MAIN ROTOR SYSTEM

( Click on images for a better look )

These are the tip weights for adding inertia to the main rotor system. One each is installed inside the outboard ends of the main rotor blades and weigh about 5.1oz each. Builder just has to saw them apart from one piece, and drill the holes.

Here's a trial fitting of the main rotor blade straps. The factory specifies that wood filler blocks between the straps have to be carefully sanded to a thickness of 2.250". Although Homer told me he likes them to be about 0.010" thicker at 2.260".

I was apprehensive about taking a hacksaw to my, presumably, very expensive main rotor blades to chamfer the root end. But the prints are very explicit as to dimensions. I measured and cut each side seperately. It was actually a non-event.

Another shot of same. Interesting pattern for the fiberglass doublers. I'll have to ask Tom Smith what the significance is for this double lobe pattern. The wood blocks at the root end of the blade are specified as needing to be 2.250" thick. Mine are 2.260" so I'll need to remove 0.005" of material from each side.

And yet another shot, but this one clearly shows the lead/lag pin. It was unclear during my Phase One main rotor blade installation demonstration as to how the aligner block adjustment screws tweaked the MR blade lead/lag. Now I know, the screws actually push this pin laterally which causes the blade to pivot about the 9/16" inboard strap bolt.

This is one of the main rotor blade outboard end caps. A giant PITA to fabricate! Good thing I thought ahead and bought extra wood stock during my Rotorway Phase 1.5 trip!

I added a redundant main rotor RPM sensor. The original sensor, which is connected to the dual tach on the instrument panel is just visible in the back. The sensor in the foreground will be connected to my supplemental guage computer to correlate the main rotor RPM with the tail rotor RPM. Any indicated divergence means tail rotor belt slippage. I will probably also implement a low rotor RPM horn. Both sensors sense the same magnet bracelet.

When locating and gluing the blade straps to the main rotor blades, the specified dimension between the 9/16" thrust block bolt and the leading edge of the main rotor blade needs to precise, and identical on both blades. The Rotorway recommended method for acheiving this accuracy struck me as fraught with possibility for error. So after talking with a number of other builders I decided to improvise. If you look closely you can see the measurement on the micrometer.

The desired dimension between the center of the 9/16" thrust block bolt and a line extending from the leading edge of the rotor blade is basically 1.9875". This dimension minus half the diameter of your specific 9/16" thrust block bolt, is the dimension between the surface of the bolt and the surface of the straight edge. In my case, this turned out to be 1.707". So I simply fabricated a gauge pin from 1/2" cold rolled steel rod, and cut and ground it to the proper legth, within about a half thou.

When it comes time to glue my blade straps down, I'll simply insert the guage pin into the pitch pin bearing hole, against the 9/16" bolt in the thrust block (shown here), rotate the thrust block such that guage pin is facing the straight edge, then pivot the blade straps on the outboard 1/4" bolt so that the guage pin is square and snug against the face of the straight edge. I'm then assured of an accurate and repeatable dimension between the two surfaces without fumbling with a dial caliper or telescoping guage while my hands are shaking because I'm about to commit my expensive rotor blades to the glue!!!! Thus, I should be well within the required 0.005".

This shot shows how I used my custom gauge pin (top circle) that I fabricated to hold the dimension between the leading edge of the rotor blade and the center of the 9/16" thrust block bolt. I just dropped one bolt through the straps and wood blocks, to allow the straps to pivot relative to the wood blocks, held the straight edge against the gauge pin and adjusted the lead/lag bolt (bottom circle) until there was no daylight visible between the straight edge and the leading edge of the blade. Once this was achieved I reamed the remaining bolt holes, installed and torqued the bolts and presto!! Worked great! Took a lot of the struggle out of it, although it still took two sets of hands and eyes. The pitch horns are only temporarily installed here to allow proper thickness for the bolts that are holding the inboard end of the straps and thrust blocks together while the glue sets.

Here I'm locating the tip weights on the underside of the main rotor blades prior to drilling and countersinking.

Here's a shot of the ship right after hanging the blades for the first time. My friend Craig Hook is on the ladder.

What I intended to capture here was showing how the weld fillet around the blade strap "spine" can hold the pitch horn off from lying flat against the blade strap. The fix is to file a chamfer in the bottom corner of the pitch horn.