Hi,

without getting into too may details of the model etc, I am attaching an image of a firewall doubler. The firewall was originally about 5mm thick and I added in birch ply doublers making it about 8 mm thick. The motor box is about 2mm larger on all sides over the size of the former and I have tristock all over the inside. I have fibreglassed also after taking the picture but not sure its come out that well. Now, the airplane is meant for 120 size glow but is coming to 4.2kg with the dle20. The 20 may not have 3D muscle and there are other associated setup issues (the throttle lever is on the other side as the servo, etc). The airplane will do with a 30- it has 1100sq.in of wing area and the wing loading with the 30 will be about 20oz/sqft or so. However, to install a dle 30, I have to recess the carb into the firewall. The white card template in the picture shows the size of the hole I need to make to recess the carb. My question is, is cutting this much off the firewall really advisable?

Note: the top of the motor box is on the left on the screen

Ameyam