spar caps


Larry Severson
 

In a traditional wing, the skin is NOT load bearing. The spar carries the total load. In many cases, it receives additional strength by the use of spar caps which form an I beam. an I beam is significantly stronger that a straight piece of wood or metal. Other methods include creating a box for greater strength while having lighter weight that an equally strong straight spar.

In the case of foam, the strength (resistance to bending and breaking goes up with the distance between outside layers of glass squared. The primary purpose of the foam is to separate the glass layers. We have to use "stiff" foam because the packing foam tends to compress under pressure, which would decrease the distance between the foam layers. the 2 layers of glass added at a 45 degree angle add torsional stiffness to the wing, but it is the UNI glass that is placed along the wing (canard) span that adds stiffness to the wing (canard). The further apart the UNI (spar caps) are placed the stiffer the lifting surface will be.

So, how stiff (strong) will the result be? We do not have real numbers, but e glass is about 1/4 the stiffness and strength of carbon fiber. AS&S lists a 5 inch wide CF as being 54,000 PSI. This means that a square inch of this material would withstand a stretching force of 54K lbs. Given the 5 inch width, it would take about 17 (16.67) layers in the lamination to achieve the stiffness. On the Q2, there are equal layers of UNI on both the top and bottom surface spread out over the skin surface. The thickness of the airfoil at any point adds to the overall stiffness because the resistance layers of the UNI are forced apart. Think bending moment. The effective strength of the construction is the UNI layer strength at a given point times 1/2 the core (foam) thickness. From this info, anyone can start creating a strength ratio for either of the Q airfoils. However, as has been pointed out, the center section has an added hat section for increased strength. The hat section acts more like a box spar. The UNI "spar caps" are just that. They use the foam to create the effect of a thick, light-weight spar.

From the discussion above, it should be easily understood why the LS1 airfoil REQUIRES the CF spar addition. The airfoil simply is not as thick.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


One Sky Dog
 

Larry ,

When you stray from the plans the responsibility is awesome as the "new"
designer you hold lives in your hand. When you fix a damaged part original
materials must be used to restore the laminate to the design specifications to
restore just the right amount of strength and stiffness. Unless you have a note
from Burt do not redesign these planes you are in way over your head. Your
mumbo jumbo with terms like using stiffness when it should be strength, using
laminate strength claims made in a catalog as "A"basis allowable's to do your
back of the envelope section calculations make me nervous. I have also seen
the quality of your repairs on the flipped Tri-Q and frankly was alarmed. I
cannot sit silent and let you preach design mods to the builders.

I teach advanced composite manufacturing and processing as well as repair
but am not qualified to design composite parts. In one class the students build
a carbon fiber "I" beam from unidirectional pre-impregnated carbon fiber
tape. They also have to calculate the strength and first ply failure and predict
the maximum load the beam will take. We then take the beams to the test 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 the spread
between the predicted and the actual values

For your 30 G claim at 1000 lbs I offer this information. Our "I" beam
design has a +/- 45 degree shear web 0.080 inches thick, caps are 0.130 inches
thick with 19 unidirectional plies for tension/compression. The overall beam is
3" high and 3" wide so we are in the range of a Q canard section somewhere
between the root and tip.

The breaking loads vary from around 5,000 lbs to 9,000 lbs. Quite a variance
for the same laminate built on hard tooling vacuum bagged and autoclave
cured. More sobering is that it is not even close to 30 G's if your working load
is a thousand pounds. You cannot duplicate the quality of these parts in your
garage or hanger and we haven't even talked about adhesively bonded joints.

I do not want to be to harsh and you might be a hot commercial pilot with
what a gazillion hours and a ME degree but are you a practicing composites
structural designer? Playing composite airplane designer gets people killed and
maimed. Follow the dammed plans for your structural parts, exercise your
creativity on tertiary structure and finish.

The above is my humble opinion and I do not wish to offend qualified people.

Regards

One Sky Dog

Charlie Johnson Materials/Process Engineer
Air Force Research Laboratory / Advanced Composites Laboratory

In a message dated 2/13/2008 9:44:12 A.M. Mountain Standard Time,
larry2@... writes:

So, how stiff (strong) will the result be? We do not have real
numbers, but e glass is about 1/4 the stiffness and strength of
carbon fiber. AS&S lists a 5 inch wide CF as being 54,000 PSI. This
means that a square inch of this material would withstand a
stretching force of 54K lbs. Given the 5 inch width, it would take
about 17 (16.67) layers in the lamination to achieve the stiffness.
On the Q2, there are equal layers of UNI on both the top and bottom
surface spread out over the skin surface. The thickness of the
airfoil at any point adds to the overall stiffness because the
resistance layers of the UNI are forced apart. Think bending moment.
The effective strength of the construction is the UNI layer strength
at a given point times 1/2 the core (foam) thickness. From this info,
anyone can start creating a strength ratio for either of the Q
airfoils. However, as has been pointed out, the center section has an
added hat section for increased strength. The hat section acts more
like a box spar. The UNI "spar caps" are just that. They use the foam
to create the effect of a thick, light-weight spar.





**************The year's hottest artists on the red carpet at the Grammy
Awards. Go to AOL Music.
(http://music.aol.com/grammys?NCID=aolcmp00300000002565)


Michael Quinn
 

Larry,
Good clear explanation. The last paragraph you said LS1 requires the spar. I assume you are refering to the traditional landing gear and not the tri-q as the load requirements when the cannard is not doubling as landing gear is much less and can be managed with a design like Mark Wadallow (sp?). Yes?

I did a couple searches (because I know it has been covered - but cannot find the answer) regarding the difference between the blue and orange foam. I also remember reading in the newsletter about a failure with a repair using pour foam rather than the method that the instructions indicate with cutting out and replacing with similar foam.

M.

________________________________
To: Q-LIST@...
From: larry2@...
Date: Wed, 13 Feb 2008 08:43:19 -0800
Subject: [Q-LIST] spar caps


In a traditional wing, the skin is NOT load bearing. The spar carries
the total load. In many cases, it receives additional strength by the
use of spar caps which form an I beam. an I beam is significantly
stronger that a straight piece of wood or metal. Other methods
include creating a box for greater strength while having lighter
weight that an equally strong straight spar.

In the case of foam, the strength (resistance to bending and breaking
goes up with the distance between outside layers of glass squared.
The primary purpose of the foam is to separate the glass layers. We
have to use "stiff" foam because the packing foam tends to compress
under pressure, which would decrease the distance between the foam
layers. the 2 layers of glass added at a 45 degree angle add
torsional stiffness to the wing, but it is the UNI glass that is
placed along the wing (canard) span that adds stiffness to the wing
(canard). The further apart the UNI (spar caps) are placed the
stiffer the lifting surface will be.

So, how stiff (strong) will the result be? We do not have real
numbers, but e glass is about 1/4 the stiffness and strength of
carbon fiber. AS&S lists a 5 inch wide CF as being 54,000 PSI. This
means that a square inch of this material would withstand a
stretching force of 54K lbs. Given the 5 inch width, it would take
about 17 (16.67) layers in the lamination to achieve the stiffness.
On the Q2, there are equal layers of UNI on both the top and bottom
surface spread out over the skin surface. The thickness of the
airfoil at any point adds to the overall stiffness because the
resistance layers of the UNI are forced apart. Think bending moment.
The effective strength of the construction is the UNI layer strength
at a given point times 1/2 the core (foam) thickness. From this info,
anyone can start creating a strength ratio for either of the Q
airfoils. However, as has been pointed out, the center section has an
added hat section for increased strength. The hat section acts more
like a box spar. The UNI "spar caps" are just that. They use the foam
to create the effect of a thick, light-weight spar.

From the discussion above, it should be easily understood why the
LS1 airfoil REQUIRES the CF spar addition. The airfoil simply is
not as thick.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


_________________________________________________________________
Need to know the score, the latest news, or you need your Hotmail®-get your "fix".
http://www.msnmobilefix.com/Default.aspx


Larry Severson
 


The last paragraph you said LS1 requires the spar. I assume you are refering to the traditional landing gear and not the tri-q as the load requirements when the cannard is not doubling as landing gear is much less and can be managed with a design like Mark Wadallow (sp?). Yes?
Absolutely. That is why this discussion started when I said that the Tri was limited by main gear and power, not canard strength. However, the LS1, without the CF spar is weaker than the GU. How much, I can not say for sure. I would expect about 30-40 percent, which would still be adequate for a Tri, assuming that the QAC figure of 30G for the GU canard is accurate. That said, why would you consider the less efficient LS1 canard when you don't have a CF spar available. Even with the VGs, necessary for flight into moisture, your plane will be faster with the GU.


I did a couple searches (because I know it has been covered - but cannot find the answer) regarding the difference between the blue and orange foam.
I have found no info on that either, but I have been told that they are both 2lb foam and hot wireable. The same? I don't know.

I also remember reading in the newsletter about a failure with a repair using pour foam rather than the method that the instructions indicate with cutting out and replacing with similar foam.
Pour foam is not as consistent as the original foam, but it is STIFF, which is the most important factor, as my previous post stated. I see no reason that it can not be used, especially inside the cockpit. On the exposed airfoil, I would not use it due to its poor sanding characteristics.


Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


Peter Harris <peterjfharris@...>
 

Michael

I passed on a copy of the data pages for Styrofoam showing each grade and
the mechanical specifications and I think you will find it in the resources
link on the website.

Peter

_____

From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
Michael Quinn
Sent: Thursday, 14 February 2008 8:09 AM
To: q-list@...
Subject: RE: [Q-LIST] spar caps




Larry,
Good clear explanation. The last paragraph you said LS1 requires the spar. I
assume you are refering to the traditional landing gear and not the tri-q as
the load requirements when the cannard is not doubling as landing gear is
much less and can be managed with a design like Mark Wadallow (sp?). Yes?

I did a couple searches (because I know it has been covered - but cannot
find the answer) regarding the difference between the blue and orange foam.
I also remember reading in the newsletter about a failure with a repair
using pour foam rather than the method that the instructions indicate with
cutting out and replacing with similar foam.

M.

________________________________
To: Q-LIST@yahoogroups. <mailto:Q-LIST%40yahoogroups.com> com
From: larry2@socal. <mailto:larry2%40socal.rr.com> rr.com
Date: Wed, 13 Feb 2008 08:43:19 -0800
Subject: [Q-LIST] spar caps


In a traditional wing, the skin is NOT load bearing. The spar carries
the total load. In many cases, it receives additional strength by the
use of spar caps which form an I beam. an I beam is significantly
stronger that a straight piece of wood or metal. Other methods
include creating a box for greater strength while having lighter
weight that an equally strong straight spar.

In the case of foam, the strength (resistance to bending and breaking
goes up with the distance between outside layers of glass squared.
The primary purpose of the foam is to separate the glass layers. We
have to use "stiff" foam because the packing foam tends to compress
under pressure, which would decrease the distance between the foam
layers. the 2 layers of glass added at a 45 degree angle add
torsional stiffness to the wing, but it is the UNI glass that is
placed along the wing (canard) span that adds stiffness to the wing
(canard). The further apart the UNI (spar caps) are placed the
stiffer the lifting surface will be.

So, how stiff (strong) will the result be? We do not have real
numbers, but e glass is about 1/4 the stiffness and strength of
carbon fiber. AS&S lists a 5 inch wide CF as being 54,000 PSI. This
means that a square inch of this material would withstand a
stretching force of 54K lbs. Given the 5 inch width, it would take
about 17 (16.67) layers in the lamination to achieve the stiffness.
On the Q2, there are equal layers of UNI on both the top and bottom
surface spread out over the skin surface. The thickness of the
airfoil at any point adds to the overall stiffness because the
resistance layers of the UNI are forced apart. Think bending moment.
The effective strength of the construction is the UNI layer strength
at a given point times 1/2 the core (foam) thickness. From this info,
anyone can start creating a strength ratio for either of the Q
airfoils. However, as has been pointed out, the center section has an
added hat section for increased strength. The hat section acts more
like a box spar. The UNI "spar caps" are just that. They use the foam
to create the effect of a thick, light-weight spar.

From the discussion above, it should be easily understood why the
LS1 airfoil REQUIRES the CF spar addition. The airfoil simply is
not as thick.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@socal. <mailto:larry2%40socal.rr.com> rr.com


__________________________________________________________
Need to know the score, the latest news, or you need your HotmailR-get your
"fix".
http://www.msnmobil <http://www.msnmobilefix.com/Default.aspx>
efix.com/Default.aspx


John ten
 

Charlie,

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
behaviour.

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)
wrong.

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
catastrophic.

The headstone manufacture will not care one jot if it was a wing
failure or a canard failure that proved one's undoing...



John




--- In Q-LIST@..., oneskydog@... wrote:

Larry ,

When you stray from the plans the responsibility is awesome as the
"new"
designer you hold lives in your hand. When you fix a damaged part
original
materials must be used to restore the laminate to the design
specifications to
restore just the right amount of strength and stiffness. Unless you
have a note
from Burt do not redesign these planes you are in way over your
head. Your
mumbo jumbo with terms like using stiffness when it should be
strength, using
laminate strength claims made in a catalog as "A"basis allowable's
to do your
back of the envelope section calculations make me nervous. I have
also seen
the quality of your repairs on the flipped Tri-Q and frankly was
alarmed. I
cannot sit silent and let you preach design mods to the builders.

I teach advanced composite manufacturing and processing as well as
repair
but am not qualified to design composite parts. In one class the
students build
a carbon fiber "I" beam from unidirectional pre-impregnated carbon
fiber
tape. They also have to calculate the strength and first ply failure
and predict
the maximum load the beam will take. We then take the beams to the
test 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 the
spread
between the predicted and the actual values

For your 30 G claim at 1000 lbs I offer this information. Our "I" beam
design has a +/- 45 degree shear web 0.080 inches thick, caps are
0.130 inches
thick with 19 unidirectional plies for tension/compression. The
overall beam is
3" high and 3" wide so we are in the range of a Q canard section
somewhere
between the root and tip.

The breaking loads vary from around 5,000 lbs to 9,000 lbs. Quite a
variance
for the same laminate built on hard tooling vacuum bagged and
autoclave
cured. More sobering is that it is not even close to 30 G's if your
working load
is a thousand pounds. You cannot duplicate the quality of these
parts in your
garage or hanger and we haven't even talked about adhesively bonded
joints.

I do not want to be to harsh and you might be a hot commercial
pilot with
what a gazillion hours and a ME degree but are you a practicing
composites
structural designer? Playing composite airplane designer gets
people killed and
maimed. Follow the dammed plans for your structural parts, exercise
your
creativity on tertiary structure and finish.

The above is my humble opinion and I do not wish to offend qualified
people.

Regards

One Sky Dog

Charlie Johnson Materials/Process Engineer
Air Force Research Laboratory / Advanced Composites Laboratory



In a message dated 2/13/2008 9:44:12 A.M. Mountain Standard Time,
larry2@... writes:

So, how stiff (strong) will the result be? We do not have real
numbers, but e glass is about 1/4 the stiffness and strength of
carbon fiber. AS&S lists a 5 inch wide CF as being 54,000 PSI. This
means that a square inch of this material would withstand a
stretching force of 54K lbs. Given the 5 inch width, it would take
about 17 (16.67) layers in the lamination to achieve the stiffness.
On the Q2, there are equal layers of UNI on both the top and bottom
surface spread out over the skin surface. The thickness of the
airfoil at any point adds to the overall stiffness because the
resistance layers of the UNI are forced apart. Think bending moment.
The effective strength of the construction is the UNI layer strength
at a given point times 1/2 the core (foam) thickness. From this info,
anyone can start creating a strength ratio for either of the Q
airfoils. However, as has been pointed out, the center section has an
added hat section for increased strength. The hat section acts more
like a box spar. The UNI "spar caps" are just that. They use the foam
to create the effect of a thick, light-weight spar.





**************The year's hottest artists on the red carpet at the
Grammy
Awards. Go to AOL Music.
(http://music.aol.com/grammys?NCID=aolcmp00300000002565)


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


Allan Farr
 

Im no expert but I read a book by one of the UKs leading fibreglass experts
and from that I understand that overloading fibreglass causes it to be
irreversibly weakened (similar to metal fatigue?). Presumably for a/c that are
regularly overloaded the structural strength safety margin is gradually being
eroded.

Allan F

Q2 not flying

-----Original Message-----
From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
johntenhave
Sent: Thursday, February 14, 2008 4:43 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: spar caps



Charlie,

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
behaviour.

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)
wrong.

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
catastrophic.

The headstone manufacture will not care one jot if it was a wing
failure or a canard failure that proved one's undoing...

John

--- In HYPERLINK "mailto:Q-LIST%40yahoogroups.com"Q-LIST@...,
oneskydog@..-. wrote:

Larry ,

When you stray from the plans the responsibility is awesome as the
"new"
designer you hold lives in your hand. When you fix a damaged part
original
materials must be used to restore the laminate to the design
specifications to
restore just the right amount of strength and stiffness. Unless you
have a note
from Burt do not redesign these planes you are in way over your
head. Your
mumbo jumbo with terms like using stiffness when it should be
strength, using
laminate strength claims made in a catalog as "A"basis allowable's
to do your
back of the envelope section calculations make me nervous. I have
also seen
the quality of your repairs on the flipped Tri-Q and frankly was
alarmed. I
cannot sit silent and let you preach design mods to the builders.

I teach advanced composite manufacturing and processing as well as
repair
but am not qualified to design composite parts. In one class the
students build
a carbon fiber "I" beam from unidirectional pre-impregnated carbon
fiber
tape. They also have to calculate the strength and first ply failure
and predict
the maximum load the beam will take. We then take the beams to the
test 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 the
spread
between the predicted and the actual values

For your 30 G claim at 1000 lbs I offer this information. Our "I" beam
design has a +/- 45 degree shear web 0.080 inches thick, caps are
0.130 inches
thick with 19 unidirectional plies for tension/compression-. The
overall beam is
3" high and 3" wide so we are in the range of a Q canard section
somewhere
between the root and tip.

The breaking loads vary from around 5,000 lbs to 9,000 lbs. Quite a
variance
for the same laminate built on hard tooling vacuum bagged and
autoclave
cured. More sobering is that it is not even close to 30 G's if your
working load
is a thousand pounds. You cannot duplicate the quality of these
parts in your
garage or hanger and we haven't even talked about adhesively bonded
joints.

I do not want to be to harsh and you might be a hot commercial
pilot with
what a gazillion hours and a ME degree but are you a practicing
composites
structural designer? Playing composite airplane designer gets
people killed and
maimed. Follow the dammed plans for your structural parts, exercise
your
creativity on tertiary structure and finish.

The above is my humble opinion and I do not wish to offend qualified
people.

Regards

One Sky Dog

Charlie Johnson Materials/Process Engineer
Air Force Research Laboratory / Advanced Composites Laboratory



In a message dated 2/13/2008 9:44:12 A.M. Mountain Standard Time,
larry2@... writes:

So, how stiff (strong) will the result be? We do not have real
numbers, but e glass is about 1/4 the stiffness and strength of
carbon fiber. AS&S lists a 5 inch wide CF as being 54,000 PSI. This
means that a square inch of this material would withstand a
stretching force of 54K lbs. Given the 5 inch width, it would take
about 17 (16.67) layers in the lamination to achieve the stiffness.
On the Q2, there are equal layers of UNI on both the top and bottom
surface spread out over the skin surface. The thickness of the
airfoil at any point adds to the overall stiffness because the
resistance layers of the UNI are forced apart. Think bending moment.
The effective strength of the construction is the UNI layer strength
at a given point times 1/2 the core (foam) thickness. From this info,
anyone can start creating a strength ratio for either of the Q
airfoils. However, as has been pointed out, the center section has an
added hat section for increased strength. The hat section acts more
like a box spar. The UNI "spar caps" are just that. They use the foam
to create the effect of a thick, light-weight spar.





************-**The year's hottest artists on the red carpet at the
Grammy
Awards. Go to AOL Music.
(HYPERLINK
"http://music.aol.com/grammys?NCID=aolcmp00300000002565"http://music.-aol.com/gr
ammys?-NCID=aolcmp00300-000002565)






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One Sky Dog
 

Allan,

There is a overload response in composites where the bond between the fiber
and the resin gradually breaks down and the laminate gets mushy. I believe
this happened to Larry's main gear legs but I am only guessing as I have not
seen the parts. This is only to cite a recent example and I know Larry had
nothing to do with the gear design and was making a normal landing when the gear
splayed.

This is different than fatigue in metallic isotropic materials and can be
caused by several things. There can be problems with the coatings on the fiber
that are supposed to help the bond. Kind of like a bad primer under a good
paint will make the paint fail early.

It is more likely in the case of fiberglass gear, a structure designed to
absorb bending loads along the fiber axis but plagued by failure from
unaccounted torsion loads. A uni-directional lay-up core with +/- 45 degree plies
wrapped around the outside is a common theme in composite gear leg design. The
core takes the landing bending loads and hopefully you have enough glass on the
outside to take the twisting when the tire skids on the runway. If the
outside layers do not absorb the load then the load is transferred to the resin in
the core putting the resin in tension and compression. The resin is not
supposed to be loaded this way, it's job is to transfer load a short distance
from fiber to fiber thru shear loading. This is the problem and the advantage of
composites it has different strengths and stiff nesses in different
directions. This is where classical closed form equations do not work. You have to
use laminate theory and matrix math and a lot of assumptions to get a part
design. Then you go and break a lot of coupons so you know what the laminate will
take and calibrate the calculations model. Then you build a full up gear
leg and break it to make sure your margin of safety is good. That is the
experiment. Then you build a part you want to stake your life on.

I hope this is helpful and I have not meant to cast aspersions or offend
anyone.

Regards,

One Sky Dog

In a message dated 2/14/2008 12:06:46 A.M. Mountain Standard Time,
afarr@... writes:

I’m no expert but I read a book by one of the UK’s leading fibreglass
experts
and from that I understand that overloading fibreglass causes it to be
irreversibly weakened (similar to metal fatigue?). Presumably for a/c that
are
regularly overloaded the structural strength safety margin is gradually being
eroded.

Allan F

Q2 not flying





**************The year's hottest artists on the red carpet at the Grammy
Awards. Go to AOL Music.
(http://music.aol.com/grammys?NCID=aolcmp00300000002565)


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


Larry Severson
 

Charlie:
Reagan's statement, "Trust, but verify", will always be true when building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2 design that I feel are important. I have not started actual work because I have not been sufficiently sure of certain aspects of the strength requirements. When I am, it will be built from the Q2 hulls that I have in my hanger. The Q2 is a beautiful, efficient plane, but it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


One Sky Dog
 

Larry,

1. Throwing out the 30 G number implies the whole plane will take 30 G's the
problem is there are weak areas some where in the structure that can fail at
substantially lower loads. This is statement unverified and there is no test
data to support it.

2. No dispute.

3. No dispute

4. ?

5. A good repair strives to restore the original strength and stiffness
using original materials because we do not know the designers assumptions. A
stronger repair only drives the loads and failure to the next weak link. The
perfect composite design fails everywhere at the same time above the design
margin of safety. But that never happens in the real world.

6. Cerritos College is a technical school to train people to build parts to
print I was not aware that they taught composite structure design. I am glad
that you took the training and maybe you did not have time to finish the
repairs but they were ugly. Several people commented to me about them and no one
I heard said they were interested in a ride in that plane.

I am not saying that there are not things that could have been done better
than QAC did. Over the years there has been a lot of refinement. My problem is
that people say they are "experimenting" but the test plan for acceptance is
to strap your ass in and hope it holds.

I worked in the rocket motor industry and we experimented all the time. But
before we delivered we had enough testing done that we knew it would work with
a 1.15 margin of safety.

I was flying a commercial product that was tested to +6 -4.5 g that failed
in the air and am lucky to be alive. I do not want someone pulling design out
of the air without testing, telling others that it is ok because "Hey this is
Experimental we can do what we want." and getting people hurt or killed.
"Experimental" is the airworthinesss category not the freedom to ignore the
collective discipline and knowledge of the lessons learned in the certificated
airplane world.

Do not take offence, I am not attacking anyone, I am concerened.

Regards,

Charlie a.k.a. One Sky Dog

In a message dated 2/14/2008 3:58:23 P.M. Mountain Standard Time,
larry2@... writes:




Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
_larry2@... (mailto:larry2@...)







**************The year's hottest artists on the red carpet at the Grammy
Awards. Go to AOL Music.
(http://music.aol.com/grammys?NCID=aolcmp00300000002565)


Doug Humble <hawkidoug@...>
 

FYI - Quickie Newsletter #11 Jan. 1981. Page 4, 1st column. And I quote:

"All this brings us to the next question, is the Q2 aerobatic? Structurally, the aircraft is designed to 12g limit loads...

A good amount, but only 40% of the 30g's being discussed. Lets not be 40% wrong in the future, ok guys?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974

----- Original Message -----
From: larry severson
To: Q-LIST@...
Sent: Thursday, February 14, 2008 4:56 PM
Subject: Re: [Q-LIST] spar caps


Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


Doug Humble <hawkidoug@...>
 

Actually, you were off by 60%.

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974

----- Original Message -----
From: Doug Humble
To: Q-LIST@...
Sent: Thursday, February 14, 2008 11:18 PM
Subject: Re: [Q-LIST] spar caps


FYI - Quickie Newsletter #11 Jan. 1981. Page 4, 1st column. And I quote:

"All this brings us to the next question, is the Q2 aerobatic? Structurally, the aircraft is designed to 12g limit loads...

A good amount, but only 40% of the 30g's being discussed. Lets not be 40% wrong in the future, ok guys?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974
----- Original Message -----
From: larry severson
To: Q-LIST@...
Sent: Thursday, February 14, 2008 4:56 PM
Subject: Re: [Q-LIST] spar caps

Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


Peter Harris <peterjfharris@...>
 

Doug, your reference may bring us closer to the right answer but being from
Missouri I would ask you and Larry who said? and how designed? There may be
some loose statements in the Quickie Newsletter. It would carry some more
weight if we had some more information. I suppose someone did the calcs back
then.



Not that I am planning to do even 4G anytime soon .

Peter



_____

From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
Doug Humble
Sent: Friday, 15 February 2008 3:19 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] spar caps



FYI - Quickie Newsletter #11 Jan. 1981. Page 4, 1st column. And I quote:

"All this brings us to the next question, is the Q2 aerobatic? Structurally,
the aircraft is designed to 12g limit loads...

A good amount, but only 40% of the 30g's being discussed. Lets not be 40%
wrong in the future, ok guys?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974

----- Original Message -----
From: larry severson
To: Q-LIST@yahoogroups. <mailto:Q-LIST%40yahoogroups.com> com
Sent: Thursday, February 14, 2008 4:56 PM
Subject: Re: [Q-LIST] spar caps

Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@socal. <mailto:larry2%40socal.rr.com> rr.com


Steve <sham@...>
 

Doug.
I have had two aerobatic aircraft (Pitts S1 and Super Decathlon) I would not try to attempt any maneuvers in a Q other than a roll. The airframe might withstand the G's but I would not feel comfortable with the control surfaces holding up to the load.

Steve Ham

----- Original Message -----
From: Doug Humble
To: Q-LIST@...
Sent: Friday, February 15, 2008 12:18 AM
Subject: Re: [Q-LIST] spar caps


FYI - Quickie Newsletter #11 Jan. 1981. Page 4, 1st column. And I quote:

"All this brings us to the next question, is the Q2 aerobatic? Structurally, the aircraft is designed to 12g limit loads...

A good amount, but only 40% of the 30g's being discussed. Lets not be 40% wrong in the future, ok guys?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974
----- Original Message -----
From: larry severson
To: Q-LIST@...
Sent: Thursday, February 14, 2008 4:56 PM
Subject: Re: [Q-LIST] spar caps

Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


Sam Hoskins
 

An interesting footnote, is that Tom Jewitt - co-owner of Quacky
Aircraft Company, died as the aircraft that he designed, suffered an
in-flight structural failure.

He was in the race to design an aircraft that could fly around the
world, non-stop, without refueling.

Sam Hoskins
Murphysboro, IL

On Thu, Feb 14, 2008 at 11:18 PM, Doug Humble <hawkidoug@...> wrote:






FYI - Quickie Newsletter #11 Jan. 1981. Page 4, 1st column. And I quote:

"All this brings us to the next question, is the Q2 aerobatic?
Structurally, the aircraft is designed to 12g limit loads...

A good amount, but only 40% of the 30g's being discussed. Lets not be 40%
wrong in the future, ok guys?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974

----- Original Message -----
From: larry severson
To: Q-LIST@...

Sent: Thursday, February 14, 2008 4:56 PM
Subject: Re: [Q-LIST] spar caps

Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...




Larry Severson
 

At 08:52 PM 2/14/2008, you wrote:

Larry,

1. Throwing out the 30 G number implies the whole plane will take 30 G's the
problem is there are weak areas some where in the structure that can fail at
substantially lower loads. This is statement unverified and there is no test
data to support it.
No, it doesn't. Only the GU canard, properly constructed, was claimed to be 30G by QAC. In fact, the main wing was claimed to be 20G. I question that the tail will stay on much above 10G, if that.

5. A good repair strives to restore the original strength and stiffness
using original materials because we do not know the designers assumptions. A
stronger repair only drives the loads and failure to the next weak link. The
perfect composite design fails everywhere at the same time above the design
margin of safety. But that never happens in the real world.
Absolutely true.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


Mike Perry <dmperry1012@...>
 

20G -- 30G -- Where is this documented? WHERE IS THIS DOCUMENTED? Don't
throw out these numbers without documentation.

Mike Perry

At 08:51 AM 2/15/2008 -0800, you wrote:

At 08:52 PM 2/14/2008, you wrote:

Larry,

1. Throwing out the 30 G number implies the whole plane will take 30 G's the
problem is there are weak areas some where in the structure that can fail at
substantially lower loads. This is statement unverified and there is no test
data to support it.
No, it doesn't. Only the GU canard, properly constructed, was claimed
to be 30G by QAC. In fact, the main wing was claimed to be 20G. I
question that the tail will stay on much above 10G, if that.

5. A good repair strives to restore the original strength and stiffness
using original materials because we do not know the designers assumptions. A
stronger repair only drives the loads and failure to the next weak link. The
perfect composite design fails everywhere at the same time above the design
margin of safety. But that never happens in the real world.
Absolutely true.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
<mailto:larry2%40socal.rr.com>larry2@...


Larry Severson
 

At 09:37 AM 2/15/2008, you wrote:

20G -- 30G -- Where is this documented? WHERE IS THIS DOCUMENTED? Don't
throw out these numbers without documentation.

Mike Perry
I will bring back the folder with the info the next time I go to Chino.

In the mean time, I have taken the discussion to the Q-performance list as has been suggested. I realize that many only want to know "what", I prefer "why". I feel safer when I understand what is going on.


Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


Peter Harris <peterjfharris@...>
 

Folks,

According to the POH "Operating Limitations" the maximums listed include

Gross weight 1000lbs

Maneuvering speed 134MPH

Flight load factors +4.4G; -1.76G

We should follow the POH which conforms with the structural design
limitations, otherwise get properly qualifed design input.

Peter



_____

From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
larry severson
Sent: Saturday, 16 February 2008 2:52 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] spar caps



At 08:52 PM 2/14/2008, you wrote:

Larry,

1. Throwing out the 30 G number implies the whole plane will take 30 G's
the
problem is there are weak areas some where in the structure that can fail
at
substantially lower loads. This is statement unverified and there is no
test
data to support it.
No, it doesn't. Only the GU canard, properly constructed, was claimed
to be 30G by QAC. In fact, the main wing was claimed to be 20G. I
question that the tail will stay on much above 10G, if that.

5. A good repair strives to restore the original strength and stiffness
using original materials because we do not know the designers assumptions.
A
stronger repair only drives the loads and failure to the next weak link.
The
perfect composite design fails everywhere at the same time above the design
margin of safety. But that never happens in the real world.
Absolutely true.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@socal. <mailto:larry2%40socal.rr.com> rr.com


Doug Humble <hawkidoug@...>
 

Neither would I Steve. The pilot manual says the limit is 4.4g's and I would want to go there either.

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974

----- Original Message -----
From: Steve
To: Q-LIST@...
Sent: Friday, February 15, 2008 5:41 AM
Subject: Re: [Q-LIST] spar caps



Doug.
I have had two aerobatic aircraft (Pitts S1 and Super Decathlon) I would not try to attempt any maneuvers in a Q other than a roll. The airframe might withstand the G's but I would not feel comfortable with the control surfaces holding up to the load.

Steve Ham

----- Original Message -----
From: Doug Humble
To: Q-LIST@...
Sent: Friday, February 15, 2008 12:18 AM
Subject: Re: [Q-LIST] spar caps

FYI - Quickie Newsletter #11 Jan. 1981. Page 4, 1st column. And I quote:

"All this brings us to the next question, is the Q2 aerobatic? Structurally, the aircraft is designed to 12g limit loads...

A good amount, but only 40% of the 30g's being discussed. Lets not be 40% wrong in the future, ok guys?

Doug "Hawkeye" Humble
A Sign Above www.asignabove.net
Omaha NE
N25974
----- Original Message -----
From: larry severson
To: Q-LIST@...
Sent: Thursday, February 14, 2008 4:56 PM
Subject: Re: [Q-LIST] spar caps

Charlie:
Reagan's statement, "Trust, but verify", will always be true when
building a plane.

But:
1. I did not say that the canard was a 30G design. QAC did.
2. I did say that the design canard spar caps did not go far enough
to adequately protect the tip gear.
3. I stand by my statements that the TriQ is unlikely to place
stresses on the canard equal to those experienced by the dragger.
4. The LS1 canard without the CF spar will be very close in strength
to the main wing. It would NEVER stand up under use with tip gear.
5. The "ugly" repair work that you cite withstood the accident while
original construction parts did not. I have proof in my hanger.
6. Cerritos College is considered the best composite school in the
U.S. I received 18 units of instruction there.

I have already spent over a year working on design changes to the Q2
design that I feel are important. I have not started actual work
because I have not been sufficiently sure of certain aspects of the
strength requirements. When I am, it will be built from the Q2 hulls
that I have in my hanger. The Q2 is a beautiful, efficient plane, but
it has design deficiencies that are not necessary.

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...