using less spoiler just before the flare???

Greetings,

This may get many comments, but I'm curious as to the consensus.

On a recent training flight (wasn't me...) the student was advised to go
to about 2/3 spoiler just before the flare.

Normal approach, field was made, on target for a nice touchdown.

When I was getting instruction, I was always encouraged to progress
toward full spoiler in the pattern and to ideally get to a full spoiler
and stabilized approach once the target touchdown point was "in range".
Advice given was that full spoilers minimized the potential for
ballooning and provided maximum drag and minimized lift. i.e. get on
the ground and stay there and make a positive effect to get the glider
stopped. Additionally, I've always been of the mind set that unless
there was an unusual circumstance, that spoiler changes near the ground
were usually best avoided.

Any other thinking as to a benefit in reducing spoiler just before the
flare?

Just pondering...

Gary

Gary Emerson wrote:
Any other thinking as to a benefit in reducing spoiler just before the
flare?

a) Some gliders (not the Duo 8^) cause sufficient sink rate at full
extension to make for a rather firm arrival if not reduced.

b) Some gliders actuate the wheel brakes at full extension, and some
instructors are known to get overly concerned about generating a screech
and a nice puff of smoke.

Marc

"Gary Emerson" wrote in message
. net...
When I was getting instruction, I was always encouraged to progress toward
full spoiler in the pattern and to ideally get to a full spoiler and
stabilized approach once the target touchdown point was "in range".


I was not taught (nor did I teach) any such thing. First of all, spoiler use
is type-specific. If you have a glider with very effective spoilers, you are
less likely to need them full on. If you are flying something with wimpy
spoilers, you might routinely fly your whole final to touchdown with them full
on.

I was taught that the theoretical "ideal", perfectly-planned and executed
pattern would have about 50% spoilers throughout the full pattern. If you are
at 50%, then you have maximum authority to either increase or decrease your
glide angle as conditions warrant.

Vaughn

Vaughn Simon wrote:
I was taught that the theoretical "ideal", perfectly-planned and
executed
pattern would have about 50% spoilers throughout the full pattern.

I've heard this before, and wondered about why it's "ideal" to have
spoilers open during the downwind and base leg. What was the reason your
instructors gave you?

I've always flown - and taught - the downwind and base legs with the
gear down, spoilers closed. This way, my turns to base and final are as
high as possible, and the final is longer, giving me more time to
stabilize it, to make corrections (especially big ones), and inspect the
landing area.

If you are
at 50%, then you have maximum authority to either increase or decrease your
glide angle as conditions warrant.

I agree with this technique, and it is what I strive for on final. I do
use somewhat less spoiler if the glider has a strong landing flaps (ASW
20, e.g.), or responds significantly to just cracking the spoilers.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Oct 25, 7:12 pm, Gary Emerson wrote:
Greetings,

This may get many comments, but I'm curious as to the consensus.

On a recent training flight (wasn't me...) the student was advised to go
to about 2/3 spoiler just before the flare.

Normal approach, field was made, on target for a nice touchdown.

When I was getting instruction, I was always encouraged to progress
toward full spoiler in the pattern and to ideally get to a full spoiler
and stabilized approach once the target touchdown point was "in range".
Advice given was that full spoilers minimized the potential for
ballooning and provided maximum drag and minimized lift. i.e. get on
the ground and stay there and make a positive effect to get the glider
stopped. Additionally, I've always been of the mind set that unless
there was an unusual circumstance, that spoiler changes near the ground
were usually best avoided.

Any other thinking as to a benefit in reducing spoiler just before the
flare?

Just pondering...

Gary


One principle not commonly taught, but worth understanding, is that
spoilers
do somewhat different things in parts of the pattern.
I teach the use of approximately 1/2 spoiler from a point abeam the
touchdown.
This uses "safety altitude up at a rate proportional to distance left
to touchdown
thus providing a fairly constant rate of descent and pretty much
constant height
margin.
This assumes steady airspeed selected for conditions.
Adjust spoilers moderately for changes in angles to the touch down
point.
On final, the effect of spoilers changes.
In the early part of final , they are rate(and angle at constant
speed) of descent
control.
As we transition into the flare and touchdown phase the spoilers
become rate of
deceleration control thus determining when the glider no longer has
enough speed to fly.
Teaching this principle of leaving the spoilers alone(unless sink or
other factor dictate) allows a smooth transition into the flare
without losing the drag needed to land at the target.
This method leads to pilots who can land at low energy with minimal
extra float.
It also means that only the pitch control hand needs to do something
which is much easier
for students to master.
Some try to "improve on what we teach" thinking less spoiler near the
ground will give slower sink
and smoother landings. After bouncing around in ground affect and
landing poorly and
long, they come back to what they are taught
From the start, I teach that last part of final, if possible, is with
full spoilers to get pilots used
to steep final like is needed landing in a field . This way they will
revert to habits that work well
during their first "stressful" outlanding.
Hope this was not too "windy".
UH

wrote:

I teach the use of approximately 1/2 spoiler from a point abeam the
touchdown. This uses "safety altitude up at a rate proportional to distance left
to touchdown thus providing a fairly constant rate of descent and pretty much
constant height margin. This assumes steady airspeed selected for conditions.
Adjust spoilers moderately for changes in angles to the touch down
point.
On final, the effect of spoilers changes. In the early part of final
, they are rate(and angle at constant
speed) of descent control. As we transition into the flare and touchdown phase the spoilers
become rate of deceleration control thus determining when the glider no longer has
enough speed to fly.

How do you use the landing flaps on something like an ASW 20 or 27? Use
them only on final? Save them for situations where spoilers aren't enough?

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Fri, 26 Oct 2007 06:12:29 -0700, wrote:



One principle not commonly taught, but worth understanding, is that
spoilers
do somewhat different things in parts of the pattern.
I teach the use of approximately 1/2 spoiler from a point abeam the
touchdown.

Very interesting - I guess you are flying a very tight apporach
pattern, starting very high on downwind, right?

I'm just wonderung, because if we'd do this with the ASK-21 in the
traffic pattern at my home airfield (height at downwind about 650 ft
above ground), we wouldn't even reach the airfield.


Bye
Andreas

On Oct 26, 8:41 pm, Andreas Maurer wrote:
On Fri, 26 Oct 2007 06:12:29 -0700, wrote:

One principle not commonly taught, but worth understanding, is that
spoilers
do somewhat different things in parts of the pattern.
I teach the use of approximately 1/2 spoiler from a point abeam the
touchdown.

Very interesting - I guess you are flying a very tight apporach
pattern, starting very high on downwind, right?

I'm just wonderung, because if we'd do this with the ASK-21 in the
traffic pattern at my home airfield (height at downwind about 650 ft
above ground), we wouldn't even reach the airfield.

Bye
Andreas

LIkely we are teaching a steeper approach profile than you are.
This is because we want pilots used to a fairly step approch on final
to allow shortest landing in a field. It is also easier to judge a
steeper angle.
Pls take the 1/2 spoilers(airbrakes whatever) with a bit of a grain of
salt.
The point is to establish a rate of descent on the order of about
500ft/min
and adjust from there.
UH

Probably a better idea to teach that they are used
as required, rather than automatically opening them
at a fixed positon irrespective of height. Doing this
could end in tears.


At 14:12 26 October 2007, Eric Greenwell wrote:
wrote:

I teach the use of approximately 1/2 spoiler from
a point abeam the
touchdown. This uses 'safety altitude up at a rate
proportional to distance left
to touchdown thus providing a fairly constant rate
of descent and pretty much
constant height margin. This assumes steady airspeed
selected for conditions.
Adjust spoilers moderately for changes in angles to
the touch down
point.
On final, the effect of spoilers changes. In the early
part of final
, they are rate(and angle at constant
speed) of descent control. As we transition into the
flare and touchdown phase the spoilers
become rate of deceleration control thus determining
when the glider no longer has
enough speed to fly.

How do you use the landing flaps on something like
an ASW 20 or 27? Use
them only on final? Save them for situations where
spoilers aren't enough?

--
Eric Greenwell - Washington State, USA
* Change 'netto' to 'net' to email me directly
* 'Transponders in Sailplanes' http://tinyurl.com/y739x4
* 'A Guide to Self-launching Sailplane Operation' at
www.motorglider.org

Whilst I have enjoyed reading this thread there is one thing bugging me.
you all keep referring to spoilers, when in actuality I believe you are
referring to airbrakes.
Spoilers, as those of you that have and do fly gliders / motor gliders
which utilise spoilers will know how different
their behaviour is to that of airbrakes.
sits back and awaits #flames#


Mark Dickson wrote:
Probably a better idea to teach that they are used
as required, rather than automatically opening them
at a fixed positon irrespective of height. Doing this
could end in tears.


At 14:12 26 October 2007, Eric Greenwell wrote:
wrote:

I teach the use of approximately 1/2 spoiler from
a point abeam the
touchdown. This uses 'safety altitude up at a rate
proportional to distance left
to touchdown thus providing a fairly constant rate
of descent and pretty much
constant height margin. This assumes steady airspeed
selected for conditions.
Adjust spoilers moderately for changes in angles to
the touch down
point.
On final, the effect of spoilers changes. In the early
part of final
, they are rate(and angle at constant
speed) of descent control. As we transition into the
flare and touchdown phase the spoilers
become rate of deceleration control thus determining
when the glider no longer has
enough speed to fly.
How do you use the landing flaps on something like
an ASW 20 or 27? Use
them only on final? Save them for situations where
spoilers aren't enough?

--
Eric Greenwell - Washington State, USA
* Change 'netto' to 'net' to email me directly
* 'Transponders in Sailplanes' http://tinyurl.com/y739x4
* 'A Guide to Self-launching Sailplane Operation' at
www.motorglider.org