Andrew Rowley wrote in message . ..
(Koopas Ly) wrote:

I think I understand now. Let me see if I get it...

To rework the analysis, I'll assume that the weight of the airplane is
mainly supported by the wings, and that other components such as the
engine mount are essentially invariant in static 1g weight. In other
words, by overloading the airplane with other bodies, ballast, and
such, the weight of the engine mount does not change. If that is so,
I can see how such *individual* components may be "g limited" with
respect to their own inertia. Does this follow your reasoning?

almost... the engine mount needs to support the weight of the engine
multiplied by the number of Gs. so if the engine weighs 100kg at 3.8G
the mount is supporting 380kg. At 5G it has to support 500kg. So force
on the wings at high Gs may go down as your total weight goes down,
but the force on other items (engine mount, baggage floor, basically
any part of the airframe that has to support something) does not.

The engine mount on most light aircraft is designed to withstand 9
G's minimum. And as I said earlier, the 3.8 figure is based on gross
weight. Reducing gross would allow them to take a higher G figure but
the same net force.
Cessna also states in the 172 POH that it's designed to 150% of
the G figures given, or 5.7 G's. I think the 3.8 figure would be the
yield point, where things begin to bend, and the 150% figure would
break them entirely. Or something like that.

Dan