I was so impressed with the TREX 700 gasser conversion that I decided to give the 600 a try. The kit arrived with everything as described on the Helibug website.
Before getting started with the build, you will need a few prerequisites. If you already have a TREX 700 then you might have some of these spare parts already lying around.
- Lynx TREX 700 Upgrade Clutch LX0016 $39.50
- After running both the stock and QuickUK clutches, this clutch is simply the best. The quality is amazing and I highly recommend it over the other two.
- Lynx Gasser Upgrade Liner LX0052 $4.35
- This comes in several versions but the gasser version is a little thicker and is recommended
- You cannot run this with the stock or QuickUK clutch upgrades. Only get this if you are also getting the Lynx upgrade clutch. The Lynx clutch is slightly smaller in diameter. I was barely able to even force the stock and QuickUK clutches into the bell once this liner was installed.
- Tygon/Gas Fuel Tubing.
- I purchased 5 feet of clear fuel line from my local Ace Hardware. $2.50 @ .50 / ft
- 1/8” Fuel Filter / clunk to go inside fuel tank.
- For simplicity, price and availability, I prefer to purchase the MaxPower filter for chainsaws and trimmers from my local auto parts store. AdvanceAutoParts and Autozone both carry them and it helps support your local economy. You can also purchase these exact filters for about $1 more online at Daves Discount Motor. $3.29
- Align TREX 700 Flange Bearings HN7067 $8.99
- Align TREX 600 One Way Bearing H60021 $7.99
- Align TREX 700 Clutch Bell HN7038 $17.99
- Align TREX 700 Start Shaft Set HN7036 $8.99
- Optional Align TREX 600 Frame Mounting Bolts HN6104 $3.99
- Optional Align TREX 700 Servo Linkage Rods (Linkage rod(E)) HN7064 for the Throttle $7.99
- Align TREX 700 MOD1 Main Gear HN7019A $16.99
- AT600-MGC KDE Direct Main Gear Auto Hub AT600-MGC $20.99
It really is true that you always need to use the right tools for the job.
- MIP Thorp Hex Drivers 1.5mm, 2mm, 2.5mm $14 each w/ free shipping. http://www.rjrcooltools.com/shop_it...m?subcat_ID=117. These drivers are the best ever. You will never ruin another tip again. They are pricy, but go ahead and buy them now or you will be sorry. I have build 6 helicopters without them and have ruined countless hex heads and stripped out even more screws. I just purchased and used these for the very first time on this build and am absolutely amazed at what I have been missing out on. Don’t think about it, just go buy them!
- Small set of 2 jaw bearing pullers. A 4”-6” set will do. These are an absolute must for any heli builder. Without them you will never be able to remove a hub from an engine, a clutch from a hub, or even install some bearings. Yes, bearing pullers can also double as bearing installers as you will see in this build. You would be amazed at just how often these come in handy.
- Blue thread lock and Green High Temp/Bearing thread lock
- High Temp Gold RTV Gasket Maker for sealing your exhaust.
- Large channel lock pliers.
- Caliper. I use a Kobal digital purchased from my local Lowes. It is actually a very nice caliper and comes with a handy storage case.
The kit is made from some very thick G10 and is of the same high quality I have come to expect from Helibug. All of the cuts are perfect and nothing was out of the ordinary.
- This is the stack I started from. The bucket in the background is my disassembled TREX 600. If you are like me and are converting an existing build, then step one will be to break your heli down into a bucket of parts and bolts.
I was originally going to use the KDE Direct 700 main gear but later discovered it was too big. Even though it is pictured here, do not use it. You must use the Align Mod 1 gear instead. The Helibug website says you can use microheli, but I have had nothing but bad luck with microheli. I have stripped both microheli and align gears and prefer to strip cheaper gears when given a choice. I had run these Align Mod 1 gears on my 700 conversion and eventually stripped one tooth. Because this is smaller and the stresses should be less, I suspect this gear will hold up fine for this heli. Only time and testing will tell.
Assemble the individual component groups.
- Sand the frames. Like all new heli builds, it is recommended to sand all the sharp edges off the side frames. For the first time ever, I have actually skipped this step. Already knowing how I run my 600 wires, there are only a few places that need to be sanded and I dealt with them after the build was complete. If you prefer not to have to worry about cutting yourself on the frames and just want to be safe, then start sanding.
- Go ahead and get the major components built so you don’t have to get side tracked during the build. I started off by removing the old clutch liner and installing the Lynx Gasser upgrade liner. Be sure to use sand paper and get all the old glue off the bell.[LIST]
- If you have never changed out a clutch liner, it is super simple. Just take a screwdriver and pry up the old liner and rip it out with needle nose pliers. Take some sandpaper and scrub out all the old glue and left over black liner residue.
- Using some 5 minute epoxy spread a very thin amount all around the bell. I repeat, spread a very thin amount. It should be transparent. You do not want any excess glue squeezing out and gumming things up. I have been over zealous with the glue in the past and it caused the clutch to engage sooner than desired and took a while to wear off. It eventually cleaned itself up, but it’s better to just get it right from the beginning.
- Don’t take the logical approach and try to install the liner from end to end. Start by connecting the ends and then working the liner into the bell while leaving a bow as pictured. Once you get it looking like the picture, just push that bow up into the bell and everything will slip right into place and tighten up. That’s it for the liner.
[*]Build the clutch stack.
This is done exactly as defined in the manual with the exception of one flange bearing, and you are using a 700 bell and start shaft. When installing the start shaft, simply place the flange bearing between the block and starter coupling to take up the extra space created by using the 700 shaft in a 600 block.
[*]Assemble the fuel tank.
Having flown planes, nitro and gassers, this step was natural. If you have never assembled your own Dubro fuel tank then this will be a new experience for you. Copper tubing is very sharp and will cut into your fuel tubing like a razor. Make absolutely sure you round off all the edges before you call this task complete. The tank is pre configured for 2 lines, and comes with 2 really long pieces of copper tubing. I prefer a 3 line tank. 1 Line for the fuel output, 1 for the vent, and 1 as a return from the primer on the carburetor.
- Be sure to use the red gasser rubber stopper supplied by Helibug. Toss the stock black one. It is used for nitro only.
- Prepare the vent line by take a piece of tubing and heat it with a heat gun or lighter. Slowly bend it up as shown in the picture. You will want to make sure this tube arcs up and almost touches the very top of the tank when installed. It is trial and error and will require a little tweaking until you get it perfect.
- Cut the other piece of tubing in half and round off the edges. Install one in the precut hole. Using a drill bit, punch out the 3rd hole and install the final piece of tubing.
- Install your Max Power, or other clunk filter of choice, using some flexible tubing. I use Hayes neoprene tubing for all my clunk lines, nitro and gasser.
- Install some Velcro to the top of the fuel tank so it can be affixed to the frame in a later step. I made use of some scraps, so I apologize for the mess.
[*]Install the One Way bearing into the KDE Adapter Hub
You will really need a set of small bearing pullers to do this cleanly. Without the bearing pullers, I can only assume I would be trying to hammer this bearing into the hub over a vice. This would most likely damage the bearing, housing, or both. Apply some green thread locker to the bearing. Heat the assembly using a heat gun. Use a washer and screw to convert the bearing puller into a bearing pusher. Slowly crank the puller until the bearing is pushed all the way down into the hub. If you have the hub sufficiently heated, the bearing will slide in like butter. It is very smooth and requires very little effort. If you have to apply a lot of force then you didn’t get the hub hot enough.
- IMPORTANT NOTE! The KDE instructions suggest leaving 1mm of the bearing exposed on both sides. That does not work for this build. Compress the bearing all the way down. Also, as per the instructions, make sure you install the bearing with the etched text down.
- Install the hub into the main gear. Go ahead and complete the rest of the gear assembly per the normal instructions and set it aside for later.
[*]Secure the clutch and hub to the engine.
Helibug supplies a button head screw to secure the hub to the engine. I am not a big fan of using screws on the hub and chose to go with a bolt and lock washer. I have used a screw like this before and it worked flawlessly. I just happen to have a bolt and washer and chose to use it. The biggest concern, for me, is if you were to somehow strip the head of that screw you will have a hard time getting it off. A hex head bolt is fool proof.
In this photo I am using a pair of channel locks to hold the hub in place. Though it might appear I am using the pliers to grip the hub, I am actually not applying any pressure at all. The 2 tabs for the clutch bolts are spaced perfectly to ram against the tips of the pliers. I am applying just enough pressure to keep those tabs against the pliers which keeps the hub from spinning. When done, there is not a scratch on the hub because no force was actually applied directly to the aluminum. Without these large pliers, I would have needed a piston stopper or something to secure the shaft. Since I don’t have one, this would have been a very difficult step to complete. I have used these pliers for this exact same task on every nitro and gasser build I have ever done. I have never owned a piston or crank stop tool.
[*]Assemble the engine base plate, motor mounts, and skids.
I like to build up my foundation first. This makes for a convenient building platform going forward.
- Note: Affix the frame mounting blocks to the G10 motor mount plates BEFORE you install the plates on the engine. On my first attempt, I installed the plates and then attempted to install the blocks. There just isn’t enough space, so I suggest installing the blocks to the plates and then the plates to the engine.
- Install the skids and the 4 frame mounting blocks used to anchor the main frames.
[*]Build the front canopy mount.
Because the frame is a little taller, you cannot secure the canopy to the front skids like you do in stock form. You must install a frame support in the new mounting position above the front skids. The no fuss method is to use the HN6104 Frame Bolts from the prerequisites list. I indicated these bolts as being optional in the prerequisites because you can use spare parts from other things here. I actually forgot I had these bolts and started off using spare parts from my TREX 700. I did come back afterwards and install the 600 frame bolts because they are a perfect fit, but here is what I did in case you have spare parts and want to save a couple bucks.
- Take a spacer from a TREX 700 fan housing and cut it down to fit.
- or just install a HN6104 TREX 600 frame bolt and you’re done.
[*]Modify the canopy front mounting clip to work with this new mounting position.
In stock form, the clip is going to be opened up pretty wide. If you install the clip without any modifications, it will just pop right off with minimal effort. You must heat and mold the clip into a more closed position.
- This material is very strong and once molded into position it will not lose its new form. Using a heat gun, or other heat source, and a pair of pliers, heat and squeeze the clip into a closed position.
- Install the clip UPSIDE DOWN to the canopy. Yes, UPSIDE DOWN, INVERTED! Test your molded clip by snapping it into place.
- At first I was concerned this would not be sufficiently tight and might pop off in flight. It will not pop off and might actually be a too tight if you completely collapse the clip. You don’t want it so tight that you crack your canopy paint trying to pull the canopy off. You may need to reheat and open the clip up a little if you find it too difficult to take the canopy off. I felt mine was a bit too tight and had to go back and open it up just a little. I suggest not closing it completely off from the start and you might end up with a perfect fit without having to go back like I did.
- The front and rear mount holes are slotted for adjustment. You will want to position everything to best fit your canopy and hardware. I use QuickUK rear mounts and had no difficulty getting everything to line up. Hardware and canopies are all a little different but should all fit perfectly given the adjustability built into these frames.
[*]Epoxy the flange bearings for the bell cranks.
You may choose to do this at the very beginning before installing the frames. When I inserted the bearings there was the slightest amount of play. I doubt this could possible cause an issue, but I decided to hold off until now to install them so that I could do it while installing the bell cranks. This would ensure a perfect fit. Again, I am not sure they could possibly be off enough to cause trouble if you installed them separately; I just wanted to play it safe and go for perfection.
- Run a line of epoxy over the bearings and slide the bearing onto one side and then run the bell crank support rod through the frame. Epoxy the other bearing and slide it onto the rod and into the frame. Install the crank and secure it. This will crush the bearings into the frame and ensure they are perfectly positioned and will hold them in place till they dry.
[*]Secure the nose and start installing your electronics.
I completely covered the nose in the fuzzy loop side of the Velcro. Personally, I always install the hook Velcro to my components and the loop to the heli. Apply your standards here.
[*]Install the head, main gear, and hook up your servos to the swash.
Just follow the instructions in the manual. Your link lengths might be just a little different. I typically just use the manual as a point of reference anyway. Make sure you get your servo wheels and cranks at a perfect 90 degrees and adjust the links accordingly.
- Note: This is where the position of the one way in the KDE hub is crucial. If you didn’t get that bearing pushed all the way down then you might have gear mesh issues. The position of that bearing is going to have a direct impact on the vertical position of the main gear on the main pinion. If it is not vertically centered, adjust that bearing accordingly by reheating the assembly and pushing/pulling as needed.
I have a lot of different size rods lying around. If you don’t have spares and will be using a full size servo, then the rod defined in the prerequisites might work. Thread your 700 links onto the 72mm TREX 700 rod and get your linkage setup. I listed this as an optional part in the prerequisites because you might be using a different throttle arm on the engine and even a different wheel size on the servo. This length just happens to be the size I needed.
- Install the tail assembly and tail boom by following the stock instructions.
Align DS610 Cyclic Servos
Futaba 9245 Tail Servo
Futaba 9254 Throttle Servo
Spartan DS760 Gyro
Futaba GV-1 Governor w/ the Real Stator Gator Sensor
JR R921 Receiver
Align 2-in-1 Regulator
Align 1900 Lipo
Pennzoil 100% Synthetic Marine 2 Cycle Oil 40:1 mixtureFlight Review
Let me start by saying this is an absolute beast! Because I am using a G29, this thing might just be overpowered. I can't say it is unboggable because it is a gasser. But I can say it stops bogging at a really high head speed and continues to maintain the pop. It is nothing like the 700 conversion. You can stick bang this thing non stop and it never dies off. I was absolutely shocked. You will obviously not get these same results from a stock G240 and since I don't have that size engine to test, I can only comment on what I have.
I really wish I did get a video because you would be shocked.
I did not get a chance to shoot videos of the first flights because I wanted to get it all dialed in before I boring anyone with a bunch of hovering. I managed to get in about 4 tanks before disaster struck. The first couple of flights all went fine and were the usual trimming, tweaking and adjusting sessions. I finally got it all dialed in decided to fly a little harder and shoot some autos.Autos
This heli is clearly going to be heavier than the stock nitro version and the blade size simply does not allow for any hang time. Once you start your flare, that's just about it. There is really nothing left to soften the landing. I tried several times to get a good auto and on my final attempt I touched the tail. I hit it pretty hard and thought I heard a gear break. I did a pretty thorough visual inspection and didn't see anything wrong and proceeded to fly some more. This was about 1 1/2 tanks before disaster struck.Tail Authority
I was unable to get the tail to hold with the stock tail blades. Running the gyro gain up would eventually cause heavy wagging. No matter how high I ran up the gain, the tail simply wouldn't hold. I'm not talking about a minor or slight drift. I am talking a really good left turn that wouldn't let up as you punched out. Tictocs and rainbows were ugly. You would go in straigh and be 45+ degrees off almost instantly.
I completely solved this by installing TREX 700 105mm tail blades. It went from horrible to rock solid right off. I was finally getting somewhere.The Tail Gears Stripped
At this point I decided to put it through the paces. I probably should have eased into it a little slower, but no, I couldn't do something like that now could I? I started throwing it around as hard as I possibly could. I was so impressed by the ridiculous amount of power and the extreme performance I was seeing that I just wanted to see how hard I could push it. I hit it with non-stop piro flips and tictocs. During the piro flips, the tail let loose. I completely stripped the front torque tube drive gears on the crown sides.
Because I changed tail blades, and I touched the tail, I really have no way of knowing if:
- The tail drive gears can't handle the torque from the engine.
- The tail drive gears can't handle the torque added by the 105mm blades.
- I actually did damage the gears in the tail touch.
I guess I can be thankful to have been flying long enough to know all my orientations and be able to get myself out of a really bad situation. The tail broke loose while the heli was pointed straight up. It took a couple seconds after hitting throttle hold before it slowed down enough to try to gain control. It was a real blur. I finally got it leveled out a couple feet before hitting the ground. Remember what I noted aboive about it not autoing well? Even though the blades were spinning, there was only enough there to sloften the blow. It hit square on the skids.
So far I am only looking at about $60 in repairs. The blades actually survived. I am going to make the repairs and then do it all over again on video. Since I don't really know what went wrong, I am a little scared of it.Current Conclusion
If it can handle the power and this little mishap was due to my tail touch, then this heli is amazing. If the gears are simply not strong enough to handle the torque, then I can only reduce the power. After getting a taste of what it can do with a G29, I am not so sure I would be satisfied with a neutered alternative.
I should have it repaired early next week and will get some videos posted soon.Videos
This is the first real flight I was able to get after my tail mishap.
Watch at YouTube
After getting it trimmed out, this is the remainder of that flight.
Watch at YouTube