What are some good helicopters to consider?
There are several good helicopters on the market. It's a bit like Ford people versus BMW people: different people develop preferences for different helis. Good ones to learn on include the Hirobo Shuttle, Kyosho Concept .30, and Thunder Tiger Raptor. An excellent although somewhat more advanced heli is the X-Cell .40. Hang out at the flying field for an afternoon or two, and see what we are flying. Heres a small list of Helis flown at our field; Concept 30/60, Raptor, Shuttles and Ergo`s.

Price to get going?
The helicopter itself will cost from £150 to $300 for a good starter heli. A radio will cost £200 to £450 or so. Gyro is about £70. Engine is about £100. Starter box, starter battery, etc. will probably be at least another £80.

What are some good books?
An encyclopedic book is the one by Ray Hostetler. This book goes into great detail on all topics, and is a book to grow into. Ray's book mixes beginner info and info necessary only for advanced pilots, and consequently can be a bit overwhelming at first. There's a lot of stuff in there that you won't need to delve into for quite a while. I would recommend getting both of these books.

What accessories should I get?
There are a million accessories that you can buy. There are a relative few that are indispensible, or almost so. I'd put the following items on the short list: a prop balancer, a pitch gauge, a pair of ball link pliers, and a receiver battery tester. You will need a standard assortment of tools such as needle nose pliers, screw drivers, hex wrenches, etc. You'll also need a starter and starter battery.

What about electrics?
There are a couple of pretty good electric helis on the market. One is made by Kyosho (the Concept EP), and one is made by Ikaris (Eco 8/16). These machines are small, light, delicate, and squirrely. Not the thing to try to learn on. They are more novelty items for experienced R/C heli pilots.

Controls on a heli

What is cyclic? Collective?
On most R/C helis (and full-scale helis for that matter), the main blades can change their (so-called) pitch angle. What this means is that if you sit the heli on a table and look at the tip of one of the main blades, the chordline of the blade can be tilted through a range of angles by the servos. In this sense, the rotor disk of a heli is a bit like a variable-pitch prop on an airplane. If the heli is hovering and you wish to make it climb straight up, you increase the pitch of the main blades, and increase the throttle so that the engine can overcome the increased drag and keep the blades turning at the same speed. The increased blade pitch results in more lift, and so the heli climbs. (With R/C helis, unlike R/C airplanes, engine RPM's are supposed to stay the same over (most of) the throttle range. At high throttle the engine puts out more power, but there is a corresponding increase in the load on the engine due to increased main rotor blade pitch, and so the engine stays at the same RPM's.) This overall increase in pitch that makes the heli climb is called collective control.
To get the heli to pitch forward or back, and to roll left and right, there are controls that are analogous to airplane elevators and ailerons. These controls are refered to as cyclic controls. The idea is to set up asymmetric lift on the rotor disk. (This is similar to what ailerons do to an airplane-one wing can be made to generate more lift than the other, and so the airplane rolls.) If there's asymmetric lift on the rotor disk, the plane of rotation of the rotor disk is going to change. For instance, the rotor disk (and the heli that is attached to it) might go a bit nose-down. In that case, the heli will transition out of a hover and start flying forward. Similarly, the heli can be made to lean back (nose-high), left, right, or any combination of these. The way this asymmetric lift is set up is to vary the pitch of each blade as it goes around. For instance, say you push forward on the cyclic control stick (the right one on your transmitter, which does the same thing as an aileron/elevator control stick on an airplane radio). This will make the blade pitch down as it travels through the forward-moving part of the rotor disk (usually the left side of the rotor disk), and it will make the blade pitch up as it travels through the backward-moving part of the rotor disk (usually the right side of the rotor disk).

What is gyroscopic precession?
This is a counter-intuitive aspect of helicopters, that even many advanced pilots don't clearly understand. In order to get the helicopter's rotor disk to tilt (for example) downward at the front, you increase the lift on the right side of the rotor disk and decrease the lift on the left side of the rotor disk. (This is assuming the standard clockwise main rotor rotation.) To see why this is so, consider the following example. If the heli is in a nose-down attitude, the forward moving blade travels downhill, and the aft-moving blade travels uphill. The blades travel level at the front and back. To get a hovering heli to go into a nose-down attitude, you need to encourage the forward-moving blade to start going downhill and the aft-moving blade to start going uphill. Hence, pushing the cyclic stick forward causes lift to be killed on the forward-moving (left) part of the rotor disk and increased on the aft-moving (right) part of the rotor disk.

What do the servos control?
There are usually five servos on an R/C heli. One controls throttle, one controls collective, one controls fore-aft cyclic (analogous to elevator), one controls left-right cyclic (analogous to aileron), and one controls tail rotor pitch (analogous to rudder).

What is the use of gyros and how do they help?
The gyro is positioned so that it senses yaw. It then feeds small inputs to the tail rotor servo to counter the yaw that it detects. This keeps the helicopter from yawing to the left and right when you don't want it to. Left-right movement of the left stick also supplies input to the tail rotor servo; so you and the gyro are both giving control inputs to the tail. A gyro is a MUST. It's probably not an exaggeration to say that gyro-based stabilization of the tail rotor made R/C heli flying feasible. It is possible to fly an R/C heli without a gyro, and it's also possible to juggle seven balls. It's just darn hard! Furthermore, it's definitely not something you want to try tackling when you're just getting started. Without a gyro, the heli can begin to whip around wildly as soon as the skids leave the ground. The heli will do a 180-degree turn and you're looking at an angry helicopter coming right at you before you know what happened. Definitely not something for a beginner to tackle.

How about fixed-pitch versus collective helis?
Helicopters with collective are now inexpensive and reliable. Every reasonable modern heli, from beginner-trainers up to FAI world-beaters, has collective. In a fixed-pitch heli, lift is controlled by varying engine RPM, just as in an airplane. This is an outmoded technology, and you will outgrow such a heli very soon. Virtually no aerobatics, no auto-rotation (if the engine quits at altitude, the heli becomes a brick), not as much fun.

Radios

How many channels do you need to control a heli and why?
You need five channels to control a heli. You need one each to control pitch, roll, and yaw. You need one to control throttle, and you need one to control collective. You might think that one servo could control both throttle and collective, since they are related. There are several reasons this wouldn't work, however. The main rotor disk of a heli is huge and generates a correspondingly huge amount of drag compared to an airplane prop. (If you think of the heli rotor disk as a big propellor, its actually pretty amazing that a tiny little .32 engine can turn it at all. There's about a 10:1 gear down from the engine to the main rotor, which makes it possible for the engine to turn the main rotor.) So, you have to have fairly fine control over the relationship between the collective pitch (and corresponding drag) and the throttle setting. If you get it wrong, the engine bogs badly or races wildly. Also, auto-rotation is an important maneuver, and this entails control of collective pitch while the throttle is set to idle. Finally, for inverted flight you want to have full throttle both at maximum up collective and maximum down collective.

What are the radio options?
Pitch curves and throttle curves: You can adjust the amount of servo travel at 0% stick, 25%, 50%, 75%, and 100%, both for throttle servo and collective servo. This feature is a must.
Throttle hold: Flip this switch to practice auto-rotation; the throttle is reduced to idle. All the other controls still work normally.
Idle up: This is an alternate mode, usually used for aerobatics. You can set throttle and pitch curves, mixes, etc., and change over to the different setup at altitude or whenever.
Programmable mixing: This neat feature lets you establish a relationship between channels. One channel is designated as the input or master channel. As the master channel varies, it causes small changes to the output channel. This is an advanced feature.
Revolution mixing: This feature causes increases in tail rotor as throttle and pitch increase. This is useful to compensate for the increased torque the engine produces. I feel that this is a somewhat over-rated feature, and that it only really comes into its own when you're doing aerobatics. Even then, a programmable mix may be better.
Electronic trim adjustment: similar to and augments mechanical trim
End point travel adjustment: sets where servos go at max stick displacement
Exponential: can be used to make cyclic less sensitive in midrange.

Can I use my airplane radio?
It is possible to control a helicopter with a 4-channel airplane radio. You can master hovering and move into elementary forward flight this way. For anything beyond that, you will need a helicopter radio. If you do try to use a 4-channel airplane radio, build a Y-connector, and control two separate servos (collective and throttle) off the throttle channel. Then adjust control arms to get a form of mechanical throttle and pitch curve adjustment. It's not too hard to set a heli up so that it will hover tolerably well at mid-stick this way, and you can contrive to increase lift above mid-stick and lose lift below mid-stick. But why bother, make it easy on yourself and get a heli radio in the first place.

Flying

What's the deal on auto-rotation?
If a heli's engine quits in flight or you simulate this by going to throttle hold mode, it is still possible to glide the helicopter down safely. As the helicopter descends, the wind flows up through the rotor disk from below. At a low or negative collective pitch setting, the wind flowing up through the rotor disk keeps the blades spinning. Heli blades usually have lead weights epoxied into the tips, so as the blades spin they build up a fair amount of rotational inertia. When you are near the ground and ready to land, you add in collective to increase lift, and the inertia maintains head speed sufficient to execute a controlled landing. In theory. ;-) Auto-rotative glides and landings are beautiful to watch. A helicopter can sustain as much as a 4:1 glide ratio in auto-rotation.

What about aerobatics?
Helis can do awesome aerobatics: loops, rolls, pirouettes, you name it. My personal favorite is inverted flight. If looks 'way cool to see a helicopter hovering inverted right above the grass. I've seen guys do aerobatic routines flying the whole thing BACKWARD. With a helicopter you have unbelievable versatility.

How high do they fly? How fast do they go?
Helicopters can go so high they are out of sight. Being able see the thing in order to control it is the only limit on how high they can fly. R/C helis can go 60-80 MPH or more.