Radius calculation

[Brickie]

Hi all-

Does anyone happen to know the formula for calculating the radius of an arch armed with just the span & the rise?

I know I learned it at college but damned if I can remember!

[PeterW]

Are you looking for a parabola or a perfect segment...??

[AliMcLeod]

Does this help?

 

http://www.mathopenref.com/arcradius.html

 

 

[SteamyTea]

Or part of an ellipse.

Draw it up in CAD

[Brickie]

The arch former forms a segment,I suppose?

I have an online calculator,just wondered if anyone knew in case I ever need to do it where there's no mobile signal!

[AliMcLeod]

  On 06/09/2017 at 12:33, Brickie said:

The arch former forms a segment,I suppose?

I have an online calculator,just wondered if anyone knew in case I ever need to do it where there's no mobile signal!

Expand  

 

The link i gave above has the formula.

[Brickie]

Great,thanks. 

[SteamyTea]

Does this work.

Not tried, but it may work off line if you save the page and then open it in a browser.

 

https://steamytea.wixsite.com/radiuscalculator

[Temp]

I couldn't get that to work but the equation seems ok for the trivial case of H = 1, W = 2