Thread: Build Log Mike's P-47D Thunderbolt 48"
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Old Jan 17, 2009, 12:01 PM
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Mike Brinker
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SouthEast Michigan
Joined May 2008
557 Posts
Hotwire Time (Cutting the Foam)

The Thunderbolt is my favorite WWII fighter. If this project works out (which I hope it will), I may be making another. Based on my piloting skills, I may be making another anyway! Honestly, If I crash, and it isn't to serious, I could simply use the templates I have to repair the damaged areas. Maybe this is wishful thinking on my part......

I have read many projects here in the scale area and some of the techniques used were not completely explained. I am sure this is because I have not built a plane from plans like this. I have not worked with foam (other than repairing my foam ARF planes. So, I figured that I would take the extra time to explain what some of the techniques are that will be used for this project. I will try and explain them as used during the building of this p-47.

The Foam
There is a lot of cutting to do. Just the main fuselage has 17 sections for each fuselage half. So, 34 parts to form the fuselage not including the stabilizer or elevator sections of the tail.

My P-47 will be using "pink" foam that is commonly used to insulate walls. Home Depot sells foam sheathing F150 Board 2 In. x 48 In. x 96 In. Model 270895. Is cost about $30 per sheet, but you could easily make two or more planes with this amount of foam.

Foam Cutting With A Hotwire
Trying to cut foam with a blade or saw is possible, but will be time consuming and messy. The hotwire technique makes for quick and clean process. The quality of the cut ( with practice ) is remarkable. A hotwire cutter is basically a wood handled tool with a wire stretched out like a cheese cutter or bow & arrow type shape. The wire is attached to a power source and the power is regulated with a transformer and dimmer dial so you can control the temperature of the wire. Yep, the electricity heats up the wire enough that you can slide the wire along the template and cut through the foam like a hot knife through butter. Here is a link to a great article on how to make your own hotwire device for around $30. Make Your Own Hotwire

Be sure to keep in mind that the design of your cutting tool should allow foam blocks to be manipulated around the wire. If the frame of the hotwire tool is to close to the wire, it might be difficult to move the foam around as you cut. The hotwire I used was placed in a vice so I could cut the foam as if I was standing at a large jigsaw table.

First Cut
I have 15 different templates labeled "A" through "N". I have 2 "E" templates. The nose section starts with template "A" and "B". I pin "A" to one side of the foam and "B" to the other. If these are laid out properly, you should be able to make a left side of the fuselage, then re-position the template 180 degrees and cut a right side of the fuselage. See the picture below:
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Last edited by tr6world; May 12, 2011 at 08:47 PM.
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