Path of an airplane in a 1G roll

A properly performed barrel roll is a 1G manuever. The aircraft's
flight path describes a helix, as David described below. An aileron
roll is a variable-G operation, since you feel -1G while inverted.

CB wrote:
A properly performed barrel roll is a 1G manuever.

Nope. It's a small amount of positive G's but it's not a constant
1G. Did you actually read David's post?

"CB" wrote
A properly performed barrel roll is a 1G manuever. The aircraft's
flight path describes a helix, as David described below. An aileron
roll is a variable-G operation, since you feel -1G while inverted.

Check the following web sites, they all contain the same paragraph.
Care to give us your references for the definition of a barrel roll.

http://www.iac.org/begin/figures.html#Barrel%20Rolls
http://acro.harvard.edu
http://web.winco.net/~efildes/slowroll/barlroll.html
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.

Bob Moore

On Wed, 22 Jun 2005 at 20:09:25 in message
, Bob Moore
wrote:
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.

That must of course be correct. To describe an actual horizontal helix
would require a lot of smooth changes in g and in necessary control
deflections, otherwise the helix would not be circular in cross section.

However perhaps there could be a manoeuvre that combines a roll with a
constant 1 g pressure on the crew?

My guess is that it would turn into rather odd sort of spiral dive. The
nose would certainly fall below a level flight path!
--
David CL Francis

Just to add to all of this about if a barrel roll is a 1G maneuver, which I
don't think it is, I was watch a Military Channel show on Boeing and
the -80/707 and Tex Johnston was talking about the barrel roll he did and
said it was a 1G maneuver.




"David CL Francis" wrote in message
...
On Wed, 22 Jun 2005 at 20:09:25 in message
, Bob Moore
wrote:
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.

That must of course be correct. To describe an actual horizontal helix
would require a lot of smooth changes in g and in necessary control
deflections, otherwise the helix would not be circular in cross section.

However perhaps there could be a manoeuvre that combines a roll with a
constant 1 g pressure on the crew?

My guess is that it would turn into rather odd sort of spiral dive. The
nose would certainly fall below a level flight path!
--
David CL Francis

On Fri, 24 Jun 2005 13:08:09 -0500, "Gig 601XL Builder"
wr.giacona@coxDOTnet wrote:

Just to add to all of this about if a barrel roll is a 1G maneuver, which I
don't think it is, I was watch a Military Channel show on Boeing and
the -80/707 and Tex Johnston was talking about the barrel roll he did and
said it was a 1G maneuver.

Think about it, sitting at the keyboard typing, and flying along in
level flight, you are at 1G. Pull back on the yoke or stick and you
are no longer at 1G, you are at 1G plus whatever it takes to climb.
It's impossible to gain altitude without experiencing more than 1G.

Could it be that the person describing the 707 barrel roll meant that
the maneuver was 1G in excess of 1G? In other words 2G's? Could be,
but probably the announcer or "talent" speaking for the clip had no
idea what he was talking about.

Corky Scott

Corky Scott writes:
Could it be that the person describing the 707 barrel roll meant that
the maneuver was 1G in excess of 1G? In other words 2G's? Could be,
but probably the announcer or "talent" speaking for the clip had no
idea what he was talking about.

Actually, I think Tex says it. You can watch the video clip yourself
and make up your mind, Jay has it archived on this page:

http://www.alexisparkinn.com/aviation_videos.htm

Search for "Tex" and you'll find it.

Chris
--
Chris Colohan Email: PGP: finger
Web: www.colohan.com Phone: (412)268-4751

"Corky Scott" wrote in message
...
On Fri, 24 Jun 2005 13:08:09 -0500, "Gig 601XL Builder"
wr.giacona@coxDOTnet wrote:

Just to add to all of this about if a barrel roll is a 1G maneuver, which
I
don't think it is, I was watch a Military Channel show on Boeing and
the -80/707 and Tex Johnston was talking about the barrel roll he did and
said it was a 1G maneuver.

Think about it, sitting at the keyboard typing, and flying along in
level flight, you are at 1G. Pull back on the yoke or stick and you
are no longer at 1G, you are at 1G plus whatever it takes to climb.
It's impossible to gain altitude without experiencing more than 1G.

Could it be that the person describing the 707 barrel roll meant that
the maneuver was 1G in excess of 1G? In other words 2G's? Could be,
but probably the announcer or "talent" speaking for the clip had no
idea what he was talking about.

Corky Scott

Well Corkster, don't tell me tell Tex Johnston. He did it and he said it. As
I said in my post I don't think it is a 1G maneuver and for that mater it
wasn't a very good barrel roll except when you consider it had never been
done in that model of airplane and even the co-pilot didn't know he was
going to do it until right before he did it.

Gig G

Not to put too fine a point on this, Corky, but you can in fact enter a
climb and still maintain 1 G downward relative to the axis of the
airplane, but you have to decelerate while starting the climb. I agree
that you can't climb at a steady rate and not experience a shift in g
forces aft, but as your bring the nose up you have to slow down as
well, to add a little negative acceleration to offset the aft shifting
gravity vector. Think of it this way. If you hang a plumb bob in the
airplane, and start a climb, the bob will shift aft. If you're in level
flight and slow down, it'll shift forward. If you combine the two
correctly, it'll stay pointing at the same spot on the floor.

If you agree with this reasoning, you'll also agree that with a fast
enough entry speed you could pull through an entire loop -- it wouldn't
be round! -- and keep the plumb bob centered over the same spot.

Think about it, sitting at the keyboard typing, and flying along in
level flight, you are at 1G. Pull back on the yoke or stick and you
are no longer at 1G, you are at 1G plus whatever it takes to climb.
It's impossible to gain altitude without experiencing more than 1G.

Could it be that the person describing the 707 barrel roll meant that
the maneuver was 1G in excess of 1G? In other words 2G's? Could be,
but probably the announcer or "talent" speaking for the clip had no
idea what he was talking about.

If you hang a plumb bob in the
airplane, and start a climb, the bob will shift aft. If you're in level
flight and slow down, it'll shift forward. If you combine the two
correctly, it'll stay pointing at the same spot on the floor.

.... and the string will break.

Or at least will be under more stress. There's more than the position
of the plumb bob to the total net force.

Jose
--
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