Imagine the perfect geometry of the loop as you look skyward directly in front of yourself, that is, see the shape of a constant radius that begins with the wings level at a good height and then a gentle pull back on the elevator to initiate the first ¼ of the loop. As it begins the ascent it might have a tendency to get off heading and start to corkscrew or drift in toward you or drift out away from you. You want to use only slight pressure on the rudder to yaw the aircraft and maintain the imagined perfect geometry that I mentioned in the last sentence. Once you have set the elevator pressure to scribe the first ¼ loop you must maintain that very same shape for the duration of the loop. That means that as the aircraft finishes the first ¼ loop you might have to release the elevator ever so slightly to achieve the vertical climb necessary to duplicate the geometry of the first quarter loop and maintain the proper heading even as the aircraft is pulled by the p factor of the propeller to the left. Constantly pressurizing the rudder to maintain the proper heading and working the throttle to keep the speed up and avoiding any flat spots that have a tendency to occur when all of this is going on….this is the challenge.
As your aircraft begins to reach apogee, or the top of the loop, more throttle control is essential and a different touch on the elevator is required. You want to reduce substantially the power as you reach 12 o’clock noon and you actually will be thinking about floating it over the top and letting gravity do its work. As the imagined geometry continues into the next quadrant of the loop the radius shape and size must be maintained and the pressure on the rudder will be less intense due to the power off setting. No flat spots or changes in the radius should be occurring at any time and as the aircraft reaches the 3 o clock with the third quadrant complete the throttle setting needs to be increased somewhat to maintain the flow through the fourth quadrant of the loop. If, at this time, you have pictured your loop geometry in your mind’s eye you will see the entry point of the loop, that point which initiated the beginning of this loop coming up and you will want to scribe the last quadrant so as to reach that juncture precisely and at the same elevation that you began the loop. As the throttle is applied the aircraft will have its tendencies to pull to the left from the torque of the motor and this will occur anytime you apply power. As you finish the loop try to maintain a leveling off to horizontal flight without the very ugly and lame porpoising up and down.
The complete loop, done as described above, is beautiful and impressive and it is the essential building block of much of what is done in precision aerobatics. Think for a moment, anytime you leave level flight you are performing a one quarter loop or a one eighth loop to begin an up line or a 45 degree up line and any figure that is completed to get to horizontal flight is the same. These looping portions are all important in contest flying and it is the building block of much of what good pilots do without much thought, that is, it just starts to become natural to watch every looping portion to keep it under control and avoid change in radius and flat spots. Matching quarter loops and doing 5/8’s and 3 / 4 loops with constant radius are going to occur over and over again and you need to develop an eye for those geometric shapes in all areas of the aerobatic box….i.e. The sky in front of you.
When you have practiced this over until you can keep a reasonable control of the loop throughout the loop in front of yourself then move it to the left and right of center. Next, try a roll at the apogee of the loop and maintain the radius shape as you do it. After that you might want to try doing an outside loop, that is, enter the loop from inverted flight and practice maintaining the constant radius and all that I have talked about throughout the outside loop. Challenge yourself by trying to do two loops that are exactly identical in front of you….inside and then outside and then if you need more of a challenge for yourself and you are ready for it then do the loops from the top….start high and exit high. The challenges are endless that can be applied. See in the attached aresti drawing what a simple to complex loop can be. Hope you will try this and I hope that you will find success. Feel free to approach me or any IMAC pilot to critique your efforts and give you feed back on the quality of your loops.