Olympic Mk VI - Control line stunt twin-rudder model. For .35 power.
Quote: "On the Mark VI Olympic I have used an 18% thick airfoil with max thickness at 30% of root chord. At the tips, 19% with maximum thickness at 25%. Looking at the shape of a non-symmetrical section of a light plane, when viewed from the trailing edges, both tips are washed out (bent up). This is done so that when the aircraft is at its rated stalling speed, the tips have not reached stall angle and stability with relation to the roll axis remains. To achieve this same effect with a symmetrical airfoil, the thickness percentage at the tips is greater than inboard with the maximum section closer to the leading edge. Therefore the tips stall last or at a higher angle of attack assuring some tip lift to resist engine torque. To prove this point, while flying one of my older Mark II Olympics I let the engine quit while the plane was quite high. During the landing approach I gave excessive up control to stall the airplane. I experienced a very severe roll, first toward me and then away. With the improved airfoil, my Mark V can be stalled with the only effect being an extremely mushy approach.
On the plans I have offered an alternate type of landing gear. The first design series used the fuselage gear incorporating a torsion principle which does a fine job of absorbing landing shocks. Its drawback was that when the gear was loaded as in a bump, it returned with authority driving the plane back into the air. This occurs on hard surfaces, not on a grass field. If the majority of your flying is off the grass, the torsion gear is then best for you.
On the Mark VI I switched to the swept-in wing mounted gear in my search for better landing ability on hard surfaces. When flexing to absorb the shock of landing, the gear has to be in a position which will not transfer the shock into the plane. If you trace this shock line, you will find that the straight-ahead gear has to spring forward to absorb this shock and has to flex farther for a given amount of load. With the swept-in gear, the motion of the gear is 90deg to the shock line and its movement is not as great for the same amount of load. The secret is that the shock line is not straight up but somewhere around 45deg. Most straight-ahead gears are at an angle of 45deg and in direct alignment with the bump load.
A slightly stiffer gear has to be used in the wing for good ground stability. It also tolerates a much faster landing speed..."
From American Modeler Annual 1963.
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