The frequently asked X400 questions :

Q. What is better X400 or T-Rex?
A. This is always going to be a matter of priorities and user requirements. The X400 is a higher quality machine, fit and finish is better, there is no slop in the controls and it is extremely good straight out of the box. The X400 has all metal frames and generally feels sturdier built. The X400 is also more stable than the T-Rex and therefore more suited to a beginner. The T-Rex is far more 3D capable straight out of the box plus the plastic side frames can be modified to lose all important weight. The T-Rex is more mature in the market so there is a thriving number of upgrades dealers and easy access to spares as well as advice and guidance on setup.

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.

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 (AON 2815-3500 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. Tough question as there is little data to go on right now. However, if we are to assume that motors that work well in the T-Rex will also work well in the X400 then for 3S the AON 2815-3500 is a great motor. For 4S or more the Mega series of motors are a popular choice. Please reference my motors page for more specific motor comparisons.

Q. My cyclic controls seem to be stiff, what should I do?
A. This is not as prevalent a problem on the X400 as the T-Rex. However, it is still possible to get stiff links ball links on the X400. Gently squeezing the link (whilst it is still on the ball) with pliers should loosen up the link. Check all links in your control system to make sure they are loose enough to rotate under the weight of the control rod.

Q. My X400 tail is uncontrollable, what's wrong?
A. Either the tail ball links and pitch slider is too stiff or the gyro or tail servo are configured incorrectly. The build section contains information for achieving a smooth running tail pitch slider. Refer to your gyro instructions for correct operation of your gyro.

Q. What lipo should I use?
A. See my lipo page for a list of recommended packs for the X400.

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 X400..

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. 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 X400?
A. 2400rpm is generally accepted as a good head speed for a nice smooth flying X400..

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 X400 belt drive saps power if over tightened

Q. Can T-Rex parts and upgrades be used on an X400?
A. The X400 rotor head is quite significantly different to the T-Rex so for the most part items are not interchangeable. The tail rotor is very similar to the T-Rex and so some parts may be useable, for instance upgrade tail pitch sliders.