Get it bought, I'll do this from the top:
Twin rotor heli's are called co-axial or contra rotating, they are superb starter heli's as they have two sets of rotor blades, one spins clockwise the other anti-clockwise, thus eliminating the need for a tail rotor in order to control yaw or left and right steering, to turn left the anti clockwise rotors simply spin slower so that the forces from the clockwise rotors force the body to the left and vice versa.
They are whats called fixed pitch (FP) which means the rotor blades never move apart from spinning round and are incredibly stable and come in anything from 2 - 4 channel, 2ch is simple and the most basic but also the most boring, Channel 1 (CH1) would be altitude control, as the blades are set at a fixed pitch the simplicity is the more throttle you give it, the higher it goes.
CH2 would be rudder or yaw control.
3 channel heli's are the same as above but CH3 is usually forward and rearward movement/cyclic pitch enabling you to fly circuits.
4 channel adds roll (cyclic pitch)/sideways movement allowing you to strafe from side to side.
Stay away from anything claiming to be 3.5 channel or similar, this is just cheap sh*t and isn't worth the money they claim to cost, there is no such thing as .5 or half a channel its always whole numbers like 2, 3 or 4, go for E-Flite for co-ax heli's and you won't go wrong, they're cost effective, come on 2.4ghz complete with batteries and a charger and they have an excellent re-sale value.
With all of the heli's above if you panic you can let go of everything except for the throttle and the heli will come to a standstill in the air and just sit in one place, let go of the throttle and it hits the deck.
The Blade SR120 mentioned above is a 4 channel FP but it has a single rotor set and a functioning tail rotor and is the best step into the world of single rotor heli's, although I can fly bigger I would love one for use in the house and there are same brand but cheaper alternatives like the Mcx (contra) and Msr, now in this case as the rotors spin this causes the body to spin in the opposite direction which is why they have a tail rotor which pushes against the natural spin causing the body to remain straight.
You can also get what is called a 'notar' this is only found on turbine and real heli's - also turbine - they have a single rotor set but no tail rotor, they have a sort of 'cap' on the tail with a slit in it, this allows air from the turbine to escape through the slit under pressure causing the same effect as a tail rotor and it rotates to allow for left and right propulsion.
Single rotor heli's act like an astronaut in space, which is once they move unless there is another input or counteracting force then the heli will theoretically keep travelling in that direction for eternity, obviously batteries, fuel, wind, buildings etc etc come into play but not for this explanation, so basically if you panic and let go of everything your heli will continue to fly itself until you take control or it crashes which is usually the case.
Now I fly 6CH collective pitch (CP) helicopters which means that whilst spinning round I can also rotate the blades by entering 'idle up' mode creating positive and negative pitch which changes the direction that the wind is pushed by the rotors depending on where my throttle stick is positioned (when in idle up your throttle becomes pitch control whilst the revs you controlled before remain fixed at a set rate) meaning that when I'm showing off I can fly upside down (Idle up mode contains throttle and pitch curves and is a long ass process to explain, I will explain it to anyone that wants to know about it though) my helicopter is a Blade 400 - there is a pic in the guide - and is an intermediate heli although some pilots will tell you its a good beginner heli.
6ch gets complicated so I have sourced a guide to explain it a little:
http://en.wikipedia.org/wiki/Radio-controlled_helicopter.
Click this link for a demo of what you can do:
This kid is 7 and has been flying since he could walk, I'm no where near as good as this kid but I can do some of it, he is also using a Nitro (NitroMethane) which can be flown 6 Channel if you set up Throttle and Pitch curves but are usually classed as 7 Channel as they use something called a governor.
There are petrol models available which are known as 'Gassers' but they operate in the same way as nitro.
The inner pic of the transmitter (TX) shows you how quick you have to be with these things but also shows you how they operate with throttle/rotor pitch and rudder on the left stick and cyclic or forward, backward, roll left and right on the right stick.
As a general guide to get this good takes YEARS of daily practice, if you are thinking of getting into this hobby you need to be aware of some stone cast rules:
1. It is a VERY expensive hobby
2. When you crash and you WILL crash your looking at roughly a £30 repair bill for a light ding and the first crash makes or breaks it for you as a hobby with 90% being the latter.
3. It takes WEEKS if not MONTHS just to learn how to hover tail in and once you can tail hover you then have to learn all orientations meaning side on, nose on etc again this takes AGES but will eventually just click.
4. Buy a simulator, a decent one (Phoenix) will set you back around £80 but it will save you thousands in the long run.
5. If possible find a local club, get loads of advice and if you can afford it take flying lessons.
6. Always buy reputable GHZ like Futaba or Spektrum, MHZ glitches and causes no end of trouble.
7. Dont forget your insurance, yes thats right you have to have it, imagine you buying a £300 heli kit and spooling up in your driveway cause your itching to get it flying and then you crash into your neighbours Porsche facing massive repair bills to the car and then to your heli, most clubs are run by the BMFA (British Model Flying Assoc.) or are affiliated and they require their insurance as standard but the cost of £29 yearly (Jan 1st - Dec 31st) covers you wherever you fly in the UK, whenever you fly upto the cost of £10m, yes ten million pounds, now hitting that Porsche doesn't seem so bad does it! However you must check with your local council as a lot of councils prohibit the use of RC in their local parks etc.
8. Have a friend with you as a spotter, you can't see whats going on around you if your flying.
9. Choose which route you wish to go, most start electric then progress into nitro mainly because its the 'norm' but as you grow with your heli so does your spares/toolbox (flightbox) making nitro not so expensive, take into account your own individual circumstances, within reason you can fly electric pretty much anywhere, nitro has to be flown at specific sites/fields costing £50+ a year because of noise and pollution and you need a bunch of extra kit like starters, glow plugs, 12v battery, fuel, massive car to transport the heli in etc etc.
10. Now you have learned your lesson with the Porsche this is the most important rule of all, NEVER EVER show off to the point where you can endanger any person, apart from being prosecuted regardless of insurance, rotor blades have a tip speed of about 200mph which means they WILL cut through whatever they hit, I have seen a video on Youtube (and its still on there) of a young lad that thought he was clever until the rotor cut through his calf.
Dogs in particular have a tendency to chase Heli's, make sure you or your spotter warn dog walkers if you are coming in to land, taking off not really a problem as you can stop but landing may be due to damage, loss of fuel or depleted battery etc, I have heard many stories of walkers not listening to pilots of bigger heli's and so dog and machine met and then walker takes dog home in a bin liner.
I fly at a local field and only take off/land when safe to do so and most dog walkers will go about their day after the dog has said hello but there is always one that think they know better.
Edit: I also have a 4ch plane called a Cap232 with a 3ft wing span, this is a 3d plane meaning it will do everything that the heli in the vid will do within reason, Youtube it and you will find someone showing its capabilities, mine is up for grabs complete minus Tx so if you wanna bargain gimme a shout.
