I'm building a blown-up Ziroli but I'm using the same fix that worked on my smaller P-38's. I use the top hatch as a stressed member to carry some of the load from the rear booms. It is bolted to the firewall bulkhead and to the bulkhead aft of the wing opening this plus using spruce for the crutch rails stopped the cracking of the booms aft of the wing trailing edge. the plans don't say how to attach this hatch but making sure it is tied in properly is important.
Last edited by P38J; 07-01-2017 at 06:33 PM.