Getting the best 3D performance out of your helicopter
Everyone that flies 3D wants the best performance out of their heli, you always want to have it in good working order, flying nice and never needing maintenance at the field, just put fuel in and fly. Sure we will all have a little problem here and there that we can’t help such as a broken muffler or other unforeseen defects.
For the most part you want people to know that your care about your equipment, that you know what your are doing, and that your heli is always working with no problems. For example lets say that you are asked to do a demo flight for a couple of spectators. They have all heard that you are a good 3D pilot, so you go out to your starting position with confidence knowing that you will impress the people watching you. After you lift off you notice that your mixture is a little rich so you tweak the needle in two clicks, no big deal. After your up for a bit you notice that something doesn’t feel right, its not up to its usual flying standards. After you land the crowd gives a somewhat enthusiastic applause, you approach one of the spectators and they say to you,”that was pretty good but I’ve seen you do way better”. You reply with a “I accidently ruined my set up last night when going through my radio”. Now think for a second, you are a competent pilot and you have just told someone that you do not know what you are doing when it comes to you radio. Your heli was not flying to the best of its abilities, so for the rest of the day you fiddle with your set up until you are almost satisfied but you not quite, the day is suddenly over and you head home with the less than perfect set-up you have managed. You later realize that last night you were trying to improve your set up and accidently set your ATV’s to 50% and your throttle curve is way off because you didn’t know your radio. I will try to help you to prevent a similar situation from ever happening by giving you some tips and pointers on how to get the best performance out of your helicopter.
First look at what you can do to your machine mechanically to enhance its flying characteristics. There is a lot you can do mechanically to help your machine fly better, but a few things like blade tracking and engine tuning seem to be the obvious. If you are like me and run a lower rpm on your normal curve than idle up, you may possibly be tracking your blades in the normal curve or flight mode. I recommend that you track your blades in idle up because tracking errors tend to increase with large rpm changes. For myself on normal curve at 1400 rpm my blades are out of track a very little bit, but in idle up running 2000 RPM they track perfect. Here I made a compromise so that my helicopter flies very smooth in idle up and is a bit out of track in normal mode resulting in small shakes during a very fast abrupt flare, which I don’t normally do because of this. So whichever mode you fly in the most, track your blades when in that mode. You should also have a good all-round linkage set up so that when at full collective/cylcic travel nothing will bind. If binding does occur then pull the swash plate down by adjusting your linkages, or you can leave it how it is and lower your ATV values for roll and fore/aft leaving you with a less sensitive, agile machine. Another thing you should always do mechanically is to keep all of the screws tight that are into plastic and apply lock-tite where needed such as engine mount screws, metal to metal set-screws, clutch to fan etc. Dial indicating the clutch is also a good idea from “experience” I know that if you do not carry through with this procedure your clutch may last a very short time. (Longevity average is about one-two weeks) if you do not have a dial indicator then I suggest that you get one or borrow one from someone that does. Check for good engine alignment. To do this, bolt the engine loosely to the side frames and turn the start shaft with your fingers until you are satisfied with the smoothness, then sight the clutch bell and fan hub to make sure they are parallel in both axis after you are satisfied apply lock-tight to all of the bolts into the engine mount and tighten them. After the engine is in and running good then mount a header tank where ever you can find free space on your heli. You will really notice a difference in engine performance because now the engine is always sucking fuel not air. You will notice that when you tip you helicopter straight down with half a tank of fuel the clunk is picking up air only. With the header tank in place when the main tank is sucking air in a strange 3D maneuver the engine will not quit because now its sucking fuel from the header tank.
Now lets move on to some electrical additions such as servos and/or gyro adjustments. Servos on your collective and cylcic do not matter much for the smaller machines, For several years I flew Futaba ball bearinged 148’s for all my controls on my Raptor. With the bigger 60 sized machines you may want to get a little better servo as they have to move a much bigger disk. If you are using eCCPM mixing then it is a must to have all 3 cylcic/collective servos the same speed thus creating a smooth, easy to control system. In this case you’ll need to spend a bit more on servos as speed may vary with lower grade of servos. If you have one servo faster or slower than the others un-wanted roll or fore/aft input will be fed into your control system during collective moments. It is also mandatory for 3D flight to get the best performance out of your tail rotor as possible. First I recommend a good servo such as the Futaba, JR or Hitec line of high speed digital servos, now remember were trying to get the best out of our helicopter, if you will settle for 10%-20% less gyro gain then use a lesser servo. Most important, invest in a heading hold gyro, this will really improve the flying characteristics of your model by giving you the option of easy backwards flight. Any heading hold gyro will do this but personally I like the CSM 540 because of setup ease and the way it locks the tail in place during aggressive 3D maneuvers. When setting the gain for you gyro start at the percentage that the manual recommends, try some FFF, if the tail shows no sign of wagging then bring your gain up 5% and keep doing so until your tail starts to wag at this point bring the gain down 5% and leave it at that. If the factory settings seem to be too high you tail will wag immediately slow the helicopter down, land it and decrease the gain by 5% at a time until the wagging goes away. Little things like cutting out you vertical tail fin for 3D will help you fly sideways without pulling the engine down as much and may increase your gyro gain 5% because of less area and drag.
For flying backwards it is also nice to have a canopy that is very profile and that wraps around the frames near the back so that it is stream-line, as I said it is nice to have one but is not the best investment you will make to get the best 3D performance out of your heli. If your canopy is open in the back when doing backwards flight then it will act as a parachute slowing the helicopter down.
It is very important to accomplish a good 3D set-up with a basic pitch curve of +10 degrees at full collective 0 at half and -10 at bottom. Available power will decide how the +/-10 degrees will be altered. If you find your helicopter too sensitive but like the roll and flip rate the you can put in some cyclic exponential to make it feel softer in a hover and foward flight. You might want to look at the cyclic pitch too. This is easiest to measure at zero collective with a level swashplate and flybar fixed or held in the level position. The blades should be exactly over the nose and tail, for the roll cyclic and exactly over the port and starboard for the fore/aft cyclic. Look for +/- 6-7 degrees on the pitch gage. Eg: full left cyclic indicates -6 degrees on the blade over the nose and +6 degrees on the same blade with full right cyclic. Remember the rotor disk takes 1/4 revolution to respond the point of maximum cyclic blade pitch change. If you have just recently been introduced to 3D flying then it is best that you read over your radio manual until you are 100% positive what you are doing 100% of the time. After you have read over your manual create a new model in your radio and call it experiment. Copy your heli into the model called experiment and fool around a bit with pitch curves, throttle curves and ATV’s for 3D until you are happy with the setup you have accomplished. Just remember if you ever make a mistake and don’t know how to fix it you can always start over because you still have the un-touched original model.
It is essential that you pick the right main rotor blade, tail rotor blade, paddle and head dampening for your flying style, for a 3D setup you will want a fast reacting, agile helicopter so we will go with a light blade. But most 3D pilots end their flight with an auto and an auto requires heavier a blade for more inertia. Now your stuck deciding between the two, do I want a good autorotating machine or an aerobatic machine? Well you can have both, if you go with a light paddle and a heavy blade. You can get the best of both worlds….sometimes, if you don’t get the right paddle shape the lightness can result in pitchiness during fast forward flight. It’s up to you to experiment with this. Now a days most models come with a best standard combination so it might or might not be up to personal standards. Different people all like different head dampening, personally I like a softer head dampening system as it gives you a nice soft but aggressive 3D feel and if you make a mistake when flying it is less noticeable and more forgiving. A tough or harder head dampening will give you a more rugged feel and when you do make a mistake it will be more noticeable. Tail rotor blades can help to enhance your tail rotor. If you notice that your tail is weak after a flight count how many times the tail rotor spins for every revolution the main rotor spins. If it is under four turns then try some longer tail rotor blades, if this doesn’t work try a wider chord and keep experimenting. Remember all of this is to suit your flying style so it’s up to you to find the right combination for taste.
If you are flying 3D it is important to pick out the right heli. Almost all helicopters are fine for 3D flying but there are some leading manufacturers such as Thunder Tiger, JR and Miniature Aircraft which are the most popular, even though there are so many other helicopters to choose from. If you want the best power to weight ratio then I suggest you get a 60-90 sized heli. There comes an extra price to pay when you get into this size, fuel is the biggest thing if you don’t crash often. If you fly every weekend with a 90 sized machine then in one summer you could easily burn ten cases. This is why we like to stick with the 30 sized, they might not have quite as much power but they will still do almost as good 3D. The correct engine is almost as important as the heli. I think that most any heli engine out there is good but some put out more power then others, some are harder to break in and I’ve only seen one bad engine , but then a year later a newcomer came to the field with an identical engine working great. So it’s up to you to choose.
No matter what heli, engine and/or radio you choose it is always possible to accomplish an exceptional set-up. Sometimes a cheap radio will stop you from getting the exact set-up you want but for 700 dollars you should be able to get a radio you will be very happy with. I hope now that you have read this you can go out to the field and find the set-up that suits you best. If you do not get the best setup you want then ask for some help from a club member who knows what he is doing.