My two cents:
I went searching for metal wings, and after studying the issue,
opted for cloth, hands-down.
My reason was (as confirmed by reviewing the weight data e-mails
recently posted) I could not see how anyone of standard weight could afford
change out cloth wings for metal ones. These birds are already right up at
their load limits for carrying two people. Under such circumstances, the
40-50 pounds added by metal covering is a big deal. That is why I
specifically did NOT make such a change out.
But, with respect to this, the American folks might note that
Europeans do not have the same level of familiarity with rag wings or
fuselage structures. Though it has stayed vibrant and technologically
current in the US, largely due, I think, to our huge numbers of
"experimental aircraft", nobody else has the benefit of such familiarity.
For those without such familiarity:
-It is not intuitively obvious that metal wings will have a measurable
negative effect on flight performance, if from nothing but weight alone, but
it is factual.
-It is not intuitively obvious that the extra weight of metal may actually
decrease the ability of the stucture to deal with g-loads, but still is
factual.
-It is not intuitively obvious that metal is subject to stress fractures
that cloth will never experience, but it is still factual.
Blue side up. Brown side down.
=========]-(ยง)-[==========
// \\
Dave W
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: Friday, 11 September, 2009 7:16 AM
To: [email protected]
Subject: [ercoupe-tech] Re: Metal Wings are stronger.....
I think the statement that "metal wings are stronger" is a generalization
when we're talking about the Ercoupe. An airplane designed with metal wings
CAN be stronger and we have many examples of airplanes that are, fron the
DC-3 to the 747. Many engineering factors go into wing design, including
g-stress and wing loading. To assume that metal wings on an Ercoupe are
inherently "stronger" is probably a fallacy. The internal structure is
responsible for load-bearing on our airplanes, and any additional strength
from the covering medium is incidental. Reasons to favor one covering medium
over another could be exposure to the environment, maintainability,
cosmetics, and cost. That's a valid debate, and anyone choosing metal or
fabric should consider those and make the best choice for their
circumstances. But choosing metal over fabric based on strength is simply a
false choice, IMO.
By the way, the B-52 I flew had metal wings and was a 2 G aircraft. My B-1
had metal wings and was a 3 G aircraft. My Ercoupe is rated at 3.5 G's so I
could make the argument that "fabric Ercoupe wings are stronger". We all
know that's not the case, and that many other factors go into max G loading
and wing design.
Dave
