EMAC Pilots & Planes

2 posts

Precision Aerobatics

The neat thing about getting into this is that any aircraft that is straight and set up correctly will allow you to practice these things anytime you want, adding little things to your repertoire until you are able to do a number of really nice looking figures.  The basic figures that comprise the beginner level are really simply horizontal lines, vertical lines, 45 degree lines, simple axial rolls, and then spins and stall turns to provide a bit of spice. 
When you have soloed and you have moved up to more challenging aircraft…perhaps a low wing tail dragger.  Take offs and landings are in the bag so to speak and you are looking for new things to try then pilots frequently are caught rolling and looping and keeping good control of the aircraft all of the time and they begin to watch what others are doing with their aircraft.  Often times you will be impressed by someone who seems to be disciplined and is trying new things.  You want to go there too but you do not know  how to get on that road.
The road begins with watching the action at the field and picking out certain aircraft that you like the look of and can afford…both time and moneywise and talk to those that are flying these aircraft.  Many new aerobatic planes exist on the market and asking questions about them is a terrific idea.  One club member that comes to my mind is Craig Hunter who approached me repeatedly when I was flying a Fliton Extra 330 and plied me with questions about this and that and took pictures and asked how I liked the plane.  This went on for quite a while and I was wondering if it would come together and sure enough I know that he is successfully using that very good airplane to practice precision aerobatics. 
Once an aircraft has your fancy and you think it will fly straight then the next thing you must do is put it together correctly with the best servos and dependable power system that you can afford and begin to fly it and watch what it is doing when you try to fly straight lines of all types.  Here’s the thing:  light weight means a light wing loading…..a very good thing…., you must then get the center of gravity correct, you must get the thrust lines correct, and you must get the control throws correct.   When these are achieved you will be amazed at how much pleasure you will get from flying that aircraft.  Small airplanes are at a disadvantage because they tend to jump around a bit and seem to flit around instead of groove through aerobatic maneuvers.  The larger the aircraft the more solid it feels through turbulence because of the higher Reynolds Numbers.  RN is the laminar flow principles that air produces as it flows through or around an object.
Google it if you would like to find out more about RN.

This installment, as you noticed,  is all about the important questions…..do you want to fly smoothly and do you have the right tool for the job?   Once you get past these two in the affirmative then the next stage in development is to try to trim the aircraft to fly straight and level without touching the sticks….(once in level flight).  There is so much to learn in setting up a good aircraft but when you do have one set up and you like the feel of it in flight then you are ready to try loops that have constant radius throughout and slow rolls that require small inputs on rudder and elevator to hold the heading and roll rate constant.  Think about flying the nose of the aircraft and making your rudder and elevator guide the nose at all times by pressurizing those two surfaces.  There is nothing more excellent and exciting then to see a brilliantly performed slow roll from one end of the field to the other.  Once you learn to do them then rolling loops and circles are just around the corner.



The Perfect: LOOP

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.




IMAC loop Diagrams