Troubling story and some questions

Dave,

Thanks for posting your experience. I am glad you
survived.

I fear your situation may have been worse than you
suspect.
Not knowing the actual atmospheric conditions at the
time and place of your event, I used ICAO standard
day conditions, and standard lapse rate, to compute
your TAS. I used my antique E-6B, inputting 18,000
feet, -21C, and 138K IAS. I ignored compressibility,
figuring it was insignificant at your Mach and altitude.
The result was 183K TAS, significantly higher than
your estimate.

Two thoughts come to mind: 1) Beware of using 'rules
of thumb', and 2) perhaps a professional inspection
of your aircraft is warranted.

Regards,

Fred W.




At 06:06 31 December 2007, wrote:
Hi Gang
Last week Minden had some excellent wave soaring.
Off tow at 7.7k
msl and within minutes up to 18k. I decided to go up
north skirting
Reno Intl. I had the transponder on and was monitoring
Reno Approach.
My goal was to try and fly as fast as possible maintaining
an altitude
very close to 18k by speeding up in lift and slowing
down in light
lift or sink. This worked well for the first 35 miles
where my IAS
(indicated air speed) ranged between 50 knots and
110 knots flying
never less than 17k. Then I got into some real lift
and pointed the
nose down and noticed my Becker transponder registering
18.2k which
is, of course, a no no. I then glanced at the IAS.
It read 138 knots
which is 165 knots TAS. (Every 1000 feet of altitude
above sea level
results in an error of 1.5% in IAS.) So what to do?
If I pulled the
spoilers at that speed, the shock might destroy them
or the glider. So
I gently pulled the stick back and translated speed
into altitude
going above 19k. At about 70 knots I pulled the spoilers
and got
myself down to below 18k. I wonder if ATC caught that?
Why was this so
bad? Well the VNE at sea level for the SparrowHawk
is 123 knots and it
has been demonstrated that at 171 knots the wings come
off. This
really gave me cause for concern. How quickly one can
get into trouble
by not paying attention. In the future I will fly slower
and use the
spoilers to compensate for excessive lift so as to
maintain altitude.
This story raises some questions about VNE at various
altitudes
which should be of interest to all of us glider pilots.
I Googled
combinations of words such as 'flutter altitude', 'VNE
altitude' and
'aircraft breakup altitude' to try and come up with
information on
whether the flutter/breakup characteristics of an aircraft
are less at
altitude than sea level at the same TAS. Intuitively
it would seem so
but intuition may not work here. I found nothing useful.
I know that
the World's ultimate high altitude motor glider the
U2, which was
designed in the 50s, had much study done on it with
regard to its
operating speed window of about 20mph (stall to breakup)at
80k feet
msl. There should now be declassified documents on
those studies which
might answer my questions. I would appreciate any pointers
anyone. If
I find anything useful I will summarize it on RAS.
Flying is often unforgiving of errors and I will
definitely be more
vigilant after this wake up call.
Dave

wrote:

My goal was to try and fly as fast as possible maintaining an altitude
very close to 18k by speeding up in lift and slowing down in light
lift or sink.

It's perfectly fine to do this for fun, and I'm sure you know that this
"Anti-McCready" tactic is the most inefficient possible.

noticed my Becker transponder registering 18.2k which is, of course,
a no no.

Transponder altitude is measured based on the standard atmosphere
pressure setting (QNE) and is not related at all to the 18'000 ft
ceiling which is based on the actual atmosphere pressure setting (QNH)
to which your altimeter should have been set.

So what to do? If I pulled the spoilers at that speed, the shock might
destroy them or the glider.

I've read further down that you flew a Sparrowhawk which I don't know.
But every glider I do know (all of them JAR certified European gliders)
allow for spoiler operation up to Vne. Sure, if you just yank those
spoilers fully open at Vne, you *will* break or at least bend something,
but if you hold the handle with a firm grip and operate them carefully,
then you're perfectly fine. After all, those spoilers are *designed* to
limit the dive speed at Vne! Of course, verify this with your POH first.

This story raises some questions about VNE at various altitudes
which should be of interest to all of us glider pilots. I Googled

You shouldn't need to Google, it should be right in your POH. Again, I
don't know the Sparrowhawk, but all the glider POHs I've seen so far
list Vne vs altitude. I usually write down these numbers and stick them
somwhere onto the instrument panel.

On Dec 31, 10:21�am, Eric Greenwell wrote:
wrote:
Then I got into some real lift and pointed the
nose down and noticed my Becker transponder registering 18.2k which
is, of course, a no no.

Not really - our 18,000' limit is measured with the altimeter, typically
set by adjusting it to field elevation (msl) while on the ground. Your
transponder was reporting the altitude measured by the encoder, which is
set to 29.92 to measure "pressure altitude". These two measurements can
vary by a thousand feet or more at 18,000', depending on the weather.

As some of the other posters have pointed out, determining flutter
speeds is a tricky business. "Fundamentals of Sailplane Design"
discusses altitude effects on pages 58-60, indicating the "constant TAS"
limit is generally very conservative, but it's best to stick to the
flight manual or contact the manufacturer for guidance.

The flight manual for my ASH 26 E uses a combination of constant IAS and
constant TAS for Vne: it's constant IAS up to 10,000', and essentially
constant TAS above that. That TAS value is equal to Vne (IAS) at 10,000'.

I recommend the "Fundamentals..." book be on every glider pilot's
bookshelf, and that the pilot read it through at least once. It's a
great resource, and a better place to start than wading through a bunch
of hits by Google.

--
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" atwww.motorglider.org

http://711reporting.blogspot.com/

# 711.

...So what to do?...

I think that falls under the four-Cs rule.

Bob K.

On Dec 30, 10:03*pm, "
wrote:
Hi Gang
* Last week Minden had some excellent wave soaring. Off tow at 7.7k
msl and within minutes up to 18k. I decided to go up north skirting
Reno Intl. I had the transponder on and was monitoring Reno Approach.
My goal was to try and fly as fast as possible maintaining an altitude
very close to 18k by speeding up in lift and slowing down in light
lift or sink. This worked well for the first 35 miles where my IAS
(indicated air speed) *ranged between 50 knots and 110 knots flying
never less than 17k. Then I got into some real lift and pointed the
nose down and noticed my Becker transponder registering 18.2k which
is, of course, a no no. I then glanced at the IAS. It read 138 knots
which is 165 knots TAS. (Every 1000 feet of altitude above sea level
results in an error of 1.5% in IAS.) So what to do? If I pulled the
spoilers at that speed, the shock might destroy them or the glider. So
I gently pulled the stick back and translated speed into altitude
going above 19k. At about 70 knots I pulled the spoilers and got
myself down to below 18k. I wonder if ATC caught that? Why was this so
bad? Well the VNE at sea level for the SparrowHawk is 123 knots and it
has been demonstrated that at 171 knots the wings come off. This
really gave me cause for concern. How quickly one can get into trouble
by not paying attention. In the future I will fly slower and use the
spoilers to compensate for excessive lift so as to maintain altitude.
* This story raises some questions about VNE at various altitudes
which should be of interest to all of us glider pilots. I Googled
combinations of words such as "flutter altitude", "VNE altitude" and
"aircraft breakup altitude" to try and come up with information on
whether the flutter/breakup characteristics of an aircraft are less at
altitude than sea level at the same TAS. Intuitively it would seem so
but intuition may not work here. I found nothing useful. I know that
the World's ultimate high altitude motor glider the U2, which was
designed in the 50s, had much study done on it with regard to its
operating speed window of about 20mph (stall to breakup)at 80k feet
msl. There should now be declassified documents on those studies which
might answer my questions. I would appreciate any pointers anyone. If
I find anything useful I will summarize it on RAS.
* Flying is often unforgiving of errors and I will definitely be more
vigilant after this wake up call.
Dave

Should have rolled her inverted and pulled hard

On a more serious note.
Attention to the altlimeter when wave flying so close to class A is
imperative.
That and looking out for the Southwest jet about to run you down on
the Reno south approach.
As you had a transponder that is not the main issue here.

Your lesson was learnt I guess so don't do it again.

I had a similar over speed experience once in my SZD59.
I was doing Acro in the wave and after about 45mins made myself pretty
sick pulling G's...
So to chill out I just soared in the nice smooth wave lift.
I climb from about 10K up to 17K whilst regaining my composure for
another acro session.

By now I was feeling better I turn upside down and start flying along
inverted.
Bored with inverted straight and level I thought "I know lets try an
inverted circle"
Initiating the bank and still at around 17K I suddenly have that panic
feeling of "I cant push the stick far enough forward to stop the dive"
As the glider accelerated very quickly in the thin air if I pulled
through it would have broken the plane up.
My only way out was to roll upright and pull G's.

As I start my roll out the ASI is up around 170knots!!
I am rolling and starting to get the nose above the horizon now.
The pull out pulled 6.5G's and gave me tunnel vision during the pull
out.

It is a VERY strong and well balanced plane that SZD59.

That was the scariest moment I ever had in my soaring career!!

Happy New Year everyone

Regards

Al

What does your POH say about opening spoilers at high speed? Below
Maneuvering Speed (80 kts, I checked) it shouldn't be a big deal.
FWIW, I think you did the right thing in losing speed right now, rather
than thinking of the FAA implications. Could the feds ground you from
flying your ultralight anyway (probably)? ;-)

Forgive me if this strays from the thread a little, but I think it is
worth expanding on the relationships between maneuvering speed (Va),
spoilers and speeds/loads. Here is my understanding:

1. There is no relationship between Va (maneuvering speed) and
spoilers, except that Va is determined with spoilers retracted. Va is
based on pitch (elevator inputs). There is a general belief that
below Va you can do anything with any flight control, and the glider
cannot be damaged. This is may be true in some, perhaps many,
situations, but it is not true in any certification sense. [See EASA
glider regs CS 22.335]

2. Once spoilers are deployed, the loads for which the glider is
certified drop to +3.5 from +5.3 (utility) / +7.0 (aerobatic). [See
EASA glider regs CS 22.345]

For the reason stated in #2 above, "The Handbook of Glider
Aerobatics" (Mallinson and Woollard, 1999, page 30) states "It is
nearly always better to slow a glider by 'pulling g' rather than by
operating the airbrakes". They are speaking here of aerobatic gliders
(rated to 7 g's) during aerobatic maneuvers. There is some difference
in the loads/slowing that can be achieved by utility gliders. Also,
there are other considerations when using 'g' to slow (symmetric
loads, etc.). For the purposes of this discussion, I think I'm safe
with the summarization that the choice of spoiler over 'g' should not
be automatic in all situations.

This is not to say that spoilers may or may not have been an
appropriate response in the case being discussed, or many other
situations. Rather, I want to dissuade those who might feel that
spoilers are an appropriate response in every situation. Certainly
deploying spoilers and pulling high g's could be a catastrophic
combination.

I am certainly open to correction if there is an error in my analysis.

Regards,
Eric

John Smith (is that really your name?) wrote:

I've read further down that you flew a Sparrowhawk which I don't know.
But every glider I do know (all of them JAR certified European gliders)
allow for spoiler operation up to Vne. Sure, if you just yank those
spoilers fully open at Vne, you *will* break or at least bend something,
but if you hold the handle with a firm grip and operate them carefully,
then you're perfectly fine. After all, those spoilers are *designed* to
limit the dive speed at Vne! Of course, verify this with your POH first.



The times that spoilers were designed to limit speed to vne in a
vertical dive are long gone. One of the last gliders certified that
way was the Open Cirrus which I had an opportunity to test in that
configuration when diving through a hole in the clouds on a rare wave
day in Northern Germany many years ago. It never went past 200 km/h.
Certification requirements were changed later to allow for only top-
deploying spoilers that I wouldn't want to try on a dive-bombing run.

Herb Kilian, J7

I apologize in advance:

Do the rest of you think 'violin' is fiddling the numbers?
grin

HAPPY NEW YEAR

At 14:54 01 January 2008, wrote:
What does your POH say about opening spoilers at high
speed? Below
Maneuvering Speed (80 kts, I checked) it shouldn't
be a big deal.
FWIW, I think you did the right thing in losing speed
right now, rather
than thinking of the FAA implications. Could the
feds ground you from
flying your ultralight anyway (probably)? ;-)

Forgive me if this strays from the thread a little,
but I think it is
worth expanding on the relationships between maneuvering
speed (Va),
spoilers and speeds/loads. Here is my understanding:

1. There is no relationship between Va (maneuvering
speed) and
spoilers, except that Va is determined with spoilers
retracted. Va is
based on pitch (elevator inputs). There is a general
belief that
below Va you can do anything with any flight control,
and the glider
cannot be damaged. This is may be true in some, perhaps
many,
situations, but it is not true in any certification
sense. [See EASA
glider regs CS 22.335]

2. Once spoilers are deployed, the loads for which
the glider is
certified drop to +3.5 from +5.3 (utility) / +7.0 (aerobatic).
[See
EASA glider regs CS 22.345]

For the reason stated in #2 above, 'The Handbook of
Glider
Aerobatics' (Mallinson and Woollard, 1999, page 30)
states 'It is
nearly always better to slow a glider by 'pulling g'
rather than by
operating the airbrakes'. They are speaking here of
aerobatic gliders
(rated to 7 g's) during aerobatic maneuvers. There
is some difference
in the loads/slowing that can be achieved by utility
gliders. Also,
there are other considerations when using 'g' to slow
(symmetric
loads, etc.). For the purposes of this discussion,
I think I'm safe
with the summarization that the choice of spoiler over
'g' should not
be automatic in all situations.

This is not to say that spoilers may or may not have
been an
appropriate response in the case being discussed, or
many other
situations. Rather, I want to dissuade those who might
feel that
spoilers are an appropriate response in every situation.
Certainly
deploying spoilers and pulling high g's could be a
catastrophic
combination.

I am certainly open to correction if there is an error
in my analysis.

Regards,
Eric

Herb wrote:

The times that spoilers were designed to limit speed to vne in a
vertical dive are long gone.

Where did I say vertical dive? JAR asks for a 30 degrees dive, or 45
degrees if certified for aerobatics or cloud flying. Nevertheless, the
spoilers are designed to hold the speed below Vne in the discribed
situation and can be used up to that speed.

On Dec 30 2007, 10:03*pm, "
wrote:
Hi Gang
* Last week Minden had some excellent wave soaring. Off tow at 7.7k
msl and within minutes up to 18k. I decided to go up north skirting
Reno Intl. I had the transponder on and was monitoring Reno Approach.
My goal was to try and fly as fast as possible maintaining an altitude
very close to 18k by speeding up in lift and slowing down in light
lift or sink. This worked well for the first 35 miles where my IAS
(indicated air speed) *ranged between 50 knots and 110 knots flying
never less than 17k. Then I got into some real lift and pointed the
nose down and noticed my Becker transponder registering 18.2k which
is, of course, a no no. I then glanced at the IAS. It read 138 knots
which is 165 knots TAS. (Every 1000 feet of altitude above sea level
results in an error of 1.5% in IAS.) So what to do? If I pulled the
spoilers at that speed, the shock might destroy them or the glider. So
I gently pulled the stick back and translated speed into altitude
going above 19k. At about 70 knots I pulled the spoilers and got
myself down to below 18k. I wonder if ATC caught that? Why was this so
bad? Well the VNE at sea level for the SparrowHawk is 123 knots and it
has been demonstrated that at 171 knots the wings come off. This
really gave me cause for concern. How quickly one can get into trouble
by not paying attention. In the future I will fly slower and use the
spoilers to compensate for excessive lift so as to maintain altitude.
* This story raises some questions about VNE at various altitudes
which should be of interest to all of us glider pilots. I Googled
combinations of words such as "flutter altitude", "VNE altitude" and
"aircraft breakup altitude" to try and come up with information on
whether the flutter/breakup characteristics of an aircraft are less at
altitude than sea level at the same TAS. Intuitively it would seem so
but intuition may not work here. I found nothing useful. I know that
the World's ultimate high altitude motor glider the U2, which was
designed in the 50s, had much study done on it with regard to its
operating speed window of about 20mph (stall to breakup)at 80k feet
msl. There should now be declassified documents on those studies which
might answer my questions. I would appreciate any pointers anyone. If
I find anything useful I will summarize it on RAS.
* Flying is often unforgiving of errors and I will definitely be more
vigilant after this wake up call.
Dave

I am very surprised that no one here, let alone yourself, thought of
the obvious: contact Reno Approach and advise them of your situation.
That would have alerted them to check for any possible conflicts and
clear the area around you of other traffic until you could get clear
of Class A airspace. You were negligent - and in violation of FARs -
by not doing this. Reno could have easily cleared you into Class A
until you could take appropriate actions. We ARE allowed to violate
FARs in an emergency, but this does not relieve you of your
responsibility to minimize the violation to the extent possible.
Fortunately, you were carrying a transponder...

Tom Seim