FAQs

The frequently asked Trex questions :

Q. What servos should I use?
A. Any micro servo capable of delivering 1kg/cm or more of Torque. Speed is also a factor, under 0.16 sec for 60 degrees of travel would be OK for cyclic or collective. Tail servos should be faster but don't require as much torque, generally 0.1 sec for 60 degrees of travel is acceptable. TrexTuning recommends the Hitec HS65 MG for cyclic and the Futaba 9257 for tail.

Q. What speed controller should I use?
A. This depends on motor choice, the majority of people will be fine with a 25A ESC. However, if you intend to run a 3S lipo and go for maximum motor performance (450TH perhaps) then a 35A ESC would be preferable as current is likely to be at or above 25A. Also make sure that your ESC can run a 3S lipo and the required 4 servos current draw. The Align 25A and CC 25A both state that only three servos are supported in a 3S configuration.......nobody has reported any failures due to running 4 servos.

Q. What is the best motor for 3D?
A. This changes with time as more motors come onto the market. One of the most popular motors is the 450TH which produces good perfromance at a budget price. This question again comes down to personal preference, please reference my motors page for more specific motor comparisons.

Q. My cyclic controls seem to be stiff, what should I do?
A. Put a drop of oil on the centre swashplate ball. Others have reported success with heating up the swashplate centre ball with a soldering iron to loosen it up. This could also be stiff ball links (try squeezing ball links gently with pliers to loosen them up). Another common build error is to over tighten the collective rocker screws. See my build instructions for details. Check that the washout arms and mixers are not over tightened. Lastly check that the ball links on the swashplate can rotate freely, this helps with the new purple coloured ball links which are a much tighter fit.

Q. My Trex tail is uncontrollable, what's wrong?
A. You may have mounted your gyro incorrectly see if it is the Align gyro as the instructions are incorrect. My build instructions show the correct mounting of this gyro. It's possible you have over tightened the ball links on the tail pitch slider, they should be able to rotate freely.

Q. What lipo should I use?
A. See my lipo page for a list of recommended packs for the Trex.

Q. My Trex is hyper sensitive to cyclic controls, what's wrong?
A. See my build instructions on correct setup of servo throws. The Trex does have very sensitive cyclic, I also add 30% exponential to dumb down the cyclic as well as using the inner most servo horn holes.

Q. What pinion should I use for motor xxxxxx ?
A. See my motors page for recommendations of pinion for most common motors used in the Trex..

Q. I have a lipo, what charge rate (amps) should I use?
A. In general it is safe to charge at 1C (e.g for a 2200mah pack this would be 2.2A) Using lower charge values can prolong the life of your pack, 1C charging generally charges your pack in approximately 1 hour.

Q. I have full throws on the collective but my Trex doesn't seem to have enough negative pitch?
A. Elongate the slot (that limits the travel of your collective rocker) by 2mm at the bottom, this should give you the extra few degrees you need for 3D inverted punch outs.

Q. What is the 'stretch kit' ?
A. This is elongated blades 335mm and a longer tail boom and belt. The longer blades allow for a lower headspeed and disc loading. Early reports are that for 3D the larger blades need more power than the standard ones in the kit.

Q. Do I need a heatsink for my motor?
A. If it is getting hot to the touch (or burning hot) then yes. In general heatsinks are good for all electric motors as they take the heat away from the magnets and windings allowing for a more efficient run. Heatsinks will also potentially elongate the lifespan of your motor.

Q. My lipo is hot after flying, is this a problem?
A. In general most lipos are safe for 140-160 degrees Fahrenheit. Above this temperature and you could be damaging your pack or have it explode due to discharging above it's 'C' rating.

Q. What headspeed should I use for my Trex?
A. 2400rpm is generally accepted as a good head speed for a nice smooth flying Trex.

Q. My main gear that drives the tail belt gear doesn't line up properly, is this a problem?
A. This is normal, some gears line up perfectly, others don't. It has not caused a problem.

Q. How tight should the tail belt be?
A. If you pinch the belt it should be possible to almost make it touch itself. The Trex belt drive saps power if over tightened.