On May 10, 3:20 pm, Matt Whiting wrote:
Paul Tomblin wrote:
In a previous article, Erik said:
Sheista wrote:
http://www.thepollspace.com/polls.php?pollid=1359



I know this already, but it always amazes me to see
the wing holding up the plane. It's propped off of
the ground on the one wing. I know this happens in
the air, it's just neat to see how strong the wings
actually are.

In the air, the load is distributed along the length of the wing, rather
than just on the wing tip. So this wing is taking more torque than a wing
in the air.

Only if you consider an air load of 1G. I'd have to do that calculation
to be sure, but I'm fairly confident that 4G in the air is more moment
at the wing root than is 1G at the tip.

Matt- Hide quoted text -

- Show quoted text -

I'm not sure how actual aircraft engineers do it but when I got my
engineering degree that isn't how we would do it. Looking at the
moment at the root seems to imply that the entire length of the wing
is of equal strength and the forces are focused on the root. In fact
the wing is not designed to be equal strength throughout, each section
of the wing is only as strong as it needs to be. Therefore, the chance
of failure (at least ideally) is about equal anywhere along the wing
(root, mid section, tip, etc). There may be practical frabrication
reasons why you would have one section of a wing "over engineered",
but in general, that would not be an engineer's goal.

When I was an engineering student we would look at each spar's forces
as a continous function using calc. That way we could use dx to see
the force on any infinite small section of each spar. Looking at the
max force at any dx we could reduce weight (i.e. strength) if one
section was stronger than necessary. The strength at that section
would be designed to meet the requirement of the force expected. I.e.
we wouldn't make the entire wing the same strength if the forces were
not the same throughout.

-Robert