First Carbon Fiber Tandem-Duct Airframe Ready for Integration

April 24, 2019

Los Angeles, CA April 24, 2019 – The first pre-production carbon fiber airframe for a tandem-duct vehicle has been completed by Aerofex and Sub-g Composites. The airframe includes integral carbon fiber ducts, which play a key role carrying flight and ground loads. The use of carbon fiber was crucial to reducing the vehicle’s weight. It also presented the opportunity to take-on some long-vexing manufacturing challenges.

The platform’s beams, ducts, fan blades, and control surfaces, are all hollow structures with outer molded surfaces. Their internal volumes house the vehicle’s actuators, sensors, and harnesses. Fabricating these types of components at this scale using conventional methods requires expensive molds, particularly for the ducts.

“Considering the efficiency and safety of ducted fans, we think more developers will use them instead of exposed rotors as their cost and weight drops” explains Mark De Roche CTO at Aerofex. “Our approach permits resizing the diameter of the duct and fans for each application, without prohibitive tooling costs.” The technique is particularly well suited to counter-rotating applications where matching sets of fans are required, according to De Roche.

The ducts on Aerofex platforms also provide flight control, so the incentive was high to find a cost-effective method of producing them. The solution employs braided carbon fiber preforms and a resin transfer molding process in low-cost aluminum molds. Braiding is one of the oldest textile weaving processes and yields composite parts that are stronger, stiffer, and tougher than conventional layups – and are lightweight. The 3 meter airframe weighs just 11 kg including the ducts.

Aerofex will complete the integration and test of the vehicle’s propulsion and control systems prior to transferring the platform to its customer. Aerofex is a Los Angeles based aero-tech development firm working to increase the utility of flight. Sub-G Composites is a manufacturing subsidiary of Aerofex Corp.