Sunday, 10 January 2016

Aspiration and Inspiration

Apologies, gentle reader, for the recent dearth of posts. I have been rather busy of late with non rocket engine related activities. However, I have managed to get a few hours in the workshop here and there. 

A brief summary of practical activities that have been progressed:-

Cutting jig completed and adjusted to cut square

New ER32 collet chuck in process of being fitted to backplate

I am also in the middle of writing an article on the automated indexer for the British magazine "Model Engineer's Workshop". If you are in the UK, do look out for it.

As for the aspirational and inspirational content of this post, read on...

I expect you are probably wondering what I am going to do with all of those tubes. Well, here is the photograph that provided my original inspiration:-

This frankly beautiful little tube bundle engine was built in 1970 by Maschinenfabrik Augsburg Nurburg (MAN) of Germany. I discovered it on the website of the Deutsches Museum. Sadly, there is very little information outside of who built it and when. My best guess is that it was some sort of technology demonstrator, and is of brazed construction. There is no information regarding what the propellants were or if it was ever fired.

The next two pictures come from the Smithsonian Air and Space collection in the US:-

This experimental thrust chamber was made by Reaction Motors in the US, in about 1947. It is reckoned to be the first attempt at tube bundle construction. I like this photograph because it shows exactly what I want to do. You'll notice that the tubes have been crimped or "booked" at the throat. According to the information provided, the construction is welded stainless tube. Obviously in a device that was intended to be fired the welds would need to run the full length of the tubes to provide structural integrity. Strengthening bands would also be required, like this:-

This chamber was built by Aerojet in 1948, and apparently was arrived at in isolation from the Reaction Motor's development. It is a much more complete effort, with manifolding at the head end and strengthening banding. Just look at the tube bending that has been employed to turn the fuel back towards the head end at the exit; it is almost like basket work! Also note the booking of the tubes at this point. There are no details of construction but I suspect this is brazed. Oddly the brazing does not appear to extend to the full length of the divergent section.

I would really like to learn more about these motors. If anyone out there has any more information I'd be glad to hear from them.

Progress is slow, as always. Finding these images has spurred me on though, and when you can see your goal it is generally easier to achieve it. Keep checking in for updates, and thank you for your continued interest. 


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  2. Some fascinating work going on here and thanks for taking the time to write it up. That can almost be as time consuming as the multiple tangents you've had to take to make the correct tools!

    I enjoyed reading of your efforts and also seeing the pictures. Do keep up the good work and let's hope to see some more progress this year!



  3. Hello Mark,

    Thank you for taking the time to follow my efforts and to comment on them. I am hoping that things will progress a little more quickly this year. The tool builds are not quite over yet, to stand any chance of success I have to get that part right from the outset. I firmly believe that every obstacle yields to persistent effort. Do keep watching,

    British Reaction Research.