Seeking info on height measurement increase (preferably a formula for arcs containing rise over run) for helix construction. I need to know what the change is, at specific degrees , I know the formula for calculating distances between points on an arc but due to design constraints that restrict maximum distance at 18.9 inches between supports, I cannot determine rise over run for exact placement of the supports at specific points in the arc.
Is the calculation and measurement of specific points of a straight “rise over run” the same on an arc of the same length and rise???
Does the fact that the line curves affect the rise in the construction of a helix in regards to model railroading??
i.e. “sea level” is at 40" and an arc of 30" outside radius rises 4" in 360 degrees with supports at 18.9" (19") what is the change in height at 19" increments along the arc?
Thanks
Assuming two things -
- I still remember the circumference of a circle equation
- I can still divide…
You will have a 188.4" long circumference of the circle. Rising 4" over that distance is a little over 2.1% grade. 188.4 divided by 19" is 9 (roughly, I’m rounding down). You’ll have a support every 40 degrees or so, provided I’m using the right formulae for circles…
So, with 9 supports each creating/supporting one 40º segment (which is 19" long), you will have a rise of 1/9 of 4" from one endpoint to another…
I really hope that my math (and logic) is correct on this, and points you in the right direction… circles/arcs were never my strong point…[D)]
thanks but i have found the answer staring me in the face. I was attempting to get a measureable number for each point when i really only need to go half way around the axis and measure 2" and then set the line for the grade. and transfer that to the 30" point
your math is right , i had that part already. that is how i determined the 18.9" (19") distance on the arc… i started with an octogon center and that gave me easily divided points but that gave too much distance on the arc so i had to go with a different polygon
very good then. At least I wasn’t completely wrong.
Good thing you got the separation/rise figured out. Sounds like this is gonna be a monster…
if this idea works i will single handedly revolutionize the helix industry. it will have ease of construction and simplify installation of track by allowing track to be installed before the helix is placed.