Pitch setup…without a gauge.

I bought my TRex for Christmas 2005 and realised I couldn’t accurately measure the pitch because my full sized pitch gauge was just too big to fit the small blades. However, a bit of lateral thinking, and looking at what was available in the tool box, I came up with a cunning plan!

You can apply this method to any heli as most manufactured in the last few years will allow roughly plus to minus 10 degrees overall collective pitch range, and this is more than sufficient to allow full blown 3D flying.

The key to getting a heli to fly properly is to set the pitch so the helicopter will hover comfortably. Some people, including me these days, like to have the hover point at the 75% stick position. Others will want the traditional 50%, mid stick hover position. The secret is to have a known MECHANICAL value at the 50% stick position that you can then adjust electronically in the transmitter to suit your own style of flying.

I always recommend that you follow the manufactures guidance to adjust the push rod lengths to achieve what they probably describe as a 3D or aerobatic flight setup. This is because what we want to achieve mechanically is 0 (zero) degrees pitch at the mid stick position. Once done, it’s simple to work out other pitch values!

Therefore, in Normal mode, you could program the bottom point of the pitch curve to 25% and know that it will yield - 5 degrees, give or take a degree or two. Program 75% at mid stick will give + 5 degrees (Most helicopters will hover well at about + 5 degrees pitch), and the top point will yield maximum pitch, about 10 degrees.

Having set these points, you can then adjust the throttle curve values to make sure the heli hovers at your desired stick position!

With me so far?

Work with one blade at a time. Mark the blade you want to work with, and also mark the relevant pitch rod. (I use a bit of insulating tape on both). Then remove both blades from the rotor head.

I found a six inch metal engineers ruler in my tool box, just a few quid from the local hardware store. Next, lay the ruler at its mid point on the flat inside surface of the marked blade grip.

CAUTION, if you’re doing this with an electric heli, disconnect the motor otherwise you’ll be in a world of pain!

Turn on the transmitter followed by the receiver, and set the pitch lever to the mid point. Then looking at the edge of the ruler see how far it’s out of line with the fly bar. Now, using the pitch lever on the tranny, adjust the pitch until the ruler lines up with the flybar. (This will give you a good idea how much adjusting of the pitch rod is needed and it what direction).

Next, re-set the pitch lever to the mid stick position and adjust the pitch rod until the ruler lines up with the flybar. This is the same process you’d use to set zero degrees with a pitch gauge. You’ll now have one blade adjusted to exactly zero degrees! Repeat the process with the other blade grip, and you’re ready to fly! If you got it spot on, you’ll also find the blade tracking is perfect. Now program your transmitter to give the Normal pitch curve you want. Idle up 1 and 2 will already be set as 3D curves giving maximum negative pitch at bottom stick, zero at mid stick and maximum positive pitch at top stick.

Final adjustments can be made to both ends of these curves when the heli’s in the air. Basically, if you have full throttle at top stick and the engine “bogs down” when you give it full collective, you have a bit too much pitch at the top. (Assuming the engine’s running properly). Try setting the top pitch point in your tranny to 98% and try again!