Take advantage of 3D software to make drawings
3D Studio Max & Gmax:
You might want to use this software by Discreet or its freeware version: Gmax. Both are quite the same idea though Gmax has export options towards games, while 3DSMax has export options towards video files and images renditions.
Either one you chose will help you make a 1:1 scaled build and enable you to "read" dimensions and angles from your screen.
Blender
Free and Open Source (under GPL). Doesn't dump hundreds of Megs on your harddisk as the program is pretty small compared the most others. http://blender3d.org/
primarily a modelling and game creation tool
since the sources were bought by the comunity for 100000EUR, the development became prolific, so features get added quicker now
has a built-in movie editor (allows you to put some of your 3D models in real life videos )
used by many FlightGear Modellers to create the 3D models for aircraft.
SketchUp is the coolest program if you just can get a grip of those standard CAD packages, with only 2D of in some cases orthographic views. With Sketchup you can intuitively sketch your cockpit project, and at the same time get drawings to build from with measurements.
From the website..
..anyone who loves sketching by hand but finds using CAD cumbersome or frustrating will appreciate SketchUp's unique approach: Instead of requiring users to learn a vast, complicated set of commands SketchUp combines a compact yet robust tool-set with an intelligent guidance system that streamlines the 3D drawing process. The result is an interface that supports a dynamic, creative exploration of 3D form, material and light without requiring large investments in training and support.;