Rolling a 172 - or not

[Scott Lowrey]

If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
while maintaining neutral rudder, what will happen if I don't
neutralize the ailerons?

I'm picturing the plane rolling on to its back while losing altitude
and either completing the roll (doubtful) or stalling into a dive and
recovering in the other direction , right side up. (BTW, that's a
split-S, isn't it?)

I wouldn't anticipate a spin unless some serious rudder was cranked in
the direction of the roll.

-Scott "I feel like REALLY flying today" Lowrey

[T-Boy]

In article >,
says...
> If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
> while maintaining neutral rudder, what will happen if I don't
> neutralize the ailerons?
>
> I'm picturing the plane rolling on to its back while losing altitude
> and either completing the roll (doubtful) or stalling into a dive and
> recovering in the other direction , right side up. (BTW, that's a
> split-S, isn't it?)
>
> I wouldn't anticipate a spin unless some serious rudder was cranked in
> the direction of the roll.
>
> -Scott "I feel like REALLY flying today" Lowrey

With an attitude like that, i'm not sure you should :) OK, seriously..
I think you'll find you'll roll over and then, keep on going, coming
back to a level, but pointing very much downwards by now, and your
airspeed will be well past max. To complete such a roll safely: get the
nose well up first (30/40 degreees) - otherwise you'll overspeed, and:
do these things in an aerobatically approved a/c with an instructor -
you'll: a) not bust the plane, b) have a chitload of fun!


--
Duncan

[Maule Driver]

If the elevator is kept neutral, your nose will drop throughout the roll -
no stall. You'll probably be over redline by the finish.

What actually happens as many acro students will attest to (and many dum dum
wanna bes who scare the living bejezus out of themselves) is that upon
approaching inverted and while noting the sudden nose drop, ones natural
response is to pullllllll. That's an inadvertant split S. Very easy and
natural to do. Almost unavoidable for the untrained. Good way to take the
wings off.

That's why instruction is so valuable. Learning to start nose up and push a
bit when you otherwise will want to pull will result in a passable roll of
sorts. A little acro skill may give you what you need to push and roll if
you ever find yourself upside down due to wake turb or something.

It's stupid to do in a 172 though. Same for a snap. My Maule will never
see one while I'm in the seat.

And a hex on CFIs that like to flip it to 'impress' their impressionable
students.

"Scott Lowrey" > wrote in message
om...
> If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
> while maintaining neutral rudder, what will happen if I don't
> neutralize the ailerons?
>
> I'm picturing the plane rolling on to its back while losing altitude
> and either completing the roll (doubtful) or stalling into a dive and
> recovering in the other direction , right side up. (BTW, that's a
> split-S, isn't it?)
>
> I wouldn't anticipate a spin unless some serious rudder was cranked in
> the direction of the roll.
>
> -Scott "I feel like REALLY flying today" Lowrey

[Wayne]

It's not going to spin unless it's cross controlled, and stalled. Nose
low and excess speed is likely to be the result. Vne and overspeed of the
engine and both bad things. It's like to see that on flight sim.
Wayne

> I wouldn't anticipate a spin unless some serious rudder was cranked in
> the direction of the roll.
>
> -Scott "I feel like REALLY flying today" Lowrey

[Ron Natalie]

"Wayne" > wrote in message ...
> It's not going to spin unless it's cross controlled, and stalled. Nose
> low and excess speed is likely to be the result. Vne and overspeed of the
> engine and both bad things. It's like to see that on flight sim.

Crosscontrolling is not necessary to instigate a spin (as a matter of fact
many will argue it is less likely).

[Timothy Oneal]

Dont forget that the fuel is gravity fed to the engine. Stay upside down
too long and your gonna lose power.....


Tim

"Scott Lowrey" > wrote in message
om...
> If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
> while maintaining neutral rudder, what will happen if I don't
> neutralize the ailerons?
>
> I'm picturing the plane rolling on to its back while losing altitude
> and either completing the roll (doubtful) or stalling into a dive and
> recovering in the other direction , right side up. (BTW, that's a
> split-S, isn't it?)
>
> I wouldn't anticipate a spin unless some serious rudder was cranked in
> the direction of the roll.
>
> -Scott "I feel like REALLY flying today" Lowrey

[Eclipsme]

Yes, and oil too!

Harvey

"Timothy Oneal" > wrote in message
...
> Dont forget that the fuel is gravity fed to the engine. Stay upside down
> too long and your gonna lose power.....
>
>
> Tim
>
> "Scott Lowrey" > wrote in message
> om...
> > If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
> > while maintaining neutral rudder, what will happen if I don't
> > neutralize the ailerons?
> >
> > I'm picturing the plane rolling on to its back while losing altitude
> > and either completing the roll (doubtful) or stalling into a dive and
> > recovering in the other direction , right side up. (BTW, that's a
> > split-S, isn't it?)
> >
> > I wouldn't anticipate a spin unless some serious rudder was cranked in
> > the direction of the roll.
> >
> > -Scott "I feel like REALLY flying today" Lowrey
>
>

[Orval Fairbairn]

In article >,
"Eclipsme" > wrote:

> Yes, and oil too!
>
> Harvey
>
> "Timothy Oneal" > wrote in message
> ...
> > Dont forget that the fuel is gravity fed to the engine. Stay upside down
> > too long and your gonna lose power.....
> >


Not if you maintain positive G all the way around (as in aileron roll).
Of course, a 172 handles about like a truck! It would ba similar to
having sex with Roseanne Barr!





> >
> > "Scott Lowrey" > wrote in message
> > om...
> > > If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
> > > while maintaining neutral rudder, what will happen if I don't
> > > neutralize the ailerons?
> > >
> > > I'm picturing the plane rolling on to its back while losing altitude
> > > and either completing the roll (doubtful) or stalling into a dive and
> > > recovering in the other direction , right side up. (BTW, that's a
> > > split-S, isn't it?)
> > >
> > > I wouldn't anticipate a spin unless some serious rudder was cranked in
> > > the direction of the roll.
> > >
> > > -Scott "I feel like REALLY flying today" Lowrey
> >
> >
>
>

[mike regish]

Ewwwwww...

mike regish

"Orval Fairbairn" > wrote in message
news:orfairbairn_spam_sucks-

> It would ba similar to
> having sex with Roseanne Barr!
>
>
>
>
>

[vincent p. norris]

>Not if you maintain positive G all the way around (as in aileron roll).

You don't have positive G all the way around in an aileron roll.

To maintain positive G, you need a barrel roll.

vince norris

[Orval Fairbairn]

In article >,
vincent p. norris > wrote:

> >Not if you maintain positive G all the way around (as in aileron roll).
>
> You don't have positive G all the way around in an aileron roll.
>
> To maintain positive G, you need a barrel roll.
>
> vince norris

You are thinking slow roll -- you DO maintain positive G in an aileron
roll.

[Hamish Reid]

In article >,
vincent p. norris > wrote:

> >Not if you maintain positive G all the way around (as in aileron roll).
>
> You don't have positive G all the way around in an aileron roll.

In a properly done aileron roll you certainly do...

> To maintain positive G, you need a barrel roll.

Or an aileron roll. Were you thinking of a slow roll?

Hamish

[Maule Driver]

"Hamish Reid" >
> >
> > You don't have positive G all the way around in an aileron roll.
>
> In a properly done aileron roll you certainly do...
>
> > To maintain positive G, you need a barrel roll.
>
> Or an aileron roll. Were you thinking of a slow roll?
>
I'm confused. Please describe a properly done aileron roll.

I have some glider acro training and lot's of RC model acro. I think of
axial rolls and barrel rolls. Both benefit from aileron, elevator and
rudder input. I've thought that aileron roles are synonymous with axial and
slow rolls synonymous with barrel rolls. But there is a lot of RC legacy
stuff in my understanding.

[vincent p. norris]

>> You don't have positive G all the way around in an aileron roll.
>
>In a properly done aileron roll you certainly do...

>Were you thinking of a slow roll?

I know the diffference between a slow roll and an aileron roll.

If you think you maintain positive G in an aileron roll,

(1). Take along a bottle of water and a drinking glass next time you
fly.

(2). Fill the glass with water and place it atop the instrument
panel.

(3). Do an aileron roll.

vince norris

[Hamish Reid]

In article >,
"Maule Driver" > wrote:

> "Hamish Reid" >
> > >
> > > You don't have positive G all the way around in an aileron roll.
> >
> > In a properly done aileron roll you certainly do...
> >
> > > To maintain positive G, you need a barrel roll.
> >
> > Or an aileron roll. Were you thinking of a slow roll?
> >
> I'm confused. Please describe a properly done aileron roll.

Check out <http://acro.harvard.edu/ACRO/acro_figures.html#rolls> for a
brief description.

> I have some glider acro training and lot's of RC model acro. I think of
> axial rolls and barrel rolls. Both benefit from aileron, elevator and
> rudder input. I've thought that aileron roles are synonymous with axial and
> slow rolls synonymous with barrel rolls.

Hmmm. Aileron rolls are closer to barrell rolls, slow rolls with axial
rolls. In fact, a slow roll is a roll around the longitudinal axis; an
aileron roll does not keep the longitudinal axis of the plane straight
ahead...

Hamish

[Hamish Reid]

In article >,
vincent p. norris > wrote:

> >> You don't have positive G all the way around in an aileron roll.
> >
> >In a properly done aileron roll you certainly do...
>
> >Were you thinking of a slow roll?
>
> I know the diffference between a slow roll and an aileron roll.

OK... but you contradict texts such as Szyurovy and Goulian, not to
mention basic experience.

> If you think you maintain positive G in an aileron roll,
>
> (1). Take along a bottle of water and a drinking glass next time you
> fly.
>
> (2). Fill the glass with water and place it atop the instrument
> panel.
>
> (3). Do an aileron roll.

And then what...? Does the water spill because the aileron roll is *not*
a positive-G maneuver, or because the forces on it are not balanced
laterally or longitudinally? (I can't do the experiement because there's
nowhere to put the glass in the plane I fly).

Or do it in a Cessna Aerobat -- which requires a positive G force to
keep the oil and fuel running. I can get the engine to stutter in a
second or two in a slow roll (more like a slowish roll in an Aerobat,
but never mind :-)); not in a properly-done aileron roll. That's
because, unlike a slow roll (where at the 180 degree point we typically
get mild negative G's), we keep positive G's on the plane at all points
in the aileron roll.

Much of the whole point of an aileron roll is to maintain a positive G
force on the plane. It's the easiest and most pleasant (for passengers)
of the four main rolls. To quote S & G (p50 in my edition): "On its
ballistic, corkscrew-like flight path, the airframe continuously
experiences normal acceleration, maintaining light, positive G all the
way around the aileron roll". Not that I take much notice of texts, but
there it is....

You weren't thinking of a "1G" maneuver were you, rather than "positive
G"?

Hamish

[Robert Moore]

"Maule Driver" > wrote
> I have some glider acro training and lot's of RC model acro. I
> think of axial rolls and barrel rolls. Both benefit from
> aileron, elevator and rudder input. I've thought that aileron
> roles are synonymous with axial and slow rolls synonymous with
> barrel rolls.

From the following web site about aerobatics:

http://acro.harvard.edu/IAC/faq_aerobatics.html

Aileron Rolls
Aileron rolls are flown with the rudder and elevator in the neutral
position during the roll. The aileron is fully deflected in the
direction of the roll. This is the easiest of the rolls to fly.
The aileron roll is started by pulling the nose up to 20 - 30 degrees
above the horizon. The elevator is then neutralized and the aileron
fully deflected in the direction of the roll. The controls are
maintained in that position till the roll is completed. After the
roll is completed the nose is usually 20 - 30 degrees below the
horizon.

The aileron roll is not a competition maneuver.


Slow Rolls
Slow rolls have to be flown normally on a straight line (exception is
the avalanche). The roll rate has to be constant and the longitudinal
axis of the plane has to go straight. This requires constantly
changing rudder and elevator control inputs throughout the roll.
Hesitation or point rolls include stops at certain roll angles. The
number on the base of the roll symbol describes the number of points
the roll would have if it were a 360 degree roll. Allowed are 2
point, 4 point and 8 point rolls. The fraction on the arrow of the
roll symbol describes what fraction of a full roll is to be executed.
If no points are specified, rolling is done without hesitations. If
no fraction is specified, a roll symbol that starts at the line
specifies a half roll (see description of the Immelman). A roll
symbol that crosses the line specifies a full roll (first figure).
The second figure shows the symbol for 2 points of a 4 point roll
(adding up to half a roll) from upright to inverted flight.

Snap Rolls
Snap or flick rolls also have to be flown normally on a straight
line. A snap roll is similar to a horizontal spin. It is an
autorotation with one wing stalled. In the regular snap, the plane
has to be stalled by applying positive g forces. In an outside snap,
the plane is stalled by applying negative g. In both cases rudder is
then used to start autorotation just like in a spin.

Barrel Roll
The Barrel Roll is a not competition maneuver. I The barrel roll is a
combination between a loop and a roll. You complete one loop while
completing one roll at the same time. The flight path during a barrel
roll has the shape of a horizontal cork screw. Imagine a big barrel,
with the airplanes wheels rolling along the inside of the barrel in a
cork screw path. During a barrel roll, the pilot experiences always
positive G's. The maximum is about 2.5 to 3 G, the minimum about 0.5
G.

Bob Moore

[Big John]

Lets kill this thread right now.

1. A 'barrel roll' is a roll where (if done properly) you as a
passenger, with your eyes closed, can not tell you did a roll. The
ball stays centered and if one 'G' is maintained, it feels like
straight and level flight. Starting nose position and of course air
speed varies between underpoweed GA aircraft and super sonic Fghters.

2. A 'slow roll' (point roll) is done with the nose pointing at a
single point (normally picked out o horizon) all the way around. In
Fighters, can be done from straigaht and level flight. Most GA
aircraft require a little airspeed above cruise. To do you raise the
nose above the point on the horizion and start a roll with aileron. As
you continue the roll you feed in top rudder to hold nose up and
adjust the elevator to keep nose on the point. As roll continues you
feed in down elevator (here's your negative G's) to hold the nose up
and on the point while relaxing the top rudder input. As roll
continues you again feed in top rudder (opposite rudder) to hold nose
up on point and take off down elevator holding nose on point. After
passing the 270 degree position, you start removing top rudder and
adjust the elevator to keep nose on point. As you come back out
straight and level all controls are again in neutral. Negatiave "G's"
are of course pulled when on your back. Roll can be relatitivly slow
or rapid as long as nose can be held on a point going around.

3. An aileron roll is just laying the aileron over (normally full
aileron) and letting bird roll. Depending on type of aircraft (fighter
or GA) the nose makes a circle around a point. Fighters can do at
cruise with little or no nose above the horizon. GA requires a start
with the nose above the horizon due to slower rate of roll and bird
ending up nose low because no other control input to hold nose up
while inverted is used

There are also a few fine points the experts use that I have not
covered but above are the basics.

Been there done that for longer (65 years) than BOb has been flying.
:o)


Big John.


On 4 Nov 2003 12:06:03 -0800, (Scott Lowrey)
wrote:

>If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
>while maintaining neutral rudder, what will happen if I don't
>neutralize the ailerons?
>
>I'm picturing the plane rolling on to its back while losing altitude
>and either completing the roll (doubtful) or stalling into a dive and
>recovering in the other direction , right side up. (BTW, that's a
>split-S, isn't it?)

----clip----

[Robert Moore]

Big John > wrote
> 1. A 'barrel roll' is a roll where (if done properly) you as a
> passenger, with your eyes closed, can not tell you did a roll.
> The ball stays centered and if one 'G' is maintained, it feels
> like straight and level flight. Starting nose position and of
> course air speed varies between underpoweed GA aircraft and
> super sonic Fghters.

Hey John, I didn't make-up that post, it came straight from:

http://acro.harvard.edu

The Barrel Roll is a not competition maneuver. The barrel roll is a
combination between
a loop and a roll. You complete one loop while completing one roll at
the same time.
The flight path during a barrel roll has the shape of a horizontal
cork screw. Imagine a big
barrel, with the airplanes wheels rolling along the inside of the
barrel in a cork screw path.
During a barrel roll, the pilot experiences always positive G's. The
maximum is about 2.5 to
3 G, the minimum about 0.5 G.

Care to give us a reference for your definition?

Bob

[Happy Dog]

"vincent p. norris" > wrote in message
> >> You don't have positive G all the way around in an aileron roll.
> >
> >In a properly done aileron roll you certainly do...
>
> >Were you thinking of a slow roll?
>
> I know the diffference between a slow roll and an aileron roll.
>
> If you think you maintain positive G in an aileron roll,
>
> (1). Take along a bottle of water and a drinking glass next time you
> fly.
>
> (2). Fill the glass with water and place it atop the instrument
> panel.
>
> (3). Do an aileron roll.

Which proves what? Place a glass of water atop the instrument panel and
execute a steep turn. It won't stay there, Are you saying that a steep
turn isn't a positive G manoeuvre? You haven't thought this through...

le moo

[Dave Stadt]

"Happy Dog" > wrote in message
.. .
> "vincent p. norris" > wrote in message
> > >> You don't have positive G all the way around in an aileron roll.
> > >
> > >In a properly done aileron roll you certainly do...
> >
> > >Were you thinking of a slow roll?
> >
> > I know the diffference between a slow roll and an aileron roll.
> >
> > If you think you maintain positive G in an aileron roll,
> >
> > (1). Take along a bottle of water and a drinking glass next time you
> > fly.
> >
> > (2). Fill the glass with water and place it atop the instrument
> > panel.
> >
> > (3). Do an aileron roll.
>
> Which proves what? Place a glass of water atop the instrument panel and
> execute a steep turn. It won't stay there, Are you saying that a steep
> turn isn't a positive G manoeuvre? You haven't thought this through...
>
> le moo


If you stay coordinated it certainly will stay. Ever see the video of
Hoover pouring a glass of water while doing a roll.

[Robert Moore]

"Happy Dog" > wrote
> Which proves what? Place a glass of water atop the instrument
> panel and execute a steep turn. It won't stay there,

It should!!! If not, you're not using the controls properly.
I teach my students to execute co-ordinated steep turns,
doesn't everyone do it that way???

Bob Moore
ATP CFI

[Robert Moore]

Big John > wrote
> 1. A 'barrel roll' is a roll where (if done properly) you as a
> passenger, with your eyes closed, can not tell you did a roll.
> The ball stays centered and if one 'G' is maintained, it feels
> like straight and level flight. Starting nose position and of
> course air speed varies between underpoweed GA aircraft and
> super sonic Fghters.
> There are also a few fine points the experts use that I have not
> covered but above are the basics.
>
> Been there done that for longer (65 years) than BOb has been
> flying. :o)

I have e-mailed BigJohn and posted at:

alt.binaries.pictures.aviation

a scan from William Kershner's book, The Flight Instructor's
Manual, in which he describes the barrel roll as an acrobatic
maneuver. You probably know that Mr. Kershner is one of the most
respected names in the flight training field, having authored
several books on the subject. Not as funny as Machado, but he has
been around for a much longer period of time.
I haven't scanned and OCRed the text because I think that the
picture is self-explanitory, but if it would help, I will do the
page of text describing the barrel roll.

Note that as mentioned in my previous post quoting from:

http://acro.harvard.edu

that one cannot maintain "one G" in a barrel roll since it involves
both a loop and a roll. In order to perform the loop portion, one
must pull at least 3-3.5 Gs in the pull-up and a similiar force in
the pull-out. While inverted, the g-force drops to .5-1 g as in a
normal loop.

I readily conceed that Big John as been around a bit longer than I,
but by the the time that I flew in the military, we were learning
to fly in "airplanes", not "birds". :-) :-)

Bob

[Happy Dog]

"Dave Stadt" > wrote in message

> > > (2). Fill the glass with water and place it atop the instrument
> > > panel.
> > >
> > > (3). Do an aileron roll.
> >
> > Which proves what? Place a glass of water atop the instrument panel and
> > execute a steep turn. It won't stay there, Are you saying that a steep
> > turn isn't a positive G manoeuvre? You haven't thought this through...
> >
>
> If you stay coordinated it certainly will stay. Ever see the video of
> Hoover pouring a glass of water while doing a roll.

If you stay *perfectly* coordinated. I would have no problem demonstrating
an aileron roll with a cup of MacDonald's most dangerous firmly secured in
my lap. (Filled to no more than a couple inches below the brim.) I have a
key fob that I sometimes watch during aerobatic manoeuvres. It doesn't move
much during coordinated 1G stuff. But it moves a bit.

le moo

[Happy Dog]

"Robert Moore" > wrote in message
. 8...
> "Happy Dog" > wrote
> > Which proves what? Place a glass of water atop the instrument
> > panel and execute a steep turn. It won't stay there,
>
> It should!!! If not, you're not using the controls properly.
> I teach my students to execute co-ordinated steep turns,
> doesn't everyone do it that way???

The point is that it will likely move, not because there is a negative G
situation, but because it takes very little lateral G force to knock it off.
Have you actually tried this? Three times in a row?

le moo

[Hamish Reid]

In article >,
Big John > wrote:

[...]

> 3. An aileron roll is just laying the aileron over (normally full
> aileron) and letting bird roll. Depending on type of aircraft (fighter
> or GA) the nose makes a circle around a point. Fighters can do at
> cruise with little or no nose above the horizon. GA requires a start
> with the nose above the horizon due to slower rate of roll and bird
> ending up nose low because no other control input to hold nose up
> while inverted is used

The question for me -- and what prompted my earlier posting(s) -- is
whether it's possible to do a standard aileron roll and get negative G's
(or non-positive G's, to be precise). The puny GA planes I fly all have
positive G forces all the way around an aileron roll (unless you do
something funny with elevator and / or rudder), but is that true of all
aircraft?

Hamish

[Big John]

Robert

You talk about doing a LOOP in association with a roll. A LOOP has no
roll in it.The ailerons are only used to keep the wings 90 degrees to
the plane of the loop. A IMMELMAN or CUBAN EIGHT has a roll
associated with part of a loop.

The description of making a corkscrew inside a tube is another way of
defining the flight of the airplane when it does a BARREL ROLL.

In my prior post I said to pull one 'G' when I should have said two
'G'. Same 'G' as pulled in a one 'G' turn (one gravity 'G' and one
acceleration 'G').

Not sure you would or would not call a barrel roll a compition
maneuver. Never flew in compiton. In the airshows we used to put on
didn't do BARREL ROLLS becaue they were not very spectular from the
ground nor percicsion manuevers..

In airshows many times we would do a 8 point SLOW ROLL stoppmg
momentarily every 45 degrees of roll. This is a precison maneuver and
takes a lot of practice with elevator, rudder and aileron in
coordination to do correctly and with precision so looks good from
ground. Seen in compition today.

My reference is years and years of doing acrobatics and teaching same
in both conventional aircraft and jets.

As a matter of interest, most of the victory rolls you see of Fighters
returning from a combat mission with kills are aileron rolls. You
could see some (rare) put a little forward stick in when inverted but
had to look close.

Some birds didn't do good aileron rolls (P-51 for instanace) If you
did an aileron roll on the deck you normally bumped the stick upside
down to keep the nose up. The P-40 however aileron rolled like a spool
on a thread.

Big John


On Sun, 09 Nov 2003 03:55:51 GMT, Robert Moore
> wrote:

>Big John > wrote
>> 1. A 'barrel roll' is a roll where (if done properly) you as a
>> passenger, with your eyes closed, can not tell you did a roll.
>> The ball stays centered and if one 'G' is maintained, it feels
>> like straight and level flight. Starting nose position and of
>> course air speed varies between underpoweed GA aircraft and
>> super sonic Fghters.
>
>Hey John, I didn't make-up that post, it came straight from:
>
>http://acro.harvard.edu
>
>The Barrel Roll is a not competition maneuver. The barrel roll is a
>combination between
>a loop and a roll. You complete one loop while completing one roll at
>the same time.
>The flight path during a barrel roll has the shape of a horizontal
>cork screw. Imagine a big
>barrel, with the airplanes wheels rolling along the inside of the
>barrel in a cork screw path.
>During a barrel roll, the pilot experiences always positive G's. The
>maximum is about 2.5 to
>3 G, the minimum about 0.5 G.
>
>Care to give us a reference for your definition?
>
>Bob

[Robert Moore]

Big John > wrote

> You talk about doing a LOOP in association with a roll.

No John, I didn't talk or write about...... I just quoted from the
acro.harvard.edu web site and William Kershner's fine book.
You may not have seen the picture from the Kershner book when you
wrote this, but write back when you have seen the barrel roll as
described by someone who is considered an authority in the field.

> My reference is years and years of doing acrobatics and teaching
> same in both conventional aircraft and jets.

Still waiting for reference documentation. :-)

Bob

[Robert Moore]

Big John > wrote

> My reference is years and years of doing acrobatics and teaching
> same in both conventional aircraft and jets.

Check-out Mr. William Kershner at:

http://www.kershnerflightmanuals.com/

Bob

[Big John]

Robert

Talk me through a loop doing a Barrel Roll. We must be using different
words or maneuvers?

First let me try a different set of words for a GA barrel roll.

1. Drop the nose and pick up 20-25 mph.
2. Start a nose low left turn in the shallow dive and turn 20-30
degrees.
3, Start pulling nose up and reversing turn using 1 'G' of
acceleration (plus 1 G of gravity).
4. Continue the constant rate of roll and the 2 'G's on aircraft.
5. After passing the inverted position continue roll pulling the 2 G's
until bird is back with wings level.
6. Ending nose may be level or down depending on aircraft, starting
airspeed and rate of roll.

You can make a tight barrel roll pulling more that the 2 G's if you
want and using more aileron. If tighter will go around faster of
course.

Now your turn with the help of the guy who wrote the book you read.

Don't know what base you got your Pilot training at and the years. I
was at Willie from '49 to '53 and taught Basic. Advanced and Gunnery.

The Pilots always used the acronym "Bird". Lots of the paper forms
that we filled out used the word 'aircraft' however.

On a 172,. I'd do a barrel roll in the bird but not a slow roll or
aileron roll .Either would over stress the bird 99 times out of a
hundred.

Enough. Let the others have the stage now.

Big John


On Sun, 09 Nov 2003 14:54:09 GMT, Robert Moore
> wrote:

>Big John > wrote
>> 1. A 'barrel roll' is a roll where (if done properly) you as a
>> passenger, with your eyes closed, can not tell you did a roll.
>> The ball stays centered and if one 'G' is maintained, it feels
>> like straight and level flight. Starting nose position and of
>> course air speed varies between underpoweed GA aircraft and
>> super sonic Fghters.
>> There are also a few fine points the experts use that I have not
>> covered but above are the basics.
>>
>> Been there done that for longer (65 years) than BOb has been
>> flying. :o)
>
>I have e-mailed BigJohn and posted at:
>
> alt.binaries.pictures.aviation
>
>a scan from William Kershner's book, The Flight Instructor's
>Manual, in which he describes the barrel roll as an acrobatic
>maneuver. You probably know that Mr. Kershner is one of the most
>respected names in the flight training field, having authored
>several books on the subject. Not as funny as Machado, but he has
>been around for a much longer period of time.
>I haven't scanned and OCRed the text because I think that the
>picture is self-explanitory, but if it would help, I will do the
>page of text describing the barrel roll.
>
>Note that as mentioned in my previous post quoting from:
>
>http://acro.harvard.edu
>
>that one cannot maintain "one G" in a barrel roll since it involves
>both a loop and a roll. In order to perform the loop portion, one
>must pull at least 3-3.5 Gs in the pull-up and a similiar force in
>the pull-out. While inverted, the g-force drops to .5-1 g as in a
>normal loop.
>
>I readily conceed that Big John as been around a bit longer than I,
>but by the the time that I flew in the military, we were learning
>to fly in "airplanes", not "birds". :-) :-)
>
>Bob
>

[Dale]

In article >,
Robert Moore > wrote:


> No John, I didn't talk or write about...... I just quoted from the
> acro.harvard.edu web site and William Kershner's fine book.
> You may not have seen the picture from the Kershner book when you
> wrote this, but write back when you have seen the barrel roll as
> described by someone who is considered an authority in the field.

I've been shown two different ways to do a barrel roll.

The first was to pick a reference off one wingtip. Start pulling and
rolling toward the reference point. Once inverted you would be 90
degrees off original heading (pointed at the ref point). You continue
to roll and pull returning to the original heading.

The second way was to pick a reference point over the nose. Put the
nose slightly to one side of that point then roll and pull keeping the
nose the same distance from the reference point.

The first is the big loopy typy barrel roll - and a lot of fun to do.

The second is a much tighter roll without any loop.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

[vincent p. norris]

> Does the water spill because the aileron roll is *not*
>a positive-G maneuver, or because the forces on it are not balanced
>laterally or longitudinally? (I can't do the experiement because there's
>nowhere to put the glass in the plane I fly).

If you can tie or tape a string with a small weight on the end to the
top of your canopy or windshield, you could use that.

Let's take a snapshot of the airplane at the moment it is inverted.

At that instant, (as at all other times), gravity is exerting a force
of 1 G on the airplane, down toward the earth--in other words "upward"
in relation to the airplane. What we normally call one negative G.

Now, as Einstein pointed out, "acceleration" is a force
indistinguishable from gravity. In this context, acceleration does
not mean "increasing speed," it means "changing direction." (As the
acceleration of a steep turn exerts Gs on the airplane.)

To counteract the one negative G now being exerted on the airplane by
gravity, plus a little more to make it a positive G maneuver, we must
have acceleration, of the sort experienced when pulling out of a dive
or in a loop--although not that much. That is, the nose of the
airplane must "rise"--in relation to the airplane-- to provide more
than 1G of positive acceleration.

If the stick is over to one side, but not pulled back, how is that
acceleration provided? I do not see the nose of the airplane "rise"
while I'm inverted in an aileron roll.
>
>Or do it in a Cessna Aerobat -- which requires a positive G force to
>keep the oil and fuel running. I can get the engine to stutter in a
>second or two in a slow roll (more like a slowish roll in an Aerobat,

I've never flown an Aerobat, but if it aileron rolls as fast as an
SNJ, then the engine won't stutter simply because the maneuver doesn't
last long enough. No SNJ I've flown stutters even in a properly done
slow roll--in which the stick is moved *forward* to keep the nose up
(in relation to the horizon) while inverted.

vince norris

[vincent p. norris]

>>> Place a glass of water atop the instrument
>> > panel and execute a steep turn. It won't stay there,
>>
>> It should!!! If not, you're not using the controls properly.
>> I teach my students to execute co-ordinated steep turns,
>> doesn't everyone do it that way???
>
>The point is that it will likely move, not because there is a negative G
>situation, but because it takes very little lateral G force to knock it off.

Seems to me it would take MORE lateral force to knock it off than
when the airplane is at rest on the ground, because in a coordinated
tight turn, or a loop, additional Gs are causing the glass to press
down harder on the surface.

vince norris

[vincent p. norris]

>1. A 'barrel roll' is a roll where (if done properly) you as a
>passenger, with your eyes closed, can not tell you did a roll. The
>ball stays centered and if one 'G' is maintained,

I suspect there is more than one definition of a "barrel roll."

The ex-Air Force P-47 pilot I've flown with does a peculiar corkscrew
barrel roll that bears virtually no resemblance to the one I was
taught at Pensacola.

The barrel roll I was taught, and like to do, cannot be done at a
constant 1 G.

There is positive acceleration all the way around (see my post just
above), that is, the stick is back, and the nose keeps coming "up,"
all the way around.

(The ball is in the center all the way around, too, and a glass of
water will not spill.)

That positive acceleration means that more than 1 G is experienced
during those parts of the roll in which the airplane is essentially
upright.

vince norris

[Robert Moore]

Big John > wrote

> Talk me through a loop doing a Barrel Roll. We must be using
> different words or maneuvers?

John, have you looked at the barrel roll picture that I e-mailed
you and posted on alt.binaries.pictures.aviation?
If not, further discussion will be of no use.

Have you checked the "Willian Kershner" web site and read the
author's credentials?
If not, you just leave us wondering "who-the-hell" is Big John,
and what credence should we give to his unsupported assertions?
Mr. Kershner owns and operates an Aerobatic Flight School and
has authored the book, "The Basic Aerobatic Manual" which as he
points out, was an offshoot (with permission) of the manual he
helped write for Cessna Aircraft in 1969.

> First let me try a different set of words for a GA barrel roll.

Here are William Kershner's words that accompanied the diagram of
the barrel roll in his The Flight Instructor's Manual in which he
devotes all of chapter 5 (66 pages) to aerobatic instruction.

Quote..............or should I say OCR'ed

THE BARREL ROLL
• Preparation. It's almost impossible to draw a barrel roll
on the chalkboard, but a model will give the desired results.
Have the trainee study the references.

•Explanation. The barrel roll is a precise maneuver in which
the airplane is rolled around an imaginary point 45° to
the original flight path. A positive-g level is maintained
throughout the maneuver, and the ball in the turn indicator
should stay in the middle.

You may wonder why the barrel roll is taught this late,
since it appears to be so simple. Well, it is a precise maneuver
requiring particular airplane attitudes at particular reference
points, which is difficult for the average trainee to do properly
at first.

This maneuver might be considered an exaggeration of the
wingover, but instead of starting to shallow the bank at the 90°
position, the pilot must steepen it continually until the airplane
has rolled 360° and is back on the original heading. The rate of
roll must be much greater than that used for the wingover
because the airplane must be in a vertical bank at 45° of turn,
and it must be inverted at 90° of turn. The roll and turn is
continued until the airplane is headed in the original direction with
the wings level. Compare the barrel roll in Fig. 23-12 with the same
view of the wingover in Fig. 20-7.

From behind the maneuver looks as though the airplane is being
flown around the outside of a barrel. This is a very good maneuver
for gaining confidence and keeping oriented while flying inverted in
balanced flight.
Good coordination is required to do the barrel roll properly and
the trainee will show an improvement in that area after a session of
barrel rolls.

The barrel roll is generally more difficult and precise than the
aileron roll, and he may have to work on this one awhile.

Why-
The barrel roll is one of the best maneuvers for improving
orientation.

Unlike the other acrobatic maneuvers covered thus far, the barrel
roll requires a constantly changing bank and pitch (with attendant
changing airspeed) and a radical change in heading (90°) while the
airplane is rolling. The average trainee probably will be looking at
the wing tip at a time when he should be checking the nose, or vice
versa.
When he is able to stay well oriented in the barrel roll, he is ready
to move on to the reverse Cuban eight or reverse cloverleaf.

How-
You might use the following explanation, or develop your own:
(1) Make sure the area is clear, then pick a reference on the
horizon off the wing tip as in the wingover and lazy eight.
(2) Set the throttle to low cruise rpm and ease the nose over to
pick-up about 10 K more than used for the wingover or set up
the airspeed used for a loop, whichever is higher. Power
adjustment should not be necessary during the maneuver. You
might have some of your sharper trainees apply full power as
the airplane approaches inverted and then remind them to
throttle back as the airspeed picks up in the last part of the
maneuver.
(3) Smoothly pull the nose up and start a coordinated climbing turn
(note that it will have to be at a much faster rate than was
used for the wingover) toward the reference point. (Assume that
at first the roll will be to the left.)
(4) When the nose is 45° from the original heading, it should be
at its highest pitch attitude and the left bank should be
vertical.
(5) When the nose is at 90° from the original heading, you should
be looking directly at the reference point that was originally
off the wing tipfrom a completely inverted position
(momentarily).
(6) When the airplane heading is again 45° from the original, the
bank is vertical but you will be in a right bank as far as the
ground is concerned; that is, the right wing is pointing
straight down at this instant of roll. The nose will be at its
lowest pitch attitude at this point.
(7) The roll is continued to wings-level flight as the nose is
raised back to the cruise attitude.

The maneuver must be symmetrical; the nose must go as far above the
horizon as below. The barrel roll requires definite checkpoints to
ensure that the airplane is at the correct attitude throughout. It is
interesting to note that if the barrel roll is to the left, all of
the airplane's path is to the left of the original line of flight and
the airplane's nose is always pointed to the left of the original
flight line (until it merges again at the completion of the
maneuver). The opposite occurs, naturally, for the barrel roll to the
right.

Another method of doing a barrel roll is to pick a reference on the
horizon, turn the airplane 45° to the reference point, and proceed to
make a wide roll around this real point. One disadvantage of this
method for the newcomer is that it depends on the pilot's own
judgment of how large the orbit around the point should be. For an
introduction to the maneuver, the first method is usually better, but
you may prefer the second and work out your own techniques of
instructing it.

Demonstration.
Try not to lose the reference point yourself while demonstrating
this one. You may find your explanation is not keeping up with the
airplane, which usually results in sputtering and stuttering while
the maneuver proceeds to its foregone conclusion -and then you have
to do a new demonstration. Don't worry, this will happen plenty of
times during your career of instructing aerobatics -when your mouth
can't keep up with your brain or the maneuver-and it can ease tension
if you react to it with humor.

Usually the trainee is surprised to see the same wing tip back on the
reference point and may confess that, like the first snap roll, the
earth and sky were blurred and he had no idea where the reference was
during the maneuver.

Practice.
You may rest assured the trainee will "lose" the reference point
during the first couple of barrel rolls. He'll usually stare over the
nose, seeingnothing but blue sky or ground and not really seeing the
point at all.

Common errors during barrel rolls include these:
1. Not pulling the nose high enough in the first 45° of the
maneuver, which means that the highest and lowest nose positions
are not symmetrical to the horizon.
2. Not maintaining a constant rate of roll. Usually things are fine
at the 45° position; the nose is at its highest pitch and the
bank is vertical.
As you approach the position of 90° of turn you will probably
find that he is not going to be completely inverted at that
point and will have to rush things a bit to make it. The usual
reason is that he did not maintain a constant rate of roll.
Remember that the nose is up and the airspeed is slower in this
segment of the maneuver, so the controls must be deflected more
to get the same rate. This is where coordination comes in. Watch
for it in particular.
3. Letting the nose drop after passing the 90° point; losing too
much altitude and gaining excess airspeed.
4. Failure to roll out on the original heading; having the wing tip
well ahead, or well behind, the reference when the maneuver is
completed.

Evaluation and Review.
Review each barrel roll briefly in the air, and have the trainee
use the model on the ground. This one can be hard to "see," so go
over it again as necessary after getting on the ground.

By the time a half-dozen barrel rolls have been practiced, the
average trainee should be oriented throughout the maneuver even
though he may still have minor problems of heading and symmetry.
After a dozen rolls he should be starting to work on a constant roll
rate and starting to ease his heading problems. After several
hundred, he may begin to be satisfied with his barrel rolls but will
realize that constant practice is required.

Unquote.................

But John...you really should look at that picture.

Bob

[Robert Moore]

Dale > wrote

> The second way was to pick a reference point over the nose. Put
> the nose slightly to one side of that point then roll and pull
> keeping the nose the same distance from the reference point.

This is what Kershner has to say about the second method.

"Another method of doing a barrel roll is to pick a reference on the
horizon, turn the airplane 45° to the reference point, and proceed to
make a wide roll around this real point. One disadvantage of this
method for the newcomer is that it depends on the pilot's own
judgment of how large the orbit around the point should be. For an
introduction to the maneuver, the first method is usually better, but
you may prefer the second and work out your own techniques of
instructing it."

It should be noted that by using the 45 degree angle to the reference
point, one gets the same maneuver if done properly.

Bob Moore

[Hamish Reid]

In article >,
vincent p. norris > wrote:

> > Does the water spill because the aileron roll is *not*
> >a positive-G maneuver, or because the forces on it are not balanced
> >laterally or longitudinally? (I can't do the experiement because there's
> >nowhere to put the glass in the plane I fly).
>
> If you can tie or tape a string with a small weight on the end to the
> top of your canopy or windshield, you could use that.

Indeed. And when you do that, you observe positive G's all the way
around an aileron roll (in the aircraft I fly, at least). I do a bit of
aerobatics photography, and I'm absolutely required to be able to
anticipate G forces to keep the camera from smashing into something else
(or myself).

> Let's take a snapshot of the airplane at the moment it is inverted.
>
> At that instant, (as at all other times), gravity is exerting a force
> of 1 G on the airplane, down toward the earth--in other words "upward"
> in relation to the airplane. What we normally call one negative G.
>
> Now, as Einstein pointed out, "acceleration" is a force
> indistinguishable from gravity. In this context, acceleration does
> not mean "increasing speed," it means "changing direction." (As the
> acceleration of a steep turn exerts Gs on the airplane.)

Indeed. And an aircraft in an aileron roll changes direction constantly
as it describes a ballistic corkscrew-like path (S&G).

> To counteract the one negative G now being exerted on the airplane by
> gravity, plus a little more to make it a positive G maneuver, we must
> have acceleration, of the sort experienced when pulling out of a dive
> or in a loop--although not that much.

Indeed.

> That is, the nose of the
> airplane must "rise"--in relation to the airplane-- to provide more
> than 1G of positive acceleration.

Or the corkscrew motion of an aileron roll must provide enough "outward"
(normal) force to counteract the downward force of gravity. Which it
does.... We're not doing a slow roll here, so the longitudinal axis of
the aircraft describes a circle around the axis of the maneuver itself.
The maneuver starts with a pullup, and that pullup is never really lost.

> If the stick is over to one side, but not pulled back, how is that
> acceleration provided? I do not see the nose of the airplane "rise"
> while I'm inverted in an aileron roll.

At the start of most aileron rolls the stick *is* pulled back -- to get
you to the magic 30 degree point with a small 2G pullup. Then by the top
of the roll the nose is trending down, with enough normal force from the
corkscrew motion to keep the G's positive. Once again, as described by
Szurovy & Goulian (quoted in the bits you snipped) and nearly every text
or reference I can find, and my own experience, a simple aileron roll is
one of the canonical positive G maneuvers (unlike the slow roll, which
can result in negative G's in many aircraft).

> >Or do it in a Cessna Aerobat -- which requires a positive G force to
> >keep the oil and fuel running. I can get the engine to stutter in a
> >second or two in a slow roll (more like a slowish roll in an Aerobat,
>
> I've never flown an Aerobat, but if it aileron rolls as fast as an
> SNJ, then the engine won't stutter simply because the maneuver doesn't
> last long enough.

*Nothing* in an Aerobat is fast :-). But in fact, since the aileron roll
(as described by S & G, again...) is a positive G maneuver, you can do
it without worrying about the fuel feed (or the oil). You can certainly
screw up an aileron roll and get non-postive G's (as I've discovered
:-)), but it takes extra effort (or forgetting to keep the ailerons
fully deflected...).

>No SNJ I've flown stutters even in a properly done
> slow roll--in which the stick is moved *forward* to keep the nose up
> (in relation to the horizon) while inverted.

Which, if done as slowly as I do them, will result in non-positive
G's... it takes only a second or two to make the Aerobat stutter.

Hamish

[Scott Lowrey]

Scott Lowrey wrote:
> If I'm crusing along at 100 KIAS in a 172 in clear air and I roll left
> while maintaining neutral rudder, what will happen if I don't
> neutralize the ailerons?
>

WOW. I was away for several days and I think I'd see two replies to my
post before I left.

Thanks for all the replies - you guys are easy to get going but never
boring... well, usually never. :+)

Anyway, I thought about Vne being a problem later. Seems like the right
thing to do (after drinking my cup of water, tying a string to the
panel, plugging the fuel vents, and hoping I have enough oil) would be
to nose up a bit prior to the roll and push forward while inverted.

I know this isn't the plane for this kind of maneuver and I have no
intention of trying it. Sure would like to do some acro someday,
though. Maybe when I save enough to by that Stearman I've always wanted.

-Scott

[Big John]

Bob

Read Kershner's life story. Note that he left Moffett and crapped out
of the Navy the year I arrived at Moffett to fly All Weather Jet
Fighters (VF-23).

The Navy was just transitioning from Prop Fighters (F4U like he flew
in West Pac, etc) and one of my tasks was to give them the experience
of Air Force Jet Fighter operations including energy management which
was very important in those first generation jet fighters..

Reading his description of life events it seems he pushes the envelope
some like Zzzzom.

I see nothing he has done to warrant your placing so high on a
pedestal. He gives credit to only one document where he lifted some
data/technique. I also detect the wording of other manuals I have seen
through the years that he didn't give credit to.

Of course it may be just how many ways you can say loop?

He says he flies one or two students a month.That's not enough to
maintain proficiency or write from a current background.

You keep asking for my credentials. What do you want, my Military Form
5 where every flight I make in 28+ years is listed. There is at least
one or more pages per month depending on activity and totals well over
350 pages and about 2 1/2 - 3 inches thick weighing 3-4 pounds.

Or my formal education of BS with work on a MS.

Or the Patent number of my patents?

I'm married and have four grown daughters with three grand children
and three great grand children.

I'm over 21 and legal to buy 'booze' so drink Vodka on the rocks.

My GA Flight Logs are pretty thin as I didn't log a lot of the time
because I wasn't trying to build to any number of hours since I had
over 6500 in heavy iron.

It looks like there are several different ideas about acrobatic flyng
on this thread. I've expounded on mine so others can list their way
and I'll set back and might learn somethng??? One is never too old to
learn it is said.

I don't suffer fools but can be moved by facts.

Fly safe and keep the ball in the center unless you are slipping the
excess altitude off on final or landing in a cross wind.


Big John



On Sun, 09 Nov 2003 23:12:40 GMT, Robert Moore
> wrote:

>Big John > wrote
>
>> My reference is years and years of doing acrobatics and teaching
>> same in both conventional aircraft and jets.
>
>Check-out Mr. William Kershner at:
>
>http://www.kershnerflightmanuals.com/
>
>Bob

[Big John]

On Mon, 10 Nov 2003 02:02:01 GMT, Robert Moore
> wrote:

----clip----

But John...you really should look at that picture.

----clip----

OK. I reconfigured my computer and subscribed to
"alt.binaries.pictures.avation" and down loaded the last 50 posts and
don't find anything from you.

I'll go back and download everything from day one to look for your
picture and then blow away the other thousands I down loaded.

Since I know what a barrel roll is and how to do same and have done
then for many many years, why should l look at a picture you drew and
if done as described by your expert I seriously doubt if anyone could
fly ???

I think I'll let you experts have the floor to do with as you choose.

I'm scheduled for a kidney x-ray tomorrow and need to go in refreshed.
(No muzzle loaders tonight - we used to call them booze berries <G>)

Big John

[Peter]

Big John wrote:

> Robert
>
> You talk about doing a LOOP in association with a roll. A LOOP has no
> roll in it.The ailerons are only used to keep the wings 90 degrees to
> the plane of the loop. A IMMELMAN or CUBAN EIGHT has a roll
> associated with part of a loop.
>
> The description of making a corkscrew inside a tube is another way of
> defining the flight of the airplane when it does a BARREL ROLL.

As a lurker here who has never and will never do a single loop or roll, it
seems to me you two are both describing exactly the same maneuver but using
slightly different words.

Both you and Bob agree that the barrel roll consists of having the airplane
follow a corkscrew path as if it were following the inside wall of an
imaginary barrel, or tube, in the sky.
If the plane were to roll while going straight down the long axis of the
tube it would be an ordinary "slow" roll. OTOH, if the plane were flying
along the inside circumference (i.e. at 90 degrees to the long axis) of the
tube it would be doing loops. The corkscrew path of a barrel roll is
halfway between these two situations (i.e. at about a 45 degree angle to
the long axis of the tube), so it doesn't seem unreasonable to describe it
as the combination of a loop and a roll.

[Big John]

Bob

Found and subscribed to <alt.binaries.pictures.avation> and down
loaded all the postings in that Group. About 500 or so. Sat down and
went through them untiL I found your posting. Drilled down and finally
got the picture you are so hot about.

My comments, No one could do a barrel roll as depicted in your
picture. You show a single plane (not airplane) picture and maneuver
is done along an extended length of airspace.

You don't enter at 90 degrees to the desired direction of flight. Your
picture looks more like a single leaf of a four leaf clover.

Maybe this is what you call a barrel roll today but sure isn't the
classic maneuver.

On your query on my credentials in this post. I have answered that in
another posting. However to follow along that line since you won't let
it go, who are you to question my credentials? You sound like some
'want a be' that's never spent time on his back maybe not even a
pilot?. I may well have more inverted time than your total time????.

I can do a double emmelman in a F-80/T-33 and a slow roll in aT-6/SNJ
without the engine cutting out when inverted. Also I can do a loop in
a T-6/SNJ starting from zero indicated airspeed. Want to try any of
those maneuvers? Lets see your buddy Kershner do those.He's got T-33
time so ask him if he ever did a double emmelman in it and if so how
he did it (airspeed, altitude, G's, etc)? I've got thousands of hours
of tail wheel time and never ground looped or let one of my students
ground loop on any kind of a field and in any type of weather/wind.

BOb and I may well have the highest tail wheel time of any on this
group and he's got a lot???

Among others I have instructed both Chinese and Norwegian Air Force
students and was awarded wings from both countries, which I am
authorized by our government to wear (you need permission you know).

I am a member of the caterpillar club :o(

When do you want me to quit??????

The more we talk the more I disagree with you so need to shut things
down before we get violent <G>

If you want, take the last shot (some people just have to) and that's
it.

And the best to thee from the wee ones.

Big John


On Mon, 10 Nov 2003 02:02:01 GMT, Robert Moore
> wrote:

>Big John > wrote
>
>> Talk me through a loop doing a Barrel Roll. We must be using
>> different words or maneuvers?
>
>John, have you looked at the barrel roll picture that I e-mailed
>you and posted on alt.binaries.pictures.aviation?
>If not, further discussion will be of no use.
>
>Have you checked the "Willian Kershner" web site and read the
>author's credentials?
>If not, you just leave us wondering "who-the-hell" is Big John,
>and what credence should we give to his unsupported assertions?
>Mr. Kershner owns and operates an Aerobatic Flight School and
>has authored the book, "The Basic Aerobatic Manual" which as he
>points out, was an offshoot (with permission) of the manual he
>helped write for Cessna Aircraft in 1969.
>
>> First let me try a different set of words for a GA barrel roll.
>
>Here are William Kershner's words that accompanied the diagram of
>the barrel roll in his The Flight Instructor's Manual in which he
>devotes all of chapter 5 (66 pages) to aerobatic instruction.
>
>Quote..............or should I say OCR'ed
>
>THE BARREL ROLL
>• Preparation. It's almost impossible to draw a barrel roll
> on the chalkboard, but a model will give the desired results.
> Have the trainee study the references.
>
>•Explanation. The barrel roll is a precise maneuver in which
> the airplane is rolled around an imaginary point 45° to
> the original flight path. A positive-g level is maintained
> throughout the maneuver, and the ball in the turn indicator
> should stay in the middle.
>
> You may wonder why the barrel roll is taught this late,
>since it appears to be so simple. Well, it is a precise maneuver
>requiring particular airplane attitudes at particular reference
>points, which is difficult for the average trainee to do properly
>at first.
>
> This maneuver might be considered an exaggeration of the
>wingover, but instead of starting to shallow the bank at the 90°
>position, the pilot must steepen it continually until the airplane
>has rolled 360° and is back on the original heading. The rate of
>roll must be much greater than that used for the wingover
>because the airplane must be in a vertical bank at 45° of turn,
>and it must be inverted at 90° of turn. The roll and turn is
>continued until the airplane is headed in the original direction with
>the wings level. Compare the barrel roll in Fig. 23-12 with the same
>view of the wingover in Fig. 20-7.
>
> From behind the maneuver looks as though the airplane is being
>flown around the outside of a barrel. This is a very good maneuver
>for gaining confidence and keeping oriented while flying inverted in
>balanced flight.
> Good coordination is required to do the barrel roll properly and
>the trainee will show an improvement in that area after a session of
>barrel rolls.
>
> The barrel roll is generally more difficult and precise than the
>aileron roll, and he may have to work on this one awhile.
>
>Why-
>The barrel roll is one of the best maneuvers for improving
>orientation.
>
> Unlike the other acrobatic maneuvers covered thus far, the barrel
>roll requires a constantly changing bank and pitch (with attendant
>changing airspeed) and a radical change in heading (90°) while the
>airplane is rolling. The average trainee probably will be looking at
>the wing tip at a time when he should be checking the nose, or vice
>versa.
>When he is able to stay well oriented in the barrel roll, he is ready
>to move on to the reverse Cuban eight or reverse cloverleaf.
>
>How-
>You might use the following explanation, or develop your own:
>(1) Make sure the area is clear, then pick a reference on the
> horizon off the wing tip as in the wingover and lazy eight.
>(2) Set the throttle to low cruise rpm and ease the nose over to
> pick-up about 10 K more than used for the wingover or set up
> the airspeed used for a loop, whichever is higher. Power
> adjustment should not be necessary during the maneuver. You
> might have some of your sharper trainees apply full power as
> the airplane approaches inverted and then remind them to
> throttle back as the airspeed picks up in the last part of the
> maneuver.
>(3) Smoothly pull the nose up and start a coordinated climbing turn
> (note that it will have to be at a much faster rate than was
> used for the wingover) toward the reference point. (Assume that
> at first the roll will be to the left.)
>(4) When the nose is 45° from the original heading, it should be
> at its highest pitch attitude and the left bank should be
> vertical.
>(5) When the nose is at 90° from the original heading, you should
> be looking directly at the reference point that was originally
> off the wing tipfrom a completely inverted position
> (momentarily).
>(6) When the airplane heading is again 45° from the original, the
> bank is vertical but you will be in a right bank as far as the
> ground is concerned; that is, the right wing is pointing
> straight down at this instant of roll. The nose will be at its
> lowest pitch attitude at this point.
>(7) The roll is continued to wings-level flight as the nose is
> raised back to the cruise attitude.
>
>The maneuver must be symmetrical; the nose must go as far above the
>horizon as below. The barrel roll requires definite checkpoints to
>ensure that the airplane is at the correct attitude throughout. It is
>interesting to note that if the barrel roll is to the left, all of
>the airplane's path is to the left of the original line of flight and
>the airplane's nose is always pointed to the left of the original
>flight line (until it merges again at the completion of the
>maneuver). The opposite occurs, naturally, for the barrel roll to the
>right.
>
>Another method of doing a barrel roll is to pick a reference on the
>horizon, turn the airplane 45° to the reference point, and proceed to
>make a wide roll around this real point. One disadvantage of this
>method for the newcomer is that it depends on the pilot's own
>judgment of how large the orbit around the point should be. For an
>introduction to the maneuver, the first method is usually better, but
>you may prefer the second and work out your own techniques of
>instructing it.
>
>Demonstration.
> Try not to lose the reference point yourself while demonstrating
>this one. You may find your explanation is not keeping up with the
>airplane, which usually results in sputtering and stuttering while
>the maneuver proceeds to its foregone conclusion -and then you have
>to do a new demonstration. Don't worry, this will happen plenty of
>times during your career of instructing aerobatics -when your mouth
>can't keep up with your brain or the maneuver-and it can ease tension
>if you react to it with humor.
>
>Usually the trainee is surprised to see the same wing tip back on the
>reference point and may confess that, like the first snap roll, the
>earth and sky were blurred and he had no idea where the reference was
>during the maneuver.
>
>Practice.
>You may rest assured the trainee will "lose" the reference point
>during the first couple of barrel rolls. He'll usually stare over the
>nose, seeingnothing but blue sky or ground and not really seeing the
>point at all.
>
>Common errors during barrel rolls include these:
>1. Not pulling the nose high enough in the first 45° of the
> maneuver, which means that the highest and lowest nose positions
> are not symmetrical to the horizon.
>2. Not maintaining a constant rate of roll. Usually things are fine
> at the 45° position; the nose is at its highest pitch and the
> bank is vertical.
> As you approach the position of 90° of turn you will probably
> find that he is not going to be completely inverted at that
> point and will have to rush things a bit to make it. The usual
> reason is that he did not maintain a constant rate of roll.
> Remember that the nose is up and the airspeed is slower in this
> segment of the maneuver, so the controls must be deflected more
> to get the same rate. This is where coordination comes in. Watch
> for it in particular.
>3. Letting the nose drop after passing the 90° point; losing too
> much altitude and gaining excess airspeed.
>4. Failure to roll out on the original heading; having the wing tip
> well ahead, or well behind, the reference when the maneuver is
> completed.
>
>Evaluation and Review.
> Review each barrel roll briefly in the air, and have the trainee
>use the model on the ground. This one can be hard to "see," so go
>over it again as necessary after getting on the ground.
>
> By the time a half-dozen barrel rolls have been practiced, the
>average trainee should be oriented throughout the maneuver even
>though he may still have minor problems of heading and symmetry.
>After a dozen rolls he should be starting to work on a constant roll
>rate and starting to ease his heading problems. After several
>hundred, he may begin to be satisfied with his barrel rolls but will
>realize that constant practice is required.
>
>Unquote.................
>
>But John...you really should look at that picture.
>
>Bob
>
>
>
>

[Big John]

Dylan

From my good book (Owners Manual Model 172 and Skyhawk)

Normal category

Gross weight --- 2300#

Flaps up

+3.8 G
-1.52 G

Normal category is non acrobatic

You can do stalls (not whip stalls) and are limited to a max angle of
bank of 60 degrees.

Utility Category

Max gross weight --- 2000#

Flaps up

+4.4 G
-1.76 G

No aerobatic maneuvers are approved except those listed.

Chandelles
Lazy Eights
Steep Turns
Spins
Stall (Except Whip Stalls)

From these figures you can see that it would be touch and go if you
rolled the bird inverted. Of course the figures given are not ultimate
so might only bend things a little :o)

Big John

* Added note. "In the execution of all maneuvers, avoid abrupt use of
controls."



On Mon, 10 Nov 2003 08:13:29 -0000, Dylan Smith
> wrote:

>In article >, Big John wrote:
>> On a 172,. I'd do a barrel roll in the bird but not a slow roll or
>> aileron roll .Either would over stress the bird 99 times out of a
>> hundred.
>
>Really?
>
>All the eileron rolls I've ever done have been distinctly low-G
>manoevres. Dive a little to gain entry speed, pull the nose up to
>about 30 degrees above the horizon, then full aileron until the world
>comes the right way up again, at which point you'll be about 20 degrees
>nose down. The G-meter has never shown more than 1.5G after
>an aileron roll for me, and that was done in the initial pull-up.
>
>I thought a C172 in the utility category was good for 4.2G, not 1.5G!

[Dylan Smith]

In article >, Big John wrote:
> On a 172,. I'd do a barrel roll in the bird but not a slow roll or
> aileron roll .Either would over stress the bird 99 times out of a
> hundred.

Really?

All the eileron rolls I've ever done have been distinctly low-G
manoevres. Dive a little to gain entry speed, pull the nose up to
about 30 degrees above the horizon, then full aileron until the world
comes the right way up again, at which point you'll be about 20 degrees
nose down. The G-meter has never shown more than 1.5G after
an aileron roll for me, and that was done in the initial pull-up.

I thought a C172 in the utility category was good for 4.2G, not 1.5G!

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

[Robert Moore]

Big John > wrote

> My comments, No one could do a barrel roll as depicted in your
> picture. You show a single plane (not airplane) picture and
> maneuver is done along an extended length of airspace.

Not "my" picture. Was scanned from Mr. Kershner's book.

> Maybe this is what you call a barrel roll today but sure isn't
> the classic maneuver.

Same maneuver that I was taught in the T-28 back in 1958.
Check-out this web site:

http://web.winco.net/~efildes/slowroll/barlroll.html

> On your query on my credentials in this post. I have answered
> that in another posting. However to follow along that line since
> you won't let it go, who are you to question my credentials? You
> sound like some 'want a be' that's never spent time on his back
> maybe not even a pilot?. I may well have more inverted time than
> your total time????.

20,000+ hours inverted??? Wow! That's a lot John.
My last aerobatic instructing was done as recently as 1998 in the
YAK-52. Great little airplane....good for +7g's. It combined the
performance of the Navy T-28B (1425 hp) in a T-34 size airframe.
BTW, in addition to a few thousand hours instructing in Boeing
jetliners, I have been an FAA certificated flight instructor since
1970. Spent the years 1993-99 teaching in C-172s.

> BOb and I may well have the highest tail wheel time of any on
> this group and he's got a lot???

Well, I built my own tailwheel airplane and flew it for 10 years.
It was exhibited at the Sun-n-Fun airshow in 1991 and 1992.
According to the factory that provided the kit,(TEAM) I was the first
and probably only person to spin the MiniMax.

Now....in summary, the following three web sites (documentation)
assert that the barrel roll is a combination of a loop and a roll.
But....Big John (no documentation) insists that there is no loop in
a barrel roll.

http://web.winco.net/~efildes/slowroll/barlroll.html
http://acro.harvard.edu
http://www.kershnerflightmanuals.com/

Bob Moore
ATP B-727 B-707 B-720 L-188
CFI A/I AGI IGI
USN S-2F P-2V P-3B

[Maule Driver]

I get it and am smarter for it. Thanks.

My acro terminology is so rooted in RC flying from 30+ years ago, that I've
never realized how differently the terms are used in 'real' a/c.

In RC, the term aileron roll is commonly used for what is called a slow roll
here. It is a straight line roll and can happen very fast. Aileron and
elevator will produce a quite passable axial roll in a hot RC plane. Very
akin to what a full scale jet fighter might do. Pros like my brother will
use top rudder too.

A barrel roll in RC is typically done with rudder in a model without
ailerons. It looks like a full scale aileron roll. Less-than-hot
rudder/elevator only RC plance can do a passable barrel roll because of a
lot of dihedral. You don't even need the elevator if it is setup right.

And in a full scale glider, it's kind of hard to get all the way around a
pure aileron roll as described. You need to be pretty agressive with pitch
and rudder to do a passable 'aileron' roll. At least in my limited
experience.

"Robert Moore" > wrote in message
...
> "Maule Driver" > wrote
> > I have some glider acro training and lot's of RC model acro. I
> > think of axial rolls and barrel rolls. Both benefit from
> > aileron, elevator and rudder input. I've thought that aileron
> > roles are synonymous with axial and slow rolls synonymous with
> > barrel rolls.
>
> From the following web site about aerobatics:
>
> http://acro.harvard.edu/IAC/faq_aerobatics.html
>
> Aileron Rolls
> Aileron rolls are flown with the rudder and elevator in the neutral
> position during the roll. The aileron is fully deflected in the
> direction of the roll. This is the easiest of the rolls to fly.
> The aileron roll is started by pulling the nose up to 20 - 30 degrees
> above the horizon. The elevator is then neutralized and the aileron
> fully deflected in the direction of the roll. The controls are
> maintained in that position till the roll is completed. After the
> roll is completed the nose is usually 20 - 30 degrees below the
> horizon.
>
> The aileron roll is not a competition maneuver.
>
>
> Slow Rolls
> Slow rolls have to be flown normally on a straight line (exception is
> the avalanche). The roll rate has to be constant and the longitudinal
> axis of the plane has to go straight. This requires constantly
> changing rudder and elevator control inputs throughout the roll.
> Hesitation or point rolls include stops at certain roll angles. The
> number on the base of the roll symbol describes the number of points
> the roll would have if it were a 360 degree roll. Allowed are 2
> point, 4 point and 8 point rolls. The fraction on the arrow of the
> roll symbol describes what fraction of a full roll is to be executed.
> If no points are specified, rolling is done without hesitations. If
> no fraction is specified, a roll symbol that starts at the line
> specifies a half roll (see description of the Immelman). A roll
> symbol that crosses the line specifies a full roll (first figure).
> The second figure shows the symbol for 2 points of a 4 point roll
> (adding up to half a roll) from upright to inverted flight.
>
> Snap Rolls
> Snap or flick rolls also have to be flown normally on a straight
> line. A snap roll is similar to a horizontal spin. It is an
> autorotation with one wing stalled. In the regular snap, the plane
> has to be stalled by applying positive g forces. In an outside snap,
> the plane is stalled by applying negative g. In both cases rudder is
> then used to start autorotation just like in a spin.
>
> Barrel Roll
> The Barrel Roll is a not competition maneuver. I The barrel roll is a
> combination between a loop and a roll. You complete one loop while
> completing one roll at the same time. The flight path during a barrel
> roll has the shape of a horizontal cork screw. Imagine a big barrel,
> with the airplanes wheels rolling along the inside of the barrel in a
> cork screw path. During a barrel roll, the pilot experiences always
> positive G's. The maximum is about 2.5 to 3 G, the minimum about 0.5
> G.
>
> Bob Moore

[vincent p. norris]

>Or the corkscrew motion of an aileron roll must provide enough "outward"
>(normal) force to counteract the downward force of gravity.

I think I understand what you're saying, Hamish. It may depend on the
airplane. An SNJ doesn't "corkscrew" very much. It would hardly be
enough to provide positive G in excess of 1.0.

>The maneuver starts with a pullup...

It does start with a slight pullup, but then then back-prssure on the
stick is released, to produce what approximates a zero-G situation.
(Don't you do that in an Aerobat?)

I thnk the best description of an aileron roll is to call it a zero-G
maneuver. Not *exactly* zero, to the tenth decimal place, but close to
zero all the way around.

>and that pullup is never really lost

I don't understand that. I need to use some right rudder after
passing the half-way point of a left aileron roll, or I'll end up
with the nose pointing down about 20 degrees.

> (unlike the slow roll, which can result in negative G's in many aircraft).

I don't understand that, either. You're saying there are airplanes
that can perform a slow roll without experiencing negative Gs?

vince norris

[Hamish Reid]

In article >,
vincent p. norris > wrote:

> >Or the corkscrew motion of an aileron roll must provide enough "outward"
> >(normal) force to counteract the downward force of gravity.
>
> I think I understand what you're saying, Hamish. It may depend on the
> airplane. An SNJ doesn't "corkscrew" very much. It would hardly be
> enough to provide positive G in excess of 1.0.

Well, the *whole point* of a textbook aileron roll is to maintain
positive G's -- not 1+ G's, but *positive* -- all the way through the
maneuver, regardless of whether you do it in a Pitts or a puny Aerobat
(the Pitts is a lot more, erm, exciting in this respect :-)).

> >The maneuver starts with a pullup...
>
> It does start with a slight pullup, but then then back-prssure on the
> stick is released, to produce what approximates a zero-G situation.
> (Don't you do that in an Aerobat?)

The textbook aileron roll in an Aerobat starts with a shallow dive to
120 KIAS, then a smart pullup to 30 degrees pitch, then a quick
simultaneous full-over on the ailerons and neutralization of the
elevator until pullout. Apply rudder as appropriate... The Pitts is
pretty much the same, but at least with the constant speed prop you
don't have to spend so much time obsessing about the throttle.

> I thnk the best description of an aileron roll is to call it a zero-G
> maneuver. Not *exactly* zero, to the tenth decimal place, but close to
> zero all the way around.

In no plane I've ever done an aileron roll in is the G force "close to
zero all the way around". In fact, it's close to 2G's at two points in
the maneuver (pullup and pullout), and it's probably around .5 to 1 G
over the top.

> >and that pullup is never really lost
>
> I don't understand that. I need to use some right rudder after
> passing the half-way point of a left aileron roll, or I'll end up
> with the nose pointing down about 20 degrees.

Remember, half way around your altitude is still quite a bit higher than
it was when you started the maneuver....

> > (unlike the slow roll, which can result in negative G's in many aircraft).
>
> I don't understand that, either. You're saying there are airplanes
> that can perform a slow roll without experiencing negative Gs?

No I'm saying that true textbook slow rolls result in negative G's (and
are nearly impossible in an Aerobat, but never mind...).

Hamish

[vincent p. norris]

>> An SNJ doesn't "corkscrew" very much. It would hardly be
>> enough to provide positive G in excess of 1.0.
>
>Well, the *whole point* of a textbook aileron roll is to maintain
>positive G's -- not 1+ G's, but *positive* -- all the way through the
>maneuver....

Sorry, I didn't express myself well. I meant "It would hardly be
enough to provide positive G in excess of 1.0, enough to negate the
negative 1 G caused by gravity, plus a bit more to make it a positive
G maneuver."

BTW, I looked again at a tape of Tex Johnston's rolls, going and
coming. I cannot detect any "corkscrewing."

> regardless of whether you do it in a Pitts or a puny Aerobat
>(the Pitts is a lot more, erm, exciting in this respect :-)).

I'm sure it is. I've had a little time in a friend's Starduster 2
but never had the pleasure of flying a Pitts.
>
>> It does start with a slight pullup, but then then back-prssure on the
>> stick is released, to produce what approximates a zero-G situation.
>> (Don't you do that in an Aerobat?)
>
>The textbook aileron roll in an Aerobat starts with a shallow dive to
>120 KIAS, then a smart pullup to 30 degrees pitch, then a quick
>simultaneous full-over on the ailerons and neutralization of the
>elevator until pullout. Apply rudder as appropriate...

I would agree with that, except I neutralize the elevator THEN begin
the roll.

I don't think of the pullup as part of the maneurver, but as
"preparation" for it.

> In fact, it's close to 2G's at two points in
>the maneuver (pullup and pullout), and it's probably around .5 to 1 G
>over the top.

I don't think of the pullup as part of the maneurver, but as
"preparation" for it. I don't pull up that sharply, and if I have to
"pull out" at the end, I figure I didn't do it right.

If by "over the top" you mean when 180 degrees inverted, I find that
very hard to imagine, based solely on my experience. (I've never
flown an airplane with a G-meter.) I don't hang on the seat belt, as
in a slow roll, but I feel a bit "weightless." I don't seem to be
pushing down (up?) on the seat very hard.
>
>Remember, half way around your altitude is still quite a bit higher than
>it was when you started the maneuver....

Yes, I think the airplane follows something like a "ballistic curve"
during the maeuver. Certainly, it gets dang little vertical lift as
it rolls past the 90 degree and 270 degree points.

Despite the fact that the nose is pointed up slightly, the airplane is
essentially "falling" and thus it, and whatever is in it, is
experiencing zero Gs. (One G from gravity, counteracted by one G from
the accelleration.)

vince norris

[Hamish Reid]

In article >,
vincent p. norris > wrote:

> >> An SNJ doesn't "corkscrew" very much. It would hardly be
> >> enough to provide positive G in excess of 1.0.
> >
> >Well, the *whole point* of a textbook aileron roll is to maintain
> >positive G's -- not 1+ G's, but *positive* -- all the way through the
> >maneuver....
>
> Sorry, I didn't express myself well. I meant "It would hardly be
> enough to provide positive G in excess of 1.0, enough to negate the
> negative 1 G caused by gravity, plus a bit more to make it a positive
> G maneuver."

This is a little frustrating -- the standard aileron roll is done to
cause continuous positive G's. That's an *aim* of aileron rolls. And the
net G forces don't have to be more than 1, just enough to cause *net*
positive G forces on the pilot 9and engine, etc.). That's the
*definition* of a positive G maneuver.

This started when you stated that aileron rolls don't cause positive G's
all the way around, -- and that's just wrong, unless by "aileron roll"
you mean something different from what the IAC, various texts, etc., all
mean by the term.

> BTW, I looked again at a tape of Tex Johnston's rolls, going and
> coming. I cannot detect any "corkscrewing."

I can't comment on that except to say the corkscrewing is not always
obvious, especially from the ground... (I've never seen the videos, if
you're talking about the Dash-80 "barrell roll").

> > regardless of whether you do it in a Pitts or a puny Aerobat
> >(the Pitts is a lot more, erm, exciting in this respect :-)).
>
> I'm sure it is. I've had a little time in a friend's Starduster 2
> but never had the pleasure of flying a Pitts.
> >
> >> It does start with a slight pullup, but then then back-prssure on the
> >> stick is released, to produce what approximates a zero-G situation.
> >> (Don't you do that in an Aerobat?)
> >
> >The textbook aileron roll in an Aerobat starts with a shallow dive to
> >120 KIAS, then a smart pullup to 30 degrees pitch, then a quick
> >simultaneous full-over on the ailerons and neutralization of the
> >elevator until pullout. Apply rudder as appropriate...
>
> I would agree with that, except I neutralize the elevator THEN begin
> the roll.

Well, I'm lucky if I can get it all done at the same time :-).

> I don't think of the pullup as part of the maneurver, but as
> "preparation" for it.

It's a necessary part of achieving that ballistic corkscrew motion --
and (speaking from dumb experience) if you don't do the pullup properly,
you can end up in something more akin to a split-S or a nasty dive off
the end of the "roll", and / or a great deal of lost altitude.

> > In fact, it's close to 2G's at two points in
> >the maneuver (pullup and pullout), and it's probably around .5 to 1 G
> >over the top.
>
> I don't think of the pullup as part of the maneurver, but as
> "preparation" for it. I don't pull up that sharply, and if I have to
> "pull out" at the end, I figure I didn't do it right.

Well, the standard aileron roll typically has you pointing down at the
ground at much the same pitch at the 360 degree point that you started
the roll from (as a consequence of the corkscrew motion), so if you
don't do the pullup, you find yourself gaining speed very rapidly...

> If by "over the top" you mean when 180 degrees inverted, I find that
> very hard to imagine, based solely on my experience. (I've never
> flown an airplane with a G-meter.) I don't hang on the seat belt, as
> in a slow roll, but I feel a bit "weightless." I don't seem to be
> pushing down (up?) on the seat very hard.

For it to be a positive G maneuver, you don't have to be pushed down
very hard. Most people probably think it's negative G's when in fact
it's just reduced G's. Negative G's mean, yes, you're pressing up
against the straps....

> >Remember, half way around your altitude is still quite a bit higher than
> >it was when you started the maneuver....
>
> Yes, I think the airplane follows something like a "ballistic curve"
> during the maeuver.

Indeed -- the ballistic corkscrew curve is part of the definition of the
aileron roll I gave from Szurovy and Goulian earlier in this thread.
It's that motion that makes it a positive G maneuever. If, like me on a
typical day, you screw up and use the elevator or rudder wrongly, you
can certainly make it a negative G maneuver, but it stops being a real
aileron roll at that point (and starts becoming a cause for quick
roll-out-of-trouble action :-)).

>Certainly, it gets dang little vertical lift as
> it rolls past the 90 degree and 270 degree points.

It's not really supposed to.

> Despite the fact that the nose is pointed up slightly, the airplane is
> essentially "falling" and thus it, and whatever is in it, is
> experiencing zero Gs. (One G from gravity, counteracted by one G from
> the accelleration.)

No, the plane is experiencing *positive* G's in a decent aileron roll.
It's already starting to dive off the top at this point. Or should be,
if you're doing it right...

Hamish

[vincent p. norris]

>> Sorry, I didn't express myself well. I meant "It would hardly be
>> enough to provide positive G in excess of 1.0, enough to negate the
>> negative 1 G caused by gravity, plus a bit more to make it a positive
>> G maneuver."
>
>This is a little frustrating -- the standard aileron roll is done to
>cause continuous positive G's. That's an *aim* of aileron rolls.

I'm not trying to frustrate you, Hamish, but I don't agree with that.

I don't know if the aileron roll has any "purpose" or "aim" except to
have a little fun, and perhaps impress people who don't know how easy
and undemanding it is. It also puts minimum stress on the airplane.

Although an aileron roll can be done well, or badly, it's not a
precision maneuver. It wasn't even taught in navy flight training when
I went through. We learned to do slow rolls and barrel rolls to very
precise, very exacting, criteria, because it was *hard* to do them
that well, for a young pilot, and thus they developed our
stick-and-rudder skills.

>And the net G forces don't have to be more than 1, just enough to cause *net*
>positive G forces on the pilot 9and engine, etc.). That's the
>*definition* of a positive G maneuver.

That's what I said, above. But if an airplane is in inverted flight,
it takes at least 1.000001 positive Gs caused by acceleration to
overcome the negative G caused by gravity and produce a G sum that is
positive.
>
>This started when you stated that aileron rolls don't cause positive G's
>all the way around,

IIRC, I responded to a posting that said it was a "one G" maneuver,
which is what I disagreed with. Perhaps my memory is faulty on that
score.

>I can't comment on that except to say the corkscrewing is not always
>obvious, especially from the ground...

Seems to me that enough corkscrewing to produce at least 1 G of
accelleration when the airplane is inverted would be noticeable.
Think about what it takes to produce one G of acceleration in other
maneuvers.

>(I've never seen the videos, if you're talking about the Dash-80
"barrell roll").

Yes, that's the one. I've read Tex Johnston's book, and know it is
described there as a "barrel roll" and a "one G" maneuver. I strongly
suspect that wording was provided by the "ghost writer" who thought it
would sound impressive to the reading audience.

Whether one accepts the definition of a barrel roll supplied by Bob
Moore, a fellow naval aviator, or by, IIRC, "Big John," which is
radically different, each one produces very noticeable "corkscrewing"
and thus cannot be a one G maneuver.
>
>> >The textbook aileron roll in an Aerobat starts with a shallow dive to
>> >120 KIAS, then a smart pullup to 30 degrees pitch, then a quick
>> >simultaneous full-over on the ailerons and neutralization of the
>> >elevator until pullout. Apply rudder as appropriate...
>>
>> I would agree with that, except I neutralize the elevator THEN begin
>> the roll.
>
>Well, I'm lucky if I can get it all done at the same time :-).

OK, I'll accept that; in any case, the stick is "unloaded" while the
airplane is rolling.
>
>> I don't think of the pullup as part of the maneurver, but as
>> "preparation" for it.
>
>It's a necessary part of achieving that ballistic corkscrew motion --

In an Aerobat, I suppose it is necessary. In a more powerful
airplane, it is not. For example, an airplane capable of a steep
climb can nose over toward level flight and when his nose reaches the
desired point above the horizon, do an aileron roll. In fact, he can
do an aileron roll going straight up.

Similarly, low-powered airplanes, including the SNJ, generally need
to lower the nose to pick up a little speed to begin a loop. But that
is not part of the maneuver; more pwerful airplanes can do a loop
without lowering the nose, and it is perfectly correct loop.
>
>Indeed -- the ballistic corkscrew curve

That sounds like a contradiction. As I understand it, "ballistic"
refers to the trajectory of a shell after it leaves the muzzle of a
cannon, say, and is affected (in theory) only by gravity but in
actuality by air resistance, etc. It does not, so far as I know,
"corkscrew."

I believe the "Vomit Comet" describes a ballistic curve to produce a
weightless condition for budding astronoauts. No corkscrewing is
involved.

>>Certainly, it gets dang little vertical lift as
>> it rolls past the 90 degree and 270 degree points.
>
>It's not really supposed to.

That's right.
>
>> Despite the fact that the nose is pointed up slightly, the airplane is
>> essentially "falling" and thus it, and whatever is in it, is
>> experiencing zero Gs. (One G from gravity, counteracted by one G from
>> the accelleration.)
>
>No, the plane is experiencing *positive* G's in a decent aileron roll.
>It's already starting to dive off the top at this point. Or should be,
>if you're doing it right...

I'm afraid I disagree with that, too, Hamish. As I said eaarlier, if I
end up in a dive, I conclude I did it wrong.

I don't think we're ever going to agree about this, Hamish, so we
might as well just agree to disagree.

vince norris

[Hamish Reid]

In article >,
vincent p. norris > wrote:

[...]

> >And the net G forces don't have to be more than 1, just enough to cause
> >*net*
> >positive G forces on the pilot 9and engine, etc.). That's the
> >*definition* of a positive G maneuver.
>
> That's what I said, above. But if an airplane is in inverted flight,
> it takes at least 1.000001 positive Gs caused by acceleration to
> overcome the negative G caused by gravity and produce a G sum that is
> positive.
> >
> >This started when you stated that aileron rolls don't cause positive G's
> >all the way around,
>
> IIRC, I responded to a posting that said it was a "one G" maneuver,
> which is what I disagreed with. Perhaps my memory is faulty on that
> score.

Erm, well, we can stop right there, because that's what the problem
is... here's your article and my initial response (my stuff with the
single ">"):

>In article >,
vincent p. norris > wrote:

>>>Not if you maintain positive G all the way around (as in aileron
roll).
>>
>> You don't have positive G all the way around in an aileron roll.

>In a properly done aileron roll you certainly do...

>> To maintain positive G, you need a barrel roll.

>Or an aileron roll. Were you thinking of a slow roll?


And later in the thread I also explicitly asked whether you meant a "1G
maneuver" rather than a "positive G" maneuver. In both cases you said no.

Oh well. I think I kinda suspected this -- if you'd actually said it
wasn't a *1 G* maneuver, I'd have agreed wholeheartedly. But to make the
blanket statement that you don't have positive G all the way around in
an aileron roll (or any aileron roll), well, that ain't right....

Hamish

[Dylan Smith]

In article >, Big John wrote:
> From these figures you can see that it would be touch and go if you
> rolled the bird inverted. Of course the figures given are not ultimate
> so might only bend things a little :o)

But you'd have to really blow an aileron roll to pull enough negative
G to even reach the limit, let alone exceed it. So I dispute the
assertion that 99 times out of 100, you'd overstress a C172 doing
an aileron roll!

>>In article >, Big John wrote:
>>> On a 172,. I'd do a barrel roll in the bird but not a slow roll or
>>> aileron roll .Either would over stress the bird 99 times out of a
>>> hundred.


--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

[vincent p. norris]

>> >This started when you stated that aileron rolls don't cause positive G's
>> >all the way around,
>>
>> IIRC, I responded to a posting that said it was a "one G" maneuver,
>> which is what I disagreed with. Perhaps my memory is faulty on that
>> score.
>
>Erm, well, we can stop right there, because that's what the problem
>is... here's your article and my initial response (my stuff with the
>single ">"):
>
>>In article >,
> vincent p. norris > wrote:
>
>>>>Not if you maintain positive G all the way around (as in aileron
>roll).
>>>
>>> You don't have positive G all the way around in an aileron roll.

I believe that's essentially true.

As I said more recently,

>> But if an airplane is in inverted flight,
>> it takes at least 1.000001 positive Gs caused by acceleration to
>> overcome the negative G caused by gravity and produce a G sum that is
>> positive.

And I said that I have serious doubt there is enough "corkscrewing" in
the aileron rolls I've done, and seen others do, to produce more than
about 1 G. Maybe a bit less.

I would not suggest there are *noticeable* negative Gs, like a slow
roll; as I said, I don't hang on my seat belt. I think that halfway
through the roll, the airplane is *essentially* (i.e., for all
practical purposes) in a zero-G condition. I tried to say that
before, but perhaps I didn't say it well enough.

For that matter, when I "unload" the stick to begin the roll, I am
just about at zero Gs. I *attempt* to create a zero-G condition. I
believe that is the correct procedure. I'm sure I can't produce
exactly zero Gs every time, to several decimal places; no doubt I
sometimes produce a slight negative-G condition, sometimes a slight
positive-G condition.

Apparently you do not agree with that. I'm not suggesting you ought
to change the way you do aileron rolls, or think about them; I am
simply saying what I believe to be the case.

I've expressed my views several times, so I don't think there is much
to be gained by my repeating them again. We can just agree to
disagree.

>Oh well. I think I kinda suspected this -- if you'd actually said it
>wasn't a *1 G* maneuver, I'd have agreed wholeheartedly.

I imagine you would have. On that subject:

In a protracted discussion with a friend who is an aeronautical
engineer prof, specializing in aerodynamics, a year or so, in reaction
to an earlier thread on this newsgroup, we came to this conclusion:

"There is no such thing as a one-G maneuver."

An airplane flying straight and level, at constant speed, on a
smooth-air day, experiences one positive G.

ANY departure from that condition changes the G, either in amount, or
direction, or both.

Yet we often hear about "one G maneuvers." I think people use the
term to any maneuver that does not produce *palpable* G forces on
their bodies.

In that peculiar, inaccurate, sense, I suppose I would agree with the
statement that an aileron roll is a "one G maeuver."

vince norris

[Dylan Smith]

In article >, vincent p norris wrote:
> I would not suggest there are *noticeable* negative Gs, like a slow
> roll; as I said, I don't hang on my seat belt. I think that halfway
> through the roll, the airplane is *essentially* (i.e., for all
> practical purposes) in a zero-G condition. I tried to say that
> before, but perhaps I didn't say it well enough.

Correct me if I'm wrong (I've not had access to an aerobatic plane for
over a year) but the way I was taught to do them at least, you're
following essentially a ballistic trajectory whilst doing the roll,
so feel zero G as you go through inverted. That's what it felt like
to me at least - I never hung on the straps during an aileron roll
either.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

[vincent p. norris]

>Correct me if I'm wrong (I've not had access to an aerobatic plane for
>over a year) but the way I was taught to do them at least, you're
>following essentially a ballistic trajectory whilst doing the roll,
>so feel zero G as you go through inverted. That's what it felt like
>to me at least - I never hung on the straps during an aileron roll
>either.

I can't "correct" you, Dylan; I agree with you.

vince norris