"Gordon Arnaut" wrote

I'm posting this for the normal people in this group who might thing that
this "Morgans" clown actually has some kind of valid point.

OK, I tried nice, but you don't want to play, so first of all, a general,
FYT.

His remarks make quite clear that he doesn't know the first thing about
structures. Yet he comes out with guns blazing and hurling unprovoked
insults. What a clown.

For example, take his comment about modulus of rupture not being relevant
to stress in compression or tension.

In contex, if you please. Site the usage, please. I can't defend something
I don't see.

This is complete gibberish that shows he doesn't understand even the
basics. Modulus of rupture is a measure of a material's strength in
bending.

Close. That is when it FAILS.

Bending loads on a piece of wood (or other material) typically produce
stress in both compression and tension at the same time.

Oh really? Why that's all new news to this clown. Wow, thanks.

Take a wood yardstick and hold it by the ends; now try to bend it into a U
shape. The wood fibers on the inside of the curve will be in compression,
while those on the outside will be in tension, simultaneously.

If you apply enough bending moment you can break the stick. But what if
you bend it as far as you can without breaking it and then let it go? Have
you done any damage?

Depends.

Please tell us how you can tell. Give us all a REAL example. Use something
more than modulus of rupture, or buy a vowel.

It's quite possible tthat you have damaged the wood fibers that were in
compression (the top of the stick). Almost certainly you will not have
damaged the bottom of the stick, which was under tension.

Really? How do you know? There are ways to know, or don't you know how to
figure that part?

So while you didn't break the stick, you might have caused compression
failure on the side of the stick that was on the inside of the curve. This
damage would be most acute on the top surface of the stick and would be
progressivly less until the neutral axis (middle) of the stick.

If you made a saw cut right across the point of bending, you would
probably see -- under a magnifying glass -- wood fibers that have failed
in compression.

Don't need a magnifying glass, if you know what to look for.

Idiot's comments about needing 10,000 pounds on top of the wood simply
illustrate to everyone what a loudmouth know-nothing he is.

I was talking about a bending force, or can't you read?

All it takes is enough force to bend the plank more than you would
normally do.

Oh, please tell. How about that. How about a number a bit more specific
than "more than you would normally do." How much is normal? Those numbers
are in there.

This does not have to be a lot of force.

Once again, something more specific, please, professor? No? Oh well. You
obviously show a lot more book knowledge than real application.

You had damn well better understand how all of the figures for each species
apply to how the specific stick will be used. You know nothing that anyone
here should use to build an airplane.

You said something back there about modulus of rupture being the most
important. Yes it is important, but far from _all_ that is important.

How about modulus of elasticity? Some woods will not bend much, until they
suddenly rupture. Might want to know that, right? Some woods are very poor
in tension, and splinter at the drop of a hat. Might want to know about
that, too.

YOU CAN NOT PICK AND CHOOSE WHAT FIGURES YOU WANT TO LOOK AT. YOU MUST USE
THEM ALL, AND UNDERSTAND HOW TO USE THEM ALL.

To say otherwise is to create a death trap, and irresponsible to try to
convince others, that you don't need to consider the loads that will be
placed on each individual part.

Most people do not have the skills and understanding to consider all of the
factors involved. It is VERY clear, at least you do not.

YOU are one more fine example of newsgroups "gods" spouting off, and giving
misinformation that could be deadly.

Ever read the government's forrest products book? It's old, but still the
best of its type. Try it. That is only a start.

By the way, so everyone out there in newsgroup land can best judge how you
are qualified to pass on all of your useful information, how about posting
all of your qualifications? Education, degrees, how many wood airframes you
have analyzed, how many you have built and flown? Any or all of those
things.

Please. Please. Use the Doctor's motto. First do no harm.

You have some un-doing to do.

Don't bother responding to me. You are off my radar; my blood pressure
can't stand it.

Please, group. Learn more from someone who knows more than him (or me)
before taking this one's advise.

Jerk. I hate being like this.
--
Jim in NC