When you are looking at RC helicopters on line, you will no doubt open the list of specifications to compare different models. This is where a lot of pilots start scratching their heads because, whilst some of the terms are familiar from what they’ve read about electric helicopters, others will read like a physics text book.

Don’t worry. A lot of the more technical info is irrelevant unless you need to replace a component. What is more important is understanding the importance of familiar terms, such as size and weight.

Most pilots want to buy the biggest rotor size their pockets can manage. However, weight is also important. Often ignored, this is something you must consider when buying RC electric helicopters, especially collective pitch, advanced models like the ESky Belt.

The more specs an RC chopper has, the closer it is to the real thing when in fly mode. You may think you still have a way to go before you can start taking passengers. However, many passenger helicopter pilots swear that RC electric helicopters are harder to fly than the real thing!

Why? Because of their lightness. RC helicopters that are very light for their rotor span are notoriously difficult to control. Whilst many pilots like the increased sensitivity and 3D possibilities that this brings, there can be too much of a good thing. To fly well, RC helicopters must have a decent sized “payload”, offset with a large enough engine to pull it off the ground and make it nippy in the air.

A good guide, with RC electric helicopters, is to compare the main blade diameter in mm with the payload weight in grams. The ESky belt has a 680 mm blade diameter – almost equal to its nose-to-tail length of 640 mm. The total weight, including battery, is 670g.

Anyone can see these are extremely well balanced RC helicopters; the lift achieved by 680mm rotors is well up to the task of lifting 0.7 kg of helicopter off the ground. Much of this bulk is down to such meaty inclusions as the 450 brushless motor, 25A ESC and11.1V LiPo battery pack.

The best made RC electric helicopters always optimise lift by balancing weight with power. If you are upgrading your existing RC helicopters, rather than buying a more expensive upgrade new, it is something to keep in mind. Make sure your rotor can easily balance your payload – and vice versa.

When the blades of RC helicopters rotate, the body wants to spin in the opposite direction. This force is called torque. To counteract it, you produce sideways thrust with a second rotor on the tail. RC Electric Helicopters may have either a clockwise or counter-clockwise rotating main blade. Depending on this, the tail rotor will be set either on the right or the left.

To control RC Helicopters, both rotors must be adjustable. This is done via the controls on the transmitter, or Tx. This sends signals to the receiver, or Rx, located on the helicopter. This then sends electronic signals to the various components, which translate them into electronic inputs to various mechanical components – for example, the servos or speed regulator on the motor (ESC)

Fixed wing planes have airfoils. The main rotor blades of radio control helicopters are shaped like long, thin airfoils and they work the same way. Increasing or decreasing the angle of attack - i.e. the amount of blade in contact with the air stream – will alter the speed the craft is moving by altering how it “slices” through the air. Lifting the blade increases the angle of attack, lowering it decreases it.

The swashplate varies the angle of attack via a system of linkages to the fly bar and main blade grips, and by servos that alter its plane. Altering the plane of the swashplate alters the tilt of the rotor disc, and thus the angle of attack of the blades. RC Helicopters will follow the path of least resistance, thus varying the angle of attack in different directions (by tilting the rotor disc) will cause the helicopter to follow that direction – this is the cyclic phenomenon.

To generate lift the angle of attack must be increased across the whole rotor disc – or the speed of the blades increased to such a point that lift is achieved independently of this. In collective pitch RC helicopters, lift is achieved by the entire swashplate moving upwards; this allows the angle of attack of the rotor blades to increase until the entire heli lifts off the ground.

In the air, collective and cyclic pitch can be employed together or independently. The tail rotor pitch can also be altered. RC helicopters with collective pitch and belt-driven tails are, as near as dammit, tiny models of the real thing. They are capable of practically anything.

With these electric helicopters, you have true mastery of the sky.

In electric helicopters, yaw control (the swing of the tail end) is achieved by varying either the rudder pitch or its speed. The first method depends on a complicated belt and servo mechanism, whilst the second uses a simple variable speed motor connected to a fixed pitch rotor.

The belt-driven tail rotor is generally considered the superior of the two. However, motor-driven tails are improving all the time.

In both cases, a gyro is often used to improve performance, by negating outside influences such as crosswinds. Considered essential for outdoors flying, the gyro is a piezo-electric device installed between the receiver and the tail rotor. Its job is to detect unwanted vibrations or movement, and adjust the tail rotor speed accordingly so it matches the torque strength of the main rotor.

A standard Piezo gyro only responds to conditions at that exact moment, and does not take into account the overall direction the pilot wishes to fly. Pilots performing intricate 3D manoeuvres in breezy conditions often find themselves “battling” the gyro, although the gyro sensitivity can be altered to suit flying conditions.

Therefore, Heading Hold Gyros are often used in RC Electric Helicopters. These are more advanced, and require the pilot to input data detailing the direction he wants to go. The HHG performs complex calculations to keep the helicopter to that heading, which is memorised until the next input is made. Again the sensitivity is fully adjustable, depending on the type of flying being done, and the prevailing weather conditions.

Are Heading Hold Gyros a better choice for Electric Helicopters? Bearing in mind the control they give, the answer has to be yes. However, they are complicated to get to grips with, and outside the scope of most novice pilots. Even up to intermediate level, standard piezo gyros work just fine.

Crawley, West Sussex, isn’t renowned for its RC model shops or flying fields. However, pilots of radio control helicopters would have had a treat, had they been at ASDA recently.

Because in the car park was a veteran RAF helicopter, “Zulu.” Now being restored by an enthusiastic gang of volunteers, she last saw service in the Falklands, flying wounded personnel for the Medical Corps.

The people restoring her have more than a passing interest in radio control helicopters. Apparently, the old bird has got quite a packed schedule this summer, making guest appearances at various heli club meets and air shows across the country.

She may well meet a few old friends. RC Helicopters attract Air Force personnel the way model boats attract retired sea captains. In fact, you could say that the RAF has an entire squadron of radio control helicopters, all to themselves…

The RAF Model Aircraft Association was founded in 1949, when the RAF recognised model aircraft flying as an official RAF sport. RAF personnel had been closely involved with the BMFA (then called the Society of Model Aeronautical Engineers) since their early days, so it wasn’t before time.

Undoubtedly, modern electric helicopters owe their existence to those early pioneers in the SMAE and the RAF. Next time you fly, it’s worth remembering that names like Frank Whittle and Thomas Sopwith were instrumental in establishing the concepts from which rotational flight model aircraft (that’s RC Helicopters, to you and me) developed.

The website is well worth a look – it’s totally unlike the usual model club site. Your chest puffs out with pride just looking at the handsome RAF logo, let alone reading the history pages. And there are some fascinating snap shots of vintage model aircraft from yesteryear to browse through, as well.

Although RC Helicopters aren’t depicted in the photographs (mainly because the photos predate their existence) this doesn’t mean they aren’t flown. In fact, the club has an active radio control helicopters section, and “loans” its experts to various civilian events. All RC helicopters are welcome - the only stipulation is that you are either current or former RAF personnel.

RAF MAA shows are open to the public. However, if you think your prowess with electric helicopters will sneak you in by the back door – think again. A Wing Commander holds the post of Chairman, with various other air ranks presiding over the committee. Squadron Leader Rogers is the current enrolment secretary, so it’s unlikely your weekly stint with the Air Cadets will be enough to earn you membership, no matter how shiny your BMFA badge is.

The FAI has allowed the competitive flying of Electric Helicopters to become standardised across much of the world, with the flying clubs of individual countries following FIA guidelines wherever possible.

This means that, although each country will have local laws governing the flying of RC Helicopters, the overall schedules will be the same. This makes competing in tournaments abroad a relatively easy affair. The UK’s BMFA scheduling is very similar to that of America’s AMA, for example.

Because of this, there are many benefits to holding BMFA/FAI membership and insurance if you take your electric helicopters on holiday with you. Most foreign heli clubs will recognise BMFA standards, and be happy for you to join in, either as a recreational flier or at competitive level.

This is never clearer than “across the pond.” The AMA and BMFA seem to be joined at the hip, where RC electric helicopters are concerned. Just like the UK, the AMA has 4 competition classes, ranging from Schedule 1 (equivalent to Sportsman A class) to F3C – the FAI classification for aerobatic RC Helicopters, which is the same the world over.

Like the BMFA classes, the American schedules get progressively harder as you go up the ranks. Schedule 1 covers basic tail-in and sideways hovering manoeuvres, pirouettes, stall turns and rolls, all performed as single components within a very simple pattern framework. This is a broad schedule that includes all the BMFA Sportsman classes from A to Z.

Schedule 2 covers more complex aerobatics, including multiple rolls, loops, 540 degree stall turns and vertical lines. For Radio Control Helicopters to be in this class, pilots must be able to accurately hover within 0.5 M of a set point.

Bearing in mind a lot of the US competitions take place in tornado country, this isn’t nearly as easy as it sounds.

Finally, there is Schedule 3, equivalent to UK Masters tournaments, after which it’s FAI all the way.
Americans love electric helicopters. As well as hosting this year’s F3C World Championships, there are heli clubs in every state and county. Events range from serious Schedule 3 tournaments to Fun Fly Hog Roasts.
So remember: if you’re fly driving to Florida this year, pack a T-Rex along with your trunks!

RC electric helicopters with a single rotor (i.e. fixed and collective pitch, rather than co-axial) have a rear rotor to generate sideways thrust. To make the fuselage of electric helicopters remain straight, the rear rotor thrust must equal the torque from the main rotor. Adjusting the rear end thrust causes yaw, or movement of the tail, right or left.

The rear rotor is either driven by a separate motor (motor driven) or via a belt from the main motor (belt driven). The latter method is more complex, and therefore more expensive, but is generally preferred. Let’s see why.

Electric helicopters can have fixed or variable pitch tail rotors. With variable pitch tail rotors the pitch, or thrust, of the tail rotor is varied by commands from the receiver to the tail servos. Power to the rotor comes via a belt from the main motor.

This means the power to both tail and main rotor is constantly balanced, and yaw is controlled by servo command. It is a lot more complicated than this, but that is basically what happens.

With RC electric helicopters utilising a tail motor, the rotor is (generally) of fixed pitch design. There is no complicated gearing mechanism, pitch slider or servo. Thrust is varied by the speed of the motor alone.

Because the tail rotors on RC helicopters are smaller than the main rotors, they must have a much higher RPM for the tail thrust to balance the main blade torque. Even when negative yaw is applied (the tail thrust set lower than the main torque) the RPM is still very high.

However, the size and weight restrictions of electric helicopters mean any tail motor used must be much smaller and lighter than the main motor. If it is too heavy, it will upset the helicopter’s centre of gravity.

Since the motor is underpowered for the work it has to do, it is prone to burning out quickly. Also, lack of pitch control means that, just as with fixed pitch main blades, the craft is less responsive. There is always a lag before it responds to pilot commands, making it hard to fly during bad weather conditions.

Modern refinements, such as brushless tail motors, have improved tail-motor driven Electric Helicopters. However, advanced pilots generally reckon belt-driven as the best RC Electric Helicopters you can get.

Makers of RC electric helicopters are constantly upgrading the components of even their most basic craft, in an effort to outdo the competition. This makes life confusing for newcomers to electric helicopters who are just getting to grips with the basics.

For example, what is a Heading Hold Gyro - and how does it differ from a Piezo-Electric one? It helps if you understand the job a gyro has to do; which means understanding how tail rotors work.

Non co-axial RC Helicopters have a tail rotor to counteract the torque, or body spin, that the main blades produce. The tail rotor must be adjustable, and this is done by changing its pitch or motor speed.

Adjusting the tail rotor (pitch or RPM) of Electric Helicopters allows pilots to apply yaw; in other words, to allow rotation of the craft about the tail axis. Say you’re heading in a westerly direction, but then want to fly south. Adjusting the yaw allows the heli to pivot and face in the new direction. However, there are many other applications for 3D flying and, evidently, the best RC electric helicopters are the ones with the best tail control…

Tail rotors are of two main designs:

• Fixed pitch motor driven. These have their own independent motor. Rotor adjustments are made by the pilot adjusting the ESC (electronic speed controller) of this motor.
• Variable pitch belt-driven. The rotor pitch is altered via servos controlled by the pilot. Power is supplied via a belt and gearing system connected to the main motor.

Both motor driven and belt driven Electric Helicopters employ tail gyros. These help balance the chopper by detecting outside forces, e.g. directional wind changes, and counterbalancing them. Only the most basic, indoor RC Helicopters lack a gyro.

Typically, a tail gyro will be of piezoelectric design. This means it generates an electrical signal in response to vibratory or other unwanted tail movement, and adjusts the rotor inputs accordingly. Thus, RC Helicopters with built-in gyros will respond as the pilot wants them to, unaffected by outside influences. The sensitivity of the gyro can be adjusted depending on the pilot’s ability or the flying conditions.

Heading Hold/Lock Gyros are a more advanced form of gyro with a “memory” function. A basic PEG works on each individual tail fluctuation. A Heading Lock memorises all the varying rotor speeds and then applies the best solution overall. They are excellent for bad weather flying, or for Electric Helicopters that are used in advanced 3D aerobatics.