BASIC

This narrative was designed to aid the beginning IMAC competitor in a flight through the Basic sequence. It is not the intent of this article to be all encompassing in terms of judging criteria or the great benefits of learning how to read the aerobatic shorthand – Aresti. For more complete information in reading Aresti, follow this link:
http://www.flyinggiants.com/forums/f...de-simple.html

It is highly recommended that if you have not trimmed your aerobatic model for neutral flight that you work through Peter Goldsmith’s trimming method prior to flying the sequence. A properly trimmed model is much easier to fly and will drastically reduce your workload as you perfect the sequence. A link to Peter’s article can be found on the left side of this page:
http://www.mini-iac.com/DesktopDefault.aspx?tabid=70

Now that you are flying a well trimmed model, let’s step through the Basic sequence. IMAC does not require that the sequence be flown into the wind, but it is strongly suggested that you prepare to fly the sequence in both directions – you never know which way the wind will be blowing on any given day at an event. So be prepared for both! This article will assume that the wind is blowing from right to left (as shown in form “B” of the Aresti chart which can be found on the IMAC homepage).

Take off into the wind. The Basic sequence starts into the wind, so make a 180 degree turn at the end of the field, and pass back in front of where you are standing. Once you get to the left end of the field, perform a simple turnaround maneuver such as a ½ reverse Cuban 8 so that you are coming back towards the center of the field with the plane right side up. You should try to be out 100-200 feet and flying parallel to the runway. Once you get near the center of the field, have your caller tell the judges that you are “in the box.” You’ll want to do this 2 to 3 seconds before beginning the first figure (this gives the judges time to start judging!). From here until the end of the sequence, you are being judged, so get those wings level BEFORE you call the box.

Figure 1 – Roll. Just before you get to the center of the box, start an aileron roll. You will not be judged on the rate of the roll – it can be as fast or as slow as you like. Typically, the faster you roll, the harder it is to stop it with the wings level. Give a little down elevator while you are inverted so that you don’t lose altitude, and stop the roll with your wings level. As soon as your wings get level and you complete the roll, your score for this figure is set. However, you will continue to be judged as you fly to the right end of the box so KEEP YOUR WINGS LEVEL and don’t climb or descend. Any deviation on this line will be reflected in downgrades applied to the second maneuver.

Figure 2 – Humpty Bump. As you get to the right end of the field, pull a gentle radius to a vertical upline. As you establish this line, use your rudder to keep the plane tracking straight up. Remember that in IMAC, you are judged on the TRACK of the airplane and not its ATTITUDE. So you may have to crab into the wind (with rudder) to maintain a nice vertical line. Once you have gained sufficient altitude, pull a nice gentle radius over the top to a vertical downline and reduce your throttle to idle as you come over the top of the half loop. You should now be looking at the bottom of the airplane as it flies straight down. Be careful as you pull across the top of the half loop to keep the wings level as this will make the downline straighter. Once the airplane has flown down a short ways, complete a half roll. Draw another short line, and then execute a gentle pull back to horizontal flight and bring the throttle back up. For best score, the lengths of the two lines before and after the half roll should be equal. The airplane should now be headed back towards the center of the field parallel to the runway. As you approach the center of the box, you may notice that the plane has drifted in or out compared to where you started the sequence. You should practice holding the appropriate crab angle through these figures if there is a cross-wind or expect a downgrade if you have to correct your line later.

Figure 3 – Reverse Sharks Tooth. Fly a short ways past the center of the field, increase the throttle to full power, and execute a gentle pull to a 45 degree upline. Hold this line for a bit, and then execute a half roll to inverted. You will probably need to hold down elevator to keep this line straight. Use your rudder to keep the plane on track (this will be hard as you will be looking at the back of the plane while it is upside down – practice!) and keep the wings level. Once you have executed a short line while inverted, pull a gentle radius over the top of the figure to a vertical downline and reduce throttle to idle. Complete a straight downline and then execute a gentle pull to horizontal, wings level flight and increase the throttle. You should now be headed back towards the center of the field parallel to the runway from left to right.

Figure 4 – Teardrop. This figure begins with a vertical upline. It will be easiest to perform right in front of yourself. Increase the throttle to full power and pull a gentle quarter loop to a vertical upline. This figure will require power, so it is best to increase the throttle to full power before pulling. Execute a nice, straight upline in the center of the box using rudder to keep the plane tracking straight up. After gaining sufficient altitude, execute 5/8 of a loop across the top of the teardrop to an upright 45 degree downline. Smoothly reduce the throttle to idle as you come over the top of the loop. Hold that 45 degree downline for a while. Many new IMAC pilots will make this line WAY too shallow – keep this in mind and make your 45 degree line 45 degrees! Finally, execute a gentle pull to horizontal flight and increase the throttle. Fly to the right end of the field.

Figure 5 – Hammerhead. Begin this figure by applying full throttle and executing a gentle pull to a vertical upline. Again, use the rudder to keep the plane tracking straight up. Once you have reached sufficient altitude, begin to decrease the power. Leave 3 or 4 clicks of power on, and just before the plane stops moving, apply full rudder. It is almost always easiest to hammer INTO the wind if there is a cross-wind. If the wind is down the runway, hammering either left or right is OK. Once the plane starts to pivot, the throttle can be reduced to idle. One method of preventing the plane from wagging its tail after the pivot is to keep some rudder input after the pivot and slowly take it out as the plane goes down. At the bottom of the line, execute a gentle pull to a horizontal exit and increase the throttle. Try to make the entry radius and exit radius equal – don’t execute a sharp pull at the bottom. You should now be flying back to the center from right to left parallel to the runway.

Figure 6 – Loop. This figure looks easy and is probably the first aerobatic maneuver you flew when learning to fly. It is, however, extremely difficult to fly well. Begin by increasing the throttle to full power, and start a gentle pull. The size of the loop is not judged, but the bigger the loop, the harder it is to make perfect. Keep the radius consistent and wind correct with rudder if necessary as you execute the first half of the loop. As you come over the top, you may need to keep a fair amount of power as this portion will be flown into the wind. You may even need to apply some down elevator across the top of the loop to keep it round. As the plane starts down the backside of the loop, decrease power smoothly to idle and use the elevator to keep the radius consistent. Finally, increase the power as you come back to horizontal flight. The loop should start and stop in the same place at the same altitude! Fly toward the left end of the field.

Figure 7 - Half Cuban 8. Begin by increasing the throttle to full power and execute a smooth 5/8 inside loop. Again, as you come over the top of this figure, you may need to keep a lot of power as you will be flying into the wind. As you approach the inverted 45 degree line back towards yourself, decrease the power to idle and hold some down elevator to maintain a nice line. Most newcomers make this line too shallow, so concentrate on getting the line correct. After holding the 45 degree line for a bit, execute a half roll to upright and maintain the 45 degree line. Finally, execute a gentle pull to horizontal flight and increase the throttle. You should now be flying back towards the center of the field from left to right parallel to the runway.

Figure 8 - Sharks Tooth. Fly towards the right end of the field, and increase power to full throttle. Execute a gentle pull to a vertical upline. As before, use the rudder to maintain a nice vertical track. Execute a gentle pull across the top of the figure to an inverted 45 degree downline coming back towards yourself and decrease the power to idle. Hold down elevator to maintain a nice line (not too shallow!) and then complete a half roll to upright. Hold this line and then execute a gentle pull back to horizontal flight and increase the throttle. You should be flying from right to left parallel to the runway.

Figure 9 - Immelman. This figure is used to gain altitude for the final figure – the spin. So make sure the radius is big enough for the spin that follows. Fly towards the left end of the box, increase power, and begin a nice, round half loop. As you approach the top of the loop, you will likely have to feed in some down elevator as you come back into the wind and keep the power on! Immediately after reaching horizontal, inverted flight, complete a half roll back to upright. Do not let the plane descend between the end of this figure and the spin – a very common mistake. Reduce the power a bit after this figure to give yourself time to set the spin up.

Figure 10 - One and a half turn positive spin. As you approach the center of the field at a high altitude, begin to reduce the throttle smoothly. As the plane slows, you will have to feed in up elevator to keep it from descending. This will gradually bring the nose up. Once the throttle has reached idle, keep feeding in up elevator until the nose drops in a stall. You will also have to be keeping the line straight with rudder – particularly if there is any crosswind and your airspeed decreases. Don’t worry if the nose of the plane is cocked 45 degrees before the stall – it is most important to keep the line straight! As the nose drops, feed in rudder in the same direction as the wing that is falling – right rudder if the right wing is falling and left rudder if the left wing is falling. Once the spin begins, go to full rudder and full aileron in the same direction (you should already be at full up elevator). After 1.5 turns, neutralize all controls to stop the spin. If the nose is high, give down elevator to establish a vertical downline. After the downline has been established, execute a gentle pull to horizontal flight and increase the throttle. You should now be flying from right to left parallel to the runway. After you have flown a short line, wag your wings and have your caller tell the judges you are “out of the box.”

Take a deep breath, fly a couple of passes back and forth (with simple turnaround maneuvers at each end) and do it all again.