The GMFC Guide to helicopters.

By Dave Perry

Part 2 – Helicopter – next steps

Ok, so you have worked through the basic type of helis, but a few terms keep cropping up.

Flybarred vs Flybarless

Flybarred helicopters usually have a flybar orientated at a 90 degree angle to main rotor blades. On the smaller micro helis these maybe at 45 degrees to help with stability. They will often have paddles and weights at the end. The flybar is allowed to pivot up and down so it can stay in a level horizontal plane independent of what the main rotor angles are.

 

In this way if a gust of wind was to hit the heli and tilt it sideways, the flybar wants to stay horizontal. This is transmitted to the main rotor blades which helps stabilise the heli by changing the pitch angles of the main blades to help counteract the gust long enough for the pilot to then put stick movements in to fully stabilise. For the beginner, because the swashplate movements go to the flybar and not directly to main blades, the pilot’s cyclic movements at the stick are somewhat dampened and therefore not quite so sensitive to the helicopter. The degree of this dampening can be adjusted by moving the weights along the flybar, the further out they are from the head the more the flybar will absorb movements making it less sensitive for the beginner.

A flybarless heli, by its name, removes the flybar and uses electronic stabilisation to ‘virtually’ replace it. There are different types of flybarless heli, firstly in respect of the different types of mechanics around the main rotor headblock, the most recent being the DFC (direct flight control) which totally removes the swash driver.

 

Second, around the computerisation, with different flybarless electronic systems available. A flybarred system will generally have one gyro for the tail rotor (to detect yaw), the virtual electronic system of the flybarless heli adds two more gyro sensors that detect pitch and roll attitude and then move the servos to tilt the swash to make pretty precise and quick cyclic changes (similar to those that the flybar would have made to the main rotor blades). These three gyros are now commonly included in one unit, which in more modern flybarless control systems also now includes the radio receiver for the heli as well.

 

 

As a result of the electronic stabilisation the helicopter is more likely to feel ‘locked in’ during flight when compared to a flybarred system. For the beginner, at least in the hover, if both types of heli have been set up properly you are unlikely to notice much difference (although there is a slightly different take-off manoeuvre for each). Mechanically the flybarless system has less mechanics, so is less fiddly around the head, less to replace in a crash, and will be slightly lighter and more aerodynamic giving slightly longer flight times. Clearly being electronic, some versions are now coming with more advanced pilot aids, including rescue modes which at a flick of a switch on the transmitter can level out the heli or put it back into an upright orientation. On some models of flybarless (FBL) systems such as the MSH Brain, you can also computer programme the unit to set maximum amounts of roll or pitch angle so that the heli will never pitch or roll past those limits.

Of course the FBL system does have a number of disadvantages over the flybarred system as well, one of the biggest being cost (for the proper sized heli – not the micro heli where it is almost standard now). Although as with all technology the price continues to fall and the gap gets smaller and smaller (certainly for some of the basic FBL systems atleast). It is also becoming more difficult when purchasing new now to find flybarred systems, but if looking to pick up a cheap second hand heli, there are still plenty around and nothing the beginner should be overly worried about.

Another potential disadvantage for the beginner will be the added complexity of setting up. Again, this is where you are likely to require some help if new to the hobby. The FBL will require more set up than a single tail gyro on a flybarred heli, and whilst not difficult once you have done it before, the programming (and manual) can be a little daunting the first time round. Further some systems will require atleast a hover, and potentially some basic flights to set the system and gains properly.

If as a beginner you do decide to go down the FBL routes, then two final thoughts. As set out above a FBL can be more responsive than a flybarred version (less dampening) and with higher rotor head speeds, which is not necessarily what you want when starting out. So when buying your FBL system make sure you purchase one which is capable of being tamed down to be less sensitive. It is also worth checking that if you intend on using training gear on your heli, that the FBL system you choose is capable of supporting it. Not all FBL systems are beginner friendly, and many can add an additional layer of complexity to what is already a bewildering hobby for the newcomer. Learning to fly collective pitch helicopters is difficult and there are no real short cuts to stick time, flying FBL is different to flying a flybarred heli, but don’t believe it will be any easier to get the basics right over a properly set up flybarred one!

Helicopter power

In the micro heli market you have no choice, these are all electrical and mainly powered by one or two cell lipo batteries. Most helis will come with normally one battery and a charger to start with. It is worthwhile ordering some more batteries at this point so you can have 5 or 6 flights before having to head back to the charger. You can go with the battery from the helicopter manufacturer, or purchase compatible batteries from other makers, normally at a cheaper price in this model bracket – just make sure they have the right connectors on them!

When you get into the larger size helicopters you start to get a choice between going electric or the nitro fuel route. Only a few years ago you would probably have gone nitro, but the electric market is moving fast and the power and performance is now excellent, so the sands are moving.

 

For the starter nitro may throw a number of additional factors into the flying melting pot. It is messier, having to deal with nitro powered engines, pumping fuel into the heli tank, carrying nitro fuel around with you, and then starters and glow drivers to fire the heli into life. Many would now say that electric helicopters are more convenient and potentially more reliable. Once your batteries are charged you simply strap them on, do your safety checks, connect them up, and off you go. The electric heli in my opinion is quieter, and therefore better as you get to hear the proper noise of the rotor blades – far more realistic. Of course you don’t get the smoke trail from the engine on an electric, which can be helpful for the beginner in showing you what the heli is doing in the air, and a visible demonstration of things like ground effect.

Electric flight is being aided by competition in the battery market, and the falling price of LIPO batteries. Nevertheless these can start to become expensive when you are looking at 6 cell batteries. In most cases they won’t last as long in flight as a tank of nitro in a heli as well, whilst there will always be exceptions that break this rule, you can probably expect upto 10 minutes of a good lipo with steady flying, compared to 15-20 minutes from nitro. Plus in the larger 600 and 700 helicopters you are probably going to need two large 6S batteries in series for each flight. Multiply this by 4 or 5 pairs so you are not consistently sitting around a charger between flights and you can be up to an initial cost equivalent to that of the helicopter itself.

However, if you get a good lipo charger, and you look after your lipos properly (storing in right conditions at storage charge, not overly discharging on flights) then you could get at least 300 flights of each pair, starting to make the cost per flight more attractive when compared to nitro in the long run. A pair of 6S batteries costing £140 equates to £0.47pence per flight. With 5 litres of nitro costing say £20, which could equate to about £2 per flight (or £1.25-£1.50 for a flight of comparable time).

Like with nitro fuel, you have to look after and be careful whilst charging LIPO batteries, there have been nasty accidents when lipos have caught fire, so you need to read up and use and charge these safely. In this respect you will need to buy yourself a decent charger, and possibly a separate power supply. Going the nitro route you will equally need to buy some field equipment, including a hand/electric pump to move the fuel into the heli, a glow plug and starter. Whichever route you go these are likely to cost you in excess of another £100.

Other kit?

So you’ve purchased your starter or battery charger, nitro or batteries, what else are you likely to need.

Transmitter

Well if you think you are going to be getting into this hobby for proper, then it is worthwhile investing in a proper transmitter. Again these have developed massively over recent years, and you should be looking for a 2.4GHz transmitter. There are many brands available of different size and ability, so plenty of research in this area will pay you dividends, including actually holding your preferred choice to make sure it feels comfortable and you can easily reach the switches etc. Again most people will fly Mode 2 these days, with throttle and tail rotor on your left thumb, and cyclics on your right thumb (up, down, left and right).

At entry level you will wanting to look for a minimum of 6 channel capability, but ideally 8 if you can stretch to it. They need to be computerised so that you can programme them for heli use, including things like throttle and pitch curve, throttle hold, idle up (f mode/stunt mode) and setting things called exponential rates and dual rates. The great news is that this is now standard on all the main transmitters such as the spectrum DX6, DX8 etc, or equivalent Futaba, JR etc models.

One of the main advantages of purchasing your own transmitter is that they can be programmed to fly multiple helicopters, planes, quad etc through a model select function. Each model is set up in the transmitter’s memory, and once bound to that model, you choose the model you want to fly from the menu and off you go. No more carrying multiple transmitters around with you!

If you are serious about the hobby, then you should look to go for one of the main branded products to ensure quality and improve compatibility. As mentioned earlier, you will also need to purchase a receiver to go in your helicopter, and it makes life easier for the beginner if the two are branded the same – spectrum to spectrum or futaba to futaba. Spectrum seems to be a popular choice in the helicopter market simply because many of the micro collective pitch helicopters come with spectrum 2.4GHz receivers built into them.

Finally sticking with one of main branded transmitters will help when it comes to programming them for your helicopter. The main web forums will be full of the settings fliers have used in their set up, both for taming down as a beginner, and for the expert flier. The manuals for many of the micro CP helis, e.g. the Blade 130X, will also normally include all the recommended settings for the Spektrum DX6, 7, and 8 transmitters. Using an SD card you can often download the settings for many heli’s from the web, and copy them into your transmitter if it has an SD slot, but again understand and check what you are downloading! A new spectrum DX8 transmitter will set you back a little over £200, but can often be had as part of packages when purchasing a larger heli as well at good discounted prices. They can also be had in a package including a spectrum 8 channel receiver, which is also great if you are looking for a receiver to go in your heli as well.

 

Field/flight box and tool kit

Whether you are looking to build your first heli from a kit (which is great experience, not only in knowing it has been built properly, but also understanding how it goes together for when you need to repair it), or having to maintain and repair it later, there are some basic tools you will need.

Ideally you are going to want a set of good quality hardened end hex driver, a basic good quality screw driver set and some needle nose pliers. In addition some specific tools you will require will include some ball link pliers, some instant CA glue, and blue threadlock. Over time, unless you can borrow some, you will also need a pitch gauge for setting up the pitch angle of the main rotor blades, and a digital volt meter. Finally a good quality soldering iron, solder, silicon wire and heat shrink. If you are going the electric route you will also need to think about what battery connectors you are going to use to connect the larger batteries to your heli (e.g. deans, EC5) and get a selection of these, together with a battery checker to check the state of your batteries at the field before flying.

Miscellaneous

Other things you may want to consider will be a carry case for transporting your pride and joy around and making sure it doesn’t get damaged in the car.

As a beginner you may also want to consider buying some training gear if starting off on the medium to large helis.

 

Flight simulator

For the beginner a good investment can also include purchasing a good quality flight simulator (something like Phoenix or Real Flight). This is a software programme that you load onto your PC at home which seeks to replicate the flight of RC helicopters and planes. Some will come with their own ‘transmitter’, or you can get a USB type adaptor that enables you to use and plug in your own transmitter. If used properly these can be great for helping ‘program’ the mind in respect of helicopter orientations, hovering, and later on aerobatics. However, you can also pick up bad habits on them which you may then have to unlearn when flying the real thing.

Another word of caution is that you have to see them as a tool. Don’t think that because you can fly a heli on a sim, you can jump straight onto a real collective pitch heli and do the same thing – you can’t! There is also the psychological fear factor of flying the real thing, with a sim if you crash it or it flies off you just hit the reset button, not the same with the real ones. It is not as easy with the real thing and nerves and adrenalin will kick in! let alone other environmental factors such as wind, other people flying etc. The chances are on a sim you will be flying around the skies, looping, inverted, rolls before you can even do a competent figure of 8 with the real thing!

So, bottom line is if you can afford a sim, and put some thumb time in on it, it is likely to pay for itself and cut your learning curve/time on the real thing. It is probably also going to save you some time and money on repairing your heli, but you need to understand their limitation and use them correctly.

Warning

Be careful when buying second hand, especially online. There is a lot of kit out there of varying qualities. A number of the major brands have also be cloned, so make sure you know what you getting, and how well it has been built. Ideally see it flying and have a chance to inspect it first. Once bought, the safest thing to do is strip it down and rebuild, for example making sure there is thread lock on all the screws. Some is being resold because people bought incorrectly in the first place, don’t follow in their footsteps!

Part 3 – Helicopters – which route?

The smaller micro helis will generally be ready to fly out of the box, but in practice this hobby generally involves three steps at some point in your development.

Building. The chances are at some point you are going to have to build a heli, either from scratch with one of the bigger ones, or during the repair stage after a crash. This is an important part of the hobby, it helps you understand your heli and after time note when things aren’t quite right more easily. Apart from the smallest of models (150, 250 size which can be fiddly), this isn’t too difficult – especially if you buy a ’combo’ kit, the manuals are generally good and there are always forums when you run in to trouble. The only really new skill you may need to learn is soldering if you go the electric route. If not for your battery terminals, then normally for connecting your motor to speed controller.

Set-Up. Once built you will need to set up the heli. Make sure all your wiring is done properly, receiver is plugged in correctly, and wired to giro/FBL unit etc. You will then need to use a pitch gauge to set the pitch of the main rotors, and programme your gyro/fbl unit and gains, potentially also your electronic speed controller, engine setup etc. Finally you will need to programme your transmitter and bind it to the helicopter including setting the appropriate fail safes and testing them. If you are new to the hobby this is the stage at which you are likely to need some help, either from your club, other hobbyists or instructor. RC helicopter can be lethal, and it is therefore critical you are confident it has been built properly and set up before you fly. The first few hovers/flights will normally be used to do the final set up – ‘gains’, pitch etc.

Flying. You need to learn to fly and develop your skills safely. Again call on the support of your club and others, sim, and/or instructor.

So which route should you choose as a beginner? Well this is a topic that can run and run and run, and often does on the heli forums. There is no real or right answer, and different things work for different people. Some say just jump in to a full size helicopter and go for it, others say work up through the micros and get some experience and then transition to the bigger stuff. Others I know just love the fun of the micro helis, and have no intention of getting onto the bigger helis, filling this whole with their RC planes. However here is just one potential route to throw into the melting pot for your consideration.

A basic route summarised!

Do some research. Read the internet forums, join GMFC (and BMFA) and come talk to the members, see the size of models flying. Don’t take the first advice you are given. Talk to the current beginners about their experiences – the models have moved on and what was right 5 years ago may not be now! This will save you money in the long run from not buying the wrong kit.

Have a flight with a volunteer instructor or professional instructor on a buddy box and see what you think! If you like have a few more lessons to get the basics and take their advice on model route. They are likely to be the ones helping you set it up!

If you can afford it as well as a heli, buy a flight simulator to practice on your PC.

Buy a good quality branded transmitter with at least 6 channels, spectrum if you plan going the Blade micro route at some point.

Consider your first helicopter purchase – are you going to go the micro route, or the full size, or possibly both if you can afford it.

If you think you may need something very stable to start with purchase a coaxial micro, otherwise jump this stage and go for a good quality fixed pitch hobby grade micro like the MSRx. You will need some space to start with, and remember the throttle hold switch!

Practice and get confident with hover, orientations, and nose in. When ready consider moving to a collective pitch heli. Again have plenty of space. Consider if you are going micro again or moving to a larger heli. If going larger don’t go smaller than a 450 size and consider a 500 size (build it yourself and use blue threadlock!). Remember the larger the more stable, but the more expensive and the more damage it will do when you crash.

Choose a brand where there are spares available and you can afford the spares!

Get help with set up and your first flights, tame down the heli as much as possible. Use some training gear for the bigger helis and if possible learn on a hard surface you can ‘skate’ over until you have mastered the hover (not in a public or enclosed area). For a micro heli fly over long grass if possible but you will need a flat take off pad. These will save on repair bills. Have plenty of space around you. Comply with the BMFA guidelines and remember at all costs that these are not toys and need to be respected.

Get as much stick time in as you can, either the real thing or on the sim, you need to programme your mind! Use throttle hold when not spooled up, and get practice of using throttle hold when you are about to crash and not pulling down the throttle stick.

Remember it is a great hobby with some great rewards, but it requires sticking power, and time. Part of the fun is being part of a club, so join GMFC, and take part in the social fun down the flying field as well. Learning from an instructor, either volunteer or professional, is the best way because they can also help you with your helicopter setup and ensure you get the basics of safe flight right from day one!

Remember to have fun!

 

(written 2014)

 

BACK

Gloucester Model Flying Club