On 2004-11-12 13:38:00 -0500, (Brian Salt) said:


I'm researching a WWII airfield near where I live in Devon, U.K.

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with
finding the height of the balloon.

The control tower of this airfield was equipped with two pillars to
which theodolites could be attached/mounted. Apparently, these were
used to determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I
can see) that you need the horizontal distance to the balloon as well
as the angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.

Brian Salt.
Remove NS from address before replying.

The two pillars probably just meant they had two theodolites.

The method used is based an an assumed rate of ascent. Fill the balloon
with the correct amount of hydrogen or helium, and it would rise at a
calculated rate. Copy down the azimuth and elevation at timed
intervals, then use calculations & now a computer to come up with the
wind direction and speed. I did it all the time as a weather observer.
Just part of the job.




Pete

I am setting up to obtain my own data from radiosondes launched
from the Tucson airport. I track the balloon with a small dish (1 meter)
to obtain a good signal and when the sky is clear use a theodolite to
obtain angle as a function of time.
I have only started to track with the theodolite, maybe 4 or 5 times,
and so I don't have the experience of a seasoned observer.

My comment is that it is much harder to do than I thought. Even though
the airport is 5 miles to the south, the angular rates are such that
it is easy to lose track. I tried doing one minute recording to start
off with and have had mixed results. My skill level is getting better
but its still stressful so I am thinking about adding encoders to the
theodolite and logging the data.

My hat is off to WX observers that can track a balloon in high winds.
Maybe if I was at the launch point the rates would be mostly in
elevation making it less demanding.

A baseline of 22 feet sounds like it wouldn't be to useful as the ascent
rates for a standard balloon and fill are known. I would feel better as
an observer just to have a second observer in case I lost track or wrote
down the wrong reading, as I have. I find the mistake when I plot the
data if it's really off, but a second observer would really help.

Dan





Pete Ware wrote:
On 2004-11-12 13:38:00 -0500, (Brian Salt) said:


I'm researching a WWII airfield near where I live in Devon, U.K.

It appears that the meteorologists used balloons as part of the data
collection, but at that time they had no radar, etc., to help with
finding the height of the balloon.

The control tower of this airfield was equipped with two pillars to
which theodolites could be attached/mounted. Apparently, these were
used to determine the angle of ascent and the height of the balloon.

Does anyone have any idea how that could be done, given (as far as I
can see) that you need the horizontal distance to the balloon as well
as the angle to find the height? Or would the use of two theodolites
simultaneously, spaced at about 22 feet apart, allow the height to be
found without needing the horizontal distance?

TIA.

Brian Salt.
Remove NS from address before replying.


The two pillars probably just meant they had two theodolites.

The method used is based an an assumed rate of ascent. Fill the balloon
with the correct amount of hydrogen or helium, and it would rise at a
calculated rate. Copy down the azimuth and elevation at timed intervals,
then use calculations & now a computer to come up with the wind
direction and speed. I did it all the time as a weather observer. Just
part of the job.




Pete

In article E9sld.110274$cJ3.88730@fed1read06,
Dan Mckenna wrote:

rates for a standard balloon and fill are known. I would feel better as
an observer just to have a second observer in case I lost track or wrote
down the wrong reading, as I have. I find the mistake when I plot the
data if it's really off, but a second observer would really help.

I had 2 mini-cassette recorders - one with a timed count so I didn't
have to keep an eye on the clock. The other, with voice activation, for
recording the elevation and azimuth. Was a great idea, esp. with any
strong winds aloft. This one sat on the base of the theodolite - right
next to my mouth. That made it so much easier to record the data!



Pete

Pete Ware wrote:

In article E9sld.110274$cJ3.88730@fed1read06,
Dan Mckenna wrote:

rates for a standard balloon and fill are known. I would feel better as
an observer just to have a second observer in case I lost track or wrote
down the wrong reading, as I have. I find the mistake when I plot the
data if it's really off, but a second observer would really help.

I had 2 mini-cassette recorders - one with a timed count so I didn't
have to keep an eye on the clock. The other, with voice activation, for
recording the elevation and azimuth. Was a great idea, esp. with any
strong winds aloft. This one sat on the base of the theodolite - right
next to my mouth. That made it so much easier to record the data!

Pete

What amateur astronomers who are occultation observers do is have a
shortwave playing WWV time signals and record their voices and the
signals. You need good reception, of course. It eliminates problems
with variations in tape speed, but I don't know if you need that
degree of accuracy for theodolite work.

Cheers,
Russell
--
All too often the study of data requires care.

In the past I used a darkroom timer that was set to go off every minute.
The challenge has been on the days when the balloon will move out of the
field or through scattered clouds. If I keep my eye to the theodolite
and keep the elevation and azimuth knobs moving at a constant rate then
momentary loss say due to clouds, power lines or UFOs can be worked
through as I can pick it up on the on the other side as long as I keep
turning the knobs.

I have been able to peak the signal using my dish and
read the elevation and azimuth display to re acquire.

I also predict the balloon track by using the NOAA READY predicted ETA
40 km sounding, running it through a program called balloon track and
then running my own program that calculates the apparent position from
my location. sometimes thats all I need.

The other week I saw a burst a little past sunset and it was
spectacular when the balloon turned in to a field of stars.

I will obtain a voice recorder.

Dan




R. Martin wrote:
Pete Ware wrote:

In article E9sld.110274$cJ3.88730@fed1read06,
Dan Mckenna wrote:


rates for a standard balloon and fill are known. I would feel better as
an observer just to have a second observer in case I lost track or wrote
down the wrong reading, as I have. I find the mistake when I plot the
data if it's really off, but a second observer would really help.

I had 2 mini-cassette recorders - one with a timed count so I didn't
have to keep an eye on the clock. The other, with voice activation, for
recording the elevation and azimuth. Was a great idea, esp. with any
strong winds aloft. This one sat on the base of the theodolite - right
next to my mouth. That made it so much easier to record the data!

Pete


What amateur astronomers who are occultation observers do is have a
shortwave playing WWV time signals and record their voices and the
signals. You need good reception, of course. It eliminates problems
with variations in tape speed, but I don't know if you need that
degree of accuracy for theodolite work.

Cheers,
Russell

In article ,
(Pete Ware) wrote:

*From:* Pete Ware
*Date:* Sat, 13 Nov 2004 17:33:18 -0500


I had 2 mini-cassette recorders - one with a timed count so I didn't
have to keep an eye on the clock. The other, with voice activation, for
recording the elevation and azimuth. Was a great idea, esp. with any
strong winds aloft. This one sat on the base of the theodolite - right
next to my mouth. That made it so much easier to record the data!


Some people have all the technology!

In article E9sld.110274$cJ3.88730@fed1read06,
(Dan Mckenna) wrote:

to have a second observer in case I lost track or wrote
down the wrong reading

That might well be the reason for the second pillar, as a confirmation of
the readings, especially considering the short distance between them.

The balloon would have been launched from the same point, i.e. not more
than a few feet from the theodolites.

as the ascent
rates for a standard balloon and fill are known.

I wonder if that applied in 1942? No reason why not, I suppose.