Building a Trex 450 Sport (Part One)

Builders log, What you need to get started:

I'm by no means an expert on RC helicopters, but I can provide you with some resources and answers to problems I ran into while building my Trex 450 Sport.

For starters let me tell you, the factory instruction manual is lacking to say the least (view a copy). You will have to do a lot more reading and watching of videos if you want to be successful at getting this bird into the air. Thankfully, there is a ton of information on the net to help.

The first place you will want to start gathering the info, besides here of course, is at Finless Bob's Helifreak Tech Room.
Bob White, otherwise known as Finless Bob has been building and flying RC helis for quite some time. Along with this he has been creating videos documenting all aspect of this hobby. His videos have helped many that otherwise would have fallen to the wayside with frustration. I'll refer to Bob's videos as we go.

My first step was getting everything together that I needed to build the Trex. The list below is what I purchased to build the Sport 450. Some of these items could be considered optional and I will let you know as we go of any ways I found to save money.

Parts:

Trex 450 Sport Super Combo Kit
Spectrum DX6i Transmitter
Spectrum AR6110e Receiver
Rhino 2250mAh 3S1P 30C Lipo Battery Pack
Deans or XT60 Connectors

I chose the super combo kit as it provided me with all the electrical components I needed expect the transmitter, receiver and battery. From all my research, it appears the Align servos and gyro that come with the kit may not be the best, but will work fine at getting me into the air and hovering. I figured that if need be, I could upgrade them later.

The Spectrum DX6i transmitter is another component while not the best, will serve just fine in getting me airborne. The next step up would have been a DX7 that has 7 channels, only 6 needed for the sport. It also allows you to store more model memories, not something I needed and the gimbals have a more solid feel. Again, I figured if I got into nitro helis where I needed the 7th channel, I could upgrade then and sell the DX6i to recoup some of the costs. At this point I've been using the DX6i with Phoenix flight simulator and I really like it. Don't think you can go wrong buying this transmitter.

For a receiver I chose the Spectrum AR6110e as it was recommended and used by a lot of sport pilots and with it's end pin configuration, I could mount it under the gyro tray keeping all my radio components away from motor components to avoid radio interference. Per the suggestion of Finless, I also purchased a separate battery box to power the receiver during setup so that I wouldn't have to use the speed control's built in BEC (battery elimination circuit) and the Rhino lipo thus avoiding accidental spin up of the motor while setting up the servos and head. This worked great and well worth the $5.19 I paid for it at Tower Hobbies. Besides the bat box, I also picked up some tracking tape that would be used during blade tracking and balancing.

Most of the major parts I got from Grand RC. They have great prices and give first time customers an additional 10% discount. They shipped my stuff on a Tuesday and I received it on Thursday. I was very pleased with their service. As for batteries, every thing I read and price forced me to try ordering direct from hobbyking.com in Hong Kong. While I'm all for buy American, none of this stuff is made in the USA and the money still leaves the country, even if you buy it from a US supplier. With battery prices 1/3 of any in the US, I couldn't resist giving HK a try and decided on the Rhino 2250mAh 3S1P 30C pack at $23.00 each. They carry cheaper but at the time these were in stock and I found nothing but good reviews of them. I was advised to pay the additional cost of EMS shipping so the delivery would not take forever. From order time to my door step it took 10 days and I would order from them again. Be advised these particular batteries came with XT60 type connectors, I decided to use this type connector on my speed control so that I would not have to change out those already installed on the batteries. I found XT60 connectors on e-bay as well as on the Hobby King website.

Tools Needed:

Soldering Iron
Solder and Flux
Hex Driver Set
Ball Link Pliers
Ball Link Sizing Tool
Swash Leveling Tool
Pitch Gauge
Flybar Lock
Metric Ruler
Dial Calipers
Needle Nose Pliers
Dremel Tools with Cutoff Wheel
Small Philips Head Screwdriver
Blade Balancer
Lipo Charger Balancer
Lipo charging Sack

The above list is what I used to build my sport. The manual says all you need is a pitch gauge and charger but I think you would have a hard time using just the few hex head keys and screw driver included with the kit.

For sure you want a set of hex drivers. Trying to assemble this heli with the supplied hex keys is possible, but the drivers really speed up the process. You will also be much less likely to strip a screw head and their long reach works well for trying to fish a screw into a tight place. I bought the Align set of 4 that includes these sizes, 1.5mm, 2.0mm, 2.5mm, and 3.0mm and they work very well. I understand that Thorp makes really nice drivers but at $10 to $15 each, they are out of my budget.

Get a pair of ball link pliers. It would get real old trying to snap and unsnap links with your fingers as many times as you will have to remove and install them. Also I suggest you get a JR ball link sizing tool. This will help you get just the right fit on the links, so they operate smoothly. This will make your heli fly better and increase battery flight times. For instruction on how to use this tool, you definitely need to watch Finless's ball links 101 video.He suggests you get a few spare links to practice on, but I was able to get mine right by just going slow and not opening them up too much at a time.

The soldering iron was used to attach the XT60 connectors to the speed controller wires. This 40 watt model from Radio Shack works fine for me. You can also use Deans connectors. For a solderless connection, you could go to Anderson Power Poles. This type connector is crimped on but the crimping tools is quite expensive. You could also do away with any soldering by getting your local hobby shop to do the soldering for you. I suggest you learn to solder though.


A pitch gauge is a must for setting the angle of attack for your blades. I purchased the Align model,it's fairly simple and it works well. I also purchased a flybar lock to use when setting pitch from Rick Lohr at Clearly Superior Products. He machines these items out of lexan and they work great. While you can get by by sighting the flybar and pitch gauge, it sure is nice to just slide the lock on and get it perfect.

The Dremel tool and cut off wheel were used to grind a flat spot on the motor shaft where the pinion grub screw lands. This is not absolutely necessary but I highly recommend it so that your pinion does not slip on the shaft. While the Dremel makes quick and easy work of this, you could use a hand file to create the flat spot.

A swash leveling tool is a optional. You can see how the head is setup without it as Bob does in his CCPM setup videos, but I found using Mike Trueblood's tool and his instructions much easier in getting the swash level. It also is used to eliminate any CCPM interaction. There is still a ton of important info in Bob's set-up videos, so be sure to watch them for a complete understanding of the setup process.

You will need a way to make measurements. A simple metric ruler will work, but if your like me and your eyesight is not that great, you will want to invest in a digital caliper. It not only gives you a more accurate measurement, but outputs the results onto a digital display that you can actually see. I found this set on Amazon for $12.95

Any pair of needle nose pliers will do and their was a small Phillips head screwdriver included in the kit that worked fine for the few screws of this type in the kit.

Now for a battery charger. There seems to be a lot of debate on which one to buy, as many suggest you get more than you need at this point in anticipation of moving to a larger heli with greater power demands in the future. I decided on Bantam's e-Station BC-6DX which is Bantam's newest release of the BC model ($139.00). The older version is still available and if your looking to save a little money you can get it for $119 at RC Acessory. Both have a built in balancer and AC power supply. The deluxe version has just been released and I plan on posting my impression of this charger once I've put it through it's paces. As far as the original BC-6, I found nothing but good reviews and I don't think you can go wrong with this charger. You can find cheaper chargers that will suite your needs such as this Turnigy brand from Hobby King but with the hazards imposed while charging lipo batteries and the risk of fire, I felt more comfortable not scrimping on the cost of this item. I suggest you visit this page for charger comparisons and information that will help you in choosing a charger. Last but not least, you will need a safe method to store and charge your lipo batteries. I personally will be charging mine outside in a steel barbecue pit so any possible lipo fire will be contained and away from the house. Fire proof lipo sacks are another option for containing a possible fire, but if used indoors you are still going to have a terrible smoke smell to deal with in the event of a fire. I've also seen it suggested to store your lipos in an old army surplus amunition can that has a one inch hole drilled in the lid to vent. Whatever you do, take precautions as lipo fires do happen.

One of the last tasks of the build was balancing the rotor blades so as to reduce any possible vibration. I tried to come up with a way to use hardware from around the house to make a simple spindle but with the hole diameter of 3mm, I had no long bolts of this size I could use. I figured it was better to just invest 5 bucks and get a tools designed specifically for the job and the Align tool fills the bill.

Consumable Items:

Solder and Flux
Tri Flow Oil
#242 "Blue" Thread Lock
400 Grit Wet/Dry Sandpaper
Denatured Alcohol
CA Glue
Bearing Grease
Blade Balancing Tape

The Tri Flow oil was recommended to me as a good all purpose heli lubricant to use during assemble. I used it to lubricate bearing shafts and as a machining oil while resizing ball links.

Threadlock is used to keep metal machine screws from vibrating loose. The kit supplies you with a small amount, but I bought a extra bottle as I knew I would be using it during any subsequent repairs. For good directions on it's use, check out Finless Bob's video, Thread Lock 101.Bob suggests using purple threadlock in high maintenance areas, but I found that if you apply it as Bob shows, you can use blue and not have a problem removing screws with a hex driver later.

One addditional thing I did during assembly was to clean all the metal screws with denatured alcohol prior to applying thread lock. I just soaked a small amount on a paper towel and then using my hex driver rotated the screw threads into the towel to remove any of the oil that might be left over from the machining process. Then after letting the alcohol dry, I applied the thread lock. I think this was a good idea as some to the screws showed quite a bit of oil residue on them.

I used the sandpaper during frame assembly to sand off all the sharp edges on the carbon fiber frame that could chafe wires that I routed in and around the frame pieces. I didn't want any electrical gear shorting out and quitting on me during flight, A sure road to disaster. It only took a few minutes, so the time investment was well worth the peace of mind it provides.

I used the solder and flux during the attachment of the XT60 connectors to the ESC (electronic speed control). If you've never done any soldering, again Bob has a great video on the process that you can find here.

CA glue (Cyanoacrylate) otherwise known as super glue was used to attach the plastic end caps into the skid rail tubes. Just a small amount does the job and I found no other places where it was needed.

I used silicone bearing grease to pack the thrust bearings when assembling the feathering shaft. This item comes preassembled from the factory, but with all kit parts they should be taken apart and checked for thread lock and in this case grease. Mine was bone dry and there was no thread lock on the feathering shaft screws, so don't neglect to check behind the factory assembler.

That pretty much covers what you will need to get a Trex 450 Sport into the air. The next part will cover assembling all these parts and how to make your bird air worthy.

One last item I want to mention. After considerable reading on the subject of learning to fly a RC helicopter, I decided it would be wise to build and use a set of training gear in an effort to avoid costly crashes right from the get go. To see how I built mine check out this post.

Part Two of this Series