January 19, 2026
Description
This model contains components to assemble a fuselage frame section for an R/C aircraft. The bulkhead and corner pieces are designed to be self jigging during assembly (i.e. they should snap together and hold their alignment) but it is recommended to use glue such as CA at the joint surfaces.
These are the central frame components of a modular system that I call FD1 for constructing fuselages and other aerodynamic bodies. Additional components, such as nose and tail fairings, wing attachment structures, etc will be provided in separate models and linked. The figure below is an exploded view of components of this system.
These components use a 100 mm bulkhead width and height, which is the baseline 1U unit size in the FD1 system. The baseline unit length is 100 mm , but corner pieces are provided in a range of lengths corresponding to simple multiples of the baseline unit length. Additionally, they use a 3/16 inch panel thickness. Panels can be made from foam core, balsa, or any other suitable material, or covered in a film covering. Other unit sizes and panel thicknesses will be published as well.
All components were designed using python scripting and OpenSCAD modeling, allowing parametric design of many permutations of unit size and panel thickness. Additional information and source code will be linked here as they are published.
The 1U frame section uses 4 mm circular cross section longerons, typically using pultruded carbon tube or rod. Wall thickness of the longeron (if using tube) can be varied based on the strength needs of the specific application.
The outer perimeter, longeron holes, and fastener holes of the bulkhead cross section for the 1U unit size bulkheads conform to the dimensions shown in the diagram below:
This is an end bulkhead design option with holes for a 4 mm fastener inboard of the longerons.
This is an end bulkhead design option with holes for a heat press threaded insert for a 4 mm bolt inboard of the longerons.
This is an interconnect bulkhead that interfaces to corner components on either side, allowing extension of the structural module.
A flat section bulkhead that can be either glued to or sandwiched between end bulkheads. This bulkhead provides a mounting interface for a tail boom or other circular cross section structural component.
A flat section bulkhead that can be either glued to or sandwiched between end bulkheads. This bulkhead provides a mounting interface for a tail boom or other circular cross section structural component.
A flat section bulkhead that can be either glued to or sandwiched between end bulkheads. This bulkhead provides a mounting interface for dual tail booms or other circular cross section structural components.
4 corners per end bulkhead pair. The 1U length of the corners is 100 mm, but other multiples are provided to produce shorter or longer structural units.
The corners snap onto the longerons and onto the bulkhead longeron and corner interfaces (I call them greebles). I use medium CA on the mating surfaces during corner assembly but usually prefer to assemble the individual structural units without the longerons rather than assembling the full fuselage at once. When assembling a structural unit without the longerons is is important to keep the glue away from the interior surfaces of the greeble so that the longeron can still be inserted afterward. Be sure to check the fuselage unit is straight and the corners are properly snapped into place before the glue cures.
Detail of an assembled bulkhead, longeron, and corner piece
The greeble positive feature on a bulkhead
The greeble negative feature on a corner
A greeble test article printed at 4U scale
Greeble and corner assembly shown with a 4U design test article
Snapped into place
All components are designed to print in the orientation provided. Bulkheads are designed to print typically with 100% infill and multiple perimeters for strength. Corners are designed to accommodate printing in vase mode or 0% infill and without top and bottom layers, but could be printed with infill for greater strength. Printing with infill may make corner pieces difficult to snap onto the bulkhead's interface feature. If printed without a bottom layer, use a 5 to 10 mm exterior brim to help with first layer adhesion. I print the corners one at a time for higher strength and to eliminate stringing.
This collection is a set of models for R/C aircraft that I have designed to be generally interoperable and support design and fabrication of a wide range of aircraft configurations:
https://www.printables.com/@Uenbzsto/collections/2458682
These models are part of the FD1 fuselage structure system.
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License:
Creative Commons — Attribution
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