Myth: 1 G barrel rolls are impossible.

wrote:
Hang on, let's keep things simple:

1. If I enter a coordinated turn, I experience an increase in Gs.
2. If I enter a descent, I experience a decrease in Gs.

If I do these two things at the same time, it is possible to enter a
descending turn without any change in Gs. Just as long as I
continously feed in enough down elevator to offset the increasing Gs
from the turn, the force on the airframe and me, the pilot, will stay
at 1 G.

Of course, all combinations are indeed possible. But this interesting
special case of the situation exists, doesn't it, in which there is no
change in the force felt by the pilot?


On Jun 14, 3:36 pm, Mxsmanic wrote:
writes:
'Some combination', 'several possibilities.' I'm confused by this -
can you be more precise? What are the possibilities?
You can move and accelerate in any combination of three dimensions, with any
combination of acceleration rates, almost. You have to calculate the
direction and magnitude of the net acceleration vector to determine exactly
how much force is acting upon the pilot, and in which direction.

Some of it is (or should be) intuitive. For example, if you turn the aircraft
to the right, you'll be accelerated to the right.


There is a special case where you can unload the airplane in roll to
increase the roll rate. It's done in fighters all the time in ACM. You
can experience it in your everyday light aerobatic airplane by doing an
aileron roll from a nose high roll set position, then as the airplane
goes past the first knife edge position, go forward on the pole to
unload the wings but not enough to go negative. Keeping the aileron in
hard while you do this increases the roll rate and as a side effect
flattens the roll in pitch at the same time making it prettier :-)

Dudley Henriques

Dudley Henriques wrote:

There is a special case where you can unload the airplane in roll to
increase the roll rate. It's done in fighters all the time in ACM. You
can experience it in your everyday light aerobatic airplane by doing an
aileron roll from a nose high roll set position, then as the airplane
goes past the first knife edge position, go forward on the pole to
unload the wings but not enough to go negative. Keeping the aileron in
hard while you do this increases the roll rate and as a side effect
flattens the roll in pitch at the same time making it prettier :-)

Why does this work?

Matt

Matt Whiting wrote:
Dudley Henriques wrote:

There is a special case where you can unload the airplane in roll to
increase the roll rate. It's done in fighters all the time in ACM. You
can experience it in your everyday light aerobatic airplane by doing
an aileron roll from a nose high roll set position, then as the
airplane goes past the first knife edge position, go forward on the
pole to unload the wings but not enough to go negative. Keeping the
aileron in hard while you do this increases the roll rate and as a
side effect flattens the roll in pitch at the same time making it
prettier :-)

Why does this work?

Matt

Several factors effect roll rate, roll acceleration and roll inertia.
Basically why this works is that unloading the airplane while rolling
(aileron roll basically, not a slow roll) minimizes much of the
effectiveness issues experienced by the ailerons especially at low
airspeeds and high load factors when the wings are generating a fair
amount of lift. Anytime you want to maximize the roll rate, unloading
will achieve this. The exact point where the rate is maximized by
unloading will vary from aircraft to aircraft but basically the rule
still applies.
Dudley Henriques

Dudley Henriques wrote:
Matt Whiting wrote:
Dudley Henriques wrote:

There is a special case where you can unload the airplane in roll to
increase the roll rate. It's done in fighters all the time in ACM.
You can experience it in your everyday light aerobatic airplane by
doing an aileron roll from a nose high roll set position, then as the
airplane goes past the first knife edge position, go forward on the
pole to unload the wings but not enough to go negative. Keeping the
aileron in hard while you do this increases the roll rate and as a
side effect flattens the roll in pitch at the same time making it
prettier :-)

Why does this work?

Matt

Several factors effect roll rate, roll acceleration and roll inertia.
Basically why this works is that unloading the airplane while rolling
(aileron roll basically, not a slow roll) minimizes much of the
effectiveness issues experienced by the ailerons especially at low
airspeeds and high load factors when the wings are generating a fair
amount of lift. Anytime you want to maximize the roll rate, unloading
will achieve this. The exact point where the rate is maximized by
unloading will vary from aircraft to aircraft but basically the rule
still applies.
Dudley Henriques

Thanks!