FAA PTS "Slips to Landing" requirement vs No-spoiler landings

On Sep 10, 6:07*pm, "kirk.stant" wrote:
The past few weekends I've been watching some our our club students
being instructed on and practicing slips to a landing (i.e."no spoiler
landings") in preparation for their Private check rides. *Gliders used
were our 2-33 and Blanik. *I've also seen no-spoiler landings being
demonstrated in our G-103 *- some quite nicely judged, I might add!

But I've been wondering about the utility and safety of this practice,
and whether it's taught in other countries - and if so, how it's
taught.

I realize that a no-spoiler approach is always an eventuality, and our
club even had one several years ago in a G-102 that left the glider in
the cornfield off the far end of the field, but it seems to me that
the skill learned in a slipped approach in a 2-33 may not really
transfer to a Discus 2 or other slippery glass ship, and that
conversely, realistic training - slipping all the way to touchdown, no
spoilers allowed - in a glass 2-seater (unless one has the luxury of a
really big field) could be somewhat hazardous.

It kind of reminds me of the old multi-engine requirement to
demonstrate Vmc at low altitudes, which was finally changed when the
authorities realized that they were killing more pilots in training
than in actual engine failures!

On the other hand, I've tried them in glass, including my Ls6 (which
does not recommend slips to a landing), and concluded that they are a
serious emergency that needs to be carefully thought out ahead of
time, and can only be safely practiced by breaking down into two
segments: *First, no spoilers, slip to aim for the middle of the
field, then recover and land normally with spoilers as required; and
second, position the glider so as to be approaching the threshold at a
safe speed and altitude, then close spoilers, establish a slip, and
continue with the no-spoiler landing.

Comments? *I'm especially interested in hearing how this is handled in
other countries.

Kirk
66

Realistic requirement for a number of reasons.
1) It is useful for additional sink rate in many ships- makes my '28
come down much faster.
2) Spoilers do freeze shut - we see it in the Winter in the East.
3) Equipment does fail.
4) It is a useful exercise in aircraft control
5) Folks we are training may fly ships that don't have the really good
dive brakes of the modern ships.
6) It's kinda fun. No spoiler- no brake spot landings are a challange.
FWIW
UH

"Bruce" wrote in message
...

My thoughts are that you need to open the brakes to balance the drag and
lift asymmetry. Then you can fly the aircraft through the resulting
descending roll and recover.

In the case I am talking about, that option was not available. One spoiler
stayed connected to the linkage and fully operable while a broken bracket
had effectively disconnected the other one, leaving it closed. The only was
to return the glider to balance flight was to close the spoilers. (Yes, a
1-spoiler slip may have been possible, but that is a lot to figure out when
you are on downwind and are suddenly presented with a strange control
situation).

Vaughn

"bildan" wrote in message
...
wrote:

Nah, you can do a really cool slip with one spoiler.

That would depend on the glider.

Vaughn

In Italy we have to practice during instruction the side "wing" slip
landing, for license examination, but the main reason is to be able to
do it but in case you are too high, when you are final in landing and
want to create your final glide even more steep
Maurizio

On Sep 11, 12:07*am, "kirk.stant" wrote:
The past few weekends I've been watching some our our club students
being instructed on and practicing slips to a landing (i.e."no spoiler
landings") in preparation for their Private check rides. *Gliders used
were our 2-33 and Blanik. *I've also seen no-spoiler landings being
demonstrated in our G-103 *- some quite nicely judged, I might add!

But I've been wondering about the utility and safety of this practice,
and whether it's taught in other countries - and if so, how it's
taught.

I realize that a no-spoiler approach is always an eventuality, and our
club even had one several years ago in a G-102 that left the glider in
the cornfield off the far end of the field, but it seems to me that
the skill learned in a slipped approach in a 2-33 may not really
transfer to a Discus 2 or other slippery glass ship, and that
conversely, realistic training - slipping all the way to touchdown, no
spoilers allowed - in a glass 2-seater (unless one has the luxury of a
really big field) could be somewhat hazardous.

It kind of reminds me of the old multi-engine requirement to
demonstrate Vmc at low altitudes, which was finally changed when the
authorities realized that they were killing more pilots in training
than in actual engine failures!

On the other hand, I've tried them in glass, including my Ls6 (which
does not recommend slips to a landing), and concluded that they are a
serious emergency that needs to be carefully thought out ahead of
time, and can only be safely practiced by breaking down into two
segments: *First, no spoilers, slip to aim for the middle of the
field, then recover and land normally with spoilers as required; and
second, position the glider so as to be approaching the threshold at a
safe speed and altitude, then close spoilers, establish a slip, and
continue with the no-spoiler landing.

Comments? *I'm especially interested in hearing how this is handled in
other countries.

Kirk
66

On Sep 11, 12:01*am, Bruce wrote:
vaughn wrote:
"Mike the Strike" wrote in message
....
I do know of one where the spoiler handle on a Grob 103
broke after they had been deployed and jammed full open, resulting in
an off-field landing.

And I know of a case where just one spoiler deployed on a glider. *Causes a
nasty uncommanded roll. *The only solution (once you figure out what is
going on) is to close the spoilers and proceed without them.

Vaughn

Single spoiler deployment has caused at least one fatal accident.

If a linkage fails resulting in asymmetric airbrake deployment it is
possible to run out of options very quickly.

My thoughts are that you need to open the brakes to balance the drag and
lift asymmetry. Then you can fly the aircraft through the resulting
descending roll and recover. Depending on your height and speed it may
be quite pressing to land, it may also be quite pressing to reduce speed....
However - if this happens in a high energy state (where else?) you may
already have a lot of yaw and roll inertia by the time you get the other
airbrake open. Especially on a long winged open class ship there may
just not be enough control authority left, and if you are very fast
and/or very close to the ground the options are limited.

To overcome the differential lift caused by the yaw you may need full
rudder.
To limit the speed and avoid terrain you may need large elevator deflection.
To reverse the roll and return to level flight you almost certainly will
need full aileron.

You are unlikely to find such a high G, rolling pull up close to , or
over Vne with airbrakes deployed in the manual.

There is a reason for that "max manoeuvre speed" entry...

A little math says that at 250km/h and 300m (~1000")AGL a 30 degree
descent angle will give you less than 8 seconds to avoid terrain.

40 years ago I was involved in building and testing a glider with
spoilers for roll control instead of ailerons. Preliminary flight
tests were done on normal gliders rigged to permit one spoiler to be
deployed at a time.

The first thing we learned is that spoilers don't do what they are
generally thought to do.

The results of asymmetrical spoiler deployment vary dramatically with
airspeed since drag increases with the square of airspeed but lift
which is 'spoiled' pretty much remains constant with airspeed. (Any
lift reduction is transient since the glider quickly re-establishes
equilibrium at one G flight where lift =weight.)

The bottom line was that below some airspeed like 50kts, weak roll
(~10% of aileron authority) was the dominate result and above that
powerful yaw was the dominate result. We found it best to regard
differential spoilers as yaw control devices. Thus the concept of
roll spoilers was a failure.

In one iteration, spoilers were rigged to the pedals with the normal
rudder fixed in neutral. With yaw spoilers, ailerons and elevator, we
had a remarkably agile glider - albeit not a particularly efficient
one.

So, the accidental deployment of one spoiler will result in powerful
yaw not roll which leads me to the subject of using one in a slip.

When slipping a glider one quickly finds the limit is available rudder
authority. With full rudder one can use only about 15 degrees of bank
while maintain a straight track. However, with one spoiler deployed,
the pilot has far more 'rudder' authority in the direction of the open
spoiler and a far steeper bank can be used. This results in an
incredibly steep approach.

This situation is 'dangerous' only to the extent the pilot doesn't
understand how to control his partially disabled aircraft.

I think it's a useful maneuver in the same way that boxing the wake is
-- it tells the examiner you're really in charge of the aircraft and
pattern planning. We don't really do it for broken spoilers, that's a
once in a gazillion event. That's why the new PTS does not require an
actual landing with spoilers, only demonstration of glide path control
using spoilers alone.

The PTS should also require slips WITH spoilers not slips INSTEAD of
spoilers. That's the maneuver you will use, when too high, to get in
to a field, etc. Many pilots have no idea how steeply you can in fact
come down. We'll just have to train that on our own. I've been having
fun with students -- the challenge is, set up a landing so that you
will use full slip and full spoiler on final. If you have to back off,
you buy the beer (after flying)

John Cochrane

At 07:00 11 September 2009, Derek Copeland wrote:
I once had one spoiler fully out due to a failure of a diecast aluminium
bracket in a Grob Astir. This broke in flight, with a loud bang as the
left airbrake suddenly sucked open and stayed there. I then found that I
needed almost full right aileron and rudder to conteract the roll and
yaw
to the left. I was only about 900ft AGL at the time.

The solution I worked out was to open the the other airbrake, which
still
worked, and then make the best more or less straight ahead landing that
I
could into a field. I had to sideslip the glider to get in, but walked
away from it and didn't further damage the glider.

BTW, this and another case is why many Grob Astirs have a little perspex
inspection window under the wing, so that you can see the offending
bracket.

Getting back to the original subject, we do teach no airbrake approaches
in the UK as a post solo exercise, just in case the airbrake mechanism
fails, or the brakes freeze shut while wave soaring. I have made a video
of such an exercise, but you float an awfully long way in ground effect,
which is why I eventually told the student to open the brakes, as it
was
the last flight of the day and we wanted to stop somewhere near to the
hangar. See:

http://www.youtube.com/watch?v=5t7xnls2w5k

This was done in a K13, which sideslips very nicely and very much more
effectively than most glass gliders. With a lot of slip on, the ASI will
usually totally misread.

Derek Copeland

P.S. I know the Yanks call a sideslip a 'forward slip' before someone
pulls me up on that!


At 02:02 11 September 2009, vaughn wrote:

"Mike the Strike" wrote in message
...
I do know of one where the spoiler handle on a Grob 103
broke after they had been deployed and jammed full open, resulting in
an off-field landing.

And I know of a case where just one spoiler deployed on a glider.
Causes
a
nasty uncommanded roll. The only solution (once you figure out what is

going on) is to close the spoilers and proceed without them.

Vaughn

P.S. I know the Yanks call a sideslip a 'forward slip' before someone
pulls me up on that

If the British call our "forward slip" a "sideslip" what do they call
a mild slip that you would use primarily to counteract a crosswind?
Thanks

On Fri, 11 Sep 2009 18:45:03 +0000, Ron Ogden wrote:

If the British call our "forward slip" a "sideslip" what do they call a
mild slip that you would use primarily to counteract a crosswind? Thanks

Nothing - I was taught to fly a crabbed approach and to kick it straight
just before touchdown. AFAIK the crosswind countering slipped approach
isn't taught in the UK.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

At 18:45 11 September 2009, Ron Ogden wrote:

If the British call our "forward slip" a "sideslip" what do they
call
a mild slip that you would use primarily to counteract a crosswind?
Thanks


How about a crosswind landing? There are two ways of doing this - wing low
or crabbing.

Derek Copeland

I concur with Kirk. Spoilerless approaches in glass requires a major
rethink of the approach and hopefully lots of practice in similar
(glass) ships prior to the real-deal. I do not believe, based on lots
of real-world experience, and observation, that most pilots could get
their glass ships on the ground in less than 3-4000 ft of runway
"first pass" without significant prior training, thought, and
practice.

Other than for the practice and proficiency, I do not know why anyone
would slip a 2-33 or similar to get rid of altitude. Merely pushing
over to higher speeds is very effective in such a draggy ship.

In preparation for the first flight of my AS-W12, I slipped anything
that was available to a spoilerless landing: Caproni (bad idea), AS-
W20, AS-W17, K21, Grobs, LS-4, etc. After those, the 12 was no big
deal. This type of approach and landing needs a serious change in
your paradigms and pretty much freaks out everyone who might be
watching as it is distinctly "abnormal". As the PIC, it is a bit
distracting seeing your "friends" lining the runway and exchanging
wager $$ based on your next landing. Major kudos to Larry and Jane
Barrett for their faith in me during my practice phase.

Like others have said, and similar to the Landing On Tow, spoilerless
approaches improve pilot skill and awareness and make an otherwise
boring day quite a bit more exciting. All of this is Good. Mastery of
spoilerless approaches = better pilot!