Overspeed Recovery question

If you inadvertently fly into the yellow range and kiss the red range, and you get into the high speed vibration, what is the best way to slow before the wings depart the glider. My sense is to reach for the spoilers and slowly extend to slow. Any opinions on that matter?

On Tuesday, February 10, 2015 at 9:58:58 PM UTC-5, wrote:
If you inadvertently fly into the yellow range and kiss the red range, and you get into the high speed vibration, what is the best way to slow before the wings depart the glider. My sense is to reach for the spoilers and slowly extend to slow. Any opinions on that matter?

Besides the tendency for the spoilers to suck out and then bend back on the wing?????.... no problem.

Dropping the gear, easy pull back on the stick, don't look too hard at the ASI, etc........

On 2/10/2015 7:58 PM, wrote:
If you inadvertently fly into the yellow range and kiss the red range, and
you get into the high speed vibration, what is the best way to slow before
the wings depart the glider. My sense is to reach for the spoilers and
slowly extend to slow. Any opinions on that matter?


Priority One: Undo what you last did to get yourself into that situation -
which as stated appears to have been too much forward stick. Assuming gravity
(and not your straps or "purely" centripetal force) is keeping your butt
pressed into the seat, get the stick back promptly, which will have the almost
immediate effect of reducing the rate of energy increase, and even better - if
you get the nose up high enough - reducing its accumulation.

Once you're happy with your energy-state, you can can consider doing "other
stuff"...dropping the gear (will mostly make noise), spoilers (if below their
max opening speed and you're physically/mentally prepared for a "Holy S&*%!"
experience if this is your first opening of them at any speed not fairly close
to your normal pattern entry opening speed); etc.

Priority Two: Throughout, keep your mental cool, rationally assess the effect
of everything you do before doing something else, and seriously consider
landing ASAP depending on the nature/seriousness of the vibration (which, of
course you really can't completely assess from inside a flying cockpit).

Priority Three: RTFM (if the ship has one; U.S. Exp. Amateur Built ships may
not have much of one, if any)!

Bob W.

P.S. Of course, RTFM is actually Priority One, but the question as-posed
precludes reasonably doing so. :-)

On Tuesday, February 10, 2015 at 9:04:26 PM UTC-7, Bob Whelan wrote:
On 2/10/2015 7:58 PM, wrote:
If you inadvertently fly into the yellow range and kiss the red range, and
you get into the high speed vibration, what is the best way to slow before
the wings depart the glider. My sense is to reach for the spoilers and
slowly extend to slow. Any opinions on that matter?


Priority One: Undo what you last did to get yourself into that situation -
which as stated appears to have been too much forward stick. Assuming gravity
(and not your straps or "purely" centripetal force) is keeping your butt
pressed into the seat, get the stick back promptly, which will have the almost
immediate effect of reducing the rate of energy increase, and even better - if
you get the nose up high enough - reducing its accumulation.

Once you're happy with your energy-state, you can can consider doing "other
stuff"...dropping the gear (will mostly make noise), spoilers (if below their
max opening speed and you're physically/mentally prepared for a "Holy S&*%!"
experience if this is your first opening of them at any speed not fairly close
to your normal pattern entry opening speed); etc.

Priority Two: Throughout, keep your mental cool, rationally assess the effect
of everything you do before doing something else, and seriously consider
landing ASAP depending on the nature/seriousness of the vibration (which, of
course you really can't completely assess from inside a flying cockpit).

Priority Three: RTFM (if the ship has one; U.S. Exp. Amateur Built ships may
not have much of one, if any)!

Bob W.

P.S. Of course, RTFM is actually Priority One, but the question as-posed
precludes reasonably doing so. :-)

I think the key point is smoothness on the controls.

If the ground is no factor, don't try to fix things too quickly. Ease back a tiny bit until the airspeed starts a slow downward trend then let that trend ease you out of the dive. If the wings are still on, they'll probably stay on as the airspeed bleeds off.

If the ground is an issue, aim to scare the crap out of the worms by using all the height you have left in a low G pull out. You want to just barely miss the earth. As the airspeed drops into the yellow arc, slowly add up to 1/3 of your up elevator travel and when it gets into the green arc you can pile on more G up to your gliders useful load factor but beware of a secondary accelerated stall.

I would not recommend spoilers at all especially if you are pulling G. They shift the spanwise lift distribution outboard increasing the bending stress on the wing spar. In a low pullout, spoilers increase the radius and the likelihood of hitting the ground.

At 02:58 11 February 2015, wrote:
If you inadvertently fly into the yellow range and kiss the red range,
and
=
you get into the high speed vibration, what is the best way to slow
before
=
the wings depart the glider. My sense is to reach for the spoilers and
slo=
wly extend to slow. Any opinions on that matter?

A very experienced test pilot once told me, and several others, that if you
were faced with exceeding VNE you should pull as hard as you can, even if
it means exceeding max G load, to reduce speed as soon as you can to below
VNE. Catastrophic structural failures due to excess G are very rare unless
there are other factors, catastrophic failures due to flutter are almost
inevitable.
There is no right answer, just a less wrong one and I would stress I have
not had the opportunity to test this.
One of the requirements on a Grob 103 post major inspection test flight was
to operate the spoilers at 70kts, having done this many times I would not
recommend the spoilers option.

How can you "inadvertently fly into the yellow range and kiss the red
range"? Sleeping at the helm? You have to have quite a nose down
attitude to get near the red line and it doesn't sneak up on you. It's
very noisy and pitch sensitive.

Don's advice below is excellent.


On 2/11/2015 3:20 AM, Don Johnstone wrote:
At 02:58 11 February 2015, wrote:
If you inadvertently fly into the yellow range and kiss the red range,
and
=
you get into the high speed vibration, what is the best way to slow
before
=
the wings depart the glider. My sense is to reach for the spoilers and
slo=
wly extend to slow. Any opinions on that matter?

A very experienced test pilot once told me, and several others, that if you
were faced with exceeding VNE you should pull as hard as you can, even if
it means exceeding max G load, to reduce speed as soon as you can to below
VNE. Catastrophic structural failures due to excess G are very rare unless
there are other factors, catastrophic failures due to flutter are almost
inevitable.
There is no right answer, just a less wrong one and I would stress I have
not had the opportunity to test this.
One of the requirements on a Grob 103 post major inspection test flight was
to operate the spoilers at 70kts, having done this many times I would not
recommend the spoilers option.


--
Dan Marotta

On Wednesday, February 11, 2015 at 8:10:30 AM UTC-7, Dan Marotta wrote:
How can you "inadvertently fly into the yellow range and kiss the
red range"?* Sleeping at the helm?* You have to have quite a nose
down attitude to get near the red line and it doesn't sneak up on
you.* It's very noisy and pitch sensitive.



Don's advice below is excellent.






On 2/11/2015 3:20 AM, Don Johnstone
wrote:



At 02:58 11 February 2015, wrote:


If you inadvertently fly into the yellow range and kiss the red range,


and


=
you get into the high speed vibration, what is the best way to slow


before


=
the wings depart the glider. My sense is to reach for the spoilers and
slo=
wly extend to slow. Any opinions on that matter?



A very experienced test pilot once told me, and several others, that if you
were faced with exceeding VNE you should pull as hard as you can, even if
it means exceeding max G load, to reduce speed as soon as you can to below
VNE. Catastrophic structural failures due to excess G are very rare unless
there are other factors, catastrophic failures due to flutter are almost
inevitable.
There is no right answer, just a less wrong one and I would stress I have
not had the opportunity to test this.
One of the requirements on a Grob 103 post major inspection test flight was
to operate the spoilers at 70kts, having done this many times I would not
recommend the spoilers option.






--

Dan Marotta

Easier than you might think when flying at altitude, I inadvertently did it in my HP16T while going through a FAI Start for a 300k triangle at 12000 feet on a hot summer day, I was indicating 15kts under Red line when I experienced a low frequency elevator flutter, A gentle pull back on the stick and it stopped, probably lasted less than a second but definitely got my attention. A few minutes with an E6B, showed that my True Airspeed was well over VNE.

Brian

On Wednesday, February 11, 2015 at 2:30:06 AM UTC-8, Don Johnstone wrote:
At 02:58 11 February 2015, wrote:
If you inadvertently fly into the yellow range and kiss the red range,
and
=
you get into the high speed vibration, what is the best way to slow
before
=
the wings depart the glider. My sense is to reach for the spoilers and
slo=
wly extend to slow. Any opinions on that matter?

A very experienced test pilot once told me, and several others, that if you
were faced with exceeding VNE you should pull as hard as you can, even if
it means exceeding max G load, to reduce speed as soon as you can to below
VNE. Catastrophic structural failures due to excess G are very rare unless
there are other factors, catastrophic failures due to flutter are almost
inevitable.
There is no right answer, just a less wrong one and I would stress I have
not had the opportunity to test this.
One of the requirements on a Grob 103 post major inspection test flight was
to operate the spoilers at 70kts, having done this many times I would not
recommend the spoilers option.

Since flutter is a dynamic phenomenon related to wing stiffness, I could make a theoretical argument that loading the wing would help. But I am not going to test it.

There are a lot of pilots flying up in the mountains where I fly that are unaware that just because the placard says 146 knots IAS or whatever, that is not true at FL180. On my glider, 146 knots IAS at 10,000 ft, 122 at 18,000, 76 at 42,000.

Well here is what I did. I was flying behind an ASW24 in my LS6. We were comparing how the two ships performed while doing some wing overs and other stuff to burn off some excess altitude. At the top of the last wing over, the pilot in front of me rolled it inverted and pulled it in to a Split S. Without thinking about it too much I repeated the Split S a few seconds later. The rapid advance of the ASI towards red line was impressive and relentless. I pulled back some, nothing much happened, I pulled back some more, nothing much happened, I pulled the stick back to the stop and started cursing at everyone involved in this stupid decision, and finally the nose came back to a normal distance below the horizon rather than its previous straight down orientation. Nothing broke, cracked, acted weird, or got bent, but when I conferred with the other pilot on the ground, we both decided that we were not going to do that again, and we both needed a beer before going home.

SF

On 2/11/2015 11:25 AM, SF wrote:
Well here is what I did...
Snip...
Without thinking about it too much I repeated the Split S a few seconds
later. The rapid advance of the ASI towards red line was impressive and
relentless.

Between this and JJ's recent "thunderstorm" thread, methinks we're seeing
evidence of winter in the northern hemisphere; contributors are willing to
share some survived sillinesses! That's a good thing, and I thank all for sharing.

I happened to read the original question posed in this thread ("If you
inadvertently fly into the yellow range and kiss the red range, and you get
into the high speed vibration, what is the best way to slow before the wings
depart the glider. My sense is to reach for the spoilers and slowly extend to
slow.") late in the PM before retiring to Zonkland, and will admit the
2nd/declarative sentence, and a personally compelling interest in soaring
safety, triggered a mental alarm bell. I'll elaborate on "Why?" shortly.

But first, even if the question is simply a cleverly designed attempt to
initiate a broad-in-scope discussion (as distinct from reflecting the O.P.'s
personal/presently-felt state of knowledge), it's a good one! The devil is
always in the details, and the details of gliders' load-bearing construction
commonly include structures composed of wood, steel tube and fabric, sheet
aluminum, 1st-generation fiberglass, and carbon fiber. Each has distinctly
different toleration to "high speed vibration"...which itself is a concept
worthy of lengthy definition, perhaps! Bottom line is these details may prove
to be compellingly important to Joe PIC, particularly in the time granted by
the structure to implement "the proper response." Arguably, 1st-generation
glass structures may simultaneously be most likely display to "high speed
vibration", and, to grant Joe PIC the greatest length of time to correct it
before something disastrous happens to the structure; wood and sheet metal may
be least generous with pre-failure time. Regardless of structure, "high speed
vibration" *will* get your attention...as well it should!

I could be reading way too much into original question/and "sense" of the
O.P., but here's why the sentence pair triggered an alarm bell. Is any reader
aware of any glider manufacturer's ship documentation that recommends as the
*first* corrective step for anything (other than pattern work, and perhaps,
tow-related height correction) to open the spoilers? Others have sensibly
noted several structural reasons that doing so at "too high a speed" may be
distinctly unwise, and I'm a fan of undoing first what caused the
problem...which in the case of high speed, certainly wasn't the spoilers.

So...no snark intended in my original reply. Anyone who finds themselves with
a case of "inadvertent imminent overspeed" surely had BETTER be alarmed, and,
have a sensible, pre-planned course of action ready for immediate implementation.

Good, thought-provoking scenario...

Bob W.

P.S. My own glider thunderstorm story involves the usual "made sense at the
time" rationales, resulted in a go-around initiated on short final from the
full-flap condition in an HP-14, in blinding rain and strong lift, in order to
avoid an overshoot into a tree lined mini-canyon/defile. It happened with
somewhere between 300 and 400 total hours...and served as "fair warning"
regarding thunderstorms...not that I should have needed - or been granted -
any. Even though I got away with it, I really should've landed out at the last
usable field 10 or so miles away. My most compelling rationale for continuing
was a really lousy trailer, though wanting to complete the contest task played
a part too. As I recall, only 4 or 5 of 30 did...and it wasn't the
thunderstorm over the field that put 'em on the ground!