Rotorcraft Avionics Modernization Trends

1. The cockpit of a rotorcraft is a maj loc for avionics eqpt, incl con, monitoring, comm, nav, weather, and anti-collision sys. The majority of rotorcraft drive their avionics using 14 or 28 volt DC elec sys; however, large, more sophisticated hels have AC systems operating at 115V 400 Hz. There are several maj vendors of flt avionics, incl Honeywell (which now owns Bendix/King, Baker Electronics, Allied Signal, etc), Rockwell Collins, Thales Group, Garmin, Narco, and Avidyne Corporation. A complete avionics suite for a modern hel usually comprises:-a.

 Communicationsconnect the flt deck to the gr, and the flt deck to the passengers. On board communications are provided ac intercoms, while ac communications provide the backbone for safe flt, the tac sys are designed to withstand the rigors of the B fd. UHF, VHF Tac (30-88 MHz) and SatCom sys combined with ECCM methods, and cryptography secure the communications. b. Navigation is the determination of posn and dir on or above the surface of the Earth. Avionics can use satellite-based sys (such as GPS and WAAS), gr-based sys (such as VOR or LORAN), or any combination thereof.

Older avionics required a pilot or navigator to plot the intersection of sig on a paper map to determine an ac's loc; modern sys, like the Bendix/King KLN 90B, calculate the posn automatically and display it to the flt crew on moving map displays.c. Monitoring Glass cockpits started to come into use with the Gulfstream G-IV pvt jet in 1985. These sys display sensor data that allows the ac to fly safely.

Much info that used to be displayed using mechanical gauges appears on electronic displays in newer ac. Almost all new ac incl glass cockpits.ARINC 818, titled Avionics Digital Video Bus, is a protocol used by many new glass cockpit displays in both commercial and mil ac. Fig 2:- Bell 412 Glass Cockpit.d.

Ac flt con sy hels have means of automatically controlling flt. They reduce pilot workload at imp times (like during landing, or in hover), and they make these actions safer by 'removing' pilot error. The first simple auto-pilots were used to con heading and altitude and had limited auth on things like thrust and flt con surfaces. In hels, auto stabilization was used in a similar way. The old sys were electromechanical in nature until very recently. The advent of fly by wire and electro actuated flt surfaces (rather than the traditional hydraulic) have inc safety.

e. Weather sys such as weather radar (typically Arinc 708 on commercial ac) and lightning detectors are imp for ac flying at night or in inst met conditions, where it is not possible for pilots to see the weather ahead. Heavy precipitation (as sensed by radar) or severe turbulence (as sensed by lightning activity) are both indications of strong convective activity and severe turbulence, and weather sys allow pilots to deviate around these areas.f. Msn or tac avionics mil ac have been designed either to deliver a wpn or to be the eyes and ears of other wpn sys. The vast array of sensors aval to the mil is used for whatever tac means req.

As with ac mgmt, the bigger sensor platforms have msn mgmt cptrs.g. Electro-Optics sys incl Fwd Looking Infrared (FLIR), and Passive Infrared Devices (PIDS). These are all used to provide imagery to crews. This imagery is used for everything from Search and Rescue (SAR) through to acquiring better resolution on a tgt. h.

ESM/DAS or Electronic sp measures and defensive aids are used extensively to gather info about threats or possible threats.They can be used to launch devices (in some cases automatically) to ctr dir threats against the ac. They are also used to determine the state of a threat and ident it.2.

The rapid advancement of hel avionics sys technology has underpinned the dev of rotorcraft ops, and the hel avionic sys instl in future hels will play a vital role in meeting increasingly demanding operational needs. Areas where new dev are likely to have a maj impact on future rotorcraft ops and capability incl:- a. The core hel avionics system with the intro of integrated modular avionics technology. b.

Hel cockpits with inc emphasis on integrated human centered design. c. Day/ni all-weather sys fusing info from databases and sensors to improve the pilot's situational awareness. d.

Hel flt con sys, with widespread adoption of fly-by-wire, and the intro of enhanced con augmentation. Further explanation of two advanced application avionics in hel con sys is given below:- (1)Autopilot. The autopilot sys consists of elec actuators or servos connected to the flt cons. The no and loc of these servos depends on the type of sys instl. A two-axis autopilot con the hel in pitch and roll; one servo con fore and aft cyclic, and another con left and right cyclic.

A three-axis autopilot has an addl servo connected to the anti-torque pedals and con the hel in yaw. A four-axis sys uses a fourth servo which con the collective. These servos move the respective flt cons when they receive con comds from a cen cptr. This cptr receives data input from the flt insts for attitude ref and from the nav eqpt for nav and tracking ref.

(2)Fly by Wire. The term "fly-by-wire" implies a purely electrically-signalled con sys. However, it is used in the gen sense of cptr-configured cons, where a cptr system is interposed b/w the operator and the final con actuators or surfaces.This modifies the manual inputs of the pilot in accordance with con parameters. These are carefully dev and validated in order to produce max op eff without compromising safety.

So far, the only in production hels with fly-by-wire cons are the Kazan Hels Ansat, a lt twin cert in 2004, and the Eurocopter/Agusta/Fokker NH90 mil tpt ac. Both have hydraulic actuators. Fig 3:- NH-90 Hel 3. Concl.

Fifty years of research and dev in the rotary-wing fd have produced numerous improvements since the first flight of the R-4B. The hel today is no longer an oddity but an integral part of our daily life.The desire to take off and land vertically and fly in the earth's boundary layer has persisted, and technology and dedication have accommodated that desire. We have seen that the advent of adv avionics techs have had a profound impact on the utility and acceptance of the hel. The future of the hel is clearly assured and adv rotary-wing ac, with an addl degree of comfort, are ready to extend the performance and utility.

In future, avionics will cont to dev at faster pace and keep easing out the versatile tasks of pilot. Army Avn must decide to upgrade its avionics arsenal in wake of concepts like LIC and NCW.