OK, another naieve question. The Steamlines Shay, Ted's Roundhouse 7/8th scale Porter, and the Frank S all have obvious plumes from the smokestack during cold weather. This Alisan Shay runs almost plume free. The pop offs offer evidence that steam is powering the critter, but only episodic plumes occur from the smoke stack and those usually when the engine starts from a stop. Any hypothesis occur to any of you, let me know. Is it a real efficient engine? Does the exhaust cool too much to cause a plume or could the exhaust be too hot and the steam dry?
Curious in Oregon Gary - Photos of Alisan shay look like the loco is cold except for the pop offs. http://www.angelfire.com/or/trainguy http://community.webshots.com/user/raltzenthor
