch like a real helicopter. Instead, they have other tricks to allow them to achieve sideslip: by moving the rotor axis itself through a set of servos right on the main rotor. By tilting the main rotor slightly the bird can go forward backward and sideslip left and right.

There is another type of 4-channel hobby bird, the co-axial type, with two main rotors that are counter-rotating (one clockwise, the other counter-clockwise). These are very stable as both rotors act as "gyros". to stablize the craft, but as a result have a very different flight charactertistic than the fixed-pitch single-main-rotor 4 channel hobby birds, as they don't have a tail rotor.

These 4-channel birds are hobby grade and will cost anywhere from $50-200. However, these are carefully built pieces with all the parts replaceable and upgradeable. Servos, motors, rotors, gyros, antenna, even battery pack. A good one is about $120.

Should you go this route, it would be wise to get a tool kit, a training gear landing skid, quite a few replacement parts, extra battery and charger, and perhaps a PC "trainer" where you practice flying on a PC before you try it with your hobby RC heli. One link is provided above (only about $20 or so).

Pros: more maneuverability, lots of replacement parts are available for repairs

Cons: 4 degrees of freedom means more training is needed, and damage will hurt your wallet more, still not full maneuverability

Look for: metal frame, metal rotor mechanism, 2.4 GHz radio frequency control, spectrum-spectrum anti-jam, gyro stabilization assistance, available replacement parts

The "professional" Hobby RC helis features full 6-channel control, which means full 6-degrees of freedom. These helis costs up to 1000 dollars, and is capable of full acrobatic maneuvers, including flying upside down, barrel rolls, and more. The high-end ones will be using nitro fuel instead of just regular batteries.

These 6-channel pro hobby birds emulate a real helicopter's rotor mechanism by allowing individual main rotor blades to change their pitch (pushing more or less air) as they rotate. The rotor mechanism is going to be far more complex than the toy models, but the result is far more maneuverability and true helicopter flight.

Older generatations of the birds have an additional 'flybar' to act as a balancer / gyro though the latest generation is flybar-less. Also, instead of almost always 2-bade main rotor, some 3-bladed designs have appeared, making them looking more and more like a real helicopter instead of just an approximation. You can see the eSky HoneyBee CT video below, which is a tri-blade flybar-less design. It looks like a helicopter static model, not an RC heli, yet it flies.

The performance limits between a 4-channel and a 6-channel hobby heli is night and day. Here's what a 6-channel bird can do. Keep in mind this is probably a $750 bird with customized parts, nitro-engine, and so on, but it's still a bird you can buy off the shelf. In this video, you'll witness this heli doing barrel rolls, switch between right-side up and upside down, loop, Immelman climb and dive, nose-up sideways flight, and much more. Watch, and be amazed.

The pro hobby 6-channel RC heli requires a bit of experience, and is not something you should jump in feet first. Though I do recommend you visit Xheli.com, which has a lot of tutorial videos, tweaking and tuning tips, and such.

There is even a few RC helis on the market that can be switched between 4- and 6-channel operations.

In general, I do not recommend buying any of the "toy" micro-sized RC helis, even if they are 4 channels. They are okay for indoor fun, maybe buzz the cat or dog for your amusement, but no more. Once they crash a few times they are pretty much done for. The motors are not expected to last for too long, and battery with constant charging and discharging wears down quickly as well. If you do get one in this category, buy one of the good ones, like E-Flite, not those drugstore specials.

For proper hobby flying you should get a "mini" or "mid-sized" 4-channel RC heli as your starter heli. You can learn how to fly with one of those properly, and transition later to a proper 6-channel RC heli. You will pay more to start, but with plenty of parts available you can maintain it and keep it running without buying replacement helis every few months.

The best way to start, in my opinion, is buy that eSky training kit for about $25, which gets you a USB RC controller replica so you can pratice controlling an RC helicopter or aircraft and crash as much as you want without hurting one wallet one bit. Once you're sure you can control such a beast, then go ahead and buy the real thing.

In conclusion, I hope you have found this quick guide to RC helicopters helpful in reaching a decision for your own purchases, or just for your personal amusement. Have fun out there.