Mercedes DIII engine

[William Reese]

Does anyone know the method of fabrication of the Mercedes DIII intake manifold and what material it was made from?

I also assume that it has a lip on the carburetor side so that the large nut can be screwed to the carburetor, thus securing the pipe.

Thanks!
William Reese

['14-'18aviationcollector]

Hi William,

I certainly wish I could help you more, but from memory it appears to be a series of bent steel tubes, although I can't be certain that they are steel since I am only relying on memory. I am just in the process of trying to find some of my photos, so I can't confirm this, but my memory of the larger diameter tubes / pipes is that they are pressed and are two halves welded together, but please understand that I might be wrong!!

A lip on the carburettor side? Do you mean where the pipe screws onto the carburettor, or where it screws onto the cylinders? I assume you mean where is screws onto the cylinders. I believe there is a steel ring welded onto the water jacket. The ring has a thread on it, and the large nut screws onto the threaded ring. On the carburettor, I believe the thread was machined out of a lug on the carburettor housing. I hope this helps!

Regards, David.

[William Reese]

Hi David,

Thanks for the reply! Please look at the Mercedes DIII engine at the Budapest Aviation Museum at Mercedes Diii aviation engine at Idflieg - A Place for Surviving Machines. It has cutaways on the engine.

Notice the intake manifold cutaway. Could it be a two piece aluminum (it looks aluminum in color) castings welded were they are perpendicular to each other as I can see a weld joint there. I can't see any other weld joint other than the valves welded to it.

It seems to be thicker than a pressed steel piece. I also don't see a welded seem were two steel stamping halves could be welded together. Any thoughts?

William Reese

[Ransom E. Olds]

My impression is generally in agreement with David here, that the manifold was welded up from steel pressings. The earlier D.II intake manifolds appear to be fabricated from copper tubing and perhaps the D.III made originally were too. It seems to me (speaking from a position of practical ignorance) that producing satisfactory manifolds from welded thin-wall aluminum castings was beyond the technology of 1917. Ransom

['14-'18aviationcollector]

Hi William,

The Budapest D.III is very impressive! It is a great shame that it has been cut to show sections, but it really does show some fantastic detail! I would love to go and see it! ... if they would let you take measurements I would be especially interested to see it! I still tend to think that the intake manifold is weled steel pipe, but I am just going from memory. I have spent a lot of time studying the D.III close up, and my memory is that the pipes feel like steel, but I could be wrong of course. I tend to agree with Ransom, I doubt they had aluminium tubes, and the ability to weld them. They were struggling even with aluminium alloys at that time, and I think that aluminium tubes bent and welded are very unlikely, but I could be wrong! The basic drawing that I have seems to be different to the sectioned engine. Maybe the D.IIIa, which is probably what I studied - I am not aware of the differences between the D.III and the D.IIIa - had the extra larger diameter pipe welded over the to pof the smaller diameter pipe. I think this was a water jacket, to cool the intake pipes, and this is the part that I thought was two pieces welded together, but I am just going from memory, and the D.III photos you provided the link to does not seem to have this extra pipe. I believe the pipes you can see in the photos are simply bent and welded to each other. I think that even though the pipes are bright, and they sure do look as though they could be aluminium, I am reasonably sure they are steel. They might have been polished, and in fact there seem to be machining marks of some sort on the inside of these pipes.

The first photo illustrates the flange with the thread welded onto it perfectly! You can see it very clearly, and it is sectioned, cut in half.

I hoope this helps! Regards, David.