Thanks for the input Kenneth. I know that I will be stretching the possibilities if I decide to put airstrip on the layout. I may abandon the idea of an airstrip in the middle and just go with a military base. I guess, I have to create real size (n-scale) version of the layout and see what I can actually fit in.
This looks like fun to me! A couple box cars, flat car, maybe a TOFC, a GE 44 or 70 ton loco, some fuel tankers and you're in business. Perhaps a cassette to stick on the end of the "interchange" spur to give a little breathing room there. Also, perhaps a small shed on the end of the switchback and fuel tank for servicing/storing the engine.
The runaround on the end, and the switchback, do a lot to add to what would normally be considered a substandard size. Because the switchback and the fuel depot are 'opposite points', train direction and the runaround must be used. Add the fact in that you probably only have one locomotive and one car headroom on a two car siding at the freight house, and it becomes at least a mild challenge beyond just running in circles. I think with a military theme I'd be tempted to put a heavy equipment circus ramp in there somewhere for tank loading. Armor on trains and parked armor is always an attention-getter, and there's some pretty nice nice N models out there. If you want to see 'track gone wild' go onto either Google Earth or MSR Maps and study the track out at Bellemont, AZ (Santa Fe) at the Navajo Munitions Depot, there's every imagineable oddball track configuration out there in the middle of nowhere for munitions storage and loading. At least on something like this, when you get out from under the bed (literally) you'd have a very nice little module to incorporate into something bigger, you wouldn't be wasting either time or money.
The Bachmann Peter Witt streetcar, GE 44 and 70 ton radius limit is 140mm(5.5in). The Brill and PCC do the 103s. The N-Cat group have done a lot of box and steeple cab conversions on the pair. For a long time the Chicago Municipal Airport had a rail line crossing it through the middle. The two main runways and the taxiways were all crossed on the mile square airport. The rails are gone today and the runways are still just over a mile long but the name has changed to Midway International Airport.
I have done some measurements yesterday and looks like the layout is going to be a tight fit. The work area on the box cover is exactly 15 3/4". The extended layout is 17" wide. I do not have the Kato Unitrack yet so I am relying on SCARM's design. It looks like in the software, there is about 0.7" space between the end of the layout and the actual track. If that's the case, then I should be able to fit the track that goes to the edge. If not, then I may need to go with the 6" radius or drop the extension track.
Here's the plan I did with Tomix track done with Unitrack... It requires the use of three pieces of 6" radius track in order to pull it off. I believe there is just enough room for a 44-tonner and one 40-foot car on the switchback.
I am having fun just designing the layout. Can't wait when I actually start putting the track together. Anyway, I did some calculations and the extra track in the lower left corner is not going to happen with 7" radius. Not enough space. So either I go with 6" radius and have the extra track or I go back to my original layout with two turnouts for station and depot only. Leaning towards dropping the extra track as I do not want to go tighter than 7". Here is something else, I was thinking of. It has 7" and 6" ovals with crossover. That though, may be beyond my capabilities. Running two trains would be nice but with such limited real estate, I will be left with little to no space to put any buildings. Plus I wanted to keep this simple and budget friendly. The crossover alone is more than $50.
Two oval loops, two trains? Why? It might be reasonable to have one line representing a mainline railroad and the other the track the on-base switching line. You could have a mainline train leave cars for the on-base switcher to spot. HOWEVER , in your size layout, it would look like the trunkline (outer) never gets off base, never goes anywhere. In a small layout, it might be better to concentrate on either the mainline rr or the base rr. In the case of the base railroad (which my blimp base railroad exemplifies), the stress is on the base railroad, and the trunkline nis represented only by a dummy connection. The other alternative is to represent the trunkline and have one or two base spurs that are switched by a mainline engine. Here is a small layout I designed with only 6 turnouts. It represents a port switching railroad that also switches one spur to a military base. (Also includes a "yard," a port scene and a big grain elevator.) This is somewhat bigger than your plan and does not do as much with the base. This plan does include a scenic background divider to make twice as many scenes, but it requires them tom be represented with background painted pictures and with structure specially built to be viewed mostly from one side. You might consider an oval that represents a mainline railroad with a spur into a base at the front. You could have the BACK track of the oval hidden, not in a tunnel but behind a row of building FRONTS. Those fronts might be big airplane hangers, two or three of them, each 6 or 8 inches long and 3 inches tall- whatever fits in your box. That row of building fronts would be one inch in front of the back tracks, and only be maybe 1/16 of an inch thick. That provides an illusion of BIG base buildings. An apron for airplane would run in front of them, a place to display airplane models. The front half or two-thirds of the layout would be fully-modeled supply buildings, barracks, fuel dump, etc. A mainline train could run from "somewhere else" (from behind the background), come onto your base, switch and then go on somewhere else. Of course, there are also trains that just go BY the base. A very realistic display that "does something." One other note: The scissors double crossover is something that would be seen on a very busy mainline, or an extremely congested switching area. A single crossover made up of two turnouts ought to suffice here IF you were to use a double oval.
Actually, scissors crossovers are usually only seen on commuter lines and light rail; they're almost never seen on freight lines. I might also add that the OP has indicated the absolute maximum layout dimensions are 17 x 33.
Thanks again for all the input. After all the good reading you guys provided here, I have decided to go with this simple layout: It basically covers 100% of the available space and has the 7" turning radius. Sorry no space for a track that goes outside of the layout. That of course unless I go with 6" turning radius which I am trying to avoid. This layout is featured here: http://www.cke1st.com/m_train2.htm (plan: 30x21_1). The only thing is that I think I am going to drop the idea of creating military base. Couldn't find buildings from WWII era. I wanted to go with paper models for the buildings and only found airport base which is too big for this layout and German camp from WWII. I have also talked to the kids and they agree to go with a small town (couple of buildings in the middle of the layout), train station and one industry (at the ends of the turnouts). We are going to use the Kato Unitrack which has the built-in roadbed. Just to make things simple for a beginner like me. I still need to learn a lot about model trains as even some of the terms you guys used are new to me. I think if I stick with a simple layout and do most of the scenery from paper models, it will be a good first build that may not destroy my budget.
