----- Original Message -----
From: Al Gietzen <ALVentures@cox.net>
Date: Friday, October 24, 2003 12:46 pm
Subject: [FlyRotary] Re: radiator tube sizing


> Maybe better check your flow rate units; gpm vs cfm.  20 cfm is
> way too
> high.  For a 2-rotor you'd probably need a max of around 25 gpm, which
> is about 3.5 cfm.


In the immortal words of Homer Simpson:  DOH!!

Here is revised data using an absolute minimum flow rate of 20'g'pm.  25 should probably be a design minimum, but I from what I've read, 20 can handle the load except in the most extreme conditions.

14ft 6ft 2ft
dia wt psi wt psi wt psi

.5 4.76 46 2.04 19.7 .68 6.57
.625 7.44 15 3.19 6.46 1.06 2.15
.75 10.71 6 4.59 2.6 1.53 .87
.875 14.58 2.8 6.25 1.2 2.08 .4
1 19.04 1.44 8.16 .62 2.72 .21
1.125 24.1 .8 10.33 .34 3.44 .11
1.25 29.75 .47 12.75 .2 4.25 .07

This data makes my proposed radiator placement a little more feasible.  Using a 7/8" tube I'd get less than 3psi backpressure and add 15lbs of water.  Using the EWP will save me about 8 of those, so I'm looking at adding about 7lbs and eliminating seperate intakes for cooling.