CFI oral intel

[gatt[_4_]]

One of the folks around the hangar took his CFI practical last week. He
had his AGI so they threw out all of the Fundamentals of Instruction
stuff entirely during the oral.

A question the examiner asked him: "You're flying cross-country and
trimmed at 110 knots. You die, and the engine quits. At what airspeed
will the aircraft strike the ground?"

Another was, "You're turning final and you enter a cross-control stall.
Is it better to be in a slip, or a skid?"

-c

[Gezellig]

On Thu, 29 May 2008 07:21:20 -0700, gatt wrote:

> One of the folks around the hangar took his CFI practical last week. He
> had his AGI so they threw out all of the Fundamentals of Instruction
> stuff entirely during the oral.
>
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?

That's easy, gatt. I wouldn't know.

Or care.

[gatt[_4_]]

Gezellig wrote:
> On Thu, 29 May 2008 07:21:20 -0700, gatt wrote:

>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> will the aircraft strike the ground?
>
> That's easy, gatt. I wouldn't know.
>
> Or care.

Ha! That was my thought: If I'm dead, what difference does it make?

[Bertie the Bunyip[_25_]]

gatt > wrote in
:

>
> One of the folks around the hangar took his CFI practical last week.
He
> had his AGI so they threw out all of the Fundamentals of Instruction
> stuff entirely during the oral.
>
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"


He's obviously looking at getting an answer that it will be the same
speed, but that's not correct. It probably wouldn;'t be far off it, but
the thrust line and any up or down thrust will play a big part in what
the airplane settles at after the engine dies.
>
> Another was, "You're turning final and you enter a cross-control
stall.
> Is it better to be in a slip, or a skid?"

If you're asking, Slip.



Bertie

[gatt[_4_]]

Bertie the Bunyip wrote:
> gatt > wrote in

>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> will the aircraft strike the ground?"
>
>
> He's obviously looking at getting an answer that it will be the same
> speed, but that's not correct. It probably wouldn;'t be far off it


The answer he apparently wanted was 110 knots, but I would have told him
-around- 110 knots.


>> Another was, "You're turning final and you enter a cross-control
> stall. Is it better to be in a slip, or a skid?"
>
> If you're asking, Slip.

That's what I'd have told him. (If you're in a 30-degree bank and your
outboard wing stalls you'll roll through wings-level but if your inboard
wing drops you're increasing your bank even further.)

I don't know what the examiner wanted to hear, but, that's the answer
I'd have given him.

-c

[Bertie the Bunyip[_25_]]

gatt > wrote in
:

> Bertie the Bunyip wrote:
>> gatt > wrote in
>
>>> A question the examiner asked him: "You're flying cross-country and
>>> trimmed at 110 knots. You die, and the engine quits. At what
airspeed
>>> will the aircraft strike the ground?"
>>
>>
>> He's obviously looking at getting an answer that it will be the same
>> speed, but that's not correct. It probably wouldn;'t be far off it
>
>
> The answer he apparently wanted was 110 knots, but I would have told
him
> -around- 110 knots.
>
>
>>> Another was, "You're turning final and you enter a cross-control
>> stall. Is it better to be in a slip, or a skid?"
>>
>> If you're asking, Slip.
>
> That's what I'd have told him. (If you're in a 30-degree bank and
your
> outboard wing stalls you'll roll through wings-level but if your
inboard
> wing drops you're increasing your bank even further.)
>
> I don't know what the examiner wanted to hear, but, that's the answer
> I'd have given him.
>
> -c
>

Well, you're much more likely to spin out of a skid than a slip is what
he was getting at..



Bertie

[Dudley Henriques[_2_]]

gatt wrote:

> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"
>
> Another was, "You're turning final and you enter a cross-control stall.
> Is it better to be in a slip, or a skid?"
>
> -c

These are reasonable questions.

The aircraft would attempt to regain and maintain the trim speed as it
descends. Whether or not it had the time to do that before ground impact
however would be dependent on the altitude remaining, so depending on
the altitude, the airspeed at impact might be short of the trim speed.

(This type of question is typical of FAA orals. They're looking for the
trim speed answer while completely neglecting the time and altitude
factors which to be accurate would have to be in the answer equation.

My advice to the person taking the oral would be to give the trim speed
answer, get the certificate, put it deep in the wallet and in your
pocket, then politely suggest to the fuzz that the altitude should be
included in the answer if not in the question itself :-)

A slipped cross control stall as relates to spin entry is FAR less
pro-spin than a skid entry.

--
Dudley Henriques

[Robert M. Gary]

On May 29, 7:21*am, gatt > wrote:
> One of the folks around the hangar took his CFI practical last week. *He
> had his AGI so they threw out all of the Fundamentals of Instruction
> stuff entirely during the oral.

Huh, that's not right. There is nothing in the PTS that says you get
to skip the FOI stuff just because you have an AGI. The only thing you
get to skip is showing your FOI exam results. I had my AGI and
probably spent 5 hours of my CFI oral on FOI stuff.

-Robert, CFII, AGI

[Robert M. Gary]

On May 29, 8:19*am, Dudley Henriques > wrote:
> gatt wrote:

> The aircraft would attempt to regain and maintain the trim speed as it
> descends. Whether or not it had the time to do that before ground impact
> however would be dependent on the altitude remaining, so depending on
> the altitude, the airspeed at impact might be short of the trim speed.

When I was a student pilot my instructor always said the plane will
seek its trim speed regardless of what you do with power settings.
I've actually never found that to be totally true in any plane I've
flown but it is grossly true.

-Robert

[Jim[_13_]]

On Thu, 29 May 2008 07:21:20 -0700, gatt
> wrote:

>
>One of the folks around the hangar took his CFI practical last week. He
>had his AGI so they threw out all of the Fundamentals of Instruction
>stuff entirely during the oral.
>
>A question the examiner asked him: "You're flying cross-country and
>trimmed at 110 knots. You die, and the engine quits. At what airspeed
>will the aircraft strike the ground?"
>
>Another was, "You're turning final and you enter a cross-control stall.
> Is it better to be in a slip, or a skid?"
>
>-c

Wow. I'm glad I have not been asked the first question. I think I
would have given an answer different from that given by the more
experienced folks here.

On the chance the plane went into a spiral dive, which I understand
can happen, I would have thought the plane would attempt to maintain
its trim AOA, but not its trim airspeed. I would likely have said the
plane would strike the ground -- if it had the necessary altitude, as
others have pointed out -- at approximately its trim AOA but at an
airspeed that might be a lot higher than its trim airspeed -- if the
wings did not come off before that.

Jim

[Jim Stewart]

gatt wrote:
>
> One of the folks around the hangar took his CFI practical last week. He
> had his AGI so they threw out all of the Fundamentals of Instruction
> stuff entirely during the oral.
>
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"
>
> Another was, "You're turning final and you enter a cross-control stall.
> Is it better to be in a slip, or a skid?"

I'm wondering what the significance of posting
this question is. Is it because everyone should
know the answer or because on some level it is
nonsensical?

BTW, my instructor covered the issue in-depth in
my pre-solo test. The gist of the discussion being
that a spin will develop much quicker in a skid since
the lower wing will drop, as opposed to a slip,
where the high wing has to drop, giving you more
time to recognize and break the stall.

[Michael[_1_]]

On May 29, 10:58*am, Bertie the Bunyip > wrote:
> He's obviously looking at getting an answer that it will be the same
> speed, but that's not correct. It probably wouldn;'t be far off it, but
> the thrust line and any up or down thrust will play a big part in what
> the airplane settles at after the engine dies.

And in a propeller-driven plane with a conventional (as opposed to a T-
tail) empennage, the design and location (relative to the prop blast)
of the horizontal stab will probably swamp the effect of the thrust
line. In most cases, the trim speed will actually be higher when the
engine quits.

This question is a good one - without more information it can't really
be answered, but it's a great jumping-off point for a discussion of
the way pitch, power, and speed interact.

The airplane CFI PTS includes demonstrating and explaining trim stalls
(I remember having to do one on my CFI-ASE ride). So at least the
people who wrote the PTS expected the CFI to have that level of
aerodynamic knowledge, as well they should. It would help him to
explain to the student why certain things happen, and what he should
expect.

But that's probably way beyond what the average ops inspector is going
for (and probably more than he knows) - and it's somewhat depressing
that it's obvious to us that he's going for the wrong answer. You
would think we would give the guy the benefit of the doubt - but
having met several ops inspectors, I find that difficult to do.

Michael

[gatt[_4_]]

Jim Stewart wrote:
> gatt wrote:

>> Another was, "You're turning final and you enter a cross-control
>> stall. Is it better to be in a slip, or a skid?"
>
> I'm wondering what the significance of posting this question is.

They're aviation forums. Some people still actually like to discuss
aviation out here.

>Is it because everyone should know the answer or because on some level it is
> nonsensical?

Actually, it's because if there are CFI candidates on the newsgroup it
might help them to understand what kinds of questions they can expect.


-c

[Jim Stewart]

gatt wrote:
> Jim Stewart wrote:
>> gatt wrote:
>
>>> Another was, "You're turning final and you enter a cross-control
>>> stall. Is it better to be in a slip, or a skid?"
>>
>> I'm wondering what the significance of posting this question is.
>
> They're aviation forums. Some people still actually like to discuss
> aviation out here.

I didn't mean to come off as a smart-ass. As
I said, my instructor and I covered this well
before I soloed. I assumed that every soloed
student would know the answer, let alone a CFI
candidate.

I guess I was wrong.

>> Is it because everyone should know the answer or because on some level
>> it is
>> nonsensical?
>
> Actually, it's because if there are CFI candidates on the newsgroup it
> might help them to understand what kinds of questions they can expect.
>
>
> -c

[gatt[_4_]]

Jim Stewart wrote:
> gatt wrote:
>> Jim Stewart wrote:

> I didn't mean to come off as a smart-ass. As I said, my instructor and I covered this well
> before I soloed. I assumed that every soloed student would know the answer, let alone a CFI
> candidate.
>
> I guess I was wrong.

Probably not. There's a brief discussion of it in the Airplane Flying
Handbook, Chapter 4, that relates to demonstrating a cross-control
stall. In terms of the CFI checkride, I suppose if you were going to
demonstrate one in a complex aircraft or to a pre-solo student you'd
want to do the one that won't result in an extreme bank or a spin.


-c

[Jim Logajan]

gatt > wrote:
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"

It all depends on what caused you to die. ;-)

(Actually I'm semi-serious, in spite of the wink.)

[Dudley Henriques[_2_]]

gatt wrote:
> Jim Stewart wrote:
>> gatt wrote:
>>> Jim Stewart wrote:
>
>> I didn't mean to come off as a smart-ass. As I said, my instructor
>> and I covered this well
>> before I soloed. I assumed that every soloed student would know the
>> answer, let alone a CFI
>> candidate.
>>
>> I guess I was wrong.
>
> Probably not. There's a brief discussion of it in the Airplane Flying
> Handbook, Chapter 4, that relates to demonstrating a cross-control
> stall. In terms of the CFI checkride, I suppose if you were going to
> demonstrate one in a complex aircraft or to a pre-solo student you'd
> want to do the one that won't result in an extreme bank or a spin.
>
>
> -c

I think I'm reading in what you are saying that it might be better for a
CFI to demonstrate a crossed control stall in the slip configuration
rather than the skid due to extreme bank or spin?

Just a few thoughts on this if I may.

In my opinion, thinking this way as a CFI is not the optimum way to go,
and might in fact prove a valuable missed opportunity to save a life
down the road.

With cross control stalls, you want to do more than simply demonstrate
(or prove if you wish) that an aircraft can be stalled in a cross
controlled condition. You want to leave a permanent impression on the
student about cross control stall and ALL it's ramifications.

This can be done safely in BOTH the slip and skid condition, and it
requires an instructor who is sharp in stall recovery which you should
be to begin with.

Of PARAMOUNT importance to the cross control demonstration is having the
student EXPERIENCE the DIFFERENCE between the two configurations as they
relate to recovery response from the wing drop. To do this, the
instructor should demonstrate BOTH stalls, emphasizing the aircraft
behavior in each configuration.
To shy away from the skid configuration because of an aversion to
extreme bank or spin, whether that be on the student's side or the
instructor's side of the equation in my opinion is wrong.

To achieve the optimum instructional benefit, the instructor should
first of all be COMPLETELY familiar with the stall behavior of the
aircraft being used. Different types have VERY different cross control
stall behavior and it's incumbent on every CFI to be completely
proficient in the cross control behavior of the type being used before
any cross control demonstration or instruction is done. Some high
performance singles have a very brisk stall break when cross controlled,
ESPECIALLY in skid!.
The method of instruction should be a thorough ground pre- brief with
the student on what will be done, addressing ny apprehension the student
might have. Then in the air, the student should follow through with the
instructor first through a slip stall, then in the skid stall.

What's important here is that the instructor should treat BOTH sides of
the demonstration as routine and as such, not to be feared IF UNDERSTOOD!

I also advocate letting the student do the stalls to both sides. If the
instructor can't control that situation, he/she shouldn't be in the
airplane teaching these stalls to begin with.

For the instructor, emphasis is on recovery technique requiring
immediate angle of attack reduction to break the stall IN COORDINATION
with immediate control application to break any roll onset. Although the
slip side stall can usually be broken before going past wings level,
there is absolutely no reason to fear the skid side. If proper recovery
is initiated from the skid side, there might be a faster break and a
deeper entry into roll that can exceed wings level, but if recovery is
done correctly, the stall can be broken and recovered without alarming a
properly prepared student.
The secret to all of this is PREPARING THE STUDENT, then presenting
these stalls in a calm,and totally routine manner.

I have never turned a student loose to aviation without teaching them
these all important stall recoveries.
--
Dudley Henriques

[gatt[_4_]]

Dudley Henriques wrote:

> Just a few thoughts on this if I may.
>
> In my opinion, thinking this way as a CFI is not the optimum way to go,
> and might in fact prove a valuable missed opportunity to save a life
> down the road.
>
> With cross control stalls, you want to do more than simply demonstrate
> (or prove if you wish) that an aircraft can be stalled in a cross
> controlled condition. You want to leave a permanent impression on the
> student about cross control stall and ALL it's ramifications.
>
> This can be done safely in BOTH the slip and skid condition, and it
> requires an instructor who is sharp in stall recovery which you should
> be to begin with.
>
> Of PARAMOUNT importance to the cross control demonstration is having the
> student EXPERIENCE the DIFFERENCE between the two configurations as they
> relate to recovery response from the wing drop. To do this, the
> instructor should demonstrate BOTH stalls, emphasizing the aircraft
> behavior in each configuration.
> To shy away from the skid configuration because of an aversion to
> extreme bank or spin, whether that be on the student's side or the
> instructor's side of the equation in my opinion is wrong.

....[snipped for brevity]

Another one for the archives. Thanks, Dudley.

I got the information about the question second-hand (the candidate told
the chief instructor who told me) so I'm not sure exactly what the
examiner as getting at. Now I'm really curious. It probably boils down
to the difference between a cross-control stall behavior in a slip
versus a skid. The FSDO examiners out here really hammer CFI candidates
on aerodynamics, or so I'm told, and less on the FOI if the candidate
appears reasonably capable of teaching. Seems appropriate enough.

-c

[Vaughn Simon]

"Bertie the Bunyip" > wrote in message
...
> gatt > wrote in
> :
> He's obviously looking at getting an answer that it will be the same
> speed, but that's not correct. It probably wouldn;'t be far off it, but
> the thrust line and any up or down thrust will play a big part in what
> the airplane settles at after the engine dies.

If it ever settles down. The process of losing the engine thrust will likely
trigger a phugoid oscillation, which may or may not dampen out before you reach
the ground. Your airspeed would depend on just where you happened to be in the
cycle when airframe meets ground.

Those of you who have never broken the monotony of a x-country by exploring
the phugoid characteristics of your steed have missed a good opportunity to
learn something about your airplane. (Don't forget to see how it differs with
CG.) BTW: Some gliders have rather exciting phugoids.

Vaughn

[Dudley Henriques[_2_]]

gatt wrote:


> Another one for the archives. Thanks, Dudley.
>
> I got the information about the question second-hand (the candidate told
> the chief instructor who told me) so I'm not sure exactly what the
> examiner as getting at. Now I'm really curious. It probably boils down
> to the difference between a cross-control stall behavior in a slip
> versus a skid. The FSDO examiners out here really hammer CFI candidates
> on aerodynamics, or so I'm told, and less on the FOI if the candidate
> appears reasonably capable of teaching. Seems appropriate enough.
>
> -c

You're welcome.

What they probably want is be assured that the CFI fully understands the
dangers involved with skidding turns, especially at low altitude.

To do it right, the CFI should use the necessity to impart this
information to discuss and teach cross controlled stall in ALL
configurations so that a BETTER understanding of the various
ramifications involved be more understood.
--
Dudley Henriques

[NW_Pilot]

"Gezellig" > wrote in message
...
> On Thu, 29 May 2008 07:21:20 -0700, gatt wrote:
>
>> One of the folks around the hangar took his CFI practical last week. He
>> had his AGI so they threw out all of the Fundamentals of Instruction
>> stuff entirely during the oral.
>>
>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> will the aircraft strike the ground?
>
> That's easy, gatt. I wouldn't know.
>
> Or care.

That summs it upp....

[NW_Pilot]

"Dudley Henriques" > wrote in message
...
> gatt wrote:
>
>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> will the aircraft strike the ground?"
>>
>> Another was, "You're turning final and you enter a cross-control stall.
>> Is it better to be in a slip, or a skid?"
>>
>> -c
>
> These are reasonable questions.
>
> The aircraft would attempt to regain and maintain the trim speed as it
> descends. Whether or not it had the time to do that before ground impact
> however would be dependent on the altitude remaining, so depending on the
> altitude, the airspeed at impact might be short of the trim speed.
>
> (This type of question is typical of FAA orals. They're looking for the
> trim speed answer while completely neglecting the time and altitude
> factors which to be accurate would have to be in the answer equation.
>
> My advice to the person taking the oral would be to give the trim speed
> answer, get the certificate, put it deep in the wallet and in your pocket,
> then politely suggest to the fuzz that the altitude should be included in
> the answer if not in the question itself :-)
>
> A slipped cross control stall as relates to spin entry is FAR less
> pro-spin than a skid entry.
>
> --
> Dudley Henriques

Also need to look at coprs position are you slumped over and placign fwd
control pressure on the yoke? is the auto pilot on? lots of questions....

[NW_Pilot]

"Robert M. Gary" > wrote in message
...
On May 29, 7:21 am, gatt > wrote:
> One of the folks around the hangar took his CFI practical last week. He
> had his AGI so they threw out all of the Fundamentals of Instruction
> stuff entirely during the oral.

Huh, that's not right. There is nothing in the PTS that says you get
to skip the FOI stuff just because you have an AGI. The only thing you
get to skip is showing your FOI exam results. I had my AGI and
probably spent 5 hours of my CFI oral on FOI stuff.

-Robert, CFII, AGI

FOI is my hangup right now....

[Jay Maynard]

On 2008-05-29, Vaughn Simon > wrote:
> Those of you who have never broken the monotony of a x-country by exploring
> the phugoid characteristics of your steed have missed a good opportunity to
> learn something about your airplane. (Don't forget to see how it differs with
> CG.) BTW: Some gliders have rather exciting phugoids.

Oh? Please enlighten me, since I'm going to ahve a sterling opportunity to
do so in the not very distant future.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (ordered 17 March, delivery 10 June)

[Michael Ash]

In rec.aviation.student gatt > wrote:
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"

In addition to all the other factors discussed, your airspeed will be
slightly lower than what you had trimmed due to the weight of your soul
departing the aircraft.

OK, so I don't really believe that, but I'd love to see what the guy would
say if you told him that answer!

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Gezellig[_2_]]

Dudley Henriques presented the following explanation :
> A slipped cross control stall as relates to spin entry is FAR less pro-spin
> than a skid entry.

Dudley, I don't understand why that is? Are you assuming 110 nauts?

[Gezellig[_2_]]

Jim formulated on Thursday :
>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> will the aircraft strike the ground?"
>>
>> Another was, "You're turning final and you enter a cross-control stall.
>> Is it better to be in a slip, or a skid?"
>>
>> -c

> Wow. I'm glad I have not been asked the first question. I think I
> would have given an answer different from that given by the more
> experienced folks here.

> On the chance the plane went into a spiral dive, which I understand
> can happen, I would have thought the plane would attempt to maintain
> its trim AOA, but not its trim airspeed. I would likely have said the
> plane would strike the ground -- if it had the necessary altitude, as
> others have pointed out -- at approximately its trim AOA but at an
> airspeed that might be a lot higher than its trim airspeed -- if the
> wings did not come off before that.

> Jim

Thanks, Jim, I am comforted with the fact that we share a common
dumminess here. lol

[Dudley Henriques[_2_]]

Gezellig wrote:
> Dudley Henriques presented the following explanation :
>> A slipped cross control stall as relates to spin entry is FAR less
>> pro-spin than a skid entry.
>
> Dudley, I don't understand why that is? Are you assuming 110 nauts?
>
>

Not sure what you're asking as the 110 kts is connected to the other
question, not the cross controlled stall question as referenced above,
but taking a guess......if you check question number one about dying at
the controls, the trim speed given was 110 kts. :-)

--
Dudley Henriques

[Gezellig[_2_]]

Jim Stewart presented the following explanation :
> gatt wrote:
>>
>> One of the folks around the hangar took his CFI practical last week. He
>> had his AGI so they threw out all of the Fundamentals of Instruction stuff
>> entirely during the oral.
>>
>> A question the examiner asked him: "You're flying cross-country and trimmed
>> at 110 knots. You die, and the engine quits. At what airspeed will the
>> aircraft strike the ground?"
>>
>> Another was, "You're turning final and you enter a cross-control stall. Is
>> it better to be in a slip, or a skid?"

> I'm wondering what the significance of posting
> this question is. Is it because everyone should
> know the answer or because on some level it is
> nonsensical?

Can't speak for gatt but the I take it for both. There are nonsensical
questions that need to be prepaered for after all its about passing a
test to get to the real learning.

[Mortimer Schnerd, RN[_2_]]

Jim Stewart wrote:
>>>> Another was, "You're turning final and you enter a cross-control
>>>> stall. Is it better to be in a slip, or a skid?"
>>>
>>> I'm wondering what the significance of posting this question is.
>>
>> They're aviation forums. Some people still actually like to discuss
>> aviation out here.
>
> I didn't mean to come off as a smart-ass. As
> I said, my instructor and I covered this well
> before I soloed. I assumed that every soloed
> student would know the answer, let alone a CFI
> candidate.
>
> I guess I was wrong.



I don't remember ever talking about this with my instructor. I seem to have
known the answer; just can't say where I got the information any more.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

[Gezellig[_2_]]

NW_Pilot was thinking very hard :
> "Gezellig" > wrote in message
> ...
>> On Thu, 29 May 2008 07:21:20 -0700, gatt wrote:
>>
>>> One of the folks around the hangar took his CFI practical last week. He
>>> had his AGI so they threw out all of the Fundamentals of Instruction
>>> stuff entirely during the oral.
>>>
>>> A question the examiner asked him: "You're flying cross-country and
>>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>>> will the aircraft strike the ground?
>>
>> That's easy, gatt. I wouldn't know.
>>
>> Or care.

> That summs it upp....

I have to admit, it was a humerous dodge to a question that I wrote
down, researched, then found out I was wrong. :'(

The good news I am still a student!

Forever. :-)

[Gezellig[_2_]]

Dudley Henriques laid this down on his screen :
> Gezellig wrote:
>> Dudley Henriques presented the following explanation :
>>> A slipped cross control stall as relates to spin entry is FAR less
>>> pro-spin than a skid entry.
>>
>> Dudley, I don't understand why that is? Are you assuming 110 nauts?
>>
>>

> Not sure what you're asking as the 110 kts is connected to the other
> question, not the cross controlled stall question as referenced above, but
> taking a guess......if you check question number one about dying at the
> controls, the trim speed given was 110 kts. :-)

lol

I got my answer from your other post. I got on track from the
discussion, I have no idea where I got off track on the 110 nauts.

I revel in my ineptitude. It makes me endearing. I hope I get laid
because of it.

No, forget that. I don't need another bimbette in my life.

[Dudley Henriques[_2_]]

Gezellig wrote:

>> Not sure what you're asking as the 110 kts is connected to the other
>> question, not the cross controlled stall question as referenced above,
>> but taking a guess......if you check question number one about dying
>> at the controls, the trim speed given was 110 kts. :-)
>
> lol
>
> I got my answer from your other post. I got on track from the
> discussion, I have no idea where I got off track on the 110 nauts.
>
> I revel in my ineptitude. It makes me endearing. I hope I get laid
> because of it.
>
> No, forget that. I don't need another bimbette in my life.
>
>

Usenet will do that to you sometimes, although I have to admit it hasn't
gotten me laid yet :-)
--
Dudley Henriques

[Gezellig[_2_]]

Michael Ash was thinking very hard :
> In rec.aviation.student gatt > wrote:
>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> will the aircraft strike the ground?"

> In addition to all the other factors discussed, your airspeed will be
> slightly lower than what you had trimmed due to the weight of your soul
> departing the aircraft.

Damn, I didn't take that in the weight balance shift forward and all
that...

> OK, so I don't really believe that, but I'd love to see what the guy would
> say if you told him that answer!

Stop that. Student pilots need no more confusion than I already have.
lol

[Michael Ash]

In rec.aviation.student Gezellig > wrote:
> Michael Ash was thinking very hard :
>> In rec.aviation.student gatt > wrote:
>>> A question the examiner asked him: "You're flying cross-country and
>>> trimmed at 110 knots. You die, and the engine quits. At what airspeed
>>> will the aircraft strike the ground?"
>
>> In addition to all the other factors discussed, your airspeed will be
>> slightly lower than what you had trimmed due to the weight of your soul
>> departing the aircraft.
>
> Damn, I didn't take that in the weight balance shift forward and all
> that...
>
>> OK, so I don't really believe that, but I'd love to see what the guy would
>> say if you told him that answer!
>
> Stop that. Student pilots need no more confusion than I already have.

Joking aside, if your straps were loose enough that you could slump
forward, that *would* affect your CG which would in turn affect your
trimmed airspeed.

There's another issue that I just thought of that I don't think anyone has
mentioned yet, though. Won't you get into a graveyard (bad terminology for
this scenario, as you're already dead) spiral? After all, if you could
stay straight and level just by taking your hands off the controls you
wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
if you start high enough, the correct answer to this question would be
whatever the terminal velocity of your fuselage is without its wings. Am I
off base here?

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Hilton]

Everyone who has replied has made one significant and incorrect assumption.
I would have replied, "Really really fast, yellow arc at least, perhaps at
or above Vne depending on the aircraft."

Why? Because all posts have made the (probably) incorrect assumption that
the aircraft somehow fly wings-levels to its demise. That just won't
happen. Forget dihedral, that won't stop it going into a spiral. Another
factor worth considering is that when the pilot dies, there is a really good
chance that the pilot will fall forward and possibly push on the yoke. With
a side stick, this will probably cause a bank as the pilot pulls sideways on
the stick.

Anyway, my point is, is that since no wings leveler or autopilot was
mentioned, it is almost guaranteed that the aircraft would enter a spiral
and trim speed does not apply in a spiral.

Hilton


"gatt" > wrote in message
. ..
>
> One of the folks around the hangar took his CFI practical last week. He
> had his AGI so they threw out all of the Fundamentals of Instruction stuff
> entirely during the oral.
>
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed will
> the aircraft strike the ground?"
>
> Another was, "You're turning final and you enter a cross-control stall. Is
> it better to be in a slip, or a skid?"
>
> -c

[Dudley Henriques[_2_]]

Hilton wrote:
> Everyone who has replied has made one significant and incorrect assumption.
> I would have replied, "Really really fast, yellow arc at least, perhaps at
> or above Vne depending on the aircraft."
>
> Why? Because all posts have made the (probably) incorrect assumption that
> the aircraft somehow fly wings-levels to its demise. That just won't
> happen. Forget dihedral, that won't stop it going into a spiral. Another
> factor worth considering is that when the pilot dies, there is a really good
> chance that the pilot will fall forward and possibly push on the yoke. With
> a side stick, this will probably cause a bank as the pilot pulls sideways on
> the stick.
>
> Anyway, my point is, is that since no wings leveler or autopilot was
> mentioned, it is almost guaranteed that the aircraft would enter a spiral
> and trim speed does not apply in a spiral.
>
> Hilton
>
>
> "gatt" > wrote in message
> . ..
>> One of the folks around the hangar took his CFI practical last week. He
>> had his AGI so they threw out all of the Fundamentals of Instruction stuff
>> entirely during the oral.
>>
>> A question the examiner asked him: "You're flying cross-country and
>> trimmed at 110 knots. You die, and the engine quits. At what airspeed will
>> the aircraft strike the ground?"
>>
>> Another was, "You're turning final and you enter a cross-control stall. Is
>> it better to be in a slip, or a skid?"
>>
>> -c
>
>
Really getting nitty here Hilton :-)

With the engine dead, and assuming good rigging, there is no specific
reason to assume a spiral. The initial question specified the engine
"quit". Again, assuming proper trim and no aerodynamic forces to induce
bank, the aircraft for all practical purposes anyway, can be assumed a
straight path into the ground.

Take out the proper trim and an idling engine and perhaps you have a
case for a spiral. Also, few aircraft are rigged perfectly so that also
could be a factor for a spiral.

Other than these things being present and considering the "spirit" of
the question, trim speed would be the answer for ground impact in my
opinion.

--
Dudley Henriques

[Steve Foley]

"Michael Ash" > wrote in message
...
> In rec.aviation.student gatt > wrote:
> > A question the examiner asked him: "You're flying cross-country and
> > trimmed at 110 knots. You die, and the engine quits. At what airspeed
> > will the aircraft strike the ground?"
>
> In addition to all the other factors discussed, your airspeed will be
> slightly lower than what you had trimmed due to the weight of your soul
> departing the aircraft.
>
> OK, so I don't really believe that, but I'd love to see what the guy would
> say if you told him that answer!
>

Your airspeed may also be slightly lower due to the weight of the fuel that
has departed the aircraft (through the engine)

[Stealth Pilot[_2_]]

On Thu, 29 May 2008 07:21:20 -0700, gatt
> wrote:

>
>One of the folks around the hangar took his CFI practical last week. He
>had his AGI so they threw out all of the Fundamentals of Instruction
>stuff entirely during the oral.
>
>A question the examiner asked him: "You're flying cross-country and
>trimmed at 110 knots. You die, and the engine quits. At what airspeed
>will the aircraft strike the ground?"
>
>Another was, "You're turning final and you enter a cross-control stall.
> Is it better to be in a slip, or a skid?"
>
>-c

first question the answer is 110 knots or thereabouts. when the engine
stops the aircraft will slow, lift will reduce and the aircraft will
enter a gentle dive, as the speed stabilises with the new engine power
(gravity) the aircraft will return to its trimmed speed and the angle
of decent will adjust until the aircraft is back in trim equilibrium.

second question is interesting. the two conditions will tend to cause
a stall in the opposite wing. so which is better to stall with the
inner wing first or the outer wing first?
skidding will stall the inner wing so the stall will add to the
already existing forces causing the turn so you will spin.
slipping will stall the outer wing so you will roll out of the turn
into a dive.
I think I'd rather stall in a slip.

Stealth Pilot

[Stealth Pilot[_2_]]

On Thu, 29 May 2008 19:28:41 -0400, Dudley Henriques
> wrote:

>gatt wrote:
>
>
>> Another one for the archives. Thanks, Dudley.
>>
>> I got the information about the question second-hand (the candidate told
>> the chief instructor who told me) so I'm not sure exactly what the
>> examiner as getting at. Now I'm really curious. It probably boils down
>> to the difference between a cross-control stall behavior in a slip
>> versus a skid. The FSDO examiners out here really hammer CFI candidates
>> on aerodynamics, or so I'm told, and less on the FOI if the candidate
>> appears reasonably capable of teaching. Seems appropriate enough.
>>
>> -c
>
>You're welcome.
>
>What they probably want is be assured that the CFI fully understands the
>dangers involved with skidding turns, especially at low altitude.
>
>To do it right, the CFI should use the necessity to impart this
>information to discuss and teach cross controlled stall in ALL
>configurations so that a BETTER understanding of the various
>ramifications involved be more understood.

oh bull**** dudley. they ask oddball questions like these to sort out
the rote learners who have swatted up all the past paper answers but
dont actually know diddly squat, and like MX, have no actual
understanding of what they sprout.

you can work out the answers from first principles if you actually
understand the fundamentals.

Stealth Pilot

[Stealth Pilot[_2_]]

On Thu, 29 May 2008 21:37:03 -0400, Gezellig >
wrote:

>Jim Stewart presented the following explanation :
>> gatt wrote:
>>>
>>> One of the folks around the hangar took his CFI practical last week. He
>>> had his AGI so they threw out all of the Fundamentals of Instruction stuff
>>> entirely during the oral.
>>>
>>> A question the examiner asked him: "You're flying cross-country and trimmed
>>> at 110 knots. You die, and the engine quits. At what airspeed will the
>>> aircraft strike the ground?"
>>>
>>> Another was, "You're turning final and you enter a cross-control stall. Is
>>> it better to be in a slip, or a skid?"
>
>> I'm wondering what the significance of posting
>> this question is. Is it because everyone should
>> know the answer or because on some level it is
>> nonsensical?
>
>Can't speak for gatt but the I take it for both. There are nonsensical
>questions that need to be prepaered for after all its about passing a
>test to get to the real learning.
>
NOOOO NO NO.

the whole purpose of these odd questions is that you cant prepare for
them.

however if you *understand* the aerodynamic principles and principles
of flight you can work out the answers.
never be afraid to work out the answer out aloud to them. it can show
more clearly than any other method that you understand ...or dont
understand what you've been taught.

Stealth Pilot

[Gig 601Xl Builder]

NW_Pilot wrote:
> "Robert M. Gary" > wrote in message
> ...
> On May 29, 7:21 am, gatt > wrote:
>> One of the folks around the hangar took his CFI practical last week. He
>> had his AGI so they threw out all of the Fundamentals of Instruction
>> stuff entirely during the oral.
>
> Huh, that's not right. There is nothing in the PTS that says you get
> to skip the FOI stuff just because you have an AGI. The only thing you
> get to skip is showing your FOI exam results. I had my AGI and
> probably spent 5 hours of my CFI oral on FOI stuff.
>
> -Robert, CFII, AGI
>
> FOI is my hangup right now....
>
>

Different rating same sort of issue.

When I was doing my check ride for my helo rating the tester started to
ask me a question on navigation and stopped about 5 words in and said,
"Never mind, you already have you private rating I don't need to cover
that."

[PPL-A (Canada)]

On May 29, 10:21*am, gatt > wrote:
> One of the folks around the hangar took his CFI practical last week. *He
> had his AGI so they threw out all of the Fundamentals of Instruction
> stuff entirely during the oral.
>
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"
>
> Another was, "You're turning final and you enter a cross-control stall.
> * Is it better to be in a slip, or a skid?"
>
> -c

First question: Is my student with me or not? If I have a student
then I'd hope the plane would touch down somewhere nearby in a
suitable field (or one hopes on a runway if possible) at stall speed +
5 knots or so, since by this point if I have a student on a cross
country they should already know about emergencies, especially engine-
out off field landings (and on-field landings). If not, and I fell
forward on the yolk then who knows what speed ... higher than 110
knots. If I didn't fall on the yolk then the crash would be somewhere
around the 110 knots the plane was trimmed for (minus some is the
aircraft is in the climbing phase of its phugoid, or plus some if in
the diving phase), as a phugoid is all but inevitable if the engine
goes after I die (since I won't be alive to trim for the new
condition ... no prop thrust, and no blast over the tail will change
the trim and start a phugoid, characteristics will depend on the
aircraft, the c.of.g and loading).

Second question: I'd have already taught my student not to do this at
or near pattern/circuit altitude, and particularly not on final at
only 500 AGL ... if he/she has blown the approach ... too high or too
fast ... so badly then they would know not to try to be a hero ... go
around! If it did happen ... I'd rather have the high wing stall
first, since I can't know for sure exactly what control inputs the
student is making (although I do know what the student should be
doing). In normal turn-to-final circumstances this would normally be
a dangerous skid, with the student trying to make the aircraft turn
faster than it should (or god forbid the student is holding back the
turn with the yolk and trying to initiate it only with the rudder)
with too much bottom rudder ... this I do not want. If this does
happen then I suppose the slip would be preferred in the scenario, as
I would rather have too much top rudder (or not enough bottom rudder)
and have the high wing stall first and pass through wings level making
for a somewhat easier recovery. And then I would chasten the student
after initiating a go-around and remind him/her on crosswind and
downwind what he/she should already be familiar with. And we would
keep in the circuit until the student got the landing right after the
go-around ... no slipping and skidding in turns in the circuit. Only
use the slip once established on final, and only to correct for
crosswind if you have the engine running. The only reason to slip
aggressively for low-time students is an engine-out-gotta-land-
right-"there"-so-I-have-to-slip-it-in-because-I'm-too-high-now
emergency scenario.

[F. Baum]

On May 29, 9:54*am, "Robert M. Gary" > wrote:
>
> Huh, that's not right. There is nothing in the PTS that says you get
> to skip the FOI stuff just because you have an AGI. The only thing you
> get to skip is showing your FOI exam results. I had my AGI and
> probably spent 5 hours of my CFI oral on FOI stuff.

Is there anything in the PTS that says you have to be retested on
previously completed material ? If you spent 5 hours on an oral your
examiner was either an idiot or he/she wanted to show you how much he/
she knew. I would have walked out if I were you. For an examiner to be
able determine if you are prepared should take minutes, not hours.

F Baum

> -Robert, CFII, AGI

[Scien]

>A question the examiner asked him: "You're flying cross-country and
>trimmed at 110 knots. You die, and the engine quits. At what airspeed
>will the aircraft strike the ground?"

So if you flip the order of events: "the engine quits, and you die" my
guess would be best glide. First step in engine failure... although
kinda pointless if you know you are dead in the next 10 seconds. Also
setting the airspeed might be a race with death?

[Gezellig]

On Fri, 30 May 2008 19:23:11 +0800, Stealth Pilot wrote:

>>> I'm wondering what the significance of posting
>>> this question is. Is it because everyone should
>>> know the answer or because on some level it is
>>> nonsensical?
>>
>>Can't speak for gatt but the I take it for both. There are nonsensical
>>questions that need to be prepaered for after all its about passing a
>>test to get to the real learning.
>>
> NOOOO NO NO.
>
> the whole purpose of these odd questions is that you cant prepare for
> them.
>
> however if you *understand* the aerodynamic principles and principles
> of flight you can work out the answers.
> never be afraid to work out the answer out aloud to them. it can show
> more clearly than any other method that you understand ...or dont
> understand what you've been taught.
>
> Stealth Pilot

I see your point.

[Michael[_1_]]

On May 30, 3:36*am, "Hilton" > wrote:
> Why? *Because all posts have made the (probably) incorrect assumption that
> the aircraft somehow fly wings-levels to its demise. *That just won't
> happen. *Forget dihedral, that won't stop it going into a spiral.

You're right, of course. The only way that will happen is with
artificial stability augmentation (a single axis autopilot). With a
two axis autopilot the plane will hit at stall speed. It may or may
not be wings level, depending on the stall characteristics.

See, this is what made the question such a good one. It allows lots
of room to explore different aspects of aerodynamic stability.

Michael

[Steve Hix]

In article >,
Dudley Henriques > wrote:
> Really getting nitty here Hilton :-)
>
> With the engine dead, and assuming good rigging, there is no specific
> reason to assume a spiral. The initial question specified the engine
> "quit". Again, assuming proper trim and no aerodynamic forces to induce
> bank, the aircraft for all practical purposes anyway, can be assumed a
> straight path into the ground.
>
> Take out the proper trim and an idling engine and perhaps you have a
> case for a spiral. Also, few aircraft are rigged perfectly so that also
> could be a factor for a spiral.

Turbulence would increase the likelihood of a spiral departure from
level flight, wouldn't it?

> Other than these things being present and considering the "spirit" of
> the question, trim speed would be the answer for ground impact in my
> opinion.

[Dudley Henriques[_2_]]

Stealth Pilot wrote:
> On Thu, 29 May 2008 19:28:41 -0400, Dudley Henriques
> > wrote:
>
>> gatt wrote:
>>
>>
>>> Another one for the archives. Thanks, Dudley.
>>>
>>> I got the information about the question second-hand (the candidate told
>>> the chief instructor who told me) so I'm not sure exactly what the
>>> examiner as getting at. Now I'm really curious. It probably boils down
>>> to the difference between a cross-control stall behavior in a slip
>>> versus a skid. The FSDO examiners out here really hammer CFI candidates
>>> on aerodynamics, or so I'm told, and less on the FOI if the candidate
>>> appears reasonably capable of teaching. Seems appropriate enough.
>>>
>>> -c
>> You're welcome.
>>
>> What they probably want is be assured that the CFI fully understands the
>> dangers involved with skidding turns, especially at low altitude.
>>
>> To do it right, the CFI should use the necessity to impart this
>> information to discuss and teach cross controlled stall in ALL
>> configurations so that a BETTER understanding of the various
>> ramifications involved be more understood.
>
> oh bull**** dudley. they ask oddball questions like these to sort out
> the rote learners who have swatted up all the past paper answers but
> dont actually know diddly squat, and like MX, have no actual
> understanding of what they sprout.
>
> you can work out the answers from first principles if you actually
> understand the fundamentals.
>
> Stealth Pilot
Right. I'll change my approach to flight instruction immediately :-)

--
Dudley Henriques

[Dudley Henriques[_2_]]

Steve Hix wrote:
> In article >,
> Dudley Henriques > wrote:
>> Really getting nitty here Hilton :-)
>>
>> With the engine dead, and assuming good rigging, there is no specific
>> reason to assume a spiral. The initial question specified the engine
>> "quit". Again, assuming proper trim and no aerodynamic forces to induce
>> bank, the aircraft for all practical purposes anyway, can be assumed a
>> straight path into the ground.
>>
>> Take out the proper trim and an idling engine and perhaps you have a
>> case for a spiral. Also, few aircraft are rigged perfectly so that also
>> could be a factor for a spiral.
>
> Turbulence would increase the likelihood of a spiral departure from
> level flight, wouldn't it?
>
>> Other than these things being present and considering the "spirit" of
>> the question, trim speed would be the answer for ground impact in my
>> opinion.
Yes. Anything that changed the basic balance equation that was in effect
when the trim was set would do that.

--
Dudley Henriques

[Dudley Henriques[_2_]]

Michael wrote:
> On May 30, 3:36 am, "Hilton" > wrote:
>> Why? Because all posts have made the (probably) incorrect assumption that
>> the aircraft somehow fly wings-levels to its demise. That just won't
>> happen. Forget dihedral, that won't stop it going into a spiral.
>
> You're right, of course. The only way that will happen is with
> artificial stability augmentation (a single axis autopilot). With a
> two axis autopilot the plane will hit at stall speed. It may or may
> not be wings level, depending on the stall characteristics.
>
> See, this is what made the question such a good one. It allows lots
> of room to explore different aspects of aerodynamic stability.
>
> Michael

I would respectfully disagree with you and Hilton on this one :-)There
should be no "of course" and no autopilot issues are involved in the
question that I can see.

The aircraft, if in trim at 110 kts will be trimmed for whatever angle
of attack is producing that airspeed. Unless there is something added to
the problem and assuming all factors normal with balance and stability
issues, what should be expected normally is a phugoid starting nose low
as the engine quits to recover the trim speed. I'm assuming no fuel
imbalance or rigging issues that could cause a bank input entry into the
problem.

So using just the aspects of the problem as presented;

Where the aircraft is along that phugoid and the exact airspeed to
expect at ground impact would depend on the altitude remaining and the
dampening properties present determining the decreasing phases of the
phugoid.

Just what is it that you are expecting to happen to cause the necessary
bank/lift imbalance to enter a nose low spiral?

--
Dudley Henriques

[Gezellig]

On Fri, 30 May 2008 12:32:00 -0400, Gezellig wrote:

> On Fri, 30 May 2008 19:23:11 +0800, Stealth Pilot wrote:
>
>>>> I'm wondering what the significance of posting
>>>> this question is. Is it because everyone should
>>>> know the answer or because on some level it is
>>>> nonsensical?
>>>
>>>Can't speak for gatt but the I take it for both. There are nonsensical
>>>questions that need to be prepaered for after all its about passing a
>>>test to get to the real learning.
>>>
>> NOOOO NO NO.
>>
>> the whole purpose of these odd questions is that you cant prepare for
>> them.
>>
>> however if you *understand* the aerodynamic principles and principles
>> of flight you can work out the answers.
>> never be afraid to work out the answer out aloud to them. it can show
>> more clearly than any other method that you understand ...or dont
>> understand what you've been taught.
>>
>> Stealth Pilot
>
> I see your point.

No, wait, that's your head. lol

I would think the purpose of gatt's question to be to learn the logical
sequences of thinking, of putting into practice what you have learned in
theory, when that time comes for things in air that you could rarely, if
ever, practice.

When was the last time you practiced being dead?

[Gezellig]

On Fri, 30 May 2008 19:09:52 +0800, Stealth Pilot wrote:

> first question the answer is 110 knots or thereabouts. when the engine
> stops the aircraft will slow, lift will reduce and the aircraft will
> enter a gentle dive, as the speed stabilises with the new engine power
> (gravity) the aircraft will return to its trimmed speed and the angle
> of decent will adjust until the aircraft is back in trim equilibrium.

Which is how to handle a stall with the proper AOA.

> second question is interesting. the two conditions will tend to cause
> a stall in the opposite wing. so which is better to stall with the
> inner wing first or the outer wing first?
> skidding will stall the inner wing so the stall will add to the
> already existing forces causing the turn so you will spin.
> slipping will stall the outer wing so you will roll out of the turn
> into a dive.

> I think I'd rather stall in a slip.

I'd rather dance in the rain.

shrunklink.com/arly

[Michael[_1_]]

On May 30, 2:47*pm, Dudley Henriques > wrote:
> Just what is it that you are expecting to happen to cause the necessary
> bank/lift imbalance to enter a nose low spiral?

Well, I am expecting normal behavior for a light airplane. Most light
airplanes have approximately neutral static and weakly negative
dynamic lateral (roll) stability. Thus, if left with no pilot input,
they will eventually roll into a turn. Maintaining AOA (which the
trim will do) will result in the increased airspeed.

Now the real question is why this is the case. Airplanes could be
built with positive dynamic lateral stability, and in fact ram-air
(square) parachutes (powered and unpowered) are built that way, which
is what makes it possible for them to be flown through clouds (absent
the legalities) with no gyros at all. However, airplanes are
generally not built that way. It's been tried before, and the results
were generally unsatisfactory.

Making the airplane too stable also made it too sluggish, and because
of the yaw-roll coupling involved gave it a really nasty ride in
turbulence.

A pretty good primer on stability issues can be found here:

http://selair.selkirk.bc.ca/aerodynamics1/Stability/Page5.html

Michael

[Dudley Henriques[_2_]]

Michael wrote:
> On May 30, 2:47 pm, Dudley Henriques > wrote:
>> Just what is it that you are expecting to happen to cause the necessary
>> bank/lift imbalance to enter a nose low spiral?
>
> Well, I am expecting normal behavior for a light airplane. Most light
> airplanes have approximately neutral static and weakly negative
> dynamic lateral (roll) stability.

I would respectfully disagree. An Extra 300, as do most high performance
aerobatic airplanes has neutral static stability, but your vanilla
Cessna or Piper with dihedral is designed with positive static stability
in mind. Even a high wing Cessna like the 190 or 195 with little
dihedral has positive static stability due to wing position.
High performance airplanes like a Pitts or Extra have neutral static
stability.
As for dynamic stability, it really isn't much of a factor in lateral
stability. The ailerons if mass balanced around the hinge line by
weight, and if comparatively free in movement, usually assure that the
pure lateral movement is heavily damped. However, cross effects in yaw
displacement can result in lateral oscillations and Dutch Roll.

I totally agree that excessive dihedral is bad. It works against good
rolling qualities and as you say, makes for an overly stable aircraft.
It's for this reason that airplanes requiring a fast roll rate like the
Extra or a fighter for example, don't have excessive dihedral.






Thus, if left with no pilot input,
> they will eventually roll into a turn.

Remember, we're dealing here with a dead engine. I'm still going to
stick with the spiel :-)) that says with a light GA airplane with
positive lateral stability built in with the normal dihedral found on
such airplanes and the engine dead, we're going to need a source for an
outside the system force strong enough to offset the countering dihedral
to any roll input to initiate the roll or yaw (or coupling if you wish)
that would end up with the aircraft banked enough to counter the
dihedral correcting it back into the normal phugoid I'm expecting.

>
> Now the real question is why this is the case. Airplanes could be
> built with positive dynamic lateral stability,

If the aircraft has dihedral, it has positive static lateral stability.
I don't see dynamic lateral stability as an issue here.




and in fact ram-air
> (square) parachutes (powered and unpowered) are built that way, which
> is what makes it possible for them to be flown through clouds (absent
> the legalities) with no gyros at all.

That's interesting. I never knew that. I knew Steve Snyder quite well. I
believe Steve had something to do with the design of the square chute. I
know he designed the sentinel as well as a thousand other things related
to parachuting. Quite a guy. I miss him. He morted in his F86 a while back.





> Making the airplane too stable also made it too sluggish, and because
> of the yaw-roll coupling involved gave it a really nasty ride in
> turbulence.

I completely agree.
>
> A pretty good primer on stability issues can be found here:
>
> http://selair.selkirk.bc.ca/aerodynamics1/Stability/Page5.html

I know the site. His stuff is generally very good. I do have some very
minor issues with his presentation on a few things.
DH
>
> Michael


--
Dudley Henriques

[Michael Ash]

In rec.aviation.student Michael > wrote:
> On May 30, 3:36?am, "Hilton" > wrote:
>> Why? ?Because all posts have made the (probably) incorrect assumption that
>> the aircraft somehow fly wings-levels to its demise. ?That just won't
>> happen. ?Forget dihedral, that won't stop it going into a spiral.
>
> You're right, of course. The only way that will happen is with
> artificial stability augmentation (a single axis autopilot). With a
> two axis autopilot the plane will hit at stall speed. It may or may
> not be wings level, depending on the stall characteristics.
>
> See, this is what made the question such a good one. It allows lots
> of room to explore different aspects of aerodynamic stability.

It's only good if the person asking the question intends this sort of
discussion, though. My mpression from the original context was that
they were searching for a single answer ("110kts") and wouldn't anticipate
this sort of varied response. If true, then that transforms it from a good
question to a bad question. It always drives me nuts when there's a
question on a test which has a "right" answer but is actually a very
complicated question with a lot of correct responses.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Dudley Henriques[_2_]]

Michael Ash wrote:
> In rec.aviation.student Michael > wrote:
>> On May 30, 3:36?am, "Hilton" > wrote:
>>> Why? ?Because all posts have made the (probably) incorrect assumption that
>>> the aircraft somehow fly wings-levels to its demise. ?That just won't
>>> happen. ?Forget dihedral, that won't stop it going into a spiral.
>> You're right, of course. The only way that will happen is with
>> artificial stability augmentation (a single axis autopilot). With a
>> two axis autopilot the plane will hit at stall speed. It may or may
>> not be wings level, depending on the stall characteristics.
>>
>> See, this is what made the question such a good one. It allows lots
>> of room to explore different aspects of aerodynamic stability.
>
> It's only good if the person asking the question intends this sort of
> discussion, though. My mpression from the original context was that
> they were searching for a single answer ("110kts") and wouldn't anticipate
> this sort of varied response. If true, then that transforms it from a good
> question to a bad question. It always drives me nuts when there's a
> question on a test which has a "right" answer but is actually a very
> complicated question with a lot of correct responses.
>


Welcome to the world of the FAA :-))

--
Dudley Henriques

[Michael Ash]

In rec.aviation.student Dudley Henriques > wrote:
> Michael Ash wrote:
>> It's only good if the person asking the question intends this sort of
>> discussion, though. My mpression from the original context was that
>> they were searching for a single answer ("110kts") and wouldn't anticipate
>> this sort of varied response. If true, then that transforms it from a good
>> question to a bad question. It always drives me nuts when there's a
>> question on a test which has a "right" answer but is actually a very
>> complicated question with a lot of correct responses.
>
> Welcome to the world of the FAA :-))

Heh heh heh heh heh... you mean you noticed it too?

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Dudley Henriques[_2_]]

Michael Ash wrote:
> In rec.aviation.student Dudley Henriques > wrote:
>> Michael Ash wrote:
>>> It's only good if the person asking the question intends this sort of
>>> discussion, though. My mpression from the original context was that
>>> they were searching for a single answer ("110kts") and wouldn't anticipate
>>> this sort of varied response. If true, then that transforms it from a good
>>> question to a bad question. It always drives me nuts when there's a
>>> question on a test which has a "right" answer but is actually a very
>>> complicated question with a lot of correct responses.
>> Welcome to the world of the FAA :-))
>
> Heh heh heh heh heh... you mean you noticed it too?
>

If you're following this thread, Michael and Hilton are not incorrect
even though I've chosen to disagree with them on this issue.
It's a complicated question that can easily get mired down in terms,
especially as the terms apply to stability issues with aircraft.
Under certain conditions, what Michael and Hilton have said would indeed
be correct. I've simply chosen to deal with the question as my
experience with the FAA is telling me was their intent :-)

--
Dudley Henriques

[Michael Ash]

In rec.aviation.student Dudley Henriques > wrote:
> Michael Ash wrote:
>> In rec.aviation.student Dudley Henriques > wrote:
>>> Michael Ash wrote:
>>>> It's only good if the person asking the question intends this sort of
>>>> discussion, though. My mpression from the original context was that
>>>> they were searching for a single answer ("110kts") and wouldn't anticipate
>>>> this sort of varied response. If true, then that transforms it from a good
>>>> question to a bad question. It always drives me nuts when there's a
>>>> question on a test which has a "right" answer but is actually a very
>>>> complicated question with a lot of correct responses.
>>> Welcome to the world of the FAA :-))
>>
>> Heh heh heh heh heh... you mean you noticed it too?
>
> If you're following this thread, Michael and Hilton are not incorrect
> even though I've chosen to disagree with them on this issue.
> It's a complicated question that can easily get mired down in terms,
> especially as the terms apply to stability issues with aircraft.
> Under certain conditions, what Michael and Hilton have said would indeed
> be correct. I've simply chosen to deal with the question as my
> experience with the FAA is telling me was their intent :-)

Yeah, I get that. That's the whole trouble; there's a fairly large
universe of discussion about the topic but the question is apparently
intended to ignore most of it. Of course as you implied this isn't exactly
rare.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Stealth Pilot[_2_]]

On Fri, 30 May 2008 14:47:17 -0400, Dudley Henriques
> wrote:


>the problem and assuming all factors normal with balance and stability
>issues, what should be expected normally is a phugoid starting nose low
>as the engine quits to recover the trim speed. I'm assuming no fuel
>imbalance or rigging issues that could cause a bank input entry into the

there is no reason for you to have a fugoid.
when you pull off throttle the aircraft simulataneously slows slightly
and enters a glide decent. I've never encountered any phugoid tendency
in that manouver.

I know of one instance where this occurred in real life.
a couple of years ago there was a charter flight out of perth in a
pressurised twin. there was some pressurisation problem and the pilot
wasnt quick enough getting to the mask to stay concious. the end
result was that the aircraft climbed way above unpressurised breathing
altitude and all on board died. the aircraft crossed australia until
somewhere in queensland it ran out of fuel. the aircraft was being
tracked by others and the report is that the aircraft entered a gentle
glide decent and was destroyed in the impact.
there was no report of instability during the last part of the flight.

Stealth Pilot

[Dudley Henriques[_2_]]

Michael Ash wrote:
> In rec.aviation.student Dudley Henriques > wrote:
>> Michael Ash wrote:
>>> In rec.aviation.student Dudley Henriques > wrote:
>>>> Michael Ash wrote:
>>>>> It's only good if the person asking the question intends this sort of
>>>>> discussion, though. My mpression from the original context was that
>>>>> they were searching for a single answer ("110kts") and wouldn't anticipate
>>>>> this sort of varied response. If true, then that transforms it from a good
>>>>> question to a bad question. It always drives me nuts when there's a
>>>>> question on a test which has a "right" answer but is actually a very
>>>>> complicated question with a lot of correct responses.
>>>> Welcome to the world of the FAA :-))
>>> Heh heh heh heh heh... you mean you noticed it too?
>> If you're following this thread, Michael and Hilton are not incorrect
>> even though I've chosen to disagree with them on this issue.
>> It's a complicated question that can easily get mired down in terms,
>> especially as the terms apply to stability issues with aircraft.
>> Under certain conditions, what Michael and Hilton have said would indeed
>> be correct. I've simply chosen to deal with the question as my
>> experience with the FAA is telling me was their intent :-)
>
> Yeah, I get that. That's the whole trouble; there's a fairly large
> universe of discussion about the topic but the question is apparently
> intended to ignore most of it. Of course as you implied this isn't exactly
> rare.
>

This brings up something every pilot should remember about "questions"
from the FAA.
The FAA by the very nature of it's purpose, is a black and white
organization. As such, they concentrate heavily on the black and white
area that encompasses the rules and regulations scenario. Their
"questions" in many cases, are questions that require a black and white
answer to "pass" the obstacle in the path of a pilot.
The problem with this approach is that flying an airplane is NEVER a
black and white situation. Flying an airplane, in every instance, is a
dynamic and ever changing environment where the answer to ANY question
can be A one second and B the next.

This places an unwritten responsibility on the CFI to insure that the
student knows what they have to know to pass the tests, but as well that
the student knows a hell of a lot MORE than the answer required to pass
that test

--
Dudley Henriques

[Dudley Henriques[_2_]]

Stealth Pilot wrote:
> On Fri, 30 May 2008 14:47:17 -0400, Dudley Henriques
> > wrote:
>
>
>> the problem and assuming all factors normal with balance and stability
>> issues, what should be expected normally is a phugoid starting nose low
>> as the engine quits to recover the trim speed. I'm assuming no fuel
>> imbalance or rigging issues that could cause a bank input entry into the
>
> there is no reason for you to have a fugoid.
> when you pull off throttle the aircraft simulataneously slows slightly
> and enters a glide decent. I've never encountered any phugoid tendency
> in that manouver.
>
> I know of one instance where this occurred in real life.
> a couple of years ago there was a charter flight out of perth in a
> pressurised twin. there was some pressurisation problem and the pilot
> wasnt quick enough getting to the mask to stay concious. the end
> result was that the aircraft climbed way above unpressurised breathing
> altitude and all on board died. the aircraft crossed australia until
> somewhere in queensland it ran out of fuel. the aircraft was being
> tracked by others and the report is that the aircraft entered a gentle
> glide decent and was destroyed in the impact.
> there was no report of instability during the last part of the flight.
>
> Stealth Pilot
>
Any phugoid in pitch and the time line of that Phugoid will be directly
associated with the dynamic stability of that specific aircraft in pitch.

It all depends on the specific aircraft.

--
Dudley Henriques

[Christopher Brian Colohan]

gatt > writes:
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"

Okay, I can settle the debate. I had this happen to me this morning.

I was flying my R/C plane, and the engine quit since I mis-estimated
the battery life. The plane started gliding fairly slowly, but soon
glided below the lip of a hill on the far side of the field (aka,
pilot may as well as been dead, since I had no control).

How fast did it hit? Must have been faster than I thought, since it
sheared the motor shaft clean off after landing in long grass...

Okay, perhaps this doesn't settle anything. Can we try this in MS
Flight Simulator to see what happens? :-)

Chris

[Christopher Brian Colohan]

Dudley Henriques > writes:
> Michael Ash wrote:
>> It always drives me nuts when there's a question on a test which
>> has a "right" answer but is actually a very complicated question
>> with a lot of correct responses.
>
> Welcome to the world of the FAA :-))

I'm currently studying for my IFR written. I'm not sure which is my
favourite question:

a) the chart which is so badly reproduced you can't actually read the
numbers on it, and the King DVDs say it has been that way for years
and so you should memorize the correct answer to the question, or

b) the question where you have to match the VOR needles to the chart
-- but the FAA has updated the chart with a newer version which has
moved the fix. As a result it no longer matches the VOR settings or
the given answer choices (fortunately you can still figure out the
intended right answer with a bit of extra logic).

Chris

[Hilton]

Dudley wrote:
> Any phugoid in pitch and the time line of that Phugoid will be directly
> associated with the dynamic stability of that specific aircraft in pitch.

Whenever I see the word "phugoid" I think UA 232.

Hilton

[Dudley Henriques[_2_]]

Hilton wrote:
> Dudley wrote:
>> Any phugoid in pitch and the time line of that Phugoid will be directly
>> associated with the dynamic stability of that specific aircraft in pitch.
>
> Whenever I see the word "phugoid" I think UA 232.
>
> Hilton
>
>
Al Haynes and company. What a magnificent job of flying those guys
pulled off that day. Haynes is one of the TRUE professionals in the
business. And the guys with him that afternoon were no slouches either.
:-)

--
Dudley Henriques

[Larry Dighera]

On Sun, 1 Jun 2008 20:43:14 -0700, "Hilton" > wrote
in >:

>Dudley wrote:
>> Any phugoid in pitch and the time line of that Phugoid will be directly
>> associated with the dynamic stability of that specific aircraft in pitch.
>
>Whenever I see the word "phugoid" I think UA 232.
>
>Hilton
>


I once had a former chief engineer with Burroughs demonstrate phugoid
oscillation to me by grasping a book by the top in one hand and the
bottom in the other, holding it horizontally, and tossing it into the
air so that it spun on its long axis. Behold, the top and bottom
sides of the book swapped places in mid air. :)

[Maxwell[_2_]]

"Dudley Henriques" > wrote in message
...
>
> Just a few thoughts on this if I may.
>
Why certainly, we have been breathlessly waiting your 50000 word essay. Will
there be slides this time?

[Maxwell[_2_]]

"Dudley Henriques" > wrote in message
...

>> you can work out the answers from first principles if you actually
>> understand the fundamentals.

There's your problem......

[Dylan Smith]

On 2008-05-29, gatt > wrote:
> A question the examiner asked him: "You're flying cross-country and
> trimmed at 110 knots. You die, and the engine quits. At what airspeed
> will the aircraft strike the ground?"

CLOSE to 110 knots - factors will be the speed the aircraft will assume
at that trim setting with a windmilling propellor, and how big any
phugoid oscillations in the aircraft type is.

> Another was, "You're turning final and you enter a cross-control stall.
> Is it better to be in a slip, or a skid?"

Slip, in most aircraft. I actually tried to goad my Cessna 140 into a
spin from a slipped 'base to final' turn at altitude, and all it would
do was shake and mush. In a skidding turn though it'd happily do a spin
entry.

--
From the sunny Isle of Man.
Yes, the Reply-To email address is valid.

[Dylan Smith]

On 2008-05-30, Michael Ash > wrote:
> There's another issue that I just thought of that I don't think anyone has
> mentioned yet, though. Won't you get into a graveyard (bad terminology for
> this scenario, as you're already dead) spiral? After all, if you could
> stay straight and level just by taking your hands off the controls you
> wouldn't need to fear IMC with no gyroscopic instruments.

It depends on the aircraft.

My old Cessna 140 would fly all day (well, until the fuel ran out!)
without touching the controls. There are instances of this kind of plane
being hand propped and getting away from the owner, and flying hundreds
of miles pilotless.

Something like a Cessna 172 will also do it. IIRC, the manual for the
C172N advises a VFR only pilot who has got trapped on top, to trim the
aircraft for a descent, and only make turns using gentle rudder
pressures.

This is of course assuming the air is reasonably smooth. You need those
gyros because at some point, a pilot flying IFR is going to want to
change course, or fly a procedure turn, or intercept the final approach
course etc. even in an aircraft that will happily fly all day without
anyone touching the controls, that's going to be tough with no gyros!

--
From the sunny Isle of Man.
Yes, the Reply-To email address is valid.

[Dylan Smith]

On 2008-05-30, Hilton > wrote:
> Why? Because all posts have made the (probably) incorrect assumption that
> the aircraft somehow fly wings-levels to its demise.

In a plane that cruises at 110kt, though, this probably isn't an
incorrect assumption - many aircraft in this class will fly wings level
all day in smooth air. A properly rigged C172 will do it. My old C140
did it. Never tried it in the Auster, but that will probably do it too.

A Beech Bonanza probably won't (at least none of the Bonanzas I've
flown) but they don't cruise at 110kt either.

--
From the sunny Isle of Man.
Yes, the Reply-To email address is valid.

[More_Flaps]

On Jun 2, 10:26*pm, Dylan Smith > wrote:
> On 2008-05-30, Hilton > wrote:
>
> > Why? *Because all posts have made the (probably) incorrect assumption that
> > the aircraft somehow fly wings-levels to its demise.
>
> In a plane that cruises at 110kt, though, this probably isn't an
> incorrect assumption - many aircraft in this class will fly wings level
> all day in smooth air. A properly rigged C172 will do it. My old C140
> did it. Never tried it in the Auster, but that will probably do it too.
>
> A Beech Bonanza probably won't (at least none of the Bonanzas I've
> flown) but they don't cruise at 110kt either.
>

Have you flown a 172 that would fly hands off for long periods? I've
15 different 172s and not one would fly hands off for more than 30s.

Cheers

[Dylan Smith]

On 2008-05-30, Michael > wrote:
> the legalities) with no gyros at all. However, airplanes are
> generally not built that way. It's been tried before, and the results
> were generally unsatisfactory.

Well, unless you consider a Champ unsatisfactory!
This one flew for two hours sans pilot, after it was hand propped with
the throttle wide open:

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20011228X02460&key=1

There was another one in similar circumstances which I think was is
Illinois, which flew until it ran out of fuel. I think that may have
been a Taylorcraft - it made what looked like a passable forced landing
into a cornfield.

--
From the sunny Isle of Man.
Yes, the Reply-To email address is valid.

[Dudley Henriques[_2_]]

Maxwell wrote:
> "Dudley Henriques" > wrote in message
> ...
>
>>> you can work out the answers from first principles if you actually
>>> understand the fundamentals.
>
> There's your problem......
>
>
Please check your quotes more carefully. I didn't write this.

--
Dudley Henriques

[Gezellig]

On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:

> Joking aside, if your straps were loose enough that you could slump
> forward, that *would* affect your CG which would in turn affect your
> trimmed airspeed.
>
> There's another issue that I just thought of that I don't think anyone has
> mentioned yet, though. Won't you get into a graveyard (bad terminology for
> this scenario, as you're already dead) spiral? After all, if you could
> stay straight and level just by taking your hands off the controls you
> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
> if you start high enough, the correct answer to this question would be
> whatever the terminal velocity of your fuselage is without its wings. Am I
> off base here?

You fly until gassless, stall, nose down, then descend too rapidly,
striking the ground with the wings ripped off. Works for me.

[Robert M. Gary]

On May 30, 9:00*am, "F. Baum" > wrote:

> Is there anything in the PTS that says you have to be retested on
> previously completed material ? If you spent 5 hours on an oral your
> examiner was either an idiot or he/she wanted to show you how much he/
> she knew. I would have walked out if I were you. For an examiner to be
> able determine if you are prepared should take minutes, not hours.

I don't think a 5 hour oral is odd at all for the CFI exam. I know
some PI/DE's schedule a full day for the oral and another day for
flying. Do you really know any initial CFI oral that lasted minutes?

-Robert

[Ricky]

On May 29, 9:58*am, Bertie the Bunyip > wrote:

> gatt > wrote ;

> > A question the examiner asked him: "You're flying cross-country
and
> > trimmed at 110 knots. You die, and the engine quits. At what airspeed
> > will the aircraft strike the ground?"
>
> He's obviously looking at getting an answer that it will be the same
> speed, but that's not correct. It probably wouldn;'t be far off it, but
> the thrust line and any up or down thrust will play a big part in what
> the airplane settles at after the engine dies.

> Bertie

Wait, wait, wait...around 110 knots? I must be missing sumthin. Why
would the a/c hit around 110? Uhh..this commercial pilot feels really
stupid but I don't get it. My assumption is; engine quits-airplane
slows down; pilot dies, engine quits-airplane spins in but this seems
to have a bunch of "what-ifs" to it, as well.

Ricky

[Vaughn Simon]

"Robert M. Gary" > wrote in message
...
On May 30, 9:00 am, "F. Baum" > wrote:

I don't think a 5 hour oral is odd at all for the CFI exam. I know
some PI/DE's schedule a full day for the oral and another day for
flying. Do you really know any initial CFI oral that lasted minutes?

Mine was something less than two hours. The whole thing was probably half a
day, but that included the paperwork. (Mine was unusual in that it was with a
designee.)

Vaughn

[Dudley Henriques[_2_]]

Vaughn Simon wrote:
> "Robert M. Gary" > wrote in message
> ...
> On May 30, 9:00 am, "F. Baum" > wrote:
>
> I don't think a 5 hour oral is odd at all for the CFI exam. I know
> some PI/DE's schedule a full day for the oral and another day for
> flying. Do you really know any initial CFI oral that lasted minutes?
>
> Mine was something less than two hours. The whole thing was probably half a
> day, but that included the paperwork. (Mine was unusual in that it was with a
> designee.)
>
> Vaughn
>
>
Mine was about two hours for the oral.

--
Dudley Henriques

[Michael Ash]

In rec.aviation.student Ricky > wrote:
> On May 29, 9:58?am, Bertie the Bunyip > wrote:
>
>> gatt > wrote ;
>
> > > A question the examiner asked him: "You're flying cross-country
> and
>> > trimmed at 110 knots. You die, and the engine quits. At what airspeed
>> > will the aircraft strike the ground?"
>>
>> He's obviously looking at getting an answer that it will be the same
>> speed, but that's not correct. It probably wouldn;'t be far off it, but
>> the thrust line and any up or down thrust will play a big part in what
>> the airplane settles at after the engine dies.
>
>> Bertie
>
> Wait, wait, wait...around 110 knots? I must be missing sumthin. Why
> would the a/c hit around 110? Uhh..this commercial pilot feels really
> stupid but I don't get it. My assumption is; engine quits-airplane
> slows down; pilot dies, engine quits-airplane spins in but this seems
> to have a bunch of "what-ifs" to it, as well.

The first two steps you mention are correct but incomplete. The real
sequence goes: engine quits, airplane slows down, airplane begins to
descend, descent causes airplane to speed up, speed decreases the descent,
airplane slows down, airplane descends more, airplane speeds up, etc.

This cycle of increasing and decreasing airspeeds coupled with slower and
faster descents is called a phugoid. It's caused by the airplane
attempting to return to the originally trimmed angle of attack and thus
original airspeed. Depending on the airplane it may continue all the way
to the ground or it may damp out beforehand.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Michael Ash]

In rec.aviation.student Gezellig > wrote:
> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>
>> Joking aside, if your straps were loose enough that you could slump
>> forward, that *would* affect your CG which would in turn affect your
>> trimmed airspeed.
>>
>> There's another issue that I just thought of that I don't think anyone has
>> mentioned yet, though. Won't you get into a graveyard (bad terminology for
>> this scenario, as you're already dead) spiral? After all, if you could
>> stay straight and level just by taking your hands off the controls you
>> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
>> if you start high enough, the correct answer to this question would be
>> whatever the terminal velocity of your fuselage is without its wings. Am I
>> off base here?
>
> You fly until gassless, stall, nose down, then descend too rapidly,
> striking the ground with the wings ripped off. Works for me.

You don't stall, because when the engine quits the airplane will start to
descend, maintaining approximately the original airspeed.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Just go look it up!]

On Mon, 02 Jun 2008 23:30:12 -0500, Michael Ash >
wrote:

>In rec.aviation.student Gezellig > wrote:
>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>>
>>> Joking aside, if your straps were loose enough that you could slump
>>> forward, that *would* affect your CG which would in turn affect your
>>> trimmed airspeed.
>>>
>>> There's another issue that I just thought of that I don't think anyone has
>>> mentioned yet, though. Won't you get into a graveyard (bad terminology for
>>> this scenario, as you're already dead) spiral? After all, if you could
>>> stay straight and level just by taking your hands off the controls you
>>> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
>>> if you start high enough, the correct answer to this question would be
>>> whatever the terminal velocity of your fuselage is without its wings. Am I
>>> off base here?
>>
>> You fly until gassless, stall, nose down, then descend too rapidly,
>> striking the ground with the wings ripped off. Works for me.
>
>You don't stall, because when the engine quits the airplane will start to
>descend, maintaining approximately the original airspeed.

Unless the autopilot is engaged..............

[Michael Ash]

In rec.aviation.student Just go look it up! > wrote:
> On Mon, 02 Jun 2008 23:30:12 -0500, Michael Ash >
> wrote:
>
>>In rec.aviation.student Gezellig > wrote:
>>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>>>
>>>> Joking aside, if your straps were loose enough that you could slump
>>>> forward, that *would* affect your CG which would in turn affect your
>>>> trimmed airspeed.
>>>>
>>>> There's another issue that I just thought of that I don't think anyone has
>>>> mentioned yet, though. Won't you get into a graveyard (bad terminology for
>>>> this scenario, as you're already dead) spiral? After all, if you could
>>>> stay straight and level just by taking your hands off the controls you
>>>> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
>>>> if you start high enough, the correct answer to this question would be
>>>> whatever the terminal velocity of your fuselage is without its wings. Am I
>>>> off base here?
>>>
>>> You fly until gassless, stall, nose down, then descend too rapidly,
>>> striking the ground with the wings ripped off. Works for me.
>>
>>You don't stall, because when the engine quits the airplane will start to
>>descend, maintaining approximately the original airspeed.
>
> Unless the autopilot is engaged..............

The original question specified "trimmed at 110 knots" which implies that
the autopilot is not engaged.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Bertie the Bunyip[_25_]]

Ricky > wrote in news:44a0c8ff-a313-4436-9d19-
:

> On May 29, 9:58*am, Bertie the Bunyip > wrote:
>
>> gatt > wrote ;
>
> > > A question the examiner asked him: "You're flying cross-country
> and
>> > trimmed at 110 knots. You die, and the engine quits. At what
airspeed
>> > will the aircraft strike the ground?"
>>
>> He's obviously looking at getting an answer that it will be the same
>> speed, but that's not correct. It probably wouldn;'t be far off it,
but
>> the thrust line and any up or down thrust will play a big part in
what
>> the airplane settles at after the engine dies.
>
>> Bertie
>
> Wait, wait, wait...around 110 knots? I must be missing sumthin. Why
> would the a/c hit around 110? Uhh..this commercial pilot feels really
> stupid but I don't get it. My assumption is; engine quits-airplane
> slows down; pilot dies, engine quits-airplane spins in but this seems
> to have a bunch of "what-ifs" to it, as well.
>
> Ricky
>

Nah, its trimmed for 110 so it will tend to stay there regradless of the
power. It'll start a dive and gravity will keep it going pretty much
that speed. My point was that trim also counteracts some of the thrust
on most airplanes since the thrustline is often a compromise, so while
110 knots woudl be theoretically the right answer, in the event it would
be a bit off that.

Try it , though. Trim hands off and then close the throttle without
touching the stick and the airplane will just dive while retaining
approximately your trimmed speed.



Bertie

[Gezellig[_2_]]

Michael Ash pretended :
> In rec.aviation.student Gezellig > wrote:
>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>>
>>> Joking aside, if your straps were loose enough that you could slump
>>> forward, that *would* affect your CG which would in turn affect your
>>> trimmed airspeed.
>>>
>>> There's another issue that I just thought of that I don't think anyone has
>>> mentioned yet, though. Won't you get into a graveyard (bad terminology for
>>> this scenario, as you're already dead) spiral? After all, if you could
>>> stay straight and level just by taking your hands off the controls you
>>> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
>>> if you start high enough, the correct answer to this question would be
>>> whatever the terminal velocity of your fuselage is without its wings. Am I
>>> off base here?
>>
>> You fly until gassless, stall, nose down, then descend too rapidly,
>> striking the ground with the wings ripped off. Works for me.

> You don't stall, because when the engine quits the airplane will start to
> descend, maintaining approximately the original airspeed.

At what point do you expect to lose the wings via "the correct answer
to this question would be whatever the terminal velocity of your
fuselage is without its wings."?

[Michael Ash]

In rec.aviation.student Gezellig > wrote:
> Michael Ash pretended :
>> In rec.aviation.student Gezellig > wrote:
>>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>>>
>>>> Joking aside, if your straps were loose enough that you could slump
>>>> forward, that *would* affect your CG which would in turn affect your
>>>> trimmed airspeed.
>>>>
>>>> There's another issue that I just thought of that I don't think anyone has
>>>> mentioned yet, though. Won't you get into a graveyard (bad terminology for
>>>> this scenario, as you're already dead) spiral? After all, if you could
>>>> stay straight and level just by taking your hands off the controls you
>>>> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
>>>> if you start high enough, the correct answer to this question would be
>>>> whatever the terminal velocity of your fuselage is without its wings. Am I
>>>> off base here?
>>>
>>> You fly until gassless, stall, nose down, then descend too rapidly,
>>> striking the ground with the wings ripped off. Works for me.
>
>> You don't stall, because when the engine quits the airplane will start to
>> descend, maintaining approximately the original airspeed.
>
> At what point do you expect to lose the wings via "the correct answer
> to this question would be whatever the terminal velocity of your
> fuselage is without its wings."?

If you enter a spiral dive as I surmised, the wings fall off either when
you exceed Vne or when you exceed the maximum loading the wings can
support, whichever comes first. However it would seem that whether this
happens or not will depend on the airplane in question.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Michael[_1_]]

On May 30, 6:25*pm, Dudley Henriques > wrote:
> I would respectfully disagree. An Extra 300, as do most high performance
> aerobatic airplanes has neutral static stability, but your vanilla
> Cessna or Piper with dihedral is designed with positive static stability
> in mind.

The positive static stability, when present, is slight. More to the
point, it is only slightly positive around the zero point. Once an
excursion in roll gets past a few degrees, the stability is negative
(for a while) and the new stability point is in a significant bank (or
non-existent).

> As for dynamic stability, it really isn't much of a factor in lateral
> stability. The ailerons if mass balanced around the hinge line by
> weight, and if comparatively free in movement, usually assure that the
> pure lateral movement is heavily damped.

And that's the point. Dynamic stability is generally mildly negative,
and once a slight displacement from zero occurs, the restoring force
from the mild positive static stability starts a very mild oscillation
that will eventually take you outside the area of positive static
stability. Once that occurs, dynamic stability is indeed no longer
important.

Even a plane with comparatively good lateral stability will eventually
wind up in a spiral once something like turbulence disturbs it. In
some cases it won't happen - combine a very stable plane with very
smooth air, and it might fly wings level for a long time. It has
happened. Also note that the stability improves with lower weight
(this is true of the longitudinal axis as well - that's why the
allowable cg range on most light airplanes is wider at lower weights)
so we do have these stories of planes without pilots flying just fine
for hours.

I recall one particular sad incident where a Pilatus Porter dropping
jumpers lost the yoke - it literally came off in the pilot's hands.
The pilot elected to bail out (which was, IMO, the wrong call - a
plane can be landed with rudder, throttle, and trim). His parachute
malfunctioned, and the pilot died. The plane eventually ran out of
fuel and 'landed' in a field. After a few minor repairs, it was flown
out.

These things do happen, but they are the exception. Under most normal
conditions, the combination of neutral or weakly positive static
stability and negative dynamic stability in the lateral axis will
eventually put the plane into a spiral.

> Remember, we're dealing here with a dead engine. I'm still going to
> stick with the spiel :-)) that says with a light GA airplane with
> positive lateral stability built in with the normal dihedral found on
> such airplanes and the engine dead, we're going to need a source for an
> outside the system force strong enough to offset the countering dihedral
> to any roll input to initiate the roll or yaw (or coupling if you wish)
> that would end up with the aircraft banked enough to counter the
> dihedral correcting it back into the normal phugoid I'm expecting.

Sure - but that source will be found in the normal turbulence found on
most days. There are also additional factors.

First off, any side-by-side airplane with only one person on board is
going to be slightly out of balance laterally. Any plane with fuel
feed from a single wing tank, or a less-than-perfect 'both' feed
(which is most of them) will develop an imbalance. So what we need to
postulate is a plane that is tandem seating with a header tank (like
an old-style Champ or maybe a Cub) and then, on a really smooth day,
it might actually stay wings level.

> If the aircraft has dihedral, it has positive static lateral stability.

That's not necessarily the case. There can be other factors that
affect stability that would overcome a small amount of dihedral.
Remember that most airplanes have strong yaw stability, and that
weakens roll stability because yaw and roll are strongly coupled.

> That's interesting. I never knew that.> > A pretty good primer on stability issues can be found here:
> >http://selair.selkirk.bc.ca/aerodynamics1/Stability/Page5.html
> I know the site. His stuff is generally very good. I do have some very
> minor issues with his presentation on a few things.

I also like the site. The particular link includes much of what I
posted, including the assertion that most light planes left to
themselves will wind up in a spiral.

Of course as you mentioned elsewhere, this isn't the sort of
discussion you would have with the average FAA ops inspector. I knew
a couple who would have appreciated it in Houston. Neither one is
still with the FAA.

Michael

[Dudley Henriques[_2_]]

Below is a very well done white paper on stability by Russel Williams
that addresses much of what we have been discussing.

The long and short of it in my opinion is that positive lateral
stability is present in GA airplanes and they will tend to recover from
the sideslip coupling. Your key point addresses potential disturbances
that can indeed exceed this recovery tendency.
I agree totally with you that such a disturbance can exceed positive
stability tendencies if strong enough.

I believe you will find this paper interesting and informational.


http--soar.wichita.edu-dspace-bitstream-10057-754-1-t05045.pdf.webloc



--
Dudley Henriques

[Bertie the Bunyip[_25_]]

Michael Ash > wrote in
:

> In rec.aviation.student Gezellig > wrote:
>> Michael Ash pretended :
>>> In rec.aviation.student Gezellig > wrote:
>>>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>>>>
>>>>> Joking aside, if your straps were loose enough that you could
>>>>> slump forward, that *would* affect your CG which would in turn
>>>>> affect your trimmed airspeed.
>>>>>
>>>>> There's another issue that I just thought of that I don't think
>>>>> anyone has mentioned yet, though. Won't you get into a graveyard
>>>>> (bad terminology for this scenario, as you're already dead)
>>>>> spiral? After all, if you could stay straight and level just by
>>>>> taking your hands off the controls you wouldn't need to fear IMC
>>>>> with no gyroscopic instruments. So it seems that if you start high
>>>>> enough, the correct answer to this question would be whatever the
>>>>> terminal velocity of your fuselage is without its wings. Am I
>>>>> off base here?
>>>>
>>>> You fly until gassless, stall, nose down, then descend too rapidly,
>>>> striking the ground with the wings ripped off. Works for me.
>>
>>> You don't stall, because when the engine quits the airplane will
>>> start to descend, maintaining approximately the original airspeed.
>>
>> At what point do you expect to lose the wings via "the correct answer
>> to this question would be whatever the terminal velocity of your
>> fuselage is without its wings."?
>
> If you enter a spiral dive as I surmised, the wings fall off either
> when you exceed Vne or when you exceed the maximum loading the wings
> can support, whichever comes first. However it would seem that whether
> this happens or not will depend on the airplane in question.

Well, the wings won't come off as you exceed VNE. You have a good 10% on
top of that before anything will happen.
Something nasty will at the load limit, though. Not the published one,
of course, but at 50% over that. At the published load limit you are
guarunteed that the airplane will not permanently deform. 50% over that
you're guaunteed it will remain in one piece. Over that you're on your
own. It;s not quite as tidy as all that, though and with most light
planes it's probably flutter that's going to pull it apart and that will
probably be brought on by a combination of load and speed. This is not
to say it's safe to operate at or near the red line or load limit.
It isn't.



Bertie
>

[Bertie the Bunyip[_25_]]

Michael > wrote in
:

> On May 30, 6:25*pm, Dudley Henriques > wrote:
>> I would respectfully disagree. An Extra 300, as do most high
>> performance aerobatic airplanes has neutral static stability, but
>> your vanilla Cessna or Piper with dihedral is designed with positive
>> static stability in mind.
>
> The positive static stability, when present, is slight. More to the
> point, it is only slightly positive around the zero point. Once an
> excursion in roll gets past a few degrees, the stability is negative
> (for a while) and the new stability point is in a significant bank (or
> non-existent).
>
>> As for dynamic stability, it really isn't much of a factor in lateral
>> stability. The ailerons if mass balanced around the hinge line by
>> weight, and if comparatively free in movement, usually assure that
>> the pure lateral movement is heavily damped.
>
> And that's the point. Dynamic stability is generally mildly negative,
> and once a slight displacement from zero occurs, the restoring force
> from the mild positive static stability starts a very mild oscillation
> that will eventually take you outside the area of positive static
> stability. Once that occurs, dynamic stability is indeed no longer
> important.
>
> Even a plane with comparatively good lateral stability will eventually
> wind up in a spiral once something like turbulence disturbs it. In
> some cases it won't happen - combine a very stable plane with very
> smooth air, and it might fly wings level for a long time. It has
> happened. Also note that the stability improves with lower weight
> (this is true of the longitudinal axis as well - that's why the
> allowable cg range on most light airplanes is wider at lower weights)
> so we do have these stories of planes without pilots flying just fine
> for hours.
>
> I recall one particular sad incident where a Pilatus Porter dropping
> jumpers lost the yoke - it literally came off in the pilot's hands.
> The pilot elected to bail out (which was, IMO, the wrong call - a
> plane can be landed with rudder, throttle, and trim). His parachute
> malfunctioned, and the pilot died. The plane eventually ran out of
> fuel and 'landed' in a field. After a few minor repairs, it was flown
> out.
>
> These things do happen, but they are the exception. Under most normal
> conditions, the combination of neutral or weakly positive static
> stability and negative dynamic stability in the lateral axis will
> eventually put the plane into a spiral.
>
>> Remember, we're dealing here with a dead engine. I'm still going to
>> stick with the spiel :-)) that says with a light GA airplane with
>> positive lateral stability built in with the normal dihedral found on
>> such airplanes and the engine dead, we're going to need a source for
>> an outside the system force strong enough to offset the countering
>> dihedral to any roll input to initiate the roll or yaw (or coupling
>> if you wish) that would end up with the aircraft banked enough to
>> counter the dihedral correcting it back into the normal phugoid I'm
>> expecting.
>
> Sure - but that source will be found in the normal turbulence found on
> most days. There are also additional factors.
>
> First off, any side-by-side airplane with only one person on board is
> going to be slightly out of balance laterally. Any plane with fuel
> feed from a single wing tank, or a less-than-perfect 'both' feed
> (which is most of them) will develop an imbalance. So what we need to
> postulate is a plane that is tandem seating with a header tank (like
> an old-style Champ or maybe a Cub) and then, on a really smooth day,
> it might actually stay wings level.
>
>> If the aircraft has dihedral, it has positive static lateral
>> stability.
>
> That's not necessarily the case. There can be other factors that
> affect stability that would overcome a small amount of dihedral.
> Remember that most airplanes have strong yaw stability, and that
> weakens roll stability because yaw and roll are strongly coupled.
>
>> That's interesting. I never knew that.> > A pretty good primer on
>> stabilit
> y issues can be found here:
>> >http://selair.selkirk.bc.ca/aerodynamics1/Stability/Page5.html
>> I know the site. His stuff is generally very good. I do have some
>> very minor issues with his presentation on a few things.
>
> I also like the site. The particular link includes much of what I
> posted, including the assertion that most light planes left to
> themselves will wind up in a spiral.
>
> Of course as you mentioned elsewhere, this isn't the sort of
> discussion you would have with the average FAA ops inspector. I knew
> a couple who would have appreciated it in Houston. Neither one is
> still with the FAA.
>

Yeah, sadly this is true. I'm just reading up to renew my instructor
cert and have been reading some of the circulars on the FAAs website.
Most of them are excellent, but I was just reading one about stalling
cross controlled, for instance and it's crap.. Having said that, I
suppose it's all good enough for basic private knowledge..
Fortunately, the examiner falls into the pragmatic category.

Bertie

[Bertie the Bunyip[_25_]]

BTW, just about any old ragbag will fly around like a free flight airplane
until they run out of gas. For that matter so will most cessnas and the
like.



Bertie

[More_Flaps]

On Jun 4, 9:38*pm, Michael Ash > wrote:
> In rec.aviation.student Gezellig > wrote:
>
>
>
>
>
> > Michael Ash pretended :
> >> In rec.aviation.student Gezellig > wrote:
> >>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>
> >>>> Joking aside, if your straps were loose enough that you could slump
> >>>> forward, that *would* affect your CG which would in turn affect your
> >>>> trimmed airspeed.
>
> >>>> There's another issue that I just thought of that I don't think anyone has
> >>>> mentioned yet, though. Won't you get into a graveyard (bad terminology for
> >>>> this scenario, as you're already dead) spiral? After all, if you could
> >>>> stay straight and level just by taking your hands off the controls you
> >>>> wouldn't need to fear IMC with no gyroscopic instruments. So it seems that
> >>>> if you start high enough, the correct answer to this question would be
> >>>> whatever the terminal velocity of your fuselage is without its wings. Am I
> >>>> off base here?
>
> >>> You fly until gassless, stall, nose down, then descend too rapidly,
> >>> striking the ground with the wings ripped off. Works for me.
>
> >> You don't stall, because when the engine quits the airplane will start to
> >> descend, maintaining approximately the original airspeed.
>
> > At what point do you expect to lose the wings via "the correct answer
> > to this question would be whatever the terminal velocity of your
> > fuselage is without its wings."?
>
> If you enter a spiral dive as I surmised, the wings fall off either when
> you exceed Vne or when you exceed the maximum loading the wings can
> support, whichever comes first. However it would seem that whether this
> happens or not will depend on the airplane in question.
>

If the plane is in a steady dive at 2x VNE what is the wing loading?
VNE may be set by srface instability (flutter) or perhaps engine
overspeed but is not set by wing loading -that is Va -at least that's
my understanding.

Cheers

[Bertie the Bunyip[_25_]]

More_Flaps > wrote in
:

> On Jun 4, 9:38*pm, Michael Ash > wrote:
>> In rec.aviation.student Gezellig > wrote:
>>
>>
>>
>>
>>
>> > Michael Ash pretended :
>> >> In rec.aviation.student Gezellig > wrote:
>> >>> On Fri, 30 May 2008 01:20:04 -0500, Michael Ash wrote:
>>
>> >>>> Joking aside, if your straps were loose enough that you could
>> >>>> slump forward, that *would* affect your CG which would in turn
>> >>>> affect your trimmed airspeed.
>>
>> >>>> There's another issue that I just thought of that I don't think
>> >>>> anyon
> e has
>> >>>> mentioned yet, though. Won't you get into a graveyard (bad
>> >>>> terminolog
> y for
>> >>>> this scenario, as you're already dead) spiral? After all, if you
>> >>>> coul
> d
>> >>>> stay straight and level just by taking your hands off the
>> >>>> controls yo
> u
>> >>>> wouldn't need to fear IMC with no gyroscopic instruments. So it
>> >>>> seems
> that
>> >>>> if you start high enough, the correct answer to this question
>> >>>> would b
> e
>> >>>> whatever the terminal velocity of your fuselage is without its
>> >>>> wings.
> Am I
>> >>>> off base here?
>>
>> >>> You fly until gassless, stall, nose down, then descend too
>> >>> rapidly, striking the ground with the wings ripped off. Works for
>> >>> me.
>>
>> >> You don't stall, because when the engine quits the airplane will
>> >> start
> to
>> >> descend, maintaining approximately the original airspeed.
>>
>> > At what point do you expect to lose the wings via "the correct
>> > answer to this question would be whatever the terminal velocity of
>> > your fuselage is without its wings."?
>>
>> If you enter a spiral dive as I surmised, the wings fall off either
>> when you exceed Vne or when you exceed the maximum loading the wings
>> can support, whichever comes first. However it would seem that
>> whether this happens or not will depend on the airplane in question.
>>
>
> If the plane is in a steady dive at 2x VNE what is the wing loading?
> VNE may be set by srface instability (flutter) or perhaps engine
> overspeed but is not set by wing loading -that is Va -at least that's
> my understanding.
>

That's right, but the tendency to flutter is exacerbated by load. So, if
you're over redline and you're loading the wing, flutter will occur at a
lower speed than if that surface was unloaded. Flutter is all to do with
the elastic properties of the flight surface, so if it's loaded up
you're exciting the cycle.



Bertie

[Hilton]

Michael wrote:
> I recall one particular sad incident where a Pilatus Porter dropping
> jumpers lost the yoke - it literally came off in the pilot's hands.
> The pilot elected to bail out (which was, IMO, the wrong call - a
> plane can be landed with rudder, throttle, and trim). His parachute
> malfunctioned, and the pilot died.

I'll file this under: "You know you're having a bad day when..."

Hilton

[Gezellig[_2_]]

on 6/4/2008, Dudley Henriques supposed :
> http--soar.wichita.edu-dspace-bitstream-10057-754-1-t05045.pdf.webloc

Linky no worky

[Michael Ash]

In rec.aviation.student More_Flaps > wrote:
>> If you enter a spiral dive as I surmised, the wings fall off either when
>> you exceed Vne or when you exceed the maximum loading the wings can
>> support, whichever comes first. However it would seem that whether this
>> happens or not will depend on the airplane in question.
>
> If the plane is in a steady dive at 2x VNE what is the wing loading?
> VNE may be set by srface instability (flutter) or perhaps engine
> overspeed but is not set by wing loading -that is Va -at least that's
> my understanding.

In a steady *spiral* dive the wing loading will be determined by your bank
angle. I think you may have misread my sentence; I did not mean to imply
that having the wings come off due to excess loading was in any way
related to Vne, it's just due to an ever-tightening spiral, if you
actually get into one and you reach the excess wing loading before you
reach excess speed.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Hilton]

Michael Ash wrote:
> In a steady *spiral* dive the wing loading will be determined by your bank
> angle.

Can you prove that? (mathematically or non-mathematically)

Hilton

[Michael Ash]

In rec.aviation.student Hilton > wrote:
> Michael Ash wrote:
>> In a steady *spiral* dive the wing loading will be determined by your bank
>> angle.
>
> Can you prove that? (mathematically or non-mathematically)

If it's steady, i.e. constant speed, then the loading will be equal to the
arccosine of the bank angle, because you need to generate 1 gee straight
up to counterbalance gravity. This is the same situation as a level turn,
and the math and vectors should be discussed in any introductory book on
flying.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[gatt[_5_]]

Michael Ash wrote:

> The original question specified "trimmed at 110 knots" which implies that
> the autopilot is not engaged.

Correct. The question was asked about two weeks ago by the examiner in
an initial CFI oral. The simple answer that worked was "about 110
knots." I talked to the guy who passed the checkride yesterday. If he
had tried to give a more complicated answer and he was incorrect on
anything he said, he'd have been digging his own hole.

Instead, the examiner moved on and said "I'm a student and I was
supposed to study and prepare for pylon 8's but I didn't do my assigned
homework, so teach me from the beginning."

(My wife's pragmatic response would have been "Come back when you've
completed your assigned homework.")

Fortunately he had a lesson plan prepared on p-8's.

-c

[Michael[_1_]]

On Jun 4, 10:42*am, Dudley Henriques > wrote:
> Below is a very well done white paper on stability by Russel Williams
> that addresses much of what we have been discussing.

The link does not work, and I can't find it through google. Do you
have another link?

> The long and short of it in my opinion is that positive lateral
> stability is present in GA airplanes

As lond as you mean static stability, then yes - weak positive lateral
stability is present in most non-aerobatic (and a few aerobatic) GA
airplanes as long as the displacement from wings-level is small.

> and they will tend to recover from
> the sideslip coupling.

Again, as long as the displacement is small and the lateral trim is
near-perfect.

> Your key point addresses potential disturbances
> that can indeed exceed this recovery tendency.
> I agree totally with you that such a disturbance can exceed positive
> stability tendencies if strong enough.

And I guess my point is that in most cases, these disturbances will be
strong enough, especially in an airplane that can cruise 110 kt. I
think this is something easy enough to prove in most cases. For those
playing along on the home game, try this next time you fly. Do this on
the smoothest possible day you can get.

Set up the plane in cruise at 110 kt. Trim it out as well as you can,
both in pitch, and, if aileron and/or rudder trim is available, in
roll as well. My guess is that most airplanes that can cruise 110 kt
will have aileron or rudder trim available - I can't off the top of my
head think of any certificated exceptions to this (I am sure there is
one).

Let go of the controls. All of them - hands off the yoke/stick and
feet off the rudders - and just sit there. Note how long it takes to
exceed 25 degrees of bank or change heading by 90 degrees.

If in 15 minutes that doesn't happen, smoothly bring the throttle to
idle to simulate fuel exhaustion. Let the plane descend 2000 ft or so
(use carb heat if appropriate). Now see if you are still within 25
degrees of wings level. The reason this matters - generally the
engine is offset just enough that at cruise, you should need no
rudder. On takeoff the left-turning (for CW engines) tendencies are
increased, so you need some right rudder. On a power-off descent, you
need some left rudder. Yaw and roll are coupled. So even if you were
in perfect lateral trim before you went to idle, you're not anymore.

Now I'm willing to bet that at least 9 out of 10 people who try this
will find that the plane won't fly level for 15 minutes without pilot
input, and of the few that do, the engine coming back to idle will
change the yaw enough that more than half the rest will enter a
spiral.

Michael

[K l e i n[_2_]]

On Jun 5, 1:19 pm, Michael > wrote:
> On Jun 4, 10:42 am, Dudley Henriques > wrote:
>
> > Below is a very well done white paper on stability by Russel Williams
> > that addresses much of what we have been discussing.
>
> The link does not work, and I can't find it through google. Do you
> have another link?
>
> > The long and short of it in my opinion is that positive lateral
> > stability is present in GA airplanes
>
> As lond as you mean static stability, then yes - weak positive lateral
> stability is present in most non-aerobatic (and a few aerobatic) GA
> airplanes as long as the displacement from wings-level is small.
>
> > and they will tend to recover from
> > the sideslip coupling.
>
> Again, as long as the displacement is small and the lateral trim is
> near-perfect.
>
> > Your key point addresses potential disturbances
> > that can indeed exceed this recovery tendency.
> > I agree totally with you that such a disturbance can exceed positive
> > stability tendencies if strong enough.
>
> And I guess my point is that in most cases, these disturbances will be
> strong enough, especially in an airplane that can cruise 110 kt. I
> think this is something easy enough to prove in most cases. For those
> playing along on the home game, try this next time you fly. Do this on
> the smoothest possible day you can get.
>
> Set up the plane in cruise at 110 kt. Trim it out as well as you can,
> both in pitch, and, if aileron and/or rudder trim is available, in
> roll as well. My guess is that most airplanes that can cruise 110 kt
> will have aileron or rudder trim available - I can't off the top of my
> head think of any certificated exceptions to this (I am sure there is
> one).
>
> Let go of the controls. All of them - hands off the yoke/stick and
> feet off the rudders - and just sit there. Note how long it takes to
> exceed 25 degrees of bank or change heading by 90 degrees.
>
> If in 15 minutes that doesn't happen, smoothly bring the throttle to
> idle to simulate fuel exhaustion. Let the plane descend 2000 ft or so
> (use carb heat if appropriate). Now see if you are still within 25
> degrees of wings level. The reason this matters - generally the
> engine is offset just enough that at cruise, you should need no
> rudder. On takeoff the left-turning (for CW engines) tendencies are
> increased, so you need some right rudder. On a power-off descent, you
> need some left rudder. Yaw and roll are coupled. So even if you were
> in perfect lateral trim before you went to idle, you're not anymore.
>
> Now I'm willing to bet that at least 9 out of 10 people who try this
> will find that the plane won't fly level for 15 minutes without pilot
> input, and of the few that do, the engine coming back to idle will
> change the yaw enough that more than half the rest will enter a
> spiral.
>
> Michael

If this worked reliably, it would be taught as a standard technique
for inadvertant VFR into IFR excursions. Hey, just throttle to idle,
hands off and wait for VFR to appear. But....this is not what is
taught. Wonder why???

This is curiously close to a technique for spin recovery that is
taught for certain aerobatic airplanes such as the Pitts and the
Extra, called Muller-Beggs. In this method, if you find yourself in a
spin and you can't figure out what to do, then throttle to idle, hands
off the stick and full rudder to counter the apparent yaw you see
directly out the front, wait patiently for the spin to stop, then
neutralize rudder and recover from the dive. This does NOT work for
all aerobatic aircraft. One I'm personally familiar with that does
not work is the Yak-54.

K l e i n

[Hilton]

Michael Ash wrote:
> Hilton wrote:
>> Michael Ash wrote:
>>> In a steady *spiral* dive the wing loading will be determined by your
>>> bank
>>> angle.
>>
>> Can you prove that? (mathematically or non-mathematically)
>
> If it's steady, i.e. constant speed, then the loading will be equal to the
> arccosine of the bank angle, because you need to generate 1 gee straight
> up to counterbalance gravity. This is the same situation as a level turn,
> and the math and vectors should be discussed in any introductory book on
> flying.

Your 'proof' above is almost correct for *level* flight (it ignores attitude
etc, but I don't want to knit pick), however, it is not appropriate at all
in a spiral even if the aircraft is at a constant speed. In a spiral, there
is a non-zero component of vertical drag, therefore less vertical lift is
required. However, your lift vector is now at an angle to the vertical.
You cannot ignore these. Therefore the wing loading is also a function of
the coefficient of drag, and perhaps other things, but clearly not only
determined by your bank angle.

Hilton

[Michael Ash]

In rec.aviation.student K l e i n > wrote:
> If this worked reliably, it would be taught as a standard technique
> for inadvertant VFR into IFR excursions. Hey, just throttle to idle,
> hands off and wait for VFR to appear. But....this is not what is
> taught. Wonder why???

One reason that comes to mind is that you have no guarantee that the
ceiling under your IMC condition is high enough to allow for recovery.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Bertie the Bunyip[_25_]]

Michael Ash > wrote in news:1212717258.920305
@web1.segnet.com:

> In rec.aviation.student K l e i n > wrote:
>> If this worked reliably, it would be taught as a standard technique
>> for inadvertant VFR into IFR excursions. Hey, just throttle to idle,
>> hands off and wait for VFR to appear. But....this is not what is
>> taught. Wonder why???
>
> One reason that comes to mind is that you have no guarantee that the
> ceiling under your IMC condition is high enough to allow for recovery.
>

Well, "inadvertant flight into IMC" is almost always a push on regardless
scenario where the pilot gets lower and lower, often in inhospitable
terrain, so it'd be kind of useless in that anyway.


Bertie

[Jay Maynard]

On 2008-06-06, Michael Ash > wrote:
> In rec.aviation.student K l e i n > wrote:
>> If this worked reliably, it would be taught as a standard technique
>> for inadvertant VFR into IFR excursions. Hey, just throttle to idle,
>> hands off and wait for VFR to appear. But....this is not what is
>> taught. Wonder why???
> One reason that comes to mind is that you have no guarantee that the
> ceiling under your IMC condition is high enough to allow for recovery.

....especially if there's cumulo-granite or cumulo-steel inside.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (ordered 17 March, delivery 10 June)

[Michael Ash]

In rec.aviation.student Jay Maynard > wrote:
> On 2008-06-06, Michael Ash > wrote:
>> In rec.aviation.student K l e i n > wrote:
>>> If this worked reliably, it would be taught as a standard technique
>>> for inadvertant VFR into IFR excursions. Hey, just throttle to idle,
>>> hands off and wait for VFR to appear. But....this is not what is
>>> taught. Wonder why???
>> One reason that comes to mind is that you have no guarantee that the
>> ceiling under your IMC condition is high enough to allow for recovery.
>
> ...especially if there's cumulo-granite or cumulo-steel inside.

Just so.

Reading my own post it occurs to me that "IMC condition" is one of those
redundant uses of acronyms, like "ATM machine" or "PIN number". My
apologies for any annoyance this may have caused. :)

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

[Michael[_1_]]

On Jun 5, 4:01*pm, K l e i n > wrote:
> If this worked reliably, it would be taught as a standard technique
> for inadvertant VFR into IFR excursions. *Hey, just throttle to idle,
> hands off and wait for VFR to appear. *But....this is not what is
> taught. *Wonder why???

Well, two reasons. One, because there is no guarantee that you will
reach stability in a bank without exceeding Vne (and in fact in many
airplanes you will not - wings or tail will come off). Two, because
recovery from a spiral dive actually takes a fair amount of altitude,
and trying to do it quickly will likely break something as you will be
well above Va.

> This is curiously close to a technique for spin recovery that is
> taught for certain aerobatic airplanes such as the Pitts and the
> Extra, called Muller-Beggs.

Well, OK - but it's not a technique at all. It is simply a
demostration that the airplane will not remain wings level at trim
speed without pilot input for very long, expecially in the event of
engine failure. Quite the contrary, an active recovery will most
likely be necessary.

If the demostration is wrong, then the plane WILL remain wings level
(the way a ram-air parachute will). Now THAT would be useful for
inadvertent IMC encounters. Just tell people to let go of the
controls, and the plane will fly out of it. In fact, that is exactly
what parachutists do if they inadvertently encounter a cloud.

Michael

[Bertie the Bunyip[_25_]]

Michael > wrote in news:7dad14f5-8015-
:


> If the demostration is wrong, then the plane WILL remain wings level
> (the way a ram-air parachute will). Now THAT would be useful for
> inadvertent IMC encounters. Just tell people to let go of the
> controls, and the plane will fly out of it. In fact, that is exactly
> what parachutists do if they inadvertently encounter a cloud.

Some of them will undoubtedly do it, but most prolly won't.
There is one that probably would save your bacon if you had either an
engine failure or you got caught in IMC down to the ground.
It's the French Rallye and it will sit in a semi stalled attitude power on
or off as long as you hold the stick back with a relativley low rate of
descent. Some people call it the "Tin Parachute" I've flown a couple of the
small engined ones in Yerp and they're pretty marginal in climb, though..

Bertie

[Robert M. Gary]

On May 30, 9:00*am, "F. Baum" > wrote:
> On May 29, 9:54*am, "Robert M. Gary" > wrote:
>
>
>
> > Huh, that's not right. There is nothing in the PTS that says you get
> > to skip the FOI stuff just because you have an AGI. The only thing you
> > get to skip is showing your FOI exam results. I had my AGI and
> > probably spent 5 hours of my CFI oral on FOI stuff.
>
> Is there anything in the PTS that says you have to be retested on
> previously completed material ?

Yes, the PTS says you have to cover FOI during the oral even if you
have the AGI certificate. Actually the PTS does not allow you to skip
*any* part of the initial CFI practical test just because you have the
AGI.
Remember, there is no practical for the AGI, you just walk into the
FSDO (after making an appointment, going through security, signing in,
swearing you're not a terrorist) and show them your AGI and FOI exams.

-Robert

[Bertie the Bunyip[_25_]]

"Robert M. Gary" > wrote in news:36ec67fe-ff3e-4978-a0ef-
:

> On May 30, 9:00*am, "F. Baum" > wrote:
>> On May 29, 9:54*am, "Robert M. Gary" > wrote:
>>
>>
>>
>> > Huh, that's not right. There is nothing in the PTS that says you get
>> > to skip the FOI stuff just because you have an AGI. The only thing you
>> > get to skip is showing your FOI exam results. I had my AGI and
>> > probably spent 5 hours of my CFI oral on FOI stuff.
>>
>> Is there anything in the PTS that says you have to be retested on
>> previously completed material ?
>
> Yes, the PTS says you have to cover FOI during the oral even if you
> have the AGI certificate. Actually the PTS does not allow you to skip
> *any* part of the initial CFI practical test just because you have the
> AGI.
> Remember, there is no practical for the AGI, you just walk into the
> FSDO (after making an appointment, going through security, signing in,
> swearing you're not a terrorist) and show them your AGI and FOI exams.
>
> -Robert

I'm renewing mine next week . He's not going to ask me what all those
acronyms mena is he?


Bertie

[Marty Shapiro]

Bertie the Bunyip > wrote in
:

> Michael > wrote in
> news:7dad14f5-8015-
> :
>
>
>> If the demostration is wrong, then the plane WILL remain wings level
>> (the way a ram-air parachute will). Now THAT would be useful for
>> inadvertent IMC encounters. Just tell people to let go of the
>> controls, and the plane will fly out of it. In fact, that is exactly
>> what parachutists do if they inadvertently encounter a cloud.
>
> Some of them will undoubtedly do it, but most prolly won't.
> There is one that probably would save your bacon if you had either an
> engine failure or you got caught in IMC down to the ground.
> It's the French Rallye and it will sit in a semi stalled attitude
> power on or off as long as you hold the stick back with a relativley
> low rate of descent. Some people call it the "Tin Parachute" I've
> flown a couple of the small engined ones in Yerp and they're pretty
> marginal in climb, though..
>
> Bertie
>

Move up to the Rallye 235. Not marginal in climb at all.

At power off, yoke full back, the 235's nose bobbles (more like light
buffet) very slightly on the horizon whle you descend at just over 1,000
fpm in this nose level attitude.

--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)

[Bertie the Bunyip[_25_]]

Marty Shapiro > wrote in
:

>
>>
>
> Move up to the Rallye 235. Not marginal in climb at all.

Yeah, so I believe. Not very fast, though, is it?
>
> At power off, yoke full back, the 235's nose bobbles (more like light
> buffet) very slightly on the horizon whle you descend at just over 1,000
> fpm in this nose level attitude.
>

You'd probably walk away formit, but it would hurt! You're forward speed is
pretty low in this flight regime then, eh? Less than 40?

Bertie

[Marty Shapiro]

Bertie the Bunyip > wrote in
:

> Marty Shapiro > wrote in
> :
>
>>
>>>
>>
>> Move up to the Rallye 235. Not marginal in climb at all.
>
> Yeah, so I believe. Not very fast, though, is it?

No. Top speed is 152 MPH (131 kt). The automatic leading edge slats and
fixed gear add quite a bit of drag.

With half tanks, just me in the aircraft, 1/2 flaps, and a cool day (10 C)
I can be almost 1,000' AGL by the end of a 3,100' runway if I hold Vx all
the way.

(Fowler flaps. 1/2 has them fully extended but only 10 degrees or so
down.)

>>
>> At power off, yoke full back, the 235's nose bobbles (more like light
>> buffet) very slightly on the horizon whle you descend at just over
>> 1,000 fpm in this nose level attitude.
>>
>
> You'd probably walk away formit, but it would hurt! You're forward
> speed is pretty low in this flight regime then, eh? Less than 40?

About 35 MPH.

>
> Bertie
>



--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)

[Bertie the Bunyip[_25_]]

Marty Shapiro > wrote in
:

> Bertie the Bunyip > wrote in
> :
>
>> Marty Shapiro > wrote in
>> :
>>
>>>
>>>>
>>>
>>> Move up to the Rallye 235. Not marginal in climb at all.
>>
>> Yeah, so I believe. Not very fast, though, is it?
>
> No. Top speed is 152 MPH (131 kt). The automatic leading edge slats
> and fixed gear add quite a bit of drag.


Really? I thought they were a good bit slower than that.
>
> With half tanks, just me in the aircraft, 1/2 flaps, and a cool day
> (10 C) I can be almost 1,000' AGL by the end of a 3,100' runway if I
> hold Vx all the way.
>

Good bush airplane alright. Rare enough nowadays too, since most seem to
have corroded away.
Is it a French one or a Polish one?
I saw a Taildragger one recently in Spain. That'd probably be quite a
useful machine..



> (Fowler flaps. 1/2 has them fully extended but only 10 degrees or so
> down.)
>
>>>
>>> At power off, yoke full back, the 235's nose bobbles (more like
>>> light buffet) very slightly on the horizon whle you descend at just
>>> over 1,000 fpm in this nose level attitude.

>>>
>>
>> You'd probably walk away formit, but it would hurt! You're forward
>> speed is pretty low in this flight regime then, eh? Less than 40?
>
> About 35 MPH.

That's pretty good OK.


>
>

[Marty Shapiro]

Bertie the Bunyip > wrote in
:

> Marty Shapiro > wrote in
> :
>
>> Bertie the Bunyip > wrote in
>> :
>>
>>> Marty Shapiro > wrote in
>>> :
>>>
>>>>
>>>>>
>>>>
>>>> Move up to the Rallye 235. Not marginal in climb at all.
>>>
>>> Yeah, so I believe. Not very fast, though, is it?
>>
>> No. Top speed is 152 MPH (131 kt). The automatic leading edge slats
>> and fixed gear add quite a bit of drag.
>
>
> Really? I thought they were a good bit slower than that.

The light airframe models are slower.

Rallye's have multiple models. The "light" airframes were mainly 2 seat,
stick, and engines from 100 HP through 150 HP (Rolls Royce, Continental,
Lycoming). The 180 HP was a 4 seater and you could order with stick or
yoke. Lycoming engine.

The "heavy" airframes were the Minerva (Franklin 220 HP engine) and the
Rallye GT aka 235E (Lycoming O-540-B4B5 235 HP). All the "heavies" had 4
seats, yokes, and 2 hard points on each wing.

The 235C was a tail dragger version of the 235E. The 235's also came with
a factory opiton of a glider tow kit.


>>
>> With half tanks, just me in the aircraft, 1/2 flaps, and a cool day
>> (10 C) I can be almost 1,000' AGL by the end of a 3,100' runway if I
>> hold Vx all the way.
>>
>
> Good bush airplane alright. Rare enough nowadays too, since most seem to
> have corroded away.

Only the 235C would be a good bush airplane. The prop clearance on the
trike is at best 2". It does have a decent payload capacity. Empty weight
is 1,535 lbs and MTOW is 2,645 lbs. Max landing weight is 2,513, so plan
on burning 22 gals if you take off at max weight.

The last time I looked, there was something like slightly less than 100
Rallye's of all models (both French and Polish) on the FAA registry.

> Is it a French one or a Polish one?

French. To my knowledge, PZL Koliber only sold a version of the 150. They
were working on a version of the 235 but I'm not aware of it ever being
released.

The original Rallye's were made by Moraine-Soulnier, which was eventually
merged into SOCATA, which is now part of EADS. SOCATA licensed it to PZL,
which used it to produce the Koliber 150. I seem to remember reading that
SOCATA has bought the license back from PZL.


> I saw a Taildragger one recently in Spain. That'd probably be quite a
> useful machine..
>
>
>
>> (Fowler flaps. 1/2 has them fully extended but only 10 degrees or so
>> down.)
>>
>>>>
>>>> At power off, yoke full back, the 235's nose bobbles (more like
>>>> light buffet) very slightly on the horizon whle you descend at just
>>>> over 1,000 fpm in this nose level attitude.
>
>>>>
>>>
>>> You'd probably walk away formit, but it would hurt! You're forward
>>> speed is pretty low in this flight regime then, eh? Less than 40?
>>
>> About 35 MPH.
>
> That's pretty good OK.
>
>
The design is STOL. Huge oversized control surfaces. In a power off stall
configuration, you can still steer with just the ailerons, although you
will get a dramatic adverse yaw demonstration.

We have a 300' displaced threshold at my home field. I can pop the mains
off before the landing threshold and well below the white arc. Yes, it
will wallow in ground effect a bit, but then settles right down and climbs.
With a little concentration, you can land in 500' and just light brakes.

Great visibility from the cockpit. The sliding canopy comes down almost to
your waist. The first time I did a 45 degree bank it seemed that I was
going to slide right out of the cockpit. You can also fly with the canopy
open, although you do have speed restrictions based on how far it is open.
Up to 4" and there are no restrictions. Fully open you're limited to 93
MPH.

--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)