CASE STUDY

Requirement:

Design and develop an air supply and electrical power system to ultimately replace the AM32A-60 aviation support cart in military environments. The dash-60 provides “bleed air” for engine starting at up to 50 psi and 100 pound/minute flowrate, and is equipped with a 60 kW 400 Hz generator set for supplying ground power to aircraft. An additional piece of equipment – the AM32C-10 (dash-10) – relies on a functioning dash-60 for high pressure air supply to produce chilled, low pressure “conditioned air” at 50⁰F – 55⁰F for avionics cooling while on the ground.  A typical requirement is for ground power and conditioned air to be supplied concurrently, with bleed air reserved for engine starting purposes.

Current Status:

The dash-60 and dash-10 units number in the thousands and are deployed at numerous domestic and foreign military installations worldwide. Both these units have long been out of production; spares are in scarce supply creating support and sustainability challenges. This is an aging fleet in sore need of a more modern and sustainable approach.

Solution:

We concepted, designed, built and delivered a diesel engine-powered, multi-stage centrifugal compressor solution that has proven highly successful in testing and field demonstration. Included in the solution is a novel “bootstrap” turbo-compressor and heat exchanger module for providing conditioned air.

At the heart of the patented system is the ultra-efficient twin-stage intercooled centrifugal compressor “bleed-air” unit. This unit incorporates the integral high-speed transmission drive for compact, direct coupling to a 6.7-liter diesel engine. It also includes a direct-mount pad for supporting a 90kW permanent magnet, synchronous electrical machine for ground power.

The Voltaire bleed-air unit tips the scale at a mere 350 pounds; and with integral generator, 475 pounds. By comparison, a competing screw-type compressor air end sold into the jet engine start market (CD26) will weigh in at over 1650 pounds. Add to this the reduced efficiency of the twin screw unit, requiring a larger engine to drive it, and you have now incurred an additional 600-pound penalty… not attractive for mobile equipment.

The turbo-compressor module is tightly integrated so that full functionality may be incorporated into a single, compact support cart. In principle, this module operates similar to an aviation Air-Cycle Machine (ACM) which utilizes high pressure air in conjunction with a pair of heat exchangers, extracting energy via the radial in-flow turbine to deliver the needed chilled air at 3 – 5 psi. As both turbine and compressor stages are mounted to a common shaft, recovered energy is then absorbed by the compressor to produce the needed expansion ratio and ultimate cooling effect.

Total payload of the pneumatic, power, and conditioned air package is 625 pounds, and operates from a 1,000-pound 6.7 liter diesel engine. Moreover, and owing to the attained high efficiencies and general arrangement, the combined operational modes of ground power, conditioned air, and ECS/Bleed-air are now possible. In operational testing, the Voltaire system has demonstrated fuel savings of 7:1 over the incumbent dash-60. Noise profile is also significantly reduced affording enhanced operability in proximity of personnel and aircraft crews.

Starting with a clean sheet, Voltaire accomplished complete conception, design, build and delivery of the first operational system – on production tooling – 13 months after contract. Initial units to date have accumulated thousands of hours of run-time in testing and demonstration without incident. The Voltaire system continues to demonstrate robustness and performance not attained by other products.