Reverse curve radius help/suggestions needed

[tynewydd]

On 16/05/2021 at 07:26, Pacific231G said:

An excellent idea and far easier than the mathematical formulae that MRN and MRC used to fill umpteen pages with.

I understand that a 30" curve with proper transitions will give far better running than a 36" curve without. Interestingly, 30"  for curves and 36" for points were the BRMSB recommended minima for 00 and H0 way back in the mid 1940s. They tended - especially nominally three foot radius points- to become the standard rather than the minima used by many modellers who built their own track thereafter. 

Similarly, XTrackCAD (always free) uses a Cornu curve algorithm for its flextrack tool that does real-time curve fitting to produce the smoothest curve in the space available.  You can drag the ends around or nudge connected tracks about and see the results in real-time.  Technically it is ensuring the radius varies linearly along the length of the arc which is the underlying characteristic of all smooth transitions. In the latest version, you can add fixed track pins at key points to allow "slewing" around objects as part of the overall smoothed result.  

It is true that transitions can be approximated by a series of fixed curves as well. For simple transitions that is easy. Things can be more complex to calculate as the number of constraints (angles and radii of connected tracks, desirable offsets) increases - so letting software take the strain may be easier. 

 

Adam