Kent County Aero Modelers Hints & TipsKent County Aero Modelers Hints & Tips
 

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The subject of actual construction of a trainer is far too involved and lengthy to be covered in depth here. The trainer that the beginner chooses should have a good set of plans and step by step instructions that guide the complete assembly of the trainer including the installation of the radio system. There are many books and articles on this subject that are excellent sources of information. A beginner who has no experience in building balsa models should seek help from an experienced builder to avoid the mistakes that can have disastrous effects.

A beginner should consider using a strong, slow curing adhesive to allow time to correct mistakes during construction. One of the best is an aliphatic resin called Titebond. This cures slowly but yields an exceptionally strong joint and it sands easily after curing. All joints that are subjected to high stresses such as the firewall and center wing joint should be joined with a slow cure epoxy.

The main thing that a beginner must be careful with is the alignment of the wings. Wing alignment is critical in the flight performance and stability of the trainer. The kit's building manual should give detailed instructions as to how this is accomplished and special care should be taken to follow these instructions.

The new radio systems are proportional control meaning that the control surfaces move in proportion to the amount of movement of the stick. If the stick is moved half of its total travel in one direction, the corresponding control surface will move half of its total travel in the corresponding direction. A beginner must first know the effect that a stick movement has on the model. During normal flight, the throttle is set so that a constant speed is maintained. This means that thrust is equal to drag and lift is equal to weight. From this stable condition, the effects that the stick movements have on the trainer are described.

When the right stick is pulled back, the elevator moves up. This causes the nose to pitch upward increasing the angle of attack of the wing and increasing drag. If power is not applied, the airplane will slow down and eventually stall. This means that the air passing over the wing becomes turbulent and lift decreases until weight exceeds lift and the airplane will begin to drop.

When the right stick is pushed forward, the elevator moves down. This causes the nose to pitch downward reducing the angle of attack of the wing and reducing drag. As the airplane descends its speed increases until drag and thrust are again in balance.

When the right stick is moved right, the left aileron moves down and the right aileron moves up. This causes the airplane to roll to the right meaning that the left wing moves up and the right wing moves down. It will continue to roll as long as the stick is held in the same position. When the roll takes place, lift is no longer oriented vertically so the effective lift decreases. As the angle of the roll increases, effective lift continues to decrease and the airplane will begin to drop.

When the right stick is moved left, the left aileron moves up and the right aileron moves down. This causes the airplane to roll to the left meaning that the right wing moves up and the left wing moves down. It will continue to roll as long as the stick is held in the same position. When the roll takes place, lift is no longer oriented vertically so the effective lift decreases. As the angle of the roll increases, effective lift continues to decrease and the airplane will begin to drop.

When the left stick is moved right, the rudder moves to the right. This causes the airplane to swing or yaw to the right. This causes the left wing to move slightly faster through the air causing an increase in lift. The combination of the yaw and the lift increase on the left wing results in a gentle turn to the right as long as the stick is held in position.

When the left stick is moved left, the rudder moves to the left. This causes the airplane to swing or yaw to the left. This causes the right wing to move slightly faster through the air causing an increase in lift. The combination of the yaw and the lift increase on the right wing results in a gentle turn to the left as long as the stick is held in position.

When the left stick is moved forward, the throttle is opened resulting in an increase in speed of the airplane. This causes an increase in lift and results in a tendency for the aircraft to climb. When the left stick is moved back, the throttle is closed resulting in a decrease in speed. This causes a decrease in lift and results in a tendency for the aircraft to descend.

It is obvious from the descriptions of the effects of stick movement, that any movement can adversely affect the flight of a model. These effects can be overcome by using a combination of control surfaces to achieve the desired results. For instance, the right stick can be moved back when it is moved left. The result of this action would be that the nose of the airplane would be raised to overcome the loss of lift resulting in a banked turn without a loss of altitude.

In order to understand how to properly use the controls, a change in thinking may be required of a beginner who has some basic knowledge of control surfaces. A beginner must remember the forces acting on a model in flight and how they affect the model.

The equipment required to get a trainer off the ground can be very inexpensive. There are a few basic items that will suffice to get a beginner into the air and learning to fly but there are other items that can be added to make the job a lot easier.

MINIMUM EQUIPMENT
NAMEDESCRIPTION
Glow Plug DriverClip on battery for supplying power to glow plug
Chicken StickStick used for flipping the prop to start the engine
FuelFuel mixture recommended by engine manufacturer
Fuel BulbRubber bulb used to transfer fuel to model tank
4 - Way Wrench Combinationwrench with sizes to fit glow plug, prop nut, etc.
Tool BoxAny box suitable for carrying the other equipment

These items should cost about $50. This can vary depending on the brand of the items and the place from which the items are purchased. An assortment of screwdrivers, pliers, and allen wrenches may also be needed to perform field maintenance.

OPTIMUM EQUIPMENT
NAMEDESCRIPTION
Glow Plug DriverClip on battery for supplying power to glow plug
Starter Batterypowered motor for starting model engine
FuelFuel mixture recommended by engine manufacturer
Fuel BulbRubber bulb used to transfer fuel to model tank
4 - Way Wrench Combinationwrench with sizes to fit glow plug, prop nut, etc.
Field BatterySmall 12 volt wet or gel cell battery
Field ChargerSpecial charger to charge transmitter & receiver batteries
Tool BoxAny box suitable for carrying the other equipment

These items will cost in excess of $150. The cost will vary depending on the brand of the items and the place from which the items are purchased. Field box kits are available for a wide range of prices but can be built from readily available materials. Plans are available for a simple field box that will fill the needs of a beginner or for a basic necessities field box for a beginner who wants something a little more sophisticated. An assortment of screwdrivers, pliers, nut drivers, and allen wrenches may also be needed to perform field maintenance.




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