Load Limits: Confessions of an Obsessive Compulsive Nerd


Mike Perry <dmperry1012@...>
 

Recently I produced a set of files designed to help people using Q200s at
gross weight over 1100 lbs. (Now posted on Jon Finley's website as
Q200_POH_supplement.zip) That drew questions on and off list about Marc
Waddelow's analysis of the wing and the allegedly marginal strength of the
main wing. Meanwhile Larry Severson keeps posting a claim that the Q2
canard was designed to 30Gs. Last nite and this AM I re-read everything I
can find on Waddelow's analysis and all the old materials I have on the
Q2xx from QAC and others. Here is my summary:

I did locate one statement supporting the 30G design of the canard, along
with some other interesting information:

Lightweight does not, however, imply low structural margins; at the drawing
board stage, the Q2 rear wing was designed for a positive 12G limit load
and the canard, since it doubles as the main landing gear is required to
withstand over 30G's of positive inflight loads and a 500 ft./min. landing
impact. (Sport Aviation, May 1981, as reprinted by QAC for distribution as
advertising)

The only documentation I have of Marc Waddelow's analysis of the wing is in
Quicktalk # 28, pp 9-10. This is a summary of an exchange of letters
between Marc and Gene Sheehan. To summarize two pages of material, the
more detailed Marc's analysis, the closer he got to Sheehan's numbers. I
have no doubt Marc had a better design, but I think it was only slightly
better. If anyone has more information I am interested. Read the
newsletter, it's too long to reproduce here.

One quote from Sheehan: "As to your [Waddelow's] suggested modifications I
can't see anything wrong with them other than an increase in weight. This
may seem to be a small matter to you but my experience has shown that the
typical homebuilder who doesn't trust the designer and adds a little beef
here and there usually ends up with a very heavy airplane. He also insists
on flying over gross weight. So instead of having a stronger airplane he
may actually have less margin. . . "

Furthermore, Sheehan reported non-destructive testing to 8Gs, and
recommended any modification of the main wing or canard be tested to "at
least 50% above what you wish to use as your limit G loading."

I did not find any documentation of testing to actual limits; that is, no
one built a wing and loaded it until it broke. I think QAC should have,
but they didn't.

We do have other data: there are some amazingly heavy Quickies
flying. Some Q2xxs were built with O235s, full panels, design mods and the
kitchen sink. I have Larry Koutz's listing of flying Qs in the USA,
probably from about year 2000. There are several planes with empty weights
over 825 lbs! Charlie Harris of Littleton Colorado has a Q200 weighing 832
lbs with 1000 hours.

Then we have the Weight and Balance info sent with my kit, showing a gross
of 1300. There is no testing or engineering documentation to support this
that I am aware of.

All this suggests to me the wing structure is safe at gross above 1100
lbs. I only remember two wing failures. One was an improper repair; one
plane had a secondary gas tank above the main wing and a fuel leak eroded
the foam.

Conclusions: I think the Q2xx main wing is safe up to a gross of 1300
lbs., but anyone flying at gross weights over 1100 lbs should read the
discussion in Quicktalk 28.

I still get angry with people who post "information" like "designed to
30Gs" but don't provide documentation. Then I end up doing the
research. See Title. Monk is my friend. I prefer sleep to research.

Mike Perry


David Posey <dlposey-atlanta@...>
 

Mike Perry wrote:

Recently I produced a set of files designed to help people using Q200s at
gross weight over 1100 lbs. (Now posted on Jon Finley's website as
Q200_POH_supplement.zip) That drew questions on and off list about Marc
Waddelow's analysis of the wing and the allegedly marginal strength of the
main wing. Meanwhile Larry Severson keeps posting a claim that the Q2
canard was designed to 30Gs. Last nite and this AM I re-read everything I
can find on Waddelow's analysis and all the old materials I have on the
Q2xx from QAC and others. Here is my summary:

I did locate one statement supporting the 30G design of the canard, along
with some other interesting information:

Lightweight does not, however, imply low structural margins; at the drawing
board stage, the Q2 rear wing was designed for a positive 12G limit load
and the canard, since it doubles as the main landing gear is required to
withstand over 30G's of positive inflight loads and a 500 ft./min. landing
impact. (Sport Aviation, May 1981, as reprinted by QAC for distribution as
advertising)

The only documentation I have of Marc Waddelow's analysis of the wing is in
Quicktalk # 28, pp 9-10. This is a summary of an exchange of letters
between Marc and Gene Sheehan. To summarize two pages of material, the
more detailed Marc's analysis, the closer he got to Sheehan's numbers. I
have no doubt Marc had a better design, but I think it was only slightly
better. If anyone has more information I am interested. Read the
newsletter, it's too long to reproduce here.

One quote from Sheehan: "As to your [Waddelow's] suggested modifications I
can't see anything wrong with them other than an increase in weight. This
may seem to be a small matter to you but my experience has shown that the
typical homebuilder who doesn't trust the designer and adds a little beef
here and there usually ends up with a very heavy airplane. He also insists
on flying over gross weight. So instead of having a stronger airplane he
may actually have less margin. . . "

Furthermore, Sheehan reported non-destructive testing to 8Gs, and
recommended any modification of the main wing or canard be tested to "at
least 50% above what you wish to use as your limit G loading."

I did not find any documentation of testing to actual limits; that is, no
one built a wing and loaded it until it broke. I think QAC should have,
but they didn't.

We do have other data: there are some amazingly heavy Quickies
flying. Some Q2xxs were built with O235s, full panels, design mods and the
kitchen sink. I have Larry Koutz's listing of flying Qs in the USA,
probably from about year 2000. There are several planes with empty weights
over 825 lbs! Charlie Harris of Littleton Colorado has a Q200 weighing 832
lbs with 1000 hours.

Then we have the Weight and Balance info sent with my kit, showing a gross
of 1300. There is no testing or engineering documentation to support this
that I am aware of.

All this suggests to me the wing structure is safe at gross above 1100
lbs. I only remember two wing failures. One was an improper repair; one
plane had a secondary gas tank above the main wing and a fuel leak eroded
the foam.

Conclusions: I think the Q2xx main wing is safe up to a gross of 1300
lbs., but anyone flying at gross weights over 1100 lbs should read the
discussion in Quicktalk 28.

I still get angry with people who post "information" like "designed to
30Gs" but don't provide documentation. Then I end up doing the
research. See Title. Monk is my friend. I prefer sleep to research.

Mike Perry


Mike , thanks for the work you have done on the documentation for the canard and wing.

David Posey
TriQ200


jon@...
 

Yeah - I agree. Good stuff Mike, thanks for digging it out and writing it up.



Jon

-----Original Message-----
From: David Posey <dlposey-atlanta@...>
Sent: Tuesday, June 3, 2008 1:23pm
To: Q-LIST@...
Subject: Re: [Q-LIST] Load Limits: Confessions of an Obsessive Compulsive Nerd

Mike Perry wrote:

Recently I produced a set of files designed to help people using Q200s at
gross weight over 1100 lbs. (Now posted on Jon Finley's website as
Q200_POH_supplement.zip) That drew questions on and off list about Marc
Waddelow's analysis of the wing and the allegedly marginal strength of
the
main wing. Meanwhile Larry Severson keeps posting a claim that the Q2
canard was designed to 30Gs. Last nite and this AM I re-read everything I
can find on Waddelow's analysis and all the old materials I have on the
Q2xx from QAC and others. Here is my summary:
<snip>


Mike Perry



Mike , thanks for the work you have done on the documentation for the
canard and wing.

David Posey
TriQ200


Mark Alexander <6oclockhigh@...>
 

Mike,


I just want to say thank you for providing some helpful information on Q200
Gross Weight. A few months ago I asked for the Max Gross Weight for a
Tri-Q200 with an LS1 Canard. The conversation went from bad to worst. I
think I was part of the problem because I expected the data to be ready and
available. My rule of thumb is I have to have supporting data to believe
what is being stated. Unless the data is from a owner, builder, operator
who has done the home work to prove their clam in which they are more then
happy to provide. I usually don't believe them. So in having said that I'm
going to break my own rule of thumb.



After the let down with the Website conversation. I went back to some of my
friends who are aeronautical engineers and love to crunch numbers. After
figuring the numbers of Carbon fiber plys, LS1 design by W X L X Cord. The
LS1 wing loading came out to an acceptable safety margin wing loading of
1340 lbs. I wanted to publish the data on the web but my friends asked me
not to because these were not hard facts but based on soft data. We need
more engineer data to build a data predicable simulation. Which really means
IF AND BUT were not calculated in to the math. My friend affectionately
called it; Rutan math.



Because no one knows how fiberglass will react under certain conditions.
It's not repeatable. I mean that we have data to tell when 4130 steel
will start to bend, temperature, shear factors and tensile strength just to
name a few. Metal will shear or show signs that its going to or ductile
overload. Metal is repeatable but fiberglass still has a lot of unknowns.
If I build a metal airplane in my Hangar in the winter (30 *) the metal
still has the same repeatable calculated stress load limits. Same
conditions; Fiberglass not so much. Pound for pound fiberglass is ten times
stronger than metal, if properly manufactured. But you just can't tell when
it's going to break, it just doesn't tell you and there is the dilemma in
calculating fiberglass load limits.



So after all that I guess I'm supporting your findings. I'm still building
on Tri Q200 and I'm still just about done. Just one more thing to finish up
and I'll be flying. BTW I'm listing my Max Gross Weight at 1300 lbs.



Mark

On Tue, Jun 3, 2008 at 12:00 PM, Mike Perry <dmperry1012@...> wrote:

Recently I produced a set of files designed to help people using Q200s
at
gross weight over 1100 lbs. (Now posted on Jon Finley's website as
Q200_POH_supplement.zip) That drew questions on and off list about Marc
Waddelow's analysis of the wing and the allegedly marginal strength of the
main wing. Meanwhile Larry Severson keeps posting a claim that the Q2
canard was designed to 30Gs. Last nite and this AM I re-read everything I
can find on Waddelow's analysis and all the old materials I have on the
Q2xx from QAC and others. Here is my summary:

I did locate one statement supporting the 30G design of the canard, along
with some other interesting information:

Lightweight does not, however, imply low structural margins; at the drawing

board stage, the Q2 rear wing was designed for a positive 12G limit load
and the canard, since it doubles as the main landing gear is required to
withstand over 30G's of positive inflight loads and a 500 ft./min. landing
impact. (Sport Aviation, May 1981, as reprinted by QAC for distribution as
advertising)

The only documentation I have of Marc Waddelow's analysis of the wing is in

Quicktalk # 28, pp 9-10. This is a summary of an exchange of letters
between Marc and Gene Sheehan. To summarize two pages of material, the
more detailed Marc's analysis, the closer he got to Sheehan's numbers. I
have no doubt Marc had a better design, but I think it was only slightly
better. If anyone has more information I am interested. Read the
newsletter, it's too long to reproduce here.

One quote from Sheehan: "As to your [Waddelow's] suggested modifications I
can't see anything wrong with them other than an increase in weight. This
may seem to be a small matter to you but my experience has shown that the
typical homebuilder who doesn't trust the designer and adds a little beef
here and there usually ends up with a very heavy airplane. He also insists
on flying over gross weight. So instead of having a stronger airplane he
may actually have less margin. . . "

Furthermore, Sheehan reported non-destructive testing to 8Gs, and
recommended any modification of the main wing or canard be tested to "at
least 50% above what you wish to use as your limit G loading."

I did not find any documentation of testing to actual limits; that is, no
one built a wing and loaded it until it broke. I think QAC should have,
but they didn't.

We do have other data: there are some amazingly heavy Quickies
flying. Some Q2xxs were built with O235s, full panels, design mods and the
kitchen sink. I have Larry Koutz's listing of flying Qs in the USA,
probably from about year 2000. There are several planes with empty weights
over 825 lbs! Charlie Harris of Littleton Colorado has a Q200 weighing 832
lbs with 1000 hours.

Then we have the Weight and Balance info sent with my kit, showing a gross
of 1300. There is no testing or engineering documentation to support this
that I am aware of.

All this suggests to me the wing structure is safe at gross above 1100
lbs. I only remember two wing failures. One was an improper repair; one
plane had a secondary gas tank above the main wing and a fuel leak eroded
the foam.

Conclusions: I think the Q2xx main wing is safe up to a gross of 1300
lbs., but anyone flying at gross weights over 1100 lbs should read the
discussion in Quicktalk 28.

I still get angry with people who post "information" like "designed to
30Gs" but don't provide documentation. Then I end up doing the
research. See Title. Monk is my friend. I prefer sleep to research.

Mike Perry





John ten
 

Mark,

Unfortunately your posting is riddled with error as well.

You need to get to grips with structural analysis before you post.

This is just plain (and plane) nonsense.

After
figuring the numbers of Carbon fiber plys, LS1 design by W X L X
Cord. The
LS1 wing loading came out to an acceptable safety margin wing loading of
1340 lbs.

LS1 design by W x L x cord ? Huh?

"wing loading of 1340 lbs" is absurd and meaningless. Rutan is known
as one of the most adept composite engineers around, he is well known
for being unbeatable for his speed and accuracy of calculation. The
engobabble you are offering is the opposite.

You are also completely wrong about the behaviour of fiberglass it is
repeatable and well known. The fact that you do not know it should
sound loud warning bells that you need to find out, not make
engineering decisions based on an absence of information.

ten times stronger in what? tension, compression, shear?

If this is the depth of your knowledge and this what you have based
your decision upon to raise the MAUW to 1300 lbs, change your decision
before you kill yourself and others.

John








--- In Q-LIST@..., "Mark Alexander" <6oclockhigh@...> wrote:

Mike,


I just want to say thank you for providing some helpful information
on Q200
Gross Weight. A few months ago I asked for the Max Gross Weight for a
Tri-Q200 with an LS1 Canard. The conversation went from bad to
worst. I
think I was part of the problem because I expected the data to be
ready and
available. My rule of thumb is I have to have supporting data to
believe
what is being stated. Unless the data is from a owner, builder,
operator
who has done the home work to prove their clam in which they are
more then
happy to provide. I usually don't believe them. So in having said
that I'm
going to break my own rule of thumb.



After the let down with the Website conversation. I went back to
some of my
friends who are aeronautical engineers and love to crunch numbers.
After
figuring the numbers of Carbon fiber plys, LS1 design by W X L X
Cord. The
LS1 wing loading came out to an acceptable safety margin wing loading of
1340 lbs. I wanted to publish the data on the web but my friends
asked me
not to because these were not hard facts but based on soft data. We
need
more engineer data to build a data predicable simulation. Which
really means
IF AND BUT were not calculated in to the math. My friend affectionately
called it; Rutan math.



Because no one knows how fiberglass will react under certain conditions.
It's not repeatable. I mean that we have data to tell when 4130 steel
will start to bend, temperature, shear factors and tensile strength
just to
name a few. Metal will shear or show signs that its going to or ductile
overload. Metal is repeatable but fiberglass still has a lot of
unknowns.
If I build a metal airplane in my Hangar in the winter (30 *) the metal
still has the same repeatable calculated stress load limits. Same
conditions; Fiberglass not so much. Pound for pound fiberglass is
ten times
stronger than metal, if properly manufactured. But you just can't
tell when
it's going to break, it just doesn't tell you and there is the
dilemma in
calculating fiberglass load limits.



So after all that I guess I'm supporting your findings. I'm still
building
on Tri Q200 and I'm still just about done. Just one more thing to
finish up
and I'll be flying. BTW I'm listing my Max Gross Weight at 1300 lbs.



Mark

On Tue, Jun 3, 2008 at 12:00 PM, Mike Perry <dmperry1012@...> wrote:

Recently I produced a set of files designed to help people using
Q200s
at
gross weight over 1100 lbs. (Now posted on Jon Finley's website as
Q200_POH_supplement.zip) That drew questions on and off list about
Marc
Waddelow's analysis of the wing and the allegedly marginal
strength of the
main wing. Meanwhile Larry Severson keeps posting a claim that the Q2
canard was designed to 30Gs. Last nite and this AM I re-read
everything I
can find on Waddelow's analysis and all the old materials I have
on the
Q2xx from QAC and others. Here is my summary:

I did locate one statement supporting the 30G design of the
canard, along
with some other interesting information:

Lightweight does not, however, imply low structural margins; at
the drawing

board stage, the Q2 rear wing was designed for a positive 12G
limit load
and the canard, since it doubles as the main landing gear is
required to
withstand over 30G's of positive inflight loads and a 500 ft./min.
landing
impact. (Sport Aviation, May 1981, as reprinted by QAC for
distribution as
advertising)

The only documentation I have of Marc Waddelow's analysis of the
wing is in

Quicktalk # 28, pp 9-10. This is a summary of an exchange of letters
between Marc and Gene Sheehan. To summarize two pages of material, the
more detailed Marc's analysis, the closer he got to Sheehan's
numbers. I
have no doubt Marc had a better design, but I think it was only
slightly
better. If anyone has more information I am interested. Read the
newsletter, it's too long to reproduce here.

One quote from Sheehan: "As to your [Waddelow's] suggested
modifications I
can't see anything wrong with them other than an increase in
weight. This
may seem to be a small matter to you but my experience has shown
that the
typical homebuilder who doesn't trust the designer and adds a
little beef
here and there usually ends up with a very heavy airplane. He also
insists
on flying over gross weight. So instead of having a stronger
airplane he
may actually have less margin. . . "

Furthermore, Sheehan reported non-destructive testing to 8Gs, and
recommended any modification of the main wing or canard be tested
to "at
least 50% above what you wish to use as your limit G loading."

I did not find any documentation of testing to actual limits; that
is, no
one built a wing and loaded it until it broke. I think QAC should
have,
but they didn't.

We do have other data: there are some amazingly heavy Quickies
flying. Some Q2xxs were built with O235s, full panels, design mods
and the
kitchen sink. I have Larry Koutz's listing of flying Qs in the USA,
probably from about year 2000. There are several planes with empty
weights
over 825 lbs! Charlie Harris of Littleton Colorado has a Q200
weighing 832
lbs with 1000 hours.

Then we have the Weight and Balance info sent with my kit, showing
a gross
of 1300. There is no testing or engineering documentation to
support this
that I am aware of.

All this suggests to me the wing structure is safe at gross above 1100
lbs. I only remember two wing failures. One was an improper
repair; one
plane had a secondary gas tank above the main wing and a fuel leak
eroded
the foam.

Conclusions: I think the Q2xx main wing is safe up to a gross of 1300
lbs., but anyone flying at gross weights over 1100 lbs should read the
discussion in Quicktalk 28.

I still get angry with people who post "information" like "designed to
30Gs" but don't provide documentation. Then I end up doing the
research. See Title. Monk is my friend. I prefer sleep to research.

Mike Perry

[Non-text portions of this message have been removed]



[Non-text portions of this message have been removed]


Mike Perry <dmperry1012@...>
 

So, before I spend time answering this E-mail, is it supposed to make more
sense than the last one?

"The numbers for the Q200 and Tri Q200 are out there but no one is giving
up the secret data sheets." Maybe you should take your Haldol, it will
help control your psychosis.

"I guess the questions that I should really ask are: What is the maximum
gross weight that you have ever flown with, what your indicated airspeed at
pitch buck is and what was your sink rate. I think that would give
everyone a real good indication of where the safety limit would
stand." This thread is about load limits. Nothing you wrote here relates
to load limits. If you read the archives and the old newsletters, these
questions are answered.

The simple facts: The engineering expertise behind the Q2xx died July 1982.
The author of the critical analysis of strength of the main wing died Nov.
1986.
The engineering data sheets disappeared with the bankruptcy of QAC.

If you don't think this is serious, you haven't been following the wing
failure thread. Look at the pictures.

"Mike thanks for being even tempered" -- my work taught me to be
patient. Don't presume it is infinite. As far as I'm concerned you have
two strikes. Want to swing at the ball again?

Mike Perry

At 10:59 PM 6/6/2008 -0500, you wrote:
Mike,

LOL! What you read in my E-mail is just what I see in most of the E-mails I
read on the WEB site. I had a lot of fun writing the E-mail. I didn't have
my engineering buddies do any kind of analysis; I think that it was
painfully obvious since you could read through the BS lines. Your words are
kind compared to some. I would think that I would be the biggest asshole in
the world if I had data that would help the Q group and not share it. I
knew John would answer with his normal I'm GOD attitude.

I'm really just frustrated with the lack of engineering data. Burt Rutan is
one of the greatest minds that aviation as ever seen. I remember listening
to him speak in the early 90's in Wichita, KS on the Beechcraft Starship. He
always followed the numbers because they don't lie. The numbers for the
Q200 and Tri Q200 are out there but no one is giving up the secret data
sheets.

The fact of the matter it's, I don't think it's very responsible to state a
maximum gross weight or G loads without supporting it with data. Think
about 30 G's; if the Q weights 1000 lbs doesn't that put you at 30K, leave
the human factor out of the equation and tell me that I can put 29.99K on
the Q wing, Tri Q landing gear and the GU/LS1 canard and it's not going to
break. I would have to see it in person or have a whole lot of engineering
analysis and data to support the claim. I think I understand where Larry is
coming from when he makes the 30G claim. He wants anyone to prove him right
or prove him wrong so at least he has the engineering data. It's a hard way
to approach it with this volatile group!

I think Bruce Crain stated it best on my last question about LS1 wing
loading. The Q has some inherent safety factors built in already. Just how
fat of an ass can you fit between the 16" spaces, we call seats. If your
butts that big you aren't going flying in the Q. Okay look at aft CG, not
much is going behind you and stay clear of the flight controls. Looking at
the Mean Aerodynamic Cord doesn't give you a whole lot of room either way. So
really how much weight can you fit in that small of a space called a cockpit
without tipping the GC off scale?

I guess the questions that I should really ask are: What is the maximum
gross weight that you have ever flown with, what your indicated airspeed at
pitch buck is and what was your sink rate. I think that would give everyone
a real good indication of where the safety limit would stand. I mean
if someone
has already done this and your gross weight is at 1300lbs and you are pitch
bucking at 80mph indicated and your sink rate is 1500 feet per minute, that
right there aint good. I would say that's not where I want to be in my
safety margin. But if you can tell me that at 1100lbs GW, pitch buck is 65
MPH and sink rate is 500 FPM, I'm all over that like a Hobo on a ham
sandwich.

Mike thanks for being even tempered and keeping the BS line in check. John
keep writing those awesome responses to my E-mails, you obviously have argue
issues but you make me LOL. But just to whined you up: shut up and color!
I can't wait for the response. :o))))


On Wed, Jun 4, 2008 at 11:12 AM, Mike Perry <dmperry1012@...> wrote:

John, that's awfully harsh, however:

Mark, your post reads like a non-engineer reporting on what an engineer
said, esp. "the numbers of Carbon fiber plys, LS1 design by W X L X
Cord." I think you are trying to say your engineer friends analyzed the
carbon spar with the overlying fiberglass/foam composite structure and came

to the conclusion it was safe to 1340 lbs. If so, it wasn't clear. (I'm a
non-engineer, I often understand better than I report.)

As far as ". . . no one knows how fiberglass will react under certain
conditions. It's not repeatable." I don't think that is accurate. Two
major things will affect the strength of this type of composite fiberglass
structure: workmanship (orientation of fibers, air bubbles, attachment of
surface to core) and temperature. However, low temperature merely slows
the cure process, it doesn't stop it, and none of our projects go from shop

to airworthy in just a few weeks.

I think Rutan and others have shown that this process is repeatable for the

amateur builder. Get "Moldless Composite Homebuilt Sandwich Aircraft
Construction" by the Rutan Aircraft Factory or any of the other books sold
by Aircraft Spruce that explain the process and strength.

Workmanship is important -- critical perhaps -- and post cure or time fixes

the temperature issue.

Mike Perry


At 10:09 PM 6/3/2008 -0500, you wrote:
Mike,


I just want to say thank you for providing some helpful information on
Q200
Gross Weight. A few months ago I asked for the Max Gross Weight for a
Tri-Q200 with an LS1 Canard. The conversation went from bad to worst. I
think I was part of the problem because I expected the data to be ready
and
available. My rule of thumb is I have to have supporting data to believe
what is being stated. Unless the data is from a owner, builder, operator
who has done the home work to prove their clam in which they are more then
happy to provide. I usually don't believe them. So in having said that I'm
going to break my own rule of thumb.



After the let down with the Website conversation. I went back to some of
my
friends who are aeronautical engineers and love to crunch numbers. After
figuring the numbers of Carbon fiber plys, LS1 design by W X L X Cord. The
LS1 wing loading came out to an acceptable safety margin wing loading of
1340 lbs. I wanted to publish the data on the web but my friends asked me
not to because these were not hard facts but based on soft data. We need
more engineer data to build a data predicable simulation. Which really
means
IF AND BUT were not calculated in to the math. My friend affectionately
called it; Rutan math.



Because no one knows how fiberglass will react under certain conditions.
It's not repeatable. I mean that we have data to tell when 4130 steel
will start to bend, temperature, shear factors and tensile strength just
to
name a few. Metal will shear or show signs that its going to or ductile
overload. Metal is repeatable but fiberglass still has a lot of unknowns.
If I build a metal airplane in my Hangar in the winter (30 *) the metal
still has the same repeatable calculated stress load limits. Same
conditions; Fiberglass not so much. Pound for pound fiberglass is ten
times
stronger than metal, if properly manufactured. But you just can't tell
when
it's going to break, it just doesn't tell you and there is the dilemma in
calculating fiberglass load limits.



So after all that I guess I'm supporting your findings. I'm still building
on Tri Q200 and I'm still just about done. Just one more thing to finish
up
and I'll be flying. BTW I'm listing my Max Gross Weight at 1300 lbs.



Mark