Browse Topic: On-board energy sources
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This SAE Information Report contains definitions for hydrogen fuel cell powered vehicle terminology. It is intended that this document be a resource for those writing other hydrogen fuel cell vehicle documents, specifically, Standards or Recommended Practices.
Composite materials have become widely adopted in commercial aviation, as aerospace manufacturers look to use them to drive weight reduction and improved fuel efficiency in new aircraft designs. In the case of aircraft rotary blades, the poor wear properties of these materials have necessitated the development of metal leading edge guards that can provide critical protection against erosion and impact damage during flight. Electroforming has been a leading process for the manufacture of these protective guards, with nickel parts providing excellent wear resistance that significantly extends the service life of the rotary blade assembly. Currently there has not been a focus on utilizing direct electrodeposition of metal on to carbon filled epoxy composite structures, as traditional plating-on-plastics approaches require considerable effort in surface preparation and normally do not provide adequate adhesion to the underlying structure. Alpha Metalcraft Group has been working in cooperation with aerospace suppliers in the design of an electroplating ready composite structure that would allow for direct nickel deposition, provide excellent adhesion, and significantly reduce both the time and cost for the manufacture of ready-to-assembly rotary blade structures. Test panels were constructed of commercially available prepreg materials or by resin infusion of dry fabrics that incorporated different metal containing conductive layers to allow for the direct deposition through a nickel sulfamate electrodeposition process. Different surface modification strategies were investigated to expose the metal conducting layer and thereby provide the metal-to-metal bonding surfaces required for successful electrodeposition.
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The purpose of the NATO Next Generation Rotorcraft Capability (NGRC) Support Partnership funded Novel Powerplant concept study was to identify, analyze, and compare novel powerplant concepts that could fulfill the NGRC need in a solution-agnostic approach. The outcome of the study provided NSPA and the NGRC participating nations with increased knowledge and understanding of the powerplant domain to inform assessment of future NGRC platforms. This study modeled four aircraft configurations to derive propulsion sizing requirements and compared propulsion configurations for each. The propulsion system configurations considered included three levels of conventional gas turbine technology (In-service GT, 2025 GT, and 2035 GT), hybrid electric (battery), hybrid hydrogen fuel cell, and hydrogen combustion. The results of the study considered both quantitative and qualitative evaluations. The quantitative analysis determined aircraft and propulsion system sizing to align with the expected NGRC need at different max cruise speeds, and compared performance along with recurring, non-recurring, and operational costs for each. The qualitative analysis investigated the impacts of wider technical, capability, and supportability considerations for each propulsion concept. Assuming a notional NGRC entry into service target date of 2035, this study shows that, when considering both quantitative analysis and a qualitative review, a modern gas turbine is the most reasonable solution space to deliver the performance and multi-mission capability expected.
Helicopters' Vertical Take-Off and Landing (VTOL) capabilities are essential for maritime operations, especially for small-deck naval vessels. Unmanned Aerial Vehicles (UAVs) offer a cheaper, expendable, and efficient alternative for certain tasks, such as reducing pilot risk and lowering fuel consumption. While the procedures to approach and land on (moving) ships are standardized and bound to established operational limits in the case of crewed helicopters, UAVs lack such guidelines. This study investigates optimal rotary-wing UAV approach trajectories to a moving ship, for varying wind conditions and relative initial positions, and for different objectives. The goal is to provide preliminary guidelines for maritime UAV recovery operations, and a preliminary estimation of performance-based operational limits. The optimal trajectories are obtained using a global path-performance optimization framework based on Optimal Control Theory. The trajectories are compared to each other and to reference cases using the Longest Common SubSequence (LCSS) similarity measure, revealing how the unmanned helicopter adjusts its path to exploit the wind direction and profile for more efficient ground speeds. The violation of performance and/or geometric constraints is used to preliminarily indicate the presence of operational boundaries. The control effort and energy consumption are used to identify optimal starting positions for the helicopter approach phase for a given wind profile and intensity.
This paper presents experimental research aimed at developing novel low lubrication methods for rotorcraft and jet engines, focusing on sustaining minimal lubrication to prevent catastrophic bearing failure during loss of lubrication (LoL) events or to increase fuel consumption performance on once-through, fuel-oil bearing lubrication engines. Utilizing two high-speed bearing test rigs simulating low and high thrust class engine conditions, the study establishes lower bounds for oil flow rates necessary to maintain thermal stability and prevent thermal runaway in hybrid ball bearings. These findings inform the design of the Zulu Pod (ZPod), a passively driven, self-contained oil delivery system that uses engine compressor bleed air to precisely meter lubricant flow. Engine test stand results demonstrate that replacing traditional fuel-oil lubrication with the ZPod system reduces thrust specific fuel consumption (TSFC) by an average of 7%, with up to 11% savings, without compromising engine thrust or bearing health. The ZPod offers a simplified, efficient alternative to fuel-lubricated systems by eliminating fuel diversion for lubrication, enhancing fuel efficiency, and maintaining bearing performance in attritable or single-use engines. Additionally, the study highlights the potential of minimal lubrication supplied by the ZPod to extend operational life during LoL scenarios, enabling safer aircraft recovery. Future work will focus on extending testing to higher thrust classes and optimizing ZPod designs for broader applications.
ABSTRACT The US Army is seeking improvements in the fuel efficiency of their military vehicles.. They have initiated a number of R&D projects aimed at advancing the state-of-the-art of powertrain efficiency including demonstration in a laboratory environment. This effort will set a benchmark for the vehicle integrators, allowing them to improve future vehicle offerings. The SAIC, AVL, Badenoch, QinetiQ and Ker-Train Research team offered powertrain solutions from 7 Tons to 40 Tons that achieved the goal of 44% thermal efficiency and the stringent flexible fuel and emissions requirements. In each of these offerings the team was able to identify modifications to existing engines that allowed dramatic improvements in the thermal efficiency. These efficiency improvements were achieved through a combination of techniques, combustion cycle adjustments using in-cylinder pressure monitoring and precise control of fuel injector timing, and turbo-compounding. For the R&D project, the fuel injector timing will be controlled using commercial engine development hardware and software. The high speed hardware emulates the engine control module but allows the developer to finely tune the fuel injection to maximize the 50% Maximum Fuel Burn point (MFB50) with only limited NOx production. This will be accomplished using a variety of fuels and maintaining the output power to within 2% of the engine’s nominal rating. This paper will describe the fundamental diesel combustion process that must be controlled and techniques for usable power extraction from the waste exhaust gases to provide this performance. It will describe the engine development tools that enable these controls changes to be realized within a vehicle development cycle and retain the baseline engine maturity.
Thermoplastic composites are serious competitor for classic epoxy composites. They have comparable properties to epoxy composites, but characterize much lower processing costs. There are several methods of manufacturing the components from thermoplastic composites. One of the most interesting method in terms of efficiency is thermoforming on a press. This technology allows to product of the aircraft parts such as: ribs, brackets, covers, stiffeners. Thermoplastic composites are resistant to most solvents such as grease, oil and aviation fuel. They are also non-flammable and heat-resistant. This all makes them suitable for use in aircraft as upholstery, casing or elements around the tank. PZL Mielec has been developing press thermoforming technologies since 2016 and is the owner of the several patents in this area.
In this paper, a comprehensive dynamic simulation of a parallel hybrid gas-electric single main rotor helicopter involving a motor/generator (MG) pair and a differential planetary gear transmission (PGT) arrangement forming an electronic continuously variable transmission (E-CVT) was performed. This notional hybrid electric helicopter was sized based on a retrofit of a dual engine, 10000 lb, 2500 Hp class helicopter. The total weight added by the electric components was 182 lbs which increased the propulsion system weight from 1184 to 1366 lbs. The simulation results found that at 110 kts cruise, the hybrid electric system enabled a 27% reduction in main rotor rpm which resulted in an 18% reduction in the fuel burn rate. It is concluded that use of an E-CVT parallel hybrid propulsion system offers potential for increased flight range and reduced fuel consumption in medium to large-scale helicopter applications.
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