US AFRL plans to improve aircraft engine inlet duct fabrication

6 April 2020 (Last Updated April 6th, 2020 10:37)

The Air Force Research Laboratory (AFRL) in the US has announced that it is working on a programme that seeks to introduce new processes for the fabrication of aircraft engine inlet ducts.

US AFRL plans to improve aircraft engine inlet duct fabrication
The Kratos XQ-58 Valkyrie is an experimental stealthy unmanned combat aerial vehicle, designed under the USAF Research Laboratory’s Low Cost Attritable Aircraft Technology project portfolio. Credit: US Air Force.

The Air Force Research Laboratory (AFRL) in the US has announced that it is working on a programme that seeks to introduce new processes for the fabrication of aircraft engine inlet ducts.

The aircraft engine inlet ducts offer continuous air supply to the engine compressor and maintain its efficiency.

The usual fabrication process for the inlet duct comprises composite material pre-impregnated with a synthetic resin to a multi-piece steel mandrel. The mandrel is placed in an autoclave, a heated pressure vessel, for processing.

Under the initiative, the Manufacturing and Industrial Technologies Division of AFRL has collaborated with a contractor team to identify the benefits of replacing this legacy manufacturing process.

The new method involves replacing the hand-applied composite prepreg with an automated overbraid process.

A lightweight single-piece shape-memory polymer mandrel will also be used over the steel mandrel.

The contractor team comprises Cornerstone Research Group, A&P Technology and Spintech.

AFRL Manufacturing and Industrial Technologies Division’s Low-Cost Attritable Aircraft Technology Initiative manufacturing lead Craig Neslen said: “We believe that the introduction of a reusable shape memory polymer mandrel together with the automated overbraid process and an oven based VARTM composite cure will lead to significant cost and cycle-time reductions.

“Quantifying the manufacturing benefits and validating structural integrity will be critical to establishing a positive business case and convincing designers and manufacturers that the new materials and processes should be incorporated into future low-cost engine inlet duct designs.”

The team has already completed element analysis finalisation of the overbraid architecture, manufacturing a shape memory polymer forming tool and the SMP mandrel.

The initiative will fabricate a total of four inlet ducts, following which, production time and associated costs will be compared to the legacy design.

Subsequently, AFRL will deliver the final inlet duct to the government for further integration into the Aerospace Systems Directorate’s complementary airframe design and manufacturing programme.