Walkera Dragonfly 4 -
spares, repairs & tips
The Walkera Dragonfly 4 electric rc helicopter is one of many Fixed Pitch (FP) radio controlled helicopters on the market these days, meant for the newbie model helicopter pilot.
Such helis are sold as RTF (Ready To Fly) models and while this is true in most respects, trying to fly the helicopter straight out the box without going over it and checking a few things over will almost certainly result in a bad flying session - and probably put you off RTF electric helicopters for life!
Knowing the popularity of the DF4, I've written some guidelines based on my own Dragonfly 4 to help you have a smoother flying experience with your Fixed Pitch electric rc helicopter.
This page offers additional info on Dragonfly 4 spares, repairs and tips...
Get 'spared up'!
Electric FP helis like the Dragonfly 4 are remarkably robust considering how 'spindly' they are, but successive heavy landings can weaken things - and of course an outright crash can do serious damage in one go!
If you've just bought such an rc helicopter and it's your first, or you are considering buying one in the near future, take this advice; buy some spare parts right away/with the helicopter!
If you've never flown a multi-channel rc helicopter before then the chances are that you will break something sooner or later, and the following list gives examples of likely breakages that you might encounter.
The list comes from my personal experience of learning to fly the Walkera Dragonfly 4...
- Even with training skids fitted, the rotor blades can strike table legs or walls if you get into trouble, and if this happens there's a good chance that the tip of the blade will snap off if the impact is severe enough.
- The landing gear is strong, but the joints where the legs meet the skids are weak, or get weak after being bumped down onto the ground enough times.
- The front cross-member of the landing gear assembly can snap at its narrowest point if the helicopter goes in nose-first, pushing all the battery pack weight against it.
- The flybar can splinter in a bad crash (and snap of course, but that definitely means a straight replacement - not a repair!
- The tail motor can burn out, although I have heat sinks fitted and I haven't yet suffered this problem.
Fortunately, the availability of Dragonfly 4 spares is very good for anyone in a country with a good, fast postal service.
Mine isn't, and so buying spare parts for the helicopter involves a frustratingly long wait - for this reason my Dragonfly 4 has been 'patched up' numerous times to get it flying again until broken parts can be replaced with new!
The Walkera Dragonfly 4 spares
Shown below is the official 'spares chart' that comes with the helicopter. Click on it to get a larger version in PDF (Adobe Reader needed), but please bear in mind this is for reference only - don't try ordering anything from me via the contact page!
The purpose of showing the chart is only to let you see what's available, and which part number is attached to which spare part.
My Dragonfly 4 repairs
As I mentioned earlier, our local postal service isn't too impressive. In the past I have purchased an item from abroad and waited three weeks before seeing anything!
When I got my Dragonfly 4, I had some spare rotor blades added to the order. Stupidly this was all, and I soon broke the landing gear front cross-member and landing skid assembly.
So, determined not to be grounded until replacement parts arrived, I carried out some emergency repairs to the helicopter so that I could get flying again.
I'm not recommending that you do the same, but should you be in a situation where you think that a temporary repair will get you out of trouble, below are some examples of what I've done, to perhaps offer some inspiration...
Flying a helicopter with broken parts is stupid and potentially dangerous. I'm confident about making such repairs, but if you have any doubt about your own practical abilities, wait for the spares to arrive!
Rotor blades - do not try and repair them! I did superglue a broken blade back together but I did not fly with it - it was only a test to see how strong the joint would be.
If you snap a blade, replace it - don't repair it!
The landing gear - this gave way at the joints of the skid and legs. Initially I epoxied the joints but this soon gave way again after hard landings. For my next repair attempt I used epoxy and fine thread wound around the joint to bind the two parts together. This was OK for a while but, again, it didn't last too long.
The most successful repair has been made using the brass inside of electrical terminal block connector. It's ugly, but it works!
The hole inside the brass connector was slightly smaller than the skid 'stem' of the joint, but I overcame this by repeatedly heating the brass and (with pliers) twisting it down over the stem. When it's heated enough, the brass melts the stem as it goes, ensuring the perfect fit!
Also, as an unforeseen added bonus, the melted plastic stem binds to the inside of the brass as it cools.
I made sure that the brass was pushed down onto the skid enough for the broken stem to show behind the screw hole of the connector.
Next, I stripped some 2.5mm* electrical wire (*this is a UK size reference) and slid the plastic insulation over the leg - 2.5mm outer insulation happens to be a perfect fit over the leg and into the brass connector.
The final step was to insert the leg into the connector and tighten the two grub screws into their holes. The lower screw held the stem of the skid, while the upper screw gripped the plastic 2.5mm insulation around the leg.
Above left, the 'melted on' brass connector. Middle, the legs & skid. Right, the final result.
I repeated this on all 4 joints, even though only 2 were broken. I did this because of the balance issue - the brass connectors of course add weight and in fact they are relatively heavy for their size.
As a final back-up, I stuck narrow strips of duct tape down one side of the brass, around the bottom of the skid and up the other side of the brass.
To date, it's held together very well - despite more bumpy landings! Obviously it needs to be replaced with the lighter original set, but it's a fair solution in desparate times!
Landing gear front cross-member - this was a fairly straightforward repair. It broke at its narrowest point, very close to the point where the front right leg goes through.
I superglued the cross-member together as it was a very clean break. Having done that, I laid it on some 1/64" modeling ply and drew round it - I did this twice, rotating the member 90 degrees on the ply for the second one.
This gave me two outlines of the cross-member on the ply, with perpendicular grain directions.
I cut out the templates with a craft knife and epoxied them to the member - not one each side but both of them on the front, one on top of the other. So far it hasn't broken!
The flybar - this also applies to the landing legs and skids, if they split or splinter.
Repairing the flybar isn't a sensible option really, but this repair did get me airborne again without problem. I certainly would not try and repair a snapped flybar - only a splintered one, where the carbon fiber has come away in strands on the surface.
To make good this kind of injury, wrap electrical tape around the damaged area and then put on heat-shrink tubing to cover the tape. Carefully shrink the tubing evenly and this will harden as it cools.
The purpose of the electrical tape is to give the heat-shrink tubing something to adhere to - it doesn't like sticking to carbon fiber.
If you are repairing a splintered flybar, you obviously need to put the same amount of tape and tubing on both sides, and in the same positions. You also need to rebalance the flybar afterwards.
Once again, I did this only as a temporary repair.
Other tips
This section will offer tips resulting from things that I've found out about my Walkera Dragonfly 4.
Hopefully they will help you to overcome problems that you might be experiencing with your FP electric rc helicopter. I'll add to the list as I discover more...
| Problem | Image | Remedy |
| Tail motor screws - periodically check the 2 mounting screws. They can work loose, resulting in the tail motor disengaging from the rotor sprocket. |  | Tighten them! |
| Tail motor casing - the small tag on the rear/top of the motor casing can lift up. The motor innards creep out and the motor cog does not engage properly with the rotor sprocket. This isn't obvious at first glance, you'll notice it when the helicopter yaws badly to the left - too much for you to correct. |  | Bend the tag back down - you'll need a very small flat bladed screwdriver or similar. A drop of cyno on the black plastic before you push it back in helps a bit. |
| Servos - both servos clip into position. They are a snug fit but they can 'pop out' of their clips and so don't deliver an accurate amount of movement to the swash plate. |  | Place your thumb on one servo and index finger on the other - push together firmly until your hear a definite 'click'. Check top and bottom clips. |
| Battery lead - as supplied, the lead exits out to the side and backwards from the front of the pack. This makes it harder to slide the pack into the cage, and you risk damaging the lead in the process. |  | Very carefully slice the plastic casing just enough so that the lead can exit directly away from the end of the pack, without going out to the side first. This makes inserting the pack into the cage a lot easier! |
| Canopy - this isn't a problem, but if you're as paranoid as me about things overheating, cutting out the 2 flats on each side of the canopy might help. |  | I heated a modeling knife so it melts & cuts at the same time - it goes through the plastic with ease, but you still need a steady hand! |
| Throttle rachet - this is just something that I've done to get smoother motor response, because the ESC is very sensitive to the slightest movement of the tx stick. To remove the rachet on the motor stick isn't a big job, but taking apart the tx will almost definitely invalidate any product guarantee, so beware! Also beware that removing the ratchet obviously makes the stick more easily moved (that's the idea!) - remember this when you're switching on the heli, as the stick won't stay in the shut position if it's accidentally knocked even very gently. |  | Unscrew the 4 screws in each corner of the back of the tx. A magnetized screwdriver is a good option, the screws are small headed 'philips'. Very carefully and slowly prise apart the two halves of the tx body - don't open it completely or you will break wires and solder joints! The 3rd photo shows the metal rachet (Mode2 tx) in its proper position, the 4th photo shows the ratchet moved across to the right (easy, by hand) to clear the throttle gimble. Join the two halves of the tx back together, starting at the handle. Make sure that the 4 pins and corresponding holes (arrowed, last photo) slide together but be careful, the pins bend and/or break easily. Once the handle is sorted and the body is together, replace the four screws. |
Related pages
Rotor blade balancing - how to balance your blades if you don't have a balancing tool.
Rotor blade tracking - how to get the blades tracking correctly.
Flybar balance and paddle pitch - more ways to stop vibration.
Walkera Dragonfly 4 rc helicopter spares, repairs & tips - useful tips for the DF4, based on my personal experience.
Your first hops - tips & advice for to get airborne.
Main frame replacement - guidelines for the worst job of them all!
DF4 battery upgrade - upgrading to a lipo pack
Index - to all Walkera Dragonfly 4 related pages.
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