I forgot to add, anyone who intends not to compete should really take a
more convervative stance and garner as much RF headroom as possible. It
just may save your butt one day...
Simon Van Leeuwen wrote:
Adequate, under competition conditions, allows you to safey see your
aircraft at maximum comfortable range consistently. A this range,
headroom (the acceptable range past this point) could be minimal or
non-existant.
I can not define adequate for you and your system, but for me and my
radio systems, GND range testing looking for worst case reception can be
less than 100ft from the aircraft. However while airborne, I have
sufficient range to adequately see and percieve what is happening to my
aircraft (actually seeing parts of the airframe may be only 50% of the
time while completing a thermalling circle at very long range). The
airborne range check is actually more useful to me than the GND range
check. For me the GND range check "after" determining maximum airborne
range is what gives me an idea of acceptability. I can then interchange
the two values to understand whether a radio installation in a new
airframe is going to be problematic.
I don't advise everyone run out and use this standard, as it takes above
average understanding of your particular radio system such that you know
where(!) you start to lose communication while airborne. PCM-based
systems are excellent for this, as while you no longer have control for
a period of time, the aircraft does not act up (last position is held
until signal is re-acquired). This takes some guts to put up an aircraft
and explore the limits, but boy do you get accurate and useable results.
The chances of losing an aircraft to this form of range testing has
never resulted in an aircraft loss.
To understand your particular system, no matter what you do, ALWAYS do
the same test repeatedly, either with antenna element mounted or not.
It makes zero difference to the system under test, but to be able to
compare any results over a period of time, the testing parameters must
be as close to identical as possible. Otherwise test comparisons are
useless.
I want to reinterate at this point that looking for the worst-case
reception is extremely important. By this, I mean rotating the airframe
while watching the PED to determine which attitude presents the least
reciprocity (range) as far as the RX is concerned. There is nothing
worse than someone who wishes to get airborne as quickly as possible,
and performs hap-hazard range checks just for the sake of it by walking
out some specified distance, and upon achieving this figures he/she has
a green light to fly...
Simon Van Leeuwen
RADIUS SYSTEMS
PnP SYSTEMS - The E-Harness of Choice
Cogito Ergo Zooom
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