# Radius Q



## NTCGRR (Jan 2, 2008)

I one inch scale
80ft radius circle will need how many lenger ft of track?

I come up with around 500 ft???


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## Ted Nordin (Feb 27, 2008)

Darn close: Using circumference = Pi x Diameter = 3.1416 x 160 = 502.7 feet. Of course 2 rails = more $ than I have and also less arthritis. Ted


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## Semper Vaporo (Jan 2, 2008)

Circumference is Pi times the diameter (no matter what the scale!)... so 80-ft radius is 160-ft diameter ... times Pi (3.14159+) equals 502.6548-Ft 

If you are in 1-inch scale, that means 1-ft in the real world is modeded as 1-inch... or put another way it is 1/12th scale (1:12), so divide either the 80-ft by 12, double it to get diameter and multiply by Pi, or take the above answer (in real-world measurements) and divide by 12 ... both equal 41.8879-ft, or 41-ft 10.65-in. 


EDIT: I should add that if your 80-ft is your model radius then multiply by 12 to get the real-world radius that is being modeled... 80-ft * 12 = 960-ft and 502.6548-ft * 12 = 6031.86-ft.


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## chuck n (Jan 2, 2008)

Marty:

The formula for the circumference of a circle is: C = Pi x diameter. In your case with a diameter of 160' the circumference is about 503'. Pi is equal to 3.1416....

Chuck

WOW when I started typing no one had responded. When I finished I was #3.


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## armorsmith (Jun 1, 2008)

And 503' X 12 scale feet to the foot equals 6036 scale feet or a bit over a smile (scale mile). BIG circle!


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## Paul Burch (Jan 2, 2008)

So tell us what you are planing Marty.


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## Totalwrecker (Feb 26, 2009)

Crop Circles????!!!!! 


ha ha


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## Steve Stockham (Jan 2, 2008)

My guess is that he needs 1006 linear feet of track. 1" scale aluminum track. I'm not sure what the current rate ($$/ft.) is but it had gone up considerably from when my father last looked at it!


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## Jerry Barnes (Jan 2, 2008)

Maybe he will run a line into town and we can ride the train out to his open house!


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## NTCGRR (Jan 2, 2008)

woow 
thanks for all the tips. 
almost a scale mile, cool. 
I need to see how much room it will take in the south two acers. 
Just thinking tring to get a deal from Kidmans. But Accu does not deal to well. 
I want to be able to run my Geep here at home. It run s great on the clubs bad track, but here its too tight for it. 
To be honest I took a scale ruler of1/8" made an 80ft 1/4 circle and then took the ruler and moved it around the edge..


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## Totalwrecker (Feb 26, 2009)

Area = pi r squared .... A = 3.14 x (80x80) 

There will be an eager beaver along soon with a calculator.... 

John


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## Semper Vaporo (Jan 2, 2008)

Posted By Totalwrecker on 19 Jul 2012 11:00 AM 
Area = pi r squared .... A = 3.14 x (80x80) 

There will be an eager beaver along soon with a calculator.... 

John 

NO NO NO!!! Pie are ROUND... Der Corn-bread are square!


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## Torby (Jan 2, 2008)

But her wants the circumference, not the area. The first answer is right 2 Pi R


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## aceinspp (Jan 2, 2008)

Pie is not always round as the case with a pie square pizza.







I agree with Jerry need to get that train into town so we can rideit out to the house enda and not drive are nice cars on a dirty old gravel road. Later RJD


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## NTCGRR (Jan 2, 2008)

drive are nice cars " 
our??


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## Totalwrecker (Feb 26, 2009)

Marty... it's hard to teach an old guy to 'text' 

Todd, 2nd post says he wanted to know how much od 2 acres that circle will take. 
Sounds like Area to me! 

Happy Rails, no matter how big! 

John


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## toddalin (Jan 4, 2008)

Posted By Totalwrecker on 20 Jul 2012 02:43 PM 
Marty... it's hard to teach an old guy to 'text' 

Todd, 2nd post says he wanted to know how much od 2 acres that circle will take. 
Sounds like Area to me! 

Happy Rails, no matter how big! 

John 

Then wouldn't the area be the ~503 feet x 0.67 feet (8 inch ROW) / 43,560 sq ft /acre = 0.0077 acre (or 337 square feet)?


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## NTCGRR (Jan 2, 2008)

I just give ol RJ a hard time. He sends it right back. 
thanks all. 
IF it ever cools down I will take the transit out and shoot in a couple of areas and see what the grade is. 
I can use my old circle for a bike trail like in 1:1s.


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## NTCGRR (Jan 2, 2008)

50' rad , 1/4 circle of that is about 76ft of track?


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## Semper Vaporo (Jan 2, 2008)

circumference is Pi * the diameter, so a 50' radius is a 100' diameter... times Pi is 314.16' circumference. 1/4 of that is 78.54'


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## mickey (Jan 28, 2009)

A little more precise please.....;-)


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## Semper Vaporo (Jan 2, 2008)

Posted By mickey on 06 Aug 2012 08:22 PM 
A little more precise please.....;-) 

(Sigh!) 
100' * 3.141592654 = 314.1592654' / 4 = 78.53981635' = 78' 6&31/64" of "track"

The inner rail will be 78.48254773' = 78' 5&49/64"

The outer rail will be 78.59708500' = 78' 7&11/64"

Conversions to fractions of inches are just approximate to the 64th of an inch.

Of course this does not take into account a thermal expansion gap between rail segments because I don't know how many gaps there will be, which will be based on what lengths of rail are to be used and if some segments need to be cut to insert a switch or other track appliance, so the actual length of rails used will be less than the calculated value.


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## NTCGRR (Jan 2, 2008)

Thank you


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