Raytheon Aircraft's new Hawker Horizon "super mid-size" business jet, to be unveiled at the National Business Aircraft Association show on 19 November, is the launch application for Honeywell's Primus Epic integrated avionics. Honeywell will be a risk-sharing partner in the programme, integrating equipment from other vendors and supplying a complete system to Raytheon for installation the aircraft.

The Primus Epic blends the aircraft-wide network capabilities of the existing Primus 2000 avionics system for corporate and regional aircraft with the cabinet-based modular architecture of the company's Boeing 777 avionics. The Virtual Backplane Network, as Honeywell calls this concept, allows functional modules to be located anywhere in the aircraft and connected by a high-speed databus.

These field-removable modules are the building blocks of the Primus Epic. Modules for computing, database storage, input/output, network communication, and power supply are plugged into a hardware cabinet called the modular avionics unit (MAU). Primus Epic applications will typically require between one and four MAUs, each with four to 24 module slots, connected by the latest version of Honeywell's ASCB databus which provides a throughput capacity of 20 megabits/s.

Honeywell has developed its own software operating-system for the MAUs and "smart" liquid-crystal displays. The Digital Engine Operating System provides standard interfaces and services for all the resident functions, and allows one function to be changed without affecting others. Software for multiple critical, essential and non-essential functions can be run on the same processor.

The MAUs can be configured to perform many avionics functions within one box, including autoflight system, fault-warning computer, flight-management system, aircraft utility-systems control and another new feature, the integrated sensor suite. This is a complete primary-sensor system consisting of global-positioning and air-data modules, and a small inertial-measurement unit combining ring-laser and fibre-optic gyro technology in one sensor.

Combining computing and sensing functions this way helped Honeywell meet its targets of reducing acquisition cost by 30%, size and weight by 40% and application cost by 50%, while increasing maintainability by 60% and both dispatchability and reliability by 100%. In the Hawker Horizon, Honeywell expects to reduce weight by at least 45kg compared with its SPZ-8000 system in the Hawker 1000, eliminating 23 line-replaceable units and at least doubling system reliability.

The Horizon cockpit will feature five side-by-side, 200x250mm LCDs - two primary-flight and two multi-function displays and an engine-instrument and crew-alerting system. Displays with cursor-activated "soft keys" for various functions are being considered. Raytheon will evaluate the utility of soft keys, and the various cursor-control options, using a prototype display in Honeywell's Cessna Citation III testbed.

Other elements of the Horizon avionics suite include Honeywell's latest Primus 880 high-power turbulence-detection radar with 460mm phased-array antenna; dual FMZ-2000 flight-management systems with performance computer and autothrottle; and integration of a range of AlliedSignal avionics, including enhanced ground-proximity warning system with terrain database.

Source: Flight International