Flight Test – Align T-Rex 500
After deciding that a T-Rex 500 was just the right size heli for him, Richard Budd found a good secondhand example and set about getting it just to his liking. Here he shares his experiences of living with this popular model from Align
Having had great fun with my 450 V2, I looked at the T-Rex 500 with great interest, first on the Internet where pictures and videos were posted and then again when the first kits started to arrive at the shops. I saw the 500 as a perfect size machine to fit on the back seat of the car and carry around in case you ever found some decent weather to fly. I originally thought that the 450 would fit that bill, and to a large extent it does, but the 450 is a bit small and prefers the calmer days or indoors.
The first time I saw a 500 fly was indoors, and I quickly decided that this is definitely more of an outside machine! My next encounter was the BMFA university challenge, where I was very impressed with how powerful and accurate the 500 was in stock form. As our technical editor, Colin grabbed the one for review, I had to wait until a chance comment at one of my local model shops revealed that they had just taken a secondhand machine in part exchange. A quick check over the machine showed that it had not done any hard work, had been upgraded and came with three servos and blades. A deal was quickly done and I took my new purchase home for a thorough check over.
Back on the bench, I had chance to have a good look at the machine. What I had just bought was a carbon fibre framed T-Rex 500 with stock motor and speed controller and belt driven tail. Fitted were three Futaba 9650 eCCPM servos and a Futaba 9257 tail servo. The extras fitted by the previous owner were: a metal tail box, metal bearing housings, metal washout arms and base, metal mixing arms a set of Align Carbon tail blades and a set of Align 430 carbon main blades.
I noticed a small crack in one of the carbon frames, and although some superglue would suffice, I decided that a change of frames was in order. This was no real hardship, as I was planning to do this anyway. Like many I read through the various forums, and one problem with the 500 which seemed to re-occur with alarming regularity was glitching caused by static discharge from the belt drive system. There were all sorts of remedies floating around, from grounding the booms to the frame and the negative on the batteries, to changing the belt drive to a shaft drive. There is even a company that is making static wicks and an ESD pate that grounds the belt to the frames. All this seemed a little complicated for my liking, so I went for the more simple option and replaced the frames with a set of RJX silver carbon frames which are a G10/carbon mix. There was a slight weight penalty for this, but the thought of no static problems far out weighed the few grams of added weight. Changing the frames was a little laborious – it would have been much easier during the construction, but the half hour frame change also allowed me to check that all the bolts had been thread locked properly.
Next on the agenda were the batteries. Now I had heard that some flyers were using the two T-Rex 450 batteries in series, and indeed, I do have quite a few 3S LiPos for my T-Rex 450, but I did not fancy that solution. Instead of 6S packs, I preferred the option of 5S packs. The main reason behind this was the acquisition of the new FMA 10S charger (review to follow) which would allow me to charge two 5S packs at the same time. So with an adequate power supply and four batteries, I could fly almost continuously. My credit card took a bit of a hammering again, and Aurorra soon had four Revolectrictrix 4200mAh LiPos sat on my doorstep.
Now at 465g each, these batteries are on the heavy side for the T-Rex 500, but I was reliably informed that they would be good for seven minutes of hard 3D and 10 minutes or more of gentle stooging around. they also brought the C of G onto the main shaft. I was also told that if I wanted some extreme power to complement the 5S arrangement, then I should look at the Scorpion 3206 – 1900 KV motor. It would seem that was not the only one being told this information, as this motor proved more difficult to find than Lord Lucan! I eventually tracked one down on the internet to Hong Kong and at £44 including postage; the price seemed quite good as well.
The motor arrived within a week and I fitted a 16 tooth pinion to it. Fitting was the proverbial piece of cake and the pre-fitted bullet terminals matched the standard align speed controller. The installation was completed with a Spectrum AR 7000 receiver and a CSM 720 gyro. Things were going well until I tried to fit the canopy. It would seem that the 420 5S pack and the canopy were not compatible! In truth, it could be made to fit, but it was then under a lot of strain. I had also bought a nicely painted Canopy FX canopy, which also did not fit over the battery. Salvation came from one of my local model shops, who had a fluorescent orange and white RJX canopy, which fitted over the batteries nicely. All I now had to do was set up the radio and go and fly.
I set the radio up to give me -5, 5, 12-degrees in normal mode and -12, 0, 12-degrees in all other flight modes. The throttle curve was then set to 0, 60, 70, 80, 100 in normal and 93, 83, 93 in flight modes 1 & 2. The tail rotor servo arm was set at 11mm and the gyro gain set at 75%. I left the speed controller with the standard settings which was soft start heli mode with no governor.
First flights at the field showed a very smooth, almost docile helicopter in normal mode, with the helicopter tracking nicely in fast forward flight and with the controls nicely balanced. I would describe it as a great sport model. Selecting flight mode one resulted in an audibly higher head speed and model that just came alive. Climb outs were just ballistic and collective pitch control was instant. On the negative side, I was not happy with the tail. Pirouette stops were bouncing and the tail had a slightly unstable feel at this higher head speed. I had experienced this before on my 450, so I thought that I had better try the same remedy. Consequently before the second flight I fitted a CSM 0.6 volt voltage dropper in the tail servo line. Subsequent flights showed that the tail was now spot-on and would hold no matter how much I tried to find the breaking point. I would love to explain why dropping the voltage to the tail servo (and thus slowing the servo down) would improve the tail stability and quality of the stops, but alas the answer is still eluding me!
With growing confidence, and this machine sure helps build your confidence, I tried every manoeuvre in my limited repertoire and then added some I had never tried before. This machine just lapped it up and never protested at the abuse I was giving it. So happy was I with this machine after only half a dozen flights, that I took it on my holiday too the RC Hotel in Corfu. I took the precaution of taking a large selection of spares and some 430mm Carbon blades from RJX to try out.
With four batteries, a charger that can charge two at a time, sun every day for two weeks and with every morning complete with no wind, I managed around 80 flights on this little gem in my two weeks in the sun! This allowed me to really get to know the machine. I have to admit, I spent almost all of the 80 or so flights in 3D mode and was treating the helicopter with scant regard. I did find that in the perfectly still conditions of early morning Corfu, that there was a slight control issue. I was struggling to achieve a straight loop without correction, flips required quite a bit of correction to hold them on station, climb outs resulted in wondering off forward and to the right and inverted hovering gave a noticeable trim change.
All of these issues were annoying, but not enough for me to worry about whilst on holiday. I simply decided that on my return to rain soaked Lancashire, I would fit a CSM CycLock which I have preciously used on other models with great success. Around flight 60, I also noticed that the helicopter and developed a slight whine, which was progressing getting worse. I traced this down to the top bearing on the Scorpion motor and noticed that the pinion was developing some play. 60 flights on the motor bearings can’t be considered to bad, especially as I had not added any lubrication!
As I had been pushing this heli hard, including having a go at this new ‘crack’ style of flying, I gave the machine a thorough check over. I was surprised that the only maintenance issue was a small amount of lateral play in the tail output shaft. This had not shown itself in flight and was quickly corrected with a 0.5mm shim washer. I did try the RJX blades, which I thought were an excellent all round blade and better at autos than the Align ones already fitted, but I elected to return to the Align blades as being lighter, they were a little more responsive and had more ‘pop’.
Back home I ordered a new set of motor bearings, and stripped down the motor when they arrived. I was shocked that my motor bearings were fine, but the motor shaft had been ground away where the top bearings sat on the shaft. I took some pictures and sent an email attaching the pictures and an explanation of what I had found, straight to Scorpion Motors in Hong Kong. Full marks on their customer service, as a replacement shaft and bearing arrived by registered delivery in less than a week. With customer support like that, I will not hesitate to recommend their motors to anyone else, and indeed I will be looking at fitting their motors and speed controllers on future projects.
Whist fitting the new shaft and bearings, I took the opportunity to add some bearing fit to help re-occurrence of this problem again. This repair to the motor gave me a chance to try the standard kit motor. This motor was adequate, but I missed the power of the Scorpion! I also took the opportunity to fit the CSM CycLock eCCPM control unit. As I have fitted a few of these now, the most difficult part was finding a suitable mounting position. I eventually settled on the underside of the receiver tray, which allowed access for programming whist giving me room to hide the extra cabling.
Three flights were all that was needed to ‘dial the helicopter in’ and the flight improvement and accuracy was worth the extra weight. Speaking of weight, my T-Rex 500 hits the scales at 1,880g, which is a little heavy, but it doesn’t seem to effect the performance.
In typical fashion, the transmitter was handed around the club and a number of people have had a go at this machine. In normal mode even relative novices enjoyed the smooth harmonised controls and stability, and in hooligan mode, all the more advanced pilots appreciated the flight characteristics and excess power this machine has. This heli has given me back some much needed confidence in my flying and my flying has improved beyond recognition as a result. This is partly because of the shear number of flights that I have put on this machine in such a short time, partly because of the shear power that this combination provides, but mainly, because spares are so cheap, that I do not care if I crash it!!
As always, I am always looking at ways to improve the helicopters I fly. With the hop-up parts fitted to this helicopter, I am struggling to find anyway of improving this little chopper any further. If I was trying to be critical (and lets face it… I usually am!). I would like a little bit more cyclic authority and speed. I have just purchased a set of SAB 430 Red Devil blades, and I may look at fitting some faster cyclic servos. I should also get around to adding some decals to that canopy… so watch this space!
The T-Rex 500 is available from all good model shops priced around £199. The UK distributors for Align models are Robbe Schulter UK (e-mail: firstname.lastname@example.org) and Skyline Models www.skylinemodels.co.uk
Tech Spec – Align T-Rex 500 CF
- Model type: Mid-size electric 3D
- Length: 850mm
- Height: 310mm
- Main blade length: 425mm
- Main rotor diameter: 970mm
- Tail rotor diameter: 200mm
- Motor pinion gear: 12T/13T
- Main drive gear: 162T
- Autorotation tail drive gear: 145T
- Tail drive gear: 31T
- Drive gear ratio: 1:13.5:4.68/1:12.46:4.68
- Flying weight: Approx 1700g