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Spacc29
05-02-2012, 01:06 AM
Hi,

I have a Vintage wooden Propeller that was passed down to me, and I would just like to see if you guys can help me out with its history and possible value.
The maker is: Munk Aeronautical Laboratory Inc Brentwood, Maryland. It says FloxOProp.
The numbers on the middle of the prop are:
Top corner says 1 Patent 2484308
other side says 2 TC872
SER 214
74 L 63
Its about 6' in length, any information would be greatly appreciated! Thanks!

Dave
05-02-2012, 11:09 AM
I'll have to look through a few files when I get home.

"TC" is the Type Certificate number

74 L 63 likely means a diameter of 74" and a pitch of 63", the "L" may refer to a Lycoming engine and hub.

"Ser 213" is likely the serial number, which is a low number and probably indicates a small production factory.

Spacc29
05-03-2012, 01:21 AM
Hi Dave,

Thank you so much for your help. Any info would be greatly appreciated. What era do you believe this is from? From what I gather the Maker Max Munk Has done quite a bit in the aviation industry such as inventing the wind tunnel.
Thanks again and I look forward to your reply, John

Boiler aero guy
07-14-2012, 04:12 PM
Max Munk was a very famous aero pioneer. Munk's “Flex-o-prop” design was patented in 1949 (Propeller Containing Diagonally Disposed Fibrous Material). His fibrous material was laminated wood. In his patent application Munk noted, “It is the purpose of the present invention to provide a pitch propeller the blades of which twist elastically and favorably as the thrust changes. This is accomplished by at least a portion of the blade of fibrous material, preferably wood, so disposed that the fibers are disposed diagonally, not radially… relatively small favorable elastic twist angles noticeably improve propeller performance … the reality of the twisting effect is beyond doubt.” There is a later patent but the number you cite is the first patent.

I think you have a real historical item; he could not have made too many of these.

Dave
07-14-2012, 04:31 PM
Interesting patent. I've got some Spencer Heath (Paragon) documents from the late teens or early twenties that discuss the variable pitch/thrust relationships with respect to thrust, but I'm not aware that they ever applied for a patent for it, although they did advertise that their more scimitar shaped props would provide that feature.