T-Rex 700L Dominator

Hey there !
It's been a while since the last article... So let's talk about something big this time. something really big. REALLY. The T-REX 700L Dominator, a class 700 (rotor size of about 1.6m, 5kg) helicopter made by Align. If you remember, I started to fly helis with an other Align helicopter, the T-REX 450 Sport V2. We remember beeing very afraid of it when the rotor started to spool up for the first time. Let me be clear, this T700 has NOTHING to do with it.

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So, from a technical point of view, this 700 heli is the most advanced version of the T700E, first 700 electric heli made by align of this side. It features the last upgrades of the frame, BL815H and BL855H brushless servos, the 800MX Align motor, a Castle Creation 120A ESC and the DFC rotor head. The stabilization control is done by the new GPro controller (formerly known as 4GX)

IMG_8212Disassembled DFC head

IMG_8221The Cyclic BL815H brushless servomotors

IMG_8219The huge 800MX Align motor.. A real monster !

The built is really straighforward and you just have to follow the manual :). Beware to threadlock all the metal-to-metal screws and VERIFY it's well locked ! I crashed because a servo screw became loose... πŸ™

IMG_8215The frame beeing assembled

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As I said, it comes with the latest "inovations" from Align, so you have two helicoidal gears wich make a really nice sound once in the air πŸ™‚
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IMG_8230the DFC head

IMG_8225Close-up view of the motor and servos

IMG_8232Almost ready to fly here

IMG_8228Tail and servo tail

IMG_8916View of the implentation of components

As I didn't have (still don't) a High Voltage receiver, I had to think a little about electronics in this bird. This is the wiring I used to power the servos with HV source (2S lipo = 8.4V fully charged), and feed the receiver with a safe 5V.
Electro_T700Electronic wiring

The BEC component is actually in the T700L Dominator kit, good point for Align (again) :-D.

IMG_8908Tail assembly details
One word about the CC 120A ESC. When using lower head speed (<1800RPM), the CC tends to get very hot (above 100Β°C). This can lead to the destruction of the device. I wanted to put a 1500RPM head speed at first but changed my mind after seeing that. 1850RPM works fine for me. As you can see in the next picture, I put the controller on the rear of the frame, which is excellent in terms of heat because we have a giant propeller above it that helps to cool it down πŸ™‚ IMG_8904

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Setting the GPro up is really a piece of cake, we can see Align really cared about the ease of use for this device. It comes with a free software for PC, Android and Iphone users! Note that for the phones, you have to buy a BlueTooth device separately.

IMG_8917GPro unit

As I could expect, it flies REALLY well, and the FBL head is quite amazing at all head speeds I tried (from 1500 to 2100).

Stay tuned ! More posts will come soon.. I hope πŸ˜€

Align's T-REX 450 Sport v2

Ok, so after flying with our quadrirotor, I wanted a machine capable of doing a more aerobatic flight. So I started looking at CP helicopters. A CP (Collective Pitch) helicoptere is a particulare type of heli that is able to independently move its blades. For instance, the two blades can take a positive pitch which will sustain the helicopter in the air, or it can give a different pitch (Called cyclic pitch) regarding the position of the blade, to make the helicopter move in a particular direction. See this Wikipedia page for more informations about it.

So, after a while, I decided to buy a class 450 heli (rotor diameter around 700 mm), mainly because of the low price of this class and also for the ease of use (and also, it's less dangerous than a 700 with a rotor diameter of 1m50 !). I bought the TREX 450 Sport V2, as the Align brand has a really good reputation among the Internet.

The box arrived 10 days after shipping, and my first impression was : that's a very tiny box !

Everything inside this box is tidy.

Let's open all those sub-boxes, to discover that there is a significant number of parts πŸ˜€

One great point with this kit, is that it comes with the electronic (motor, ESC, servos) and i had to add my newly converted to 2.4Ghz Eclipse 7.

Let's now have a look to the assembly. I knew what to expect here has I read a lot of things on the Internet about it. Clearly Align masters the subject and the assembly is really straightforward.You just have to follow the manual. Don't forget to double check if the pre-assembled parts are well threadlocked.

Head assembly

This is clearly a masterpiece, it's beautiful and there is no backslash. the only (related) problem is that the links are tight so you have to lapp the plastic screeds. Here again, it's really well documented on the Internet. On the pictures, you may have noticed that I inverted the main shaft. Be careful or you'll have a big backslash between the frame and the head.

Let's now have a look on the carbon frame assembly.

Nothing to say here, just follow the manual :-)Oh, just, don't threadlock the rear screws (where you insert the tube) as we'll need to loose it to put the tube and adjust the tension of the belt.

Let's focus on the AC assembly. Almost nothing to do here for me as it was well locked from factory.

A little word about the main gear : to adjust the backslash between the motor and the main gear, one tip is to insert a piece of paper between the teeth, so there is around 0.1mm between them, as given by Align.

Last part of the job before the adjustments : the electronic. Just screw the servos, make them horizontal when the TX is at neutral, and it's done ! Also put a little strip of foam between the frame and the gyro to absorb vibrations.

Annnnnnd it's done : it took me two days to do it, but it was the first time I did it ! I think I would take 5-6h now to assemble it again.

Later we'll talk about the first flights, maintenance, and the first crash I had after 50 flights ! Stay tuned πŸ˜‰