Gibbs Guides.com

More high quality information absolutely free with every
Gibbs Guides newsletter. Sign up now!

Choosing equipment

By Andrew Gibbs

3 or 4 channels?
It’s fair to say that opinion is divided about whether a 3-channel (rudder, elevator and throttle) or a 4 channel (3 channel controls plus ailerons) model makes the best vehicle for training. Certainly a 3 channel model is simpler and this simplicity has a lot going for it especially in the early stages of learning. Proponents of 4 channel models argue that it’s best to start off with ailerons.

I feel that particularly for mature modelers, a 3 channel model is more than enough of a challenge to be going on with. In contrast, introducing ailerons straight away is perhaps a more suitable approach for young pilots. That said, my own experience was that I started RC flying as a teenager with a 3 channel model, and personally I think I’d have found 4 channels to start with a bit much. The choice is yours!

Model choice - ARTF, or build from a kit or even from a plan?
Another choice to be made is choosing between an ARF/ARTF (almost ready to fly) model, and a traditional model kit which will require building. Also possible, but most challenging is to build a model from plans. Kit and plan built models are an excellent solution if you like building and aren’t in too much of a hurry to start flying. It must also be noted that the satisfaction gained from building a model yourself cannot be matched by merely assembling an ARTF model.

The big advantage of ARTF models is that they can be assembled relatively quickly, so they allow a rapid start to flying. Also, the emotional investment in such a model is much less, so should the worst happen and your model becomes badly damaged, at least you won’t have invested a lot of time and effort in building it. The choice is yours, and either approach can give you a great start to electric power flying.

Another possible approach is to buy both types – perhaps start with an ARTF to allow you to start flying with the minimum of delay, and then find a kit to build in the meantime.

One final possibility is to buy a second hand model. This has the potential to offer a significant time and cost saving, especially if it’s offered with all the equipment necessary to go flying. However, purchasing a second hand model is fraught with potential problems. To avoid these it would be wise to recruit expert help to guide you.

Well, that’s covered model selection fairly thoroughly. Let’s now move on and discuss electric power systems:

Brushless motors and ESCs such as this example from www.4-max.co.uk offer inexpensive powerful and reliable solution to electric model power needs.

Motors and ESCs
These days, brushless motors and suitable electronic speed controllers (ESCs) are relatively inexpensive, and this combination would be my first choice for a beginner to electric power. Compared to a brushed system, brushless power systems are more efficient, lighter, require no maintenance and frequently don’t cost any more.

However, brushed motors may still be used successfully for certain models such as vintage types and powered gliders, so if you already own a brushed system there may be no need to replace it just yet.

Batteries
These days, the battery choice for model aircraft is usually considered to boil down to a choice between two types - Lithium Polymer (LiPo) or Nickel Metal Hydride (NiMH) types. LiPo batteries are the usual choice, mostly due to their light weight.

LiPo batteries offer excellent performance. They need to be used with care to avoid problems.

However, for several reasons, most especially to do with safety, LiPo batteries must be handled with more care than other types. From this perspective, they are perhaps less suitable for beginners than any other battery type. However, many LiPo batteries are in use by beginners and problems are relatively uncommon, especially if the time is taken to learn how to use them properly. LiPo batteries require the use of a balancer. The Gibbs Guide to LiPo batteries is highly recommended for anyone using LiPo batteries (well, I would say that wouldn’t I?!).

As a beginner, if you want to go the LiPo route then its probably best to avoid the larger size of trainer both because the associated smaller battery will withstand crashes much more readily and because a smaller LiPo is inherently less risky than a large one. If you have experienced help to assist you in leaning to fly this issue is less important but it’s still worth bearing in mind.

If you aren’t comfortable with the idea of LiPo batteries, then NiMH types are a perfectly practical alternative. They weigh a bit more, but they are much more tolerant of mistakes and won’t catch fire. Their weight can actually be an advantage in some short nosed models (such as certain vintage types) where nose weight would otherwise be needed anyway. Also, they don’t require the expense and complication of a balancer and they will withstand the physical impact of crashes and the mistakes of rough handling much better.

A third choice is also available. These are known as A123 cells, and are a form of lithium cell. These are nearly as light as LiPo cells, extremely robust and don’t carry a significant fire risk. However, they are bulky, not widely available and are only available in one size.

Safety wise, probably the most important issue to take care of with any battery type is to avoid short circuits by (a) the selection of a suitable connector system and (b) taking care in use.

Battery and motor combination
Brushless power systems are usually combined with LiPo batteries, although this is not essential. Although less usual, it’s perfectly possible to use a brushless motor with a NiMH battery, or even a brushed motor with a LiPo battery. However, in every case the ESC used must be suitable for the battery chemistry in use.

A folding prop is another way to reduce the likelihood of prop damage on landing

Propellers
One factor of particular importance with electric power models is the propeller - it’s vitally important that a suitable example is fitted to your model, and unfortunately experience with i.c. engines is often of only limited help here. The prop must be a good match to the model and to the rest of the power system, with an appropriate diameter and pitch. If the propeller is too small in either dimension, the model won’t have enough power to sustain flight, yet if it’s too large the model may well be overpowered, plus the motor and ESC may quickly become damaged.

When training, the prop may be expected to make frequent contact with the ground, for example in less than perfect landings. A rigid, easily broken prop is therefore a bad idea for beginners. A flexible alternative is probably a better choice. The possible reduced efficiency of a flexible prop is of no real significance with training models and may be ignored. Folding props are another solution to the issue. Do make sure that your props are balanced. Out of balance props can produce a surprising amount of vibration, which will waste power and perhaps cause damage to your model and its equipment.

You’ll need a charger for replenishing your batteries.

Choosing and using a fast charger
When starting out with electric models, it may be tempting to buy a charger that suits your immediate needs only. However, it may be worth spending a little more on a charger that will be able to meet future needs as well. There’s a wide choice of compact microprocessor controlled chargers that can deal with a variety of battery types at very reasonable prices. Provided that these come with easy to understand instructions they can make an excellent choice. I recommend checking the issue of instructions carefully; it’s no good having a capable charger if its instructions make it hard to use – this problem is all too common.

RC gear
If you’re unsure of your commitment to RC, or you don’t relish the thought of learning to programme a computerized transmitter, then get a basic, non-computerised 4 or 6 channel set. This will be quite sufficient for a wide variety of models. Make sure the servos are suitable for the model you have in mind; for many trainers ‘standard’ servos will be adequate. Smaller models will however need ‘mini’ servos.