Thursday, December 16, 2010

RC Planes hobby

I am in the midst of developing a new hobby on remote controlled (RC) airplanes. This RC hobby is something that I wanted to do long time ago. The lack of knowledge and also the cost of embarking on this was rather high which therefore had delayed me for years. I chanced upon Encik Jaafar who is a veteran RC flyer and he had taught me patiently the very basics of air modeling and I am intrigued by the technicalities and also the skill that required to be developed in order to learn up this hobby.

There are some of the basic terms that I picked up over the course of the learning process. The key control components of the plane include its rudder, ailerons and elevator. Each of these control surfaces is linked by a rod which is pulled or pushed by a servo. The servo is a device that rotates, and the rotating motion is translated into a linear motion that pushes and pulls the rod that ties to the control surfaces into their various desired positions for flight control. Normally if they are 3 control surfaces, then 3 separate servos are required to do the job. In additional to that, there is another servo requires to control the throttle of the engine. There is a electronic receiver gadget, as the name implies, it receives the signals from a transmitter hand held by the flyer, with the control sticks on it that navigate the direction and movement of the plane. Each of these wireless signals generated by the control stick movement is then fed into the receiver installed inside the plane high up in the sky. The receiver then relays those signals to the individual servos that moves the respective control surfaces into positions. In this case, the receiver is said to be making use of 4 channels; one channel to control the rudder and front wheel at the same time (Left and Right), one that moves the ailerons on the wings (Tilting the wings Left and Right), one on the throttle (Speed control) and the last one is the elevator at the tail (Up and Down). My Futaba 6EX transmitter could control 6 channels, there are 2 more channels left after using 4, which at later part could be utilized to control more features of advanced planes or helicopters.

I had to purchase a Thunder Tiger 2 strokes engine of 0.46 cubic inch on nitro fuel to power the plane. The engine needed to be run-in so that it could function smoothly over a range of speed and RPM. This is in some way similar to buying a new car that needs a run-in period for its new moving parts of the engine. There are a lot of aerodynamic theories involved in flying RC planes. It is hard for non-technical people to understand how a propeller that spins clockwise viewed from the pilot seat, could generate a torque that tends to push the aircraft to the left. Instead of mounting the engine at exactly 90 degrees to the wings, one therefore needs to mount it at a slightly inclined right thrust angle of about 2 degrees so as to compensate this sideway movement. This will ensure the plane to fly straight instead of towards the left all the time! Similary there is a down thrust angle such that whenever one throttles up, the plane will fly upwards, otherwise it will start to descend. The transmitter also provides some fine trimming controls to correct this as well! All these seem complicated to be described in words but it is a lot of fun when you really hand-on and get a grasp on what I had mentioned here. It is better to fly one yourself in order to get a better feel on how one could actually navigate the flight! Yes it is indeed great excitement to see those toys up in the sky flying like birds.

I had bought one RCM 40 trainer plane which has high wing (mounted on top side of the plane body) of 63" wing span. This is a slow speed plane that could float and glide well in the air for beginner. And I also purchased another small electric powered Cessna 182 EPO plane just to train on the dexterity of my fingers over the control sticks of the transmitter. One has to finger on multiple controls simultaneously, for example, when a plane turns its direction with the use of the rudder or ailerons, it tends to descend, one has to pull up the elevator a little bit so that the plane will climb back to its horizontal flying position.

Setting the sensitivity of the throws of the controlling stick on the transmitter using dual rate and exponential is another fascinating topic. Simply put, during certain delicate control situation such as landing, one needs to make the moving of the stick less sensitive corresponding to the servo movement especially the elevator, so that the plane could do a soft landing in a gradual gliding down and graceful manner.

It is not a easy hobby as I first thought, and I damaged one of the wings of the trainer nitro-plane and also crushed the front portion of the electric Cessna 182. But I hope to master the hobby within the next 2-3 months when the monsoon season is over and the weather is getting better for more viable flying practice sessions.

I have a phobia for height since I was kid but I yearn to be high up in the sky. Look like this dream of flying high could only be fulfilled via this hobby. One day I hope to fly the low wing aerobatic plane and the more complicated helicopter. It would be my next project to mount a camera on one of the planes to capture some scenic aerial views from above the sky.