The George van Brunt Scope (Formerly known as "The Mystery scope")

Here's a shot of it on the right with several other 8 inch Newtonian telescopes (and an 8" f10 Schmidt on the far left) for comparison (Click on any image to see a higher resolution version). 

As can be seen, it's a tall one for sure.

The tube is hand rolled fiberglass and sits about 6' tall and weighs about 10 - 15 pounds. It houses an 8" f7.9 mirror (measured) mounted in a Novak 9-point mirror cell.

I have a tripod mounted EQ-6 Equatorial mount but when the Roe scope was mounted up and the legs retracted to their minimum height, the eyepiece was too high to reach in most observing orientations. To solve this problem, I had about 6 inches of height removed from the pier that came with the scope. I also had an adapter machined that allowed mounting of the EQ-6 head to the pier. This has been an ideal combination for observing planets, double star splitting and compact deep sky objects at high powers. 

Here's the completed Rowe OTA with EQ-6 on the shortened pier on the right side of the image - the Mystery scope is in the background on the far right. Note that the focuser is right at eye level for me when pointed straight up. That means the eyepiece will always be accessible no matter where the OTA is pointed.

The Hupp Dobsonian mounted scope is shown on the left side of the image for comparison. On the far left is Lois Fitter's 6" f8 dobsonian mounted scope..

A Dobsonian base could be problematic as this scope requires a good deal of height for the altitude bearing. When coupled with it's weight, it means the base will have to be large and rigid (read heavy). The image at right shows the center of the altitude bearing for the Hupp scope at 28 inches above the ground. The same point for the mystery scope will have to be 35 inches above the ground. That doesn't give much room for the azimuth bearing and ground mount if the focuser is to stay at comfortable eye height for an average human. 

Performance

No observing has been done with this scope yet. Waiting for clear skies with excellent seeing

Initial thoughts

(Disclaimer: I reserve the right to change these thoughts at a moments notice).

Unless the optics are nearly perfect, this scope comes very close to being unusable. For an 8" f8 OTA, it's overly large, heavy and difficult to work with. Any mount is going to have to be correspondingly large and heavy. IF the optics turn out to have any quality, then this tube should be disposed of and the optics mounted in a smaller, lighter weight configuration. Otherwise, the associated hardware (mirror cell, spider & diagonal, focuser & finder) can be used elsewhere.

To take the best advantage of the optics, the mount should be driven. If portability is desired then this means either Dobsonian or pier/pier-varient mounted GEM. Any other type of mount pretty much requires a permanent home...

Updates

Dec 14  2016:

Performance

The skies cleared sufficiently on the 13th to perform some basic evaluations. The scope was mounted on the EQ-6G/pier. Temperatures were 20f dropping to 15f. Skies were clear most of the time. Seeing was 4/5 best but mostly 2.5/5. Heat rising from my body caused serious turbulence at the front of the scope. The moon was a few hours past full so there were some terrain features to observe at the terminator. What follows were personal notes put into an email to the group.

I'm out with it now and it's performing very well ... considering the seeing. The collimation is off a bit so the stars are a bit fuzzy. BUT they are clean and bright! Performance is typical of a long focal ratio 8" Newtonian telescope. 

Castor was an easy split and both stars looked uniform. The Trapezium is looking great at 321x. Unfortunately, the moon is blocking the e and f stars. I can tell though, that on a moonless night, they will be easily visible in this scope. 

Speaking of the moon, it is crisp and sharp from edge to edge in any eyepiece I use. Only a little soft at 321x. and a little more so at 459x. I am convinced this is due to moderate seeing and mis-collimation. These and the local, human induced seeing problems are masking the star test so I can't really report on that now. But I can say that no great aberrations are detectable at the moment.

This scope is working very fine.  I think these optics are a winner. As a Dobsonian, this scope would certainly be terrific for intermediate observers looking to try equipment at the next level up. It will work best in a driven mount but as it sits now, that would be reserved for the advanced-intermediate or beginning-advanced users - it's a beast in an equatorial mount.

Again, the only drawback I'm encountering is its length and weight. This can be resolved by shortening the tube and implementing lightening holes in the body itself - ala "The holy scope" mods as documented by John Duchek. Lightening the front 2/3rds to 3/5ths would have the added advantage of moving the CG back far enough for better operation in a Dobsonian mount. Shortening the front almost to the spider would decrease the weight more and also put the CG even further back. Anything that can be done to minimize the size of the dob base would be a good thing. 

As far as light intrusion caused by shortening the front end, a very lightweight tube extension (like a dew shield) could be used to block any stray light like Jim was concerned about. But that's only If we want to keep the fiberglass tube. Otherwise a smaller. lighter weight OTA could be built to house the current optics as is. Unfortunately, it will always be a scope with a 63" focal length so we can shorten the OTA only so much.

With regard to equatorial mounting, I rediscovered the reason I have finder mounts on either side of the focuser. It's been a while since I put a scope greater than F6 on this mount. This is the longest one yet and it's a real back stretcher for sure.

One of the first things I need to do for follow on testing is replace the collimation SCREWS with collimation KNOBS.

The only other thing that could be replaced is the focuser. This was a great design in its time but the friction fit for holding eyepieces still doesn't work well as it doesn't release eyepieces easily thus leading to unfortunate changes in pointing as force is needed to remove the eyepiece. 

You can forward this email to George with my thanks for the donation of a quality piece of optical work that can be used for years to come by beginners and advanced users alike. I'd like to know more about this scope especially any build details, mirror information, mounting and etc. Anything he can supply would be helpful including any photos he might have. He made a fine donation to the club and it should be documented.

OTA Mods and mounting options

This scope stands 70" tall. When looking at actual optical path length, diagonal holder height above center of focuser and the thickness of the primary mirror + holder, it looks like this scope can certainly benefit from removing 5" off the front and 2" off the rear. That would reduce the overall tube length to 63". A very lightweight light shield can be added in place of the material removed from the front.

Lightning holes can be added to the front 2/3rds or 3/5ths of the scope. This would have the added advantage of moving the CG closer to the back end of the OTA. This will reduce the height of an associated DOB base making its construction smaller and lighter. John Duchek documented lightening holes as a method of reducing tube currents in Newtonian telescopes a while back. See his work at "Holey Scope" and his follow on page called "Son of Holey scope"