[Adrian Clark]

Is there a purpose to front gap other than copying it from 1114's chassis? If you took out the front gap and made it like you did in the back minus the cutout in the flange you'd have a pretty solid frame.

Side note: because of your cim cutouts in the bellypan and the flanges on your frame it will be impossible to either install or remove the gearboxes once the frame is assembled. I suggest elongating the slot for the cim to allow space for the gearbox to slide out from under the flange. Details like this are often missed in cad, make sure you put some thought in how this thing will be built and assembled.

edit: EricH is right, triangles are your friend, quoted for truth.