# Colletive pitch measurement for micro CP heli

I wrote a simple Microsoft Excel spreadsheet which calculates the collective pitch with trigonometric function.

pitch2e.xls : Microsoft Excel spread sheet

pitch-e3.pdf : quick char tfor Nano CPX, MiniCP, mCPX BL, V120D02S, 130X and T-Rex 150 DFC.

How to measure:

(1) Align each main blade right angled (90 degree) to the grip. Tighten the drag bolts firmly. Then measure the distance from the center of the drag bolt to the blade tip end. It is 138mm for Blade 130X.

(2) Set the pitch curve 0-50-100.

(3) Move the throttle stick to 50%. The two main blades should be in a straight line. They show zero collective. If they are not in straight line, adjust the three push rods from the servos to the swashplate. Measure the height of the blade tip. Let us assume that it is 80mm above the table top. The ruler must be right angled to the blade and fixed for the following procedures.

(4) Move the throttle stick to 0%. Measure the height of the blade tip. If the tip is 50mm above the table top, the travel is 30mm.

(5) Move the throttle stick to 100%. Measure the height of the blade tip. If the tip is 115mm above the table top, the travel is 35mm.

Now calculate the pitch.

Excel formula:

=DEGREES(ASIN(Y/X))

X=blade length
Y=travel

The estimated pitch is 12.6 degree for 30mm travel, 14.7 degree for 35mm travel.

last updated: Jan. 9, 2014