In nitro or gas powered RC helicopters, the C of G (centre of gravity) changes as the gas is used up. Pilots generally have to check their C of G when the fuel cell is about half empty.

Electric helicopters don’t have this problem. However, they are still very sensitive to changes in weight, which can disrupt their balance and affect flying.

This can happen if a component is upgraded to one of a lighter weight e.g. a plastic tail boom is replaced with a carbon fibre one, or one that is heavier e.g. a battery upgrade to a more powerful cell size. The C of G can also be disrupted if parts move position e.g. the battery may have worked loose from its housing.

There are two ways of checking the C of G on RC Helicopters. In flight, they can be observed in hover mode, i.e. checked for tilting. At the bench, the easiest way is to pick the heli up by the flybar. If the nose and tail are level, the helicopter is balanced.

The C of G should be exactly at, or slightly forward of the main rotor mast. If it’s too far forward the nose will tip downwards. The reverse will happen if it’s too far back.

Many people prefer a bit of forward tilt, as it makes the helicopter fly faster when going forwards. However, beginners are best off with the nose and tail as level as possible. Leave the balancing acts for when you are an advanced flier.

So, if there is an exaggerated tilt to your aircraft, either fore or aft, how do you correct it?

The C of G in RC Electric Helicopters is normally governed by the position of the battery pack, so the easiest way is to adjust the position of the battery by loosening it in its housing and sliding it to a new position before retightening.

If this is not possible, try adding a small amount of plasticine or a paper clip under the rotor, or on the nose or tail. Experiment until you get the best results. Remember that any weight added to Electric Helicopters – especially micro craft - will affect their speed and flight time.

All mechanisms - not just RC Helicopters - have an optimum centre of gravity (C of G or CG). To understand the subject properly you have to go back to the days of high school physics; fulcrums and pivot points. Simply put, the C of G is the balance point, where the weight is equal on both sides.

In consistently weighted objects, the C of G is in the centre. However, RC helicopters are unequally balanced and therefore the C of G is towards the front. This was all worked out at the design stage, with the rotor mast being positioned for optimum balance – this is where the C of G will be.

A little leeway is allowed. For most electric helicopters the C of G is at the centre of the rotor mast. However, on some models – especially if they have been modified - it will be just in front of this point.
The C of G is practically the last thing to be checked before flying a kit built helicopter. However, it is a good thing to learn even if you only plan to fly RTF Electric Helicopters. If you upgrade, have a crash or even add a few ‘embellishments’ to your favourite bird, the C of G may alter. Occasionally, it can even happen in transit.

Checking is easy. First, make absolutely sure that every one of the rotor and RC components is correctly balanced. Also check that the battery and engine are firmly housed and correctly anchored. Now take off and hover. The tail to nose line should be parallel to the ground. If it isn’t, then the C of G needs adjustment.

When checking the swash plate alignment on RC Helicopters, it is best to choose the ‘C- shaped’ swash tool. These allow you to slide the tool over the rotor shaft without dismantling the head. Since you may well have to adjust the swash whilst out on the field, this is by far the easiest and best kind to use.

This tool is invaluable for checking that the swash plate remains level, and gives an accurate response, throughout its entire range. It is common to discover discrepancies in travel, especially in Radio Control Helicopters that are equipped with CCPM (Cyclic-collective Pitch mechanisms). This can seriously disrupt matters when flying at the extreme cyclic pitch ranges.

Instructions

First, check that the main rotor shaft is aligned 100% vertically. Place the tool on any surface of the helicopter that is 90 degrees perpendicular to the main shaft, and check the helicopter itself is completely level to the ground by checking against the spirit levels. Adjust the helicopter using blocks if need be.
Now slide the tool on top of the swash plate. This may be difficult on some Electric Helicopters, in which case you may have to dismantle the head assembly.

Switch the RC on, and check the collective is set at the mid-range point. Now look at the spirit level indicators on the levelling tool. If they show the plate isn’t level, adjust the linkages until it is.
Electric helicopters can be ‘trimmed’ to allow the best response in flight – remember to take this into account when setting your swash plate against your transmitter, or you might make things worse.

Of all the RC Electric Helicopters released in recent years, T-Rex has created the biggest buzz among Nitro and electric owners alike. This is because Align, already famous for their superb Nitro 600 RC Helicopters, have now produced an identical electric version to their Nitro 600. Identical in looks and performance, it has crossed the divide from gas to electric – and revolutionised the industry.

Not so long ago, Electric Helicopters were looked down on by the pro flying crowd, who perceived them as undersized and underpowered. They were okay as indoor toys, but to fly Radio Control Helicopters properly you had to have fuel bottles, glow plugs and lots of smoke and noise.

Even with the advent of LiPo batteries, advanced collective assembly and extended run times, the Nitro crowd would compare the 3D electric RCs to their own .50 Radio Control Helicopters and exclaim wistfully, “Yes, but they’re just not big enough,” before conceding that, in other ways, they were catching up fast – not least, in competitions.

Electric pilots, meanwhile, were grateful for the smaller size and responsiveness of their RC Electric Helicopters, and couldn’t be having with all that tricky gassing stuff – fun though it might be to fly something with a 1500mm rotor.

Align saw the need for a larger electric heli, saw how the Nitro T-Rex 600 was the most popular performer in its field - and created the T-Rex 600 Electric; every bit the equal of its Nitro powered cousin.
With superb, ‘Nitro Style’ performance combined with electric practicality, the T-Rex 600 is one of the few Electric Helicopters to be popular with Nitro and Electric pilots alike.

The 600 has a host of top quality standard features; like the alloy tail rotor with its triple action CNC bearings, and the powerful BL600 KV motor. The pitch holding, whether hovering or doing 3D aerobatics, is superb, and the powerful twin 22V batteries ensure it stays in the air.

In terms of workmanship, the T Rex 600 is a work of art. The rotor head, for example, is beautifully machined in black alloy, with precision built push-pull control linkages and triple bearings. With a host of other features, all designed to optimise the flying experience, it’s no wonder she regularly tops the reviews.

Align have already shown their worth with their Nitro range, and their smaller RC Electric Helicopters. Now they have crossed the divide, releasing the first electric heli that not only looks like a nitro – but flies like one too.

If you’re into building RC Electric Helicopters from kits, then why not build a few of the tools you need to make them fly? This is one of the easiest – you’ve probably got all the parts you need at home.

A level swash is essential – if it’s ‘off pitch’ all sorts of problems can happen with the cyclic and collective. Although it’s possible to buy swash plate tools quite cheaply, swash plates for Electric Helicopters come in so many shapes and sizes that it might be hard to track down the right one for you.

So why not make your own?

For this, you will need:

• A large metal or plastic washer, big enough to sit on the swash plate, without obscuring the ball links. Try hardware shops.
• Strong double sided tape.
• A tool to cut the washer – for metal, a rotary power tool is best, but be careful!
• 2 micro spirit levels. The best kind comes in a square plastic casing – perfect for this job.
• A bench spirit level.

TIPS: Most discount stores offer mini spirit levels at cheap prices which are perfect for the job. Also, you could have a go at cutting your own washer from flat plastic, if you can’t find one suitable for RC Helicopters.

First, you need to cut your washer into a ‘C’ shape. This means you can slide it over the swash plate without removing the head unit from the shaft. Not essential, but well worth doing.

Measure the diameter of your shaft and then cut a notch that’s just a little wider than this on the inner edge of the washer. About 1/5 of the total washer area.

Check the surface you’re working on is totally level, using the bench spirit level.

Place the mini-levels at 90 degree angles to each other on the washer, making sure they sit perfectly perpendicular to the bench.

Use the double sided tape to anchor them to the washer – you may have to resort to a glue gun at this point. You can, at a pinch, wrap electrical tape around the washer and mini levels. However, this will cause uneven ridges underneath the washer. Unless you can be absolutely certain the washer is still totally even throughout its 360 degrees, avoid this method.

And that’s it. To be fair, there are cheap swash plate tools available now for a wide range of RC Electric Helicopters. All the same, this is an excellent method and you will truly be able to say your kit built helicopter was custom made.

Too many people purchase their Radio Control Helicopters thinking they need never do more than learn how to fly it. When it starts to feel ‘less than perfect’ they decide it’s worn out, and go off to buy another one.

This is stupid. RC Helicopters need regular servicing to perform at their best. In this way they are just like the real thing. Would a pilot dump his ‘bird’, just because she’d started misfiring? Of course not!

Everyone should learn the basics of adjustments on their helicopter, in particular, the swash plate. The reasons are many.

Ready to fly Electric Helicopters are always thoroughly checked before shipping, to ensure they fly as well as possible. However, once they’ve been owned for a while, some of those settings will be out of alignment, either through crashes or just general wear and tear. The swash plate and its components get more wear and tear than any other part of the craft.

Adjustments have to be made after upgrading or replacing parts. The rotor head is where many of these upgrades take place. For example, you can replace plastic components with machined ones, or use an improved design of swash plate. Again, swash plate levelling will be an important part of this.
Lastly, a swash plate tool is essential for any RC Electric Helicopters that have been built in kit form.
The swash plate is probably the most important part of the rotor head, as without it you can have neither cyclic or collective control. But too many people assume that flight problems with their RC Helicopters are down to the blades, flybar, or worn out servos.

It’s true you should check all these things – as well as the centre of gravity. But the swash plate should really come first.

RTF (ready to fly) Electric Helicopters are very accurately set up at the factory. They are test flown, and all the components are thoroughly checked to ensure everything is balanced as it should be.

However, Electric Helicopters are so sensitive it doesn’t take much for things to go amiss. And what if your heli isn’t RTF, but kit built? Or you’ve recently upgraded some of the parts, or had a recent crash?

All of these things can cause RC Helicopters to behave in all sorts of unpredictable ways, even when the rotor and flybar are perfectly balanced.

But first of all, you need to know what a ‘normal’ helicopter feels like because, as you know, they are unpredictable things anyway. The following test will soon tell you if the helicopter you are flying is properly balanced, or if it needs adjustment anywhere.

Check if your helicopter has a clockwise or anti-clockwise rotor (this should be obvious) and that there isn’t any obvious juddering or odd transmitter responses, which would point to other problems such as unbalanced blades or tracking. (We will assume your RC is working accurately).

The first thing to do is remove any training kit you’ve got on the undercarriage. You want this bird to be unstable.

Next, get her hovering just off the ground, just enough throttle to keep her airborne. Yes, she will jump about like a ferret in a sack. Now note the drift. RC Helicopters with clockwise rotors tend to drift to the left, this is a natural effect of the torque, and remedied on the transmitter. Anti-clockwise is obviously a right-hand drift.

Increase the throttle, the head will swing sharply to the left, (for clockwise rotors) with some counteraction by the gyro. Decreasing the throttle will cause the head to swing right.

If this is all you experience, the swash and C of G are fine.

However, if the tail or head drop when you lift off, then the centre of gravity needs adjustment. RC Helicopters that drop to the left or right have a swash plate problem.

If the tail itself is swinging oddly, it’s the rudder and/or gyro that need attention.

Whenever any work is done on the flybar, whether kit building, upgrading or replacing – it is important the paddle adjustment is realigned. RC Helicopters rely on correct placement of the paddles, to ensure accurate cyclic movements.

The flybar paddle tilt should be parallel to that of the swash plate. Although there are paddle gauges for RC Electric Helicopters, they are not really necessary, in fact, they can be too heavy for the paddles of smaller Electric Helicopters. A steady eye and some basic measuring tools are all that’s required.

Place the helicopter on a level surface – a work bench is ideal.

First of all, check that the paddles are parallel to each other. If they are not, you will need to loosen the paddle mounting screws and adjust them.

Align the rotor blades fore-and-aft with the body. Now lower one of the paddles and align the outer edge so it is level with the top of the swash plate. If you have had to tilt it to do this, the swash-to-paddle linkages need adjusting. On Electric Helicopters, this is done by shortening or lengthening them.

Rotate the rotor head 90 degrees. The paddles will now be aligned with the helicopter body. Check the same paddle is in the same position, relative to the swash plate.

If it isn’t, repeat the procedure again. If you still can’t align the paddle properly, it may be the swash plate needs balancing (see article on swash plate levelling)

Hopefully, the paddle and swash plate will be level, so repeat the procedure with the opposite paddle; again, check the alignment at 90 degrees.

Before flying, make sure all linkages are securely tightened.