Mountain Piet II
John Dilatush's Pietenpol, firewall forward...
revised June 27, 2003
Let's take a closer look at the front end of this bluff-nosed bird! Most obvious here is the prop, which John hand-carved from two Southern Ute Indian canoe paddles (just kidding about the canoe paddles, but John did make the prop himself). John wanted to turn a wood prop the same RPM as the Ford 'A' Piets so the prop, redrive, and operating envelope are all based on retaining the original Piet speeds and RPMs. Behind the screened intake on the nose of the Mountain Piet lurks the belt redrive that John designed and built himself. Remember that the Subaru is water-cooled, so the cowling and intake didn't need to be built with cooling air intake in mind... John did a good job of enclosing the redrive while still creating an antique/classic airplane appearance this way. And drag is not an issue with the Pietenpol, since speed is not the objective ;o)
Port side of the engine cowl showing the big exhaust out of the turbocharger, as well as that intriguing intake along the side of the fuselage. Engine thrustline was moved a bit off of the top of the top longeron, based on knowledge of typical Piet behaviour when the power is backed off.
Starboard side of cowl... simple and clean. Note thrustline slightly above top of the top longeron/part line.
Runup! John fired the beast up and lifted the tail with a quick blip of the throttle. The engine started instantly, idled as smooth as butterscotch pudding, and the overall sound was very pleasing to the ear.
Wing tiedowns made from simple straps at the wing strut attach points. John has made the strut attach fittings a tad longer to make it easier to get the bolts into the fittings. Fittings made exactly to Mr. Pietenpol's 1929 plans result in very tight spaces for the bolt head, washer, and nut to be installed and tightened.
Aileron control horn, using the "motorcycle chain link" cable clevis connection. John constructed all the control horns exactly per the 1929 drawings.
Jury struts, with a very nice connection detail at the struts. Most builders use the Adel clamp method to secure the jury struts, but John has welded in short sections of tube to provide mounting bosses, and used eyebolts as the attach points.
Ah, the empennage! While this looks like an ordinary Pietenpol setup, note the elevator control cable geometry. John moved the bellcrank up from the stock location in the fuselage area behind the pilot's seat, resulting in equal-length parallelogram sides (remember your high school geometry?) as the bellcrank and elevator go through their travel. What this means is that the elevator control cables retain their tension and the top cable doesn't contact the leading edge of the horizontal stabilizer when the plane is sitting on the ground and the control stick is let go. And of course this photo shows two concessions to modern construction technique: aircraft cables with Nicopress sleeves instead of wire braces with wrapped ferrules, and a tailwheel rather than a skid (but still using the fork and spring per plans).
Oh, yes- about that mysterious control lever in the cockpit. It connects to this towhook at the tail. Yes, it's used for towing sailplanes aloft... but don't try this at home with your Ford 'A' Pietenpol! "Mountain Piet" is one muscular little experiemental!