N track

[James Marshall]

what size/type curve track do I need to go outside and inside the 'standard 24" curve that comes in the N guage sets?

[brokemoto]

When you state "standard 24", I am assuming that you refer to the diameter of the oval.   As a rule, one refers to the radius of a curve, rather than the diameter.  One determines the radius by measuring along/around an imaginary line down the middle of the track piece.

B-mann usually puts its 11,25 inch radius E-ZTRAK in its sets.  That is the sharpest radius curve that B-mann has in production.  If you look elsewhere on this website, you will see what curvatures that B-mann sells.  Off the top of my head, I know that B-mann sells seventeen and fourteen inch radius track.  There may be others, but I can not recall them right now.

If you must have track-cum-roadbed, Kato does sell UNITRAK in curvatures sharper than 11,25 inches.  The old standard nine and three quarter track will go inside the 11,25 inch loop.  Due to overhang, however, you may have clearance problems if you try to operate two trains at once.  Kato does sell track with curves that are sharper.  Do keep in mind that the sharper the curves, the more limit on what you can run on them.  If you go, say, to an eight inch radius curve, you should not have any clearance problems, but you would have difficulty operating anything other than small power and rolling stock.  Larger power and rolling stock is more likely to climb sharp curves, derail or stall due to broken electrical contact.

If you do not need to use track-cum-roadbed, you can buy cork and either flex or sectional track.  Various manufacturers offer those.  B-mann at one time did offer sectional track in nine and three quarter radius (without the roadbed, mind you) but I understand that all of that is now out of production.  You will find it out there, still, though, either at shows or in some stores as NOS.

If you plan to use turnouts to make crossovers between loops, be aware that the E-ZTRACK and UNITRAK are not compatible.  They use different rail joiners and their construction is such that the pieces do not mate well.  If you want to use those two on the same layout, you must use a transition piece of sectional or a cut off section of flex.  It takes a bit of work.  I have done it, and, done it successfully, but, if I had it to do again, I would find another way.