Airframes for small unmanned aircraft could eventually be produced by three-dimensional printing - or more correcly "fused deposition modelling
" (FDM). This works by taking a computer-aided deisgn model, thinly slicing it and using this to drive a machine that builds up the part by laying down a polymer material in layers.
The US Air Force Research Laboratory's Manufacturing Technology program has produced the wing of a small UAV - Lockheed Martin's Stalker
- using FDM with the goal of demonstrating a lower-cost alternative to labor-intensive hand layup. If not perfect, the results were promising.FDM-optimized wing. (Photo: AFRL)
Under the Automated Disposable Airframe Production Technology (ADAPT) program, two wings were produced: one where the design was unchanged; and one where the inner and outer mold lines and mating features were optimized for the Ultem 9085 high-strength polymer used in Stratasys' FDM
Using Stratasys' Fortus portable production system the team was able to fabricate a full wing structure for around $8,000, substantially less than wings produced using conventional methods, says AFRL.
When proof-tested by Lockheed's Skunk Works to verify the structural models developed, the wing's downward deflection met predictions but upward deflection was more than expected. An effort to identify material and manufacturing process improvements for small UAV manufacture via FDM is now under way, says AFRL.