Need a little math help

[cudaken]

 I am trying to use the Atlas track plainer 8.0 what ever. It is being a pain but I will get the hang of it. Problem is turnouts and radius math.

 Lets say I want a 28 inch radius turn, I am using flex track in the program. What is length of the said 28 turn to make a 90 degree turn? I need the math so I can input it into the program. Program will let me use up to 70 inches sections even tho it only comes in 36" sections.

 Turn out for the program is all Atlas. It has # 4, # 6 and number # 8 if I remember correctly. What length of straight and then turn do I need to make the turn off track run parallel with the line it came off of? Need this so I plain a yard.

 In real life it is not a problem, I can lay rails. I need the math for the program it self.

 Thank you for the up coming answers.

                    Cuda Ken

[larak]

Hi Ken,

Part 1:

The circumference of a circle is related to its diameter by PI.  PI is approximately equal to 3.14 (3.14159...)

Diameter is twice radius so ... (hang on)

For a 28" radius turn, diameter = 2 x 28" = 56"

Circumference = PI x 56" = about 176 inches

Part 2:

A full circle is 360 degrees, 90 degrees is 1/4 of 360, so multiply 176 inches by 1/4 (or divide by 4)

Your length is  44 inches.

So,  Length = [radius x 2 x 3.14] * [degrees of curve / 360]

I hope that this makes sense and that my late night math is sound.

Karl

(Former owner of 11 second '68 charger)

[Weighmaster]

 Ken, (pi)x(D) divided by 4.  (3.1416 x 14 = 44.98").  That would be the centerline.  Add a couple inches or so for cutting errors and figure 48".  Gary

           
 

[loathar]

Yep, 43.98226"

(I can't beleive I remembered that from 25 years ago!)

[Last Chance]

90 degrees worth of 31 inch Kato Unitrack curve in HO scale will hold roughly 8 40 foot boxcars.

[Stevert]

 

cudaken

 I am trying to use the Atlas track plainer 8.0 what ever. It is being a pain but I will get the hang of it. Problem is turnouts and radius math.

 Lets say I want a 28 inch radius turn, I am using flex track in the program. What is length of the said 28 turn to make a 90 degree turn? I need the math so I can input it into the program. Program will let me use up to 70 inches sections even tho it only comes in 36" sections.

If you use the "Shape Flex Track" option under "Special" and just input the radius and the number of degrees, RTS will calculate the length.  If it's more than 36 inches, you'll have a splice in your curve. BTW, for a 90 degree curve with a radius of 28 inches, you'll need 43.98 inches of flex track.  

cudaken

 Turn out for the program is all Atlas. It has # 4, # 6 and number # 8 if I remember correctly. What length of straight and then turn do I need to make the turn off track run parallel with the line it came off of? Need this so I plain a yard.

The length of the straight is determined by how far apart you want the tracks to be.  Also, in order for the tracks to be parallel, the number of degrees you use for that curve has to be the same number of degrees as the frog angle of the turnout you're using (For example, a 9.5 degree curve for a #6, a 12 degree curve for a #4, etc).  It can be whatever radius you want it to be.  Again, go to "Special", but this time use the "Crossover/ladder" option and RTS will figure it out for you.  

cudaken

 In real life it is not a problem, I can lay rails. I need the math for the program it self.

 Thank you for the up coming answers.

                    Cuda Ken

Steve

[tomikawaTT]

One microquibble.  That 'not quite 44 inch' length is measured on the centerline of the track.  In HO, the outer rail of the 90 degree curve will be 44.5 inches long, while the inner rail will be noticeably shorter.

When working with flex track, it's a good idea to use the construction carpenter's 10% rule.  Measure out what you think you need, then add 10% for underestimates and flubs.

Can't help with your turnout question, unfortunately.  All of my turnouts are hand laid from raw rail.  (That's where some of that 10% flex track overage gets used up.)

Chuck (Modeling Central Japan in September, 1964)

[rrinker]

 If you mean you are using the Right Track software, you shouldn't have to input anything. That's sort of the point of CAD, you draw it and then afterwards it tells you how much material you need. Line up the turnouts how you want and adjust the piece of track between them to get the spacing you want. The Atlas geometry works rather welland depending ont he spacing you want, you often don't need any straight track to build a ladder. If you can find it, one of the older Atlas Custom-Line track plan books had a planner section in the back showing various arrangements. I don't know if their newer books have the same thing.

                                       --Randy

[Texas Zepher]

Stevert

, in order for the tracks to be parallel, the number of degrees you use for that curve has to be the same number of degrees as the frog angle of the turnout you're using (For example, a 9.5 degree curve for a #6, a 12 degree curve for a #4, etc).  ..., but this time use the "Crossover/ladder" option and RTS will figure it out for you.

And a more important reason to use the tools built into RTS is that Atlas #6 is not a true #6 and Atlas #4 is not a true #4.   Atlas #6 is closer to #5.75, and Atlas #4s are closer to #4.75.  So in this case, without knowing the true frog angle, the math for #4 and #6 would give inaccurate results.  This is also why Atlas has some apparently strange degree crossings - they are designed to be used with the custom line turnouts.

[rrinker]

The #4 is th emessed up one, it's really a #4.5. The #6 is a #6, it's not tighter than 1 in 6.

                 --Randy