R=T cot(i/2) where R is Radius, T is Tangent Length, and i is the intersection angle.
Of course, this is only going to hold true if the switch rails are also curved, and the other end of the curve ends at the frog point (which is very bad practise). As I said, #6 is not the same as 1 in 6. In prototype practise, you don't have 'radius' points/turnouts. --- In [email protected], "pickycat95" <pickycat95@...> wrote: > > OK. Most of that math is over my head unless I decide to stop and think > about it. I like the short answer better 1/N the ratio of divergence to > straight (short leg = 1 and long leg = N of a triangle). > > So, how does one figure the radius of the points? That can't be arbitrary. > > I'm interested because like Ed most of my turnouts are curved frogs - easier > to layout that way. But now I have one I'm about to build at could be a > straight frog. > Ben Trousdale > > --- In [email protected], "Gavin" <csowry@> wrote: > > > > It is. > > > > A #9 frog is 6deg 22min 02sec. > > A 1 in 9 is 6deg 20min 25sec. > > > > --- In [email protected], "Gavin" <csowry@> wrote: > > > > > > ..or is it 2 (tan 1/12 + tan 1/12), must look up the ARA specs. > > > > > > --- In [email protected], "Gavin" <csowry@> wrote: > > > > > > > > The British actually use 'straight' frogs, just like in USA, and here > > > > in NZ. It is the Germans, and some other European railways that use > > > > curved frogs. > > > > > > > > There is a difference between British/NZ and USA in measuring the frog. > > > > The geometric angle of a US #6 frog, say, is not the same as a British > > > > 1 in 6 frog. > > > > > > > > Off the top of my head, the British formula is tan 1/6, whereas the > > > > American is 2 tan (1/12 + 1/12). > > > > > > > > --- In [email protected], "Ed" <Loizeaux@> wrote: > > > > > > > > > > > Only "toy trains" have a curved frog. > > > > > > AbBaird > > > > > > > > > > As a general statement for American railroading that is true. > > > > > However, in England most real turnouts are made with a curved frog. > > > > > My NYC-themed layout has almost all curved frogs (and curved adjacent > > > > > rails) because I use White Oak Models turnouts sold by Kelvin White > > > > > who lived in Oxford at the time. Even though they are technically > > > > > incorrect for the NYC and other American railroads, I like them > > > > > because the longer continuous curve equates to a much larger "real" > > > > > radius than the typical American design with straight points/curved > > > > > closure rail/stright frog/curved rail past the frog. Thus, I find it > > > > > much easier to ease the 4-8-4 Niagara and other 8-coupled wheeled > > > > > steamers through a #6 turnout in the yards. Ken Reiter's SP 2-10-4 > > > > > also goes through a #6 turnout of this type easily. Yep, bending the > > > > > rule once in a while pays off. Cheers....Ed L. > > > > > > > > > > > > > > > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/S-Scale/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/S-Scale/join (Yahoo! ID required) <*> To change settings via email: [email protected] [email protected] <*> To unsubscribe from this group, send an email to: [email protected] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
