Aviation From My Rocking Chair: Wood, You Say?

Greetings again, Troopers.

As you may have noticed in last month’s column, I completely avoided writing about Wood propellers. That was by design as I needed enough material for two of these exercises in correspondence (and for me, trepidation).

Let’s talk first about advantages and disadvantages of Wooden propellers, then I’ll list some of the practices that should add greatly to the service life of your prop, and finally we’ll cover a little about prop performance.

Advantages:

1. Light weight and increase in payload. 2) Lower cost.

2. Will operate reliably at higher RPM (up to 6000 RPM) 4) Very low possibility of failure due to fatigue. 5) Can be constructed by amateur builders. 6) Damps engine vibration far better than metal props. 7) In case of a prop strike, the wooden prop itself will be destroyed, but in most cases, there will be no damage to the engine crankshaft.

Disadvantages:

1. Can warp if not properly maintained.

2. Can decay if not properly maintained.

3. Easily splits when FOD is encountered.

4. light weight can cause rough running with some four stroke engines due to less flywheel effect. 5) Performance not equal to metal props due to thicker sections required.

O.K., let’s press on with things that will extend the service life of your wooden propeller: 1) Check prop attaching bolt torque at least every 50 hrs per manufacturers data. More frequent inspection is necessary when climatic changes are extreme such as change of seasons.

2. Store propeller in a horizontal position and cover with a waterproof cover if exposed to weather. 3) Do not use the propeller as a tow bar to move your aircraft.

3. Protect your propeller from moisture and UV exposure by waxing with an automotive type of paste wax at least once a year. Be sure to keep blade tip drain holes clear.

4. Avoid run up areas containing loose stones and gravel.

5. Finish loss on the leading edge is a normal wear item, and is dependent on the amount operation in rain and grit.

6. Touch up worn finish and scratches with spar varnish. Check with manufacturer for wear and scratch limits.

7. Inspect often for bruises, scars, and other damage to wood and blade leading edge protection. 9) Assume your propeller is un-airworthy after any kind of impact until it has been inspected by qualified personnel.

8. If you have any concern about damage on your propeller, contact the manufacturer for limits.

Don’t fret y’all. I’m just about done. It’s time to select that prop for the performance you need.

Standard Pitch/ Normal Flying. For normal or cross country flying. A fixed pitch prop that turns between rated engine RPM and 50 RPM over rated at full throttle at sea level.

Cruise Pitch. A cruise propeller will turn 50 to 100 RPM under rated engine RPM at full throttle level flight. Note: While cruise pitches will provide 4-6 mph higher airspeeds at cruise power rpm, maximum level flight speeds are no better than Climb or Standard pitches and takeoff and climb performance will noticeably suffer. Climb Pitch/ High Altitude Operation. Improved takeoff and climb performance requires a propeller that will turn 100 to 150 RPM over rated engine RPM at full throttle and level flight. Climb pitches will typically reduce flight speeds by 4-6 mph at cruise power RPM’s. A climb pitch is also recommended for aircraft operating from high density altitude runways.

Well, my friends, that is it for another month, and since all this typing has erased my finger prints you won’t even know who wrote it!

Rick Vaux TC4130