On Sun, 23 Jul 2006 14:00:37 GMT, Matt Whiting
wrote in ::

Larry Dighera wrote:

On Sun, 23 Jul 2006 01:54:35 GMT, Matt Whiting
wrote in ::


Flight load factor

Flaps up = +4.4 G's and -1.76 G's


So, in inverted flight a C-172 has only a 76% of a G margin to carry
additional G force. That isn't much.

Thanks.

No, 176% of a G.


No. A _margin_ of only a 76% of a G to carry G forces in addition to
the one G natural force.

When you are pulling negative G, there is no one natural G force.

While you are in the vicinity of the Earth, your aircraft is being
acted upon by the Earth's one G gravitational force.

If you are flying straight and level while inverted, the airframe is
experiencing -1G, not 0 G.

That provides the remaining 0.76 (76%) of a G of the C-172's negative
load factor specification of -1.76 to carry the load of any
acceleration that may subsequently occur.

It takes -1 G of acceleration to counter gravity and get you to 0 G.

Agreed.

You can then add -1.76 G of additional acceleration and still be within load
limits.

That analysis presumes the aircraft is not inverted.

The negative G load factor is referenced to 0 G, not 1 G
straight and level.

Are not both the positive and negative load factors referenced to 0 G?
You don't set your G-meter to 0 when you are on the taxiway; you set
it to read 1 G, right?

We were discussing the negative load that might be encountered during
the inverted recovery from a barrel roll, so the earth's gravity would
add to any accelerative force while the aircraft is inverted, right?