Radio Control Models & Electronics - Jun '94

by Stan Yeo

INTRODUCTION

This article is for those occasional readers that are interested in taking up radio control model flying and more particularly slope soaring as it is my speciality. Two recent events finally persuaded me to put pen to paper, one was the interest shown by youngsters and their parents in flying model aircraft on a 'Young Engineers' evening at a local secondary school. The second was a chat I had with BARCS (British Association for Radio Control Soaring) officials at last years Sandown show re the age profile of competitors in the BARCS flat field glider events. They were concerned about the possibility of competitors collapsing whilst towing up gliders on no wind days. Both conversations made me think about the accessibility of our hobby to prospective enthusiasts hence, this article.

WHAT IS SLOPE SOARING ?

Slope or hillside soaring is where the aeroplane, model or full-size, is kept airborne by lift generated when the wind is blowing on to the face of a hill or cliff. The air, unable to go through the hill, is deflected upwards and over it. The lift generated is dependant on the size and shape of the hill, the terrain in front of it and of course the strength of the wind. If the wind is too light it does not produce very strong lift but likewise, if the wind is too strong the lift gets 'flattened' making it difficult to fly the lower performance models (see diagrams below).

IS IT EXPENSIVE ?

Slope soaring is the least expensive form of radio control model flying. It does not require expensive engines or radio control equipment. It is possible to get airborne with new equipment for less than £100. For this you can buy a basic trainer model and a 27 Megahertz 2 channel set of radio control equipment with 2 servos. Most modellers would advocate a slightly more sophisticated set of R/C equipment for reasons to be outlined later, but on a recent visit to Wales I met a group of modellers who had been using 'such' equipment for a number of years and were more than happy.

Running costs are also low, typically £10 a year for insurance (an absolute must these days) plus your club subscriptions. These can be as low as £5 a year to £20 plus if the club has to hire a room for club meetings and/or rent has to be paid for the flying site. Some clubs provide third party insurance cover inclusive in their membership fee. Most modellers build one or two models a year. The least sophisticated of these will cost around £50 to build from a kit, a little less if built from a plan. There are more sophisticated models available and most modellers do progress on to them but only after they have learnt to fly. In addition to insurance club subscriptions and replacement models there is of course the cost of driving to and from the flying site but this applies to most leisure activities.

HOW DO I START ?

As with most leisure activities the best way to start is to visit the local shop specialising in your leisure activity in this case the local model aircraft shop. There is a model shop directory in the back of this magazine. Most model shops have a list of clubs operating in the area along with contact names and telephone numbers. Building and flying model aircraft is not easy but it is well within the capabilities of most people. Success is almost assured if help and advice is sought from a competent modeller. You will need help in selecting the right model to build, building the model and most importantly learning to fly it. Whenever a modeller is in the company of non-modellers there is invariably the story about a modeller who spent ages building an all singing and dancing model aeroplane only for it to crash on it's maiden flight. These crashes unfortunately do happen but very rarely and far less frequently than the non- modelling public perceives. It is rare for a novice's aeroplane to be written off on it's maiden flight particularly if that novice has sought help from an experienced modeller. My experience suggests that model flyers do not generally start seriously damaging models until they have gone 'solo' and are flying more aerobatic machines.

Having made contact with the local club find out where they fly and when and where they hold their clubs meetings. If you have a choice of clubs it goes without saying that you join the one that is more interested in your type of flying. All clubs will do their best to help novices but please remember that most people are inherently shy and consequently you may have to ask for help!

CHOOSING THE MODEL

Subject to the advice of the club you have joined my advice is that you build a simple, rugged, watch it bounce, Rudder Elevator model of moderate span (1.5 metres) that is easy to fly. Up to a point the 'boxier' it is the better. Some people will disagree with this advice but it is a result of teaching many people to fly over more years than I care to remember. Basically, novice flyers are invariably novice builders so the model must be easy to build and repair should the need arise. It should also have a relatively low flying speed range, fast enough to cope with the strong winds but 'draggy' enough to be speed limiting when things go wrong and the model is plunging earthwards. It is at these moments that 'thinking time' is at a premium and this is when that extra drag could make the difference between a recovery and a crash. Smaller models are generally more manoeuvrable than their larger counterparts and this is important when the 'ab initio' pilot has got past the stage of 'steering' the model around the sky and on to the stage of learning to fly instinctively. This can only be done by throwing the model around the sky and honing your reactions under pressure.

There are a number of good trainers on the market and three that I have knowledge of are the Soar Ahead Sailplanes 'Ace', Chris Foss's 'Middle Phase' and the Phoenix Model Products 'Ab Initio' and 'Stage Two'. There are others and no doubt the editor will hear from the manufacturers of those not mentioned!

CHOOSING THE RADIO EQUIPMENT

Unfortunately the most economic route is not the recommended route for most modellers i.e. the 27Mhz, 2 channel, twin stick sets mentioned previously. Information from the 'trade' suggests that at least 85% of all model flyers fly with the primary controls on the right-hand stick. The primary controls are Elevator and Ailerons or Rudder if ailerons are not fitted. Modellers are very reluctant to fly other peoples models if the control stick configuration is different from the one they fly. It is like driving a car with the clutch and brake positions reversed! It is recommended therefore that you buy a 4 channel set with the Throttle control on the left-hand stick. This obviously increases the initial cost but it cannot be helped. The cost is further increased as it is recommended that you buy a set with rechargeable batteries. The extra cost is soon recouped however after just a few flying sessions as dry batteries are not that much cheaper than rechargeable batteries. They also give added confidence knowing that the model is less likely to crash through battery failure providing of course that the batteries were charged in the first instance. Most 4 channel sets are available with any number of servos but it is recommended that at least three servos are bought so that one is available when a three function aileron model is built. Most model glider pilots fly on even number transmitter frequencies. Some clubs insist that members adopt this protocol so it may be advisable to check this out before you buy the radio control equipment otherwise you may find that you have to buy an extra set of crystals on an even numbered frequency. Modern radio control equipment is very reliable and is therefore a matter of personal preference so other than choosing a set with adequate servicing and spares backup no recommendation is made.

Well, I hope you found this article of value and you are tempted to have a go. Even if you are still undecided make contact with your local model club and have a chat with the members at the flying site. You never know they may even persuade you to fly one of their models!

Airflow over a slope

Transmitter configurations

Photographs of a selection of trainer type models and radio installation