About 20ft radius. there are probably some recommendations somewhere from eg the Southern Federation but I recall G1 suggest 10ft radius. That's why people formed clubs with communal tracks – not many people have a big enough garden for their own track.

BR/GWR absolute minimum curvature for dock lines was 2 chains which scales down to 8 ft 3 inches . Only little 0-4-0 dock tanks usually ran on these lines though some 0-6-0 engines with very short wheelbase could scrape round .

Bit of data from running experience – a 5 inch Speedy will scrape round 15 ft radius layed to 5 inch gauge true and run very easily on track with 1/8 inch gauge widening .

Gauge widening whilst not ideal does allow some engines to run on tighter radii than they should .

Where there is no alternative to running on very small radius track there are usually ways to modify the engine to make it more flexible and run more freely . In case of an Atlantic arranging a lot of side movement on trailing wheels and bogie will certainly help . An extra +/- 3/32 nd inch could make all the difference – though there are usually practical limits to what can be achieved before wheel fouling becomes a problem .

MikeW

MikeW

At tentative YEZS for Micheal though not exactly the same. In the early days of steam engines there was a loco built to run around a small circle of track which had wheels on one side smaller than the other.

Ryan … Work out the difference in circumferance of the inner and out rails of your proposed circle of track .. the other idea is to have flangeless middle drivers. New Zealand Government Railways did this for thier P class 2-8-0 locos designed to operate on tight curves with just the first and fourth wheelset had flanges.

Forget about camber for wheels helping as I worked it out some years ago when my Club organised a portable track and to exagerate because I forget the exact details you would need 45 degree camber. It works for the big railways but just copycat modelling for scale versions.

Finally forget about live steam and run diesels with their bogies No NEVER!!!

Though the original Garrett was an 0-4-0+0-4-0 I think. Read David Joy's 'Engines that Bend"

EDIT re read the question and see you have your loco

Edited By JC Uknz 1 on 30/06/2013 04:31:36

Edited By JC Uknz 1 on 30/06/2013 04:42:03