Nascent supersonic business jet maker Aerion has not given up its effort to find an airframer to build its eight- to 12-seat Mach 1.6 twinjet, but meanwhile the Reno-based company plans to earn revenue while at the same time helping the subsonic sector to fly more efficiently.
Through its new business unit, Aerion Technologies, the company is able to reuse the natural laminar flow (NLF) expertise it developed to allow the Aerion business jet to fly efficiently at both subsonic and supersonic speeds. Airflow typically starts as laminar, or smooth, flow across an aerofoil or surface before it transitions to turbulent flow, which increases skin friction drag by 90%. But determining the position of that boundary and designing for maximum NLF is not trivial.
"In parallel with discussions to find an airframer to build the Aerion [supersonic business jet], we found there was latent demand on what can be accomplished with NLF on subsonic aircraft," said Doug Nichols, Aerion chief financial officer. "We're under contract now with several OEMs to look at how NLF could help with new designs."
Aerion Technologies' software suite includes tools for rapid computation of the location of the transition between laminar and turbulent flow. "You can do a complete aircraft in an hour," said Richard Tracy, Aerion chief technology officer and developer of the NLF intellectual property. "Tools were painfully slow in the past. It could take weeks in the hands of a very knowledgeable team to estimate the location of the transition between laminar and turbulent flow for one flight condition."
An aircraft designed with NLF in mind from the outset will look different than most of today's aircraft. "High degrees of wing sweep limits the amount of NLF that can be achieved," said Tracy. "An optimised NLF design will tend to drive you to a lesser sweep and thinner wing." The payoff is a significant drop in drag, hence fuel burn. "With NLF, you can get double-digit reductions in drag," said Tracy.
Tracy said Cessna was most likely the earliest adopter of NLF in business aviation with its CJ series of jets. Piaggio also used the practice with its Avanti turboprops for "significant" performance gains, said Tracy. Most recently, he said, Honda is "aggressively trying to employ" NLF on the HondaJet and Dassault has been researching NLF on horizontal stabilisers.