Last month, the US Navy received a proposal for a second multiyear procurement (MYP II) contract for the production and delivery of V-22 Osprey tiltrotor aircraft. The five-year, fixed-price incentive proposal, submitted by the Bell Boeing V-22 Program—a strategic alliance between Bell Helicopter and Boeing Company—accounts for a total of 174 V-22 Osprey aircraft for the US Marines and Air Force Special Operations Command (AFSOC). The Osprey employs tiltrotor technology to combine the vertical performance of a helicopter with the speed and range of a fixed-wing aircraft. As advanced as it might seem, the V-22 Osprey (Fig. 1) may represent just a transition stage to a new aircraft being explored by Boeing based on pulse ejector thrust augmentor (PETA) technology.

Vertical takeoff and landing (VTOL) aircraft like V-22 Osprey (Fig. 2) are well-proven designs, with more than 145 Osprey aircraft currently in operation. PETA-based aircraft would also be able to make vertical landings and takeoffs owing to their many smaller pulse jet cells. Each cell is encased in a duct that augments the thrust with an increased amount of air, boosting the lift power of the aircraft. Each cell also is equipped with full directional controls, so that the aircraft can be precisely maneuvered during takeoff and landing. Once the ship is in the air, horizontal thrust engines take over. Such PETA-based thruster cells are said to have few moving parts for high reliability and ease of maintenance.

Of course, controlling all those cells poses a challenge for designers of electronic control systems, and undoubtedly calls for a large amount of parallel-processing power. The PETA pulse jet engine technology is actually a variation on a pulse detonation engine (PDE). A PDE employs detonation waves to combust a fuel/oxygen mixture. The engine operates in pulsed mode since the fuel mixture is injected into the combustion chamber between each detonation wave and fired by an ignition source. The design can achieve high thermodynamic efficiency and generates less heat and requires fewer parts than turbojet engines. But such designs, which have yet to be put into production, tend to be loud and suffer poor fuel consumption. By using a larger number of smaller engines, orchestrated under electronic control, that fuel consumption may be somewhat improved.

The change to many smaller engines brings embedded parallel computing into the fray. Electronics plays a part in most aircraft and engines but mechanics often play a more important role on the propulsion side. The switch to an array of smaller engines means more control points and more synchronization. There is also the potential for more optimization from a variety of standpoints, such as power, efficiency, and noise. All of these are critical to applications where helicopters and VTOLs currently operate. Highly efficient and silent would make an excellent VTOL. Unfortunately, PDEs are rather noisy at this juncture. Mechanical designs might improve on these points, but an electronic solution or augmentation would be more flexible.

Lessons for these advanced aircraft designs might be learned from the use of multicore processing solutions in current military vehicles. One such example is the 32-b system from Adapteva (see “Multicore Array Targets Embedded Applications” at electronicdesign.com). The Epiphany architecture has an array of 32-b microcontrollers connected by a high speed, two-dimensional (2D) mesh network.

Other multicore architectures like GPUs and Intel’s Many Integrated Core (MIC), codenamed Knights Corner (see “Get Ready For Some Hard Work With Multicore Programming,” on electronicdesign.com), are candidates for this type of engine control. Most microcontrollers designed for more conventional electric motor control typically handle one or two motors. These would be woefully inadequate for handling an array of PETA engines.

Replacing a large device with many smaller, individually controlled devices is not a new technique. It is being employed in other areas such as light-emitting-diode (LED) systems. Individually, an LED does not put out much light, but it is much more efficient than an incandescent bulb. The latter is being replaced either by one large compact fluorescent (CFL) bulb or an LED light that incorporates dozens—or even hundreds—of LEDs. While LED lights do not need array processors for control, they may include more than one micro. What this does is change the way designers think about the problem. LED lights do not have to be bulbs; they can be panels or almost any shape a designer can think of.

Multiple PETA engines fit a parallel design mold. They can scale in size and number, allowing different placement than a conventional engine in a VTOL might require. They could be very interesting for small UAVs or large aircraft. Boeing’s concept design looked more like a conventional aircraft with VTOL capability. In theory, this is possible because it employs an array of smaller engines.

What happens if one or more engines are damaged? Survivability is a critical aspect of the design. Rockwell Collins has demonstrated amazingly survivable UAVs (see “Rockwell Collins UAV Damage Tolerance,” on engineeringtv.com) employing computing technology that can scale to full-size aircraft. This type of support might actually be easier to include in multiple PETA engine design, but the computations are not going to be simple. It is likely this will be the mark for the design criteria, and conventional flight will render most of the computation array effectively idle.

Boeing, BAE Team On Directed Energy

Boeing’s Directed Energy Systems (DES) division has signed a teaming agreement with BAE Systems to develop the Mk 38 Mod 2 Tactical Laser System for the US Navy. Boeing serves as a subcontractor to BAE Systems under this contract. The tactical laser system couples a solid-state high-energy laser weapon module with the operational Mk 38 Machine Gun System. The addition of the laser weapon module brings high-precision accuracy against surface and air targets, such as small boats and unmanned aerial vehicles. The system also provides the ability to deliver different levels of laser energy, depending on the target and mission objectives. According to Michael Rinn, Boeing DES Vice President, “Boeing is committed to developing this directed energy system that will significantly enhance ship defense. Combining BAE’s engineering expertise with the proven directed-energy proficiency of Boeing’s DES division creates a team uniquely qualified to integrate directed-energy technology into the Navy’s shipboard armaments.” The two team members have worked together on this technology for more than two years, with Boeing DES performing a pair of field experiments in 2010 to demonstrate the accuracy of the system.