wooden props, pros or cons?

[Brad W]

I was looking casually the other day at a couple of old classic taildraggers...namely an Aeronca Champ and a Cessna 140. The 140 had a wooden prop.

My initial reaction was not for me... based on the hangar waiting lists around here, I doubt if I'll ever see a hangar to store anything in.

Then I realized, I've never flown an airplane with a wooden prop, at least that I remember....and I really don't know how durable they really would be outside. I don't know anything about the proper care and feeding of them.

I suppose covers could be made or bought, and that would protect them somewhat...but then again covers might also trap in moisture.

either way, clearly they would weather and need refinishing often... but how often?

and is that something an owner-pilot can do or does it demand A&P's and sign-offs?​

And what would the pro's and cons list look like beyond that required care and maintenance?

I imagine the wooden props are lighter.​

I imagine the shapes and thicknesses for wooden props are different than what could be had in aluminum... are wooden blades generally going to be thicker?​

what else?​

 

[kmacht]

With modern urethane finishes, storing a wooden prop outside isn’t detrimental like it was decades ago. If buying a new wood prop, many manufacturers also offer an option to have the wood encased in fiberglass or carbon fiber. Prop covers that zip on and off are also rather inexpensive from places like Bruce’s custom covers. I wouldn’t shy away from an airplane just because it has a wood vs metal prop.

 

[kyleb]

Wooden props are typically smoother running and are definitely much lighter than metal props. They typically have thicker cross sections and are less efficient. The easiest performance boost for a 65 horse Continental airplane (other than an engine swap) is to move to a metal prop. Would I want to park on on the ramp for an extended period? Probably not. If the finish fails and the underlying wood gets moisture damaged, a new prop may be in your future...

 

[Daleandee]

As stated above wooden props are generally smoother as the wood absorbs engine pulses and vibrations better. I fly a Sensenich wood prop on a six cylinder engine in my experimental and it is very smooth. Mine has always lived in a hangar. I clean and spray wax it when cleaning the airplane post flight. Still looks great.

Wooden props aren't great in the rain although brief periods aren't a problem. I've been caught in light rain a few times and have found no damage but mine does have leading edge protection on it.

One big positive is the great look of a wooden prop!

 

[Brad W]

oh, I hadn't thought of that....flying in the rain and the potential for erosion.

..... many manufacturers also offer an option to have the wood encased in fiberglass or carbon fiber. ....

that makes me think of this stuff I bought for a project a few years back. A penetrating epoxy product sold primarily for marine applications. I see it's called "smith's CPES" now, but I don't think it had the "Smith's brand name when I bought it.... No mater though
This was some very low-viscosity stuff and was extremely slow cure.
Something like this, if it didn't negatively change the stiffness and weight, could be game changer for weather resistance.

Way too many unknowns and possible unintended consequences of course.... this is only just a sidetrack thought to the idea of encapsulated wooded props. I'm not in anyway suggesting it.

Restoration Products Store

Back to the real-world learning here....
can a pilot-owner do the prop refinishing, or does it require an A&P, changing the balance or whatever?

 

[geezer]

Back in the day, a friends uncle had a bakery in a medium size town. It was near the airport, and when the airmail plane came in and unloaded its mail, the pilot removed the wooden prop, carried it to the bakery, which was heated all night, and they placed it in a corner near the ovens. In the morning, the pilot appeared with his lunch and picked up his propeller.

The bakery never charged for this service, which prevented dew soaking in and making the prop unbalanced. They felt that it was their duty to assure the mail did not go down off airport, or get stuck with an unuseable prop.

The postman was not the only person who assisted reliable delivery.

For those who do not have a hanger with a concrete floor, a wooden prop is a dangerous investment.

 

[Dan Thomas]

For the last five years I had the Jodel, I had to store it outside. I made a cover for the wooden prop. I used a light-colored marine-grade vinyl, as it is really resistant to UV, and sewed it up so that one side slid onto the blade, with the seam at the bottom, and then the other side draped over the other blade and a zipper along the bottom closed it up. There was very little exposed prop, mostly a tiny bit at the bottom of the hub. I treated the sewn seams with silicone waterproofing spray.

That prop didn't suffer any damage at all under that cover. It's still in great shape.

Some of you guys need to find an old sewing machine and get to work. Handy when you can do stuff like this.

 

[Dana]

Wooden props are typically smoother running and are definitely much lighter than metal props. They typically have thicker cross sections and are less efficient.

Also, a wood prop is much nicer than metal if you're hand propping.

When I switched from a metal to a wood prop on my Hatz, it was noticeably smoother, I lost about 75fpm of climb (~900fpm to ~825), and it was a 15# weight reduction.

The Sensenich wood prop on my T-Craft wouldn't tolerate any rain, but I was storing the plane outside so UV probably had degraded the varnish and it would chip off the metal leading edge. Or maybe the varnish wasn't as good 40 years ago. Flying through rain in the Hatz, there was no effect on the wood prop, which had a urethane leading edge. It's easy enough to refinish a prop (though perhaps not legal on a standard certificated aircraft?), but it must be balanced.

 

[Pinecone]

Maybe composite props are wood. But with a fiberglas or carbon fiber outer surface. MT and Hoffmann in the certified world

 

[Shepherd]

Personal experience/observation:
As previously stated, a wooden prop is lighter, much lighter.
As a result, there is not as much energy stored in the prop (flywheel effect).
In very cold conditions (below 0 degrees F )I have experienced the engine stopping when throttling back to land.
This was in a Cub with the C-65-8 engine. As soon as it went below 1,900 rpm the engine just stopped, like it was shut off.
With a metal prop the same plane was fine.

 

[Bell206]

and is that something an owner-pilot can do or does it demand A&P's and sign-offs?

Depends. Not all wood props have estblished ICAs, etc as metal props usually do. So you tend to get into the gray area trying to apply prevent mx 43 Appdx A(c)(10) to touching up preventive coatings on props. It can even be a gray area for an A&P on some wood props as it may get into major repair territory with some finish work.

But if you have an ICA that permits touch up of the protective coatings then it could possibly fall under prevent mx and the owner could perform/sign-off the work.

Regardless, wood props definitely have their place with some aircraft but it tends to be very subjective to the person and situation.