Du-Bro Whirlybird 505 Pitch Gauge - What Pitch Is Best?

I am in the process of rebuilding the head of my Du-bro Whirlybird 505 and need a pitch gauge to properly set the pitch. Fortunately, v22chap posted pictures with dimensions on runryder here.

I have converted the pictures to a full-size PDF drawing, for anyone else who is fortunate enough to get one of these historical models.

So my question is: "What pitch should I use?" - I put the dimensions on the drawing for 5, 3 and 2 degrees of pitch.

Apparently, the original instructions had 5 degrees. However, I understand that a higher head speed should help with stability (makes sense) and also will probably help with some improved control (which the model needs). Others have changed their pitch to 3 degrees to make the necessary improvements to head speed.

Should I go to 2 degrees to get even more head speed? Or will this not create enough resistance to the opposing spin of the motor and cause the heli to lack the lift to take off? Is the original 5 degrees best? I am sure Dave Gray did extensive testing prior to deciding upon 5 degrees for the original kit...

I appreciate any insight that can be shed on this choice!
Thanks!

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Attached Files

Du-bro Whirlybird 505 Pitch Gauge.pdf (15.2 KB)