rcplanefan

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Those of you interested in flying IMAC next year in Basic or in Sportsman might have an interest in this. Here are some narratives covering flights through the 2007 sequences. These narratives were not meant to be the "only" way to fly the sequences, merely a guide to help a new person get started. You can find them on the home page of the IMAC website:

http://www.mini-iac.com/DesktopDefault.aspx

I tried to attach the files here, but unfortunately RCU doesn't support uploading of PDF's. I'll try to paste the text into some follow up posts here.

Questions? Comments? Is this helpful?

Ken

BTW - BIG thanks to Anna Wood for all the website work and updates. Anna is putting in significant time on the IMAC website - everyone thank her for all her work!

rcplanefan

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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.

rcplanefan

My Feedback: (2)

Sportsman

This narrative was designed to aid the Sportsman Class IMAC competitor in a flight through the Sportsman 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 Sportsman 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 Sportsman 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 that allows you to gain sufficient altitude for the first figure such as an Immelman. 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 judge’s 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 – Goldfish. Near the center of the box, reduce throttle to idle, and execute a gentle push to a 45 degree upright downline. After holding this line for a short time, complete one complete snap roll. For the single snap, you may want to increase the throttle 1-2 clicks just prior to executing the snap to get good airflow over the flying surfaces and allow the plane to come out online. Hold the line after the snap to make it the same length as the line before, and then begin a gentle ¾ loop. As you near the bottom of the loop, gradually increase throttle until you have reached full throttle as the plane nears vertical. As you come over the top of the loop, smoothly reduce power back to idle. To make the Goldfish geometry better, pay very careful attention to the wings as you come over the top of the loop and INSURE that they are level. This makes the 45 degree downline much less stressful as you will be online. Hold an inverted 45 degree downline (not too shallow – a common mistake for the beginning IMAC pilot) and then execute a half-roll to upright. You likely will not have to input any rudder during this roll. Hold the line making it equal in length to the line before the half roll. Execute a gentle pull to horizontal, level flight, and increase power.

Figure 2 – Outside Half Loop. Fly past center (you may well finish the Goldfish past center anyway), increase power to full, and complete two quarter rolls (2-of-4 point) to inverted. You should have to give top rudder (right rudder if you rolled left) during the first point, and down elevator once inverted. Make sure your wings are level but don’t draw a line (downgrade), and then begin a gentle push for the outside half loop. Many pilots will push hard to avoid the earth – but a gentle push here will make the figure smooth and give you sufficient altitude for the upcoming spin. Finish the half loop upright, up high, and reduce the power smoothly as you setup for the spin. Do not let the airplane descend during this line – this will take practice and you may want to have someone standing next to you telling you if the airplane is descending.

Figure 3 – Down Teardrop. 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. Hold the downline for a moment, and then begin a gentle pull for the 5/8 inside loop. As you pass through the bottom of the loop, smoothly increase power to full and once you reach the inverted 45 degree upline, hold that line. You should be giving some down elevator to hold the line. As you complete the half roll to upright, relax the down elevator. Hold the line after the half roll until it is the same length of the line before and then gradually execute a gentle push to horizontal, level flight. Begin smoothly reducing power for the next figure, and insure that the plane does not descend during this line.

Figure 4 – Vertical Downline. Once you reach the right end of the field, reduce power to idle and allow the plane to slow. Execute a gentle push to a vertical downline and hold that line for a moment. Complete a half roll so that you are looking at the top of the airplane, hold that line to make it the same length as the line before the roll, and then execute a gentle pull to horizontal, level flight while increasing throttle. The key to this figure is to start high and execute GENTLE radii top and bottom to demonstrate the control you have over the airplane as the ground is rushing up to meet you.

Figure 5 – Cross-box Humpty Bump. This figure gives you the option of either bringing the airplane in closer to you or moving it farther out. It will probably present better to the judges if you take this figure out, but if you are finding yourself way out before you start this figure, bring it in. I will describe this figure going OUT. Just prior to the center of the box, increase power to full, and complete a gentle pull to a vertical upline. Insure that this line is vertical before doing any rolling or you will be fighting the line all the way up. Hold the line; execute 2 points of an 8 point roll to the left (concentrate on stopping the first point right at 45 degrees to reduce downgrades). You will now be looking at the top of the airplane. Hold the line to make line segments before and after the roll equal in length, and then begin a gentle push for a half outside loop across the top. Reduce power to idle as you pass over the top and check to insure your wings are level to make the downline nice and straight. Hold this line for a moment, complete ¾ roll to the right and hold that line to make the line segments equal in length. Finally, execute a gentle pull to horizontal, level flight while gradually increasing power. You should be flying towards the left end of the field.

Figure 6 – Half Cuban 8. As you near the left end of the field, increase power to full and complete a two-point roll. Give down elevator while inverted to keep the plane from descending. Once you reach upright, immediately begin a gentle pull. Insure that you end the two-point roll with wings level to make the pull easier. As you come over the top of the loop, you will need to keep the power on longer than normal because you will be coming back into the wind. You may even need to hold some down elevator across the top to keep that radius nice and round. As you approach the 45 degree inverted downline, smoothly reduce power to idle. Hold the 45 degree line for a moment (not too shallow), and then complete a 2-of-4 point roll. You should not need rudder while in knife edge, and frequently if it is used, it makes the roll come off line. Just hesitate for a moment in knife edge and then complete the next quarter roll to upright. Hold the line long enough to keep line segments equal in length (don’t get shallow here), and then complete a gentle pull to upright while smoothly increasing throttle.

Figure 7 - Hammerhead. Fly towards the right end of the field, increase power to full, and complete a smooth quarter loop to a vertical upline. BEFORE the pull, make sure the wings are level to make the upline straighter (this is important every time, but especially when there is a rolling element on the upline). Hold this line for a moment, and then complete a full roll. Hold the line after the roll to make it the same length prior to the hammer. Reduce power, but 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.

Figure 8 - Loop. Although centering a figure is not a judging criteria, figures like loops are generally designed in the sequence to present best if flown center box. As you exit the Hammerhead and approach center field, increase power to full throttle. Begin with a gentle pull into the loop. Keep the power on as you near the top of the loop. Relax the elevator just prior to the top and complete a full roll. The roll should be centered on the top of the loop and should be incorporated into its radius. This is easier than it sounds if you just roll somewhat slowly and don’t use anything but aileron. The plane will naturally drop its nose as it goes through the top of the loop. Practice with loop size and roll rate will make this figure work well without worrying about rudder during the roll. As you complete the roll, smoothly reduce power to idle (if you “chop” the throttle, the radius of the loop will surely change – particularly since you are now flying into the wind) and complete the loop. As you finish the loop, smoothly increase power.

Figure 9 - Teardrop. As you reach the left end of the field, increase power to full, and execute a gentle pull to an upright 45 degree upline. Hold this line to gain sufficient altitude, and then complete a 5/8 inside loop to a vertical downline. As you come over the top of the loop, you will probably have to keep power on to keep the radius the same as you come back into the wind. As you approach the vertical downline, smoothly reduce power to idle. Hold a vertical downline for a moment, and complete 2 points of a 4 point roll. Hold another vertical downline to make the line segments equal, and execute a gentle pull to level, horizontal flight as you gradually increase power.

Figure 10 - 180 Degree Aerobatic Turn. Here is another figure that allows you to either bring the airplane back in towards the flightline or go out away from the flightline. Most pilots will likely choose to take the plane out, so I will describe that here. After you pass the center of the field, increase power to full. Quickly roll to about a 60 or 70 degree bank angle, and add up elevator to establish a banked turn. By holding the correct amount of elevator, you should be able to maintain both bank angle and turn radius throughout the 180 degree turn. After you have completed 180 degrees of turn, roll the wings back to horizontal. Fly 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.

Zeeb

My Feedback: (41)

I really appreciate this sort of help in getting into the IMAC stuff. While I've gotten enough of the Aresti down to read the new ones, I like to wait for a narrative from the IMAC website. There are a number of guys around here who fly IMAC and most are quite willing to help, but there are some differences in how these folks describe manuevers and not many who can/will tell you what to watch for on downgrades.

It also helps since I'm trying to generate more interest in our club toward IMAC stuff and it helps when I point interested club members to the IMAC website, to have the sequences in a narrative so the Aresti doesn't scare them off...

So, Thanks a bunch Ken!

rcplanefan

My Feedback: (2)

No problem, Zeeb. It's all about fun in the end - I hope this helps some new folks to get more interested.

Ken

3Dreaming

My Feedback: (1)

Ken, thanks for the narrative. I know you say you are using form B, but you might state on figure 1 the direction you are flying. I was flying the sequence in my head as I read along, and it wasn't until figure 5 when you said roll left for the canopy facing you that I realized I was going the wrong direction. Tom