Spiral Baffle in a Cylinder

Date: 6/24/96 at 21:32:5
From: Anonymous
Subject: Formula for Spiral Baffle

I work for a sheet metal shop. We have a project a customer would like 
done, but we are unsure of how to figure it. We have a cylinder, 48 
in. dia. We would like to put a spiral baffle inside. What it
needs to be is starting from the top dropping 30 in. and making only 
one complete spiral. What would the radius be for the piece to 
accomplish this?

   Any help you could give would be welcome.

Date: 6/25/96 at 15:22:10
From: Doctor Anthony
Subject: Re: Formula for Spiral Baffle

You can calculate the length of the spiral by considering a right-
angled triangle, with base equal to the circumference of the cylinder 
(= pi*48) and height equal to the pitch (= 30 ins). The hypotenuse of 
the triangle will be the length of the spiral path (= L).  Using 
Pythagoras we have:

  L^2 = (pi*48)^2 + 30^2

      = 23639.568

    L = 153.75 inches.

I hope this is the dimension you were wanting.

-Doctor Anthony,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/