page 47-07: setting propeller pitch

The propeller pitch is set by loosening the six bolts shown going through the front prop bulkhead into the hub, twisting the blades by hand, then re-torquing the bolts.  This obviously is an imprecise, trial-and-error process, made worse by the fact that the act of bringing the bolts up to the proper torque causes a very slight rotation of the blades.  The build manual says to set each blade to a specified angle within plus or minus 0.1 degrees (!?).  This is to be accomplished using a supplied steel bracket placed at a particular radial position on each blade and a digital level with a magnetic base.  The prop is leveled horizontally and the level is referenced to (zeroed on) the longeron.  Sensenich supplies different diameter metal "pegs" that are to be inserted into a hole in the hub to set the pitch to three different common angles but Van's says these can be off 0.7 degrees and therefore shouldn't be used.  

Here's the problem: The commonly available digital levels, most of which advertise accuracy of plus or minus 0.1 degrees, actually deliver this accuracy (if you read the fine print) only near 0, 90, 180 and 270 degrees.  Otherwise, it's 0.2 degrees, and I doubt it's actually that good.  

Since having each blade at the same angle is far more important than the actual angle itself (as long as you're close to the desired angle), I decided to use the laser built into my level to project a line on the floor (hard to see on the blue tape).  

My procedure went like this:  Use Van's procedure to get as close as the digital level will allow to the prescribed pitch angle for the first blade, mark the laser line on the floor, rotate the prop 180 degrees, transfer the bracket and laser to the second blade, twist the blade until the laser line is on top of the mark for the first blade.  Tighten. Tweak. The blades are at the same angle.

Off topic:  For the past nine months I've been having a house built in the hills west of Loveland.  There's lots of wildlife there so I've had a trail cam set up in the back yard (you can see the house in the distance).  During the cold months elk come down from the high country and hang around until spring.  Here's one pic.  My neighbor who lives about 1/4 mile away trumped it by showing me several video clips of two mountain lions at once in his yard.  Another neighbor had two moose in his yard and a bear rummaging through his trash can,  Ah, life in Colorado.