Re: spar caps
I am delighted that I am not the only one whose alarm bells are
beginning to sound like tinnitus.
That said, Larry has illustrated my previous assertions beautifully.
The problem is that some poor souls still think that this
discontinuous outpouring is justification for the most dangerous
You make the best of points when you highlight the actual strength of
the materials which result from the wet layup process. The safety
margins are eroded before the part is cured.
Gentlemen, please ignore Larry's advice. It is just plain (and plane)
I am presently revisiting the calcs to illustrate how close to the
edge the 1000 lb loading is to the limit and the dangers of overload.
I will restate the critical point that irrespective of the canard
strength, it is the weakest link that will fail and the result will be
The headstone manufacture will not care one jot if it was a wing
failure or a canard failure that proved one's undoing...
--- In Q-LIST@..., oneskydog@... wrote:
designer you hold lives in your hand. When you fix a damaged partoriginal
materials must be used to restore the laminate to the designspecifications to
restore just the right amount of strength and stiffness. Unless youhave a note
from Burt do not redesign these planes you are in way over yourhead. Your
mumbo jumbo with terms like using stiffness when it should bestrength, using
laminate strength claims made in a catalog as "A"basis allowable'sto do your
back of the envelope section calculations make me nervous. I havealso seen
the quality of your repairs on the flipped Tri-Q and frankly wasalarmed. I
cannot sit silent and let you preach design mods to the builders.repair
but am not qualified to design composite parts. In one class thestudents build
a carbon fiber "I" beam from unidirectional pre-impregnated carbonfiber
tape. They also have to calculate the strength and first ply failureand predict
the maximum load the beam will take. We then take the beams to thetest lab
and using a really cool 4 point bend fixture we crush the living**** out of
them. The students who are engineers are always surprised at thespread
between the predicted and the actual values0.130 inches
thick with 19 unidirectional plies for tension/compression. Theoverall beam is
3" high and 3" wide so we are in the range of a Q canard sectionsomewhere
between the root and tip.variance
for the same laminate built on hard tooling vacuum bagged andautoclave
cured. More sobering is that it is not even close to 30 G's if yourworking load
is a thousand pounds. You cannot duplicate the quality of theseparts in your
garage or hanger and we haven't even talked about adhesively bondedjoints.
what a gazillion hours and a ME degree but are you a practicingcomposites
structural designer? Playing composite airplane designer getspeople killed and
maimed. Follow the dammed plans for your structural parts, exerciseyour
creativity on tertiary structure and finish.people.
Awards. Go to AOL Music.