On 26 Sep 2005 18:14:12 -0700, "nrp" wrote:

Some random points on props:

A prop is highly stressed and will grow in diameter almost 1/8 inch at
takeoff due to centrifugal forces - whether steel, aluminum, or wood.
(Does that get your attention?)

Indeed, especially when standing a little bit in front and a little
bit to the side of a 600 horse R-1340 or PT6A running at cruise rpm
with a C-H Strobex in my greasy mitts. Had an turbine Air Tractor
climb the chocks once-guy driving it was a sharp cookie-had the
throttle back before it came down the front side of the chocks...

I understand it takes an A&P signoff just to paint or touch up a prop -
even on the black backside.

I wasn't around when standard terminology was defined, but the "back"
of a propeller blade is the cambered side-typically painted with white
tips and a mfg's decal, and the "face" of a prop is the relatively
flat (and matte/flat black) side that "faces" you when you sit in the
driver's seat of a typical single with a tractor-type prop.

A Mil Spec manual somewhere showed that anodizing reduces the fatigue
strength of aluminums about as much as shot peening can increase it.
They must do anodizing for other reasons - maybe to provide some
corrosion resistance?

Yup. Been too many years, but am thinking that Sensenich fixed-pitch
and older Brand M blades get grey-anodized. The local prop shop had a
way-cool "T"-shaped anodizing tank made. Fixed pitch props were hung
in the solution of the bus bar horizontally, the c-speed blades
vertically.

From personal experience, the right prop guerrillas can do a remarkable
job getting a prop to run right - at least fixed pitch ones.

Agreed.

TC