Newbie seeking advice

Exactly, I couldn't agree more, the parachute may save you in many different
situations.
Most of them are not the reason we are required to wear them, otherwise,
power pilots and passengers would be required to wear one too.

BTW, I've never heard of anything like this before with a glass ship :
an elevator folding gracefully onto the fin...

I've flown in front of CBs most of my flying career and never once had to
fly outside the envelope.
But that aside... an elevator folding ?? it probably was damaged before and
not well repaired.

Has this accident been listed anywhere on the Web so that we could all look
at it ?

"Bruce Greeff" wrote in message
...
(................................)
Pilots make mistakes, one of the most experienced pilots I have known
wrecked a
Ventus A by getting too close to a CB. He used full airbrake,
undercarriage out
and nose progressively steeper. Eventually the elevator folded gracefully
onto
the fin. (...................................)

Gldcomp wrote:
Maybe I need to clarify this in other words.
No legislative requirement was ever established to carry parachutes
because
airplanes or gliders fall appart in normal flight.
This is a common beginner's instinctive fear, expecially during a
recovery
from stall, that the wings will fold and they will drop down like a
rock.
Some people get so stressed out and terrorized by the sensation of G's
that
they will forever avoid more than 30 degrees of bank so they don't have
to
tackle the Gs. There are a lot of pilots like that.
The simple truth is that airplanes and gliders don't do that, UNLESS WE
FLY
OUTSIDE THE ENVELOPE (exceed VNE, G-loads, etc), or we sabotage it in
some
other fashion such as an ill-executed repair, or controls not properly
connected upon assembly.

I never said one is more survivable than the other.
Notice again what I said : Structural failures is NOT the reason we are
required to wear parachutes (but of course, if they do occur, parachutes
will save the pilot just as well).

Midair Collision is the reason we are required to wear parachutes.
That's all I said.

Gldcomp wrote:
Exactly, I couldn't agree more, the parachute may save you in many different
situations.
Most of them are not the reason we are required to wear them, otherwise,
power pilots and passengers would be required to wear one too.

BTW, I've never heard of anything like this before with a glass ship :
an elevator folding gracefully onto the fin...

I've flown in front of CBs most of my flying career and never once had to
fly outside the envelope.
But that aside... an elevator folding ?? it probably was damaged before and
not well repaired.

Big snip

By his own admission he was so far past Vne I don't think it appropriate to
consider structural defect. The aircraft was virtually new as I understand it -
and a new design at the time. (so the crash was not reported on the internet.)

The failure mode of most elevators at speeds exceeding Vne will be downwards.

Why he flew close enough to a CB that he was unable to avoid it while remaining
inside the envelope is anybodies guess.

That doesn't make sense to me. At high speeds, the elevator produces lift so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"


"Bruce Greeff" a écrit dans le message de
...

The failure mode of most elevators at speeds exceeding Vne will be
downwards.

"Bert Willing" wrote in
message ...
That doesn't make sense to me. At high speeds, the elevator produces lift
so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"

Bert,

The elevator does produce lift, but in the opposite direction as the wings
(most of the time anyway).

You're right - the elevator produces lift (same direction as the wings) at
low speeds, not at high speeds. Got mixed up.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
om...
"Bert Willing" wrote in
message ...
That doesn't make sense to me. At high speeds, the elevator produces
lift
so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"

Bert,

The elevator does produce lift, but in the opposite direction as the wings
(most of the time anyway).

Bert,

It has little to do with airspeed. The position of the CG will determine the
force on the elevator.


"Bert Willing" wrote in
message ...
You're right - the elevator produces lift (same direction as the wings) at
low speeds, not at high speeds. Got mixed up.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
om...
"Bert Willing" wrote in
message ...
That doesn't make sense to me. At high speeds, the elevator produces
lift
so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"

Bert,

The elevator does produce lift, but in the opposite direction as the
wings
(most of the time anyway).

Not quite correct. At high angles of attack, the elevator produces lift and
at of angle of attack, it produces negative lift. The crossover (i.e. zero
lift, minimum drag) is a design criterium and is usually placed at the max
L/D angle of attack. But then, this will of course be influenced by a large
variation of the CG.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
. com...
Bert,

It has little to do with airspeed. The position of the CG will determine
the
force on the elevator.


"Bert Willing" wrote in
message ...
You're right - the elevator produces lift (same direction as the wings)
at
low speeds, not at high speeds. Got mixed up.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
om...
"Bert Willing" wrote
in
message ...
That doesn't make sense to me. At high speeds, the elevator produces
lift
so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"

Bert,

The elevator does produce lift, but in the opposite direction as the
wings
(most of the time anyway).

"Bert Willing" wrote in message ...
You're right - the elevator produces lift (same direction as the wings) at
low speeds, not at high speeds. Got mixed up.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
om...
"Bert Willing" wrote in
message ...
That doesn't make sense to me. At high speeds, the elevator produces
lift
so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"

Bert,

The elevator does produce lift, but in the opposite direction as the wings
(most of the time anyway).



Ok, so let me see if I've got this straight now. I cruising along at
60 kts in trim and elevator close to neutral. I want to go 140kts so
I push the stick forward, the elevator goes down, which pushes the
tail up, which pushes the nose goes down, I go faster. And all this is
because the elevator is producing more lift in the downward direction?

For a fixed stab with moving elevator don't we have to consider the
forces on both components separately to predict the failure mode?


Andy

Andy Durbin wrote:
"Bert Willing" wrote
in message ...
You're right - the elevator produces lift (same direction as the
wings) at low speeds, not at high speeds. Got mixed up.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
om...
"Bert Willing"
wrote in message ...
That doesn't make sense to me. At high speeds, the elevator
produces
lift
so
in case of structural failure, the bits would go upwards.

--
Bert Willing

ASW20 "TW"

Bert,

The elevator does produce lift, but in the opposite direction as
the wings (most of the time anyway).



Ok, so let me see if I've got this straight now. I cruising along
at
60 kts in trim and elevator close to neutral. I want to go 140kts
so
I push the stick forward, the elevator goes down, which pushes the
tail up, which pushes the nose goes down, I go faster. And all this
is
because the elevator is producing more lift in the downward
direction?

For a fixed stab with moving elevator don't we have to consider the
forces on both components separately to predict the failure mode?

I think we are confusing transient and steady forces here. The
overspeed problem occurs with the controls almost in neutral, but the
plane in a dive, where the speed builds up steadily. In this case the
tailplane will be generating an increasing downward force in relation
to the longitudinal axis of the aircraft. This downward force is to
counteract the forward rotation force generated by the wing. At a high
enough speed these forces will increase beyond the capacity of the
structure to support them.

The transient case is when a large control excursion is input at high
speed, and in this case the force on the tailplane could be in either
direction, depending on the direction of control input. However
downward total force is likely to be more severe in a pull-up than an
upward force in a push-over, since the contribution of the elevator
adds to the existing downward force in the first case and subtracts
from it in the push-over case.

That's my 2c worth...
Cheers, John G.

Andy Durbin wrote:

The elevator does produce lift, but in the opposite direction as the wings
(most of the time anyway).




Ok, so let me see if I've got this straight now. I cruising along at
60 kts in trim and elevator close to neutral. I want to go 140kts so
I push the stick forward, the elevator goes down, which pushes the
tail up, which pushes the nose goes down, I go faster. And all this is
because the elevator is producing more lift in the downward direction?

It is confusing! Here's what happens, simplified:

*The horizontal stabilizer (with the flap we call the "elevator") is
pushing down (at least at "higher" speeds - maybe not at 60 knots -
dependes on the glider)
*You push the stick forward
*the elevator flap goes down
*this _reduces_ the downward force of the horizontal stabilizer, but
doesn't elimanate it
*this allows the tail to rise

There is more to it than that, of course.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA