“Made without balsa? Then bad!” — is unexceptional opinion about aerobatic traditionally there is a perception among most athletes. Especially categorical estimate the model from the point of view of its material beginners — experienced only pilots first, to clarify, do not use fiberglass.Maybe you shouldn’t be so categorical in his judgments
only “dress for success”? Ultimately, all flight properties of the model do not depend on the used materials, the main thing — successful, from a design point of view, a well-designed power and aerodynamic configuration.
An example of this is the proposed flight, which can be collected even on the kitchen table from readily available materials.
To reduce the forces that prevent the rapid reversal in the “corners” of the square shapes of the complex, is the task we tried to solve when designing this model. Here’s how we reasoned. If aerodynamic effects have a double impact on the accuracy of sharp reversal, then a significant separation of the masses only harmful. Aerodynamic damping makes it difficult to rotate the model, but it also helps dramatically to stop the rapid rotation after the transfer of the rudders in neutral. Imagine the impact of the spacing of the masses can, trying to spin and quickly stop the long rail. While she hung, will make it easy. But as soon as the ends appear a small additional loads (even much lighter than the weight of the rack), the hand will immediately feel the difference. The same happens on the model. Adjusting the elongation of the fore part, carrier motor, or a dozen extra grams on the tail completely changing the nature of governance. Pilotage not only be “sluggish” with a sharp cottage rudders — it is much more difficult to stop the rotation started, she did not immediately go into a straight flight after the rudder is in the neutral position. To what extent can seemingly save the day, shifting the CG back, that is, decreasing the stability margin at the angle of attack. But look where it leads: an additional download of a tail part will exacerbate the effect of the spacing of the masses, and a heavy engine will be at a greater distance from the center of gravity of the model. As a result, the controllability is not improved, and the stability of the apparatus during slow withdrawal from the figures in the direct flight will decrease, management will become more difficult.
Fig. 1. An aerobatic control line model airplane.
We came to the conclusion that it is necessary to significantly shorten the nose of the fuselage and simultaneously reduce to the limit the weight of the tail. We also considered that the impact of the spacing of the masses is primarily determined by the distance between the centre of gravity within the formula of moment of inertia in the second degree.