TECHNOLOGY AREA(S): Air Platform OBJECTIVE: Develop a non-contact transmission for helicopter applications that converts high speed engine outputs to high torque mast shafting which eliminates gear contacts within the transmission. DESCRIPTION: The Army utilizes a wide range of vehicles across ground and air platforms where mechanical transmissions are used to transmit power from the engine to the drive shaft. Gears are used to create a torque and speed conversion with mechanical contact between the gear teeth surfaces. Lubrication is necessary to create a protective film between rolling and sliding surfaces as well as provide sufficient cooling to prevent failure. As such, mechanical contact transmissions are vulnerable to loss of lubrication events and require regular maintenance for the lubrication system. The Army desires a solution to eliminate these gear, and potentially bearing, contacts within a transmission to reduce or even eliminate the dependence on lubrication. Non-mechanical contact gearboxes are of interest because of possible potential improvements in power density, wear resistance, noise reduction, and efficiency along with an inherent overload protection [1]. Simplification of the overall system with substantial weight savings is possible because the lubrication package would no longer be necessary. Eliminating the threat of loss of lubrication and minimizing wear allows the transmission life expectancy, robustness and survivability to increase greatly [2]. Recent efforts to develop non-contact gearboxes have focused on the magnetic planetary configuration. Magnetic planetary gearboxes transfer power within wind turbines, marine propulsion and hybrid electric systems [3]. Hybrid vehicles use this system in combination with a motor/generator to improve efficiency with a continuously variable transmission [4]. The use of magnetic gears is one example of an applicable non-contact transmission. In addition, new concepts for non-contact transmissions are highly encouraged. The Army is requesting innovative solutions for power transfer without the use of mechanical contact. Highly innovative game-changing power transfer concepts and configurations will be considered favorably. The concepts should aim to address the ability to accommodate multiple inputs and outputs at various connection angles. Configurations that are not able to accommodate the geometry needed for a helicopter transmission will also be considered, such as an automotive differential or co-axial configurations. Multi-speed capability is desired. At minimum, the gearbox concept should aim to give a torque and speed reduction typical of an Army scout helicopter. The typical speed reduction can be approximated with an input of 5,000 to 10,000 RPM and a main mast output corresponding to a 15:1 to 20:1 reduction at 500-800 hp. Concepts that lend themselves to future scaling up to the power class of a utility, attack or cargo class helicopter are desired [5]. Commercial applications of this technology span a wide range of helicopter and automotive drivetrains. This would include civilian rotorcraft, passenger vehicles, tractor trailers and construction vehicles with each application depending on scalability. The Army would like to apply the technology developed in non-contact transmissions to both block upgrades of current rotorcraft and potential new aircraft like the Joint Multi-role helicopter to reduce dependence on gear contacts. PHASE I: Investigate the underlying physical principals necessary to create a non-mechanical contact gearbox. Show conceptual configurations for the input and output to the gearbox. Determine the technical feasibility of multiple inputs and multiple outputs to better represent helicopter transmissions. Develop a preliminary gearbox design with an input of 5,000 to 10,000 RPM and a gear reduction ratio of 15:1 to 20:1 at 500-800 hp. Supporting calculations and modeling for design shall be included. PHASE II: Refine the design and calculations presented in Phase I. Determine the technical feasibility of scaling the gearbox concept to higher horsepower classes. Develop, test and demonstrate the technology on a component level and correlate with theory and calculations. Build a functional scaled prototype transmission for a proof of concept demonstration. Work toward a commercialization pathway with an industry partner. PHASE III DUAL USE APPLICATIONS: Design a full scale helicopter transmission. Develop, test and demonstrate the performance of a prototype transmission while working with industry. The intended end state is TRL 5 Component and/or breadboard validation in relevant environment. Collaboration with industry will produce opportunities to continue to develop non-mechanical contact transmissions for use in future Army helicopters. This technology would also be applicable to commercial helicopter platforms and could easily be applied to other ground vehicle and wind turbine gearboxes. REFERENCES: McGuinn, Jack. "Magnetic Gears: Sleeping Giant or Toothless Tiger?" Gear Technology Nov.-Dec. 2013: 36-39. Handschuh, Robert. Polly, Joseph. Gear Mesh Loss-of-Lubrication Experiments and Analytical Simulation NASA Glenn Research Center, Cleveland, Ohio. Nov. 2011 Frank, Nicolas W. Analysis of the Concentric Planetary Magnetic Gear. Diss. Texas A&M U, 2011. "Magnetic Continuously Variable Transmission." Magnetics Magazine. Magnetics Business & Technology, 04 Nov. 2013. Weden, Gilbert. Coy, John. Summary of Drive-Train Component Technology in Helicopters Technical Memorandum 83726. Lewis Research Center, Cleveland, Ohio. Oct. 1984 KEYWORDS: helicopter, rotorcraft, propulsion, transmission, drivetrain, gearbox, gears, gear, non-contact, non-mechanical contact, differential, automotive, magnetic, continuously variable transmission TPOC-1: Mark Riggs Phone: 410-278-9604 Email: mark.r.riggs.civ@mail.mil TPOC-2: kelsen laberge Phone: 216-433-2078 Email: kelsen.e.laberge.civ@mail.mil
