US Propeller Inc. Please help!

[wadejc85]

Hi everybody, I need your help! My grandfather has given me a propeller, and I am trying to track down what plane it is from. He said that his father bought a number of war bonds to receive the propeller.

It has this stamped into the sides:

(first side)
US Propellers Inc.
CONTW535AC35196
Plane 16

(second side)
DES 76FGS64
SERAF 4310468
RPM 2200
HP 115
TC 787
ENG FRANKLIN

The length is 72 inches and it has 5 "holes" (sorry, I don't know the correct terminology). Here is a picture of the propeller:





Please, any information would be very much appreciated! Thanks!

Wade

[MWP_Lamar]

This is a tough one to identify. First, US Propellers primarily made props for target drones (unmanned small aircraft used for target practice). They did make conventional aircraft propellers but to my knowledge details of their design or drawing numbers haven't survived. I attempted to id it by the engine but I failed to find any Franklin aircraft engine rated at 115 horsepower.

I realize there are 5 holes in the display plate, but are there any bolt holes that go entirely through the prop's hub? Most likely 6 bolt holes arranged in a circle plus a larger center bore. A look at the back side of the prop should reveal them.

If this prop was given as a premium for purchasing war bonds it may have failed quality control, therefore suitable for display only and never drilled.

Lamar

[Dave]

That specific design number, 76FGS (64 is the pitch), did have a series that was rejected, specifically serial numbers 10000 through 10731, which would include yours if the "43" represents the year of manufacture (which it may, if "AF" implies a military contract). Those props had a 3 1/4" bore and eight 7/16" diameter bolt holes on a 5 1/4" diameter bolt circle.

You should probably remove the plate and check underneath.

[wadejc85]

Propeller info

Lamar and Dave, thanks for the information!

I removed the back plate and there are eight half inch holes, and the center hole is 3 and 1/4 inch. The eight holes are plugged with cork and there is a number stamped into it. The number is 10468. I'm guessing this is the serial number, and since it is in the range, it was rejected.

Do you happen to know specifically what these propellers were used for? What type of target drones? If not, thanks for the info anyway.

Thanks!!

Wade

[Dave]

Although U.S. Propellers made mostly drone propellers, yours was one of the models used on aircraft, but I don't know which specific one it was for, although the 115 hp Franklin engine does narrow it down somewhat.

[MWP_Lamar]

I tried to ID this prop by the engine but was unsuccessful. Even the widely recognized authority Jack Erickson’s extensive listing Development of Horizontally Opposed Aircraft Engines doesn’t list any Franklin engine from any time period rated at 115 horsespower. Perhaps it was rejected because it was mis-labeled?

[wadejc85]

Franklin engine

Dave and Lamar,

I found this website that lists a few Franklin engines from the time and at least two of them say that they could run at 115 hp. Here is the link: http://www.aerofiles.com/motors.html. The Franklin engines are about halfway down the page. Do you think this information could identify the engine?

Also, I really want to thank you two for the time you are putting into helping me identify this propeller. I really appreciate it!

Wade

[MWP_Lamar]

I’m not sure what you mean when you say Aerofiles lists Franklin engines that could (emphasis mine) run at 115 hp.

There is one possibility listed in your Aerofiles reference in brown colored type but it’s an undocumented member of the O-200 family of engines. It appears to be type certificated but its use, assuming it had one, seems to be undocumented or unknown.

If you mean a reference to a family of engines listed as 75-150 hp for example, that just means that family has engines in that horsepower range.

Perhaps you meant something else?

You’re certainly welcome for any help I may be able to offer. It’s my pleasure. I enjoy doing this sort of thing. It’s still amazing what I can learn by trying to seek information for another.

Lamar

[wadejc85]

I was not certain about any of the information I found on Aerofiles. I simply Googled some of the numbers and clicked on different links I found on Google. I was just guessing blindly, which I shouldn't have done.

I'm sorry I haven't posted in the past couple days. I have had computer problems that have left me computerless.

Again, thanks for the information. I appreciate it so much!

Wade

[MWP_Lamar]

The prop definitely is either mis-marked or was indeed for 115hp Franklin. Perhaps it was an engine that was planned but never put into production? There are several possibilities. We may never know. What an intriguing mystery!

[bcbcbc]

ID

I wish all these people would stop filling space on the forum when they have no useful information. The prop you mention is for a 1943 Interstate L-6. I would be happy to purchase it from you if you would like to sell. Thanks.