Venture over the stopbank at the Willows flying site and you will come across a almost perfect mown grass circle of approximately 40m diameter, and that is where the CMAC control line activity takes place.
So what is control line? Control line models are generally flown on two control wires attached at one end to a bellcrank that is rigidly fixed inside the model and to the other end a very simple U shaped handle that is held by the pilot. The bellcrank has a pushrod attached to it and at the other end the pushrod is attached via a small horn to the elevator. When the model is flying the control wires will be tight so any movement of the handle will then correspondingly move the bellcrank- which in turn moves the elevator. This sounds complicated but in practice is very simple.
Control line models are powered by either glowplug or diesel model engines (and these days even electric motors) – typically will be of 2.5cc size or upwards. The larger model engines generally are used in the aerobatic type models.
There is a great variance in the control line model types being flown and they range from trainer models, combat, aerobatics, teamrace, speed, and to a more complex type called scale.
The trainer model is a very simple, quick to build, and more importantly quick to repair….its sole purpose is that of teaching a pilot the art of control line flying so it must also be a good flying model.
The combat models are interesting as the object is to cut off your opponents streamer…yes, two models are flown in the same circle by their pilots and each towing a paper streamer. The object is to pursue ones opponent and to cut off as much as possible from his streamer with the propeller. Over enthusiasm on the part of the pilots sometimes leads to spectacular mid-air collisions.
Aerobatic models are designed to perform quite complicated manoeuvres such as loops, inverted flight, vertical and overhead figure eights. These models are generally quite large and are very elegant in shape. Very considerable skill and judgment are required in successfully flying this type of model through an elaborate series of manoeuvres.
The teamrace models are designed for racing and two or three models are flown in the same circle simultaneously, the object being to cover a given number of laps in the shortest possible time. However there is a catch- the maximum sized fuel tank will require the competitor to have pit stops for refuelling so aside from the model speed there is the time lost for the refuelling; and both of those items contribute towards the final end result. These models can be scale in appearance although in recent times the models became very ‘abstract’ and no longer look like real aircraft.
Speed models are designed with one thing in mind- and of course that is to go very fast. These models are quite small and have been designed to reduce any form of aeronautical drag….any drag will slow the model down. The engines are very high revving and it is not uncommon to see the use of a single bladed propeller; and yes they are efficient. This type of event can be quite complicated and is generally for the more experienced modeler.
Scale control line models are among the most impressive looking of model aircraft- they are, as the name suggests scale models of actual full size aircraft. The work involved in making scale models is very large and this type of model is generally for the very experienced flier and modeler. Items that the modeler will make can relate to working retractable undercarriages, lights, cockpit details, and the list goes on…….certainly this type of model is not for the beginner!