Coast Guard HH52A Helicopter T-Shirt

Here is my latest t-shirt offering. I spent many a day near, in, or under this great flying machine during my tour of duty in the US Coast Guard.

Designed and built by the Sikorsky Aircraft Corporation, the HH52A SeaGuard was involved in the rescue of more than 15,000 lives! Quite an accomplishment when you consider only 151 of this type aircraft were ever built. If you're as big a fan of this aircraft as I am, you can purchase your HH52A t-shirt in the aviation section of the Poker and Chaos Store.

Building a Trex 450 Sport (Part Two)

In part one of this series, I covered what you will need to get started building the Trex 450 Sport RC helicopter. Now that we have all the items necessary, it's time to discuss the actual build process.

The first thing I did was to get a copy of the instruction manual for review. It's available online here. The manual is not a step by step set of instructions like you might expect. It does however provide exploded diagrams of the helicopters sub assemblies as well as important notes. There are also explanations of electrical component programing along with basic set up and safety information. You will want to review all this info prior to starting your build.

The next thing I suggest you do prior to starting any part of the build, would be to watch Finless Bob's instructional videos at HeliFreak. Start with Bob's Heli Skills and Set-Up Basics. Watch the following video titles as there will be information that you need to know in order to build and set up your model.


Ball Links 101 (20 MB)
BEC 101
Blade Balancing 101 (30 MB)
Blade Tracking 101 (35 MB)
Brushless motor and ESC 101
CCPM Setup Part 1 (58 MB)
CCPM Setup Part 2 (58 MB)
Dual Rates 101 (71 MB)
Exponential 101 (45 MB)
Gyro 101
Gyro Gain 101
Pitch and Throttle Curves 101 (58 MB)
Servo Wires 101 (41MB)
Soldering Deans Connectors 101 (30 MB)
Thread Lock 101 (15 MB)

The next set of videos that you should watch are from Ashley Davis at helituning.com. These videos cover the actual build of the Trex 450 Sport. I would watch them each all the way through then refer back to each as you are building your model.

T-Rex 450 Sport Build Videos
Rotorhead Build
Frames Build
Tail Boom Install
Main Gear, Head and Tail Install
Electronics Install & Finishing Off

The build will basically be done in sub assemblies. The head, frame, tail and electronics. Then you will need to set-up the head, program the speed control and gyro. I began by dry fitting the entire helicopter short of installing the electronics. This gave me a feel for the order in which I needed to install components before I did final assembly. Only then did I apply thread lock to all components. As far as using thread lock, watch Bob's thread lock 101 to see how it should be applied. Bob covers the different types of thread lock but I've found that the Sport only requires that you use blue threadlock on all metal to metal screws. (also checkout my threadlock post) The kit comes with a small bottle of thread lock, but I've heard many Sport builders say that it's not the best quality, so I suggest you do as I did and buy a tube of Blue Locktite #242. This worked very well for me and you can still remove a screw if you need to. If you run across a stubborn one that doesn't want to come undone, just apply heat to it for about 60 seconds with a hot soldering iron and it will come right out. When using the self tapping screw that go into plastic you will not want to use locktite. These should hold ok as long as you don't over torque them and strip the plastic. If you make a mistake and strip one, you can apply a very small amount of CA or super glue to the threads to secure them.

Once I was familiar with all of the components. I went back to the head assembly and checked each screw for thread lock. This is very important as I found several screws that had absolutely no thread lock which would surely have lead to a crash. Another thing I did with each screw was to clean it with denatured alcohol to remove any residual oil that might have been left over from the machining process. The oil can have an adverse effect on the thread lock. I would take a paper towel saturated with alcohol and grab the threads of the screw, then using my hex driver, I would spin the screw in the paper towel while pinching the threads with the soaked paper towel. I repeated this process until no more residue showed up on the towel. Then I made sure the alcohol had dried before I applied Locktite and torqued the screw down. Be careful not to over tighten the screws as you can break them. You want to apply just enough pressure to secure them and leave the locktite to do it's job keeping it from vibrating loose.

Also at this point you will want to watch Finless Bob's video on the Trex 450 Pro head build.

Pro Head Build Part One
Pro Head Build Part Two

While these videos show the head build for a Trex Pro, the head is very similar to the one on the Sport and Bob gives some great info in these videos. Pay particular attention to the part where he shows you how to grease the thrust bearings as mine were totally dry and required I repack them. Another note of caution, when you assemble your control arms for the head, notice that there is a small letter "A" die cast into the ball link. Be sure this "A" is facing out when you attach the link to the ball. The reason being that the side opposite of the "A" has a slightly larger diameter. If you accidently get the "A" facing in, the link can break or pop off during flight. This would cause a crash.

Building the frame would be next. Again, watch the helituning video for this as he does a good job on building the frame. Ashely mentions it, but I want to stress the importance of sanding smooth all the edges of the carbon fiber frame. The stamped edges are very sharp and can easily cut wires if not smoothed over. Use caution when sanding the CF as the fibers can irritate the skin and respiratory system. I suggest you use a dust mask during the sanding process and be sure to clean the frame parts after you are done. I would also do any sanding and clean up prior to installing the motor as you don't want fiber to get inside it.

One thing I want to point out is that the 450M motor that comes with the Sport is called an "outrunner". This was not the typical small electric motor I was used to seeing. The outside of the housing spins around the armature on the inside. Strange I know, but it works great. You just have to be careful and keep all wires and your hands away from it. You also want to take a dremel tool and grind a flat spot onto the motor shaft where the pinion grub screw will land. This is not shown on the plans, but greatly increases the holding potential of the screw. To keep metal particles out of your motor, poke the shaft through a plastic bag so that the bag covers the motor during the grinding process.

Take note of any screws that the manual refers to as "self tapping", these will be screwing into plastic and you don't want to apply thread lock on them. You will also need to take care to not strip the plastic by over tightening them. If you do happen to strip the internal threads, yo can apply a small amount of CA glue to the screw threads to secure it.

One modification I made to the frame was to replace the stock gyro tray with a lexan tray made by Rick Lohr at Clearly Superior Products. This provided me with a flat surface that I could use to mount my receiver under the gyro which was farther away from the motor wires and ESC. I found out the hard way that about radio interference when I crashed because of a glitch caused by the motor wires being to close to the receiver. Since using Rick's tray, I've had no more interference problems.

After the frame has been assembled you will want to attach the landing gear. Be sure to apply a small amount of CA glue to the skid pipe end caps before you pop them on. Another tip is to soak the rubber landing skid nuts in soapy water so that they slide on nice and easy. As they dry they will secure themselves in place.
Unlike the plans, I put the nuts on the inside of the skids so they would not over time work their way off the ends of the skid pipes. You can see this in Ashely's video.

Assembly of the tail and boom is pretty straight forward and is well covered in the helituning videos. One item that is easy to over look on the tail is the slide shaft bushing. This must be cleaned and thread locked or your going to learn how to do rapid piros way before you are ready to handle them. Not a good thing! Check out this post for a full discussion on this subject.

Here are a couple more items you need to look at on the tail. I've found the boom has a tendency to slip back into the blocks causing the belt to loosen. Some have taken the boom blocks and sanded the inside flats so that they grip the boom better, but I just wrapped a single layer of 2" wide clear tape to the end of the boom where it enters the block. This easy fix seems to have corrected the problem. Another note of caution, the tail belt can be installed backwards. The tail rotors should turn with the leading edge (fat edge) going up into the main rotor wash. If you notice this is backwards when you spin the main rotor clockwise, you have the belt turned in the wrong direction. The belt and rotors should spin freely, if not, something is wrong and you need to find out what before you fly. To see just how freely it should spin, check out Finless Bob's maintenance video.

Once you have the tail assembled, It's time to mount your servo's and electronics. I must say this would have been extremely difficult without watching Finless Bob's CCPM set-up videos. Watch them over and over if necessary as you heli will not fly right without getting this part right.

I will cover more on my experience with setting up the head, ESC and Gyro in a future post. Until then I will leave you in Bob's hands.


Part One of this Series

Trex 450 Sport Checklist

All it takes is a failure of just one of the many parts of a RC helicopter to force your smoothly flying machine to become dancing chicken. One loose screw in the air can cost you a hundred bucks or more to fix.

It is for this reason that it is so important to check every critical element of your bird prior to each flight. There are so many parts and mechanical processes that remembering exactly what to check is no easy task. Pilots of full scale aircraft put their lives in the hands of their equipment and have come to rely on written checklists to reduce mechanical problems to a minimum.

Using the same method with your RC helicopter will greatly reduce the number of crashes you experience. Below is a maintenance checklist as well as a pre-flight checklist that I use prior to putting my Trex 450 Sport into the air. It is based on the Sport and my Spectrum DX6i transmitter but you can use it for a basic checklist for any electric Heli.

What Type of Thread Lock to use on a Trex 450 Heli

One of the most important tasks in building a RC helicopter is applying thread lock to all metal to metal screws. These machines, with their many moving parts, create ultra sonic vibrations that do their best to loosen screws which will quickly lead to a crash of your new bird.

For this reason, it critical that you inspect each and every screw that has come installed in your kit. Don't rely on the factory installer. Every builder that has put together an Align helicopter kit will tell you that they have found screws that did not have thread lock applied.

I use the Locktite brand of thread locker which comes in several different types. Each has it's own characteristics as far as color, holding strength and applications. The primary types of Loctite are as below:

Locktite Purple #222: This is a low strength thread locker that is used on screws that require easy disassembly.
(See Technical Data Sheet)

Locktite Green #648: Is a wicking type designed for bonding cylindrical fitting parts like bearings and motor shafts.
(See Technical Data Sheet)

Locktite Blue #242: Designed for medium strength thread locking where disassemble might be required.
(See Technical Data Sheet)

Locktite Red #271: Designed for high strength permanent locking of threads.
(See Technical Data Sheet)

From my experience, you'll want to use Blue Locktite#242 for all metal to metal screws on your Trex 450. Watch Finless Bob's thread lock 101 video and see how he applies a small amount to the end of the screw then wipes the excess off with his finger. A little goes a long way. Apply it in this manner and you will have no problems getting a screw out for maintenance. If you do find a stubborn screw, don't try to force it out, you will scrip the head. Instead, take your soldering iron and put heat to the head for about a minute and it will break the locktite down so that the screw will come loose.

A word of caution, there is no need to use red locktite anywhere on a Trex 450. The red creates a permament bond that will create havoc as you need to remove parts during future repairs. Bob mentions that you might want to use purple thread lock in high service areas as it is easier to remove, but I've never had any problems getting blue lockite to release after a little heat.

The green can be used to secure bearings so that the outer race doesn't spin in it's housing. Be careful as you don't want thread lock inside the bearing. Green can also be used to help lock the pinion gear to the motor shaft. I grind a flat spot on the motor shaft where the pinion's grub screw lands which seems to eliminate the need for thread lock on the shaft.

One last note, you need to clean all screws before you apply thread lock. During the manufacturing process oil is applied to the screw threads as they are being cut. This oil can retard the thread locks holding ability. I use denatured alcohol for this process. Acetone will work also. I soak the screw in a small glass bowl of alcohol and then take the screw, put it on the end of my hex driver and turn the threads into a paper towel removing any oil residue. Once all the oil has been removed, I make sure the alcohol has dried before applying thread lock.

Working on RC helis is a craft that comes with experience. Leaning just how much and how to apply thread lock is part of this craft. I hope this post help you on your way to becoming an expert RC helicopter mechanic.

Trex 450 Sport Training Gear

If you've built a Trex 450 or any 450 class RC helicopter and have never flown a collective pitch heli before, it will be a wise idea to get build yourself a set of training gear. The set I built consist of a couple of 1/4" wooden dowels about 2" longer than the diameter of the rotors. For the Trex Sport I made mine 30" long. Attached to the ends of these rods are standard size ping pong balls.

To start with, I cut the dowels to a 30" length. Then I marked each dowel at the 15" center line. This gave me a center on each dowel to align when I attaching them to the heli so that they would balance.

To attach the balls to the dowels I started by heating up my Radio Shack soldering iron which the main tip happens to be 1/4" in diameter. I simply took the point of my hot iron and pressed it into the ball to make a perfect sized hole. I started on the visible seam of the ball so I could keep the opposite hole symmetrical. Once the first hole was burned, I pushed the end of the rod through to the opposite side of the ball again aligning it with the seam. Then viewing from the outside, I marked the spot where the rod had landed with the tip of the soldering iron. I then removed the rod and proceeded to burn a hole at the marked location. Now I was able to slide the dowel all the way through the center of the ball. I repeated this procedure three more times so that I would have a ball on the end of each dowel.

I aligned each ball so that the dowel protruded about 1/16 of a inch out of the side. Then I secured the balls to the dowels by mixing up a batch of 5 minute epoxy and coating the area where the dowels pass through the balls.

To attach the gear to the heli, I pass each dowel through the middle of the landing gear skids and align them in a cris cross fashion with the center marks over each other. I then use nylon tie wraps to secure the middle of the dowels as well as to the skids at the four intersecting locations. To finish up, I cut the excess off the tie wraps and was ready to fly.

The training gear will serve you well during your first few batteries. Get used to taking off and slowly setting your bird back down. Once you have gotten comfortable taking off,landing and using throttle hold you should remove the gear as your bird will be more stable without them.

Good luck!

Trex 450 Sport Build Caution

If the slide shaft on the Sport is not securely fastened to the t-arm, this assembly is sure to separate in flight causing a crash. Most, including myself are not even aware that this part exists until a problem arises. Below you will see the slide shaft labeled part "A". While not indicated in the instructions, the shaft has very fine male threads that screw into the internal threads of the T-arm, part "B". Even if you apply thread lock to the shaft before assembly, you still take the risk of these parts coming apart as the T-arm has an anodized finish that tends to impair the adhesive abilities of the thread lock.

In order to correct this problem, you must first throughly clean the shaft and t-arm with acetone or denatured alcohol prior to applying the thread lock. Also, be sure whatever cleaning agent you use had dried before you apply the thread lock. Once you have applied the thread lock, care must be taken when tightening the two parts. The head of the slide shaft has flats on the end that can be used to hold it from turning as you tighten. It would be best to use a small wrench for this job or if using pliers, be careful not to crimp the shaft as it is fragile.




I hope this information helps you build a more reliable T-rex 450 Sport followed by many successful flights.

Battery Charge Identification Tags

If you own more than one battery for your RC aircraft or vehicle, then you need to keep track of which batteries are charged. These handy little clip on tags are just the right item for the job. Once you have your lipo up to max capacity on the charger, just unplug it and snap on a tag. Then when your at the field and ready to install the battery in your machine, just take the tag off and stick it in your pocket. This way you will always know which batteries are charged and which are not.

Orders yours now. Only $4.99 for a pack of 5 with $1.99 shipping to anywhere in the world.