The Helicopter Doctor |
Last updated 9-3-2003
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Bayside RC Club rules require all pilots to present their AMA membership card. No flying, even on a buddy box, without proof of AMA or a Club membership card in your possession. Non members are welcome to fly during a limited number of visits as a specific guest of a Bayside Member. Guests must have proof of AMA in their possession. You are most welcome to join our club, but you are not welcome to use the facilities forever without paying your fair share. The following is provided for all helicopter pilots from rank "newbie" to the experienced 3D flyer to help them insure their machines are ready and safe to fly. If you come to Bayside for beginner's instruction, you can expect your instructor to go through this list with you and your machine before you ever get a chance to fly. |
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Helicopter Airframe Safety Check |
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Battery to Switch connector |
Secured by secondary means |
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ON-OFF switch |
ON is DOWN or BACK; OFF is UP or FORWARD "ON" on the switch plate indicates when receiver is actually ON |
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Receiver Antenna |
Secured to airframe Protected from chaffing and/or tension stress Routed to insure no mechanical interference with servo links, blades or tail rotor. If antenna is Dean’s Whip, whip is secured at two points, to minimize vibration |
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Servo wires |
Protected from chaffing Routed to insure no mechanical interference |
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Balls and Ball Links |
Pull-Test each link (Pull should "tip the heli" before link disconnects) Screws and nuts holding balls should be CyA’d Clevises have fuel tubing "keepers" installed (typically on throttle and tail) |
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Push Rods and Servo Horns |
Servo-horn screw is present and tight on each servo Throttle control arm is tight on throttle shaft (pop the link and twist it) Servo-horns have no mechanical interference throughout their travel Push rods and ball-links have no mechanical interference throughout their travel |
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Main Rotor Blades |
No visible damage to tips, edges or roots, No sounds when flexed or twisted. No visible damage to blade holders Root-Plates glued to blade (covering removed) and lead weights are glued in. No interference with tail blades |
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Tail Rotor Blades |
No visible damage to blades or blade holders |
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Electronics Package (Receiver, Battery, Gyro-control box) |
Wrapped in vibration damping material Secured to airframe |
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Gyro |
Mounted to airframe with appropriate foam tape Freedom from mechanical interference |
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Loose Screws |
Flex side frames, servo tray, landing gear, tail fins Flex Main Rotors looking for loose control arms or links Flex Tail Rotors looking for loose control arms, sliders or links Twist Tail-rotor box looking for slip at the boom Twist Tail boom looking for slip at the front mount |
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Fuel Tank |
Fuel feeder line (should have filter) is not kinked or pinched Muffler pressure line is not kinked or pinched. Fuel lines have no mechanical interference with clutch, fan, main-gear, servo controls or hot engine parts. Fuel Cap firmly attached and not visibly leaking |
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Battery check with ESV |
Check for >4.5v (typically >5.2v for fully charged four cell pack) |
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Battery check with onboard voltage monitor |
Check for indication of >4.5v after 1 min warm-up Check voltage indication when all servos are moved through their normal range Check voltage indication when each servo is "mildly stalled" by finger pressure |
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Transmitter Safety Check |
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Frequency Pin |
Explain transmitter impound and frequency control rules. Pin is present and matches Transmitter crystal frequency |
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Transmit Frequency |
Frequency marked on Crystal matches channel-number tag on Transmitter |
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Transmitter Antenna |
Antenna is securely attached All segments are present |
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Battery check |
Transmitter voltage indicator >9 v (should be >9.6v if fully charged. If in doubt use ESV or loaded DVM) Transmitter RF indicator >80% |
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Switches |
All mode switches are operable or disabled |
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Transmitter ON Checks |
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Check AMA card Get the frequency pin |
Throttle direction (Low-stick is low throttle and Low-trim kills the engine) Pitch, Elevator, Aileron, Rudder direction and travel limits (watch for curves) Gyro direction, dual rate control direction and levels. |
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Range Check with PPM (FM) receiver |
Transmitter antenna collapsed (one segment max extension) Carry Heli away from transmitter until servos start to "chatter" or "vibrate" Rotate Heli through 360 degrees in both horizontal and vertical axis to check for additional "chatter" Move closer until "chatter" disappears If distance is >50 feet in "worst" orientation, OK to fly. |
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Range Check with PCM receiver |
Transmitter antenna collapsed (one segment max extension) Set Throttle Fail-Safe to IDLE, and Throttle stick to MAXIMUM. Carry Heli away from transmitter until throttle servo goes to IDLE (F.S. indication) Rotate Heli through 360 degrees in both horizontal and vertical axis (check for F.S.) Move closer until there is no Fail Safe indication. If distance is >50 feet in "worst" orientation, OK to fly. |
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Novice Helicopter Bench-setup |
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Transmitter setup starting point |
All ATV’s set to 100% All Stunt Modes inhibited All programmable mixes inhibited REVO inhibited Pitch Curve inhibited (linear 0-100%) Throttle Curve inhibited (linear 0-100%) Throttle-Hold (Inhibited for Newbie maybe Enabled for experienced pilot) Dual Rates inhibited Expo inhibited Sub Trim or Trim Memory cleared (0%) Modulation Type set to match Receiver (PPM or PCM) Throttle Kill enabled on radios with digital trim Check high-end Futaba transmitters for "cross-trim" |
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Ch# |
Futaba Hitec |
JR Airtronics Stylus Airtronics Infinity 660 |
Airtronics RD6000 |
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1 |
AIL |
THRO |
ELEV |
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2 |
ELV |
AILE |
AILE |
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3 |
THR |
ELEV |
THRO |
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4 |
RUD |
RUDD |
RUDD |
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5 |
GER |
GEAR |
GYRO |
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6 |
PIT |
AUX1(PITCH) |
PITCH |
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7 |
AUX1 |
AUX2 |
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8 |
AUX2 |
AUX3 |
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Servo Linkage setup Transmitter ON Get the pin (This step can be done without the transmitter, but ZERO has to be re-set with transmitter ON) |
Except as noted in assembly instructions (re-read the instruction book carefully); Place both sticks at mid position (zero trim) and adjust linkages for the following; - All servo horns at right angle to push rod (Rotate the horn at the servo to get best angle. If not 90 degrees, trim it out) - Pitch slider or pitch lever positioned at mid point between mechanical limits - Swash plate level (viewed from the side and from the front) - Washout arms level and parallel - Main Blade Pitch set to 4-5 degrees - Tail Rotor pitch lever at right angles to push rod - Tail Rotor blade tips about 1" when folded (check direction of pitch) - Tail Rotor push rod should not flex or bow when servo load is applied (tape it down where the bowing occurs) - Throttle control lever at mid point of mechanical travel limits |
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Servo Endpoint Adjust |
Set ATV on each channel to avoid mechanical interference or servo binding. If links are correctly sized, ATV should be approximately 100% If ATV is not 100%, min and max ATV should be approximately the same. Throttle Full open and Full closed should be at the same ATV setting (for example +80% and –80%) Set Throttle Kill switch and/or trim position and Throttle HOLD switch. |
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Swash Plate phasing |
Rotating half of Swash plate aligned with fixed half when main blades are aligned with tail boom. (Loosen and readjust as necessary) Otherwise; With main blades aligned parallel to boom, NO main blade pitch change with Elevator control (Fly-bar paddle will have MAX deflection) NO Fly-Bar paddle pitch change with Aileron control (Main blades will have MAX deflection) |
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Main Blade setup |
Fly-bar paddles parallel to each other and to control arms Fly-bar control arms parallel and level when swash-plate is level Set mid-stick pitch to approximately 4-5 degrees Pitch min and max should be limited by a pitch curve, if available. If there is no pitch curve, use Pitch ATV to limit min and max as follows; Limit pitch travel for first flights to +1 degree (LOW) and +8 degrees (HIGH) (After stable hover is routine change to –1 degree to +8 degrees) Apply a piece of "tracking tape" on one blade (a small piece, 1"x ½ ", of brightly colored trim tape applied to the leading edge-tip of one blade) |
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Engine and drive train setup |
Inquire about method used to tighten prop-nut (STOP if there is no mention of "piston-lock", "removal of engine back-plate" or "removal of carburetor". Remove engine and re-tighten prop nut NOW) Check gear mesh Check tail drive belt tension Check for tail drive connection by turning Tail rotor while holding Main Blades Check Tail Rotor direction of rotation. (Top Rotor Blade moves to rear) Check starting shaft for proper engagement and release Check for clutch drag while turning starting shaft. Set main fuel metering needle for 1 ½ to 2 turns out Check Idle Screw for factory setting (only if it might have been changed from factory setting.) (Disconnect Throttle linkage and hold it closed. Manually turn the Idle-Screw CW to stop, then back it out 1 ½ to 1 ¾ turns, Reconnect Throttle linkage) |
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Fuel system |
Check for clunk positioning. (It should be free to move as the Heli is flipped around) Insert fuel filter (suggest Du-Bro "Final Filter") in feed line to Carburetor. Check tank for "loose fit" to prevent foaming. Fill tank to less than half full (filler cap and internal fuel lines still exposed) De-fuel at maximum rate, looking for foaming in fuel filler line (indicates pinhole in clunk-line) Check level where de-fueling stops (tank should be EMPTY. Any residual fuel indicates a problem with fuel clunk) Re-fuel till fuel overflows into pressure line (tank should be FULL. Anything less indicates a problem with pressure line pipe positioning.) Repeat the same tests for header tank, if present. Check for leaks. |
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Transmitter ON checks Check for AMA card Get the pin |
Do the usual Safety checks |
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Rudder and Gyro direction |
With Transmitter Rudder stick held RIGHT, servo arm usually pulls to the front. Check to see that Tail Rotor pitch moves tail to the LEFT if Rudder stick is held RIGHT. (If not, reverse Rudder Servo direction in transmitter) With Rudder stick in the middle, abruptly rotate the Heli to the LEFT and note that rudder servo pulls RIGHT. (If not, reverse Gyro direction) If Dual Rate Gyro, note that the magnitude of Gyro response matches Dual Rate control position. High Rate = Large control, Low Rate = Small control. Set Heading Hold off. If Dual Rate, set both rates approximately equal. |
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Servo direction (check while standing behind Helicopter) |
Transmitter Elevator stick FORWARD tilts swash-plate forward. Transmitter Aileron stick RIGHT tilts swash-plate right. Transmitter Throttle stick DOWN rotates throttle control closed (usually, screws it into carburetor and/or CW. When in doubt, check by listening to exhaust sound while turning engine with starter) |
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Novice Helicopter Engine-running setup |
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Starting Establish a Step-by-step starting drill. Do it the same EVERY time. |
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Basic Carburetor settings |
Set engine to "high-idle" and leave glow heat applied Check to see that "Low trim" and/or "Throttle-cut" kills the engine (Adjust Throttle ATV as necessary. Mechanical adjustment of the carburetor "idle-stop" screw may be required for some engines) Restart and check to see that quick throttle blips don’t lug the engine Check to see the Throttle-HOLD works correctly |
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Hover Carburetor setting Get help from someone who can fly. |
Leave glow heat applied for first hover Advance throttle and note the stick position where head speed approaches lift-off (should be at about half stick) Lift off and note smoke, climbing power and head speed. (Lots of smoke, able to climb without bogging engine, head speed approximately 1500 RPM) If no hovering power and/or low head speed, Lean the main needle 2 clicks (CW) If no smoke and/or HIGH head speed, Richen the main needle 2 clicks (CCW) Repeat until satisfied. Check for fuel foaming in the tank while at hover RPM (If fuel foaming occurs, fuel mixture needles CANNOT be set) Remove Glow heat and note idle speed change (No change is the expected response) |
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Blade Tracking |
Lift off and climb to head height to check blade tracking. If "RED" is high, adjust one of the links on the RED blade to decrease pitch If "RED" is low, adjust one of the links on the RED blade to increase pitch |
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Trim setting |
Note stick positions required to maintain a stable hover. Land and adjust one trim at a time to compensate. Repeat until "no stick pressure" is required. (All trim adjustments must be made in still air or with nose into the wind.) Adjust Rudder trim, Elevator trim and Aileron trim a few clicks at a time in the same direction as stick pressure After the Heli will hover "hands-off" store the trim positions in trim memory or manually adjust control links to move trim back to ZERO |
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Gyro gain |
Increase Gyro gain (or High Gain, if dual rate) and check for tail wag (50% to start) |
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Set the hovering head speed by adjusting Hover Pitch Trim and Hover Throttle Trim, or by adjusting the middle points of the Throttle and/or Pitch curves. |
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If it Hovers; |
<1/2 stick |
1/2 to 5/8 stick |
>5/8 stick |
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Too fast >1600 RPM |
Throttle trim - |
Pitch trim + Throttle trim - |
Pitch trim + Throttle trim + |
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Just right 1400 – 1600 RPM |
Pitch trim + Throttle trim - |
Ya got it!! GO FLY |
Pitch trim - Throttle trim + |
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Too slow <1400 RPM |
Pitch trim - Throttle trim - |
Pitch trim - Throttle trim + |
Throttle trim + |
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After trimming rudder pitch in a stable hover at HALF STICK, adjust revolution mixing to minimize tail movement when ascending or descending. Some transmitters use UP REVO and DOWN REVO others use +REVO and –REVO. (+30% to start) |
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When ASCENDING; (Add RIGHT tail pitch) |
When DESCENDING; (Remove RIGHT tail pitch) |
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If nose rotates LEFT |
If nose rotates LEFT |
Increase REVO (right) |
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IF nose rotates RIGHT |
If nose rotates RIGHT |
Decrease REVO (left) |
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Stuff I wish I hadn’t learned the hard way: ADVICE is worthless unless you understand the WHY as well as the WHAT. Everyone has an opinion on most everything, and unless the context and experience for a suggestion is understood, "your mileage WILL vary". The only thing that you can buy and add to your Heli that will make you fly better is more fuel (burn it). A radio range check that comes up short on the ground doesn’t get better in the air. It’s IMPOSSIBLE to correctly tighten the "prop-nut" on the engine/clutch assembly without something to hold the engine crank shaft, no matter how much Locktite is used. Remove the backing plate or the carburetor and "foul" the crank with a hardwood stick to keep it from turning (NEVER USE a metal tool, and avoid plastic because it leaves particles). A Head Locking tool will also work, but care must be taken not to punch a hole in the piston or bend the connecting rod. Turning the Transmitter "OFF" will not STOP the Heli if it’s chasing you. If you turn the transmitter OFF while the engine is still running, the Heli might do anything, including chase you. Standing with your back against a wall is like being on the wrong end of a firing squad (leave an escape route). After the engine has been tuned, TWO CLICKS on the needle valve is a MAJOR adjustment. Temperature and humidity changes can make the engine run richer or leaner, but one or two clicks should be enough to fix it. If three or four clicks-richer doesn’t fix the problem, look for something else. (Leaky fuel line, crud in the fuel lines, loose muffler, vibration-foam in the tank, dirty carburetor, bad/fouled plug) NOTE: Altitude change is a different matter. 1000-2000 feet altitude change will require ¼ to ½ turn to compensate. A loose muffler will cause the engine to run "funny" (mostly leaner, maybe intermittently). The clues are; "black-oil" drippings under the Heli that come from unusual places and/or a Heli with an oil coating all over the side frames (particularly on the muffler side). A muffler that comes loose in the air will make a TERRIBLE sound. Just land before the engine overheats and loses power. Try not to be so distracted that you lose control. Muffler bolts that won’t stay tight, sometimes can be fixed by tightening them while the engine is HOT. Gaskets between the exhaust port and the muffler can be made from automotive High Temp Gasket paper, and will last practically forever. Don’t grease the main gear because if you do, it collects dust and dirt and then strips. Do Locktite (red) the bearings onto the tail rotor shaft (and/or oil them every flying day) because they will eventually start to slip on the shaft. When the bearings begin to slip, they "fret" the shaft and ruin the rotor shaft, the bearings and the tail box. That high frequency vibration that is seen on the horizontal fin will soon crack it. It also cracks the receiver case; the servo cases and kills the gyro. (Check for a bent tail rotor shaft, bent starting shaft, misaligned clutch, "unlucky" engine-speed resonance.) Medium-speed vertical tail-vibration is usually caused by something in the head being bent or out of balance. (check for bent main shaft, bent feathering shaft, main blade balance, flybar balance, flybar paddle pitch.) Tail twitch and/or horizontal-vibration is usually caused by engine mis-tuning. Adjust the mixture to richen-out of the "lean zone" or lean-out of "the four-stroke" zone. Either zone will cause the engine torque to change intermittently and the gyro will twitch the tail to compensate. Gyro gain that is set too high will cause the tail to wag (oscillate back and forth) uncontrollably. That little glitch that happened as the Heli flew by (but now seems to have disappeared), is still in there. It’s just waiting for a better time to bite you. (Time for a real range check and a careful servo check, as well as looking for loose or broken parts and wires.) That new, little squeaky/rattle sound that the Heli makes while it’s hovering might be an indication of something loose or broken. It won’t get better. (Time for a rattle and squeak check. Look for dirty bearings, loose parts, broken parts, mechanical interference between two things that might move.) Don’t use rotor blades that have been in a crash, even if they "look OK". A rotor blade that comes off a Heli can fly several hundred feet at the speed of a bullet. Don’t be distracted by everyone diving for cover as the machine disassembles itself in the air. By the time you notice that a blade as departed, the entertainment’s almost over. A Tail rotor blade will fly as far and as fast as a main blade, and they are usually aimed directly at you. A thrown tail blade will cause the Heli to disassemble itself in short order. CRC brand spray Brake Cleaner will clean out the crud that gets caught in the carburetor and fuel filter. If CRC Brake Cleaner is used to clean the carburetor, the engine must be immediately refueled and restarted to replace the oil film that protects internal engine parts. If left overnight without this film the engine might seize. Denatured Alcohol (Shellac thinner, $8.00/gal) when used as a spray cleaner quickly removes the oily film from the exhaust that builds up on skids and side frames. A little wiping is all that’s required to clean the Heli. Denatured Alcohol also removes the stickers and decals from the plastic canopy. Use 409 or Windex to clean the canopy. |
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Buy and use a computer simulator: It’ll pay for itself in avoided "crash parts". |
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Buy a book or a magazine: Tutorial books; Ray’s Complete Helicopter Manual, 3rd Edition by Ray Hostler The Basics of Radio Control Helicopters, 2nd Edition by Paul Tradelius Helicopter specific magazines; Rotary Modeler (Color Glossy, short articles, product reviews, lots of pictures, six issues per year) Model Helicopter World (Glossy, many articles, many photos, British, twelve issues per year |
Check the web: The Academy of Model Aviation - District 10 Tower Hobbies RC manufacturers link list Peter Wales' Page (Florida)Peter Wales' Page (England) Peter Wales' Page (Scale Book) Starwood Scale Models (Al Wert)
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