SCAT Electronic News July 6 1999
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- Category: Archive 1999
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SCAT Electronic News July 6 1999
Table of Contents
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Editorial [and BlackMagic] Perambulations
Slanic - Kaynes
looking - Brokenspar
Hot News from Hermann
Editorial [and BlackMagic] Perambulations
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Because I had to Oslo on business July 11 to 16, I looked at
my FAI FF calendar and found that the following weekend was the
Antonov Cup in Kiev. What a coincidence ! Now Kiev is not exactly
next door to Oslo, but it's a whole lot closer than Redeondo Beach.
So we're going to take a few days and do some flying. I hope to meet
some more SCAT Electronic News readers face to face. Also when I go to events
near here I always take some BlackMagic electronic timer stuff, on this
trip my luggage is limited [after all I do have my 'real' business
I have to do !], but if anyone needs timers or parts, let me know
as soon as possible and I will try and help.
Slanic
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On hearing the "news" about the salt mine, I asked the Romanian Modelling
Federation and Marius Conu replied as follows:
Nothing to worry about.
Just a slice of the little salt mountain slided into the salt lake.
I have called the Salt Mine and talked to the elevator people. It was for
the first time they knew about the catastrophy.......
I think this is likely to be more accurate than deductions from news
agency stories.
Ian
looking
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Roger, perhaps you can find room for this inquiry.....
I am looking for a resource that can provide some of the services Joe
Maxwell gave us in the past.
Cutting ribs for tapered sections, in sets , for wing panels. Milling (
positive ) forms for vacuum forming carbon shells for wing
sections. Joe worked from a diagram, or from computer data.
Previously, forms were made from Obechie wood, which
is suffering from successive forming at 25 inches of mercury. Like to
have aluminum, or perhaps some tooling composite
made to take that pressure and 250 F.
Thanks
This email address is being protected from spambots. You need JavaScript enabled to view it., or Brokenspar, Box1104, Birmingham, MI 48012
Temperature
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Roger,
Bill Bogart is correct (as we've grown to expect) regarding temperature
measurement. Is a real problem in getting accurate
readings of low velocity air temperature, outdoors, with the sun shining and
a number of hotter objects around.
Air is essentially transparent to solar radiation, so it gets heated
by convection from solid objects that absorb sun rays. In the process
the thermistor is heated above air temp also, but its small size
enables better convection and closer to air temp, than say a car.
Since a car, or the ground can be 20-50F above air temp, it is
interesting to use a Thermal Sniffer to check this thermal boundary
layer surrounding a solid object & find most of the action happens
in the first inch from the object. I often thought we were going
to great lengths to see how high we could get the sensor when it
probably is better closer to the ground which, after all, is the
source of the thermal.
For Thermal Sniffing, the standard thermistor is very slow.
Even with shrink tubing removed, it's time constant is about
15 seconds. Doesn't sound like much, but can delay thermal peaks
by over a minute!
Modified a Sniffer with a smaller, much faster, thermistor, but
most modellers that tried it were used to the slower units.
The real application for the fast ones is with recording units
where it can help determine the size of the bubble.
A final comment on air temperature measurement:
The Weather Bureau provides a useful service by supplying temperature
data from many sites around the country. The louvered doghouses
they use are less than ideal shields and the sensors are slow enough
to miss and delay the peaks. Hats off to anyone who can locate a
thermal, or even true air temperature, with their setup.
Herman Andressen
...................
Roger Morrell
