Mark Huber is an aviation industry veteran who has worked in the flight training, aircraft sales, aircraft component, and airport development businesses. He has flight time in more than 50 different and diverse aircraft, including helicopters, aerobatic aircraft, vintage warbirds, jet fighters, business jets and turboprops, and transport-category aircraft. He has jumped out of several of these—on purpose—with a parachute. His defense and aviation journalism has been published in a variety of national and international periodicals.

Contributor

Mark Huber

Aerospace researchers at the University of Texas at Austin and associated collaborators have received a five-year grant from the Pentagon and NASA to study the dynamic inflow of air associated with contra-rotating coaxial main rotor systems like that found on the Sikorsky S-97 Raider. Dynamic inflow refers to the control inputs to the rotor that affect the surrounding air, which in turn affects the forces generated by the rotor. The grant will fund the research and development of techniques that can measure dynamic inflow. The research team includes collaborators from the University of Maryland at College Park.

 


“It’s mostly an experimental project, where we’ll actually measure perturbations,” said University of Texas aerospace engineering associate professor Jayant Sirohi. “It’s one of the few times it’s been done for any rotor system and we’ll be doing it for the first time on this special rotor system.” Last year Sirohi and his team began wind-tunnel testing the coaxial rotor design to accumulate performance data.

 


That data showed that the coaxial system they developed had a lift-to-drag ratio that was 1.5 times greater than that of a single-rotor helicopter. Sirohi said that the gains could potentially be even greater with rotor blades finely tuned to improve lift.

 


Sirohi points to the inherent advantages a coaxial system has over traditional single-stack rotors; stacked rotors turning in opposite directions boost the helicopter’s speed and efficiency by canceling out forces that cause uneven lift on single-rotor helicopters. “You don’t have to get rid of the extra lift on the advancing side of the rotor, because the two rotors cancel their rolling moments,” Sirohi said. “So the aircraft remains in level flight, and because you can make more efficient use of the rotor disk, forward flight is more efficient,” he said.

 


Graduate students on Sirohi’s research team are building the 20-percent-scale rotor system and much of the research is necessarily focused on adapting devices and measuring techniques to the small scale. “We’re doing everything on a model scale, so it gets difficult to fit everything in that small volume. And we’re also spinning much faster than a full-scale helicopter rotor,” Sirohi said. In addition to developing experimental tools, the team is working on fine-tuning the rotor system controls, so that variables such as pitch can be carefully adjusted. Once the measurements are collected, they will be used to make a digital model of the system scaled up to actual size. But Sirohi said it’s likely that the data-collection methods could influence other research beyond helicopters. “The measurements will be used to make a full analytical model of this system, but more important we’ll be developing some tools along the way. Some experimental techniques, some analytical tools that we may be able to use in other types of research, not restricted to helicopters,” he said.

 


Sirohi acknowledged that both Sikorsky and AVX are focused on developing helicopters with contra-rotating main rotor systems as part of the Defense Department’s ongoing competition for the Future Vertical Lift program, but much of their work is classified and product-specific, while his team is more focused on the basic science. “While these [industry] teams are more interested in getting a prototype flying, we are looking at the fundamental physics of these systems,” Sirohi said.

News and issues regarding all manner of civil and military rotorcraft and their powerplants, including helicopters, tilt rotors and unmanned air vehicles.

Texas Researchers Study Coaxial Inflow

Such a system could provide significant gains in a helicopter's lift-to-drag ratio.

2024 Corporate Aviation Leadership Summit

Charlotte Bailey

News about bills, laws, regulations and other governmental decisions affecting aviation and aerospace. Topics include FAA re-authorizations, taxes on fuel and aviation activities, environmental legislation, ICAO decisions, governmental mediation of labor conflicts and World Trade Organization disputes and decisions.

Essential news and analysis on the defense aerospace business. Your trusted source for new and ongoing programs and requirements in military aircraft (manned and unmanned), engines, avionics, weapons and associated systems, including ground-based air defense.

Pentagon permission facilitates sale of Bell 412EXP and 407M

U.S. Approves $800M Bell 407/412 Sale to Iraq Military

News and information on safety procedures and concerns.

News and issues relating to the aerospace industry that are related to the science, engineering and business of flight in space involving civil, industrial and military applications, and similar topics related to flight in the atmosphere of the Earth that are not covered more directly by other AINonline subject channels. In other words, both astronautical and aeronautical subjects, except for those aeronautical topics that are specifically covered elsewhere on this website.

Fire and disaster management agency to use aircraft in aerial reconnaissance role

Japan Orders Its First H160 for Emergency Response

Flights with two scaled technology demonstrators will inform potential future iterations 

Singaporean eVTOL Conducts Test Campaign In Germany 

Matt Thurber

New developments and products in avionics, specifically about aircraft electronics in the cockpit.

News and issues relating to business, corporate and private aviation, primarily regarding turbine-engine-powered airplanes and helicopters. Subjects include aircraft, engines, maintenance, operations, personnel, acquisitions, accidents, safety, security, and training.

More In Rotorcraft

U.S. Approves $800M Bell 407/412 Sale to Iraq Military

Pentagon permission facilitates sale of Bell 412EXP and 407M

Japan Orders Its First H160 for Emergency Response

Fire and disaster management agency to use aircraft in aerial reconnaissance role

Singaporean eVTOL Conducts Test Campaign In Germany

Flights with two scaled technology demonstrators will inform potential future iterations

FAA Approves TSO for ASU Panoramic Night-vision Goggles

Lightweight white-phosphor NVG have a 94-degree field of view

FAA Floats Special Conditions for Skyryse Fly-by-wire R66

Proposed rule addresses pilot awareness of control limits

Vertical Lift Groups Extend Trade Show Partnership

European Helicopter Association and Vertical Aviation International extended their alliance

Sikorsky Is Upgrading the Black Hawk Helicopter for Evolving Military Needs

Armed forces will be able to outfit Black Hawks with new armament and equipment.

Sikorsky’s S-97 Raider Points to a New Level of Performance for Future Helicopters

Originally developed for the U.S. military, X2 technology is in search of a new customer.

AIN Products

SUBSCRIPTIONS

RESOURCES

ABOUT AIN