Nimbus 4DT accident 31 July 2000 in Spain.

A careful read of the Minden accident report will reveal what two very
experinced pilots did. The owner P1 was a famous glider pilot, and P2 was a
WW II trained Naval Aviator, also famous. Eyewitness reports (in the NTSB
report) stated that the rotation had stopped, the glider nosed down, then
the wings bent up to about 45 deg, then failed. The spoilers were found
actuated. The wings broke just outboard of the spoiler. The report refers to
an interconnction between the flaps and the spoiler, full spoiler also
produces full flap. The report also states time for the glider to accelerate
to Vne and Vd, indicating quite rapid acceration.

Further in the report it is indicated that the N4DM was certified by JAR
with exceptions for stall/spin behavior.

The implication is that the pilot(s) stopped the yaw, the glider dropped
it's nose and started accelerating as expected, and then at or above Vd,
spoilers were actuated, and the wings broke. Neither pilot got out.

The Spanish accident reports notes that the spoilers were found in the
locked position.

So, in summary, one pilot pulled the stick and broke the aircraft, and one
pilot pulled the spoilers and broke the aircraft. Faced with going through
Vd and breaking the aircraft, or trying to recover and breaking the
aircraft--maybe the best chioce is to jump while it's still intact?

--
Hartley Falbaum



"Robert William" wrote in message
...
At 02:06 24 June 2005, Andreas Maurer wrote:
On Thu, 23 Jun 2005 16:34:41 -0500, Bob Johnson
wrote:

Frankly spoken, pulling the stick back hard enough
to break off the
wings shows that the pilot was lacking the most basic
skills to fly
that bird.


well, possibly, but having got to the position where
you could either go through Vd or pull back what would
YOU do?

HL Falbaum wrote:

Further in the report it is indicated that the N4DM was certified by JAR
with exceptions for stall/spin behavior.

How so? You cannot get a glider certificated without adhering to all JAR
22 requirements.

So, in summary, one pilot pulled the stick and broke the aircraft, and one
pilot pulled the spoilers and broke the aircraft.

Wrong. Neither of the two would have done any damage. They broke the
glider by doing both things at the same time.

Stefan

Stefan writes
Wrong. Neither of the two would have done any damage. They broke the
glider by doing both things at the same time.

No. With the Spanish tragedy the pilots didn't open the airbrakes but
the P1 broke the wings by pulling back too hard. Presumably it wasn't
necessarily Vne that broke the wings but excessive load (pulling back
too hard in a panic) once past maximum maneuvouring speed? Given the
P1's self-confessed lack of currency in spin-training (paraphrased from
memory; "did it once twenty years ago and swore never again") is it fair
to say that without the panic from an unpractised situation the spin and
resulting dive recovery might not have broken the wings? Limiting your
spin recovery to just pulling back hard is going to have unfortunate
consequences which ever way it turns out. That said, it was a terrible
thing to happen and my heart really does go out to the pilot and his
family.

The Minden tragedy involved opened airbrakes which in turn contributed
to breaking the wing. Still from pulling back too hard, but in quite
different circumstances where "too hard" might not have been so apparent
because of the reduction in wing area and thus perceived wing-loading.
But had the airbrakes not been out the wing might have sustained the
load. Though Vne may then have been passed.

So it would seem the answer is to not open the airbrakes but respect the
yellow band on your ASI when loading the aircraft with g. Even if this
means passing through Vne?

Or, if you do open the airbrakes in a last ditch attempt to avoid
breaching Vne be even more respectful with the loading when pulling out
of the dive. But, between the devil and the deep blue sea you're better
off not having stepped out onto the gunwale in the first place


--
Bill Gribble
http://www.scapegoatsanon.demon.co.uk
- Learn from the mistakes of others.
- You won't live long enough to make all of them yourself.

Bill Gribble wrote:

But, between the devil and the deep blue sea you're better

JAR 22 requires that a glider can be recovered from a spin of at least 5
full turns (or the number at which the spin transfers to a spiral, if
that number is smaller) by applying the "standard procedure" and without
exceeding the load limits. Last I've heard there are a couple of Nimbi
4DT registered in Germany and other European countries. Which means they
are JAR certificated, hence...

Stefan

I would question the 99% but surely theproblem is that
the 1% tend to be spectacular, and stings a bit.

At 02:06 24 June 2005, Andreas Maurer wrote:
On 23 Jun 2005 21:27:25 GMT, Don Johnstone
wrote:


Now here's a question. Given the answer above why when
the wing drops at the start of a take off run (winch
or aero-tow) does everyone almost without exception
try and lift the downgoing wing with aileron?

.... because it works in 99 percent of the cases?


Bye
Andreas

At 22:24 23 June 2005, Ian Johnston wrote:

snip

OK, so how would you described the difference. How
far does the wing
have to drop before /you/ use spin recovery rather
than stall
recovery? I'm genuinely interested: it's not supposed
to be a trick question in any way.

Ian

Its not about how far the wing has dropped, its about
whether the glider has started to rotate about the
dropped wing.

A wing drop stall has a lot of roll, some pitch but
not much yaw so your first action is to unstall the
wings by moving the stick forward.

If you've been slow to intiate the recovery, the glider
will start to yaw/rotate around the dropped wing and
once this has happened, your first action should be
full opposite rudder.

Ed

Edward Lockhart writes
Its not about how far the wing has dropped, its about whether the
glider has started to rotate about the dropped wing.

I think //that's// the answer the question was looking for.

If you've been slow to intiate the recovery, the glider will start to
yaw/rotate around the dropped wing and once this has happened, your
first action should be full opposite rudder.

Or the nose drop self-corrects the stall and the glider develops into a
spiral dive, in which case centring the controls and kicking in a
boot-full of opposite rudder is only going to delay recovery in the face
of a now rapidly approaching Vne.

Despite knowing the difference, being practised and familiar with the
characteristics, recovery and differences of both, it's the prospect of
mistaking a spiral dive for a spin in the adrenaline rush of the moment
that actually still scares me, despite the fact that I quite enjoy being
upside down in a glider



--
Bill Gribble
http://www.scapegoatsanon.demon.co.uk
- Learn from the mistakes of others.
- You won't live long enough to make all of them yourself.

At 15:12 24 June 2005, Stefan wrote:
HL Falbaum wrote:

Further in the report it is indicated that the N4DM
was certified by JAR
with exceptions for stall/spin behavior.

How so? You cannot get a glider certificated without
adhering to all JAR
22 requirements.

So, in summary, one pilot pulled the stick and broke
the aircraft, and one
pilot pulled the spoilers and broke the aircraft.

Wrong. Neither of the two would have done any damage.
They broke the
glider by doing both things at the same time.

Stefan

No, in the accident in Spain which started this thread,
all evidence points to the brakes not being deployed,
at all.

Andrew Warbrick wrote:

No, in the accident in Spain which started this thread,
all evidence points to the brakes not being deployed,
at all.

Please read the thread before commenting. HLF, to whom I was responding,
was explicitely referring to the Minden accident.

Stefan

I agrre with most of this except the exceed VNe bit.
The damger from exceeding VNe is flutter and flutter
WILL break the aircraft. I think the last paragraph
is the only option.

The only time a pilot (test pilots excepted) is likely
to experience a spin in a big wing aeroplane is if
it happens accidentally. Non aerobatic means no deliberate
spinning (in the UK anyway) which means there is no
opportunity to practice. Makes prevention and early
recognition even more vital.

At 16:00 24 June 2005, Bill Gribble wrote:
Stefan writes
Wrong. Neither of the two would have done any damage.
They broke the
glider by doing both things at the same time.

No. With the Spanish tragedy the pilots didn't open
the airbrakes but
the P1 broke the wings by pulling back too hard. Presumably
it wasn't
necessarily Vne that broke the wings but excessive
load (pulling back
too hard in a panic) once past maximum maneuvouring
speed? Given the
P1's self-confessed lack of currency in spin-training
(paraphrased from
memory; 'did it once twenty years ago and swore never
again') is it fair
to say that without the panic from an unpractised situation
the spin and
resulting dive recovery might not have broken the wings?
Limiting your
spin recovery to just pulling back hard is going to
have unfortunate
consequences which ever way it turns out. That said,
it was a terrible
thing to happen and my heart really does go out to
the pilot and his
family.

The Minden tragedy involved opened airbrakes which
in turn contributed
to breaking the wing. Still from pulling back too hard,
but in quite
different circumstances where 'too hard' might not
have been so apparent
because of the reduction in wing area and thus perceived
wing-loading.
But had the airbrakes not been out the wing might have
sustained the
load. Though Vne may then have been passed.

So it would seem the answer is to not open the airbrakes
but respect the
yellow band on your ASI when loading the aircraft with
g. Even if this
means passing through Vne?

Or, if you do open the airbrakes in a last ditch attempt
to avoid
breaching Vne be even more respectful with the loading
when pulling out
of the dive. But, between the devil and the deep blue
sea you're better
off not having stepped out onto the gunwale in the
first place


--
Bill Gribble
http://www.scapegoatsanon.demon.co.uk
- Learn from the mistakes of others.
- You won't live long enough to make all of them yourself.