Ok so the 2m R is about 6' 8" 2.9 m radius is about 9' 7" I have many times run it on 10 ft radius and it is not a challenge, from the pics posted above it is safe to say 5 ft radius is out of the question. would guess if the track work was near perfect through the turn it might just make the 2m radius.. but I have never tried it. And yes that is my Mikado on the web site.
Jeff