"Kirk Stant" wrote in message
om...
"tango4" wrote in message
...
The major problem with current HUD systems is that they are projected
onto a
screen screwed to the instrument panel turtledeck. Fine if you are a
fighter
jock and want to keep your eye on the bandit in front of you. Also good
for
IFR types who actually don't need to look out the window anyway.

What is really needed in sailplanes are head mounted displays that keep
an
image hovering in front of the pilot wherever his head is. A sailplane
pilot
only looking out ahead is almost as bad as one focussed on a PDA
strapped to
his leg.


Ian

Your description of current HUDs is somewhat misleading. HUD work by
projecting images, collimated to infinity, on a clear "combining
glass" on top of the instrument panel, in the pilots normal line of
sight. The projected symbology - attitude, heading, airspeed,
altitude, etc. is superimposed on the real world with a direct
correlation - in other words a 5 degree pitch up using the HUD scale
is a true 5 degree pitch, not a shrunk symbolic display as on a small
attitude indicator. Newer HUDs also allow projecting FLIR or LLTV
images - also collimated at infinity - on the HUD, so you have a
"virtual reality" display; cool at night. The importance of the
infinity collimation of the display is that you do not have to refocus
your eyes when looking at a HUD, you see the symbology when focused at
long distance. That is absolutely not true when "coming inside" to
read old fashioned steam gauges!

The downside is all the optics are HEAVY and power hungry, so don't
count on seeing them in a glider soon.

The newer fighters have Helmet-mounted displays that project all the
HUD symbology on their helmet visor. Still heavy, big, and power
hungry.

What I think we need for gliding is a nice big color navigation
display to replace the sectional chart that is becoming more and more
difficult to fold in our small cockpits - something that I can pull
out, look at, then put away to continue flying. Let's face it, after
awhile you can fly any glider by feel and audio vario, anyway.


Kirk

I have to agree with "tango4" that good glider pilots don't spend much time
looking straight ahead or "heads down" inside the cockpit.

Kirk, you are right that the current generation of HUD is heavy and power
hungry but it doesn't have to be. I once built a benchtop breadboard HUD
with semi-mirrored Mylar and plastic Frenel lenses - it worked great and
weighed less than 4 ounces including the LED light source. That little
experiment convinced me that there is a better way even though it was
technically possible.

Head mounted displays are coming fast and I think they will find a place in
glider cockpits. The latest from LeadTek
http://www.leadtek.com.tw/hmd/x_eye_1.shtml is a SVGA OLED display that
could be used with the 12V "car computers" now available. It appears that
the X-Eye would interfere with the pilots vision, however. We would need
"see-through" displays mounted on sunglass frames that give full peripheral
vision. It's nice to see an 800x600 OLED display though.

For now, I think I would find the panel mounted display a better solution,
but if sunlight readability remains a problem, eyeglass mounted displays may
be the interim solution. The neat thing about the modular x86 computers is
that the display can be replaced at will just like changing desktop
monitors.

Bill Daniels