Single blade propeller

[Andym]

Hi can anyone shed any light on this propeller.
I think it is an early one but have no info nor can I find any it does look as if it was made as a single ,not been cut and finished but I am finding it difficult to come across another.

[Dbahnson]

Not nearly enough info to even begin to identify it, but had it been constructed as a singe blade it would still need to be balanced by a counterweight (typically wood) on the side opposite the blade.

Here's an example:

[Andym]

Single blade propeller

Hi .thanks for the reply
I have seen many examples with the counterweight on the opposite side but this one appears untouched even on the laminated joints.
I will post some more pics.
Any help is welcome .thanks Andrew.

[Andym]

Single blade propeller

Another pic

[Andym]

Single blade repelled

Another picture

[Dbahnson]

OK, here are my thoughts. Your blade is more likely what is remaining from a 4 blade propeller, likely British, and all of the other blades were damaged. If you look closely at what's remaining you'll see initial stampings which "disappear" into an area that looks striated, as if it's been sanded. Those letters look like typical British nomenclature where "G" refers to "group", "N" refers to "number", "D" refers to "diameter", "P' refers to "pitch", etc., etc.

Those stampings may well have progressed onto the next blade, but were remove by machining and sanding of the other blades, so that all is left of the original blades is the beginning of the identification data on what's left of the hub.



A propeller designed as a single blade without counterweights would be doomed to fail early in its operation. It would shake the engine from its motor mounts in very short time.




















.

[Andym]

Single blade propeller

Hi
Thanks for the reply ,I'm not sure on the theory of a four blade though ?
The main problem is the lamination joints are at 2 o'clock and 10 o'clock if the blade is pointing down ?
If it was a double would they not be at 3 and 9 o'clock ?
Of course you may have it spot on but I am stuck fast and high !
Maybe it was a teaching aid or similar ?
There is too much work in it to be a display I think
One other thing is there are pegs in it to secure the laminate on the blade
Pic included .
I will get a close picture of the hub showing the joints and post them .
Again, all help is gratefully recieved.
Thanks Andrew.

[Bob Gardner]

Andrew,

Dave is quite correct. It is British and from WW1. The G numbers were introduced in September 1917 and continued in use for at least a decade.

The pegs were rather a belt and braces aspect of British design. They must have been intended to hold the laminations together, to prevent creep, perhaps during manufacture. No other country used this device and the British had largely ceased the practice by 1918.

So it is likely that your prop was made after September 1917 and before mid 1918.

After WW1, a large cottage industry sprang up in Britain to convert surplus props into treen, picture frames, hall stands, clock cases and so on. I suspect yours is a rather rare variation on this decorative theme. It does have a certain flair about it.

Please measure it in mm from the centre of the hub to the tip. We can double this to find the diameter which might enable us to identify it.

With kind regards,

Bob

[Andym]

Single blade propeller

Thanks Bob .
I will measure it and photograph the hub with a bit more detail especially where the joints are , I can't imagine it was a four blade as the two blades would be on the joints although I am intrigued by it ,
All help is appreciated but as I said I will photograph the hub in more detail and post the measurements .
Thank you so much for your help.

[Andym]

Single blade propeller

To Bob And Dave.
Today I have had a good look at the prop and upon closer inspection I most definitely think it was a four blade !
The joints are perfectly done and laminated back in with artisan quality engineering.
I will post a few pics of the boss with the joint details where you can see the cuts that have been done .
The measurement is 1400mm from the boss centre to blade tip and it is 210 mm at the widest part .
I hope this may help you to identify it .
Thank you again for all the help and info you have already provided .
I hope to hear the final part of the puzzle soon !
Thanks Andrew.

[Andym]

Single blade propeller

Front pic of boss

[Dbahnson]

Yes, that's one form of 4 blade construction. Notice how the grains run perpendicular at the joint line. In a 2 blade propeller, those would all be parallel.

It looks as if the center hole has been bored out (likely for a clock or barometer) and I think the bolt holes have likely been enlarged as well. The brass plate was probably added to hide the alterations in the hub.

[Bob Gardner]

Good Morning Andy,

I have 2019 British drawing numbers listed and four of them have a diameter of 2800mm. One is for a four-bladed prop, three are for a two bladed prop.

The two bladed ones are;
Drg No AB7953 for a 230hp BHP Siddeley engine in an Avro DH9.
Drg No LP3470A for a 160hp Beardmore engine in an FK8.
Drg No T5638 for a 120hp Beardmore engine in a FE2B

The four bladed one;
AD532 for a 90hp RAF 1A engine in a BE2C

With kind regards,

Bob

[Andym]

Single blade propeller

Hi Bob.
thats the answer I was looking for . It is definitely the four blade one as upon proper inspection it's very apparent where the joints have been re done. I am so grateful for your help and hopefully can repay the favor one day . One last thing ,which aircraft would it be most likely have come from ?
Thanks again
Andrew.

[Bob Gardner]

Andrew,

I'm glad to be able to help but I emphasise that this answer above is only a probability.

To expand the data into English;

AD532 is the drawing number where AD indicated the Air Department of the Admiralty, meaning the prop was made for the Royal Naval Air Service.

90hp RAF 1A engine indicates the improved version of the 90hp engine designed by the Royal Aircraft Factory.

BE2C indicates the aircraft, also designed by the Royal Aircraft Factory. It was designed to be a stable reconnaissance aircraft from which the Observer could take sharp in-focus photographs of the German positions on the Western Front.

This inherent stability meant that it could not out manoeuvre enemy fighter aircraft which first appeared in mid 1915. It continued to be used in the recce role but protected by British fighters until 1917. Thereafter it was used in training and as a squadron hack.

With kind regards,

Bob