Rolling a 172 - or not

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.

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

"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.

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

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

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

"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

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.
)


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----

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

"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