Downdraft at 12,000 feet

"JGalban" wrote

Which is exactly where you'd expect to find a rotor from the wave
spilling over the mountain. Flying into a rotor is more than just your
average downdraft. If it's strong, you can expect serious pitch and
bank excursions. Simply put, the plane can easily be out of control.
Combine that with IMC and loss of control would probably not be far
behind.

From what I have read, entering a real rotor, one would be lucky to be spat
out with the wings still attached to the plane.

Loss of control? Certainly.

Loss of plane? Perhaps.

Thoughts? Some out here can discuss rotors with authority, I'm sure.

Jer ? ? ?
--
Jim in NC

"Morgans" wrote:
From what I have read, entering a real rotor, one would be lucky to be spat
out with the wings still attached to the plane.

Loss of control? Certainly.

Loss of plane? Perhaps.

Thoughts? Some out here can discuss rotors with authority, I'm sure.

Can't say with authority but no way will I go anywhere near a rotor.
High winds over the Rockies and I don't fly over the mountains.

I have experienced downdrafts and updrafts but nowhere near a rotor.

Ron Lee

Newps writes:

No certificated GA plane is unstable in roll.

This conflicts with other claims I've read in this group from time to
time, to the effect that all GA planes are unstable, IIRC.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Morgans schrieb:

From what I have read, entering a real rotor, one would be lucky to be spat
out with the wings still attached to the plane.

Thoughts? Some out here can discuss rotors with authority, I'm sure.

Glider pilots use rotors routinely as an elevator to the wave. At some
places, the tow plane tows them right into the rotor. (Formation flight
into the rotor.) So far, all wings still in place and everybody still
alive. Just make sure you stay well below vB.

Stefan

Recently, Mxsmanic posted:

Newps writes:

No certificated GA plane is unstable in roll.

This conflicts with other claims I've read in this group from time to
time, to the effect that all GA planes are unstable, IIRC.

Two different issues, I suspect. No planes are stable indefinitely, while
others are quite sensitive and will behave as described.

Neil

Newps,

No certificated GA plane is unstable in roll.


Define unstable.

--
Thomas Borchert (EDDH)

"Newps" wrote in message
. ..


Danny Deger wrote:


I used to own a 35 model Bonanza and it was unstable in roll and would
easily enter a "death spiral".


No certificated GA plane is unstable in roll.

I simply disagree. A GA plane, if put it a small roll can have the roll
increase if the pilot does nothing. The 35 model Bonanza is unstable in
roll. Go rent one and see for yourself. If you put it in a 30 degree bank
and let go of the stick, the roll will increase until you are in a death
spiral. That is why so many Bonanzas end up in one compared with other
airplanes. As far as I know, all Cessnas are stable in roll, i.e. without
pilot intervention they roll back to wings level.

I have a Masters in Aerospace engineering and my thesis was how to certify
light aircraft. The regs clearly state unstable in roll is acceptable.
They must be stable in pitch, but not in roll.

Danny Deger

"Thomas Borchert" wrote in message
...
Newps,

No certificated GA plane is unstable in roll.


Define unstable.


If the pilot does nothing, the disturbance (e.g. pitch or roll) will
increase.

Danny Deger

Morgans wrote:

"JGalban" wrote

Which is exactly where you'd expect to find a rotor from the wave
spilling over the mountain. Flying into a rotor is more than just your
average downdraft. If it's strong, you can expect serious pitch and
bank excursions. Simply put, the plane can easily be out of control.
Combine that with IMC and loss of control would probably not be far
behind.

From what I have read, entering a real rotor, one would be lucky to be spat
out with the wings still attached to the plane.

Loss of control? Certainly.

Loss of plane? Perhaps.

Thoughts? Some out here can discuss rotors with authority, I'm sure.

Jer ? ? ?

There are rotors, then there are ROTORS!

When the winds aloft, at mountain top altitude (~12,000), are
over 25 KN, the local winds are often over 50 KN because of
the effect of the wind flowing down the (constricted) valleys.

So, over 25 KN winds aloft, I choose to stay FAR away from the
rotors... and WATCH where the waves set-up, as the rotors
are under where the waves peak. Now, just because there is not
enough water in the air to see the wave does not mean that they
don't exist... just that you can not see them.

Winds aloft under 20 KN create a little wave, and some benign (read
FUN) rotors. I am often there in an airplane or glider, touching
the edge of the rotor (no visible moisture), to get lift or sink as
needed. A rotor may be relatively smooth, or VERY rough. It just
depends on the nature of the wind on that day and in that location.

I think it is fun to "go play in the wave" near Leadville, Colorado
and the Ten Mile Range. It is ideally set-up as relatively
north-south, and with a 20 KN wind from the west, it gives an
excellent training situation so that a pilot (with a qualified
mountain instructor on board) can experience the wave. We fly in
the lift, then over to the sink, then go touch the rotor and then
fly back to the lift. DO NOT TRY THIS ON YOUR OWN! I have enough
experience to know where the wave and the rotor are, and always have
several "outs" pre-planned in case I made an incorrect choice.


Best regards,

Jer/ "Flight instruction and mountain flying are my vocations!"
--
Jer/ (Slash) Eberhard, Mountain Flying Aviation, LTD, Ft Collins, CO
CELL 970 231-6325 EMAIL jer at frii.com http://users.frii.com/jer/
C-206 N9513G, CFII Airplane&Glider FAA-DEN Aviation Safety Counselor
CAP-CO Mission&Aircraft CheckPilot BM218 HAM N0FZD 247 Young Eagles!

"T o d d P a t t i s t" wrote in message
...
"Morgans" wrote:

From what I have read, entering a real rotor, one would be lucky to be
spat
out with the wings still attached to the plane.

Rotors can be strong or relatively mild. It's fairly common
to use rotors to climb into the mountain wave in a glider.
They can be extremely violent, but the stronger they are the
more likely that you can see them, or wave phenomenon near
them, and stay out of the worst part. A strong rotor is
associated with a strong wave which will have strong up and
down drafts that open a wave gap (the "Foehn gap") in solid
overcast near the rotor. It's not uncommon to climb through
that gap and see solid overcast everywhere except in the
gap. Moisture in the air will produce lenticular clouds
marking the position of the wave, and that gives another
clue to the wave/rotor position. Often, the rotor will be
marked by a rotating cloud in the core.

Loss of control? Certainly.

I've been rolled 90 degrees on tow, even though I was
expecting wave activity.

Loss of plane? Perhaps.

I think "perhaps" is correct, it has happened, but it's
extremely rare. Experienced glider pilots regularly seek
out strong wave activity, and experienced tow pilots
regularly tow gliders to the front (rising) edge of the
rotor. Commercial glider operations in Colorado have made a
business of drawing glider pilots from around the world to
fly in the waves of the Rockies. The trick is knowing where
the wave and rotor are.

Thoughts? Some out here can discuss rotors with authority, I'm sure.


All of this talk about rotors makes me glad I fly in Houston Texas with the
closest mountain hundreds of miles away.

Danny Deger