On Fri, 21 Jul 2006 23:10:46 GMT, "Dudley Henriques"
wrote:


"Big John" wrote in message
.. .
Dudley

Can it be said?

In a Barrel Roll the ball starts centered and stays centered
throughout the roll until aircraft returns to straight and level
flight and starts some other maneuver.

If you are good, you can fly a barrel roll center ball. This requires a near
perfect blend of all controls and is the right way to do the classic BR.

In a Slow Roll (sometimes called Point Roll) the ball starts centered
and is then never centered except momentarily when bird has rolled 180
degrees and is inverted, until completion of roll and return to
straight and level flight?

Well...almost :-) You might lose the center ball as you pull to the roll set
point but in theory it should remain more of less centered up till roll
initiation. Immediately after you initiate a slow roll, you will lose a
center ball as all control input through a slow roll is done in a constantly
changing cross control dynamic. In theory, you should have a doghouse ball
passing through the exact inverted point, but what actually is happening at
this point is that you will be changing rudder to regain top rudder on the
back side, so the airplane will be in a state of transition even through
exact inverted.
Personally, I never used a ball at all in aerobatics and I don't recommend
using a ball to other aerobatic instructors. One of the benefits involved in
learning to fly acro is that you learn to judge maneuver quality with your
eyeballs on the nose attitude outside the airplane . All positioning is
eyeball related and any unwanted yaw should be immediately apparent by
watching the nose.
I discourage ball use even in primary students, and get their heads outside
where it belongs as soon as possible.
All pilots should learn as soon as possible to judge turn quality from nose
attitude behavior.
I know many...many aerobatic pilots who take the ball out of their airplanes
simply to save the weight and space the instrument takes up on the panel.


Rolls are easy to explain face to face in briefing using hands or
models and demo in air, but over Internet the nuances of English make
it difficult.

This can be quite true.

Dudley Henriques


Big John
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On Fri, 21 Jul 2006 14:43:10 GMT, "Dudley Henriques"
wrote:

Ron;
I think what might be happening here is that some folks are defining the
roll from the set point rather than from level flight. It's true that any
raising of the nose from level flight will require more than 1 g, but once
at the set point and initiating the roll (aileron roll) you can unload the
airplane all the way down to 0 g if you like right up to the backside
recovery to level flight, where the g of course has to be returned.
Dudley Henriques

"Ron Natalie" wrote in message
.com...
Big John wrote:
Andrey

As has been said in all the posts, the short answer is NO. 172 is not
certified to do barrel rolls.

However I can barrel roll a 172 only pulling 1 G which puts no more
load on airframe than straight and level flight. I have thousands of
hours to back up my statement.

No you can not.

It's not possible to even start the roll without going greater
than 1G.

Preface: I'm an IAC member and have been flying competitions since '95
in Yaks, Sukhois and Extras and also in unlimited gliders. I have
also held an FAA form 8710-7 card for air shows. (not current)

This morning I went out to play with some barrel rolls in the Extra
300. I'd like to offer that no one has yet mentioned that you can fly
very different sorts of barrel rolls where the main variable is the
amount the nose deflects from level flight. I think the "fighter
pilot" sort of barrel roll that is done to avoid overshooting an
opponent or to cause a following opponent to overshoot you is
typically done with not so much upward and downward nose deflection
from level. If you start an aileron roll and add in just a touch of
back stick at the beginning and end with a bit of push while inverted,
you'll fly a very tight barrel roll with minimal nose deflection. On
the other hand, if you use a lot of nose deflection so that the nose
goes all the way to vertical, you make a very different looking
barrel roll. THIS is the barrel roll that you can say is a
combination of a roll and a loop.

People are claiming 1 g barrel rolls can be performed. Nope. Not if
you are starting and ending in level flight. On a ballistic
trajectory, maybe. This is especially true for the big barrel roll
which can be said to be a combined roll and loop. A round loop
requires at least 3.5 - 4 g. I usually use around 6 g at the
beginning and end of my loops to make them look nice and round. To
get a similar barrel roll requires similar g levels.

It has been said in this thread that "there is no competition barrel
roll". That is about half true. There used to be (long before I got
into it) a competition barrel roll but it was deleted from the
catalog. The current catalog of figures has a pair of figures called
"quarter clovers". Each of these consist of half a barrel roll and
half of a loop. In one, as you pull into a loop, you put in some
aileron. You continue with the rolling until you reach the top of the
loop. At this point, you are inverted, level and have turned the nose
90 degrees from the original flight direction. You then center the
ailerons and fly the bottom half of a loop back to straight and level.
The other quarter clover is done in the opposite manner, i.e., the
first half of the figure is a half loop with no rolling. The second
half of the figure combines aileron input with elevator to return to
straight and level upright flight but with a 90 degree heading change
from the original direction of flight.

I think these are called quarter clovers because if you did four of
them in succession with the smoke on, (and no wind) you'd make a nice
4-leaf clover figure in the sky.

If you performed the first half of the first quarter clover and the
second half from the second quarter clover, with the same aileron
deflection on both halves, you'd fly the classic really big barrel
roll.

These figures were first used for aerobatic glider competitions and
then were also recently used in the Sportsman "known" sequence. I've
never seen them flown at higher levels of competition.

Many times, competitors are downgraded for "barreling" a "slow" roll.
Note that the word slow means nothing for the speed of rolling. In a
slow roll the fuselage does not deflect during the roll. An aileron
roll is one where you begin with a pull to get some nose up
deflection, followed by a return to 1 g (or less) and the aileron
deflection to roll about the longitudinal axis. After return to wings
level, the nose may have dropped below horizontal and will need a
little pull to return to level. A fast rolling airplane (like a
Sukhoi or Extra) can complete the roll so quickly that the aileron
roll and slow roll look the same and are performed the same. A
barreled roll would have discernable nose deflection during the course
of the roll. Most competitors have this happen to them on the last
half of a full roll. This defect is also called "dished". I think it
usually happens because the pilot uses inadequate push while inverted,
allowing the nose to drop from the horizontal. If doing it at low
level, you can find yourself at zero altitude (or less), as Dudley has
pointed out. :-(

In unlimited glider aerobatic competitions there is a figure called
the "super slow roll" where a 360 degree roll must take AT LEAST 10
seconds to perform. The chief judge times you and if you do it too
fast, you "zero" the figure. Or course, there is lots of opportunity
for every little defect in technique to become obvious to the judges.

A "point" roll is one where the rolling is stopped briefly and
restarted one or more times - also sometimes called a "hesitation
roll". E.g., a four point roll would consist of 4 - 90 degree rolls
in the same direction with a brief pause between each of the 90 degree
rolls for a total of 360 degrees of rolling to get back to the
starting attitude.

I agree with the point made about using the ball during acro. I never
look at mine and my aerobatic glider doesn't even have one. Doesn't
have a yaw string either. :-0 I don't need it.

Happy landings,
Klein