How Low to Spin??

Chris OCallaghan wrote:
Andy,

I guess my only comment is a question: Does it really make any
difference in what you see? Framing wires against the sky (if that's
your intent) requires being lower than the wires. Which in turn means
you are at risk of hitting other wires.

What is the genesis of this approach? It clearly requires advanced
energy management skills, so it isn't appropriate for low time pilots
(the majority) or lower peformance sailplanes. Was it suggested by
someone, or is it someplace you arrived through time and experience?

I'll give it a try at the home drome during my next few flights. But I
guess I'm still having trouble determining what advantage I have by
flying a base and final leg low and fast. Would you apply the same
method for an approach over tall trees? Even if it meant losing sight
of your intended touch down point during much of the final leg?

I'm not agreeing or disagreeing with Andy yet, but
let's consider for a moment the psychological effect of
this idea: perhaps it helps focus the pilot on the
objects between the glider and the intended touchdown.
Or helps orient the pilot to the type of terrain found
on the way in, or gets him lower so it's easier to determine wind
direction from small cues on the ground.

Again, I'm not advocating the idea, but there are some more
subtle points...
--

------------+
Mark Boyd
Avenal, California, USA

On Fri, 27 Aug 2004 18:02:44 UTC, (Kirk Stant)
wrote:

: But you
: shouldn't be jerking your head around while flying!

Except to scan for other aircraft.

Ian


--

On Fri, 27 Aug 2004 21:38:02 UTC, (Mark James
Boyd) wrote:

: "Oh yeah? He had an accident? I bet he
: didn't use the checklist!"

I once had someone try to persuade me to use a checklist for a winch
cable break. Yes, great, run through a list of actions which have to
be started within a second and completed within a few ... the idiot's
an instructor now, and feedback tells me that he's no less of an
idiot...


Ian


--

(Mark James Boyd) wrote in message news:412e8424$1@darkstar...


We had this discussion before. If the thermal is coming from a
stationary ground source, and the best performance is
zero sink in the thermal, doing it exactly as a ground
reference manuever (shallow upwind, steep tailwind) is correct.

Otherwise one is blown downwind of the thermal.

This was well discussed in threads about a year ago.

If one starts at 60 degree banks on the upwind, with
10+ knots of wind and zero sink, trying to core the thermal
on the downwind will be exciting...

Thermalling at any height is a thermal referenced maneuver. The
thermal is in the air, the maneuver is not ground referenced.

Visual inputs from changing ground speed must not be allowed to take
priority over airspeed control, and they will if you are not very
careful to keep airspeed in the scan.


Andy

I guess the question comes down to energy management.
At one extreme, if you come in low and slow on a long
final you run the risk of not being able to extend
your touchdown point should an obstacle become apparent.
At the opposite extreme, a short, high and fast approach
runs the risk of running too long on touchdown, even
with full spoilers.

I've opted for being a bit faster in the pattern to
keep some extra margin for wind gusts and to allow
more margin for moments of distraction turning base
or final. To keep total energy under control, this
means flying a bit lower pattern. Flying 70 knots instead
of 60 knots means about 50' lower in the pattern for
the same total energy. Obviously you'd start to slow
down before getting to treetops or other obstacles.


In a 'standard' approach you have to lose about 20
knots from final approach to touchdown. I need lose
30 knots, which means starting that process a few seconds
sooner. The flatter glidepath on short final means
that you are, for a brief period, at a lower angle
to your final touchdown point, so you do get a peek
at potential obstacles. I can't say that this has ever
directly benefitted me, but I do know of cases where
pilots have been too slow on final, with bad results.

9B

At 23:24 28 August 2004, Mark James Boyd wrote:
Chris OCallaghan wrote:
Andy,

I guess my only comment is a question: Does it really
make any
difference in what you see? Framing wires against the
sky (if that's
your intent) requires being lower than the wires. Which
in turn means
you are at risk of hitting other wires.

What is the genesis of this approach? It clearly requires
advanced
energy management skills, so it isn't appropriate for
low time pilots
(the majority) or lower peformance sailplanes. Was
it suggested by
someone, or is it someplace you arrived through time
and experience?

I'll give it a try at the home drome during my next
few flights. But I
guess I'm still having trouble determining what advantage
I have by
flying a base and final leg low and fast. Would you
apply the same
method for an approach over tall trees? Even if it
meant losing sight
of your intended touch down point during much of the
final leg?

I'm not agreeing or disagreeing with Andy yet, but
let's consider for a moment the psychological effect
of
this idea: perhaps it helps focus the pilot on the
objects between the glider and the intended touchdown.
Or helps orient the pilot to the type of terrain found
on the way in, or gets him lower so it's easier to
determine wind
direction from small cues on the ground.

Again, I'm not advocating the idea, but there are some
more
subtle points...
--

------------+
Mark Boyd
Avenal, California, USA

Andy Blackburn wrote:
I guess the question comes down to energy management.
At one extreme, if you come in low and slow on a long
final you run the risk of not being able to extend
your touchdown point should an obstacle become apparent.
At the opposite extreme, a short, high and fast approach
runs the risk of running too long on touchdown, even
with full spoilers.

In between, I suppose there is "high and slow" (perhaps the "normal"
pattern), and "low and fast" (what you seem to be using). I am curious
about how you decided "low and fast" was the best choice: conversations
with other pilots, testing both methods on fields (maybe with a
motorglider?), or ...?


I've opted for being a bit faster in the pattern to
keep some extra margin for wind gusts and to allow
more margin for moments of distraction turning base
or final.

What are you flying "a bit faster" than? The glider handbook
recommendation? The club instructor's opinion? Or just what you used to use?

To keep total energy under control, this
means flying a bit lower pattern. Flying 70 knots instead
of 60 knots means about 50' lower in the pattern for
the same total energy. Obviously you'd start to slow
down before getting to treetops or other obstacles.

What glider are you flying? 60 knots in calm air already sounds "a bit
faster" than most gliders would have to fly. Where is the yellow
triangle on your airspeed indicator?

How much wind would it take before you'd use _more_ than 70 knots? My
glider has the yellow triangle at 50 knots, and normally I wouldn't use
70 knots on final unless the wind was over 30 knots.



In a 'standard' approach you have to lose about 20
knots from final approach to touchdown. I need lose
30 knots, which means starting that process a few seconds
sooner. The flatter glidepath on short final means
that you are, for a brief period, at a lower angle
to your final touchdown point, so you do get a peek
at potential obstacles.

This "fast and low" approach sounds like something easily done at the
home airport, but would be tricky to do right going into a field you've
never seen before. Have you used this method at airports and into fields
you've been landed at before?

I can't say that this has ever
directly benefitted me, but I do know of cases where
pilots have been too slow on final, with bad results.

And there have been cases where pilots have been too fast on final, with
bad results.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Andy Durbin wrote:

We had this discussion before. If the thermal is coming from a
stationary ground source, and the best performance is
zero sink in the thermal, doing it exactly as a ground
reference manuever (shallow upwind, steep tailwind) is correct.

Otherwise one is blown downwind of the thermal.

This was well discussed in threads about a year ago.

If one starts at 60 degree banks on the upwind, with
10+ knots of wind and zero sink, trying to core the thermal
on the downwind will be exciting...

Thermalling at any height is a thermal referenced maneuver. The
thermal is in the air, the maneuver is not ground referenced.

Well, we went over this last year. I don't know how to look
up old RAS threads. Perhaps someone else does.
--

------------+
Mark Boyd
Avenal, California, USA

At 21:54 29 August 2004, Eric Greenwell wrote:
I am curious
about how you decided 'low and fast' was the best choice:
conversations with other pilots, testing both methods
on fields (maybe with a
motorglider?), or ...?

After seeing too many friends die in stall/spin accidents
- it's purely a consequence of my own paranoia with
flying too slow in the pattern.

What are you flying 'a bit faster' than? The glider
handbook
recommendation?

Yes.

What glider are you flying?

ASW-27B

This 'fast and low' approach sounds like something
easily done at the
home airport, but would be tricky to do right going
into a field you've
never seen before. Have you used this method at airports
and into fields
you've been landed at before?

Yes.

http://groups.google.com/groups?hl=e...roup=rec.aviat
ion.soaring


Mark-

Just make sure to click the 'RAS only' bullet, and
use the standard google search techniques...


Well, we went over this last year. I don't know how
to look
up old RAS threads. Perhaps someone else does.
--

------------+
Mark Boyd
Avenal, California, USA

Andy Blackburn wrote:

At 21:54 29 August 2004, Eric Greenwell wrote:

I am curious
about how you decided 'low and fast' was the best choice:

conversations with other pilots, testing both methods

on fields (maybe with a
motorglider?), or ...?


After seeing too many friends die in stall/spin accidents
- it's purely a consequence of my own paranoia with
flying too slow in the pattern.

I can see how the "fast" part can help, but not the "low" part. Being
low doesn't seem like an asset if you are worried about stalls and spins.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA