In another thread, I am exploring sliding Newtonian ideas, with the goal of refactoring the OTA for my existing 8" dob. In THIS thread, I will be detailing the build of a new scope that is based on Mel Bartels' amazing (IMO) work on fast RFTs using meniscus mirrors. My goal is to replicate his 13.2" scope (detailed here), in a slightly larger, and faster format: 14" @ f/2.8. I am really excited by these scopes because, as I mention in my other thread, I am hampered by portability and with these very fast designs, I can have a highly portable instrument that is also of substantial aperture for (hopefully) excellent viewing.
For the last few weeks, I have been immersing myself in the design, trying to understand its nuances, and getting my head around the various stages I will need to go through. Fortunately, Mel has been extremely generous with his time and advice, and has been willing to answer any questions I may have. So at this point, it is full steam GO.
Of course, the scope all starts with the optics and, specifically, the primary. If you are familiar with these scopes, they feature very thin primaries and achieve their fast curvatures by being meniscus mirrors, like a contact lens with an aluminum coating. This enables them to have relatively deep sagittas, while retaining a constant thickness of glass, giving them surprising strength for their low mass compared to normal mirror blanks. Additionally, the mirrors use plate glass instead of pyrex, to make them substantially cheaper to fabricate.
So my story will start with the primary and note: this is an in-progress build thread. I am only just a few steps down the path, and will update as things change. I have a bit more to say now, but it is late from a long Thanksgiving weekend, so I will continue tomorrow on the fabrication of a meniscus mirror.