Thinking about stalls

On Mar 14, 9:11*am, Brian wrote:


As for your question above, given that the airplanes are ascending or
decending at constant rates then the lift is equal to the wieght of
the airplane in both cases. If the aircraft are the same wieght then
the lift generated will be the same.


That is not correct.

Cheers

WingFlaps wrote:
On Mar 14, 9:11*am, Brian wrote:
As for your question above, given that the airplanes are ascending or
decending at constant rates then the lift is equal to the wieght of
the airplane in both cases. If the aircraft are the same wieght then
the lift generated will be the same.


That is not correct.

Hmmm. Brian's statement appears essentially correct - and you are correct
too. The "gotcha" is that the vertical component of the lift force exceeds
the weight only during the transition from level flight to constant
ascending flight. And the lift force is less than the weight during the
transition from level flight to constant descending flight.

But once the vertical speed becomes constant (whether up or down) the
vertical component of lift has to equal the downward force of gravity. If
it didn't, then the aircraft would begin _accelerating_ up or down,
depending on the difference.

On Mar 12, 7:14*pm, WingFlaps wrote:
Hi All,

Imagine a plane in 2 conditions.

1) Climbing with full power
2) Descending fast with 50% power.

Both have constant rates of ascent and descent.

Question A: Which wing is closer to stall?
Question B: A big updraft occurs, which is more likely to stall?

If you vote first it _may_ lead to some good discussion later...

Cheers

It would depend on the angle of attack. You could be in a very
shallow climb at full power, and have lots of margin above the stall.
On the other hand, you could be descending at 50% power in a very nose-
high attitude, and have very little margin above the stall. Plus,
there's the cost of the hamburger you are flying towards.

Phil

On Wed, 12 Mar 2008 17:14:17 -0700 (PDT), WingFlaps
wrote:

Hi All,

Imagine a plane in 2 conditions.

1) Climbing with full power
2) Descending fast with 50% power.

Both have constant rates of ascent and descent.

Question A: Which wing is closer to stall?
Question B: A big updraft occurs, which is more likely to stall?

If you vote first it _may_ lead to some good discussion later...

Cheers

***************************************
Obviously #2. Any one should be able to see that.

Big John

On Mar 13, 6:45*pm, Big John wrote:
On Wed, 12 Mar 2008 17:14:17 -0700 (PDT), WingFlaps





wrote:
Hi All,

Imagine a plane in 2 conditions.

1) Climbing with full power
2) Descending fast with 50% power.

Both have constant rates of ascent and descent.

Question A: Which wing is closer to stall?
Question B: A big updraft occurs, which is more likely to stall?

If you vote first it _may_ lead to some good discussion later...

Cheers

***************************************
Obviously #2. Any one should be able to see that.


Aha, so it is closer to the stall?

Cheers

"WingFlaps" wrote in message
...
Hi All,

Imagine a plane in 2 conditions.

1) Climbing with full power
2) Descending fast with 50% power.

Both have constant rates of ascent and descent.

Question A: Which wing is closer to stall?
Question B: A big updraft occurs, which is more likely to stall?


I'm not sure if there's enough information. If it's a typical prop plant I
would expect that there would be a difference between a high wing and a low
wing due to slipstream effects, but my guess would be that the right wing
would be closer. Or, are you asking which of the two scenarios is
closer/more likely to stall. In that case, I'd say the first
configuration. Full-power departure stalls are easy to encounter.

-c

On Mar 14, 4:02*am, "gatt" wrote:
"WingFlaps" wrote in message

...

Hi All,

Imagine a plane in 2 conditions.

1) Climbing with full power
2) Descending fast with 50% power.

Both have constant rates of ascent and descent.

Question A: Which wing is closer to stall?
Question B: A big updraft occurs, which is more likely to stall?

I'm not sure if there's enough information. *If it's a typical prop plant I
would expect that there would be a difference between a high wing and a low
wing due to slipstream effects, but my guess would be that the right wing
would be closer. * Or, are you asking which of the two scenarios is
closer/more likely to stall. * *In that case, I'd say the first
configuration. * *Full-power departure stalls are easy to encounter.


Ok good, but let's say both planes have the same airspeed. Does that
change anything?
Cheers

Put me in the "not enough info" column.

Plane #2 could be in fact _in_ a stall (or spin), "descending fast
with 50% power" or _more_. Think Delta Flight 191, for example.



On Mar 12, 8:14 pm, WingFlaps wrote:
Hi All,

Imagine a plane in 2 conditions.

1) Climbing with full power
2) Descending fast with 50% power.

Both have constant rates of ascent and descent.

Question A: Which wing is closer to stall?
Question B: A big updraft occurs, which is more likely to stall?

If you vote first it _may_ lead to some good discussion later...

Cheers

TakeFlight wrote in news:935d6394-8224-482e-9428-
:

Put me in the "not enough info" column.

Plane #2 could be in fact _in_ a stall (or spin), "descending fast
with 50% power" or _more_. Think Delta Flight 191, for example.


That was something else entirely. That was a microburst. The rules pretty
much go out the window with one of those.
not to say the laws of physics are suspended, but it's a scenario that is
so different from what we learn as pilots that drastic retraining was
introduced right across the board after it. Flight guidance systems were
modified to account for the new methods, so it's not really relevant.

Just to give you some idea of what I mean, I'll give you a scenario. You've
just aken off and yoou're climibing away at best rate. Suddenly, your
airspeed increases by a fairly large lump. 15-20 knots, say. you increase
your pitcha bit to absorb it and your speed bleeds back a tad. Still plenty
in hand, though. all the sudden the pitch you have is dragging your speed
back and it's beginning to decrease as the wind that delivered that extra
speed vanishes. You're still OK and back to your orignal pitch and have a
couple of knots more than you had at the beginning. All the sudden, the
bottom falls out of your airplane. Your climb stops and then a second later
you begin to sink, and fast. another second or two and your speed washes
off even further and now you're sinkng and your stall warning is starting
to squeak.

you gotta do something and right now. you still have some altitude, say 400
feet. what do you do?



Bertie

On Mar 14, 11:37*am, Bertie the Bunyip wrote:
TakeFlight wrote in news:935d6394-8224-482e-9428-
:

Put me in the "not enough info" column.

Plane #2 could be in fact _in_ a stall (or spin), "descending fast
with 50% power" or _more_. *Think Delta Flight 191, for example.

That was something else entirely. That was a microburst. The rules pretty
much go out the window with one of those.
not to say the laws of physics are suspended, but it's a scenario that is
so different from what we learn as pilots that drastic retraining was *
introduced right across the board after it. Flight guidance systems were
modified to account for the new methods, so it's not really relevant.

Just to give you some idea of what I mean, I'll give you a scenario. You've
just aken off and yoou're climibing away at best rate. Suddenly, your
airspeed increases by a fairly large lump. 15-20 knots, say. you increase
your pitcha bit to absorb it and your speed bleeds back a tad. Still plenty
in hand, though. all the sudden the pitch you have is dragging your speed
back and it's beginning to decrease as the wind that delivered that extra
speed vanishes. You're still OK and back to your orignal pitch and have a
couple of knots more than you had at the beginning. All the sudden, the
bottom falls out of your airplane. Your climb stops and then a second later *
you begin to sink, and fast. another second or two and your speed washes
off even further and now you're sinkng and your stall warning is starting
to squeak.

you gotta do something and right now. you still have some altitude, say 400
feet. what do you do?

Bertie

Alt-Ctl-Del

No, wait, change my underwear.

Yoke forward, nose down and max power?

Richard