I think you will find your project challenging.
All of the surviving Grasshoppers have been heavily rebuilt, as you might expect from engines which had an operating lifetime in the 60-year range. They have extended frames, rebuilt boilers, major early components removed, new components added. So your best bet is to decided what period your model will represent. Mine (SMR) will represent the engine on early period mainline service (late 1830s). As such it will have things like a wood-lagged boiler, steam-powered forced draft, no cab and a tender. If you use the B&O's "John Hancock" display engine you will be building an 1890s tank-engine yard goat. If you decide to build their "Atlantic" engine, you will be building a "concept" engine, the "Andrew Jackson" rebuilt in 1893 to resemble (somewhat) the original Grasshopper, pulling some stagecoach cars which are fascinating but also represent a very brief, but colorful, historical reality. BTW, in addition to the engines in Baltimore, there is also one on display in Ohio.
The hopper's valve gear is very simple and operated by pedals (its really just a reverse mechanism), but overall the engine itself is very complex to model with many moving parts.
Have Fun!
If any of you plan to attend the York Meet next week, check out the various updates on SMR's Grasshopper project at our booth in Orange Hall, AA-01. I will also be giving a presentation of our new projects at the OGR Forum on Friday. See you there! Dave
PS: SMR is only building 65, MADE IN USA, hand-built brass models (both 2- and 3-rail combined). 41 are already reserved. Delivery this Spring. Priced less than many major manufacturer's China-built-by-the-thousands engines. Check out my web site, www.smrtrains.com for details.
