(erielack) re #3903; Moscow Signal; Curve Radii

[harebridle_@_aol.com]

To List;The still photo at Moscow shows loco #3655, in 3/75.

So the "modification" to the lower sgnal head pre-dates Conrail.

Years back, I calculated some data on curve radii.

Civil Engineers plan curvatures in Degrees, Zero being tangent.

Modelers plan curves radii in Feet or Inches.

A 16-degree curve has a radius of 358 Feet;

A 17-degree curve has a radius of 332 Feet;

if you take each of those numbers, divided by 87, the ratio to HO Scale, and multiply by 12, you get their radii in Inches. The result is between 41 and 49 inches, IN HO.

Also of interest, the Prototype Speed Restriction over the diverging movement of a Turnout, or Switch, is derived by doubling the Frog Angle, plus One.

Thus a #7 switch would have a speed restriction of 15 MPH.

A DL&W Employes Timetable I have shows several General Speed Restrictions; a train moving thru sidings is restricted to 15.

Using DCC, my speed curves include that speed in one of the speed steps.

Another step is a safe coupling speed, ALWAYS less than 4 MPH.

Watching the prototype switching cars, they normally stop before coupling to a standing car.

I try to derive realistic Acceleration rates, too. A good start is 1.5 MPH per second, that of a DL&W MU set.

Steamers, and most Diesles, were not as quick.

You would be amazed at how much more realisticly my stuff operates.

No Fast Clocks!

It may be good practice to have a tangent between adjacent cross-overs, to avoid an "S-curve," but I have found that by  putting the points of adjacent cross-overs as close together as possible, the problem disappears, especially at slow speeds, with cars weighted to NMRA figures.

73's, Charlie Gerow


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