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Belt Drive Conversion Kit
Thank you for purchasing our belt drive upgrade kit. This kit was designed to address specific issues pertaining to tail authority as well as reliability of the stock tail drive system.
The stock tail drive uses a ratio of 1 to 2.1 (main rotor to tail rotor). This means that for every revolution the main rotor makes, the tail rotor turns 2.1 times. Our belt drive ratio is 1 to 2.8. This is 30% over the stock ratio. Increasing the drive ratio accomplishes two things; #1 It gives much better tail response. #2 It gives much better tail holding authority (When a tail wind is encountered, the tail will not have a tendency to swing around when our belt kit is used).
A few added benefits of the belt drive are; #1 It is 3 grams lighter than the stock drive system. #2 It is much simpler (fewer moving parts) than stock. #3 It is quieter than the stock drive wire setup. #4 It is much more reliable. No more stripped gears! If the tail rotor gets jammed, the belt is designed to skip with (normally) no adverse affect to the belt. If the belt does get damaged, it is less expensive to replace than a set of gears.
We have done a large amount of research, looking for the ideal drive ratio. Many ratios were tested and we finally settled on 1 to 2.8. This ratio increases tail authority considerably, without reducing flight time too far. We have only found a roughly 5% reduction in flight time with the use of our belt drive (although this is variable depending on the setup of the helicopter). So, performance is way up, while flight time is only slightly lowered.
Different ratios are available as a special order to tailor your helicopter to your particular preference. A lower ratio gives longer flight time. While a tall ratio is better for performance.
Kit Contents
· One toothed drive belt.
· One 28 tooth aluminum main pulley.
· One 10 tooth aluminum secondary pulley.
· Two main shaft spacers (adaptors for stock main shaft and 5mm oversize shaft).
· One carbon fiber idler wheel mount.
· Two ball bearing idlers.
· Two screws, two nuts, and washers for idler wheels.
· Three one inch 4-40 screws for mounting the idler assembly to the tail boom clamp.
Assembly Instructions
STEP ONE-- Remove the tail boom, main shaft and rotor head assy.
STEP TWO-- Remove stock drive wire, and related gears, as well as the tail boom
Bushings (the belt drive requires a hollow boom).
STEP THREE-- Remove the aluminum tail shaft.
STEP FOUR-- Remove the stock orange plastic gear from the tail shaft. (See below)
Once the tail shaft is removed from the helicopter, place the orange gear on the edge of a workbench and (using a soft faced mallet as pictured above) tap the aluminum shaft out of the gear.
STEP FIVE-- Install the ten tooth aluminum pulley on the tail shaft as shown below.
Mount the pulley ½" from the end of the tail shaft.
STEP SIX-- Reinstall the tail case on the tail boom (make sure the plastic bushings have been removed).
STEP SEVEN-- For step seven, please refer to the picture below.
Feed the drive belt through the tail boom as shown. Feed the belt all the way to the tail case. Make sure the end of the belt is visible in the tail case when viewed through the side of the case as shown below.
STEP EIGHT-- Insert the tail shaft with the new aluminum pulley through the tail case making sure the belt loops around the pulley properly as shown below.
STEP NINE-- Reassemble the tail rotor assembly.
STEP TEN-- Install the completed tail assembly on the crutch as shown below (Do not screw the assembly to crutch yet).
IMPORTANT!! When installing the tail boom and main shaft assembly, extreme care must be taken to assure an accurate 90 degree angle between the main shaft and the tail boom. Alignment is very important on a belt drive system. If the alignment is incorrect, the belt may have a tendency to walk off of the idler wheels and be misaligned on the pulleys. It is for this reason that I highly recommend installing a second tail boom clamp (not included in the kit) behind the original clamp as shown above. This helps keep the tail boom from moving unintentionally.
STEP ELEVEN-- Reinstall the main shaft with the main pulley (be sure to install the correct pulley spacer on the shaft. Two spacers are included. One spacer is for the stock main shaft and one spacer is to be used with the 5mm oversize main shaft kit our company sells). Slide the main shaft and pulley through the belt as shown below.
IMPORTANT!!! At this point you will notice that the belt twists 90 degrees as it runs trough the tail boom. Care must be taken to assure that the belt is twisted in the correct direction. The key to this is to make sure the tail rotor rotates backward when the main rotor rotates in the proper direction. If the tail rotor rotates incorrectly, simply pull out the main shaft and twist the belt in the other direction.
STEP TWELVE-- Install the idler bearings on the carbon fiber idler mount with the screws and nuts provided as shown below (make sure the idler bearings spin freely after mounted).
The belt kit includes a few small washers that can be mounted under the idler bearings to shim the bearings up if required. A little extra care taken with shaft/ boom alignment as well as properly aligning the idler bearings will ensure a long life span for your belt drive.
STEP THIRTEEN-- Mount the completed idler assembly on the tail boom clamp making sure the belt runs between the idler bearings as shown below. Be sure to use the one inch screws provided in the belt kit.
At this point, belt tension should be set. Belt tension is adjusted by simply moving the tail boom forward or backward in the clamp. I recommend setting the tension snug, but not too tight. A simple test is to hold the main gear while turning the tail rotor. The belt should be snug enough to allow the belt to skip under stress, but not to skip in normal flight. This takes a bit of experimentation to get right. But it is not a difficult task.
Now, the last step is to reassemble the rest of the helicopter and go ahead and fly it!
Go ahead and test run the helicopter on the ground. Make sure (as stated above) the tail rotor is rotating backward. Second, make sure the belt does not skip when power is applied. Once everything is tested and ready to go, take the helicopter up and hover at chest height about 15 feet in front of you. Turn the tail 90 degrees left and 90 degrees right. Get a feel for the tail response before getting too aggressive with your flying. You will notice an immediate improvement in tail response as well as gyro response (remember, your gyro is at the mercy of the tail rotor's ability to control the heli). You will also notice an increase in tail authority in windy conditions.
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