Need help with my Lang Prop

[gramfly]

HI everyone, I have a Lang prop circa 1918 or so. It is 94 and 3/4 inches long, hub diameter is 7.5 inches, center bore measures 2.75, and the hub thickness is 4 7/8 inches. The number by the hub plate on the front is stamped 58259 and is preceded by the letters SO which are not stamped but appear to be maybe burned in. Also there is the number A7 above the SO # with a mark like an upward pointed arrow (See Pictures).
After reviewing your chart of hub dimensions the best matches seem to be the 110 hp or the 130 hp Clerget engine, or possibly the Gnome 100 or 160.
Family lore has that my great uncle Newton flew in WWI and returned from France with it.
I have attached pictures, (I hope), I am new to this type of thing. I am interested in any help I can get as to the possible aircraft it was used on and value. Thanks in advance.

[Dave]

Could the "SO" actually be "SC"? It may be a Signal Corps number.

You need to measure the bolt hole circle. See this link.

It's possible that it went to France and then came back again, but it's more likely that it was manufactured here in the U.S. and sold as surplus in the early to mid twenties. There's no way to be sure. The only U.S. built airplane to see combat was the DH4, but this doesn't look like a fit for that.

[gramfly]

Hi dave, thanks for getting to me. I just measured the bolt circle at 5 and 7/8 inches.

[Bob Gardner]

Your prop dates from Summer to Autumn of 1917. By late 1917 a different decal was used by Lang. The diameter suggests a Hispano-Suiza 180hp engine which was used on the early SPAD scouts used by the USAS in France.

With kind regards,

Bob

[gramfly]

Need help with my Lang Prop

Hi Bob, That is interesting. The story from my Mother about our Uncle Newton always was that he brought it back with him from France. Not much info was passed down to us kids as "poor old" Uncle Newton died in the late 1920's in a flagrant suicide at his brothers ranch north of San Francisco during a big pool party. He reportedly jumped 30 to 40 feet out of a tree onto the patio in front of everyone. NO one knows the reason but there apparently were rumors about his "masculinity". Anyways, I have found two old pictures of him taken in France. One is, I was always told by my Mother, his niece, of him sitting on the very prop I have. It does look to me a lot like it and I have included the pic's here to take a look at. See what you think. One of the planes is a two-seater and I am not sure about the other.
Thank You, Greg

[Dave]

Well, that certainly doesn't look like a SPAD, which had I think had a fairly characteristic cowling with exhaust stacks trailing back from the top of the cowling. It may very well be a rotary engine, however, and it sounds like a Clerget or Gnome is a good possibility.

The real airplane history nuts can usually identify the plane from features of the cowling, struts, etc. that are visible in that photograph. I would consider registering and posting on www.theaerodrome.com where some of the members love this kind of mystery plane identification.

[gramfly]

Thanks Dave, I should of done this years ago. I have always been interested but until computers came along, and I learned how to use them, I had no way of finding out much. Kudo's to you for this site. My current situation now dictates that if there is any real value to it I will have to sell it. I will check out the aerodrome.com. Thanks for all your help.
Greg

[Bob Gardner]

Greg,

The second aircraft is a Sopwith Pup I think. I can't tell what the two-seater is. I didn't know the USAS used the Pup. They did buy 514 of the Pups' predecessor, the Sopwith One-and-a-half Strutter. Both used French rotary engines but the props for these were much bigger than 2400mm, or at least it was so with the French and English aircraft and props.

I should add that the prop in the second photo is definitely an American Lang prop, not an English Lang Prop. The majority of Lang props were of this shape so it might be that your Great-Uncle got hold of an unservicable prop from some other aircraft, and that his is not necessarily the prop in photo 2.

Bob

[Bob Gardner]

Greg,

I am smitten by uncertainty. I now think that the second aircraft is not a Sopwith Pup but an Avro 504. I look forward to hearing what the Aerodrome experts deduce that both are.

Bob