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Here's a nice piece of aviation artwork which you might
enjoy. Click on the thumbnail for a larger view. If you would like to
use this as a  background picture on your desktop, then right-click
on the large picture and choose Set as Wallpaper from the
drop-down menu that appears. It will then automatically be saved as a
file named Internet Explorer Wallpaper.bmp in your Windows
folder and come up on your desktop. This procedure applies to Internet
Explorer 5 and Windows 98, and I guess there is a similar option
available in other browsers. If you already have a background
image previously saved from the web in this way and do not want to lose
it, then
before you save this picture, go into your Windows folder,
right-click on the file called 'Internet Explorer Wallpaper.bmp', choose
rename from the drop-down list, then type a suitable new name for
your existing picture file - make sure you add the file extension .bmp - and press
return.
After you've set the new picture as a wallpaper
image, it's not a bad idea to rename this new file immediately as well,
then you're ready to save any other pictures you fancy for your
wallpaper collection. If you go into Control Panel from your
desktop (Start/Settings/Control Panel) and choose Display,
the re-named files will also appear amongst your list of available
wallpapers on the Background tab of the Display
Properties dialog box.
about the picture . . .
The picture is a painting by Wilfred Hardy,
GAvA, entitled 21st Century Team. It depicts a Eurofighter
FGA1 in the colours of No 74 Squadron operating with an E-3D Sentry AEW1
of No 8 Squadron. As also stated on the home page, it is reproduced by
kind permission of The Royal Air Force Benevolent Fund Enterprises
and comes from the cover of their book Brace by Wire to Fly-by-Wire.
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clear decal sheets
On ModelFlight #10, I referred to some impressive
decals I had seen on a static model which had been produced on a PC,
printed on ordinary paper and then photocopied on to clear decal
sheets that had been purchased from Hannants. This UK company
specialises in the supply of decals for the plastic modeller, and
looking at their web-based catalogue I found Xtradecal Clear Decal sheets,
A4 size, £3.25 (EU) or £2.77 (Export). http://www.hannants.co.uk |
The majority of unexplained
failures of radio systems are caused by receiver battery supply
problems. Most of these failures can be avoided if an on-board battery
monitor such as the Cyclops Tri-Colour Rx Monitor, obtainable from your
model shop under part numbers FDL006-009, is used in the model. The
monitor will give an early warning of all of the problems mentioned
below. We strongly recommend that you use this monitor.
The 'Cyclops' comes in
straight, right-angle and 6V types |
Reverse charge cell failure
NiCad battery cells are fairly
robust and while they will stand quite a lot of abuse, they can be very
rapidly destroyed by reverse charging. Cells damaged by reverse charge
do not always fail immediately and it may take five or six
charge/discharge cycles before the cell finally fails. Apart from
connecting a charger with a reversed polarity, there are other ways in
which battery cells can be reverse charged. |
Battery
discharge below 4V
When NiCad cells are connected
in series, such as in a receiver battery pack, the individual cells in
the pack need to have more or less the same capacity so that they all
discharge at the same rate. Inevitably, the match is never perfect and
if discharge is carried on too long, one of the cells will become
discharged to zero volts. During any further discharge, the remaining
cells will force electricity through the flat cell and reverse charge
it. Normally it is considered safe to gently discharge a four-cell NiCad
pack to 4 volts since at that level no individual cell is likely to be
completely discharged.
JR's NEB480 monitor doubles as
a lost model alarm |
Excessive
current from a low capacity battery
If powerful or numerous servos
are used, the instantaneous current from the receiver NiCad can be many
amperes. All batteries have an internal resistance that causes the
terminal voltage to fall when heavy currents are
drawn. NiCad cells have a
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relatively low internal resistance but at the
current levels drawn by the more powerful of today's servos, with a
partly discharged battery, the voltage drop caused by the internal
resistance can actually be greater than the cell voltage and this can
cause an effective reverse charge.
Black Wire Corrosion
The black corrosion of
connecting wires is caused by the corrosive gases given off by NiCad
cells when they are overcharged. Initially, the corrosion of the wires
is not important in itself and the problem arises from the accompanying
corrosion of the connector pins and the switch harness switch contacts.
The corrosion causes a high resistance contact that prevents the passage
of the electricity to the receiver. When this corrosion is present, it
can lead to very intermittent operation with the system working after
the connections are moved, say when checking, and then failing after a
few flights as the corrosion builds up again. |
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space is here
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us about your particular branch of the hobby, d-i-y projects, review a
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web! |
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on the postbox and get in touch now!
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