Frequently Asked Questions
2. Crash/Repair related questions
3. Building related questions
4. Beginner questions
5. Battery questions
6. Radio questions
Glossary of terms
|Performance related questions|
|Gets more oil then normal after a flight||1. The muffler could be leaking where it
joins the engine. If you use a gasket, take it out. I (tighten
the two bolts)
2. If using the stock muffler, then it's leaking where the two halfs join (tighten the long bolt that goes through the center).
3. The stock muffler could have a crack in it near the engine bolts.
|Fuel appears to be leaking from the head, but the glow plug and the head bolts are tight.||1. It is from the carb. At idle, it tends to spit fuel out into the fan shroud and down onto the head of the engine. This is just a characteristic of this carb and has not caused me any problems.|
|Hear clicking sound or see tail blades momentarily stop during spool up.||1. The tail belt is too loose. You should
adjust it so that you can push the belt inward by an 1/8"
on both sides.
2. The belt has a stretched spot from a previous crash or manufacturer defect.
3. After a crash you put the belt on upside down. A new belt does not have a direction, but over time the teeth form in a way that when installed upside down it tries to catch the side of the teeth in the main gear instead of meshing in the center.
|Hear strange noise, tail is not responsive and engine does not have as much power as it should.||You have the belt twisted too much. It is only supposed to have a 1/4 turn counter-clockwise. If you have a 1/2 or 3/4 turn the the teeth of the belt will hit each other inside the tailboom.|
|Want more power from the engine:||R30:
Try a Hatori cnh333 for the pipe and cnh341 for the
header, also the Helimax pipe has good power too. However
keep in mind pipes are usually more picky on engine
adjustments. A good muffler to use that has some power
characteristics of a pipe is the Weston Genesis. Note
that there are two version, one if you run low nitro and
the other if you run 30%.
R50: The Hatori SB-15FH or the version Jason Krause makes have good power and are not very loud. The Curtis Muscle Pipe 2 has good power but personally I do not like the sound.
|Engine not running right||Engine Tuning How-to|
|How do I check the glow plug?||Checking a glow plug|
|The muffler is too loud||Get a Hatori SB-8, it really sounds great! Other options are Weston Genesis Pro pipe and the KSJ speed 30 tuned muffler|
|Radio Glitches||The common cause is notchy top and bottom
main shaft bearings.
Another possibility is that if your struts have worn through on the bottom like mine, then the skids might be loose enough to vibrate against the set screws.
Also the screws that screw the tail boom support rods to the horizontal fin are just a little long. Use a dremel cut-off wheel to take off the last 1/16"-1/8" from the screw. This will keep it from making metal to metal contact with the tail boom.
Visit my RF troubleshooting page
|Horizontal Fin Vibrates||This is a tail balance problem. You could have an off balanced tail rotor blades, bent tail rotor shaft, bent or cracked blade grip, bent pitch arm on slider, worn/loose belt, or a worn output or input shaft pulley.|
|Tail boom support rod cracks right behind screw hole||R30:
This is due to vibration. The question is where. The two
most probable causes are an off balance tail rotor (see
fix in the above row) or vibration from the engine area.
I have heard others who had this problem say they checked
the balance of everything and still have the problem. I
never had this rod crack until I had a clutch failure.
This makes me think that when one clutch shoe engages
just before the other, this causes a serious out of
balance problem for that moment. This repeated action
eventually brakes the support rod.
R50: If you converted your 30 to a 50 then you have the crimped end type support rods. These do not seem to stand up well to the torque of the 50. If yours broke then order the 50 support rods, they are like the ones that come with the Raptor 60, but cut down to the right length. Really just about any 30 size support rods will work, I have not tried these, but a tip from Jeff Blunt said the Sceadu 30 support rods are good to use. Also there are many carbon fiber upgrade support rods available.
|Notice white powder around fuel tanks||R30/50: Sand the inside edges of the frame where it comes in contact with the tank. You can also put tape on the inside of the frames to help keep the tank from vibrating around.|
|How do I break in my engines?||The way I have always done it is to actively adjust my engines during break-in. During this time the engine can change several times so as soon at it does I land and adjust it. To begin with, on the first tank I first get it so rich that it hovers a little above middle stick. Hover for a couple minutes then let it idle for a minute to cool down. Do this for a whole tank. Let the engine cool, then on the 2nd tank you can hover and move around (at a slow walking pace). Do some of this for a few minutes and let it idle for a minute, then do some more. On the 3rd and 4th, just do low ground maneuvers like figure 8's, outside circles, and other things that don't stress the engine. Each tank you can start advancing a little more. At all times, watch for changes in the rotor/engine rpm. If it increases then richen the engine, if it decreases then lean it. Note: If you let it go too long with a lean condition then the rpm will drop in which case leaning would not be the correct thing. Just keep a close ear out for engine rpm changes and take care of the problem right then.|
|The tail turns about 20 degrees anticlockwise when I give full throttle in a climb||R50: The 50 size engines have a lot of torque. If the tail blades were longer or the tail gearing spun the tail blades faster then that would compensate. However you can't use longer tail blades because it would hit the main blades. And a different gearing is not available. So try some tail blades with a wide chord and stiff, like the NHP 85mm tail blades that I use. Another thing would be to decrease the top end pitch. The only problem with that is it also decreases your climbout rate. In normal mode that's not a problem for me. Another thing to help the tail is to run a higher rpm. In flight mode 1 I run about 1850. With this speed I do not see the tail move out of place. Also a tuning problem with the engine will cause this. If there is a big difference between the low speed side and the high speed side then you will notice a giant increase in engine rpm as the carb passes from one side to the other. This sudden torque is what causes the tail to turn. Suspect a bad glow plug or bad clunk line in the tank.|
|Crash/Repair related questions|
|Parts to check other than the usual||Check double link on the head for cracks
The tail hub can get warped and cause the tail blades not to track
The top and bottom main shaft bearings can be damaged. They will have a notchy feel and if left in, can cause RF glitchs.
I found the auto hub bolt was broke in 3 places on a friend on mines Raptor.
|How to check spindle shaft||Remove one main blade, leaving the other on,
stick your socket on the
bolt and rotate the spindle. The remaining blade's tip will travel up and down if the spindle is bent.
|How do I get the bearings out of the engine||First take everything off the engine, carb/piston/sleeve/etc. It should be stripped down to just the engine case and front and rear bearings. No gaskets/o-rings. If you can remove it, then do. Put the engine case with bearings in the kitchen oven and heat at 350F for 15 minutes. Next hold the engine with an oven mit or thick cloth and tap the back of the case on a block of wood. I have done this many times and at most I have only had to hit it twice for the bearing to fall completely out. You will have to tap the front bearing out with some type of shaft (NOT the crankshaft) poked through the rear of the case. It will come out easy while the case is still hot. To install the new bearings, re-heat the case and the bearings should slip in. I usually install the rear bearing first. This is because I put the bearing on the crankshaft and use the crankshaft to help me align the bearing straight.|
|How to prevent the front of the frame from cracking in a crash||I have not tried these suggestions:
1. Take the two screws that hold the front landing gear strut to the frame and replace the screws with zip ties.
2. Replace the two screws that hold the front landing gear strut to the frame, with 4-40 nylon screws (if the frame is new then tap it first with a 4-40 tap). I haven't broken the landing struts since I started using nylon screws. Make sure you use 3/4" screws so you can unscrew the studs after they break.
on tail split
|Do not tighten the tail pitch slider too
tight on the brass sleeve as this eventually causes the
sleeve to split in half at the end of the threads leading
to an ultra rapid pirouette :)
Tip provided by Colin Smith
|One tail rotor blade came off while spooling up or flying||Regularly check the set screw (pg. 12, step 13, item 5) by feeling if the tail blade grips have slop. Both of my ARF Raptor 30's came with red loctite on these screws and they have never loosened on me. The only other reason for this screw to come loose or break, would be a result of a previous crash. So if the tail impacted the ground hard, you should examine the set screws to see if they got bent. Also check the hub by spinning the tail rotor and watching to see if the tail blades track the same. If not, then if the set screws are good, that means the hub got bent. And of course check for a bent tail rotor shaft, running a bent one would cause vibrations that I'm guessing might cause the set screws to come loose.|
|Is there a redesigned t/r hub||Some people have replaced the stock tail rotor hub with the one piece design JR JRP960222 Ergo t/r hub instead. It's steel with a built-in threaded studs. Make sure to shim out the little attachment point for the pitch control arm (on the grip) by 1/16" to minimize any twist/preload. Pictures courtesy of Mark McAlpine.|
|What to do about a stripped muffler bolt hole||When the threads strip in the muffler, get a bolt long enough to extend out of the muffler flange so that you can put a nyloc nut on it.|
|Get the tail on right!!!||Click <here>|
|How do I figure out if the gyro needs to be reversed?||To figure out the right gyro direction just watch for the control rod as you rotate the helicopter so the nose goes to the left. If the control rod gets pulled forward then you have it correct. This is assuming you have the tail assembly correct I have helped many with the tail backwards. Basically what you are looking for is for the control rod to go the same direction as when you move the rudder stick right. If it's not going the right direction then flip the reverse switch on the gyro and turn the power off then back on for the new setting to take effect.|
|Metal ball keeps wearing out but the link is still good||This happens because dirt gets embedded in the plastic of the link. This then acts like sandpaper on the metal ball. So you need to replace the link along with the ball.|
|Building related questions|
|Clutch installation||The best clutch clearance should between .006 to .010 inch on each side (this is measured between the liner and the round part of the steel clutch that does not swing out). When gluing the liner in the clutch bell, I use JB Weld because it has a thicker consistency. I put two layers of electrical tape on the clutch then put the clutch in the clutch bell and let the glue dry. The two layers of tape should provide the correct clearance. Mine came out 0.01 on each side. Before you re-install the clutch, be sure you do the Clutch Fix|
|Clutch Bell Removal|
|Why does the clutch fail?||Clutch Repair|
|How do I know if I have the new type tail pitch fork?||The new one has an extra support molded in. It goes from the arm to the hub. Here is a <picture>|
|How do I 'goop' the Hitec servos||Note(8-2002): I have heard that the Hitec 525
and 545 don't have a problem with needing the motor wire
gooped anymore. Still it wouldn't hurt check.
Take the four screws out of the case, hold the top or it will come loose from the main body. Lift the circuit board out and use an electronic grade flexible glue to secure the wires. I have heard Goop will chemically attack the wires, but I used it and so did some of my friends. So far we have not had a problem. Use this at your own risk or shop around for some so-called electronics grade goop. One that I have not tried, but was told it would work best is made by Tamiya Plastic Model Co. Number is in Japanise(628). But it's called Liquid TheadLock TP-4. Whatever you decide to use, put the glue around the wires that go into the circuit board. Also goop the wires on the other side of the board. Notice how they did not goop these wires, with vibration they might break right at the surface of the PCB. Also good the motor wires. Mine had glue on them, but I put a little extra just for safety.
on tail split
|Do not tighten the tail pitch slider too
tight on the brass sleeve as this eventually causes the
sleeve to split in half at the end of the threads leading
to an ultra rapid pirouette :)
Tip provided by Colin Smith
best position to start with for tail centering is to
adjust the rudder link so that you have 4.5mm between the
pitch slider and the tail rotor casing with the
collective stick centered up/down and left/right.
NOTE: Here is a great tip that Lenny Nimmerrichter sent me. Instead of measuring the 4.5mm gap on the tail to center it, just align the tail control lever so that it is parallel with the tail shaft.
|Just put the tail together but the shaft can be moved about 1/4"||The tail pulley is assembled wrong. It is a 2-piece unit. The end flange is pressed into the pulley. The flange has a long and short shoulder. The short shoulder is supposed to be assembled toward the pulley. If the long shoulder was pressed into the pulley, this would leave the short shoulder out which allows for the free play.|
|Which way do the thrust bearings go in the rotor head?||Yes the thrust bearing races are close to the same size. The easiest way to tell which one has the larger inside diameter is to place them on the spindle shaft and rock them back and forth. The one that moves the most is the one that needs to go toward the center of the rotor. The other one with the smaller inside diameter goes toward the blade.|
|Where can I get a heavier clunk?||If you replace the clunk fuel line with thicker/stiff fuel tubing and you plan on doing 3D, then you might need a heavier clunk like the KSJ 537.|
|How do I align the flybar paddles?||<Here> is a page I wrote to help solve problems associated with the flybar.|
|After building my tail rotor, there is a lot of slop in the grips.||The problem is that the blade grip halves are
not molded cleanly where they meet. You can flat sand the
halves smooth and by trial and error, remove enough from
the half without the pitch arm to make a tight fit over
the twin bearings.
Tip contributed by Bill Guethler
|What am I supposed to balance and how?||Go to the <Balancing page>|
|How do I get the receiver antenna wire to go through the protective tube?||First straighten the wire as much as you can. You don't want any kinks. Next squirt rubbing alcohol in the tube and on the wire. Start pushing the wire through the tube while you continue to put alcohol on it.|
|Get the tail on right!!!||Click <here>|
|When installing the fan, do I put the washer under it?||No, the bottom of the fan hub has a raised area to rest on the inner race of the front engine bearing and does not require the washer. Plus the wash causes the clutch to be that much higher. Ideally the bottom edge of the clutch should be at the bottom edge of the clutch liner.|
|Do I use a gasket between the muffler and engine?||No. I have found the gasket is just a source of problems later. They always seem to get a whole in it which causes an air leak and resulting engine adjustment problems. I just clean the surface of the exhaust flanges and as long as they are flat then it should not leak. None of mine have. Another alternative that I have not tried is to use epoxy as a gasket material. I have heard this works, but I like to keep things simple so I just bolt the muffler straight on and will continue using this technique. BTW: You need to re-tighten the muffler after the first flight while the engine/muffler are still hot. This will keep the bolts from coming loose.|
|What are the settings for my radio?||I would not be able to give exact values as
there are many differences even between identical setups.
Besides it is best to do the setups individually to give
the most optimal settings. I can however give some pitch
setting to go with for learning to hover. I have setup a
lot of helicopters and for those just starting out I
always setup 0 degrees blade pitch for bottom stick
position, 5 degrees for the middle stick position, and 9
degrees for the top. You do not need any negative until
you start flying around in forward flight. Zero will keep
you from banging the helicopter hard on the ground and
also with only 9 degrees travel from bottom of stick to
top that means the collective will also be much less
touchy then say a 3D setting. Now I do recommend doing
the 3D setup but after setup use the pitch curve to set
the blades for 0,5,9. Info on the 3D setup is <here>
As for throttle curve I always use all 5 points and set the middle three to 10% increments such as 40,50,60. The top point will be 100% and the bottom point will depend on if the radio has a throttle cut feature that is active. If it does then set the bottom throttle curve point to 20%, if not then set to 0%. ex. 20,40,50,60,100
I recommend you read my pages: Radio Setup Overview and Radio Setup.
|What brand helicopter should I buy?||Most of the helis on the market today are all good. With any helicopter the good experience you have is almost entirely proportional to how well the helicopter is built and setup. That is why it is so important for people starting out to get help from someone that understands how to best set one up for the flight level you are at. I see this all the time, but just as an example we will use the one from last weekend. It was a JR Venture and it was in need of a little help. The guy was having problems with the helicopter not lifting off the ground. This heli has eCCPM and I found that two of the servos were hooked up in the wrong positions. After getting this straight (it was causing the top end pitch to unexpectedly change) then I did my normal setup for throttle curve and pitch curve. I flew it and got the blades in track then set the tail to feel nice. After a half of tank of adjusting I handed the controls to guy and after he flew one circuit he kept saying this helicopter has never flown like that before :) That did make me feel good and is the reason I help others :) Anyway the point is no matter what helicopter it is, how well they fly is dependent more on how well they are assembled and setup. For me the determining differences between one helicopter versus the other are in how easy they are to work on, how easy it is to get parts, price of parts, and price of kit. And if you have other heli pilots in your area that you plan on getting help from then you should get something they have experience with. Talk to them about the helicopter you are looking at to purchase and make sure they can help you with it.|
|When can I fly without the training sticks||The general qualification is if on the first tank of the day you can come to a stable hover and sit the heli down straight without letting it slide one way or the other. One thing you will notice is that you use the sticks for orientation more then you would think you do. Also you will have to concentrate more on the landings. With the sticks you can sit it down even if the heli is still moving, but without the skids you can't have any side to side movement. Take them off if you feel comfortable enough to try it, otherwise don't worry about it, no one will punish you for leaving them on :)|
|The tail blades are too close to the ground, is there a mod to fix this?||I know when you are learning to hover you sometimes use the tail to dig holes in the ground <grin>. Some people turn the skids around backwards to angle the back end up a little but the downside to this is that it puts the antenna tube guide on the side of the exhaust. An alternative is to place a thick washer between the back of the frames and skids.|
|What is the difference between 15% and 30% fuel?||The percentage represents the amount of nitromethane in the jug of fuel. In the U.S. 15% is the common amount to use. Other countries typically run 0 to 5%. The 30% gives more power, but until you start 3D you won't need that. In fact a heli that is properly setup and engine tuned will do 3D just fine on 15%. Also one with 0 to 5% will do fine if you run a tuned pipe and the carb is setup to have a fine degree of adjustment. The higher nitro fuels keep their settings better from day to day as the weather changes.|
|When adjusting the blade tracking, which blade do I adjust||Use the blade that you did not use to set the pitch with. If you did not use a pitch gauge or do not remember which blade it was, then it depends on how you want to affect the head speed. If you want more head speed, lower the high blade, if you want less head speed, raise the low blade. If you want to maintain the head speed, you have to raise the low blade and lower the high blade by the same amount.|
|How tight should the blades be||If you have them too loose, then the next time you sit the heli down a little hard, the blade could pivot far enough to chop the tail boom off, I know cause this is what caused my very first crash. Hold the heli on its side with the blades parallel to the ground, a slight bump should not let the blades pivot, if it does tighten them. Don't get them so tight that they won't pivot. The rotor system does need to lead/lag during its rotation.|
|What are pitch / throttle curves, there are no curves in my radio?||A helicopter radio allows you to setup a
pitch and throttle curve. A good radio will have 5 points
of adjustment. These points represent five positions of
the stick, bottom, 1/4, 1/2, 3/4, and top. For each of
these stick positions you can set a value. This value
ranges from 0% to 100% and for the throttle represents
the percentage the carb is open. For the pitch, 0%
represents the minimum pitch and 100% is the maximum
pitch. The radio lets you set two or more sets of curves
for the throttle and pitch. They are selected by flipping
the flight mode and throttle hold switches.
The term 'curve' just refers to the shape of the servo output line if you plotted it on a graph... okay I know that's confusing. Only a few of the high end radios actually display a graph showing the curves. Most radios, including both of mine, only show you five numbers for throttle and pitch settings. These numbers can be used to draw a graph. For example, take a throttle setting of 100,78,63,78,100 (this would be a typical idle up throttle curve). If you were to draw a graph and plot the numbers, then connect the dots, they would produce a curve like the one shown in the chart to the right. That's where the term 'curve' comes from. Click on it to see a bigger view. As you can see these so called curves are just straight line segments. Some radios like the JR 8103 and 10X have an 'expo' mode that rounds the points to make them true curves. The high end radios show you this chart while the others only show the numbers. It really doesn't take much imagination to visualize what 5 values would be like on a graph, so although pretty charts look kewel, you're not really missing much by having a radio that doesn't show them. So now you maybe wondering what curves and servo output have to do with flying. In this example we have a pitch curve of 15,70,90 and a throttle curve of 20,40,50,60,100. When you move your left stick all the way down then your pitch is at 15% and the throttle is at 20% (with idle trim up). As you move the stick up to center position the pitch goes to 70% and the throttle goes to 50%. So you can see that as you move the stick the radio tells the servos where to go according to the throttle and pitch curve values you put in. The next question you might have is how do the percentages relate to the actual pitch of the blades and movement of the carbureter of the engine. Lets say you have a pitch curve in the radio of 15,70,90 and the blades have an actual pitch range of -9 to +11. The values in the radio range from 0 to 100. So 0% would move the servo and blades on the helicopter to give a pitch of -9 degrees, 100% would make the blades go to +11. -9 to +11 is a total of 20 degrees of movement. 0 to 100 in the radio represents these 20 degrees, 100 divided by 20 gives 5, so for every 5 points in the radio that equal one degree of movement of the blades. So in the example radio pitch curve (15,70,90) that means the blades would be at -6 when the left stick is all the way down and +9 when the when the stick is all the way up. If your pitch curve was 100 on the top, then you would have +11 if the left stick was all the way up. This all works the same for the throttle but instead of measuring pitch angles, you are just opening or closing the barrel of the carburetor.
|What is Dual Rate?||This feature is used to help the learning process for novice pilots. A value of 50% dual rate would cut the total servo travel by half. The makes the heli less sensitive. A good starting value is about 70%. Increase by 10% as you get comfortable until you reach 100%. If you are beginning forward flight, but still think 100% is too touchy, then use about 30% Expo with 100% dual rate.|
|What is Expo?||Expo's purpose is to make the control less sensitive around center but still allow full roll rates and full stick. A good starting point is about 30%. Use this feature if the heli seems too touchy while doing hovering maneuvers.|
|What is a gyro?||It is a device used to sense sudden unwanted movements of the tail. It's job is to move the tail servo to compensate for the unwanted movement. As an example, lets say you are in a hover and a sudden gust of wind blows the right side of the helicopter. Without a gyro this would cause the helicopter to turn to the right. With a gyro, it very quickly senses the sudden movement and gives a left command to the tail servo to keep the helicopter pointed where it was. This is just a simple example, the real benefits of a gyro come into play during aerobatics.|
|What is gyro gain?||This refers to the sensitivity of the gyro. When the gyro senses an unwanted movement it commands the tail servo to move in the opposite direction to compensate. How much it tells the servo to move is the 'gain'. Ideally the amount of gain should match how much the helicopter was rotated so that it stays pointed in the same direction and does not move. If the gain is too high then the helicopter over compensates. The effect you will see is the tail will bounce back and forth. If the gain is not enough then you will notice the tail does not hold very well. When setting the gain, you want to turn it up until you see the tail 'hunt' (bounce back and forth) then turn the gain back down until it stops.|
|What is remote gain?||This means the gain can be adjusted in the radio. A non-remote gain capable gyro has a control on it that you use a screw driver to turn for more or less gain. A remote gain capable gyro has an extra plug that goes to the gear channel. With this type you can use the gyro menu in the radio to adjust the gain. If it's an older or cheaper radio that does not have a gyro menu, then you can use the gear ATV to adjust the gain.|
|What is the difference between a standard gyro and a heading hold?||A standard gyro just dampens unwanted
movements of the tail. To keep things simple lets say you
are hovering and several gusts of wind hits the
helicopter from the side, the gyro will keep the
helicopter from suddenly swinging nose into the wind, but
the helicopter will eventually drift nose into the wind.
A heading hold gyro will keep the nose pointed in the same place until you tell it to move. You can fly sideways with the rudder stick in the center and the nose will remain pointed in the same direction.
If you have not used heading hold before then you will notice in fast forward flight that when you make a turn, the tail will not follow the helicopter, you have to give some rudder in your turns. Another thing is that you'll notice the rudder stick feels different. In heading hold, the amount you move the rudder stick from center tells the gyro how many degrees per second that you want the helicopter to rotate. The gyro moves the rudder servo however much it needs to obtain the requested rotation rate. With a standard rate gyro if you did a slow pirouette (one rotation) with the wind then to keep the helicopter spinning at the same rate you would have to move the rudder stick more as the tail is going upwind and less as the tail goes downwind. But with a heading hold gyro, it will tell the rudder servo to move more or less to maintain the constant rate, you just keep the rudder stick in one place.
Note: Heading hold gyros can be switched to operate in standard rate mode if the user wants to.
|Heading hold gyro gain?||The biggest misunderstanding is how the
values in the radio relate to the gain amount. The values
may seem a little confusing. Depending on which radio you
have and how you set it up, there are a couple of ways
the values could be displayed.
1) If your radio has, and you use, the gyro function, then the value range will be from 0 to 100. Because this signal also tells the gyro which mode (standard or heading hold) the range is divided in half. So 0 to 50 could be standard rate mode and 50 to 100 would be heading hold mode. The further you get from 50, the higher the gain will be. As an example, 15 and 85 would both be a high gain setting. (50-15)*2=70% gain, (85-50)*2=70% gain. The only difference is that one side of 50 tells the gyro to go into heading hold mode and the other side tells the gyro to go to standard rate mode. Note: Your 0-50 side maybe the heading hold mode, if you want to change it, go to the servo reversal menu in your radio and go to the gyro channel and change the direction.
2) If you don't have a gyro function and you use the end points (ATV, EPA) then your range, depending on the radio, is usually displayed as -100 to +100, -125 to +125, or -150 to +150. Different brands choose a different way to display it. In any case the signal the receiver sends to the gyro is always the same 1 milli-second to 2ms. So if one brand uses -100 to produce a 1ms signal, another brand would use -125 for 1ms, and another brand would use -150 for 1ms. As an example lets say we have a radio with a range from -150 to +150. This is common with JR radios. 0 would be the center and the further you went away from 0, the higher the gain would be. To calculate your gyro gain with a value of -110 you get (-110)/(-150)=73% gain and since you started with a negative value, that means the gyro is in standard rate mode. Note: Your negative side maybe the heading hold mode, if you want to change it, go to the servo reversal menu in your radio and go to the gyro channel and change the direction.
|Can I use the built-in pitch gauge on my Raptor 30?||Yes, if you first set the two long links (pg. 12, step 12, item 4) to 100mm. This might very slightly from 100mm to 102mm so to get a perfert match you would have to use an accurate pitch gauge placed on the blades and set to 0. Then move the pitch arm to align with the 0 center mark. Then adjust the links to get the blades set at 0 degrees.|
|What is flight mode 1, 2, and idle up||Flight mode and idle up refer to the same thing. This mode is activated with a switch that is usually on the top/left of the transmitter. You start out in Normal mode for hovering and switch to flight mode for fast forward flight and to do 3D type tricks. The radio lets you set seperate throttle and pitch curves for each mode. So in normal mode you would have the pitch range from +9 to -4 (depending on skill level) and when you flip to flight mode 1 then you could have the pitch range from +9 to -9 and have the throtle set to a v-curve so the engine doesn't go to an idle when you go upside down. Some radios have a 3 position flight mode switch so you can setup a 2nd flight mode. You could use this to run a higher rpm or what preferance you would like.|
|It appears as though the main body of the aircraft is crooked or at an angle???||That is normal for the heli to hover crooked. The full size ones do it too. Watch when they lift off and you will see one skid lift before the other. You may not have noticed it before either because of wind counteracting the lean or you were paying attention to flying. You probably noticed it now because your senses were heightened on the first flight after a near crash. Normally people don't notice this because they have grown so use to it while they were learning to hover. When you get to doing nose-in hover this crookedness really stands out. Why does it lean? Because of the position of the tail rotor. The center of thrust of the tail rotor is below the center of the main blades. For a clockwise rotating helicopter this offset thrust causes the helicopter to tilt to the left. Just the opposite for a counter-clockwise rotor. You may notice that on some of the full size (and some scale model helis) that the tail is angled up to put the center of thrust from the tail at the center of the main rotor. This type will not have the common 'lean'.|
|How do I break-in a new engine?||First, what does it mean to break-in an
engine? When an engine is new, the piston and sleeve
inside the engine has additional resistance because their
surfaces don't perfectly match. After an engine is broke-in
the inside surfaces have worn together and provide a
smooth motion. During the first few runs, the engine will
be hotter then normal so you need to keep it a little
rich. Not excessively rich, an ABC/ABN engine won't wear
in good if it's too rich. After the first few tanks, you
will notice the mixture settings will drastically change.
This is normal.
I know some people say break the engine in on the bench, but I do mine in the helicopter. The bench does not provide the same operating conditions as what the engine will be used for. For the first tank, I do 1 to 2 minute hovers, then let it idle for a minute to help cool down. On the 2nd tank, I just do hover with slow movements. You will notice the needle settings have to be changed as the engine is breaking in. After this happens I gradually get more aggressive with the flying. I usually feel safe to do 3D with it after 10 tanks. Stay on top of the mixture changes. Don't let the engine get too lean during break-in, you don't want it to break :)
|How long before I have to charge the batteries?||You need to have a way to check the voltage
of the batteries. You can buy r/c volt meters for $5-10.
They have a section of the scale marked red, then white,
then green. If the needle points in the green then you
can continue flying. Charge the batteries when you get
into the white.
If you don't have one of these meters I highly recommend spending the few bucks to get one. If you can spend the extra, the BC6 and Gem2000 are nice battery monitors. If you must fly without a way to check the batteries, then as long as you charged the batteries fully and you don't have any servos binding or too much resistance on the control system, then you should be able to safely get four flights from an 1100mah battery. I have a 1400mah battery and get 10 flights with 3D type flying, so you can probably get more (as long as you don't have an old mechnical gyro), but it's usually bad to 'assume' things, get a meter :) Note that different servos may use more energy so where I get 10 flights, you might only get 5.
|Is there a good book about r/c helicopters?||I have heard that Ray's Authoritative Helicopter Manual is a very good book.|
|Should I setup the radio to hover at 3/4 stick?||I know some people say to use this technique, and what you choose is up to you. I will tell you what I think about it and you can decide. First off what do I use? I use the standard setup where I hover at half stick (well near half stick for my specific setup). So why use the other method? The idea behind hovering at 3/4 stick is so that later after you advance your skills and start flying in flight mode 1, then when you flip the switch the helicopter won't jump on you... Now you're asking what do I mean 'jump'? Well let's look at an average setup. After you advance your skills a typical configuration would be: Normal flight mode -4,5,9 and flight mode 1 -9,0,+9. So imagine you are hovering in normal flight mode with the stick in the middle, that would be at 5 degrees, then you flip to flight mode 1. Your stick is still in the middle so now all of a sudden you just switched from 5 degrees to 0 degrees. So what does the helicopter do? Yep it just went down quickly. Now if you are in flight mode 1 and you are hovering, which means you are at 3/4 stick, and you now flip to normal flight mode, then now your pitch has jumped from about 5 degrees to about 7 degrees. So the idea behind the 'hover at 3/4 stick setup' is that your pitch curve is the same when you flip between flight modes and therefore the helicopter does not 'jump' on you. This makes sense, so why don't I use this? It's because you lose hover resolution and unless you have a $1000 radio you also lose the key points in the throttle curve that you use to get good performance. By resolution what I mean is how sensitive your collective stick is. If you hover at mid stick then you have the entire range from mid stick to top and mid stick to bottom. But if you hover at 3/4 stick then that cuts your range in half, thereby making it twice as sensitive. Another thing is with a mid-stick-hover setup that gives you a throttle point to adjust in the middle and one above and below. Usually you setup the 1/4 and 3/4 points to be 10% above and below the hover point. This helps to give a very smooth hover and with the 1/4 point being high that keeps the throttle up while you are making a descent. If however you have a 3/4-stick-hover setup then unless you sacrifice the top throttle point then you won't have a smooth transition from hover going up. You could solve this with an expensive JR 10X or Futaba 9Z if you have one. Another thing is with 3/4 stick hover you no longer get to use the convenient hovering throttle trim found on most radios. So if the mid-stick-hover is what I use then what do I do about the 'jump'? Simple, I just go to 3/4 stick anytime I switch from normal to flight mode 1 or from flight mode 1 to normal. At 3/4 stick the pitch is the same in both modes. Also as I improved my skills to the point where I wanted to start using flight mode 1 for more advanced things, I also changed my middle point in the pitch curve of normal flight mode. So instead of mid stick being at 5 degrees I changed it to 4 degrees. That means I hover just a little above center. This also helps the transition. Some may say "I'm only in normal mode to take off then I stay in flight mode 1 so why worry about normal flight mode?" Well if all you do is 3F (Flip, Flop, Flying) then don't worry about normal mode, but for me I like normal mode for nice smooth ground maneuvers like slow pirouetting circle's, backwards figure 8's, and just some nice finely controlled landing approachs.|
|Get the tail on right!!!||Click <here>|
|How do I measure the head speed?||The Miniature Aircraft SkyTach works the best. You not only can measure the head speed in a hover, but also while the helicopter is performing maneuvers up high. You do have to have someone else do the measuring while you fly so if you fly alone then an alternative would be to use the tail boom mounted tach that ACE/Thunder Tiger sells. This will work fine for measuring the head speed in a hover.|
|How do I measure the blade pitch?||I use the pitch gauge made by Miniature
Aircraft. There are many different brands out there,
whichever one you use place it on the last 1/3 of the
main blade. This is the part of the blade that counts the
most. The last 1/3 is where almost all of the lifting
force comes from. Level the flybar, sight down the pitch
gauge and rotate it until the top edge of the gauge is
parallel with the flybar. When finished checking one
blade, make sure you rotate the rotor head 180 degrees
and then check the other. If you just move the pitch
gauge to the other blade then you could get a different
reading because the swashplate may not be perfectly level.
If you don't have a pitch gauge then you can use the built-in pitch gauge on the Raptor but you have to first align it. To align it, move the pitch arm until the end points at the 0 degree mark. Next adjust the two long links going from the swashplate up to the head so that each blade (as viewed from the end) is parallel with the flybar.
|How do I hold the radio?||Read <this> page.|
|How many flights per charge?||This depends on the size of the batteries and
the servos you run. I get 8 flights at 12 minutes each
doing 3D flying on my 4.8V 4 cell Nicd battery pack that
is made of 1700 mah 'A' size cells. I use three Futaba
9202 servos, one Hitec 525, and one Futaba 9253 digital
servo. If you use all digital servos then 3 to 4 flights
would be normal.
Note: If you have tight links or an incorrect radio setup that allows the servos to bind then you will greatly reduce your flight time. <Here> is an article on finding tight links.
|How big should the battery be on the helicopter?||Often times the battery is used to help get the CG (center of gravity) of the helicopter under the main shaft. So in this case the size/weight of the battery is choosen to balance the helicopter. On the Raptor 30/50 a 1700mah 'A' size 4 cell pack works great. I used one of these on my Raptor 60 and it also worked good but on the 80/90 (longer tailboom) or if you use a rear tail mount then you may need to use a sub-c size pack.|
|How often should I check the batteries?||Before the first flight and at the end of
every flight. The reason for checking the batteries at
the end of the flight is because the battery will be at
its lowest. If you let it sit a while the voltage will
build up and give an inaccurate reading of the usable
If you have an on board battery monitor like the Gem2000 then right after you turn off the engine watch it while you move the right stick in a quick circle. If it indicates low then you need to charge the batteries before you fly again.
Most modern radios will beep and flash a message to indicate the battery needs charging. If you look at the voltage on the display at the end of the flight then as long as it is above 9.5V then you can fly. Once the voltage drops below 9.6v it will go down fast.
|What should the voltage be after a charge?||Using a standard r/c battery meter with a 300mah load you will get 5.5 volts on a 4.8v (4 cell) pack. And about 6.9 volts on a 6v (5 cell) pack. The radio battery will read 10.8v|
|What is the lowest voltage I can fly with?||For the receiver once it drops below 4.8V then do not fly it. This is for a 4 cell nicd pack. For the radio, 8 cell nicd, the alarm on it should go off once it goes below 9.6V.|
|Lithium-Ion batteries / Nickel Metal Hydride||I do not have any personal experience with the use of these type batteries in the r/c hobby. The best place to find accurate information is R/C Battery Clinic. At this time I know of some issues with these packs. Li-Ion has an open type failure mode compared to the short type for nicd. So when a cell fails it opens the circuit. To counteract this some Li-Ion packs are doubled up so that for each cell there is another one in parallel. For both Li-Ion and Nimh they do not have as much sudden surge current that nicds do. Fast charging is another issue. While Nimh can be fast charged it does take longer then nicd's. Now Li-Ion takes a long time. You can get a higher capacity pack to fly more but when the battery is down do not expect to charge it at the field and fly again that day. With Li-Ion each cell is 3V so this type pack will be 6 volts. Some items like gyros do not run on the higher voltages so you will need to use a regulator. You will need to look at the specs for each of the electronic devices (servos, receiver, gyros, etc) that you want to use. Also remember that you need a battery monitor that is rated for the battery pack you use. Another issue is the type charger you use. More chargers now do Nimh but not many do Li-Ion. Also keep in mind that per capacity Nimh and Li-Ion are lighter then Nicd. So you can use a higher capacity and still keep the CG (center of gravity) of the helicopter under the main shaft.|
|Life expectancy of the battery||There are many variables so it would be hard to pin point an exact time. Basically when you see you are getting less flights per charge then it is time to change it. If you have to have a number then all I can say is I replaced one pack so far, it had 800 flights on it at the time. If you read R/C Battery Clinic then he suggest changing the battery every year. The life of a battery is dependent on how you treat it. Of course if you smack it in the ground then that would not do it any good hahaha. While that is obvious other things may not be such as the way you mount the battery. I see a lot of people just stick the battery on the radio tray with some double sided tape and although the manual that comes with the helicopter shows this is how it should be, that is not the way I recommend. I use foam weatherstripping tape as shown <here>|
|What kind of charger||The radio comes with an overnight charger that will charge the radio and the receiver batteries at the same time. This will take about 10 hours. If you want to fly a lot each day then you need a quick charger. The best value for the money is the Hitec CG-340. It sells for $35 USD. Now if you have the money then for $130 USD you can get the <Triton>.|
|Is it ok to quick charge the battery||Nicd's and Nimh can be quick charged but not Li-Ion. I charge my Nicd's at 1C most of the time but never more then 2C. 1C means the same as the capacity. So my 1700mah receiver batteries get charged at 1.7 amps. Now my radio battery is charged at 0.9 amps. The battery pack is 600mah so that is still less then 2C.|
|Watch the polarity of your charge jacks.||If you have a flying buddy that needs you to charge his radio then make sure you have the charge cord connectly correctly. If you use Futaba, Hitec, or Airtronics but your buddy has a JR then you need to plug your charge cord in backwards. The same goes if you have a JR but your buddy has another brand. As for the battery on the helicopter all of those plugs have the same polarity. The one exception is the old style (non blue color) Airtronics connectors.|
|What is the difference between a 6v and 4.8v battery||6 volt receiver batteries have (5 cell for Nimh and Nicd) have the advantage that it makes your servos faster but the disadvantage is that you get less flight time. Some people get confused on this and they think the more voltage the more flight time they will get. It is simple ohm's law, if the load (your servos) remain the same but the voltage is higher then the current draw will be more I=V/R. Another disadvantage is that some electronic devices do not run on 6 volts. For instance the specifications on the popular GY401 gyro indicate an operating voltage range from 4 to 6v. A 5 cell nicd or nimh will be nearly 7v when fully charged so a regulator is needed to drop the voltage down.|
|My charger did not put in the full capacity||Some of the upper end chargers display the amount of Mah (milliamp hour) that it took to charge the battery. The amount that it puts in will be less then the rating on it. I often fly my 1700mah battery until the gem2000 (battery monitor) goes solid when moving the sticks at the end of the flight. After the engine is off I move the cyclic stick in a circle and watch the blinking Gem2000 light. If it goes solid then I charge the batteries before flying again. At this point it usually takes 1300mah to fully charge the 1700mah battery.|
|Can I use other brand servos?||Yes. The one exception is the old style (non
z type) Airtronics. Those receivers and servos can be
used with other equipment but you have to swap the
positive and negative wires.
When connecting a Futaba servo or gyro to another brand it is necessary to remove the 'key' from the plug. That is the flat piece on the side of the connector. I just use standard diagonal cutters to cut that piece off.
|Why do my digital servos 'buzz'||They are very accurate and are making micro corrections constantly to obtain an exact position. When they are new the gears inside are a little rough and it makes the servo continually hunt for that exact position. As the gears wear in the buzz will go away. The non-digital servos are accurate but they only update their position about every 20 milliseconds (dependent on the type transmission PPM/PCM and how many channels the radio has). The digitals are making corrections full time.|
|Glossary of terms|
|Trim||There are four trims on the radio. One each corresponding to each stick direction. The throttle trim is used to set the idle speed, but the other three are used to center the aileron, elevator, and rudder. So if you are in a hover and notice you have to keep the elevator stick pushed forward just a little, then you could add a few clicks forward on the elevator trim.|
|Sub-Trim||This essentially does the same as trim, but it applies to all flight modes. On most computer radios with digital trims, the regular trim maintains indepent trim settings per flight mode. Ideally instead of using sub-trim you should adjust the links on the helicopter to acheive centering. One practical use for sub-trim is to eliminate overdriving when using cyclic to throttle mixing. Another use is if you do not have a position the servo arm will fit on the aileron servo to give a 90 degree fit, then you can use the sub-trim to adjust for the right angle.|
|Pitch||This refers to the angle the main rotor blades are at. When you see a comment about having +9 pitch, that means that the blades are tilted at an angle of 9 degrees and because it is positive (leading edge up and trailing edge down) that will make the helicopter go up. A -9 (leading edge down, trailing edge up) will do just the opposite and make the helicopter go down. When you are at a hover with the helicopter not going up or down, then you are about 5 to 6 degrees positive pitch.|
|Cyclic||This is the right stick (mode 2 configuration) which controls the aileron and elevator. Cyclic refers to both of these controls.|
|Aileron||The left/right movement of the cyclic stick.|
|Elevator||The up/down movement of the cyclic stick.|
|(Gyro) - Remote Gain||This refers to a feature that lets you adjust the gyro gain from the radio as opposed to old gyros that had to be adjusted directly on the gyro. Most modern computer radios have a gyro function built-in that let you select different gain settings for each flight mode or assign the function to a switch.|
|(Gyro) - Single Gain/Dual Gain||"what is the difference between dual gain and single gain gyro's?" Single gain gyros have a manual pot on the gyro box that you use to set the sensitivity of the gyro. Dual rate gyros have two pot adjustments. In addition they have a plug that you connect to a spare channel on your receiver. Then you use a switch on your radio to switch between two different gain settings. You can use a very high gain for hovering then switch to a little lower gain for flying around. The reason you would want to switch to a lower gain is when you switch to flight mode you usually have that mode set for a higher head speed. This higher head speed also means the tail speed is faster and therefore more effective, so you would get a tail wag until you switch the gain down.|
|D/R Dual Rate||This function applies to the Aileron, Elevator, and on some radios also applies to the rudder. The term dual means two and rate means the sensivity of the control. You can set a switch on the radio to toggle between two D/R settings (ex. switch up 100% and switch down 50%). With a D/R of 50% on the elevator the feel would be very soft since the servo only moves half as much as if the D/R was at 100%. D/R is good to use for people just starting out learning to hover. New pilots have a tendancy to move the sticks too far and with D/R for the elevator and aileron set to 80% or less it helps. Later as they get comfortable wtih the setting they can gradually increase it to 100% so they have full servo movement. Note: It is important to have D/R set to 100% when you are doing a setup on the servo otherwise you would never get the end points set right.|
|Expo||Expo is short for exponential. The effect you see by using this function is that the sensitivity is soft around the middle but still has full servo travel at the ends. On all radios except Futaba, the more you increase this value the larger the area around center is soft feeling. For Futaba you have to go negative. So -20 on a Futaba would be the same as +20 on all other radios. Zero would be no expo. When I setup a radio for someone that uses their thumbs to control the sticks I often put 30% expo on the aileron and elevator. For more info on the pinch method versus the thumbs go <here>.|