Thunder Tiger offers up the latest model in the extremely popular Raptor line of R/C helicopters designed by Mr. Shigetada Taya. Mr. Taya also designed the line of Concept helicopters for Kyosho, the model that made R/C helicopters affordable to the masses and you didn't have to be a mechanical engineer to fly them successfully.

This is part one of a two part review and includes the Raptor 50 Titan built and flown as the stock kit arrives on your doorstep. Part two will show the installation and flight testing of several upgrades available to increase the performance and visual appeal of the Raptor.

I've been wanting to build a Titan since they were introduced but the Chief of Domestic Relations where I reside has decided I do not need another helicopter. My quandary was solved when a flying buddy was over seas and mentioned he was ordering one to build when he got back. Being the patriotic friend that I am I advised him to go ahead and order it, have it shipped to my house and I would have it ready for him when he returned. What follows is my experience with building, setting up and flying the Raptor 50 Titan.

Kit Name: Raptor 50 Titan
Price: MSRP $716.99 Street Price $420
Main Rotor Span: 1345mm (52.95") 1391 (54.75") with 620 Blades
Flying Weight as tested: 7lbs 12oz
Blades Used: 620 mm NHP
Engine Used: OS 50SX-H Hyper
Gyro used: Futaba GY 401 w/ 9254 digital tail servo
Governor used: CSM Revlock 10
Radio equipment: JR 10x, JR 649 PCM Receiver, Hitec 5625MG Servos,

Items Required (more on this later)

• Metric Allen Wrenches
• Metal Ruler with MM graduations
• Phillips or JIS screw driver.
• 10 MM Socket Wrench
• Pliers
• 30 Min Epoxy (If flying wood blades)
• Medium CA

The rather large box arrived on my doorstep and appeared larger than the standard 9" x 10.5" x 28.5" box I had been expecting. Upon inspection of the contents it became apparent that my friend had ordered enough parts for an episode of "Pimp my Raptor" including a full metal head, upgraded tail, skids and numerous other aluminum and carbon parts. To be fair to those that plan on purchasing a Raptor and assembling as they come from the factory we agreed that this would be a two part review. This edition will include nothing but the stock Raptor Titan as anyone would purchase it to include the flight testing portion and a separate review will be done detailing the installation of the upgrades and a comparison between the flying characteristics of the stock setup with the upgrades.

The first order of business was to read through the instruction manual which is helpfully available from the Ace website if you wish to browse it before your purchase or read it covertly at work. This is one area where I find lacking in many kits and the Raptor Titan is no exception. If you've built a few helicopters the diagrams and notes in the manual are fine and it will go together painlessly. If its your first kit however there's some things that if done in the wrong order result in some disassembly and reassemble which can be somewhat of a chore. This is where the work of Mike Prewitt comes in handy, Mikes website Raptor Technique bridges the gap between a person entering the hobby with no experience and the Thunder Tiger instruction manual.

After we get through browsing the book its time to assemble the tank. Most of the steps in the instructions are accomplished with a given bag of parts however you have to have an idea what you are looking for. It would be helpful if Thunder Tiger labeled the bags with the step number in the instruction booklet as I have seen some other manufacturers do. Its a small thing but would save some modeler's time sorting through bags of parts to find the correct bag for the step they are working on. I'm not going to try to reprint entire manual or replace the excellent build guide on Raptor Technique, just cover some areas I think need that special attention that make the difference between a smooth flying helicopter and one that has been slapped together.

The fuel tank assembly is step 1 in the instructions and this is where I made the first deviation with two small changes. The clunk line in many kits breaks down quickly so while the stock line is serviceable for a few gallons it will become brittle and collapse on itself and cause the engine to run lean. This is mainly due to muffler pressure from high nitro fuels and the way to combat it is to replace the stock clunk line with a high quality line such as the Hayes line I used in photo two. Also notice I cut 2 short sections of standard fuel line to slip over the connection to use as a keeper, this is a nearly bullet proof tank setup. Step 2 is the pinion and bearing installation. The photo in the manual shows the clutch liner being installed but this comes installed from the factory and the beefed up clutch bell bearing is already pressed in for you. Before putting the bearing onto the pinion I put a thin film of green locktite (photo 3) on the pinion where the bearing will go. Don't over do it, you don't want locktite in the bearing but you want to make sure the inner race of the bearing is secured to the pinion. What can happen is the pinion is made of a softer material and the harder inner bearing race can wear away the pinion causing play, the locktite should ensure it stays put. This is the only instance we will use the green locktite so you can cap it and set it aside, any reference to locktite from now on will be the medium strength blue unless specified. Also the manual shows locktite on the pinion where it screws into the clutch bell but its really not needed as the engine rotation will keep it tight and locktite will make it harder to remove later if you need to replace the clutch bell.

Now its time to lay out the frame and install the spacers. The 4 metal spacers supplied with the kits and hex head screws surround the main shaft bearings. This is a modification that appeared in the later runs of the V2 kits and is a nice addition. This was one of two areas where a decision was made to go with the after market items my friend purchased. I didn't feel the spacers would impact the flight portion of the review and to change them for the Maverikk machined spacer kit would have required complete disassembly of the helicopter and frames so in went the metal spacers (photo 5). If you are using the stock plastic spacers and self tapping screws be sure not to use locktite, if you feel the need you can put a drop of medium CA on the screw but I have never found this to be needed unless you disassemble the frames several times and then its just as easy to replace the spacers. Another area of note during the frame assembly is that most kits assembled overseas do not use standard phillips head screws they use something called JIS or Japanese Industrial Standard. A phillips screw driver will work but JIS screw drivers available from many tool and model helicopter retailers are a much better fit and won't strip the screw heads nearly as easily.

Notice that the main and start shaft bearings appear to have required a blood sacrifice (photo 5). In reality that's bearing grease and brings me to the use of my next neat tool. This is called the bearing greaser or "The Greaser" and is available from Petes Hobbies and is shown in Photo 6. Simply place the bearing in the cup and push down with the plunger and it forces grease into the shield (Photo 7). If you are working on an existing bearing push until the old grease is forced out and the new grease starts to appear around the shield. This simple process during assembly makes bearings last much longer especially if you fly in dusty environments. After this is done to the 4 bearings install the spacers and assemble as per step 3 of the manual.

Step 5 shows the assembly of the washout arms. Notice in photo 11 that there is two holes which you can install the balls that effect the amount of pitch change in the fly bar for a given cyclic input. The inner hole means less throw of the paddles and makes the machine feel more stable and the outer hole is for 3D type flying. Start with the inner holes and once you get used to the machine give them a try on the outer hole, you may find the helicopter is twitchy in cyclic or pitches up or down in forward flight. Any misalignment between the paddles or the effects of the center of gravity not being correct will be amplified by using the outer holes, something you should be aware of but if you follow along the CG and paddle alignment should be correct.

Step 6 is where I ran into the second place I wanted to install an aftermarket part to avoid problems later on. He had purchased an upgraded elevator A arm and rocker set so I thought I would go ahead and install it at this time. The problem is the after market part is quite a bit wider than the stock one because of its design and needs to be installed when the frames are split, since I didn't want to bother with that again, and the stock parts work fine on my Raptors I set it aside and went to work on the rest of the frame assembly. During the installation of the A arms another potential problem can be avoided. Thunder Tiger links are unidirectional and are designed to snap on the ball one way, on the push rod linkages this is a simple matter of snapping them on so the logo goes to the outside.

On the flybar control rods and the A arms however there's no marking so you need to take a moment to orient them correctly and mark the outside, I use a silver sharpie. Set the A arm link over a ball on the swash plate without snapping it on and take note of how much of the ball is covered by the link, now flip it over and do it again. One way will cover more of the ball, that is the correct way to snap on the linkage, mark the outside and take note to build and install the control rocker so that they snap on correctly. The pins (item 3 step 6-1) are a friction fit in the rocker (item 1) this would have been a nice area for Thunder Tiger to supply C clips so do yourself a favor and take a look at the pins prior to the first flight of the day.

During this step (or earlier if you follow Raptor Technique) you will need to build and install the intermediate elevator pushrod so I'm going to take this opportunity to introduce you to more time saving tools. Out came my Quick UK ball link tools (photo 12 and 13) which save a LOT of wear and tear on the finger tips and make short work of assembling the many push rods in an R/C helicopter. I picked up some inexpensive calipers from Harbor Freight they have both dial and digital, I use dial and I don't have to worry about the battery. Photo 14 and 15 show how to measure pushrods according to the manual. You can get more expensive caliper sets but they don't really have to be super accurate just consistent. I also purchased the Vario pushrod tool, a set of nubs that attach to calipers and are used to make identical pushrods, photo 16. Finish the frame assembly in steps 6 and 7 in the manual and at this point we are ready to put the engine together.

The engine to power the Raptor Titan was an easy choice, the OS 50SX-H Hyper. Sporting an enlarged heat sink for improved cooling and a larger throat carb than its older brother, the venerable OS 50SX-H, the Hyper produces more power and the new carb solves the midrange leaning issue that some people had with the original 50. I have found that OS engines are highly reliable, produce excellent power and are very consistent. If you are starting out on a budget and don't need the extra power the Thunder Tiger 50 is a good motor and is more economical to run in terms of initial purchase price and fuel economy. Take some time to inspect the motor as I found the carb misalligned so check the head bolts, make sure the carb is pressed down, the index marks align (photo 18) and when you remove the backplate to install the fan look for machining debris.

It came time to make another decision in regards to after market parts installation. My friend had ordered a CNC cooling fan and again I decided to go ahead and install it now so a major over haul wasn't required later, this is an amenity and the stock fan will work fine. Careful inspection on the aftermarket fan on the left of photo 19 will show two relieved areas for the clutch shoes, if you install a fan with these areas there is no need to install the shim on the clutch (photo 20), if you install the shim be sure to orient it as shown in photo 20. Here is another area which you could probably skip and get away with but I like to mount the clutch and fan along with the governor magnet if you are going to use one and balance it as a unit, mine was right on (photo 21). You are going to have to remove the clutch to install the fan so mark it and the fan so you put them back together the same way.

When installing the engine loosely mount the motor to the motor mount and install the entire assembly into the main frames. Mount the motor mount to the frame and tighten the 4 frame to mount bolts (if you are using a remote glow wire, a good idea unless you want to remove the canopy each start, install it now to the lower motor mount bolt on the right side). While spinning the start shaft backwards with your finger tighten each motor mount bolt until you feel resistance and back off a 1/4 turn. Continue this process until all 4 motor mount bolts are tight and there is very little resistance in the start shaft, this will ensure nearly perfect clutch to start shaft alignment. While you are working the motor mount bolts be sure to align and set the gap for the governor sensor, there should be about 1 to 2 mm clearance between the magnet and the sensor.

Its time to assemble the rotor head. This isn't overly complicated but there's a few things to be aware of. The first is that there is a correct and wrong way to assemble the thrust bearings, do one at a time so as not to mix up the bearing races. Doing this correctly will go a long way in preventing blade woof or the blades going out of track in a hover or maneuver. Slip both washers over the spindle, one will rock side to side more than the other, the one that rocks more goes towards the main rotor hub. Something else to watch for is to orient the flybar control rods (hoops) correctly, follow the diagram on page 12 and notice the short link goes towards the top of the rotor head. Also remember the elevator A arms? The hoops are the same way, sit one over a ball to determine the correct direction to snap it on as these are also brittle and can crack if pushed over the ball the wrong way. You also want to put some silicon dielectric grease on the spindle (item 7 step 11) where it goes through the rubber flap dampeners (item 9) or the rubber will grab the spindle as it pivots and will result in nodding during a hover and forward flight. Also put some grease on the balls and races from the thrust bearings when you install them. I like to run a spindle bolt in and out to make sure none of the dampener grease is in the threads then locktite these bolts, you will need an extra allen wrench for this step.

Step 12 involves they flybar assembly. Care should be taken to align and center the flybar carefully. There should be 158mm of flybar sticking out of either side of the head assembly before the paddles are installed. The short double links that go from the washout arms to the main blade grip are installed during this step and you should take care to install them the correct direction, use your silver sharpie to mark them. Its time to introduce another helpful tool, the ball link reamer. Most of the ball links from the factory are fairly tight, most of them in the head will loosen up after a few flights but the links in the control system and A arms wont. I test fit all the links before I install them and if needed give them a few twists of the reamer. (Photos 25 and 26) Don't do too much at a time, you can always take more material off, you can't put any back on. If your links are too tight your servos will have trouble returning to center and you will be constantly chasing the helicopter and keeping it in trim.

When installing the upper mast bolt make sure its snug but don't over torque it, this bolt can break if over tightened and when that happens the head comes off in flight, the resulting landing is usually less than visually appealing. Screw the paddles on until the fly bar just starts to show in the small cut out in the paddle, install the set screws in the paddle but don't tighten them down just yet. You can align the flybar paddles by eye and most of the time get pretty close but a set of paddle alignment gauges allow you to get perfect alignment every time. As you progress in your flying and start using lighter paddles like we will in the upgrade segment alignment becomes critical. Photo 27 shows the use of the gauges and the paddles out of alignment, tweak the paddles and get them perfect as photo 28 shows. The paddles should be aligned to the head and each other. Photo 28 shows the paddles in alignment (top of each gauge parallel to each other) so you can tighten the set screw, just snug it you don't want to strip the plastic and leave the gauges on so you can verify alignment when everything is tight.

At this point the helicopter should really be taking shape but its time to give it that final piece, the tail and tail rotor assembly. I built the Titan for its initial flight testing stock but I highly recommend replacing the tail rotor hub and grub screw arrangement with Thunder Tiger part number PV0499, its a one piece machined assembly that is much more robust, the tail case and tail rotor will be replaced in the upgrade phase of our Titan so I felt the stock assembly would be adequate. Take care not to over torque the grub screws (step 14 item3) as this will contribute to early tail rotor failure. When installing the tail pitch change fork (item 13) tighten it while spinning the slider assembly (item 14 step 14) until you feel the bearings start to bind then back it off 1/4 turn so the bearings run smooth, if you over tighten this and bind the bearings they will get VERY hot in flight. Photos 29 and 30 show the red tail pulley, the edges are beveled and it should be assembled as in photo 29, if you get this backwards you will have 2 or 3 mm of side to side play in the tail rotor output shaft and your gyro will always feel mushy and the tail won't give you that "locked in" feeling.

Two things of note while assembling the tail case, make sure the washer for the bell crank goes between the bell crank and the tail case I have found some binding where the builder used the washer next to the bolt head. Be sure to keep an eye on the ball on the pitch change slider and the bell crank, this area can pick up a lot of grit and it acts like a lapping compound and wears the ball down and makes for a loose fit on the bell crank, the result will be tail kicking. Another area of note is the belt installation. Poor tail performance can often be tracked to the belt being twisted more than 1/4 turn. When you install the tail boom and loop the belt over the spur gear when the main rotor head is turned clockwise the tail rotor should turn counter clockwise when viewing the right side of the helicopter, another easy way to remember is if the tail rotor hits the dirt it should always throw dirt towards the front of the helicopter. This ensures the advancing blade is moving up and into the main rotor wash and makes the tail rotor more efficient.

We are on the home stretch now and its time to install and setup the servos. I wont go into individual radio setup because everyone has their favorite radio brand and Raptor Technique covers many popular radios but I will give you some tips to get your mechanical setup right. We start by choosing servos and my personal philosophy is get good servos from the start. Some people think this is a good place to save money but you are just cheating yourself as you will either want to upgrade later and you end up buying twice. Also the cost of a crash due to failed or stripped servo will generally meet or exceed the cost of buying decent servos to begin with. All of my Raptors use the popular Futaba 9252 servos and these are on the high end of what required on a 50 but they hold up very well and are fast and powerful, I have never had a 9252 fail in flight on me.

My friend chose to go with the Hitec 5625MG metal geared servos rated at a whopping 110oz of torque at 4.8 volts and a respectable speed of .17 for a reasonable $55 dollars each. When servo plates are used as supplied in the Raptor kits I leave out the brass collets especially on the collective servo so you don't get any movement of the servos during hard maneuvers. Also since we are using metal geared servos don't forget to locktite the servo arm screws, ensure you do not locktite nylon or karbonite geared servo screws because as before, locktite will attack the plastic and make it brittle. Photo 33 shows the how to achieve perfect pushrod length as the numbers in the guide are close but different servos can vary those settings. For a simple linkage like the throttle just measure from the center of the throttle arm screw to the center of the servo arm screw and build your pushrod to match that measurement, the Vario pushrod nubs and a caliper make tweaking later a thing of the past. Don't forget to size the links so everything operates smoothly.

A handy tool I mentioned earlier is the Hanger 9 inline amp meter. If you plug a servo into one side and plug the other side into the receiver its almost painfully simple to ensure that your control system is free of binding. This is especially important with digital servos as they can sap battery power at an alarming rate if the servo is stalled. Photos 34, 35 and 36 show me adjusting the limit pot on the 401 gyro to ensure no binding. As you can see we started out with .1 amps, not bad but a little tweaking and we are right in there. A stalled digital servo can pull upwards of half and amp or more, this is especially important when setting up the throttle linkage and the push pull linkages.

Speaking of push pull linkages the Titan sports push pull on all 3 major controls now including the elevator and collective. If you prefer to use a canopy mounted rudder servo the push pull collective assembly can be left out, this is personal preference item. The chief advantage of the push pull setup is the side loads on the servo are lessened but top pilots have been flying Raptors for a long time with a single collective rod. The chief advantage of a canopy mounted rudder servo is less oil on the servo, less vibration transmitted directly to the servo gear train (this is worse with the upgraded carbon rods) and better protection in a crash. If you choose to stick with push pull then when building the collective push pull rods make sure you use the short shouldered ball link ends and get the pushrod measurements as close to perfect as you can.

According to Futaba the 401 should be set by adjusting the linkage so that there is no drift in rate mode, on the Raptor this is quickly accomplished by setting the tail pitch slider so that there is 4.5 mm between the brass slider and the tail case, in each case this has worked out perfectly so we set the Titan there this time as well.

Our test Titan was setup for -10 and +12 degrees pitch mechanically. Normal flight mode was set for -5 to +10 with 0 at mid stick and 1650 head speed. Idle up 1 was enabled and set for a linear pitch curve of -10 to +10 and a governed head speed of 2000 rpm which puts the hyper in its happy spot of 17,000 rpm. Throttle hold was set for -6 to +12 and we decided to revisit that later. Most helicopters have a happy spot for doing auto rotations that depend on blade weight, design and overall weight of the helicopter and I have found that somewhere between -4 and -6 gets the most bang for the buck as far as maintaining blade speed. Not enough negative pitch and you loose blade speed, too much and it merely falls faster without increasing the head speed. As you will see in the flight testing the Titan autoed more like my 90 size Avant than my Raptor 50 V2.

It was hard to enter the flight testing phase without any preconceived notions as myself and Randy the owner have 10 Raptors between us. When the weather and our work schedules finally cooperated there were no more excuses and it was time to put her in the air. The hyper was set to 2 1/2 turns with Cool Power 15 percent fuel and fired up and allowed to sit at a high idle for a few minutes. Modern engines to not need extended break ins but I knew from prior experience with these engines they benefited from gentle treatment for a few tanks. After the engine warmed up a bit we did some basic hovering and the Raptor hovered just a slight amount of right trim. This is to be expected from a clockwise rotation main rotor and is called translating tendency and is caused by the tail rotor blowing the helicopter to the side.

The Raptor settled into a smooth hover but the tail was kicking and the engine sounded very rich so we turned the needle in 4 clicks and the hyper started to smooth out. A few tanks of hovering and flying circuits and the backplate was getting cooler to the touch indicating the ring was seating and the engine was breaking in nicely. After we had the top end setting close we performed the pinch test and had to lean the low end slightly to get 4 seconds of smooth idle before the motor started to speed up.

With engine break in and trimming completed we put the Raptor through its paces. We found the Titan to be very stable but a bit slow in cyclic response. This was to be expected with the heavier black paddles, soft blue dampeners and longer blades. Tail performance even with the stock tail blades was fast and crisp. Auto rotations were smooth and predictable with plenty of energy at the bottom to enter a hover and land. When the local expert Wayne Clarke flew the Titan he landed, took off, did a piro and landed all in throttle hold, very nice! While the longer blades and heavy paddles detract from the 3D performance they make a very stable training platform and should serve anyone from a beginner to intermediate flyer very well. Hirobo paddles are weighted and as you progress you simply remove the weights and adjust the linkages and that is why in misses I've listed that you need to upgrade some components for serious stick banging such as paddles, dampeners and a metal head block (optional but the plastic head block can wear quickly at higher head speeds).

See the Raptor 50 Titan in action!

Thunder Tiger has another winner on their hands. The Titan continues the successful pedigree of the Raptor line and its enhancements though subtle are worthwhile especially the ability to swing 620 mm blades as it lets the pilot put more of the torque of the 50 Hyper engine to the blades. Even in the stock form the Titan easily performed loops, rolls, upright and inverted funnels, elevator and aileron tic-tocs with ease and grace. It was very stable in the hover and will take a beginner pilot from basic training through intermediate 3D in a moderately priced package that is easy to assemble and maintain.

Thunder Tiger Titan
Retail and Sold in the US by:

HeliProz.com

Thunder Tiger
Distributed in the US by:

Futaba & OS

Distributed in North America by
Great Planes Model Distributors
P.O. Box 9021 Champaign, IL 61826-9021 Website: http://www.futabarc.com http://www.osengines.com Products used: OS 50SX-H Hyper Futaba GY-401, Futaba 9254 Servo

CSM
Distributed in the US by

Advantage Hobby
PO Box 6988
Champaign, IL 61826 USA
Phone: (217 867-2300
Web Site: http://www.advantagehobby.com
E-mail: ihelp@advantagehobby.com
product used: CSM Revlock 10

Hitec

Hitec RCD USA, Inc.
12115 Paine St.
Poway CA, 92064
Phone: 858.748.6948 Website http://www.hitecrcd.com
Product used: 5625MG Servos