V120D02S Modifications, Upgrades, custom parts, builds


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#1 - Index - First page of this build log:

#2 - BenMLee / Microline Hobbies Slipper clutch install/review

#3 - Bob's Slipper Clutch Install/ Review

#4 - KDBB 130X Main Blades = Upgrade

#5 - V120D02S - Xtreme Skids & tail Fin Weight Shaving

#6 - invert tail boom (by iflyrvs1)

#7 - Sheer Pin - 22 AWG Copper solid conductor

#8 - Metal Canopy Pin Upgrade / Servo Saver Mod

#9 - Servo gear Replacement/ Repair

#10 - Bearing care and maintenance

EXTERNAL LINKS:

#1 - Walkera V120D02S V2 Review - Pictures, Videos, Flight Times, Thrust, TA 915 Motor (by Tom Z)

#2 - Turbo Ace 915 with the XP-15A-2 ESC Review and KDBB Blades Review (by Tom Z)


More to come later. I'm just getting started with some of the data i've posted already in the V120 thread. I simply moved it here. There will be more to come including info on sheer pins, servo gear repair/replacement, canopy mounting, and more. I would also like to collect all of the files and documents pertaining to printing your own canopies and get them all together here, or somewhere else i can link to.

The images and information found in this build log is that of my own experience. It should be used as a reference point only. You should check your work carefully and against other sources for accuracy. In other words do your own research. Also, you should always use proper safety procedures. I will not be responsible if you experience any damages or injury by following this information.

BenMLee / Microline Hobbies Slipper clutch install/review


First Impressions:
This thing is awesome. Some could say over engineered too! But it's not! It's taken into consideration all of the problems that have plagued my v120d02s's tail box since day one! The shipping was quick and the product is QUALITY!. The "B" Gear appears to be CNC aluminum and very nice. The rotor hub for the tail shaft seems to be very high quality CNC or milled aluminum or metal anyway. I'm not sure about the tail shaft, but it would be nice to think it's hardened and tempered too, but I'm pretty sure it's not. There is no evidence or discoloring indicating a quenching process. Though it probably is still made out of a higher grade alloy than Walkera uses. I'm kind of interested to find out actually. The one thing anyone installing this clutch MUST BE CAREFUL OF!!! Don't loose your parts! They are damn near microscopic, especially the shaft pin. I installed mine over a magnetic tray.

Installation thoughts:
Installation notes and tips will follow in the picture comments below!

The installation was more involved than Bob's slipper clutch. After using bob's clutch since around March or April. I have to say his design worked! It was easy to install and simple yet functional. This new clutch by Benmlee is much more involved with installation because you have to remove the rear bearing and gear. I also had to remove the main gear and open up the bottom to access the whole tail boom for my convenience. But over all installation was really very easy.


After Installation, pre-flight analysis:
The whole design is much improved over Bob's clutch for the simple fact that it takes more of the over all helicopter's design flaws into account and tried to correct them. Of course you pay extra for these corrections too. The gear mesh was never right on this tail box and Benmlee knew it too. So he added a bearing shim to the package to fix the gear mesh. There is no longer a 0.5-1mm gap that my tail rotor can just wiggle free between the gear teeth. Nice and tight now. The step bearings that hold the tail shaft in place in the tail box on this helicopter, with or without Bob's slipper clutch installed, are a source of vibration and problems on this heli too. This Benmlee's slipper clutch take this into account as well and the design is made so that the whole shaft and bearing assembly become one rigid piece. The bearings are held securely and can no longer wobble. The pressure from the clutch secures the inner race of the bearings to the shaft so they can no longer slip free of the shaft causing intermittent vibrations. The only problem with this design is that over tightening the clutch will cause you some grief. Especially in a crash. But the same could be said about bob's clutch too, i suppose. Both are good.


Flight test:
Here is a newer video of me flying with the clutch. It works well.

V120D02S-Pro - 3D with no wind (3 min 29 sec)

Bob's Slipper Clutch Install/ Review


Bob's slipper clutch was the first one I ever used. It lasted me, easily, 6 months or more. It didn't break or bend the tail shaft until one of my bearings went bad and caused the shaft to sheer. But, Like many other people. I used his clutch and it worked perfectly the whole time without ever having to readjust or fuss with it. He has a large following of buyers for his slipper clutch and they simply work. They work well too. They may not be as engineered as the Microline Hobbies clutch. But it serves it's purpose 100% and does not cost as much either. Some people complained of bent shafts on the Microline hobbies clutch and prefer to stick with Bob's clutch. I find both do the job just fine. Bob's clutch is a little bit easier to install but you may have to fuss with your rudder configuration a little bit, and alter the setup from stock. If you follow his instructions you shouldn't have any problem. The instructions below are based on how I installed my slipper clutch and are here just for reference.



Okay, my installation notes will be attached to the pictures below:

KDBB 130X Main Blades = Upgrade




The KDBB 130X main blades are a upgrade in performance for the V120D02S. Though it may come with a trade off. Either because of their light weight or flexibility, They tend to be a little bit less stable than the stock blades. Especially in the wind. If you have your gyro turned up, you may need to turn it down for these blades. You will likely also have to adjust the cyclic ext. But maybe not. Some of these things are preference. At first i also added a "Expo" curve into my pitch curve to nullify some of the rotor's pitch authority. Since i run a Turbo Ace 215 with a 10T pinion. But i currently use a linear curve again. All i can say is these blades are a performance upgrade and you may need to tune the heli a little bit to get it flying stable again. My main problem was "wobbles" or servo oscillation in FFF, in the wind, or especially if the winds are blowing strong.


Though don't attempt to install the 130X tail blades. The root is too thick and it is not a direct fit. They are also smaller and would provide a worse tail hold over the stock blades. You can force fit them, but it will cause a bow, or U shape on the tracking path of the tail blades.

(Photo courtesy of flint723)



The KDBB 130X tail blades, force fitted. Notice the bent arching bow shape to the rotor.




Below are more photos of the blades fitted on the V120D02S and V120D05CS08. Many people asked me about my main blade holders when i first posted this. They are made by micro heli for 250 class helicopters.

V120D02S - Xtreme Skids & tail Fin Weight Shaving


After someone pointed out to me how heavy the extreme skids actually are. I decided it was time to trim some fat. So i removed the side rails that usually would guard the main gear. I also removed the rubber dampers i had on the skids and removed the metal skid pipes. I replaced them with CF rods and used a small piece of shrink wrap to hold the CF rods in place. Because vibes were moving them around, since they don't fit tightly. Over all, by doing this i was able to shave them down to 5.6g. Thats approximately 2.2g lighter on the skids.





Ej189 had a mod where he removed the tail vertical fin and replaced it with a CF rod to make the tail lighter and allow the tail rotor air to pass better. I didn't want to glue or fuss with a CF rod, even though it will probably be much lighter. It seems much less durable and easier to be torn off or not perform it's main function. Protect the tail rotor on landings. So i decided to bust out my respirator, full face mask, and Dremel. I cut my existing 3mm CF tail fin. 3MM is plenty strong to stand as a single structure. So the whole tail shape is not needed. (see pictures below)


For those who do not have the safety equipment or tools to cut your own tail fin, like i did there is a solution available for purchase. Of course I'd be happy to cut fins for profit too






I was browsing around and found these @ clubheli.com:

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I have turned the tail upside down and turned the blade holders around to put the servo rod on the bottom. Notice the screw heads on the blade holders are facing the heli. I put Bobs slipper clutch on and did the servo saver mod. I simply cut the servo arms with an exacto knife and it has worked perfect. I think you have tighened the arm too tight if they dont slip in a crash. I am flying mine upside down a lot and i crash once in a while but not too often. I have yet to lose a servo strip any gears or trash the servo rod and rocker since i did all these mods. This thing can really take a hit, About the only thing i lose now is the canopy and skids and i just tape it back together and keep going.

Originally Posted by iflyrvs1

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I have turned the tail upside down and turned the blade holders around to put the servo rod on the bottom. Notice the screw heads on the blade holders are facing the heli. I put Bobs slipper clutch on and did the servo saver mod. I simply cut the servo arms with an exacto knife and it has worked perfect. I think you have tighened the arm too tight if they dont slip in a crash. I am flying mine upside down a lot and i crash once in a while but not too often. I have yet to lose a servo strip any gears or trash the servo rod and rocker since i did all these mods. This thing can really take a hit, About the only thing i lose now is the canopy and skids and i just tape it back together and keep going.

Does it matter if the tail rotor is moved to the left side from the original right side?

Originally Posted by pshkong

Does it matter if the tail rotor is moved to the left side from the original right side?

NO I just take the whole tail boom off and turn it upside down and that puts the blades and tail rotor on the left side. I have been flying mine like this since the beginning and i can tell no difference in how they fly. Mike

Originally Posted by iflyrvs1

NO I just take the whole tail boom off and turn it upside down and that puts the blades and tail rotor on the left side. I have been flying mine like this since the beginning and i can tell no difference in how they fly. Mike

You will need to turn the tail holder around and counterink the holes on the opposite side so the screws will fit propery. Mike

Sheer Pin - 22 AWG Copper solid conductor


While having a thicker copper wire would be better. Say, 19 AWG or 0.9mm diameter copper wire would probably work the best. But they do no make 19 gauge wire in the USA. So i have been using 22 gauge solid copper wire. I happened to have some laying around so i just stripped the PVC jacket off a length of it and coiled it up. This is what i use to repair my V120D02S all the time:




In the above picture is a 0.9mm hex key a sewing pin and of course my coil of 22 AWG copper solid conductor. Since i use the Xtreme skids, often for a repair, i don't even need to remove the skids. This sheer pin mod, combined with a slipper clutch. I almost never need to replace main gears or receive any damage to the rest of the heli. Once you remove the stock pin. You can slip the copper wire though and bend it in opposite directions. Though every once in a while i like to drip some CA down the copper wire into the main gear holes. Then keep turning the copper wire so it can't become glued in place. What this does is make the pin's hole narrower. Because with a wide hole and narrow pin. In a crash, sometimes instead of "sheering" the pin. It will just suck both sides of the pin into the holes and wrap them around the shaft INSIDE the main gear. Making the gear fairly hard to remove and also, possibly eventually damaging the main gear's center hub. So using a little CA to narrow the hole keeps the pin sheering properly. I only do it every once in a great while. If you manage to stop turning the copper wire for a second and the CA cures it inside the hole, you will have a hell of a time removing it though. Just FYI.


Here is what the copper sheer pin looks like installed:





Below is a link to the sheer pin info pertaining to the V120D05, in my D05 build log:
http://www.rcgroups.com/forums/showt...2#post22800686

Metal Canopy Pin Upgrade / Servo Saver Mod

I use a small size paperclip and straighten it out. The particular size paperclip i am using is just a bit too narrow. So i typically bend it a little bit in a "bow" shape so that it wedges in there a little bit. The hole in the center and the "bow" shape pressed against each servo. The arching pressure will hold the paper clip from sliding back and forth, for the most part. It can stay straight too. It will honestly end up getting all bent in different shapes anyway. I also use some needle nose pliers to bend little hooks on the ends so the canopy grommets cannot just slip off. Since this heli's battery is belly loaded, there is hardly ever reason to remove the canopy. Just be careful installing it with the "hooks" so you don't ruin the rubber grommet with the sharp edges.

I got sick and tired of ordering new canopies just because my canopy pin broke. Then when i made the switch to Xtreme canopies, they don't come with a canopy pin. Sure you could buy CF rods and cut them to size. But this was easier and came with an unintentional side effect that ended up being a big benefit, IMO. It's also a servo saver mod, of sorts. In a crash the metal canopy pin, being narrow to begin with, makes the pitch and aileron servos a little bit loose in their brackets. Just enough that they can pop out in a crash! Saving the gears and servos from damage. If the force is great enough the metal canopy pin will bend and the servos will still pop out. Leaving only the Elevator servo to worry about. I also leave the elevator servo bracket's single screw next to the motor just a turn or so loose. So that it's not completely tight and the servo has some wiggle room in a crash. Though honestly since installing the Nine Eagles 318A servo gears from OOmodel. I have not stripped any servo gears. More on that in the next section though.

Servo gear Replacement/ Repair


Okay, so working on the servos of this helicopter will undoubtedly become something that you will at some point have to do. Replacing the whole servo is quite expensive. Walkera, at one point, or so i've heard. Released servo gear replacements for their V120 class servos. But you won't find them anywhere, thats for sure. Lucky for us, Nine Eagles 318A servo gears are a direct fit for the servos. However the main exposed spline for the servo horn is a few mm longer than the stock spline. This throws off the swash linkage geometry a little bit. But you shouldn't notice any difference in performance or behavior. OOmodel.com sells these 318A servo gears as replacements for the V120D02S. Also Helipal.com sells them too but are a little bit more expensive. Helipal.com also re brands them and calls them "airy gears". I have purchased gears from both vendors and they are identical.


So here is what the servo will look like with the new gears installed. I don't have any original stock gears or servos to show. So i am going to use a photo courtesy of RCG member lasakro to show the stock compared to the new replacement gears.



Stock V120D02S Servo gears (Courtesy of lasakro)




V120D02S Servo with Nine Eagles 318A servo gears installed:


When installing the new replacement gears, they will be "dry". While with plastic gears, it's not exactly a requirement to lube them. You may want to add a plastic safe grease to the servo gears, so they will wear in a bit easier and run smoother. But you don't want to add a lot. Having excess grease in the gear box will cause extra friction and stress that could burn the motor out sooner. Just a little on the surface of the teeth is fine. any excess gobs can be wiped away. I would think that any plastic safe grease should be fine. I personally use a silicone grease that i had left over from my cable tv days. Since it is rubber & plastic safe. Clear Lithium grease is also a option. I would think that tri-flow clear synthetic grease would be okay on plastics as well. Other plastic safe grease types would include Teflon or PTFE grease or maybe even barium grease, but thats probably not something you will have just laying around. I would stick with either Silicone or clear Lithium. The Tri-flow clear synthetic grease should also be fine.

It's worthy to note that sometimes when you strip a gear, full replacement is not always needed. Because sometimes only 1/2 of the actual gear is used for full throw of the servo. So you can sometimes just open up the servo. Power it up and move the servo from one extreme to the other. Watching where the broken teeth are, you can often rotate that broken gear and place the broken teeth on the side that does not get used or mesh with any other gears. Though for the cost of gear sets. Full replacement is not a bad idea either.


I will give some assembly notes in the photos below on how to arrange the gears in the servo. But the pictures are mostly self explained.

Bearing care and maintenance

Okay, here is a simple guide to oiling and maintaining your V120D02s's bearings. You do not want to over oil the bearings, because it can get messy. I usually let the oil wick into the bearing and then wipe away the excess with a swab or paper towel. As you might see in some of my photos. It's very sandy here and it sticks all over the heli. The oil does not make the cleanest heli in the world. But the bearings will run much smoother. Otherwise friction will build in the bearings and the ESC and motor will run hotter because of it. Between the friction and additional heat, performance and flight times will eventually be severely hampered.

I am not going to give a specific amount to oil your bearings. I am neglectful with mine quite often and the heli's friction remains very low. But keep this in mind. The tail shaft spins at the highest rpm. So the torque tube bearings and the tail bearings have the highest load on them. Technically, they are the most likely to eject their oil quickly and need sooner lubing. So that being said, you should try to oil all of your bearings in the "drive train" some where between every 5-12 flights. Something like that. You don't need to oil them if they are obviously wet still. You don't want oil pooling up under the bearing or anything. Between the two main shaft bearings tends to be very oily and greasy, so you might want to pull the shaft out and clean in there once in a while too. I personally don't oil my torque tube bearings very often. I'm not even sure how much or if any oil actually gets in there. But you should still check the bearings for free movement and not being gritty as often as possible. Over oiling can cause lots of ejection too. You want to be careful and oil as little as possible, quantity wise. A tiny little dab goes in deeper than you think. a regular drop could be too much in some cases and will just be messy. You can wipe the excess away with a swab but soaking the bearings inside will make a mess too. Some bearings could go as much as 20 flights and still be pretty well lubricated. I recently let mine go about 25 and though most of the bearings were pretty dry. They still had some grease in them keeping things smooth. If you live/fly, like i do, in a place with lots of sand. You might want to oil some places less and swab away as much excess as possible. The tail can get messy and you really should use something to take off and land on, so it's not right in the sand.

One last thing. The only bearings in this guide i did not cover are the blade grip bearings. Which should be included in this too... However, i don't oil mine. I check the bearings once in awhile. But if they go bad i'd rather just replace them. I think i've only had to replace the main blade bearings once. So they don't really "need" to be oiled. But every once in a while might be a good idea to give them a drop.


Just for reference. This is the Scorpion oil kit i use:

Thx. Very thorough and informative!