"Dudley Henriques" wrote in message
news:2007061101084716807-dhenriques@rcncom...

Bertie is correct. Barrel Rolls are perhaps the most misquoted and
misunderstood maneuver done in an airplane.
Basically, you can do a barrel roll as loosely or as tight as the
airplane's flight envelope will allow. You can also enter a BR from many
different flight conditions involving many different g loadings.
The main thing to remember about barrel rolls is that they are a 3
dimensional maneuver through 3 dimensional space and that the common
denominator in a barrel roll regardless of the g used is that it will
remain POSITIVE all the way around. The one exception to this would be
after the pull and roll application, you can unload the airplane over the
top and drop the g to +1 if you like to loosen the roll rate, but that g
must be regained during the recovery.
Basically, you will be somewhere over +1g in the entry as you raise the
nose, then at some positive +g throughout the roll ranging from as
unloaded as you want to loosen up the airplane or as high a positive g and
tight a roll as the envelope will allow. As long as the airplane
transverses 3 dimensions through the roll, it's a barrel roll.
I've done them as loose as a 90 degree change of direction at the top apex
in a P51,the F8F, and several jets including the T38, and as tight as a
corkscrew in a Pitts S1Sl which was highly loaded with +g and extremely
tight.
Bob Hoover's rather famous Iced tea stunt in the Shrike is probably
responsible for much of the misconception about barrel rolls. He does them
fairly loose and with just enough positive g on the airplane to keep the
glass from spilling without stressing the airplane. The "secret" to Bob's
tea trick is simply his smoothness through the roll as much as keeping
positive g on the tea. It's really this smoothness that makes this stunt
possible, as although positive g will keep the tea inside the glass. (You
can actually POUR tea as you're rolling the airplane but ONLY if you're
as smooth as Hoover :-)
The reason smoothness is so necessary for the tea trick is that even
though you might have positive g on the airplane and in effect doing a
barrel roll, if you are not perfectly coordinated through the roll (any
excessive yaw for example) your tea will slide off the glare shield
laterally and you don't want that......not if you're Bob Hoover anyway :-)
So it's positive g for the roll, and smoothness and perfect coordination
for the tea stunt.

I'm not talking about Bob's tea trick. Obvoiusly, positive Gs and
coordination is the key there. And I'm not sure I understand or agree with
your post. But I think it might be possible we having a terminology issue
here with the definition of a barrel roll.

I fully admit barrel rolls as defined by most pilots require more than
"exactly 1g", and usually a little negative, depending on the desired flight
path. Also, doing a near 1g roll as I mentioned, more than 1g will be
required to set up the manuver, and return to level flight afterwards. But I
disagree that it one needs to deviate much from 1g to roll the wings of an
aircraft 360 degrees if flying an arc. Depending on the arc and corkscrew of
your flight path, you can roll with very little if not no stress on the
aircraft.