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The rudder and elevator surfaces seen here have been carefully checked to make sure they line up exactly with the corresponding fixed surfaces.
To keep control movements reasonable without introducing excessive ‘slop’, make sure you use the outermost hole on the control surface horns, and one of the inner holes (as required) on the servo arm. For the same reason, take care not to make the holes in the servo arms and control horns any bigger than absolutely necessary.
Only after limiting overall movement in this way should you use the transmitter's travel volume function (ATV for Futaba) to reduce it down further if required.
Set up issue: Appropriate power
Training models need to be appropriately powered – too little power will make the model hard to keep airborne, while too much will make learning to fly much more difficult for a beginner than it needs to be. Training models are often fitted with much more power than they actually need. The usual answer to this criticism is that the engine can always be throttled back, but timely and appropriate throttle management is a skill that only experience can provide, which is something the beginner is very short of. Excess power in a model produces a number of side effects that the beginner will simply not be well equipped to deal with and which will make control much harder compared to an ideal model. These include the following, any of which could allow a model to 'get ahead' of the pilot flying it:
1. The model will be faster.
2. The rate of climb will be higher (perhaps much higher).
3. The control responses will be sharper due to higher airspeed and because of the high speed prop wash over the tail.
4. The asymmetric forces resulting from prop rotation will be higher. Engine side thrust may not be enough and the model may difficult to control during take off.
5. The model may have a strong tendency to pitch up sharply under full power, possibly leading to a stall.
In short, excess power can transform a pleasant handling training model into a high performance machine requiring a high level of expertise and experience to handle successfully. Full sized basic training machines are always modestly powered and in my opinion RC training models should be as well.
Pleasingly, the issue of power is an area where electric power has an advantage – simply by fitting a smaller prop, the maximum output power of an electric motor can be reduced at will. So, choosing a larger than necessary motor for an electric training model can indeed be a sensible decision, provided that the model still remains sensibly powered by an appropriate choice of prop. Depending on the model type and power system efficiency, as little as 40 - 50 Watts per pound of model weight may be sufficient, and less may actually be better for the trainee pilot.
I’ll conclude this section with a specific recommendation - a training model is properly powered for a beginner when it will climb at a moderate rate at full power with the model in an appropriate state of trim, i.e. at not too fast an airspeed – just like a full size training aircraft.
up issue: Undercarriage
(gear) and wheels
Whether trainer or otherwise, the undercarriage must be adjusted if necessary to ensure good ground handling.
It’s important that the ground handling of your model is good, otherwise every take off will be fraught with difficulty. All the wheels on your model must turn freely otherwise it may tend to veer towards the sticky wheel. You can expect to have to add a little right rudder on take off under high power conditions due to prop effects. However if the model won’t roll straight on the ground even at low power then the undercarriage will probably need adjusting. Don’t adjust the rudder control for this purpose, otherwise it will be permanently deflected in flight and cause other problems.
This model has been fitted with large
Trainers sometimes benefit from having oversized wheels fitted. These will allow the model to handle bumpy ground more easily. Some full size light aircraft have enormous ‘tundra tyres’ fitted for this very reason. The extra aerodynamic drag of large wheels can be considerable and this will also help to keep the speed of the model down in flight.
up issue: Installing the
RC gear correctly
This subject is far too large to cover in detail in this short article, but a few of the most important areas can be covered.
Ideally the receiver will be wrapped in foam to protect it from vibration. This precaution particularly applies to non - 2.4 GHz equipment. In any case, make sure the receiver is not too close to the ESC and any associated power system wiring. Any UBEC unit (separate BEC) if fitted should also be distant from the receiver and RC system wiring.
The receiver aerial must be undamaged and stretched out to its full length, otherwise range may be compromised. If your receiver has a long aerial (i.e. non - 2.4 GHz systems), try to incorporate a vertical element, for example routing it to the top of the fin as this will help improve reception. Never run any aerial along or near to a metal or carbon fibre component of significant size.
Wiring must be arranged so that plugs and sockets cannot come apart in flight. Include any extension leads in your checks and remember that vibration and G forces will be present.
Keep RC wiring physically separate from the wiring or the power system – at least 50mm (2 inches) is ideal. This minimizes the chance of the power system causing interference to the RC system.
This servo has been glued in position using a dab of hot glue.
Where possible, servos should be installed with their rubber grommets and screws. Some models call for servos to be installed directly into moulded foam cavities, in which case this recommendation can be ignored.
Set up issue: Installing the power system correctly
As with the subject of RC installation, this subject is far too large to cover in detail in this short article, but a few of the most important areas can be covered.
The motor should be securely mounted. It must receive a plentiful supply of cooling air. Ensure the prop driver is a firm, secure fit on the motor shaft and that the prop nut is secure. The prop itself must be balanced.
The ESC should also be assured a plentiful supply of cooling air. Don’t wrap it in foam as it needs airflow on all sides. The ESC will emit radio interference, so Keep it spaced well away from the receiver if at all possible. ESCs can be successfully mounted on the outside of a fuselage – an ugly but practical solution.
This LiPo has been securely retained using a strap.
Make sure the battery is securely retained so it cannot move in flight. You'll need to arrange for a supply of cooling air to reach the battery. LiPo batteries are physically a little delicate, so another idea worth considering is to position a chunk of stiff foam such as polystyrene in front of the battery to absorb some of the impact of a heavy landing.
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