P47C/D Prop blade Serial No question...Date question...and Yellow tip question for restoration..

littorio · Feb 3, 2021

I just picked up , what I believe to be a Curtiss C2721200 "toothpick" style prop blade. Finding the War time Curtiss logo was easy so that's done. I will be restoring this blade to its original condition but need help determining what info I will use for the cuff stencil (in yellow). Research has determined that the info should read as follows:
DWG.NO.C2721200
SER.NO.??????????
ANGLE LOW 27.3
ANGLE HIGH 57.3

question 1...what was the Serial number?? Is it a specific one of a kind fingerprint number assigned by the Curtiss factory? Was it a corresponding number related to the tail number of the aircraft it was mounted to the specific aircraft? What should the SER. NO. be for my blade?

question 2, should I make up a random date for the fifth line (ex: 1-7-43) or just leave it out all together?

question 3, the yellow tip.....painted on the front only or both sides? It my understanding the yellow tip would distract the pilot so its on the front alone?

Thanks in advance!!

mjfur · Feb 4, 2021

The s/n of the blade was assigned/created by Curtis and has nothing to do with the aircraft s/n.
Yellow tips were on both sides of the blade. https://www.b-29s-over-korea.com/NASA-Photos_I/images/P-47C-Thunderbolt-NASA.jpg
I would presume the date is date of manufacture.

Michael Hope · Feb 4, 2021

The date could also be the overhaul/major repair date for the blade, not the manufacture date.

Tom Fey · Feb 4, 2021

The serial number of the blade should be "electric penciled" into the curved bottom of the segment gear insert that is screwed and pinned into the bottom of the blade. The segment gear blade plug was matched to the blade at time of manufacture and thus both blade and plug must have the same serial number. A scotchbrite pad with some motor oil will likely reveal the numbers.

Tom Fey · Feb 4, 2021

As for the tips, looks like it is your choice. Period photographs show CE blades with and without yellow tips on the thrust face.

littorio · Feb 4, 2021

Tom Fey said:
The serial number of the blade should be "electric penciled" into the curved bottom of the segment gear insert that is screwed and pinned into the bottom of the blade. The segment gear plug was matched to the blade at time of manufacture and thus both blade and plug must have the same serial number. A scotchbrite pad with some motor oil will likely reveal the numbers.

What part is the Curved segment gear? My prop has a cuff on it but the screws seem to be seized in place so I most likely won't be able to remove it.....I'm guessing the info I need is of course right under that cuff cover ?

littorio · Feb 4, 2021

Tom Fey said:
As for the tips, looks like it is your choice. Period photographs show CE blades with and without yellow tips on the thrust face.

Thanks for those pics!! I think I read at some point that pilots were annoyed by it during flight...looks like early types and back home models had it...combat arena it was removed

Tom Fey · Feb 4, 2021

littorio said:
What part is the Curved segment gear? My prop has a cuff on it but the screws seem to be seized in place so I most likely won't be able to remove it.....I'm guessing the info I need is of course right under that cuff cover ?

The serial numbers will not be found under the cuff. Look at the page from the Curtiss brochure attached here. The blade gear has an arc of gear teeth on it and is the lowest assembly on the blade, just below the three bearings. When you stand the blade upright, the blade gear is what is touching the floor. The center of the blade gear is concave, and somewhere on that concave surface you will find the serial number. The serial number can be seen in the attached photograph in the polished section of the blade gear. The blade drawing number will be found on the bottom of the blade itself, in the gap where the blade gear meets the blade itself, but visualizing this might require removing the blade gear and bearing stack.

littorio · Feb 5, 2021

Tom Fey said:
The serial numbers will not be found under the cuff. Look at the page from the Curtiss brochure attached here. The blade gear has an arc of gear teeth on it and is the lowest assembly on the blade, just below the three bearings. When you stand the blade upright, the blade gear is what is touching the floor. The center of the blade gear is concave, and somewhere on that concave surface you will find the serial number. The serial number can be seen in the attached photograph in the polished section of the blade gear. The blade drawing number will be found on the bottom of the blade itself, in the gap where the blade gear meets the blade itself, but visualizing this might require removing the blade gear and bearing stack.

Ahhhhhh. You know when I bought this prop that is the first place I looked for some kind of identification number and could not find it. I'm going to take a closer look later tonight, I'll post a picture of what I find. I don't remember seeing anything at all stamped there the first time around. I think I may have to perform surgery and remove those pieces, I'm not sure how to move forward with that because everything is so seized. We will see , fingers crossed

Tom Fey · Feb 5, 2021

littorio said:
Ahhhhhh. You know when I bought this prop that is the first place I looked for some kind of identification number and could not find it. I'm going to take a closer look later tonight, I'll post a picture of what I find. I don't remember seeing anything at all stamped there the first time around. I think I may have to perform surgery and remove those pieces, I'm not sure how to move forward with that because everything is so seized. We will see , fingers crossed

Use a scotchbrite nylon scrubbing pad, motor oil, and elbow grease. Good hunting!

littorio · Feb 5, 2021

Tom Fey said:
The serial number of the blade should be "electric penciled" into the curved bottom of the segment gear insert that is screwed and pinned into the bottom of the blade. The segment gear blade plug was matched to the blade at time of manufacture and thus both blade and plug must have the same serial number. A scotchbrite pad with some motor oil will likely reveal the numbers.

So here's what I found. After an oil cleaning there are no numbers in the steel so far. On the aluminum I found something but it's in bad shape. I used a black marker to help the characters pop visually. Here's some pics. Do you think I will need to remove the segment to find the numbers?

Tom Fey · Feb 5, 2021

I believe I see characters in the circled areas on the blade gear. Also attached please find a photograph where the blade drawing number will be found on the butt of the blade. Removing the blade gear will be a challenge. This would require the removal of the cuff, slide the nut and bearing stack up so the pin can be removed, then the blade gear unscrewed from the the blade. I suspect they are corroded together forever. I will tell you I have never done any of myself, but have read some of the manuals. The numbers on the dark gray cuff bracket are likely not the serial or drawing numbers for the blade, but are rather the part or serial numbers for the bracket itself.

littorio · Feb 5, 2021

Tom Fey said:
I believe I see characters in the circled areas on the blade gear. Also attached please find a photograph where the blade drawing number will be found on the butt of the blade. Removing the blade gear will be a challenge. The pin needs to be removed, then the blade gear unscrewed from the the blade. I suspect they are corroded together forever. The numbers on the dark gray cuff bracket are likely not the serial or drawing numbers for the blade, but are rather the part or serial numbers for the bracket itself.

I agree, I don't think I can remove gear..its pretty old. I'll investigate the areas highlighted more closely this weekend and follow up with results...thank you so much for helping!!

Tom Fey · Feb 5, 2021

littorio said:
I agree, I don't think I can remove gear..its pretty old. I'll investigate the areas highlighted more closely this weekend and follow up with results...thank you so much for helping!!

Please note I made few edits and additions to the previous post.

littorio · Feb 18, 2021

Tom Fey said:
The serial number of the blade should be "electric penciled" into the curved bottom of the segment gear insert that is screwed and pinned into the bottom of the blade. The segment gear blade plug was matched to the blade at time of manufacture and thus both blade and plug must have the same serial number. A scotchbrite pad with some motor oil will likely reveal the numbers.

Upon investigation I've found this!!
Is this the serial No. I've been looking for?? If so, going to be a challenge trying to read it...any suggestions??

mjfur · Feb 19, 2021

That's it. Use a magnifying glass or jewelers loop. You can smear some "White Out" or something similar on it, then wipe off the excess, it will fill in the numbers.

Michael Hope · Feb 19, 2021

When I am trying to see faded numbers I use a fluorescent light, not LED lights, and then using the magnifier. Smearing with a dark substance and then clean the top surface should leave behind a better view.

littorio · Feb 19, 2021

Michael Hope said:
When I am trying to see faded numbers I use a fluorescent light, not LED lights, and then using the magnifier. Smearing with a dark substance and then clean the top surface should leave behind a better view.

Great info!!! Will get a fluorescent light!! Tx!!!!

littorio · Feb 19, 2021

mjfur said:
That's it. Use a magnifying glass or jewelers loop. You can smear some "White Out" or something similar on it, then wipe off the excess, it will fill in the numbers.

Going to try the whiteout approach, hope the grooves are deep enough to capture some of the filling in. This is exciting, once I have the number, I can fully restore this old toothpick prop !!!! Thank you so much for the guidance!!!!!!!!

Tom Fey · Feb 25, 2021

littorio said:
Upon investigation I've found this!!
Is this the serial No. I've been looking for?? If so, going to be a challenge trying to read it...any suggestions??

Nice work! If your blade is a P-47 toothpick, the blades will be a 714-1C2 or a C2721200 series. I have photographs of a C2721200 series blade, and the serial number on that blade was "SER NO 44-23175" and underneath that is was stamped "RHTHREAD". The yellow stenciling on the camber face of the blade confirmed the serial number. You might try rubbing some slightly diluted black enamel around the area with a gloved fingertip. Can always be removed with thinner. I'd also suggest you take some high quality close photographs of the area with a tripod outside on a bright but cloudy day. Throw those images in some of the photo editing programs, play around, see what you can reveal. Good luck.

P47C/D Prop blade Serial No question...Date question...and Yellow tip question for restoration..

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