yeehaa

Hans Holbein added these comments in the current discussion du
jour ...

Had to Google KIAS, Knots Indicated Air Speed. I would say,
yes, nautical miles or knots would be the unit for this. Since
I am not a pilot nor do I play simulation games, I don't know
if the one you refer to differentiates between ground speed and
indicated air speed but whether it is in statute miles/hour or
nautical miles/hour or knots I don't know.

Im no pilot neither.

Im still learning all the things needed to go online for combat
with other weirdos. ;-)

The usual airspeed indicator is a tube on some undisturbed place
at the aircraft, the pitot-tube.

Those things have been around since people first wanted to know how
fast they were flying!

With lesser air pressure at increasing height you need more
speed to induce the pressure in this tube to indacate the
airspeed.

Yeah, has some things to do with relative air pressure across the
wing and at the particular place the pitot tube breaks the airflow.
Can't say I'm much of an aerodynamicist so I don't really
understand this stuff very well past playing with them with a small
wind tunnel in my undergraduate Engineering Fluid Dynamics class.

So indacated airspeed IAS differs from true airspeed
TAS which means the speed realtively to the surface.
With no wind influence, as I recall the fomula is
TAS=IASx(1+ Heightx0,02/300)
But I might have forgotten something.
Its ~8% pus in 3000ft and ~44% in 20000ft
If I'm correct, in 20000ft you fly 540knots while your indicator
shows only 375knots.

I was thinking of something else, rather than the math used to
adjust real vs indicated air speed. I was thinking about the often
BIG difference between air speed and ground speed where either a
head wind or tail wind can cause the air speed indicator to be way
off compared to actual distance over the ground.

I can't fault your math as I've never delved into this stuff, nor
the changes that occur the closer the plane gets to Mach 1 and many
other factors affecting even the most basic flight characteristics.

Im not very comfortable with the anglo-saxon systems, but over a
long term I think the metric system will do the race.
Resistance is futile!
SCNR

You know, over here in The Colonies ALL of our measures are Metric
except that by law, things which are sold to consumers must also
carry a traditional or English conversion. This makes some very
strange numbers being printed on bottles of soda pop! And, I have
the same problem with Metric that you do with English/traditional
units. I can easily do the conversions, sometimes in my head with a
little effort, but I have never been able to think in metric - I
always have to do a conversion. Even my years of science in High
School and 4 years in Engingeering School weren't enough.

I doubt that the US will EVER really convert to Metric. Just too
much inertia from people resistant to change, thus there's no
political capital to utilize and much political danger so no pol
will risk a major proposal for change. So, we have dual units even
on things like our car speedometers, and of course, I have to have
two sets of wrenches in my tool box!

Have a pleasant day and enjoy your flight simulator!

--
HP, aka Jerry

"Government is NOT the solution to our problems, it IS our
problem!" - Ronald Reagan