How does Winscore calculate finish altitude?

Tom,
You are noting the altimeter correction factor and
then applying it to the new altimeter setting, aren't
you?

If I get 29.90 from AWOS at Minden and then set it
into my altimeter and it reads 4800 feet, I must readjust
the setting to make it read field elevation (4720)
and then note the altimeter correction factor (- .1)
which I must apply to any new altimeter setting I get
in the air.
JJ

At 17:12 30 July 2007, 5z wrote:
On Jul 30, 7:21 am, John Sinclair
wrote:
I don't find this to be true, Andy. Altimeters need
to be re-set primarily when landing at a destination
1000's of miles away from the takeoff location.

We have an AWOS right on the airport, so I set the
mechanical and 302
to this shortly before takeoff. When I check the altimeter
after 4-6
hours, the change is typically 1-200' - and usually
puts me lower.
Really unsettling if I'm on a marginal glide and the
air looks stable
ahead.

-Tom

On Jul 30, 2:12 pm, John Sinclair
wrote:
Tom,
You are noting the altimeter correction factor and
then applying it to the new altimeter setting, aren't
you?

When I set my altimeter per the Kollsman window, it reads field
elevation +/-20' so there is no correction factor needed.

In a contest, if the field elevation is 1234' MSL, and if there is a
nearby altimeter available, I'll typically see something like
1200-1250, so I just set my 500' finish to be at 1800' MSL as
indicated on the altimeter.

FYI, it's really easy to sync the Kollsman indication to match the
field elevation, but probably not something to be done outside a
repair station.



-Tom

On Jul 30, 6:21 am, John Sinclair
wrote:
I don't find this to be true, Andy. Altimeters need
to be re-set primarily when landing at a destination
1000's of miles away from the takeoff location. I find
my altimeter to be surprisingly accurate when landing
at my takeoff location after a 4 hour flight. This
is true with the SN10 altineter, also.
JJ

JJ,

My observation is based on analysis of many of my own flight logs. I
am so convinced this 100 foot difference is valid that, if there is no
local altimeter setting available, I set my altimeter 100ft lower
before starting final glide. I had planned to spend this evening
reviewing your recent flight logs but I don't find you as a registered
OLC contestant. Perhaps you could check a few of your logs,
measuring the exact difference between on ground altitude at takeoff
and on ground altitude after landing and report the results. If you
use Parowan logs please allow for the difference due to runway slope.
( most days I was there this year takeoffs were from the low end and
landings ended at the high end)

Andy

As this discussion has shown, if you set field elevation
before takeoff and don't change it, then finish with
500 feet on your altimeter, Windscore won't flag you
with a penalty. That's what I do and I haven't been
tagged with a finish penalty yet. Start gate is another
story......................
JJ

At 02:36 31 July 2007, Andy wrote:
On Jul 30, 6:21 am, John Sinclair
wrote:
I don't find this to be true, Andy. Altimeters need
to be re-set primarily when landing at a destination
1000's of miles away from the takeoff location. I
find
my altimeter to be surprisingly accurate when landing
at my takeoff location after a 4 hour flight. This
is true with the SN10 altineter, also.
JJ

JJ,

My observation is based on analysis of many of my own
flight logs. I
am so convinced this 100 foot difference is valid that,
if there is no
local altimeter setting available, I set my altimeter
100ft lower
before starting final glide. I had planned to spend
this evening
reviewing your recent flight logs but I don't find
you as a registered
OLC contestant. Perhaps you could check a few of
your logs,
measuring the exact difference between on ground altitude
at takeoff
and on ground altitude after landing and report the
results. If you
use Parowan logs please allow for the difference due
to runway slope.
( most days I was there this year takeoffs were from
the low end and
landings ended at the high end)

Andy

"Andy" wrote in message
ups.com...
My observation is based on analysis of many of my own flight logs. I
am so convinced this 100 foot difference is valid that, if there is no
local altimeter setting available, ....... snip
Andy

I also beleive the 100 foot (plus or minus) from take-off to landing is
valid.
It is called diurnial effect. The suns heating of the ground during the day
causes the pressure in the lower atmosphere to decrease slighly causing the
altimeter to read about 100 feet higher than actual. This is on most days,
we all know that weather facts are sometimes variable. Of course if you
land next to some mountains where there is down flow during the late
afternoon your milage (pressure) may vary.

Duane

At 13:54 30 July 2007, Kirk.Stant wrote:
I think if you have a 'zero penalty' band pilots will
tend to use it. I can't figure the difference between
and 700' finish with a 200' band and a 500' finish.

Andy,

My point is that the current system encourages you
(the racing pilot)
to shave the 500' limit as close as you can, but at
the risk of losing
a lot if you miscalculate - or opt for a low altitude
dash to a rushed
landing to minimize your losses. Plus it encourages
expensive gadgets/
software (as I now realize that my SN10 will show the
info I need, for
example - priced one lately?) and clock watching at
the finish.

Providing an 'altitude-neutral' band to finish in should
remove the
incentive to aim for the bottom, since there would
no longer be a
benefit to be gained, while the risk of losing a lot
would be a strong
incentive to aim for the top of the finish band. The
band should be
big enough to hit easily with a properly set regular
altimeter (I
think 200' would work) without being so big the adjustment
for
altitude becomes 'gameable'.

Heck, how about adding one second for every 2 feet
below the top -
that works out to a 1.2 knot final climb - which wouldn't
hurt you
much if you were 20 ft low, but would still encourage
not finishing
199 ft low (who wants to give away time, after all).

The addition of 'no racing after the finish' (i.e.
if below the
bottom, the 'hard deck' in fighter speak, you get your
finish and
penalty right there and can forget about a straight
in finish and
concentrate on making a safe low altitude landing)
would additionally
discourage high risk finishes.

I know, I know, enough whining, this is pretty much
beat to death -
time to start bashing 2-33s again...

Cheers,

Kirk



I must be missing the point Kirk - if there is no penalty
for finishing at the bottom of the 'neutral band' then
I'd be inclined to shoot for the bottom of it to save
time. With the 30 seconds per 100' penalty band my
behavior changes - in that case I'd shoot for the top
of the penalty band but wouldn't worry too much about
a few feet of miscalculation or misjudgement. Are you
thinking of my 'penalty band' when you say 'neutral
band'? Maybe that's it.

9B

On Jul 31, 1:06 pm, Andy Blackburn
wrote:
At 13:54 30 July 2007, Kirk.Stant wrote:





I think if you have a 'zero penalty' band pilots will
tend to use it. I can't figure the difference between
and 700' finish with a 200' band and a 500' finish.

Andy,

My point is that the current system encourages you
(the racing pilot)
to shave the 500' limit as close as you can, but at
the risk of losing
a lot if you miscalculate - or opt for a low altitude
dash to a rushed
landing to minimize your losses. Plus it encourages
expensive gadgets/
software (as I now realize that my SN10 will show the
info I need, for
example - priced one lately?) and clock watching at
the finish.

Providing an 'altitude-neutral' band to finish in should
remove the
incentive to aim for the bottom, since there would
no longer be a
benefit to be gained, while the risk of losing a lot
would be a strong
incentive to aim for the top of the finish band. The
band should be
big enough to hit easily with a properly set regular
altimeter (I
think 200' would work) without being so big the adjustment
for
altitude becomes 'gameable'.

Heck, how about adding one second for every 2 feet
below the top -
that works out to a 1.2 knot final climb - which wouldn't
hurt you
much if you were 20 ft low, but would still encourage
not finishing
199 ft low (who wants to give away time, after all).

The addition of 'no racing after the finish' (i.e.
if below the
bottom, the 'hard deck' in fighter speak, you get your
finish and
penalty right there and can forget about a straight
in finish and
concentrate on making a safe low altitude landing)
would additionally
discourage high risk finishes.

I know, I know, enough whining, this is pretty much
beat to death -
time to start bashing 2-33s again...

Cheers,

Kirk

I must be missing the point Kirk - if there is no penalty
for finishing at the bottom of the 'neutral band' then
I'd be inclined to shoot for the bottom of it to save
time. With the 30 seconds per 100' penalty band my
behavior changes - in that case I'd shoot for the top
of the penalty band but wouldn't worry too much about
a few feet of miscalculation or misjudgement. Are you
thinking of my 'penalty band' when you say 'neutral
band'? Maybe that's it.

9B- Hide quoted text -

- Show quoted text -

I guess I'm not making myself very clear. I see the "neutral band" as
an area where there is no advantage anywhere in it - you get the time
it would take to climb to the top added if you finish below the top.
So you might as well climb the extra 200 ft and not risk a low finish,
but having done that, if you run into sink and finish 100' below the
top (but 100' above the bottom) you only get dinged by the time you
would have spent getting that 100 ft back. But if you push it and aim
for the bottom of the neutral band, you get time added (time it would
have taken to climb to the top), and if you miss low - then you get a
big hit (no finish or rolling finish). To me, that would encourage me
to plan my final glide to the top of the window, but not worry too
much if I'm 50 ft low when I finally cross the line. If I saw I was
getting too close to finishing at the bottom, then I could slow down
early enough or change my finish strategy.

I guess that the crucial calculation would be the climb rate used to
equalize the neutral band. A bad choice would obviously create a bias
towards finishing high or low. Better to bias towards finishing high?

And maybe 200' is too much - perhaps a 100 ft window?

I'm no mathematician, so my logic and assumptions may be false, but it
seems doable to have the rule create a "window" that we can aim for
(assuming we want to win, and are not going to climb way above the
optimum finish height).

A side note - which of the current glide computers/PDA programs figure
the final glide to the finish line, instead of to the finish point
(center of the finish circle)? I'm pretty sure my SN10 figures to the
center of the finish circle, not the actual line - Dave Nadler, if you
are reading this, could you chime in?

Kirk