Myth: 1 G barrel rolls are impossible.

On Mon, 11 Jun 2007 22:24:02 -0000, Jim Logajan
wrote:

Mxsmanic wrote:
Jim Logajan writes:

Most everyone agrees that keeping the coffee in the cup is possible.
What some people don't seem to believe is possible is that the force
felt by the pilot (or tea/coffee) can be 1 gee during the entire
roll. They believe it has to vary during the roll. I'm hesitant to
name names. ;-)

It has to vary during the roll, because the constant 1 G acceleration
due to gravity does not change. The net acceleration of the aircraft
must always be at least one G in consequence, and if the aircraft
begins a climb or ends a descent, it _must_ be greater than +1.0 G.

Sigh. Yes, the force that is felt is greater then one g-force at the
beginning and end of the maneuver. But that is not the case "during the
roll" itself. Again, as in the other post of yours I responded to, you
appear to be confusing force and acceleration.

Not a serious confusion, as force and acceleration are stricly
proportional (F=mA) as long as the mass of the object (plane) is not
changing. Over the time intervals involved, not enough fuel is burned
to significantly change the mass. Now, if the pilot scares the s--t
out of himself during the manouver, then the proportionality might not
hold up. :-)
---
Jay (remove dashes for legal email address)