Final glide

I am not convinced by the argument for a 200 foot reserve to allow for pressure changes or obstructions. That almost implies that you would be ready to arrive at an arrival height of 200 foot. If you have zero set but plan to arrive at 800 foot then you will be able to cope with pressure changes or obstructions. If you plan to arrive well below circuit height I hope you are using visual judgement before you get too low.

I am interested by the point about the reserve being added to your finish height where your finish height is different from your arrival height at an airfield. How does this work? I don't have 'Finish is 1,000m below start set' as it doesn't normally affect me - if I start above 1,000 m on a flight for which the scoring will be affected that is another adjustment which I make mentally. In the UK the rule does not affect competition scoring but does affect our BGA Ladder. I have never flown with a finish other than at an airfield - is there a way to set the minimum height at a finish ring?

On Tue, 24 Sep 2019 07:44:48 -0700, waremark wrote:

I am interested by the point about the reserve being added to your
finish height where your finish height is different from your arrival
height at an airfield. How does this work? I don't have 'Finish is
1,000m below start set' as it doesn't normally affect me - if I start
above 1,000 m on a flight for which the scoring will be affected that is
another adjustment which I make mentally. In the UK the rule does not
affect competition scoring but does affect our BGA Ladder. I have never
flown with a finish other than at an airfield - is there a way to set
the minimum height at a finish ring?

I use LK8000 as my main navigation tool. It displays arrival heights as a
signed value, which is difference from your configured arrival height. So
with 1000 configured as your target arrival height, if it displays +200
its predicting you'll arrive 200 ft above target and if it shows -400 its
predicting arrival 400 ft below target.

That works for me.


--
Martin | martin at
Gregorie | gregorie dot org

At 14:44 24 September 2019, waremark wrote:
In the UK the rule does not affect competition scoring but
do=
es affect our BGA Ladder. I have never flown with a finish other than
at
an=
airfield - is there a way to set the minimum height at a finish ring?

With LXxxxx, just set the finish ring radius and a "safety height" of
500ft or whatever on the QNH page. The LX will then show the arrival
height margin at the ring, not the airfield. 0ft on the LX means you are
at the set ring-crossing height.

MC

And then you land out before arriving at the airfield! I cannot understand why people ever set finish rings at a height which isn't sufficient to ensure a comfortable arrival at the airfield.

On Tue, 24 Sep 2019 15:30:42 -0700, waremark wrote:

And then you land out before arriving at the airfield! I cannot
understand why people ever set finish rings at a height which isn't
sufficient to ensure a comfortable arrival at the airfield.

Looks reasonable to me: just set a small finish ring, say with a radius
equal to the distance from the airfield TP to the high key point for the
run being used on that day and ring height to what the destructors like
as high key height. That should be pretty close to putting you at the
start of what amounts to a text-book approach.

I'd try it myself, provided there's another flying day hiding amidst the
current rain and wind. However, although LK8000 7.0 allows a finish ring
to be specified, it doesn't allow a finish height to be input.

I feel a change request coming on....


--
Martin | martin at
Gregorie | gregorie dot org

At 23:02 24 September 2019, Martin Gregorie wrote:
On Tue, 24 Sep 2019 15:30:42 -0700, waremark wrote:

And then you land out before arriving at the airfield! I cannot
understand why people ever set finish rings at a height which
isn't sufficient to ensure a comfortable arrival at the airfield.

Looks reasonable to me: just set a small finish ring, say with a
radius equal to the distance from the airfield TP to the high key point
for the run being used on that day and ring height to what the
destructors like as high key height. That should be pretty close to
putting you at the start of what amounts to a text-book approach.


Mark,

If a Competition Director is setting a finish ring too low, have a word
with them. And also remember that you are PIC, not the CD. If you
need more height to land safely because of a stronger head wind,
weaker tail wind, pressure drop, bugs, rain or general nervousness,
the finish ring does not constrain you from crossing it above the
height set by the CD. For a given ring size, the CD will re-assess the
minimum height daily based on the minimum performance of gliders
competing and the conditions.

Martin,

See the BGA and IGC competition rules to understand properly what
a finish ring is about.

BGA:

A ring of specified radius (normally, but not exceeding, 3km) around
the finish point encompassing the contest site and the landing
circuits.

When a Finish Ring is specified, a minimum altitude related to glider
performance of the lowest performance glider in task group, terrain
and obstructions should be set. Unless there are specific
obstructions, the minimum altitude should be set to allow gliders to
just pass over the ring on a normal final for direct landing in the
expected prevailing wind.

For both the finish Line and Finish Ring, a viable direct landing
option must be available to allow finishers to land ahead without
turning after crossing the line or ring. A Control point should be
utilised as necessary to ensure compliance.

IGC:

A circle of specified radius (minimum 3 km) around the Finish Point
encompassing the contest site and the landing circuits.

Finish Ring is to be regarded as the preferred finish procedure as it
allows each pilot to slow down and concentrate on the landing
procedures and other sailplanes prior to landing.

Organisers are encouraged to use a Final Turn Point to align the
sailplanes with the desired direction of finishing.


You can download some logger files from the competitions at
Lasham to see how it works in practice.

MC

On Wed, 25 Sep 2019 10:49:26 +0000, Mike Clarke wrote:

Martin,

See the BGA and IGC competition rules to understand properly what a
finish ring is about.

My suggestion was for a way to use a finishing circle as the minimum
arrival height for a non-competition, e.g. BGA Ladder, xc flight, NOT
anything to do with a competition task.


--
Martin | martin at
Gregorie | gregorie dot org

Now who ever said making the perfect final glide was suppossed to be "comfortable" lol. If it is too comfortable you just left points on the table.

On Tuesday, September 24, 2019 at 4:36:30 PM UTC-7, wrote:
Now who ever said making the perfect final glide was suppossed to be "comfortable" lol. If it is too comfortable you just left points on the table.

I would be extremely nervous about making a final glide that would have me doing a straight-in final at max L/D. Under this scenario, if your glide computer is very accurate, half of the time you would be landing short. And anywhere I fly, landing short is not an option. I am with Mike: I don't regard it as a reserve, that IS the altitude that I want to arrive at. My real reserve is the altitude I have over that. Too many times I have seen that reserve evaporate along the way. You may encounter unexpected areas of sink or stronger headwinds than expected.

Tom

Truth, and a final glide made at max l/d tells me that the guy already screwed up. The perfect final glide is one that gets you home at the proper altitude and at the max speed. He just screwed up on both counts.