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Larryh86GT
10-03-2015, 12:46 PM
I recently purchased this old Sensenich Bros propeller. While I know I will probably never know it's story it looks great with nice patina. It was owned by a 92 year old pilot who was a barnstormer in his younger days and had survived 9 crashes over time. I am thinking if he saved it it must have held a good story for him. I cannot find much information on the propeller. It is stamped with:
D.102.
No.850.
A.T.C.450.
and also stamped with the number 850 and the number 1
There is still some cloth left on one blade.
I assume the D102 means it was 102" long. Right now it measures 80" from one broken end to the other.
The hub is 4" thick.
The center hole diameter is 2 3/4"
The bolt hole circle is 5 1/2"
The bolt hole diameters are 3/8"
It's going to look great mounted on my wall.

Larryh86GT
10-03-2015, 12:48 PM
Some more photos:

Dbahnson
10-04-2015, 09:14 AM
The "ATC" refers to the Type Certificate, but I can't find that listed for any Sensenich propeller, or for any other manufacturer for that matter. Looking closely at the photo it looks as if the "5" may actually be a "6". (You might check it with a magnifying glass or other enlarging technique.) The only Type Certificate number of 460 that I can find was listed for Hartzell. (See attached scans.) Note that the hub thickness, bolt hole diameter and bolt circle diameter are all consistent with the numbers on your list, and correspond to Hartzell model number 706 (E,EI, and I) which had a diameter of 83" or 82" and was designed for use with a 145 HP engine.

If you look up Hartzell number 706 on this page (http://www.woodenpropeller.com/MWPHartzell.html) you'll see the propeller listed for various Fairchild aircraft with the Warner 145 HP engine.

Sometimes one manufacturer (in this case Sensenich) would manufacture props using the Type Certificate from another (in this case Hartzell) under agreement. I think the scimitar shape of yours is also consistent with a Hartzell design, so it all fits.

It's VERY likely that your measurement of 80" is consistent with an original size of 83". It just doesn't look as if 22 inches of prop are missing on that photo.

So all in all I'm 95% certain that prop was designed for a Fairchild airplane with the 145 Warner Scarab engine and was manufactured by Sensenich under Hartzell's type certificate. The type certificate expired in 1954, but I suspect you prop was manufactured in the 30s or 40s.

Larryh86GT
10-06-2015, 09:39 AM
Thanks for the quick reply and information. The ATC number is definitely 850. I have posted a clearer picture.

A couple of questions:

1. Normally isn't a "D" on a propeller indicative of it's length?

2. One of the blades is 42 1/2" long to center with 24" of brass. The other blade is 37 1/2" long with 18 1/2" of brass. There is 6" of cloth showing on the longer blade and no cloth showing on the shorter blade. Normally wasn't
the tip enclosed in brass also on these types of propellers? So the propeller
was at least 86" long and probably longer with the amount of damage
showing.

3. According to the characteristics of an "Earlier Wooden Propeller" on this site they are generally 8 bolt holes, darker woods, often scimitar, and fabric covered tips.

4. From the looks of the age of this propeller might it be a propeller made by Sensenich before they kept records?

Just curious.
Thanks,
Larry

Larryh86GT
10-06-2015, 07:42 PM
A better photo of the propeller:

Dbahnson
10-06-2015, 10:35 PM
Thanks for the quick reply and information. The ATC number is definitely 850. I have posted a clearer picture.

A couple of questions:

1. Normally isn't a "D" on a propeller indicative of it's length?

In British props that is common, but not so much on U.S. propellers.

2. One of the blades is 42 1/2" long to center with 24" of brass. The other blade is 37 1/2" long with 18 1/2" of brass. There is 6" of cloth showing on the longer blade and no cloth showing on the shorter blade. Normally wasn't
the tip enclosed in brass also on these types of propellers? So the propeller
was at least 86" long and probably longer with the amount of damage
showing.

Usually there was curvature around the tip, so I agree that it was likely longer than 86", but I'm still skeptical that it was 102"

3. According to the characteristics of an "Earlier Wooden Propeller" on this site they are generally 8 bolt holes, darker woods, often scimitar, and fabric covered tips.

That's only a very general guideline, probably more applicable in reverse, i.e. most early propellers had 8 bolt holes. Modern propellers are usually 6 bolt holes but 8 holes are still very common.

4. From the looks of the age of this propeller might it be a propeller made by Sensenich before they kept records?

But the reason they start the listing as 1932 is that's the year the business started.

Just curious.
Thanks,
Larry

I think the next step in your quest is to see if you can find a record of the Type Certificate #450. It will likely take some some footwork.

Larryh86GT
10-06-2015, 11:05 PM
Would this match up?

ATC450 American Eagle B-31

Dbahnson
10-07-2015, 12:26 PM
I don't think so. I think that Type Certificate is for the Eaglet airplane, not the propeller, and as near as I can tell that airplane used a 45 to 50 HP engine, which would not likely be using a prop of that length, although I suppose it's possible.

Larryh86GT
10-07-2015, 12:49 PM
Thanks for trying to identify it. I guess it is a mystery propeller. It is still very cool looking and I will be mounting it on the wall shortly. Here is a better picture of one blade of the propeller. I finally figured out how to attach better pictures.
Larry

Dbahnson
10-07-2015, 01:19 PM
Maybe try contacting Sensenich and ask them about TC450. They list a number of props with TC numbers in the 400s, including 449 and 452, so it may just be that it's not included in the listing I have, which is from a 1983 FAA publication.

Larryh86GT
10-07-2015, 05:32 PM
I have sent them an email about it. Hopefully they may help. Or possibly someone else may have one of these and can jump in.
Larry

Dbahnson
10-07-2015, 09:33 PM
Propellers were like tires. Lots of them fit lots of airplanes and the markings don't tell you which airplane, anymore than tire numbers tell you which car they were used on.

Larryh86GT
10-27-2015, 03:06 PM
I received a reply from Sensenich on the propeller. It was a 102" propeller used with the OX5 engine (whatever that was?) Pretty cool though:

"Hello Larry,
This propeller is used on various aircraft with the OX5 engine. Your propeller was probably manufactured between 1932 and 1942. The current retail price for his model new is $3,980.00. The propeller was originally 102Ē inches long. The current model number is W102 and a new propeller would have the same shape as yours. Sorry but we have not made one of these in years and I donít have a photo."

Dbahnson
10-27-2015, 10:37 PM
The OX5 was a notoriously unreliable water cooled V8 engine that was used on many different airplanes through the late 1930s. I remember it once being referred to a a "bunch of moving parts flying in formation". See this link (http://generalaviationnews.com/2011/01/10/the-ox-5-era/) for a few of the aircraft that it was fitted to. Keep in mind that even though some aircraft were built in a specific year, the need for parts often lasted well beyond the year of manufacture, which is probably why Sensenich might even offer a replacement model many, many years later.

Larryh86GT
10-29-2015, 10:19 AM
That is an interesting article on the OX5 engine. Thanks.