I am using mixed radius with no problem. In fact I also have an area in a steel mill where I have 12" radius curves and encounter no issues. A SW1500 and GE 44 tonner make the turns just fine.
If you can support an additional foot in width, most of your problems go away. I have an area that is 5" wide and run a double track turn around it with no problem at all. Designing in an extra foot makes a world of difference- but if you are committed to a 4x8, you can certainly run decent sized gear.
Mike Habersack http://rail. habersack. com
Maryland - the land of pleasant living...
On my N scale Kato unitrack layout the smallest radius is 19'' which is about equal to 38'' radius in HO scale . Six axel diesels look great , so do my 85' california zephyr pass cars. My largest and most common radius is 28'' or about a 56'' radius in HO. How often do you even see anything close to this in HO?
It looks so much better with larger radius curves. That is one of the main reasons I am an N scaler.
N Scale Diesels......I like 'em
My Proto 2000 E6 runs fine on an 18" radius, but when the Walthers heavyweight passenger cars box says "minimum 24" radius", you better beleive it.
I did the same as you did. I purchased a track plan book and ordered the material list from the manufacturer. This layout worked ok for a beginner but when I wanted to upgrade my 40 foot cars to the 50 foot and longer and also use 6 axial locomotives I found only a few locomotives would work without derailments from time to time. I believe the only 6 axial I had that would run good on it was the old athearn SD45 which was shorter than the SD40-2. after a few years of frustrating derailments, I almost gave up model railroading. I would suggest that you do at least 22" radius and would recommend 24". That way when you decide to get the longer cars down the road (and you will) you will have a layout that will run them without derailments and the frustrations will not be a factor in you giving up on model railroading.
Good luck
Eddie
Cat375 - I have had a 4x8' layout and run my Atlas Trainmaster (a long 6-axle engine) through the 22" and 18" radius sections with little trouble BUT find that the #4 Atlas switches that I used were trouble.