Avionics News December 2014 - 22
HEAD-UP DISPLAYS OFFER A LOOK AHEAD
Continued from page 21
needed so the aviator never must go "head down" to
see airspeed, altitude, attitude or an approach aid. They
have evolved from systems for big, expensive businessturbine aircraft into less-costly, right-sized systems for
general aviation aircraft.
Any pilot who's flown an instrument approach with
one of these enhancements understands the benefits
of keeping eyes out the window during those critical
minutes before final. These systems provide a degree of
reality heretofore unavailable to help pilots deal with
some of Mother Nature's most-challenging weather.
The basics: A projector and combiner
The initial civil-aircraft head-up systems tended to
take up a lot of space to deliver only some basic data.
Above and beyond the left command seat of the
airliner, a projector beamed its green-light image
at a multilayered piece of glass called a combiner
that serves as a beam splitter; and a data generation
computer provides the image projected by the projector
with the same parallel-light effect originated with the
optical gun sight of 1900.
Throughout the years, the light source in the projector
evolved from a cathode ray tube - the old television
technology - to compact LED-source devices. The
technology progressed to optical wave guides that create
the imagery directly in the combiner - without a projector
- and scanning lasers are the latest evolution, able to
produce both the data needed and video imagery as highly
resolved and smooth as modern graphics displays.
The computer needs a source for the information it
feeds to the display-generating unit, and the move into
digital flight instruments serves to further simplify and
streamline the information processing.
In the course of development, HUD and HGS systems
have shrunk in size and power consumption to a point that
almost any nominal four- or six-place aircraft should be able
to accommodate the hardware. The variety and capabilities
of the hardware available today is the best it's ever been.
The arrays of options available to install a head-up
display or head-up guidance system are as broad and varied
as ever - albeit still largely restricted to the businessturbine class of aircraft. Some efforts have been made to
bring options to smaller piston-powered Part 23 aircraft
have, so far, failed to catch on in a significant way.
But for the business-turbine folks, the race to
smaller, more-compact systems bodes well for the
long-term potential for piston-aircraft options.
Among the smallest so far is Rockwell Collins' EVS3000. The EVS will be offered with the company's HGS3500, one of today's smallest head-up display packages.
Rockwell Collins terms the HGS-3500 a "compact"
package with the image source of the compact HUD
situated above the combiner with "substrate-guided
optics" distributing the imagery through the glass. This
approach not only makes the package small, it also
wholly eliminates the need for a projector.
Embraer is among the airframe makers to tap this
package as a future option on its new Legacy 450
and Legacy 500 mid-light and mid-size business jets.
Data with which to drive the HUD system should be a
seamless fit since Embraer tapped Rockwell Collins' Pro
Line Fusion integrated avionics as standard on both jets.
The HGS-3500, however, is an option.
With its own new enhanced-vision sensor, Rockwell
Collins now offers operators a HUD package with
the real-world advantages of enhanced-vision system
technology. But then, this came as no surprise, since the
whole philosophy behind Pro Line Fusion has always
been to fuse enhanced and synthetic vision for display to
pilots - head-up and head-down.
Honeywell's own Visual Guidance System originally
was designed specifically for the company's Primus Epic
integrated avionics suite, and it continues to serve with
Honeywell's compact HUD 2020 electro-optical
overhead unit generates an image on a lightweight
combiner that provides the pilot with head-up, realtime flight and aircraft performance data. The HUD
2020, designed from a complete systems perspective
to integrate fully with the entire suite of Honeywell
standard avionics on board Gulfstream's stable of
large business jets, remains a popular option in the
planemakers latest cockpits. Ditto for the versions
installed in Dassault Falcon's EASy versions of the
same Honeywell integrated avionics packages.
Italy's PAT Avionics debuted its "G-HULP" system
at EAA AirVenture in 2012, and generated significant
interest at Sun 'n Fun the following spring thanks to
its compact size, low power drain and self-contained
architecture. The company touts G-HULP as the HUD for