Fred, I can give you credit on that. But I do not think your creativity stay at where you were at 1992 or 0.09" to day in the year 2000. With your permission, lets consider this. Reconstruct your helical one turn with resistance wire of relative higher resistance. Use copper extension from the helical tips as current feeds. The copper will be in a form of sheet metal or fins. There are two function to the sheet metal, cooling and heading guide. The cooling is intended to keep slot from widening due to excessive heating. The guide is intended to do away the straight edge. The high/low resistance junction between wire/copper is intended to provide steep temperature gradient. Before start, make a straight span incision to the top where you want the conduit to be. Depth of cut is not critical, typically no deeper than the center of conduit. This will provide a "rail" for the sheet metals to keep track on conduit desired location. The lower trailing corner of the leading sheet metal guide is were the helical begins. The lower leading corner of the trailing sheet metal guide is were the helical ends. Find a way to bond the resistance wire to the sheet metal. The two sheet metals and the "rail" will align on the same plane. The two sheet metals will be suspended (mounted) on an insulator block or plexy glass if desire. There will be provision for the battery current to pass from first to second sheet metals reliably. The sheet metal to foam junction surfaces, if desired, can be thermally insulated with mica films. Oh, one thing worth mentioning, one turn helical loop(?) is structurally stronger than a plane loop at some what proportional to helical pitch size, in regard to this application. YK Chan ----- Original Message ----- From: FRED SAGE <[EMAIL PROTECTED]> To: YK Chan <[EMAIL PROTECTED]>; Scrollsander <[EMAIL PROTECTED]>; Soaring at Airage <[EMAIL PROTECTED]>; John and Sandra <[EMAIL PROTECTED]> Sent: Tuesday, October 24, 2000 10:47 PM Subject: Re: [RCSE] creating a wingrod tunnel in foam? YK; That's exactly how I've been cutting the slots for my carbon fiber tube spars since 1992. You can't get the remaining slot width down to the diameter of the wire (.023") because of wire burn. However, you can get it down to a very manageable width of only .090". Furthermore, as opposed to using a template at either end of the foam panel, you have the added advantage of extending the length of the tube slot to whatever is appropriate for the particular wing you're designing. A simple jig to cut 1/8", 3/8", 1/2", 9/16" and 5/8" and you've got all the bases covered from HLG to as big as you want to go. Fred RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
