Not an ignorant question at all. I'm pretty sure these are the only locomotives around that have this set up.
That pipe is called a side stack. These locomotives have fixed valve gear so there is no way to reduce the cutoff. When steaming hard, the exhaust creates too much back pressure and too strong of a draft. The engineer has a valve that can vent some of the exhaust steam out the side stack, bypassing the exhaust nozzle.
ROGER CAN PROBABLY EXPLAIN IT BETTER BUT IT HAS SOMETHING TO DO WITH RELEASING STEAM PRESSURE WHILE GOING UP OR DOWN THE GRADE. THERE IS ALSO ONE COMING OUT THE CAB ROOF. ONE FOR UPHILL AND ONE FOR DOWN I THINK???
I finished up the engine today
The stack was changed to the new version and the cab roof and boiler fittings were finished.
I just remembered that I haven't made the safety yet so I will do it tomorrow.
It will run on a 50 foot point to point track just like the real one so it will need RC to reverse it at the top.
I am using a Ruby reverser which can easily reverse the four cylinders and also be used to control speed.
I finished the tender this week
The frame is brass with the wheel legs made from steel and CNC cut. They have a ridge around them like the prototype. the wheels are Shapways.
The hardest part of the tender is the upper fairing which tilts out on the side and rear. Looking at a photo of the prototype, I see that it is made in several pieces. I start by cutting card stock for the side and rear profiles and then make the transition piece by cutting out a cone section and trimming it to size. Then using the card stock as a pattern, I cut out the pieces in brass, bend the transition piece to make the cone section and solver solder the pieces together.
The deck is 1/16" flat stock. I have been using .032" sheet stock for my cabs and tenders lately as once it is annealed, it bends easily and the thicker material has less chance of oil-canning when it is heated up. the main body is made of four sections. the rear piece is rivet embossed on the ends and bent to shape around a steel dowel. The sides are rivet embossed on the top and the water legs are bent on a larger dowel. A bulkhead is then made to fit across the fron. Everything is soldered with StayBrite to make it water tight as the fuel tank will be in a water bath here.
I painted it yesterday and decaled it this morning. I am waiting for a battery box for the RC and will install the fuel tank after I mount it.