Pitch of Sensenich 86B1

[earlybird]

We have a Sensenich 86B1 wooden propeller on a 1939 Fairchild 24R9.
86 obviously refers to the prop's length but what pitch does this propeller have? Can't find it in any list.

[Dave]

Don't know. Usually it follows the length, then letters designating the hub.

[earlybird]

Thanks for replying, Dave. The correct prop for the aircraft, according to the list on www.modernwoodenpropellers.com/sensenich.htm would be 86BAS55 or 86BS55. Alternatively a 58" pitch cruise prop may be installed. BAS/BS refers to the engine the prop was designed for (Ranger 6-410)
Our propeller has a serial number without a letter prefix which puts its production date between 1932 and 1942.
Still, I'm at a loss what the B1 designation means.

[MWP_Lamar]

According to an undated Sensenich document I have, the letters following the diameter and preceding the pitch indicate the basic blade design and describe the hub dimensions for a particular metal hub to fit the prop.

Lamar

[earlybird]

Do you think that the pitch information is missing? (It can't be 1 inch The propeller is mounted on a metal hub which fits on the tapered crankshaft. It works OK but the plane is very reluctant to climb.

Frits.

[MWP_Lamar]

The 1 is part of the hub info.

Yes, I think pitch is missing but intentionally. I notice particularly in the older props if it was made in only one pitch the pitch is not stamped. How old is your plane and what is it?

Lamar

[earlybird]

The plane is a 1939 Fairchild 24R9 with a 165 hp Ranger 6-410-B2a engine. The TCDS gives no particular data for the propeller except that it should be a wooden prop not longer than 103 inches tip to tip. No info on pitch or min/max static RPM.

Frits.

[MWP_Lamar]

I bet I've seen pictures of your plane. Nice!

Have you checked with a prop shop or perhaps Sensenich customer service for recommendations?

Lamar

[earlybird]

I have sent an e-mail to Sensenich but received no reply so far. Apparently it is a difficult matter for them too
Also I have posted a question on the Fairchild Club Yahoo Group to find out what the standard pitch for this aircraft is (55 or 58 inches). Just have to wait for a reaction.
And I have tried to measure the pitch of this prop; after some calculation came up with ca. 60 inches, which is very coarse for this type of plane/engine.