T-Rex 450S Review

The following is a full build & review of the T-Rex 450S.

 

The items used in this build are as follows:

Align T-Rex 450S
Align 430L motor - included in kit
Align 35X 6V ESC - included in kit
Spektrum 6200 rx
LogicTec 2100T gyro
Hitec HS-56 Servos
Futaba 9650 tail servo

I will go through the build a step at a time. I have not followed the manual as the 450S comes mostly assembled. I built the model in the most logical manner given what is already assembled.

 

Build

 

When you open the box there does appear to be quite a lot of different bags of bits and pieces and the initial impression is that there is quite a lot to do. In reality most of the complex building has been done for you. The rotor head comes preassembled, the upper and lower frames come preassembled. Essentially building the T-Rex is a matter of connecting the upper frames to the lower frames, installing the tail gearbox onto the boom, installing the boom onto the main frames and then inserting the rotor head through the main shaft bearings, through the main gear and securing in place.

However, I would thoroughly recommend that any screws that are going into metal should be removed and some loctite applied and then replaced. Specifically the blade grip screws that go into the feathering spindle had no loctite on them at all, neither did the tail blade grip bolts.

My approach to the build was to assemble the main frames first and then bolt everything else onto them.

As previously mentioned the upper and lower main frames have already been assembled. The kit contains a bag with all of the screws and the motor mount in it, this is the one you need to bolt the main frames together. Remember to use loctite on all of the screws going into metal and do not use loctite on screws going into plastic as the loctite will soften the plastic.

The build of the main frames also includes installation of the anti rotation bracket as well as installing the extended battery tray. The pictures below show the build up of the main frames and the associated parts.

 

The next two tasks are very quick and easy to accomplish. Firstly the main gear should be inserted into the frames and lined up ready for the main shaft. Secondly the preassembled rotor head and main shaft should be inserted down through the main shaft bearings, through the main gear and then secured in place using the provided bolt and nyloc nut.

 

The next task is to install the undercarriage. This just consists of inserting the undercarriage rods into the struts and then bolting the whole assembly to the underside of the main frames.

 

The next section is about finishing the rotor head. The flybar carrier, flybar and paddles need to be installed on to the preassembled rotor head. Also the main shaft locking ring needs to be tightened into place ensuring that there is no vertical play in the main shaft. The flybar can optionally be fitted with the supplied flybar weights for beginners. Advanced pilots will want to leave these in their packet. The flybar should be centered and locked into place, the paddles can then be installed such that they are equidistant from the flybar cradle. The paddles also need to be lined up so that they are in line with the flybar cradle. In other words if the flybar cradle is horizontal then the paddles should be horizontal as well.

 

The next task was to install all of the tail boom accessories onto the tail boom. This includes the servo mounts as well as the plastic guides for the tail pushrod. The pictures below show these installed and the boom installed into the main frames. However, at this point the boom should not be installed into the main frames as the tail gearbox needs to be fitted first.

Strangely enough the next item is the installation of the tail gearbox onto the tail boom. The tail gearbox has a single screw which clamps it onto the boom. This should be slackened and the belt unwound and threaded through the boom. I use a piece of string tied to the belt to pull it through the boom. It's virtually impossible to either dangle or push the belt through the boom on it's own. Another method for getting the belt through the boom is to use a coathanger that has been bent and unwound and made into a little hook. This is then pushed through the boom, hooked onto the belt and then the belt pulled back through the boom.

Once the belt is through the boom the tail gearbox clamp screw can be tightened. This is just to hold it in place for now. It is important at this stage to look down the boom and get the belt untangled and without any twists. Once this is accomplished the boom can be inserted into the main frames. The belt is then given a quarter counter clockwise twist onto the tail drive pulley. Pull the tail boom back to tighten the belt slightly and then do up the tail boom clamp screws temporarily to just hold it in place.

 

At this point the main elements of the build and have been completed and now it's a case of installing various bits and pieces to complete the machine. The first of these are the horizontal and vertical fins, tail boom struts and the tail blades. Having fitted these without doing up any of the screws too tightly it is time to line up all of the components of the tail boom. What I mean by this is getting the tail gearbox aligned so that the tail shaft is horizontal, making sure the vertical fin is indeed vertical and that the horizontal stabiliser is nicely lined up and at 90° to the vertical fin. Once all this is done all the various screws can be tightened up and, where appropriate, loctite applied.

Alsot check that the tail belt is installed correctly by rotating the rotor head clockwise when viewed from above. The tail rotor should rotate anticlockwise when viewed from the right-hand side of the machine. If the tail rotor is rotating the wrong direction then you need to remove the existing 90° twist and add a 90° twist the opposite way.

 

The kit comes supplied with the Align 430L brushless motor. This should be fitted with the 13 tooth pinion for 3-D fliers or the 12 tooth pinion for beginners. I filed a flat on my motor shaft using a Dremel so that the grub screw would stop the pinion from rotating on the shaft. Once the pinion is installed the motor can be bolted into the motor mount using the screws and washers supplied. Don't forget to fit the motor with the supplied bullet connectors before installing it into your main frames.

All of the head linkages can be built at this point and installed onto the preassembled rotor head. I found the measurements for the control linkages to be absolutely correct in order to get + / -10° pitch. In order to set the linkages at the correct length I used a digital vernier. Once you have installed all of the linkages onto the preassembled head you should be left with three linkages of different lengths. These are the linkages that fit onto your servos and connect to the swashplate. Put them somewhere safe for now.

The kit also comes with the Align 6 V electronic speed controller. This should be fitted with the appropriate bullet connectors before being secured with double sided foam tape onto the main frames. The instructions explicitly state that you should not secure the speed controller to the main frames using cable ties and that this will invalidate your warranty. Also it is worth noting that this particular speed controller in the past has had the heat sink glued to the plastic shrink wrap rather than the circuit board itself. This is not the case with this new offering and the heat sink has been installed correctly onto the circuit board.

 

 

The last task is to install your chosen servos, receiver and gyro. Some things to note are that the main frames are not drilled to accept a servo with four mounting screws (like the HS 56 and HS 65). I therefore modified my servos so that they could be fitted using a single centre screw. This just involved drilling a small hole between the two holes already drilled into the servo for mounting screws.

I chose to fit a Spektrum AR6200 receiver on the front battery tray as I will be using my 2.4 GHz DX7 transmitter with this model.

Below are some pictures of the completed model with the canopy removed.

That completes the build information. I have deliberately kept it fairly short as the majority of the kit is already built and it is just a case of bolting together the fairly large and preassembled components.

Flight Testing

I installed the 13 tooth pinion initially for flight testing but subsequently this was changed to a 12 tooth pinion as the motor seemed to be happier running on a slightly smaller pinion. The initial lift off into the hover showed that I had a tracking problem and after various adjustments I was unable to get rid of this problem. Usually this is down to worn dampers or a problem with the blades. As the dampers were brand new I opted for changing the blades. Having swapped the blades the tracking was now spot on. I am not a big fan of the Align black and yellow blades as they are too heavy, too flexible and often not well balanced, in this instance they were unsuitable for use all together.

Having sorted out the tracking I set the head speed using the governor at 90% throttle in idleup one. Now I could give the model a proper test and see how it performed.

Initial flight tests were just hovering to get a feel for how stable the machine could be. The 450S is very stable for a small helicopter and a novice should be able to hover it without problems having spent sometime on a simulator. Moving into forward flight cyclic control was progressive and positive. Align have finally resolved all of the problems they had with early kits in terms of the links being stiff and this definitely helps in producing a much smoother flying machine out of the box. Again, a novice would not struggle flying the T-Rex in lazy eights or gentle circuits it really is a nice smooth flying machine.

Now it was time to push a little harder and see what she could do when pushed into some 3-D. My first maneuver was a straightforward tic toc and I immediately felt the presence of the 430L motor which although perfectly capable of providing power for 3-D it is not as powerful as the more recent 430XL. Therefore, the tic tocs were slightly more rainbow like than a tight tic toc. Moving on I went into forward flight and pulled up into a large loop. Again I felt the presence of the 430L motor and again wished for a little more power. Nevertheless, the T-Rex pulled through a very nice large loop. I just had to work a little harder to coax it through on the collective pitch.
Following this I did some pie dishes and funnels. Here I experienced some tendency for the tail to blow out a little more early than I was expecting, I can't explain why this was the case as the tail assembly is almost identical to the T-Rex SE V2 except that the blade grips and tail gearbox are made from CNC materials in the latter. I put the T-Rex through some backwards inverted hurricanes and again the tail had a tendency to want to wander but it was controllable throughout. I changed to a GY401 gyro just to check it wasn't gyro related but this did not resolve the tendency to blow out a little early.
Lastly I did some pirouetting flips and some chaos and although I felt myself wanting a little more power the model was willing to perform the maneuver without too much trouble.

One thing I did notice throughout the flight manoeuvres was that the collective pitch although willing to provide the required pitch changes was not as progressive as that of the T-Rex SE V2. Neither would I expect it to be as good as this as the 450S does not have the thrust raced blade grips of it's more expensive brother.

All in all the 450S flies very similarly to the previous T-Rex SE V1. Which is high praise indeed for a helicopter that only costs £150.

 

 

 

 

Conclusion

Once again Align have proved that they can improve their product line systematically with each new release. I was not expecting the 450S to fly as well as the T-Rex SE V1 but it is a very competent performer no doubt helped by the new aluminium stacked frames.
This model would suit a beginner as much as it would suit somebody looking for a cheaper model to practise 3-D manoeuvres. It is stable enough that a beginner could learn to hover on it (with previous simulator practice) and competent enough to move the beginner onto aerobatics and eventually full 3-D flight. Additionally as with all T-Rex the model can be upgraded with parts from the T-Rex SE V2 allowing the owner to upgrade over time as their skills progress. My only disappointment was the awful blades supplied with the kit, they were not balanced well and would not track which for a beginner would be very frustrating. Align really should consider using their 325 pro wood blades which are all together better than the plastic fantastic black and yellow blades supplied in the kit.

Overall, excellent value for money, more than adequate quality and a competent performer.

 

Distributors comments on the review

Align UK asked for the option to provide their own comments on the above review. I've not been asked to do this before but see no reason not to provide the facility:

Firstly thanks to Ash for a first class honest review, something you don’t always see in a magazine.

The T Rex 450S represents amazing value for money and builds on the developments over the past few years on previous versions of the T Rex 450.
The supplied speed controller is the same one as supplied in the class leading 450 SE V2 and the built in BEC supplies enough current that a separate BEC is not required, the 6V BEC out put means also ensures the servo’s have plenty of zip.
The 430L is the same one as supplied with the 450 SE V1 model and although as stated doesn’t have as much power as the 430XL motor supplied in the SE V2 has more than enough power for most fliers and most flying.
Ash’s comments on the supplied blades are quite correct from a performance perspective and I totally agree with him on this, however the supplied blades have proved to be very robust and give the model good stability at moderate head speeds so are a good option for beginners and sports flying, however for high head speeds and more 3D type flying then the Align Pro wooden blades would be a better choice.

It is amazing to think that what is really Aligns current entry level model is also capable of fairly extreme 3D flying out of the box and it is easy to start thinking critically about what could be improved on the model from a 3D perspective but for almost all potential owners no upgrades would ever be needed, it’s comforting to know that if and when their flying warrants it that there are a number of very cost effective upgrades which will help them to go even further with the model.

Bob Johnston
Align UK