Over the last 100 years of powered flight, the performance of aircraft has almost universally been constrained by the performance of the available propulsion systems. The imagination and ambition of aircraft designers has always been tempered by the low thrust-to-weight ratio, large size and poor fuel consumption of available propulsion systems. The introduction of the turbofan has completely transformed large scale aviation by providing an engine with improved thrust-to-weight ratio, low fuel consumption and excellent reliability. However, small and light weight aircraft are still restricted by their use of low performance reciprocating engines. The Propulsion Systems group at MDC is developing innovative and cost effective propulsion technologies that will make the higher thrust-to-weight ratio, low noise, low fuel consumption and reliable turbofan engine available to designers and operators of light aircraft.
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Multi-Disciplinary Systems
Propulsion Systems
Over the last 100 years of powered flight, the performance of aircraft has almost universally been constrained by the performance of the available propulsion systems. The imagination and ambition of aircraft designers has always been tempered by the low thrust-to-weight ratio, large size and poor fuel consumption of available propulsion systems. The introduction of the turbofan has completely transformed large scale aviation by providing an engine with improved thrust-to-weight ratio, low fuel consumption and excellent reliability. However, small and light weight aircraft are still restricted by their use of low performance reciprocating engines. The Propulsion Systems group at MDC is developing innovative and cost effective propulsion technologies that will make the higher thrust-to-weight ratio, low noise, low fuel consumption and reliable turbofan engine available to designers and operators of light aircraft.
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Micro-Turbofan™
The core propulsion technology being developed by MDC is the Micro-Turbofan™. The fundamental difference between the Micro-Turbofan™ and a conventional turbofan is that the power-turbine driving the by-pass flow is located in front of the combustor rather than at the engine exhaust. In its standard configuration, the Micro-Turbofan™ is ideally suited to engines producing less than 1,000 lb thrust and extending down to below 100 lb thrust. A Micro-Turboshaft™ configuration is also available, with shaft power outputs of less than 1,000 hp. Fuel consumption for both configurations is comparable to conventional small turbofans and turboshafts, but with improved thrust-to-weight and power-to-weight ratios. The Micro-Turboshaft™ engine is ideally suited to light-sports aircraft and low-speed UAVs, while the Micro-Turbofan™ engine will allow higher performance for UAVs and commercial light aircraft. Additional advantages are increased payload, reduced exhaust temperature, greater fuel flexibility, longer service interval and a simplified installation process.
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Micro-Turboalternator™
The micro-turboaltenator uses the same core turbomachinery as the micro-turbofan, but instead of driving a fan to provide thrust, drives a light weight, permanent magnet generator developed by a 3rd party collaborator to provide electrical output. Using a compact recuperator to recover heat from the exhaust decreases the fuel consumption to 1 lb/hr/kW, while still maintaining a power-to-weight ratio of 1.7 kW/lb. This is six times the specific power, or 12-15 times the energy density, of lithium polymer batteries. Electrical output ranges from under 10 kW to over 100 kW. The micro-turboaltenator is ideally suited to the next generation of hybrid light-sports aircraft and UAVs, as well as hybrid road vehicles and stationary power generation.
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Distributed Lift
The Distributed Propulsion concept is enabled by small, low thrust engines, such as the Micro-Turbofan™ and a compact liftfan. Contemporary small aircraft are typically limited to using one or two large engines, because there are currently no small engines with a suitable performance. Control is primarily provided by moving the aerodynamic surfaces, either flaps on fixed wing aircraft or rotor blades on helicopters. However, if the total thrust requirements of an aircraft can be met with a large number of small engines then differential throttle control can be used to control the aircraft. This approach has a number of benefits that are particularly suitable for low-speed aircraft operating in restricted environments; eliminating movable control surfaces and actuators greatly simplifies the construction of the airframe; multiple engines provide redundancy in the event of damage or failure; control via thrust is independent of speed and acts more directly.
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Ice Protection Systems
Under Navy funding, MDC has been working to develop an integrated system capable of reliable ice-detection, de-icing and anti-icing, in addition to structural diagnostics for fixed-wing leading-edges and rotorcraft blades. The basis for this system is structured Carbon Nanotube (CNT) enhancements that can either be embedded within the composite laminates during manufacturing, or applied as a separate surface layer in a secondary process. The aligned CNTs are sufficiently long (20-30 um) to span interply matrix regions, improving electrical conductivity by a factor of a million and thermal conductivity by orders of magnitude. Overall, this system offers many benefits over current Ice Protection Systems (IPS), allowing conformal, uniform, and structurally integral heating and sensing elements, and enabling closed-loop operation, all of which contribute to a reliable, robust and durable system design. Compared to the conventional resistive heating blanket approach for de-icing, the CNT-enhanced system is more efficient, lighter weight, lower profile, and provides integral damage detection feedback.
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Electro-Mechanical Design
In parallel with internal programs developing propulsion and ice-protection systems, MDC has been providing outsourced technical consulting services for electro-mechanical design for nearly a decade. Much of this derives from the expertise of MDC engineers in specific niche competencies, such as piezoelectric transducers, shape memory alloys, ultrasonic methods, energy-harvesting and power-transfer techniques, pattern and image recognition; composite, hybrid and nano-engineered materials; and general non-linear multi-physics simulation and modeling. MDC has extensive experience in the design, simulation, fabrication and evaluation of these types of complex electro-mechanical systems. The focus of this consulting service has been elevating the technical maturity of customer concepts by validating fundamental aspects through proof-of-concept experiments and embodying client innovations in prototype demonstration units. Through a trusted network of vendors and partner companies, MDC can facilitate the fabrication, assembly and testing of nearly any type of device in any conceivable range of conditions, including consumer, military and space environments.
