T.6296 hub and replica propeller

[Garuda]

As discussed in another thread I have been researching the T.6296 four bladed propeller. It was primarily used on the RE8, but I recently discovered that it was also used on the BE12. I measured a T.6296 blade which had been broken off in a nose over crash. It is almost certainly from an Australian Flying Corps RE8.

I was recently granted access to a complete T.6296 via a very helpful contact I have known for more than 30 years. He worked at the Australian War Memorial. I worked there too, firstly as a volunteer aircraft restorer, and more recently as a contractor, restoring vehicles. I have not been able to see this propeller yet but in the meantime I have been able to work a deal out with another collector. He has very generously agreed to send an original T.6296 hub over for me to measure.

I have been working on drawing the T.6296 as accurately as possible, with the information I currently have. I will check my drawing using the hub, when it arrives to ensure accuracy, and correct my drawing as required. When I have completed my patterns, I will check them using the complete T.6296 as a source of reference.

[Garuda]

T.6296 boss patterns

I used an augmented reality app to project an image of the boss onto 3/4” Radiata Pine. I traced the outline, and cut the pine with a 5mm or so extra margin. The reason for this is that it’s a lot easier to remove pine than it is to add it. Further, there is evidence that the timber has shrunk over the last century. I should, perhaps have left a larger margin. Still, I am very happy with the shapes and dimensions of the boss so far. The blades are located further back than I had estimated them to have been. I do not currently have the original boss photographed to take measurements from, but I am happy that scaling from the photographs has provided a reasonably accurate outline, to within a few mm. I can always alter the patterns, and / or construct new patterns if and when more accurate information is available.

[Dbahnson]

I'm not quite sure what it is that you are trying to accomplish. Please explain a little further.

[Garuda]

T.6296 patterns

I am only in the early stages of developing the shapes and dimensions for the T.6296. It is a four bladed propeller, which was used on the RE8 and the BE12. I measured an original T.6296 blade in 2011. The equipment I had at the time was basic, but reasonably effective. I also have an original T.6296 propeller blade tip for reference. About a month ago, I was able to find an original T.6296 boss. The owner of this boss very generously offered to send it over to me so I can take some key measurements from it. The blade I measured was broken off at the half laps. You can see them in the photos of the Radiata Pine patterns I posted the photos of. I am currently sanding the half laps so that they fit together. When I have done this I will post a photo of the two blades put together at 90 degrees to each other. The reason I have cut the blades at various distances from the centre is that I do not have a drawing for the T.6296. The partial blades you can see in my photo are for the purpose of shaping the propeller blade sections at various distances from the centre line. Generally speaking, I will determine the propeller blade sections where the laminations are pegged together with dowels, approximately every 8". Apart from the relics already mentioned I have access to other relics such as another blade and a complete T.6296. The first step is to make the drawings, so that I can ensure the blades are constructed accurately. I will also post a photo of my drawing as it has progressed so far. It is a bit difficult to photograph, but hopefully you will be able to see the propeller take shape with each post.

[Mtskull]

I am only in the early stages of developing the shapes and dimensions for the T.6296......hopefully you will be able to see the propeller take shape with each post.

So, (hopefully this will also answer Dave’s question) is the purpose of all this to build a replica T.6296 propeller?

[Garuda]

Augmented reality app and T.6296 patterns.

That’s correct. It’s all in the title, T.6296 hub and replica propeller. Because I am in the early process of developing a T.6296 drawing and patterns, there really is not much to show. That will change of course as I progress. For the sake of clarity, yes I intend to build at least one replica T.6296 propeller. Hopefully there will be a requirement for more replica propellers in the future.

I have attached a screen shot showing how I projected the photograph of the T.6296 propeller onto the pieces of timber, from which I have been cutting the patterns. It does not line up exactly with the patterns I have made, but it gives me a very good idea of the shapes and dimensions of the T.6296 four bladed propeller. As I accumulate more evidence I will be able to construct an accurate replica T.6296 propeller. It would, of course be a lot easier if I had a T.6296 drawing. In 2011 I found an original T.6296 propeller blade. I measured it, because at the time I was also measuring my original Garuda propeller. I knew that at some time in the future, someone somewhere would have a requirement for a reproduction T.6296. About a month ago, I found the T.6296 boss photographed in the first post. The owner is in the USA, and he has very generously offered to send it over here so I can measure it. As part of the deal, when I send it back to him I will also send a set of pieces of machined timber which will allow him to construct a reproduction propeller. If I was to construct it here, it would cost a fortune to send it to the USA. There is also a museum in Queensland who are building a replica RE8. I made the same offer to them. Initially the project coordinator was very keen but more recently he has not responded to my messages, so I am not sure if they still require a propeller for their project or not.

[Garuda]

Overlay of printed photo of rear of T.6296 boss onto patterns.

When I clicked on the thumbnail screenshot of the photograph of the rear of the T.6296 boss superimposed onto the patterns I have been working on, I noticed that it is a very small file. I have subsequently cut the printed photo of the rear of the T.6296 boss out, using the half laps as a border and point of reference. The outline is slightly smaller than full size, and there is more distortion than I expected to be the case. Still, it gives me a very good idea of the shape and the dimensions of the boss.

[Garuda]

Jig for angles of laminations

When I measured the original T.6296 propeller blade in 2011 one of the key measurements I took was the angles of all the laminations of the propeller. There are eight laminations in total, and each lamination gradually rotates forward, toward the leading edge as the laminations progress from the rear to the front of the propeller. One of the other key reference templates I made was a tracing of the trailing edge of the blade.

[Garuda]

T.6296 drawing

This is the drawing so far. I have revised the boss three times so far, and I will revise it again if and when new information is provided, if it contradicts the information I already have. I found photos of a boss on this site which give the diameter as 2970mm. With the most current information I have, the 6 3/8” half laps measured on an original T.6296 boss give me an overall diameter about 1/2” short of 2970mm. Presumably the intended half lap width was 6 1/2”. The remaining 1/4” can be accounted for, assuming that the blades have shrunk by about 1/8” each over the last century.

[Garuda]

T.6296 tip

The first photo is a continuation of the photos posted in the previous post. It is the tip. As well as the original T.6296 blade I had access to an original T.6296 propeller blade tip. I have subsequently purchased another tip on eBay. It is very useful as a source of reference. I can work from the tip towards the boss, and now that I have good reference sources for the boss I can work from the centre outwards too. I will primarily work from the centre outwards. I have three Royal Aircraft Factory drawings, so I am familiar with the principles they used to design these propellers. Two of these propeller drawings are for four bladed propellers, and these drawings in particular will be very useful. I hope to be able to develop my own drawings for the T.6296 propeller, using measurements taken from T.6296 relics in conjunction with these known principles.

The second photo shows the original T.6296 propeller blade tip placed onto the forms I have attached to the revised drawing.

[Garuda]

T.6296

Some photos of the T.6296 tip in position on the revised drawing. Note, in the last photo there is a series of dowels. From other Royal Aircraft Factory drawings I know that the propeller blade sections are specified at the location of these dowels. They are usually spaced evenly, although in one of my Royal Aircraft Factory drawings they are not spaced at exact intervals. In the case of the T.6296 the dowels appear to be spaced 8” apart. The first line of dowels appear to be placed 7 3/4” from the centre of the boss. Once I correct the boss for shrinkage I suspect the dowels will move closer to 8” from the centre of the boss.

[Garuda]

The revised boss drawing. Note the much cleaner lines for the boss. I will probably revise the half lap width again from 6 3/8? to 6 1/2?. Hopefully I will be able to find an original T.6296 drawing, but 6 1/2? half laps give an overall diameter very close to the stated 2970mm. By extending each blade by about 1/8? I will be able to achieve the diameter of 2970mm stamped on an original T.6296 boss.

The second photo is of the jig for the angles of each lamination. It is sitting on the patterns I have made for the boss, and partial blades at various distances from the centre of the boss. The pattern traced from the trailing edge of the original T.6296 blade can be seen on the right hand side of the photo. It is also visible in other photos.

[Garuda]

Photos

Some photographs have just arrived, from my contact at the museum at Narromine. From the stamps it can be seen that it is an RE8 T.6296. At first I thought it was a BE2 propeller, but the stamps clearly read RE8 and T.6296. There are some inconsistencies with the boss in comparison to other T.6296 bosses I have studied. The diameter is less than 200mm, and all other T.6296 bosses I have examined are around 215 to 220mm diameter. The laminations and half laps are also inconsistent with other T.6296 bosses.

[Garuda]

More photos, RE8 T.6296

These photos confirm that this is a T.6296, and that it was fitted to an RE8. The tip has been doped in 1916 Scheme A PC10. Although the boss is stamped 1917, it is known that 1916 Scheme A PC10 was used throughout 1917 and 1918 in conjunction with later, much darker shades of PC10. There is an RE8 serial number on display in the same museum. It is mot known if the serial number was removed from the same RE8 as the propeller, and I will be very interested to see if it is also 1916 Scheme A PC10, or, as is much more likely the case a later shade of PC10.

[Garuda]

RE8 serial number C 2270

My friend sent me some more photos, including a photo of an FE2b propeller boss and a pair of Aldam Heaton propeller blade tips. I have posed photos of these in a new thread.

For anyone who is interested, here is the photo of the RE8 serial number I mentioned in the previous post. It has been removed from C 2270. It is difficult to tell from the photos if it is 1916 Scheme A PC 10 or not. It is certainly a bright green, as 1916 Scheme A PC 10 is, but it is darker than all 1916 Scheme A PC 10 samples I have seen. I know from one of my samples that this early version of PC 10 was varnished. Many samples are brown due to discolouration of the varnish. The underlying PC 10 is a light, bright green. The PC 10, if indeed that's what it is applied to the RE8 propeller blade tips is typical of the appearance of 1916 Scheme A PC 10 when the varnish covering it has weathered and discoloured. I hope to travel to the museum, and study these and all other WW1 aircraft related relics.