Aerion is preparing to start another round of test flights in the development of what would be the world’s first supersonic business jet. A new test article is set to fly in the centerline position beneath one of NASA’s F-15Bs either this month or next. The new section of aerostructure, which is a bi-convex airfoil specimen called a “strongback” with a 40-inch vertical span and an 80-inch chord, has been built to incorporate findings from the last round of flight trials, held in the summer of 2010. These reached speeds of Mach 2.0 and used an instrumented flat plate to map the high-speed flow field under the F-15B and validate computer modeling by Aerion’s engineering team. Instrumentation on the test article is primarily an infrared camera, according to Aerion test manager Jason Matisheck. “Due to the different heat transfer rates between laminar and turbulent boundary layers, we get a video of the boundary layer state of the entire test article as the aircraft does its run. There will be four temperature sensors embedded in the paint of the test article to calibrate the infrared image. The strongback has several five-hole pitot probes that measure flow angularity, and freestream conditions will be measured by the aircraft nose boom.”
According to Aerion, the new test article will be more representative of the Aerion wing to evaluate supersonicboundary-layertransition properties. This will prepare the way for establishing manufacturing standards for surface quality and assembly tolerances. The flight trials will test the airfoil for waviness and surface smoothness with a view to maintaining laminar flow. “There has not yet been any focus in the civil [aerospace] regime in transonic and supersonic speeds up to about Mach 2.0,” explained Aerion COO Doug Nichols. “We will be looking at allowable tolerances to ensure laminar flow from the perspective of manufacturing and operations, by looking at the allowable roughness. We think there is a fair amount of tolerance.”
Aerion contemplates a six-year development program, once an OEM partner has committed to funding and supporting full-scale development of the supersonic business jet. Nichols acknowledged that Aerion has had discussions with prospective OEM partners from outside the industry’s existing main players, such as aircraft manufacturers from new markets like Russia and Asia. He indicated that one of these companies might end up as part of the eventual joint-venture partnership with a main OEM. Once launched, the supersonic business jet may well take a brand name designated by Aerion’s main partner.