Piccolo Electric Heli, Hints and Tips pageSee the Low Flight Time Troubleshooting Guide if you are having problems with abnormally low flight times.If you are having Piccoboard problems, see the Piccoboard identification page, the Repair page and the Piccoboard Troubleshooting page. For information on converting the piccolo to brushless operation (more power and longer flight time), see the Brushless conversion section, and the Main motor and Tail motor topics here.
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| General A starting point Carrying case Flybarless COLLECTIVE PITCH modification! Ikarus collective pitch modification kit Low power and/or flight time issues The Piccolo and weight.... please read! |
Trim, balance and setup Trim Balance Tracking Throttle setup Rudder channel and gyro setup Collective pitch throttle curve setup Piccoboard Heading Hold module setup |
| Batteries Batteries and battery life Lithium cells Battery connector Battery mounting Battery charging Battery chargers |
Radio and electronics Piccoboard identification Piccoboard repair service Piccoboard and Piccoboard gyro troubleshooting Piccoboard Gyro Issues Servos and glitches Single conversion vs. dual conversion Receiver crystals Positive vs. negative "shift" Range check Rudder trim drift / zero point initialization Transmitter throttle "clicker" Piccoboard with separate tail ESC High frequency tail ESCs |
| Main rotor and head/swashplate Ball links Rotor hub and those pesky disappearing bearings! Main rotor blade attachment modification Rotor head stiffener brace Rotor blade modifications Swashplate modifications Aftermarket carbon fiber blades |
Tail rotor system Tail rotor gear attachment Tail wagging |
| Motors Main motor Tail motor Tail motor with > 7 cells Piccoboard with separate tail ESC |
Gearing Gearing |
| Repairs Piccolo Repairs Piccoboard repair |
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| A starting point You have some choices when building and outfitting your Piccolo and they can be confusing if you are new to helis and in particular to electric aircraft. Since some of these choices have a large impact on how well and how long the Piccolo flies, I have listed a good starting point for the newcomer to the Piccolo. Later on you can deviate, but for starters, try the following setup and you should have no problem getting your Piccolo off the ground for 4-5 minutes (if your flying skills are up to it, that is!). Battery: 7 cell Panasonic AAA NiCd (See Battery section for source) Gearing: Main motor, use the 9 tooth pinion (the middle one) Tail motor, use the 8 tooth pinion (the small one) Read the throttle setup FAQ topic Break the motor in for an hour or two on 3-4 volts (2 cells) with no load Your heli should weigh about 160 grams without the battery, and about 230 grams with it With the above setup, the Piccolo should fly well. Now, read on for lots of stuff to try! Servos and glitches The Piccolo is a very well thought out product... with one major exception. The BEC output of the Piccoboard is rated at 800 mA PEAK. This output has to run not only the receiver but also both servos. When I first powered up my Piccolo, I had massive glitching that I initially blamed on the receiver. However, some experimentation revealed that the problem was the fact that the servos I was using required approximately 900 mA peak EACH. The BEC output (nominally 4.5V to 5V) could be observed on an oscilloscope to drop to as low as 2.5V or lower when both servos moved at the same time. Somewhere around 2.5 V. is the point where either the receiver or the servos develop problems, and anything below that is guaranteed trouble. In desperation, I made a crude current shunt and measured the peak current demand from several brands of servos (Picco, GWS, Expert) and they ALL drew between 600 and 900 mA peak (in small current spikes of approx. 50 uS, each time the motor fired). With all these servos, these current spikes were enough to cause the BEC output to drop below 2.5 V. and cause severe glitching. Remember that the BEC output also powers the receiver. In the end, I found that Hitec HS-50 servos are acceptably light and while they draw a peak current of approximately 550 mA each, they do not load the BEC output enough to cause glitching. The BEC output DOES still drop, but not below about 3V. I have been flying the Piccolo for months now with HS-50's and have had a very occasional momentary glitch that I am relatively certain is radio-related (momentary and does not repeat). Use other servos at your own risk, and test carefully! By the way, in this application, I think we are looking for servos that are slow rather than fast. We don't really need the speed, and and the slower they are the less current they may draw. But speed is not the real determining factor. It also depends on the motor used and what it's stall current is. That is because whenever the servo tries to move the motor when it is initially at rest, the motor is in effect stalled for the first few microseconds and draws current equal to its stall current. This can only be measured on an oscilloscope.... the current is drawn in short pulses that a conventional ammeter will average out to a much lower value. And of course the big problem.... the peak current draw is not rated by any manufacturer, so it is a trial and error process to find servos that work. If you think you may be experiencing this problem, unplug one servo and try it. If the problem gets better (even a little) it is very likely that your servos are pulling too much current. UPDATE: April 2003 I have recently revisited the servo current issue. The new FMA PS20 servo is slightly smaller and lighter than the Hitec HS-50 that we have all used in the Piccolo for several years. I was curious to see if the PS20 was in fact suitable for Piccolo use. And the answer is.... YES! The PS20 draws even less peak current than the HS-50 (about 375 mA on 7 cells and 400 mA on 8 cells) yet is as fast or faster. Since it is also less expensive than the HS-50, we have a new contender! Single conversion receivers vs. dual conversion There is a lot of mis-information out there about the relative advantages of dual conversion vs. single conversion receivers. In short, these days a well designed and executed single conversion receiver can perform as well or better than a run of the mill dual conversion receiver. And they can perform every bit as well as ANY dual conversion receiver except for image rejection. But the key is the "well designed and executed" part. Most of the small inexpensive single conversion micro receivers offer an excellent balance of performance vs. cost. They are excellent for flying alone. However, they WILL cauase trouble if you fly near another RC transmitter on an adjacent channel or worse, fly in a situation where you are near many other transmitters. There are only a couple single conversion receivers out there that I would trust in a crowded location with RC transmitters on adjacent channels. The entire Berg line, and the JR micro receivers are very well done and I have flown my Berg6, Berg5 and Berg4 receivers in extremely crowded indoor conditions with zero glitching or interference. In fact, I flew the new Berg4 (4 channels and about 7 grams) at the last dome session with the antenna still coiled up the way it came from the factory and with the transmitter antenna about 1/3 extended with no problem at all. The Berg4 and Berg5 receivers now include digital signal processing to re-shape and replace malformed pulses, reducing the effects of interference even farther. The GWS receivers are somewhere in the middle. They are better than some, but they do get hit in crowded flying conditions. My recommendation is to avoid any receiver that might be a problem in any situation that you might find yourself in. It might cost a bit more, but the first time you crash due to a radio glitch you will wish you spent $10-$20 more and got a better receiver! Receiver crystals There has been quite a bit of confusion over what crystal to use in the Piccoboard receiver. RC receivers come in single or dual conversion configurations. I won't get into the actual differences, but suffice it to say that there are internal differences and that each design requires the crystal to be cut for a vastly different frequency even if the two receivers are to receive the same RC channel. To make matters worse, crystals are usually marked with the desired receiving frequency, not the frequency the crystal is actually cut for. In the end, it may not be possible from visually examining the crystal to tell if it is intended for operation in a single or dual conversion receiver. Symptoms such as servos that twitch but do not respond to the transmitter are a strong indication that the crystal is either on the wrong channel or is not a single conversion crystal. To my knowledge, both (all three?) receivers often supplied as part of the Piccoboard require single conversion crystals. These are NOT the same as the dual conversion crystals used with almost all commonly available "full sized" receivers. To be sure, get the crystal from the same place you get the Piccoboard or receiver, and make sure they know what receiver you will be using it in. To make matters worse, there are two different types of oscillator circuits used in small single conversion receivers, and these two oscillator circuits require different crystals also. JR and Berg receivers (and the new Ikarus receiver sold with the Pro board) can use JR or Berg crystals. Hitec receivers require a Hitec crystal. If you try to use a Hitec crystal in a JR, Berg or Ikarus receiver, you may find that your range is reduced and that you have mysterious glitching. This has nothing to do with the shift direction (see below). And in case you were wondering... the single vs. dual conversion crystal issue applies to the receiver ONLY. Positive vs. negative "shift" To add to all the confusion, we need to also pay attention to what brand of transmitter we are trying to use with the Piccoboard. Futaba and Hitec transmitters shift the carrier in a negative direction to encode data and JR and Airtronics shift it positive. These two shift modes are not compatible at the receiver. Most receivers are either manufactured for the correct shift or can be set by jumper. If your servos twitch but do not respond to the transmitter... and you are SURE that the crystal is correct.... you may have a receiver set for the wrong shift. Range check Do not expect a normal range check with the Piccolo. If you have the Berg6 receiver like I do, you can expect an antenna down range of a maximum of 30 feet before glitches begin. The problem seems to be the hash coming from the Piccoboard, sandwiched next to the receiver. I have another Berg6 that I fly in an electric airplane, and it produces completely normal (ie., 80 feet) range checks. This does not really present a problem, since you will never fly the Piccolo more than maybe 100 feet from you.... it's too small! Transmitter throttle "clicker" If you are flying with an airplane transmitter, you probably have some sort of detent device (like a clicker) on the throttle stick. While you can fly that way, the click stops will make it harder to maintain a consistent hover altitude, since you will end up hunting between two clicks. Usually, if you open the radio you will see that the throttle stick assembly has a serrated edge and there is a metal leaf spring with an edge that contacts the serrations and produces the detents. Try removing the leaf and simply turning it over so that the smooth side contacts the serrations. Or, try flattening the end that contacts the serrations. You may also have to slightly bend the spring so that it presses on the serrations more lightly. If the detents are still too noticeable, you may have to gently sand them off. Do not simply remove the spring, since you will need some drag on the stick to prevent it from flopping around. High frequency tail ESCs Due to the nature of conventional ESCs (including the Piccoboard), the tail motor will not have a satisfactory service lifetime on more than seven NiCd or NiMh or more than two LiPoly cells. To extend the tail motor life, use a high frequency tail ESC. There are currently four choices available. The JMP HF9-32 and the Wes-Tec HF100 are small (1-2 amp) controllers that are suitable for the standard tail motor with a small safety margin. The Schulze Slim-105he is a 6A controller that is suitable for any tail motor and might even be suitable for the popular Orion Elite Modified motor used as the main motor. The new TREC high frequency ESC from Dionysusdesign is a 6A with a new twist..... it includes a second input so you can program a mix ratio between the two inputs. With the TREC you can go separates even if all you have is a four channel transmitter because you can program the ESC to do the throttle to tail mixing for you. It is priced the same or less than the Schulze and defaults to a simple high frequency ESC if you do not program it. Ball links As supplied, the ball links are much too tight for good operation. In all cases except the flybar control arms, the ball links can be loosened up by snapping the links together and then gently squeezing the socket portion with a small pair of pliers as the ball is moved about in the socket. With some care, the fit can be drastically improved this way. However, the links to the flybar control arms must be so loose that they disconnect easily. This is to prevent ripping the balls off the swashplate (a US$26 part) in the event the rotor pops off. In addition, if they are not totally loose, there can be some pitch/roll coupling. I have sometimes found that merely squeezing them is not sufficient for this. What I eventually did was chuck the links in a small electric drill, and used a bit of fine sandpaper to gently sand the ball all around. When I had the ball roughed up a bit, I would then use a piece of paper towel and polish the ball with it rotating in the drill. This sounds drastic, and you have to be careful. But you can quickly get a fit that is extremely loose and disconnects easily. Try squeezing first! It's less destructive, and if you squeeze from several directions you can usually get the balls loose enough. The Piccolo and weight In an electric aircraft, and ESPECIALLY a micro helicopter, weight is everything if you are concerned about maximum performance and longest flight times. This cannot be stressed enough. The general rule of thumb is that you pay a 5 second penalty in flight time for every gram of extra weight you carry. And it adds up fast, believe me! Pay particular attention to the heavy things that are not a part of the actual Ikarus kit. These include the servos, receiver, battery pack, training gear, aftermarket bodies, or any extra hardware. For example, many folks use the Hitec HS-55 servos, but the Hitec HS-50 servos are several grams lighter. That comes out to 15-30 seconds extra flying time. The receiver is another area where you can save some weight. But be very careful when selecting the receiver if you ever plan on flying in the presence of other RC transmitters. The smallest receivers are not good near other transmitters. Here are some weight guidelines. These are not hard and fast, but they represent actual weights of my two Piccolos and their battery packs. Fixed Pitch Piccolo (with canopy), with Piccoboard and Berg6 receiver, two HS-50 servos, minus battery: 160 grams Ikarus version collective pitch Piccolo (with painted canopy), with Schulze Future 18be and JMP HF9 controllers, Ikarus Mini (not micro) Gyro, three HS-50 servos, minus battery: 198 grams Seven cell Panasonic 250 mAH AAA NiCd pack with wire and connector: 68 grams Eight cell Maxel 700 mAH AAA NiMh pack, with wire and connector: 96 grams If you are significantly over these weights, you cannot expect optimum flight times. Gearing When I put my Piccolo together, I had no idea what the best choices were for the main and tail rotor gearing. My kit had three sizes for each, and I simply chose the middle pinion for each. After a bit of experimentation, I have found that the 9 tooth tail and main rotor pinions are fine for initial flying. After cutting my main rotor blades, I find that the 9 tooth main pinion is still the best choice between power and flight times. However, I have found that the 8 tooth tail pinion is a better choice. Using the 8 tooth tail pinion, the tail motor runs noticeably cooler and will probably last longer. Note that at least on my heli, the gear mesh was not as smooth with the 8 tooth tail pinion and the lash adjustment was very critical for smooth quiet operation. If you are looking for better tail motor gears, try Todd's Models. He carries nice brass pinions with 1mm center holes, 0.5 pitch and 6-12 teeth. They work well on the Piccolo tail. Batteries and battery life The battery pack is absolutely crucial to good performance in the Piccolo. Unfortunately, the Piccolo asks more of a battery than the manufacturer "officially" designed it to do, so we are in somewhat uncharted waters... which is usually true with electric flight in general. The choices are Nickel Cadmium (NiCd), Nickel Metal Hydride (NiMh) or Lithium Ion and Lithium Polymer (LiIon and LiPoly). All chemistries have their strong points and weaknesses. NiCd cells are cheap, can be fast charged in 30 minutes or less, and have a low internal resistance which allows them to deliver their capacity efficiently at the relatively high (for the cell size) current required to fly the Piccolo. NiMh cells are almost as cheap and have a higher power to weight ratio than NiCd cells. However, they have a higher internal resistance than NiCd and you generally need to add one cell to get to the same performance compared to NiCd, which impacts the power to weight ratio. They also cannot be charged as fast as NiCd, with the average cell restricted to about a 1C (60 minute) charge. Lithium cells have the highest power to weight ratio of all, but until recently they also have had the highest internal resistance and cells that are small enough to fly in the Piccolo have generally generally been restricted to discharge currents of 2A or less which made them marginal for our use. Finally, they require a specially designed charger and can be destroyed and/or explode of charged incorrectly. See the separate Lithium Cells topic for more specific information on some new Lithium polymer cells that look promising. There are good and bad choices in all three chemistries so you should be cautious when purchasing cells for electric flight. For NiCd cells, I recommend the Panasonic P-25AAA cells. These have delivered very good performance for many Piccolo flyers and for many of us they are superior to the Sanyo cells. Unfortunately, they can also be a little hard to find in small quantities. DigiKey, a mail order electronics distributor, carries them at a good price. I used to provide a link directly to the DigiKey part, but they keep changing the location. So the best way is to go to the main DigiKey page and enter the DigiKey part number P254-ND in the search box. That will take you to the correct page for the Panasonic P-25AAA cells. For NiMh cells there are now several good choices. The Sanyo 720 mAH NiMh cells and the new Rayovac 700 mAH cells both produce good power and duration. So far, my Sanyos are holding up well and producing flights of between 10 and 12 minutes out of ground effect (with my brushless setup). I have one pack of Rayovacs, and they fly for a good 10 minutes with possibly a bit less power than the Sanyos... but not much. The Sanyos are available from several sources. I got mine from Specialized Model Supply in Crystal Lake Illinois. The Rayovacs are available in many stores that carry Rayovac batteries. I got mine at a Super K-Mart! Powerex also makes AAA NiMh cells that have been found to be good choices in Piccolo use. Note that NiMh cells may be marked with what appears to be a higher capacity than a NiCd cell of equivalent weight (and remember that weight is everything in a micro electric heli), but the real test is can they deliver that capacity at the 2.5 amps the Piccolo needs to hover with 7 or 8 cells. And there, I have found that most NiMh cells fall very short. With the notable exception of the Sanyos, Rayovacs, Maxells and Powerex my experience has not been very good so far. A second difference between NiCd and NiMh cells is the maximum allowable charge current. Once again, we are taking these cells beyond the manufacturer's design parameters. However, the typical NiCd cell can in my experience be safely charged at a 4C rate (ie., 4 times the capacity in amp hours, or 1A for a 250 mAH AAA cell) but most of the NiMh cells I have tried got very hot at anything over about 1C. There is also some indication that higher charge currents will damage NiMh cells. The bottom line is that NiCd cells can be charged much faster than NiMh. My experiences so far? I have tried 7 and 8 cell by 600 mAh NiMh (Gold Peak, I think), 7 and 8 cell AAA NiMh (Energizer) 7 and 8 cell by 250 mAh AAA NiCd (Sanyo), 7 cell by 250 mAh AAA NiCd (Panasonic), 8 cell Rayovacs and 8 cell Sanyo 720 mAH NiMh. For decent duration and fast charging, you can't beat the Panasonic P-25AAA cells. I can get solid 5 to 5.5 minute flights from the 7 cell Panasonic packs flying with stock motor and cut down rotor blades. However, for maximum duration the 8 cell packs made from Sanyo 720 mAH NiMh cells are terrific. You should get 8 minutes on a stock motor and up to 12 minutes on a brushless motor setup. The Rayovacs are also a good choice, producing consistent 10 minute flights from a brushless setup. Lithium cells Many of us have experimented with various types of Lithium cells with mixed results. Some have had very good results from surplus Qualcomm LiIon cells from cellphones. However, they have become hard to find at a reasonable price. Enter the new Korean "Kokam" and "E-Tech" lithium polymer cells. Lithium polymer cells are basically a variant on the more common lithium ion cells, but they are packaged in a plastic enclosure and have semi-solid electrolyte. They also have an improved internal structure to provide higher discharge current than any other lithium cell so far. Cells are available in various capacities, and the ones of most interest to us are the 1020 mAH cells from Kokam (good to about 3A continuous) and the 700 mAH and 1200 mAH cells from Kokam and E-Tech (good to about 6-8A). Kokam and E-Tech cells are available from Bishop Power Products. FMA Direct carries Kokams exclusively. Both types are also commonly available from many other sources. A three cell pack of the Kokam 1020 mAH cells weighs 66 grams (as opposed to over 90 grams for an 8 cell pack of 700 mAH AAA NiMh cells) and flies my collective pitch brushless Piccolo for around 23 minutes with awesome power. The E-Tech 1200 mAH cells are slightly larger and only weigh one gram more even though they are rated for more output current! But..... Lithium cells are NOT like NiCd or NiMh. They require a special charger and special care in use to prevent cell damage and/or a fire. Do NOT disregard the guidelines below. General 1. Lithium cells require a completely different charge method from NiCd and NiMh cells. They can NOT be charged on any charger not specifically designed for lithium polymer cells. They must NEVER be charged above 4.2V/cell or discharged below 3V/cell. 2. If a lithium cell is charged or discharged beyond the above voltages, it will be permanently destroyed. In severe cases, it can burst and/or catch fire. 3. Unlike NiCd and NiMh, lithium cells do not have any self balancing mechanism. Charging and using lithium cells in series requires that the user periodically monitor the individual cell voltages. Failure to do so can result in permanent cell damage and/or a fire. 4. Factory made packs are NOT necessarily in balance and MUST be checked prior to first charge and use. 5. Cells that are balanced from the factory can easily get out of balance. To stay in balance requires that each cell be IDENTICAL to the others… and this is highly unlikely in the real world. In normal use they will slowly become unbalanced. How long this takes is dependant on how well matched they were… and how well matched they remain after many cycles. Charging 1. Do not EVER attempt to charge a lithium cell with anything other than a charger specifically designed for lithium ion cells. Other chargers will destroy the cells and/or start a fire. 2. Your charge current MUST be equal to or less than the capacity of the cells. For example, a 1200 mAH pack MUST be charged at 1200 mA (1.2A) or less. 3. The charge voltage MUST be limited to 4.2V per cell. In other words, a three cell pack must be charged with the voltage limited to 4.2 X 3, or 12.6V. 4. You MUST periodically check the individual cell voltages and charge each cell individually if the voltages are not within about 0.05V of each other. Failure to do this can result in permanent cell damage and/or a fire. Discharging 1. Do not EVER (even for a short time) discharge a lithium pack below 3V/cell. This minimum voltage level must not be exceeded even under load. 2. Do not discharge a Kokam 1020 mAH cell at more than about 3A continuous. 3. Do not discharge an E-Tech 1200 mAH cell at more than about 6-8A continuous. Maintenance 1. It is essential to the long term life of your lithium pack to periodically monitor the individual cell voltages. This can be done by simply connecting a meter to the terminals of each cell and measuring the voltage. It is not necessary to disconnect the cells. 2. If the voltage on any cell in the pack is not within about 0.05V or the other cell(s), charge each cell individually. Again, it is not necessary to disconnect the cells to charge them individually if you charge one at a time. NOTE: There are several issues involved in successfully flying the Piccolo on lithiums. Lithium cells have an output voltage of between 3V and 4.2V per cell. A two cell pack will have an output voltage of between 8.4V/cell and 6V/cell depending on state of charge. A three cell pack will have an output voltage of between 12.6V/cell and 9V/cell depending on state of charge. A two cell pack (especially of the 700 mAH E-Techs) can be made to fly the Piccolo with some care and attention to overall weight. A three cell pack is a better choice BUT the tail motor life will be extremely short unless you use a separate high frequency ESC for the tail. Battery connector While I have not had trouble with the supplied battery connector, I have heard reports from others who have. However, I have noticed that it gets noticeably warm during a 1 amp charge, so I replaced mine with a three pin Dean's connector set. I used the three pin instead of the two pin because the three pin Dean's are polarized and cannot be connected backwards. Battery mounting The instructions that came with my Piccolo did not mention the electronics at all, so I had to figure out how to mount the battery pack from scratch. What I ended up with was a small plastic sling made from scrap ABS material and mounted to the main motor pinion shroud. See photo. The battery packs are made up into sticks of two cells each, mounted in a square arrangement with the battery cord coming out one end. See photo. The resulting battery pack can be slid into the sling from the rear of the heli without removing the canopy. The front of the pack has a small piece of Velcro on it that mates with a piece on a small balsa block CA'd to the underside of the radio mounting tongue. I like this arrangement much better than the Ikarus method of attaching the battery pack under the skid legs with a rubber band. Battery changes are a snap, and the CG can be adjusted easily as well. Battery charging There is considerable mis-information out there about how to charge a battery pack, so here is my contribution :) NiCd and NiMh packs are most easily charged by passing a regulated current through the pack until the pack voltage reaches a maximum and then starts to fall. This is the "peak" referred to in a peak detecting charger, and is caused by the cells going into overcharge. Cells can be fast charged or slow charged (sometimes referred to as "trickle charging"). Technically, the only difference between fast and slow charging is the charge current. However, the term "slow charge" has also come to mean a charge at the slow charge rate without any automatic charge termination, to allow all cells to come up to full charge regardless of their initial states of charge. The charge current is expressed in terms of the pack capacity. Let's take a normal NiCd Piccolo pack made up of 250 mAH cells. The pack capacity is 250 mAH. This is also expressed as "1C". A NiCd slow charge is a current equal to 1/10 the pack capacity (1/10C). NiCd cells can be safely overcharged forever at 1/10C. They will be damaged, however, by overcharging at any current greater than 1/10C. A NiMh slow charge is a current equal to 1/20 the pack capacity (1/20C). They will be damaged by overcharging at any current greater than 1/20C. The current thinking is that NiMh cells can be safely overcharged at 1/20C, but that the duration of the charge should be limited.... they should not be left on overcharge indefinitely like NiCd. A fast charge is any charge current in excess of the slow charge current. Since the cells will be damaged by overcharging at more than the slow charge current, the charge device must have a means of detecting when the cells are fully charged and must then shut off to prevent cell damage. A peak charger uses the voltage peak at full charge to determine when to shut off. A rule of thumb for NiCd cells is that they can normally be fast charged at up to four times their capacity, or 4C. This is not hard and fast, but is a good starting point for any cell that is capable of flying the Piccolo. For NiMh cells, the rule of thumb is 1C. Any more than that and the cells may get quite hot and degrade rapidly. Note that the 1C rule of thumb for NiMh is changing as cell technology changes. If you have a pack to spare, try a faster charge while monitoring the pack temperature. Just remember that a 1C charge is generally safe. Anything greater than 1C and you run the risk of degrading your packs faster than normal. Translating all this mumbo jumbo, we come up with a safe fast charge rate of 1A for 250 mAH NiCds (250 mA X 4 = 1000 mA), and 700 mA for 700 mAH NiMh packs (700 mA X 1 = 700 mA). OK, remember the slow charge I mentioned above? Here is where it comes in handy. Since all the cells in the pack are connected in series and we do not have access to each cell, we have no way of knowing if every cell in the pack is at exactly the same state of charge when we begin (or end) charging. And if they are not, the cell(s) that were at a higher state of charge when we began charging will reach full charge first. The charger is looking for the voltage peak that signals full charge, but cannot see the small peak from only one or two cells since it is expecting a larger peak from the whole pack. In this scenario, the cells that reach full charge first will go into overcharge. Since we are fast charging, they will be damaged by extended overcharge at the fast charge rate. The reverse is also true. Any cells that are at a lower state of charge than the rest of the pack will never reach full charge before the charger sees the rest of the cells peak and shuts off. This is not an uncommon condition. A new pack has cells that have never been used together before and are at an unknown state of charge. And all cells will self-discharge at varying and unpredictable rates. To equalize the cells, we slow charge the pack for a duration that is guaranteed to deliver enough current to fully charge every cell. Since we are charging at a rate that is acceptable for continuous overcharge, any cells that reached full charge before the others will not be damaged. The problem is that most chargers are designed for fast charging only and cannot be set for a slow charge WITHOUT peak detection. IF we charge at the slow charge rate on a peak detecting charger, it will shut off when it sees most of the cells peak and will not bring any stragglers up to full charge. So what to do? A simple slow charger can be made from a 12V wall adapter (the adjustable kind works even better) and a light bulb from Radio Shack. The light bulb should have a current rating approximately equal to the desired slow charge current and a voltage rating of 6V (12V may work also). Connect the bulb in series with the adapter and the battery pack and it will roughly limit the current to a value approximately equal to its rating. It is a good idea while you are at Radio Shack to also purchase an inexpensive multimeter to check the charge current. Battery chargers One of the most important things to purchase when you get into electric flight is a good charger. If you are using NiCd or NiMh cells, you should invest in a good peak detecting charger. You may pay US$100 or more, but it will be a good (and long term) investment that you can use for more than the Piccolo if you expand into other areas of electric flight. I use and highly recommend the Simprop / FMA / Dymond Super Charger. These are all the same unit with small cosmetic differences in front panel silkscreening. For about the same price as the Astro 110D, they add discharging capability and even more charge/discharge information. They will charge NiCd, NiMh and lead-acid but not lithium cells. And if space is an issue, they are considerably smaller. Currently, Dymond Modelsports in Wisconsin has the best price, at $109.00. I also use and highly recommend the Astroflight 110D digital peak charger. It is simple to use, extremely flexible, and has an excellent readout of voltage, current, time, and total charge delivered in amp hours. They sell typically for about US$110 each. It will charge NiCd and NiMh cells at an adjustable current of 100 mA to about 5A. With two chargers and three packs, you can almost fly continuously. Charge all three (or at least two) before flight. Then, when you exhaust a pack, put it on charge. By the time you have flown two packs, the first will be ready. I have a small toolbox I bought at Sears (see photo) that holds two chargers, a 7 AH gel cell, spare packs, Whatt Meter, extra props (I fly planes too), a bottle with a tube of CA in it (I don't trust a loose container of CA, and put it in a glass bottle), etc. etc. With the 7AH gel cell, I have power for about 14 or 15 Piccolo recharges. I recharge the gel cell with either a small charger I bought at Sears or an old charger from a VHS VCR. The Sears charger does not charge to as high an end voltage as the battery manufacturer recommends, but does discontinue the charge when finished. It does seem to work acceptably, though. The VCR charger charges to the correct voltage, but does not then discontinue charging as the battery manufacturer recommends. When I use it, I disconnect it when I see the charge light is off, since it is still applying the full charge voltage even though the current has dropped to near zero. Tail rotor gear attachment Unlike the main motor, the tail rotor motor shaft is a smooth non-splined shaft and the pinion needs to be cemented to stay in place. The shaft should be roughed up as best you can, and then use some thick CA (NOT thin CA, it will wick out the other end and onto your fingers and the gear teeth). I put a drop of thick CA on the end of the gear and then work it into the hole with a small piece of music wire. If this is the first time the gear is being glued, this is easy. However, if this is a repair job, the far end of the hole may be plugged and the CA may not run in of its own accord. As the CA sets, gently turn the shaft and nudge the pinion so that it turns true before the CA hardens.... the hole is larger than the shaft. Tail wagging After flying with separate components for a long time, I went back to the Piccoboard prior to setting up a second Piccolo... and ended up with a tail wag that I could not correct with gyro gain adjustments. Turned out that the Piccoboard was not firmly attached to the frame and could wiggle a little bit as the heli yawed. This induced oscillations into the system. I secured the Piccoboard to the frame with Velcro and a rubber band and the wag went away. Rotor hub and those pesky disappearing bearings! With the original design rotor hub, the bearings that the rotor head snaps on to merely slid over two posts and were free to fly off whenever the rotor head came off in a "mishap". And fly the do! There is one in my front lawn that never did reveal itself. However, the newest version of the hub that Ikarus is shipping has been slightly redesigned to allow the bearings to snap into place. The initial word is that they generally stay in place as the rotor disconnects. As of March 2001, a very generous person named Pierre is making aluminum hubs and selling them and/or giving them away for the cost of a SASE. Check out his web page. According to traffic on the Ikarus Piccolo BBS, the hub has been recently re-designed (still plastic, though) so that the bearings snap into place and do not come off in a crash. Apparently, the new hub has the same part number as the old one, and the difference is very subtle.... the end of the post is slightly enlarged. I do not know what the stock situation is at places like Horizon, so order with caution? Main rotor blade attachment modification To make blade attachment more secure and easily modified/removed, try tapping the blade holder holes to a 4-40 thread. (Photos) The existing hole is about right for a 4-40 tap, and the plastic threads easily. Now you can use a 4-40 bolt (nylon?) threaded up from the bottom to hold the blades on (with a #4 washer under the head). I have found that the bolt actually holds pretty well all by itself, but you can also put a nut on the portion that protrudes through the top of the blade holder. The blades can be adjusted and removed repeatedly and easily. And the beauty is... no Loktite required. This was actually posted on the Ikarus BBS a while back by someone who I unfortunately do not remember. Whoever you were.... thanks! Rotor head stiffener brace This is another mod I saw posted to the Ikarus BBS a while back but never tried.... until today. And all I can say is that this mod coupled with either the CF "spar" mod or Robert Fields' carbon fiber blades makes a BIG difference to stability and forward flight. The mod first requires the "main rotor blade attachment mod (above). Then, all you do is use longer bolts (don't use nylon... not strong enough) and sandwich a spacer (I used wheel collars 'cause I had 'em, but you could use plastic to save weight) under a thin piece of aluminum or carbon fiber drilled so that it fits over the bolts from above. Be careful, though. If the spacer is too short, the flybar control arms can hit the brace when with extreme cyclic input. (Photos) WOW what a difference! The coning angle is greatly reduced and forward flight is straight and predictable. Using my cut down blades and the CF spar, this mod makes a total difference in how the Piccolo flies in wind and in forward flight. Unfortunately, I managed to partially destroy Robert's CF blades while experimenting, so I can't try them with the stiffener brace. But I suspect they will fly even better, since they are a little stiffer than even the cut blades with a CF spar. Try this one and let me know how it flies. Update..... after flying with this mod and the CF "spar" mod today at the heli field in steady winds of 5-10 MPH with gusts to maybe 15 MPH, all I can say is that this is the real deal! Wow, what a difference. Yes, it was occasionally exciting. But I didn't crash... didn't even come close. And in the face of wind gusts that moved my jacket around, I flew figure eights and hovered and shot landings. All under (mostly) decent control. I took off from and landed on a small bathroom mat. It wasn't easy to hit on landing, but it was possible even in the gusts. Don't get me wrong, this is not as easy as flying indoors. But before these mods I would not have dared take off in winds like this. These mods are easy to do... what are you waiting for! Rotor blade modifications Cut blades There has been much said on the Ikarus BBS about cutting down the main rotor blades and the effect that has on flight and flight times. I have tried it myself and I can state that it does indeed increase flight times in my case by about 30 seconds. In addition, it noticeably increases the head speed, which has the effect of making the heli quicker to respond, more stable near the ground and not quite as apt to pitch up severely with wind gusts outdoors. NOTE: There have been a few reports that cutting the blades results in a heli that cannot lift off. So far, no one has really determined what the problem is, since there have been far more reports of success. For the most part, none of us live close enough to each other to get up close and personal and compare a successful heli with one that is not. My recommendation would be to purchase a spare set of blades just in case. I removed a portion of the trailing edge of the main rotor blades by making a cut (with an X-acto blade and a straight edge) beginning 3mm from the trailing edge at the tip and increasing to 8mm from the trailing edge at the root. I then used a sanding block to make sure the two blades were exactly the same width. I did not change the main motor gear ratio, and am still using the 9 tooth pinion. The head speed is noticeably faster, the control response is quicker, the hover characteristics near the ground are improved, and I get about 30 seconds more hover time. Stiffening the main blades with CF I have also experimented with adding a "spar" of carbon fiber along the underside of the blade, to stiffen it. (Photo) This seems to have improved the forward flight characteristics. I used a strip of CF tow (individual fibers). I laid it against the underside of the blade and smoothed it out near the root. I then added a drop of thin CA to attach it to the root, up against the mounting hole raised area and extending on a line towards the tip. After the CA set, I pulled it tight and smoothed the fibers so they were thin and flat, and added a drop of CA to the tip. After that set, I dribbled CA along the fibers and while it was still slightly soft, I pressed it down and smoothed it with a piece of poly sheet. I see no negative effect on flight time, even though the underside of the blade is not as smooth as it used to be. Matter of fact, this afternoon, I got a 5:45 flight with my oldest Panasonic pack and the stiffened blades. Mixed forward flight and hovering. Swashplate modifications There has recently been a lot of traffic on the Ikarus Piccolo BBS about swashplate modifications to add various forms of a ball and socket to the center pivot area. The idea is to reduce the slop inherent in the original Ikarus version of the swashplate, where the pivot point is defined by the center hole and the various linkages. Since these linkages and the center hole are somewhat sloppy, the entire swashplate can move around a bit in flight and possibly introduce slop into the cyclic. These modifications have been claimed to increase stability and reduce the tendency to wander around and pitch up in forward flight. There have even been reports of increased flight times. Some of the modifications have been very clever, but were somewhat complex. I did some head scratching and came up with my own relatively simple modification that transforms the swashplate center pivot into a ball and socket without requiring anything more than a bit of work with an X-acto knife. Note, however, that this modification will result in the swashplate being even sloppier if you decide to go back to the original version, since you will open up the center hole. A brief description is as follows.... (click here for photos) 1. Find a ball from a ball joint. The particular balls I found were Traxxas #2742 (in the car section of my local hobby shop) and have a flange on both ends. The flange has to be carefully ground off one end. You may find other balls that do not have flanges.... the critical dimensions are 3mm ID and 5mm or 6mm OD. 2. Cut a piece of fuel tubing so that when slipped over the mainshaft under the ball, the swashplate sits on the ball at the same height as before. Be careful that the added fuel tubing is not large enough to contact the stationary portion of the upper mainshaft bearing race. Because my added fuel tubing was larger than the original supplied with the Piccolo, I retained the original piece and added a larger piece on top of it as you can see in the photo. 3. Open up the center of the swash until you reach the edges of the conical portion of the center of the swashplate so that the swashplate can pivot on the ball without contacting the mainshaft. Note that all you are doing is removing the thin plastic center section. 4. Find a small spring that will slip over the mainshaft between the swashplate and the hub. Mine came from a replacement set of springs for a tailwheel assembly, but a ballpoint pen spring might fit. Cut it to a length so that when trapped between the swashplate and the hub, it exerts sufficient pressure on the swashplate to keep it seated. You don't need much pressure. Depending on the diameter of the spring, you may want a small washer between the spring and the swashplate, but make sure the washer center hole is large enough that it does not restrict the swashplate pivot. That's it. Assemble everything and re-align the flybar and fly it. You should notice much greater stability in flight and reduced wandering near the ground. Note also that the alignment of the swashplate cannot shift since everything is in compression all along the mainshaft. And don't worry about the spring adding to the servo load. The tension can be relatively light, and in my experimentation, I have found that there is negligible increased servo force required. Remember that there is NO added force at a neutral cyclic input, and very little at anything but the most extreme cyclic inputs. Aftermarket carbon fiber blades (15 October, 2000) Just got my new carbon fiber blades from Robert Lee, and in a nutshell, they are as advertised. What you get is a pair of beautifully made blades and some mounting hardware. The blades are thinner than the stock Ikarus blades, and mount under a spacer made up of two nylon washers. Robert supplies two 2.5mm bolts that go through the rotor head, the spacers, and then the blades. The assembly finishes off with a supplied steel washer and nut. Apply a bit of blue Loktite, tighten the assembly to the desired tension and you're done. (17 October, 2000) I have so far flown them outside quite a bit in calm and very light breeze conditions, and the severe pitch up in forward flight is drastically reduced. I found myself zipping around the front yard with very little pitch up tendency. Put the nose down, apply a bit of collective, and off she goes. I find that unless I get going VERY fast, there is little or no pitch up. It is of course difficult to come up with objective measurements, but I am very used to the flight characteristics of the stock and cut blades, and I immediately felt the difference. The only time there is a significant pitch up is coming out of a tight turn, and holding some gentle forward stick pressure overcomes it easily. I found myself doing figure eights that were very fast, with maybe 45 degree banks at the ends, and if I kept the tail where it belonged I could keep doing figure eights indefinitely without suddenly losing forward speed due to the pitch up like used to happen. The blades initially flew quite a ways out of track (but without much vibration). After examining things a bit I came to the conclusion that the pitch had to be slightly different for the two blades. The blades seemed to be well matched and accurately drilled, but since they are curved and mount to a flat surface, it could be possible that both blades do not always seat at exactly the same pitch. I put a couple pieces of blade covering tape on the top of the blade that flew low, just behind the blade bolt. This increased the pitch slightly and now the tracking is much better. I suspect that without bending something it will be difficult to get perfect tracking. However, there is little or no vibration and it flies great. I am getting approximately the same 5 minute flight times I was getting with my cut down blades. It is hard to directly compare, though, because I do a lot more forward flight which requires noticeably less power.... It is fun, by the way, to do a flyby and then come to a hover without changing the throttle position. It will sink quite noticeably when the forward speed drops to zero, and demonstrate transitional lift very nicely. These blades appear to be the same width as stock (ie., uncut) blades. Robert says he has tried different widths and that there was no difference in performance. But I still think it would be interesting to cut down a set similar to the cut modification some have done to the Ikarus blades. While they fly fine in forward flight, they do seem a bit more twitchy near the ground than my cut Ikarus blades... more like the stock blades. I have not been able to evaluate them in windy conditions yet (no wind so far!) but if the forward flight characteristics are any indication, they are a big improvement on the stock and/or cut Ikarus blades. And in closing, they are beautifully made too! Get your order in soon... I'd bet Robert will have trouble keeping up with orders! Main motor I have found that a standard speed 280 motor works almost exactly the same as the Ikarus motor. You might have to CA the pinion on (the shaft is not splined like the Ikarus motor) and use the next size smaller number of pinion gear teeth, and you will probably have to tap the mounting holes. But in flight, a S280 seems to be quite acceptable as a substitute. As of March 2001, I have converted my Piccolo to use the AstroFlight brushless 010 motor, the Shulze Future-18be brushless controller from RC-Direct, the Ikarus Mini-Gyro (minus case) and a "IK67108" 10 tooth pinion for the Ikarus ECO8 heli. This is a costly but stellar combination in the Piccolo! The motor just drops right in where the stock motor was with no modification required. One exception is if you use "4X2" stick battery packs like I do. In that case, the pinion grub screw will have to either be replaced or shortened so the pinion will fit lower on the motor shaft and clear the battery pack. The supplied grub screw is long enough to hit the motor mounting screw heads when fitted low on the shaft. With the brushless setup and using the 8 cell packs of Sanyo 720 mAH NiMh cells, I get between 11 and 12 minutes of flight out of ground effect! And there are a couple bonuses.... first of all, the motor is merely warm instead of too hot to touch. Second, there is power to spare all the way to about the last minute of flight. This is a very good thing for when you graduate to flying out doors. And even that last minute out of ground effect is better than the last minute of flight out of ground effect with the stock motor. The motor is more efficient and uses up the pack capacity a lot better than the stock brushed motor. Tail motor If you fly the Piccolo long enough, you will end up with a bad tail motor. Sooner rather than later if you fly on 8 cells, unfortunately. In semi-chronolical order, here is what I have discovered about the tail motor. The tail motor on the Piccolo appears to be identical to the motors used for the Wattage B2 foam indoor electric. These are available from various sources like Hobby People for about US$10.99 for a two pack, and can be used as a lower cost replacement part. See the Links and Resources page for ordering information. I have been using a B2 motor for a while and it flies identically to the Ikarus original. I have noticed that after several flights, the motor gets stiff and noticeably harder to turn. A new motor draws about 30 mA unloaded when the voltage is raised to the point where it begins to rotate. A stiff motor can draw upwards of 100 mA or more. This is wasted power and reduces flight time and increases motor temperature even farther. I believe it also contributes to sluggish rudder response too. While my B2 motors became stiff relatively quickly, my original Ikarus motor did too, just not as noticeably. The brushes in these motors are very delicate, and my suspicion is that during flight, some brush material comes off and ends up on the commutator and/or bearing, causing the rotational friction to rise. When dis-assembled, there is noticeable brush material on the inside of the end bell. I took a stiff motor apart, put a drop of Cramolin (now known as DeoxIT, a high-tech audiophile contact cleaner) on the commutator, and re-assembled it. It ran very smoothly for many flights. However, it eventually failed. Not sure if it was due to the DeoxIT or merely stress. But here's the interesting bit.... I have always had a small amount of rudder trim drift which I assumed was due to the battery pack voltage dropping during flight. However, after treating the tail motor, this trim shift all but disappeared. This would seem to confirm my suspicions that brush and comm wear and the resulting increased friction are the real cause of the rudder trim shift. How to disassemble the motor, you ask? Easy. Remove the pinion gear, carefully bend up the tabs on the rear end bell, and gently push the shaft into the motor. This will push the rear end away from the motor. Do not try to fully remove the end unless you have a good magnifying glass... the brushes are delicate and can be easily damaged if they are not carefully lifted off the commutator. However, merely pushing the end back will allow access to the commutator and allow lubrication. Use very little lube... you don't need much. And if you do remove the end all the way, put a tiny drop of lube in the bearing as well, for good measure. Eventually, I ended up running on 8 cells, and found that the tail motor lifetime was greatly reduced. Unacceptably so, in fact. So I started scratching my head and looking for another way to increase motor life. Enter the JMP HF9 high frequency ESC (available in the states from Todd's Models). (Remember by this time I am running a brushless setup with separate components, so changing the tail ESC is no problem). [Begin long explanation] The theory is that conventional ESCs (like on the Piccoboard or other small ESCs) switch the power on and off at a 1-3 KHz rate, and vary the on/off time to vary the power. Let's look at a real world example... the tail motor is running at (say) 50% power. On 8 cells, you have a total of about 10 volts available from the pack, but you need 50% power. So the ESC applies full battery voltage to the motor, but only does it 50% of the time. On the outside, the motor acts as though it was running on 5 volts. But the brushes actually see 10 volts in short bursts. This works OK in larger motors because the winding inductance can absorb the applied voltage and the actual current isn't excessive. However, small motors like our beloved tail motor have very low winding inductance and the brushes see very high current spikes that can eat them alive. And apparently do! This phenomenon has been known for a long time especially among slow fliers using coreless motors. Well, Jean-Marie Piednoir in France has designed a special ESC that has a switching frequency of 133 KHz, or about 100 times faster than a conventional ESC. At this frequency, it is possible to use very small surface mount inductors on the controller and smooth the power applied to the motor as though it was connected to a true variable DC power supply. OK, so I had to try one. And so far, it seems to have made a big difference! My latest B2 motor has flown about 10 flights so far with no stiffness and no trim shift whatsoever. The motor used to run somewhere between warm and hot. Now, after a 10 minute flight it is barely warm... not much over room temperature. It is still way to early to tell for sure, but this may well be THE answer. I'm hoping! The JMP HF9 is not without its drawbacks, but they are small ones. First, it only has 16 steps, and the tail response is not quite as precise as I was used to. But this is in fact a small problem... the gyro action seems to mask the small number of steps. Second, due apparently to its much higher operating frequency, it tends to interfere with the receiver. I had to wrap the receiver in aluminum foil to calm it down (didn't want to wrap the ESCs because they could overheat). But if it makes my tail motors last longer, I can overlook these small problems! UPDATE, 1 May, 2001: After quite a few successful flights, the motor is still OK! However, I have purchased and installed a Wes-Tecnik Micro DC5-2.4 coreless motor (available in the US from Todd's Models), and it flies great and would appear to be pretty much within its rating on the Piccolo tail, as opposed to the B2 motor which is probably being used at about 200% of design rating. The only downside of the Wes-Tec motor is that it weighs about 4 grams more and must be used with a high frequency ESC like the JMP HF9 to avoid burning the brushes. Sound familiar? UPDATE, 5 May 2001: Jean-Marie Piednoir has developed a special version of the HF9 intended for use in the piccolo. This version has 32 steps, no BEC and a faster response. To achieve 32 steps, he had to lower the operating frequency to 66 kHZ but it still outputs pure DC and FLIES GREAT! This is the one! Cool motor, smooth tail response, and best of all, NO INTERFERENCE! As of March 2002, the heli version should be availaable in the US from HomeFly.com. Or you can Email Jean-Marie in France directly at jpiednoi@club-internet.fr Ordinarily, using the HF9 requires going to separate components. However, I have discovered a simple way to extract the tail ESC signal from the Piccoboard and send it to a separate tail ESC, retining all other Piccoboard functions. See "Piccoboard with separate tail ESC". Tail motor on > 7 cells The standard tail motor is OK on 7 cells (or two LiPoly cells), but will not last as long on 8 cells or on three LiPoly cells. One solution is to change to the "high authority" tail motor, which is OK on 8 cells and three LiPolys. Another solution is to use a high frequency tail ESC. This is possible even if you use the Piccoboard for main motor and gyro/mixing. See "Piccoboard with separate tail ESC" for how to connect a separate ESC to the Piccoboard. See also High frequency tail ESCs for information on the choices available. Throttle setup If you are using the Piccoboard, it is essential to correctly set up the throttle channel on your radio. The Piccoboard automatically sets the throttle zero point to be the stick position that it sees when it powers up, but the throttle travel is a fixed amount. If your transmitter has insufficient throttle travel, it is possible you will not be able to reach 100% throttle and will have a hard time hovering as the pack runs down. The reverse situation is not good either. If you have too much throttle travel, you can raise the throttle stick past the 100% power point for the main motor. In that case, the main motor of course cannot exceed 100% power, so the additional stick travel has no effect on the main motor power. BUT, the tail motor does not run at 100% power even at full main motor power, so the tail motor CAN continue to increase power past the 100% point for the main motor. As the pack runs down and you continue to raise the throttle stick to compensate, when you pass the main motor 100% point this will cause a right yaw. If you have a computer radio, throttle travel is easy to set.... put the throttle stick at zero with the trim at neutral, turn on the Piccoboard, let it initialize, and then advance the throttle. Observe the motor power. You should reach a point where the motor speed stops increasing JUST BEFORE you reach the top of the throttle stick travel. If the stick reaches the top of its travel and the motor speed has been increasing all the way, you may not be reaching 100% throttle. Use the ATV function on the radio to increase the throttle travel until the speed stops increasing. Go a tick or two past that and you are done. If you do not have a computer radio, your options are limited. You can set the throttle trim to the lowest position while you initialize the Piccoboard, and then raise it for flight. This may give you enough throttle travel. Note that some radios seem to incorporate an internal throttle channel travel stop which can be removed to get more travel. Rudder channel and gyro setup The rudder channel and gyro setup can be confusing, but it isn't all that hard. Like the main ESC, the tail motor ESC accepts whatever throttle position it sees on startup as the zero point. In a perfect world, this would ensure that the main and tail motors started at the same throttle position. However, there are a couple things that can affect that initialization process. If you haven't already, see Rudder trim drift / zero point initialization before proceeding. Once you have the main and tail motors starting at approximately the same throttle stick position, you can proceed to set up the tail motor mix and the gyro gain. The Piccoboard has two adjustments. One is the gryo gain, and it controls how much correction the gyro is allowed to make when it detects a yaw motion. Too much correction and the tail can oscillate back and forth. Heli folks call this "tail wagging". Too little correction and the tail can become very touchy and swing around with the slitghtest disturbance. For the moment, set the gyro gain pot at approximately the 90% CW position. This will be a good starting point, and it is not overly critical. The second adjustment is the mix pot. This pot controls how much tail motor power is applied as the throttle stick is increased. Again, set this pot at approximately the 90% point to begin with. Apply power, let the Piccoboard initialize, and try lifting off. If the heli wants to yaw to the left (nose moves to the left), you need more tail power. Land and turn the mix pot VERY SLIGHTLY clockwise. Conversely, if the heli wants to yaw to the right (nose moves to the right), you need less tail power. Land and turn the mix pot VERY SLIGHTLY counter clockwise. This is a touchy adjustment and it is very easy to go too far. Note that it is not absolutely necessary to power down and power up after making a mix pot adjustment, although the mixer does seem to slightly affect the zero point. However, it is a good idea to make the adjustments with power off in case the Piccoboard decides to go berzerk. It happens! Don't ask.... Lift off again, and re-check. Make adjustments as needed until you can initialize, lift off, and hover with no rudder stick movement needed once in a hover. For an even finer adjustment, temporarily reduce the gyro gain to make it easier to see small mix inaccuracies. Once you have the mix set correctly, move on to the gyro gain. Basically, you want as much gain as you can get without tail wag. The more gain, the more stable the tail will be. However, since this is a simple gyro, if you make it too stable you may end up with a tail that is hard to move. If you like the stability and have a transmitter with adjustable ATV, you can increase the rudder channel ATV to retain the stability but get a more responsive tail. Collective pitch throttle curve setup The following applies to the Ikarus version collective pitch modification but in general is applicable to any collective pitch setup. It isn't really that hard to set up. Set your pitch servo and linkages so that the pitch goes from as much positive as the pitch slider will allow before hitting the hub to "some" amount of negative. The amount of negative is not critical if you do not plan on inverted maneuvers, but you should have some to ensure easy descents in wind. You want the servo travel to be as great as possible (to improve servo resolution) so you will probably want the linkage in the innermost hole. Set the pitch curve to 0, 25, 50, 75, 100. In other words a straight line using all the servo travel. That takes care of pitch. Initially set the throttle curve to something like 0, 50, 80, 90, 100 and power up. If you do not have a reasonable revolution mix yet, hold the heli for the next steps. If you are using the Futaba 8UAFS (or 8UHFS) this applies to you. Not sure about JR. Bring up the throttle curve display, and apply throttle/collective until you are on point #2 (as in 1,2,3,4,5). Adjust the head speed for somewhere between 1500-1800 RPM using an airplane tach or your ear if you have a good ear. Advance the collective to the next point, #3, and do the same.... adjust the throttle curve at point #3 for the same head speed as in the previous step. Repeat for step #4. You should be able to maintin the head speed to point #4, and you will probably run out of throttle by the time you reach the last point. This will get you to the point where you can set the revolution mix and have a relatively constant head speed and try flying. Note that the head speed will be at maximum on a fresh pack and drop slowly as the pack runs down. I have mine set to run 1800 RPM on a fresh healthy pack and it drops to about 1500-1700 RPM for the bulk of the flight. If you fly indoors under flourescent lights, you can verify 1800 RPM as the point where the shadow on the rotor disk seems to be stationary with four blades shown. I have found that with the pitch arms set to the specified 4.5mm I need all the positive pitch that the slider will allow before it hits the hub in order to fly at the end of the pack. If you can stay in the air as the head speed drops past 1300 RPM (REAL slow in CP Piccolo terms) you have enough pitch. Another test is to try a full collective climbout on a fresh pack... it should be abrupt and fast with some head speed sag OK. Piccoboard Heading Hold module setup Unfortunately the HH module instructions from Ikarus are a bit sketchy and completely ignore a very important point..... the trim for the HH function is totally independent from the auto zero function of the tail ESC. I suspect many people who think that the HH module does not work simply never had it set right. The several that I have tried seem to work just fine. Here's the correct way to set it up: 1. Set the rudder trim to center. 2. Initialize the board. 3. Advance the throttle until the board enters HH mode. You can tell if it is HH mode because the tail motor will not resume its previous speed as soon as tail motion ceases. 4. While in HH mode and with the heli stationary, adjust the rudder trim until the tail motor speed remains constant with zero tail motion. At this point, the tail motor will speed up when you move the nose left and slow down when you move the nose right but will stay at whatever power level it was at when the motion ceases. 5. Do NOT change the rudder trim for subsequent flights. As soon as you power down and re-initialize, the Piccoboard will accept the new trim position as zero. Since the rudder trim position is now correct for HH mode, the tail motor will start and react normally at very low throttle settings and when you enter HH mode the trim will be near perfect as well. You can fine tune the rudder trim in flight for zero residual yaw. Once set, leave it there until it is necessary to change it again in flight. Do not worry about the fact that the tail motor may continue running at zero throttle after changing the rudder trim. Each time you initialize, the Piccoboard will reset the non-HH zero point for you to the current trim position. As long as you have not changed it between flights, it will then be correct for both modes. Trim Especially for the first flights, proper trim and balance are absolutely essential. The Piccolo is very light, and can move surprisingly fast if it wants to.... and it DOES want to if it is not in trim and gets away from you. Here is my routine for trim. Also see below for balance. 1. Set the servos and subtrims (if available) so that the servo arms are horizontal with the transmitter trim tabs at neutral. 2. Adjust the flybar arms so that the ball sockets are even with the flybar rod and adjust the flybar paddles so that they are exactly horizontal. 3. Adjust (bend) the servo links so that the swashplate is horizontal in both pitch and roll axes with the servos neutral and the flybar link ball sockets even with the flybar rod. 4. The above several steps are somewhat interacting.... go over them a couple times. 5. Rotate the main rotor through the full 360 degrees and verify that the flybar paddles remain EXACTLY horizontal (ie., zero pitch) all the way around. If they do not, and if you have the stock swashplate setup (ie, not a ball mod), adjust the flybar arm closest to you to level the paddle closest to you. Then turn the rotor 180 degrees and repeat for the flybar arm and paddle closest to you. After several iterations, you should be there. Re-check in all orientations. 6. At this point you should be very close. Gently hold the tail boom just behind the attachment point (so that it is free in the roll axis) and slowly apply power. When you get to hover power, adjust the trim so that it there is no roll tendency. This should be a very small or unnecessary adjustment if you have done the above carefully (especially the 360 degree flybar paddle zero pitch part). 7. Holding by the skids and the tail boom, apply enough power to support the heli and briefly loosen your grip to see if there is any yaw tendency. If so, power down and adjust the mixing pot and re-try. 8. Leave the gyro pot at the factory recommended setting (90%?) for now. 9. You should be very close to perfect trim at this point, after balancing (see below). Balance Balance is the other critical portion of preparing the Piccolo for its first flights. With my sliding battery pack, I can easily set the balance as desired.... I set it for neutral or very slightly nose heavy by moving the battery pack to suit, as follows: Position the rotor blades perpendicular to the tail boom and hold the heli by the blade attachment bolts and adjust the battery position so that the heli is level. I determine level by adjusting so that the skids leave the ground level. It's easier than trying to eyeball the heli frame, since the tail boom slants upwards. Tracking Tracking refers to the path of the individual blades in flight. They should both be exactly in line with each other when viewed from the edge of the rotor disk. If they are not, you are wasting some power and the heli may not fly as well as it could either. This turned out to be a rather lengthy topic... don't be intimidated. It isn't as hard to set up as it might look. It just takes care and patience the first time around. An out of track condition indicates that the two blades are not producing exactly the same lift. This could be due to the two blades not having exactly the same shape (very possible if you are using cut blades) or not having the same pitch. If you are flying cut blades, remove them and lay them one on top of the other and check very carefully to see if the two blades have EXACTLY the same shape and profile. If your cut was not accurate, one blade could be slightly different in width (chord) and therefore produce more or less lift that the other. To correct this, securely tape the two blades together at the leading edge and with a bolt through the bolt hole. Make sure that the leading edges are EXACTLY even with each other. Now, using a sanding block or a flat table surface, sand the trailing edges together until they are EXACTLY in line with each other. With the blades still removed, check the flybar and linkages. The flybar itself must be perfectly centered on the head, and the paddles must be perfectly centered on the flybar.... in other words, there should be an equal distance from the exact center of the head to each end of the flybar, and to the end of each paddle. This step is necessary for static balance. Now, before proceeding any farther, make sure that the flybar arm ball joints are TOTALLY free. The flybar should be hard to keep balanced level, and the slightest breath of air should tip the flybar all the way to one side or the other.... there should be no noticeable difference in friction between linkages connected and linkages disconnected. This is a VERY IMPORTANT step, because stiff joints will mask small static blade position errors and cause tracking errors that will change from flight to flight. Finally, put a small piece of brightly colored tape on the leading edge of one blade so that you can visually identify the blade in flight when viewed edge on. Now, you are ready to proceed with tracking adjustments! First, see topic "Trim" and make very sure that the flybar paddles are absolutely level with the head in ALL orientations. This is a sensitive adjustment, and small differences WILL affect your tracking. Set the blade static position..... set the blades by eye to 90 degrees to the flybar. This initial setting is not overly critical. Now adjust the position of one of the blades until the flybar will balance level and you have the two blades set perfectly. Remember, though, that this step will NOT work unless the flybar links are totally free. At this point, I would tighten the blade bolts so that the blades will not shift in flight... they do not need to if you did this step carefully. If you are still using the nylon bolts supplied with the kit, see "Main rotor blade attachment modification". I do NOT advocate running the blade bolts loose, because unless they are at exactly the same tension, one blade will be more free to shift than the other and this will eventually cause the blades to end up in the wrong positions, with cooresponding negative impact on balance and tracking. Apply power and as the speed increases, observe the rotor disk from the side. If you did everything carefully and correctly, the tracking should be very close. You can now make small adjustments by identifying the high blade and VERY SLIGHTLY rotating the flybar so that the paddle ahead of the high blade has less pitch. If it takes more than a very small adjustment, then and only then should you consider changing the individual blade pitches with tape or screw adjusters. Rudder trim drift / zero point initialization Each time I power up for flight, I raise the throttle a bit and make sure that the tail rotor begins to turn at the same time as the main rotor.... if it does not, I power down and try again (see explanation, below). This way, the rudder trim is always very close (assuming the Piccoboard mixer is set right) and I don't get a big surprise in the air. Note that the Piccoboard takes the throttle and rudder positions it sees at power up as the zero points. For this reason, you must power up the Piccolo with the throttle stick at zero and the rudder somewhere near center trim. This can also be affected by a stiff tail motor. See the section above on the tail motor. For a long time, I had been puzzled by the fact that sometimes the rudder trim was perfect and sometimes I had to move it many clicks to get it right after initialization. By experimentation, I have discovered that the rudder speed control zero point (or maybe the gyro??) can be offset during initialization if the transmitter is too close to the Piccoboard. There seems to be a direct connection between initializing with the transmitter within a foot or less of the Piccoboard and having the rudder trim offset enough to affect flight. Repairs Ah, this will be an important topic, eh? I have LOTS of experience!!! When I first got my Piccolo, parts were very hard to find and out of necessity, I got pretty good at repairs. Nowadays, parts are easy to find from places such as Dream Hobbies. However, if you are away from home, it is always good to know how to repair things in a pinch. Fortunately, the plastic used by Ikarus can be repaired with regular CA, and is almost as strong as before the break. Flybar paddles usually break where the paddle attached to the flybar shaft. I use thick CA and a bit of care, and re-use broken flybar paddles many times before I decide to replace them. They usually get replaced when they end up crooked after a repair. The tail rotor can be repaired with CA, but the joint is stronger when re-inforced with a bit of CF mat and thin CA. It ends up a bit out of balance, but not enough to seriously affect anything. The tail boom is easier to break than I expected. Mine split lengthwise over several crashes, and it became easier and easier to rotate it. I dribbled some thin CA into the visible cracks, and that held for a while. Then I had a sloppy landing and had a boom strike as the rotor disconnected. The resulting "crack" was quite audible! I found the boom had been broken almost in half, but the two halves were still attached. I used CA to make a temporary fix, and then wrapped some CF tow around the break and wicked in some more CA. It seems to be stronger than before the break. OOPS! Broke it again, and this time it was too badly damaged to repair. So I cut it off close to the main frame and the tail rotor assembly. Then, I used an undersized drill and drilled out as much of the remains as possible. At that point, I used a small screwdriver and X-acto knife to pick out the rest of the pieces. CA'ing in is a BAD idea! But after I had the sockets cleaned out, a replacement slides in nicely. HOWEVER, I had a piece of CF tubing that I bought at the local hobby shop that was about 0.003" larger OD than the Ikarus boom, and it slides in with a nice tight friction fit and holds well. So although I have ordered a couple replacement Ikarus booms, I am using a boom that I made from the oversized stuff, and it flies fine. It has to be heavier because it has thicker walls. But it balances the same and flies identically. The landing skid attachment points are relatively vulnerable, and I have broken them off several times. I re-attach them with CA, and after it hardens, I wrap some CF tow over and around the joint. The result is almost as strong as the original, and since the skids and the CF are both black, the repair is not very visible. The canopy can be repaired with transparent tape from the inside. The original plastic rotor hub can sometimes be repaired, but I do not recommend it. I never found a way to make it as strong as the original, and a failure at "altitude" could be detrimental to the heli. This is a part that when broken should be replaced either with another original, or with an aftermarket version. The swashplate balls, believe it or not, can actually be CA'd back on if you are very careful. I did it many times before I caught on that if the links are very loose where they attach to the flybar arms, they will disconnect before they rip a ball off. I finally replaced the swashplate and haven't broken a ball off yet. The swashplate anti-rotation pin is easily broken off. I CA'd a piece of music wire in it's place and wrapped a bit of CF around the joint. Stronger than the original! Ah, but when the next crash broke the stub off flush with the swash, I realized that strength is NOT a virtue here. The best way to repair the anti-rotation pin is to CA a piece of music wire tot he underside of the stub and NOT re-inforce it with anything. IT will hold just fine, but in the next big crash will break free without harming the stub. It can then be easily re-attached. Carrying case The cardboard box the Piccolo comes in makes a very nice carrying case after the heli is assembled. It is just the right size for the heli lying on its side if the rotor blades are folded together and the tail rotor is positioned vertically. I added a couple styrofoam inserts to hold the chopper securely in any orientation. See photo. I also use the plastic box the Piccoboard came in for spare parts, and have this velcro'd in the case as well. |
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