"Lars P. Hansen" wrote in message
k...
OK, here we go: Could devices like this not also be used to detect
thermals?
The description in the link below about how the laser "sees" minute dust
particles in the air seems to be well suited to thermals.

Happy New Year to all,
Lars Peder

Probably. It also talks about the ability to show a 3-D representation of
the airmass movement around the aircraft. Since it's eye-safe, it probably
has a fairly short range.

This ties back to Bill Daniels' wish for a variometer with a negative
delay -- to be able to see what the airmass is doing a few seconds in front
of the glider.

It's unlikely that it's as inexpensive or will be as inexpensive as handheld
GPS, but if you were serious about performance measurement, it might be
able to pay for itself in a reduced number of tows to characterize a given
aircraft or configuration. So it might make sense for a university
department or a manufacturer. At least it's light enough and rugged enough
to consider mounting it on a sailplane.

Still, some of the civilian applications (shooting, sailboats) were in
more-or-less recreational areas, so perhaps they expect to be able to keep
the cost down.


Tim Ward



Lars P. Hansen


"Eric Greenwell" wrote in message
...
Tim Ward wrote:


I found this laser sensor on the web:


http://www.navysbir.brtrc.com/succes...navsea_p3.html
Not many details.
Assuming it's accurate enough, one could be used to get the glider's
vertical speed through the airmass.
Now you have both horizontal and vertical velocity measurements
relative
to
the local airmass.
That should simplify the problem.

A Google search turned up laser airspeed sensors that, in concept, could
be used to measure L/D directly from the glider. Some of them were good
for the low speeds we need to measure sink rates. So, have one pointing
forward, one pointing down, divide the forward speed by the sink rate,
and ta-da! L/D. It wouldn't matter what the airmass was doing, since the
measurements are relative to the airmass.

Unfortunately, none of the units I saw seemed to be small, cheap, or
readily available, as their audience appeared to be military types or
rather expensive aircraft.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA