bob2 posted:Compare the wheelbase of the 5 axle casting with the wheelbase of even one Challenger engine, let alone an 80" drivered Northern. The tender was not the limiting factor. My Challenger tenders can go around far sharper curves than their locomotives can.
BIG difference in the tolerances of models compared to the 1:1 scale trains. The UP steam program has learned that lesson many times over the years that even though the engine can make it, the tender can get you into trouble, most famously with a wye in Kingsport, TN when the 3985 came east to pull the Clinchfield Santa Train some years ago. The engine made it around fine, the tender not so much. Long moves of towing the engine backwards ensued.
Model train physics and tolerances are a totally different animal, and rarely have any relation to how the real thing performed.
