Phase 2: Will a helix help in a tight spot?

The outer loop eventually go out to the front yard (throught the wall in the distance) and cross the driveway and continue around the house.

But for most running, I want it all secure and out of sight in the back yard.

Now,  the problem is how to get the track at 21" here back down to the ground? We have gone through the planter and past the fireplace, here's looking back East.

The track continues to climb through the planter (all the way to the back left in this picture) and behind the fireplace and then levels out on the left, where the planter gets close to the wall.

Looking West at the same "wide spot" where the helix might work

There's not a lot of space, but a helix came to mind, so I mocked up something to check it out.

Refining the idea

OK, so I think it might work. Now to make supports to the actual grade, have to tie it back into the main line on the ground.

It took a lot of balancing, and the Aristo joiners are getting pretty tweaked. Looks doable. The track is 8' diameter, and it's pretty close.

I used a 10 foot diameter switch to the main line:

At this point I took Aristo HW passenger cars, USAT streamliners, and container cars by hand (very carefully!) down to check what clearances I needed. I measured 4.5" from the outside rail. Tight, but they made it!

Add rail clamps and test!

OK, add a whole bunch of Split Jaw SS clamps. I actually ran a USAT F unit down and back up this!

Being a little fearful, I took 2 Aristo heavyweight cars coupled together and rolled them down, they worked, although the track flexed enough that the undersides touched the rails a couple of times. Same for the full length USAT streamliners.

Final decision: not the best solution

Looking at the grade and the curvature required, there was just no way long trains would go down this and up was impossible for more than a loco and a couple of cars.

It also completely obstructed the walkway. I did find a better alternative, but this was a good exercise. It could be done in about 8 foot, and would allow short trains with short cars to go down.