Align T-Rex

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Trex4b.JPG

T-Rex is the brand name of an RC model helicopter made by the Align Company. Align is a Taiwanese company that also makes home appliances and milling machine equipment.

There are several different versions of the original T-Rex, also known as the T-Rex 450, with various suffixes for different models that have come out since Align started selling it. Align also markets larger versions, the 700, 600, 550 and 500. There is also a micro version, the T-Rex 250. Since its introduction, this model helicopter has become one of the top sellers available. They are known for quality engineering and good value, also for attention to detail.

It is large enough to be flown outdoors in a light to moderate breeze but small enough to use relatively inexpensive components and to be flown in a sports hall. It is capable of more aerobatics than most pilots can perform but can also be managed by beginners.

Contents

T-Rex 450 Specification

A collection of Align T-Rex helicopters. Shown left to right are the T-Rex 250, T-Rex 450, T-Rex 500 and T-Rex 600
  • Length:660mm
  • Height:230mm
  • Main Blade Length:325mm
  • Main Rotor Diameter:700mm
  • Tail Rotor Diameter:150mm
  • Motor Pinion Gear:12T/13T
  • Main Drive Gear:150T
  • Autorotation Tail Drive Gear:106T
  • Tail Drive Gear:25T
  • Drive Gear Ratio:1:12.5:4.24/1:11.5:4.24
  • Weight(w/o main blade):450g
  • Flying Weight:Approx.730~760g

Kit list

  • X - original version, slightly shorter tail boom than the XL and no longer available.
  • XL - plastic version, available in:
    • HDE - plastic non-CCPM, mechanically mixed version
    • CDE - plastic CCPM version
  • SE - top of the range metal version with updated CCPM configuration
  • S - plastic version of the SE, frame available in carbon fibre or aluminium
  • SA - ARTF version of the S from Horizon Hobby
  • SE V2 - updated metal version (the gyro mounts under the boom, stock motor and ESC are higher rated, feathering shaft is thicker and head damper design is different)
  • Pro - new head, single piece narrow frame, torque-tube instead of belt drive for the tail
  • Sport - designed for stability and crash survivability, wider head, stronger blade grips, belt drive tail

The main difference between the X/XL and the later models is the X/XL uses bellcranks to connect the cyclic servos to the swash, while later models are direct-to-swash. The bellcranks have more slop, though they do have the advantage of putting less stress on the servos in a crash. The later models also use a sloped battery tray cantilevered off the upper frame, instead of mounting the battery on the lower frame as the early versions did.

A torque-tube consumes less power than a belt. But on a rougher landing when the tail blades hit the grass it can easily cause some gears to strip.

The success of the T-Rex has lead to many clones or derivatives from other manufacturers. Some examples are the Copter-X 450, the RC-Tek Diablo/Sky-Shark, and the Helidirect HDX-450. Debates about the merits of various models can be found on online forums.

Popular equipment

  • Align 430X brushless motor
  • Align RCE-BL35X 35A ESC
  • HS-65MG cyclic servos (HS-65HBs with karbonite gears are somewhat cheaper but may strip in a crash)
  • Futaba 9650 digital tail servo
  • Futaba GY240, GY401, or Logictech 2100T gyro
  • 2100 mAh or more, 20C or more, 3S lipo battery (e.g., Flight Power 25c 2170mAh, Thunder Power 2100 Prolite, or Air Thunder 2100)
  • 3amp switching BEC (most ESCs aren't rated for 4 servos with a 3 cell lipo, especially with a big digital tail servo; especially important with Spektrum receivers)
  • 5 or more channel receiver and transmitter with eCCPM
  • Low voltage alarm (such as Tranh's LiGlow), though the Align ESC's low-voltage cutoff works well, or you could just fly on a timer
  • Crash kit: any crash will probably require new main blades, feathering shaft, and flybar at a minimum, and possibly will strip the main gear as well.

Budget configurations can use cheaper servos and gyros (for example, the Telebee gyro and an HS-81 tail servo seems adequate for sport flying.)

Popular modifications

  • Most beginners prefer the wooden Align Pro 325 blades since they minimize crash damage. The stock Align "Carbon" blades in the low-end kits are not really carbon fiber and are pretty heavy.
  • Carbon blades (Radix, V-blades, etc)
  • Many people prefer the V1 feathering shaft and build "V1.5" helis by mixing and matching V1 and V2 components (V1 head, V2 tail)
  • Replace the stock aluminum ball links with stainless ball links, as the Al links wear faster and may develop slop
  • Early versions of the S/SA used plastic tail rotor belt drive pullies which were prone to failure. Later versions of the kit use a metal pulley on the frame side but are still plastic in the tail. This can be replaced with Align HS-1203; the frame side metal pulley is HS-1216.
  • The governor mode of the stock Align ESC is not well-regarded by many; higher-end ESCs are often substituted (the Castle Creations Phoenix-35 is popular.)
  • Other brushless motors are often used: for example, Scorpion HK2221-8, Medusa 28-40-3400, NEU 1107-2Y.
  • One interesting option is an all-belt frame from Accelerated RC which eliminates the main gear completely.
  • Scale bodies available from http://darthdrk.4t.com/
  • Gorilla gear landing gear

Setup tips

  • The excess plastic on the 450S canopy can best be removed by carefully scoring along the mold line with a sharp hobby knife multiple times until the plastic will break cleanly when flexed; this method is much cleaner than using scissors (from the Finless video referenced below.)
  • The 450SA manual at the Horizon Hobby website has some good pointers for how to install the servos and run the servo leads to the back of the frame.

Resources

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