Step 1: Building the Turtleback Form (Jig)
If you’ve sat or flown in a Cozy IV, you know that the canopy glass comes really close to the side of your head! So I knew from the outset that I wanted a wider and higher turtleback and canopy. So I built my turtleback to be 1 inch higher and 2 inches wider at the forward end than the plans dimensions. Alot of builders are raising the turtleback to get extra headroom and actually improve the cosmetic lines to the cowls. (Addendum: After the turtleback was built, I eventually added a wedge of foam to raise the front of the turtleback by an additional 3/4 inches (1.75 inches total) to try and get rid of the canopy glass depression.)
It's fairly easy to raise and widen the canopy by just resizing some of the jig frames. I didn't make any modifications to the aft end, therefore it conforms to the firewall as per plans. I also incorporated two additional lattice strips into the jig to better support and contour the foam strips. Naturally, I assembled the jig with drywall screws.
A Note about Prefabricated Turtlebacks
If you are sticking with the plans-built dimensions, then you should really consider buying a prefabricated turtleback. The purchase price more than offsets the work required to build the jig, form the foam strips, fair, fill, and sand. Featherlite makes a nice, nomex-cored T-back, but you’ll need to plan ahead as there is usually a large lead time. AeroCad also makes a nice "SB" pre-fab turtleback that is approved by Co-Z Development.