Which airplane?

[Olaf Oomes]

Dear All,

I recently bought a early wooden propeller made by the firm Hembrug (a firm in Holland), apparently Royal given the crown above the letter W for queen Wilhelmina. The year given is 1918 (see attachment for recontruction of emblem on the propeller).
Furthermore the following information is available on the propeller:
- MODEL HM
- SPOED 170
- 230 PK BEN7
- D 296

Also printed in are:
-N 5 and on the tips on one side 1 and on the other side 2

Could somebody explain to me what BEN7 and N 5 means as well as the function of the 1 and 2 near the tips of the prop?

Furthermore I would be highly interested to know on which aircraft this propeller most likely would have been part of.

[Dave]

Usually the "1, 2" numbers on each blade are just for reference, presumably for balancing and possible for timing the engine once it's mounted.

Could the Ben7 actually be "BENZ", and 230 represent the horsepower?

I'd be interested to see a picture of it.

[Olaf Oomes]

Thanks Dave for quick response. Indeed BEN7 might very well be BENZ. If so does might this mean that the propeller was made by BENZ factories in Germany?
I tried to upload fictures but was unable to do so. Probably the files were to large for the forum to except. I will give it another try later in time.

Olaf

[Dave]

Yeah, we're on a limited budget here so the files have to be a little smaller to upload than on some sites. If you're having trouble, see this link.

[Olaf Oomes]

Thanks again Dave. I will have a look at it.

Olaf

[Bob Gardner]

Hello Olaf,

Welcome.

Your prop appears to be Dutch with a diameter of 2.96m and a pitch of 1.70m which would indicate a slow and probably heavy aircraft. The Benz 230hp engine was used on a number of German aircraft in 1917 and 1918; AGO C II, DFW C V, Rumpler C III, Gotha G II, and SSW R IV.

The pitch suggests it is from the last two bomber aircraft (Gotha and SSW) rather than the C type aircraft which were armed recce aircraft.

With kind regards,

Bob

[Bob Gardner]

Postscript.

I forgot to mention that the metal sheathing suggests either a pusher aircraft or a seaplane.

Bob

[Olaf Oomes]

Thank you very much for this information Bob. Extremely interesting and helpful. I will search the internet for pictures of the aircraft you mentioned. Just one additional question though. Why is it that the copper sheathing at the tips of the prop suggests it belonged to either a pusher aircraft or a seaplane.

Olaf

[Bob Gardner]

Olaf,

In both cases props in these circumstances were subject to erosion or damage. In the case of the pusher aircraft, dust, grass, twigs and sometimes stones would be thrown up by the undercarriage. On a seaplane water would be thrown up and the blade tip would receive most damage because it was moving faster than any other part of the prop; close to supersonic by the end of WW1.

With kind regards,

Bob

[Olaf Oomes]

Thanks again Bob. Makes sense.

Olaf