DBC, Davenport Brown propeller, 100" / OX 5 , 8 bolt

[Dennis]

I have a Davenport Brown propeller that is made in Somerville, Mass. and it says "First at the Finish". Is this a racing propeller or just a slogan? I can't find anything on this brand and would like to know a little history if someone has knowledge about it.
The propeller fits all of the hub dimensions of the Curtiss OX5 engine.
S.C. No. 61145 ( Signal Corps? )
100" long
1400 RPM
A.S. 70 MPH
Hub thickness, 4 inches
Hub Diameter, 6 inches
Center bore, 2.69 inches (measured right under 2 3/4 inches )
Bolt Circle C/C is 5.25 inches
8 bolt holes
Pitch is 5 foot. 3 inch
On the back of the hub is the number 92 stamped into the wood.

The propeller looks like it has it's original coating or recoated many years ago and the original decal. There are two areas that have repairs but they look like that happened at the time of it being used.

[Dennis]

A little history about the former owner of this propeller. I've had it for 25 years and the former owner was in the Navy on the U.S.S. Blue and ended up in Hawaii in around 1940. He was a navy cook and was stationed in Hawaii during the war. I have several menus from Thanksgiving and Christmas Dinners that were put on during that time. But not sure where this came from or how long he had it.

[Dbahnson]

The geometric design is a "toothpick" propeller, which was commonly used on the JN4 "Jenny" biplane, although possibly used on other aircraft as well. The design was a product of a simple goal of using less lumber than the scimitar shaped props that were common in the 20s and 30s.

Although I've never heard of that manufacturer, there were literally hundreds of manufacturers competing for contracts with the Navy and the Signal Corps for the manufacturing of propellers in the late teens. Piano manufacturers and others had the equipment and the procurement avenues for lumber that gave them a head start in their bidding process.

See this link for a similar (or identical) designed prop. I've seen a number of them from a variety of manufacturers. See also this link. A little further Googling the name indicates that the company was in existence in the early teens.

As you may have read in one of the sticky threads here, it's important that your prop be left in its present condition. It has obvious signs of actual use and retains an original decal, so any attempts to "restore" it just lowers its value as a collectible.

[Dennis]

Thanks for your response, interesting that they made propellers lighter and cheaper for this application on trainers and got the nickname "toothpicks". I tried to find the manufacturer in a search but with no luck, with the war effort and the need for many propellers I see where a lot of companies that worked with wood had the opportunity to manufacture propellers.
I have a question about rotation. Are all or most aircraft engines right hand rotation? Is this from the pilots seat to determine left and right hand sides of the plane. Then most propellers are right hand and if the engine was in the rear it would be a pusher and use a left handed propeller?

[Dbahnson]

Most of the common aircraft engines in WW1 were right hand rotation, that is they attached to a propeller with a right hand thread, like a screw, that when turned clockwise from behind, like a screw, would move forward. Some engines like Renault were left hand rotation, and some engines like one of the SPADS were geared, which reversed the rotation.

But yes, in general a right hand rotating prop was typically a tractor application and a left hand one was a pusher configuration, but there were a number of exceptions. You can't determine pusher or tractor application simply by the thread rotation, for reasons noted above, so any propeller could be a pusher or tractor depending on the engine and/or its location on the front or the rear of the aircraft. Aerodynamically they are the same.

Some further discussion here.

[Bob Gardner]

I've read these emails and Dave's further discussion. I thought I should add that during WW1, whilst the British and French and probably all their allies described the direction of rotation from the point of view of the pilot, the German Flying Troops described the rotation as seen by someone standing in front of the aircraft.

Also some German propellers were used in both right hand and left hand rotation which led to colour-coding on the hub. Thus Eduldruck and Mulzug propellers were identical to Muldruck and Edulzug propellers, so Idflieg in the document Idflieg Flugzeugmeisterie Abt BB, Nr 478976 introduced colour-coding on the hub.

Similarly the British colour-coded their props so LHR props had blue bands at the blade roots and RHR props, red.

With kind regards,

Bob