Frame11

Well over the xmas break and so back on deck with musings on drawing lines on a computer.Frame11 is probably the most well known of the spitfire frames as it is the main hoop behind the Spitfire pilot.Also it mounts the pilots seat off it and carries the armour plate to protect him/her.The structure is a double frame,the last in the cockpit section and is joined by butt straps,the lower ones also carry the mounting holes for the frames diagonal braces.There are no internal spacers but a reinforcing channel does come down from the frames shoulders internally.This evolved throught the spitfire timeline as more powerful engines came available which nescitated reinforcing.At the datums are butterfly gussets to tie the datum brace and the diagonal braces together.This datum brace held the mountings for the seat mount and armour plate.Just under the shoulders are the cutouts for the canopy rail on each side.The inside of the frame holds an internal C coaming channel and also the top shoulders.On the back of the frame is the mounting plate for the Spitfires Voltage regulator which is held on by 4 bolts.On the front is the pilots head armour plate.On the rear bottom of the frame is brackets and gussets for the elevator bellcrank assembly.Front face of the frame are various angle stiffeners and on the back begin the intecostal brackets for the rear fuselage shape.

The frame changed shape from the MkIX to MkVIII with the internal curve being different.This was to give added  material and strength under the frames shoulders.The inernal channel going from the short shaped piece to the long internal C channel that ties in with the inside C Coaming channel.Here are some pics..