3DX 500 SE / SAH /SAS Flybarless Conversion

We recently converted a Standard 3DX500 SDE head to a Flybarless version as the picture bears witness. It is pretty easy to do yourself as long as you have access to a drill and tap to drill the UGL-09 Item fixing it to the main shaft.

We removed One of the Lower arms as well but you can leave both arms in place as long as you use a grub screw on UGL-09 after drilling and tapping. We used SX 450 Flybarless control rods on our head although you could use stronger control rod arms for safety.

This conversion would be cost effective if you decided to invest in a flybarless control like the Gyrobot 700 or 900 . You can also convert a Lepton with the same mod

Image of the conversion to Flybarless

Flybarless FAQ's

Pilots report longer flight time and more power gain but still there are FAQs.

Rigid Rotor Head from LF Technik

Overview
To answer those FAQ, we need to start with knowing what flybar does and how it works. Flybar is the little seesaw perpendicular to the main blades, it has three missions:

1.Stablization
2.Amplification of cyclic input
3.Compensation for pitch up


1. Stablization

When a rotor head spins, the flybar and main blades form two planes. The centrifugal force makes the flybar plane parallel to the main blade plane. In a perfect "hands free" hovering, these two planes and the horizon are all parallel to each others and remain parallel. Under the external force from wind gust, the rotor plane tilts to an inclination, the gyroscopic force (angular momentum) of flybar spins the plane out of parallel of the rotor plane, the ball link then adjust the individual blade pitch to resist this intervention.

In most cases, the flybar plane itself also affected by wind, although not to the same extent the rotor blade plane, it depends on the mass of the flybar weights. Therefore, it only helps to minimise the inclination.

2. Amplification of cyclic input

Instead of swash plate directly pulling the main blades, the swash plate pulls the flybar cage. Paddles on the flybar utilise aerodynamic forces to change individual blade pitch to amplify the cyclic input. Thus load on the servos are only from the flybar, not the rotor blades; as such, less torque is required from the servo and less wear on servo gears.

3. Compensation for pitch up

In fast forward flight, the leading blade generates an extra uplifting force by impacting the upcoming air current; this causes heli keeps nose higher then commanded. In contrast, the flybar, again with the centrifugal force pulls the rotor plane down by adjusting the individual blade pitch.


Flybarless with electronic device

Flybarless device, in short, is a combination of two head hold gyros along the two cyclic axis; both basically can work individually as the head hold tail gyro. With the ability of memorising the angle of intervened, the cyclic gyros are capable of commanding the cyclic servo to return the heli to the original position; thus providing more stable hover in strong wind.

In contrast to the traditional flybar system, flybarless does having lots of advantages over the traditional flybar system.

Mechanically, removing the flybar assembly simplifies the head structure allowing wider range of cyclic pitch without servo binding; plus cutting considerably amount of weight and slop. Head set up is so simple with as little as only two ball links, blade tracking is very easy.

Instead of commanding how far the servo horn moves, the cyclic input tells how fast the heli to roll or pitch. Reduction in air drag allows wider range of collective pitch without engine / motor bog, on the other hand, EP pilots can use lower power motor and battery pack with the same power output.

In more sophisticated design like the GyroBot, there are devices to help auto level the heli to a complete hands free hover.

Alex provides Tips on a T Rex 450 Gearbox Conversion

Great feedback from one of our customers on converting the T Rex 450 gearbox for a Sonix 3DX450B gearbox click this link to read alex's review in detail
Hope you find it useful if considering the conversion on a V2 T Rex

T Rex 500 Std Head to Flybarless Conversion

We thought this article from RC Heli was worth mentioning for T Rex 500 pilots looking to go Flybarless at a minimal cost. click here and read the article on T Rex 500 Conversion

we sell the Gaui GU365 stabliliser if this mod floats your boat ?

Removing Tight Screws

We have all had a screw that is hard to get out. You know, the one we used that thread locking compound on so it wouldn't come out when we are flying. Sometimes those screws have to be removed to get to a bearing, or just for a good overhaul of the helicopter. Use your soldering iron to loosen up the thread locker without heating up a big area. Just press the tip of the soldering iron on the screw you are removing for about 15 seconds. This is enough heat to liquefy the thread lock and allow you to remove it with ease. Only use this tip on a metal to metal connection, not near plastic components that might melt or elongate from the heat.

Cooling Fan

Some electric models run just a little hot, and it may not always be practical to add a heat sink. If the power system is getting warm and there is minimal airflow, one option is to run a cooling fan to keep the temps in check. There are 5-volt computer fans available, although they may be hard to find. Another source is the small cooling fans made for RC car speed controllers. Novak and LRP both make tiny cooling fans that work perfectly in tight spots to get the air moving.

Needle Valve Extension

Engines often have provisions for a needle valve extension built right in. Sometimes the needle valve is tapped for threads so you can thread a screw into it. A hex head screw works best here because you can easily access it with a hex driver to make adjustments. If you use a screw threaded into the needle valve, be sure to use thread locking compound. This trick can help with making small adjustments easier, especially if you have a nice handle type hex driver. This tip also works great for scale helis, as a small hole will give you access with a hex driver for that hard-to-reach needle valve.

Locking Bolts

Have you ever had a problem securing the screws that thread into plastic? Using a CA bottle can be difficult for those hard-to-reach areas. More than likely you'll have some toothpicks in your kitchen that will make your job easy. Hold the toothpick horizontally and put a drop of CA close to the middle. The toothpick will hold the CA in place until you're ready to put a drop into the hole. Tilt the toothpick vertically over the hole and touch one of the sides of the hole. The CA will drop perfectly into the screw hole, and there is no way that screw will be coming loose.

Remote Glow Plug

Many pilots use a glow plug extension so they don't have to pull off the canopy to light the glow plug. These extensions are prone to the wire failing close to the glow plug connector after a given amount of use, rendering the unit inoperable. This handy tip will get you through until you can replace the extension. Simply strip the wire covering to expose ½ inch or so of bare wire. Pull the wire through and over the edge of some fuel tubing. The fuel tubing can then be pressed onto the center of the glow plug to make a connection. Make sure not to press the fuel tubing all the way to the base. You only want to make a connection with the center pin on the glow plug.

Removal of a stuck bolt

If you strip a screw head, there are a few options to get it out. With either a small file or a rotary tool and a cut off wheel, cut a notch across the head of the screw. Cut the notch to fit an appropriately sized flathead screwdriver, then carefully use the screwdriver to back the screw out. If you do not have enough material to use a flathead screwdriver, you may have to drill the screw out. This is often difficult and not practical, but if you break off the head of the screw, it may be your only option short of a new part.

Neck Strap Safety

Neck straps are a very useful accessory. Many pilots appreciate being able to relax when flying by using support for their radios so they don’t have to hold them up; however, neck straps can get tangled during the process of getting the model started and taking it to the flight line. The biggest danger is the neck strap bumping the throttle. If you do use a neck strap, it helps to get work out a procedure and make a habit of sticking to it. One idea that works well is to not attach the transmitter to the neck strap until you have the model on the flight line and ready to fly. Another method I have seen is to hold the transmitter with a thumb across the throttle stick to prevent it from being bumped.

Keep a Flight Log

Every pilot should get in the habit of keeping a detailed flight log. After each day of flying you should keep track of the day's events. Indicate where you flew, the date and time, the conditions, the number of flights. Take note of head-speed, if you're running glow or gas was the engine running lean or rich? After each inspection were there any signs of excessive or premature wear? Did anything loosen up? Did you make radio adjustments? How about blade pitch, did you make any changes? What were the pitch settings. Sometimes at the field you'll come across an item of maintenance that you know that you need to perform, but you'll forget about. Or at least you'll forget until that items fails on you as you're doing an emergency auto rotation. Don't let that happen to you, keep a log.

Headspeed ? why is it important

Headspeed can make a huge difference in how well your helicopter flies or whether or not you'll be able to do the hot 3D maneuvers you want to perform. For the most part the higher the headspeed, the more responsive your helicopter will be. Collective, cyclic, and tail rotor control will all be more responsive. That's why most 3D pilots favor a higher headspeed. Those looking for a less responsive, more controllable helicopter should reduce headspeed. A lower headspeed will make the collective, cyclic, and tail rotor less responsive. This is good for beginners and those who want precise hovering. Higher Headspeed = More precise control Lower Headspeed = Easier to control

Belt Drive Fishing

On a heli with a belt-driven tail rotor, it can sometimes be tricky to get the belt all the way through the boom. Save yourself a few minutes by simply grabbing some twine or kite string to help feed the belt. 1) Drop the string through the boom, and then loop the string around the belt. 2) You can either tie the string to the belt or drop the string back through the boom. 3) Once you've got a hold of both ends of the string, simply pull the belt through the boom and you're done. Simple!