Building Masters For A 1/48 SEAWOLF Pump-Jet, Part-3

Well, after a false start, explained below, I have finished assembly of the blades onto the hub of the rotor master. When I get done banging this report out I'll go back and build up Evercoat filler filets to the root of each blade, then on to construction of the ring that girdles the tips of the blades -- pretty much in the fashion that we see a supporting ring around the tips of a 688I submarine propeller. I'm told that this ring, on the SEAWOLF, sits within a recess in the shroud. I've also learned, just yesterday, that this propulsor has a six bladed rotor, so that information in came in the nick of time ... whew!

I got a problem to address coming up: My machine lathe does not have the height over bed to permit machining of the big diameter shroud master -- looks like I'm going to have to adapt my wood working lathe to do the job. Shit! It's cold in the shed this time of year and the lighting is horrible.

What a cruel and unforgiving world we live in!

David, Cast white metal rotor and stator blades over the 1/48 drawing I used to loft measurements from. Upper left you see the three rubber tools used to give the molten metal form as it changed state from a molten liquid to a solid.

My first attempt at the rotor master failed because I failed to plot the height of the mean cord point at the tip. As a consequence the rotor had blades with a negative rake angle - I screwed up big time, wasting over six hours of work. What a dumb-ass! Anyway ... this shot does show how I used a blade alignment jig to position the initial blade onto its hub. My only excuse: It was three in the frig'n morning and I plowed on without checking the plan after the first blade went down. Shit! What a dumb-ass!!!! One cast metal blade was trimmed so its root butted up against the face of the installed hub, this became a template used to mark off the outline in which I would route out a hole to fit the base of each blade. By projecting a portion of a blade into the hub I insured a tongue-and-groove fit that would resist breakage later as the assembled rotor was worked further.

I'm skipping ahead a bit here to show you the wrong rotor, on the right, and the replacement one I just finished this afternoon. Ouch! See what I'm talking about? The good one has a zero rake angle (displacement of the mean cord line either forward, or aft or center as in this rotor, of the plane perpendicular to the axis of rotation). The metal blades were adhered within the hub with CA adhesive, using baking soda as a grout filler/accellerator.