Remote thermal detection

Forty years ago I put some effort into electrostatic
L/R detection of thermals. The big probelm is the vertical
component of the general gradient which is at least an order of magnitude
bigger than the horizontal part.
This meant that using tip mounted sensors, the vertical distance
between the tips times the vertical gradient would have to be
compensated for; these days with micro computers and roll rate
sensors,this might not be so difficult.
My approach was to mount probes fore and aft and try to fly
a constant pitch angle. (speed)

There were fields I could detect but never resulting in
finding a thermal by turning slowly L and R.
A real sucess was detecting a field across an airmass boundary
( a weak pseudo front, shown by haze) and confirmed by
several passes each direction. There was weak lift
but the haze variation gave this away and I only detected the
field as I flew through it.
The 25m plus spans of some gliders could allow a better
signal.

I await further initiatives with interest.

John Firth, old but no longer bold pilot.

On a few occasions, I have observed soaring birds fly quickly towards a
p=
oint where they found a thermal - sometimes a distance of about a
kilometer=
.. The speed and direction of them indicated to me that they were flying
to=
an objective and not just hunting randomly. If so, this means that they
c=
an detect thermals remotely using their senses. If we can figure out how
t=
hey are doing this, there is a chance we can build instruments to
replicate=
their method.
=20
=20
=20
Having studied the possibility of using electrostatic methods (thermals
a=
dvect space charge from the ground and dust devils are actively charged
by
=
particle collision), this is very short range and not likely the
mechanism
=
birds are using. I would guess it has to be visual.
=20
=20
=20
Mike

I suspect it is visual for birds. The have far better vision than we and
c=
an probably see small objects like seeds rising with the thermal. They
may=
also possess special visual processing centers in their brains evolved
to
=
detect thermals.

I suspect the "one shot" DARPA program works the same way by detecting
embe=
dded objects like dust and seeds moving across the field of view then
using=
powerful algorithms to process the data. Range the objects as they move
a=
cross the field and the direction and speed of the wind can be
determined.

What's interesting to me is the comment that the device will work out to
th=
e maximum effective range of currently fielded sniper rifles. .50
caliber
=
rifle ER's can exceed 3000 meters. There is also a comment elsewhere
indic=
ating the DOD wants to issue this to every soldier so it can't be too
expen=
sive.

On Wednesday, October 24, 2012 12:15:03 PM UTC-6, John Firth wrote:
Forty years ago I put some effort into electrostatic

L/R detection of thermals. The big probelm is the vertical

component of the general gradient which is at least an order of magnitude

bigger than the horizontal part.

This meant that using tip mounted sensors, the vertical distance

between the tips times the vertical gradient would have to be

compensated for; these days with micro computers and roll rate

sensors,this might not be so difficult.

My approach was to mount probes fore and aft and try to fly

a constant pitch angle. (speed)



There were fields I could detect but never resulting in

finding a thermal by turning slowly L and R.

A real sucess was detecting a field across an airmass boundary

( a weak pseudo front, shown by haze) and confirmed by

several passes each direction. There was weak lift

but the haze variation gave this away and I only detected the

field as I flew through it.

The 25m plus spans of some gliders could allow a better

signal.



I await further initiatives with interest.



John Firth, old but no longer bold pilot.



On a few occasions, I have observed soaring birds fly quickly towards a

p=

oint where they found a thermal - sometimes a distance of about a

kilometer=

.. The speed and direction of them indicated to me that they were flying

to=

an objective and not just hunting randomly. If so, this means that they

c=

an detect thermals remotely using their senses. If we can figure out how

t=

hey are doing this, there is a chance we can build instruments to

replicate=

their method.

=20

=20

=20

Having studied the possibility of using electrostatic methods (thermals

a=

dvect space charge from the ground and dust devils are actively charged

by

=

particle collision), this is very short range and not likely the

mechanism

=

birds are using. I would guess it has to be visual.

=20

=20

=20

Mike



I suspect it is visual for birds. The have far better vision than we and

c=

an probably see small objects like seeds rising with the thermal. They

may=

also possess special visual processing centers in their brains evolved

to

=

detect thermals.



I suspect the "one shot" DARPA program works the same way by detecting

embe=

dded objects like dust and seeds moving across the field of view then

using=

powerful algorithms to process the data. Range the objects as they move

a=

cross the field and the direction and speed of the wind can be

determined.



What's interesting to me is the comment that the device will work out to

th=

e maximum effective range of currently fielded sniper rifles. .50

caliber

=

rifle ER's can exceed 3000 meters. There is also a comment elsewhere

indic=

ating the DOD wants to issue this to every soldier so it can't be too

expen=

sive.



In about that same time frame I worked on a set of paper charts showing data collected with an airplane traversing Mojave Desert thermals in mid-afternoon. The sensors included field mills for electrostatic charge and aerosol detectors in addition to the usual - temp, humidity etc.. The only consistent indicator of a 'thermal' was rising air. I think any successful remote thermal detector will have to "see" air motion directly.

Bill D wrote
What's interesting to me is the comment that the device will work out to the maximum effective range of currently fielded sniper rifles. .50 caliber rifle ER's can exceed 3000 meters. There is also a comment elsewhere indicating the DOD wants to issue this to every soldier so it can't be too expensive.

Bill, please read Liam's comment above (4th message in thread). This
does not work for us. It requires firing a laser against a solid
target.

I have been studying this problem since 1984 and agree with all of
John Cochrane's points above. It will be good for soaring for the
reasons he cites and more. Just like GPS and all the other electronic
aids it will be rapidly accepted.
Technically, some passive or active (LASER or microwave) probing of
the clear atmosphere to detect the relative motion (subtracting your
vario) via backscatter from dust, bugs and pollen, along with image
processing algorithims, will probably be in the final solution.
I have compiled a database of relative papers on the technologies
involved he
http://www.ct-hanggliding.org/thermal.htm but it's getting a little
old now as new things develop.
Looking forward to seeing someone finally make this happen.