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... this CAD stuff is fun too. First version of panel test cut is done,  CAD still needs some fine tuning but not bad for a start. -- Robert "TheFrisco" Schmid (408) 805-5450 www.facebook.com/TheFlyingFriscoswww.theflyingfriscos.comLove building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
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Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
toggle quoted message
Show quoted text
On 06/10/2022 06.27, Robert Schmid wrote: ... this CAD stuff is fun too. First version of panel test cut is done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos ( https://www.facebook.com/TheFlyingFriscos )
www.theflyingfriscos.com ( http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann
Avenida de Mariano Vicen 27, Piso 2-I | 42003 Soria | Spain
mail: jo@...
fon : +34 615 81 81 40
"The truth, as always, will be far stranger." [Sir Arthur C. Clarke]
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Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
David J. Gall
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Show quoted text
-----Original Message----- From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann Sent: Thursday, October 6, 2022 3:41 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Maybe tracing is easier but ... Great! CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now. On 06/10/2022 06.27, Robert Schmid wrote: ... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
-- Johannes Weissmann Avenida de Mariano Vicen 27, Piso 2-I | 42003 Soria | Spain mail: jo@... fon : +34 615 81 81 40 "The truth, as always, will be far stranger." [Sir Arthur C. Clarke]
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Oops. I should've addressed this to Johannes, not Robert.
David J. Gall
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Show quoted text
-----Original Message----- From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of David J. Gall Sent: Thursday, October 6, 2022 8:28 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Maybe tracing is easier but ... Robert, If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins. If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio! (If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P) David J. Gall -----Original Message----- From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann Sent: Thursday, October 6, 2022 3:41 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Maybe tracing is easier but ... Great! CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now. On 06/10/2022 06.27, Robert Schmid wrote: ... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
-- Johannes Weissmann Avenida de Mariano Vicen 27, Piso 2-I | 42003 Soria | Spain mail: jo@... fon : +34 615 81 81 40 "The truth, as always, will be far stranger." [Sir Arthur C. Clarke]
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At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
toggle quoted message
Show quoted text
On 06/10/2022 14.28, David J. Gall wrote: Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann
--
Johannes Weissmann
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If anyone is going to burn up the their time “CADing” the Q2/200 to “improve it in some was, I’d suggest that it be scaled up in a similar way that the VariEze was “improved” to become the LongEz. Quite a task to get it right, but there are many folk out there with an appetite and knowledge for that sort of challenge.
Bill Allen
On Thu, 6 Oct 2022 at 14:43, Johannes Weissmann < jo@...> wrote: At the current stage I simply tried to reconstruct the existing shape
based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference
and in addition traced the fuselage profiles from the three-view of the
plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as
little error as possible. The main difficulty is to exactly locate WL0
and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the
curves. Some curvatures from the templates just can't be fitted with
three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as
close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a
physicist) is how much I am getting into the realm of aircraft design or
if the deviations from the original are small enough to not affect the
resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
> Robert,
>
> If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
>
> If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
>
> (If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
>
>
> David J. Gall
>
> -----Original Message-----
> From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
> Sent: Thursday, October 6, 2022 3:41 AM
> To: main@Q-List.groups.io
> Subject: Re: [Q-List] Maybe tracing is easier but ...
>
> Great!
>
> CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
>
> On 06/10/2022 06.27, Robert Schmid wrote:
>> ... this CAD stuff is fun too. First version of panel test cut is
>> done,
>>
>> CAD still needs some fine tuning but not bad for a start.
>> --
>> Robert "TheFrisco" Schmid
>> (408) 805-5450
>>
>> www.facebook.com/TheFlyingFriscos (
>> https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
>> http://www.theflyingfriscos.com )
>>
>> Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
>>
>>
>>
>>
>>
>>
>
> --
> Johannes Weissmann
>
>
>
>
>
>
>
>
>
>
>
--
Johannes Weissmann
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Don't forget to include the mounting brackets and such behind the panel. My first two cardboard panel cutouts didn't take into account the hinges for my forward canopy. But that was ~35 years ago - we're all smarter now, right?
Paul Q-200 N17PF
On Wed, Oct 5, 2022, 23:27 Robert Schmid < robert@...> wrote: ... this CAD stuff is fun too. First version of panel test cut is done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
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Jay Scheevel
toggle quoted message
Show quoted text
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote:
At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.Here is what I am not sure of:What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.// JohannesOn 06/10/2022 14.28, David J. Gall wrote:Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann
-- Johannes Weissmann
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Yeah, I will have to consider how to mount, strengthen and support the panel in there middle because I won't need the space and depth stream/gyro gauges had.
Also, I'll probably scissor hinge my canopy on the side, copied from Jim P.
Thanks for the reminder,
Robert
Don't forget to include the mounting brackets and such behind the panel. My first two cardboard panel cutouts didn't take into account the hinges for my forward canopy. But that was ~35 years ago - we're all smarter now, right?
Paul Q-200 N17PF
On Wed, Oct 5, 2022, 23:27 Robert Schmid < robert@...> wrote: ... this CAD stuff is fun too. First version of panel test cut is done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos
www.theflyingfriscos.com
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
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Robert------------ Just noticed your elevator connection to the stick. How are you connecting the elevator bellcranks?
Show us some pictures and we may be able give you some options.--------- Chris
--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
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Thanks Jay,
I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall.
The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model.
I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help.
Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface.
Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page 17-20 are not.
// Johannes
toggle quoted message
Show quoted text
On 06/10/2022 15.23, Jay Scheevel wrote: Johannes. For WL reference sketches please see pages 17-20 of the following linked document http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheevel_Construction.pdf
Cheers,
Jay
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote:
At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann --
Johannes Weissmann
--
Johannes Weissmann
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Johannes,
Page 8-2 shows the 2.9" dimension on the firewall. Page 8-4 repeats the image with the "Shell Split Line" explicitly labeled. The firewall template on Appendix Sheet 3 shows WL 12.1 explicitly as the line splitting between the fuselage upper and lower shells. WL 12.1 is 2.9" below WL 15....
David J. Gall
toggle quoted message
Show quoted text
-----Original Message----- From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann Sent: Thursday, October 6, 2022 10:19 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Maybe tracing is easier but ... Thanks Jay, I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall. The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model. I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help. Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface. Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page 17-20 are not. // Johannes On 06/10/2022 15.23, Jay Scheevel wrote: Johannes. For WL reference sketches please see pages 17-20 of the
following linked document
http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheevel
_Construction.pdf
Cheers,
Jay
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote:
At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for
the world.... ;P) David J. Gall -----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of
Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos )
www.theflyingfriscos.com ( http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann --
Johannes Weissmann
-- Johannes Weissmann
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Johannes,
Try to stick to degree-two curves (conic sections) as much as possible, and fit them piecewise with tangent continuity at the joins. Use the control point "weight" on the middle control point to adjust the amount of curve for each degree-two conic curve. This is how the P-51 was designed and (except for the possible occasional use of a French Curve) is likely how the Q2 molded fuselage was formed. (Also much TLAR freehand drawing....)
David J. Gall
toggle quoted message
Show quoted text
-----Original Message----- From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann Sent: Thursday, October 6, 2022 8:43 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Maybe tracing is easier but ... At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates. Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling. Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references. Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines. Here is what I am not sure of: What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms. What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs. // Johannes On 06/10/2022 14.28, David J. Gall wrote: Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for
the world.... ;P)
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of
Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com
( http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann
-- Johannes Weissmann
|
|
|
Yes, thanks so much. I totally forgot about those lines on the template.
When I traced the firewall, I was not sure if they really show the fuselage split line. At least in the template I have, they are not labelled; although it makes sense.
Edit: In Appendix Sheet 1, for bulkhead the lines are actually labelled as "Fuselage Split Line, approximate". I think that's enough to properly constraint the sketches.
Thanks, it was all along in front of my nose...
// Johannes
toggle quoted message
Show quoted text
On 06/10/2022 16.32, David J. Gall wrote: Johannes,
Page 8-2 shows the 2.9" dimension on the firewall. Page 8-4 repeats the image with the "Shell Split Line" explicitly labeled. The firewall template on Appendix Sheet 3 shows WL 12.1 explicitly as the line splitting between the fuselage upper and lower shells. WL 12.1 is 2.9" below WL 15....
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 10:19 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Thanks Jay,
I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall.
The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model.
I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help.
Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface.
Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page
17-20 are not.
// Johannes
On 06/10/2022 15.23, Jay Scheevel wrote:
Johannes. For WL reference sketches please see pages 17-20 of the
following linked document
http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheevel
_Construction.pdf
Cheers,
Jay
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote:
At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for
the world.... ;P) David J. Gall -----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of
Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos )
www.theflyingfriscos.com ( http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann --
Johannes Weissmann
--
Johannes Weissmann
|
|
|
Johannes, Please note that all the side view drawings of the Q2/200 throughout the plans are not accurate representations of the silhouette of the actual airplane. The lower silhouette line of the side view of actual molded tail cone parts is more gently curved and the curve extends further aft than FS 120 before becoming a straight line. Your earlier CAD image looks like it has a glandular ailment in the midsection (below the main wing and behind the seatback) and I suspect it is because of over-reliance on the QAC side-view drawings. Compare:  
You might do well to try to get someone to take a multitude of pictures of their airplane and run them through some photogrammetry software to develop actual lines instead of relying on the QAC pencil sketches. Also note that because of draft angle requirements for release of molded parts from molds, the sketch on page 8-2 of the plans can be a huge clue as to where the vertical tangent planes of the fuselage shells need to be located, and this translates directly to the bulkheads. For example, the vertical tangency point of the firewall is located explicitly on WL 12.1 where the upper and lower shells meet. Reverse engineering is HARD!!! Again, it’s likely better to try to duplicate (in CAD) the physical methods used to make the actual molded parts than to rely on the sketches that were included in the plans. I don’t believe there was ever any real attempt to loft this airplane on paper and, if there was, it was held as a corporate secret. The “plans” for the fuselage are just representative sketches to aid in assembly. David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 10:19 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ... Thanks Jay, I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall. The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model. I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help. Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface. Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page 17-20 are not. // Johannes On 06/10/2022 15.23, Jay Scheevel wrote: > Johannes. For WL reference sketches please see pages 17-20 of the > following linked document > http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheevel > _Construction.pdf > > Cheers, > Jay >> On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote: >> >> At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates. >> >> Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling. >> >> Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references. >> >> Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines. >> >> >> Here is what I am not sure of: >> >> What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms. >> >> What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs. >> >> >> // Johannes >> >> >>> On 06/10/2022 14.28, David J. Gall wrote: >>> Robert, >>> If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins. >>> If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio! >>> (If you're surface modeling in SolidWorks, well, there's no hope for >>> the world.... ;P) David J. Gall -----Original Message----- >>> From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of >>> Johannes Weissmann >>> Sent: Thursday, October 6, 2022 3:41 AM >>> To: main@Q-List.groups.io >>> Subject: Re: [Q-List] Maybe tracing is easier but ... >>> Great! >>> CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now. >>>> On 06/10/2022 06.27, Robert Schmid wrote: >>>> ... this CAD stuff is fun too. First version of panel test cut is >>>> done, >>>> >>>> CAD still needs some fine tuning but not bad for a start. >>>> -- >>>> Robert "TheFrisco" Schmid >>>> (408) 805-5450 >>>> >>>> www.facebook.com/TheFlyingFriscos ( >>>> https://www.facebook.com/TheFlyingFriscos ) >>>> www.theflyingfriscos.com ( http://www.theflyingfriscos.com ) >>>> >>>> Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane. >>>> >>>> >>>> >>>> >>>> >>>> >>> -- >>> Johannes Weissmann >> >> -- >> >> Johannes Weissmann >> >> >> >> >> >> > > > > > > -- Johannes Weissmann
|
|
|
Johannes,
My apology! When I referenced Appendix Sheet 3 I was looking at the Q-200 Engine Installation plans Appendix Sheet 3. The Q2 plans appendix sheets have no such annotations. I've attached the Q-200 appendix sheets here in case you don't have them.
David J. Gall
toggle quoted message
Show quoted text
-----Original Message----- From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann Sent: Thursday, October 6, 2022 10:51 AM To: main@Q-List.groups.io Subject: Re: [Q-List] Maybe tracing is easier but ... Yes, thanks so much. I totally forgot about those lines on the template. When I traced the firewall, I was not sure if they really show the fuselage split line. At least in the template I have, they are not labelled; although it makes sense. Edit: In Appendix Sheet 1, for bulkhead the lines are actually labelled as "Fuselage Split Line, approximate". I think that's enough to properly constraint the sketches. Thanks, it was all along in front of my nose... // Johannes On 06/10/2022 16.32, David J. Gall wrote: Johannes,
Page 8-2 shows the 2.9" dimension on the firewall. Page 8-4 repeats the image with the "Shell Split Line" explicitly labeled. The firewall template on Appendix Sheet 3 shows WL 12.1 explicitly as the line splitting between the fuselage upper and lower shells. WL 12.1 is 2.9" below WL 15....
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of
Johannes Weissmann
Sent: Thursday, October 6, 2022 10:19 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Thanks Jay,
I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall.
The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model.
I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help.
Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface.
Side note: the drawings seem to be distorted. I traced and scaled
these drawing as well as the three view, compared and measured them. I
believe the three-view profiles are properly scaled while the drawings
on page
17-20 are not.
// Johannes
On 06/10/2022 15.23, Jay Scheevel wrote:
Johannes. For WL reference sketches please see pages 17-20 of the
following linked document
http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheeve
l
_Construction.pdf
Cheers,
Jay
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote:
At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope
for the world.... ;P) David J. Gall -----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of
Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos )
www.theflyingfriscos.com ( http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann --
Johannes Weissmann
-- Johannes Weissmann
|
|
|
Jay Scheevel
Check me on this Johannes, but I am pretty sure that the top of the jigging table is WL0. I think that’s correct.
Cheers,
Jay
toggle quoted message
Show quoted text
On Oct 6, 2022, at 8:18 AM, Johannes Weissmann <jo@...> wrote:
Thanks Jay,
I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall.
The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model.
I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help.
Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface.
Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page 17-20 are not.
// Johannes
On 06/10/2022 15.23, Jay Scheevel wrote:
Johannes. For WL reference sketches please see pages 17-20 of the following linked document http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheevel_Construction.pdf
Cheers,
Jay
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote: At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann --
Johannes Weissmann
--
Johannes Weissmann
|
|
|
Currently, to make things match the table top would be at WL -2.8. I will update with the reference dimensions from the firewall David sent.
toggle quoted message
Show quoted text
On 06/10/2022 17.49, Jay Scheevel wrote: Check me on this Johannes, but I am pretty sure that the top of the jigging table is WL0. I think that’s correct.
Cheers,
Jay
On Oct 6, 2022, at 8:18 AM, Johannes Weissmann <jo@...> wrote:
Thanks Jay,
I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall.
The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model.
I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help.
Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface.
Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page 17-20 are not.
// Johannes
On 06/10/2022 15.23, Jay Scheevel wrote:
Johannes. For WL reference sketches please see pages 17-20 of the following linked document http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheevel_Construction.pdf
Cheers,
Jay
On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote: At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates.
Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling.
Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references.
Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines.
Here is what I am not sure of:
What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms.
What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs.
// Johannes
On 06/10/2022 14.28, David J. Gall wrote:
Robert,
If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins.
If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio!
(If you're surface modeling in SolidWorks, well, there's no hope for the world.... ;P)
David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 3:41 AM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ...
Great!
CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now.
On 06/10/2022 06.27, Robert Schmid wrote:
... this CAD stuff is fun too. First version of panel test cut is
done,
CAD still needs some fine tuning but not bad for a start.
--
Robert "TheFrisco" Schmid
(408) 805-5450
www.facebook.com/TheFlyingFriscos (
https://www.facebook.com/TheFlyingFriscos ) www.theflyingfriscos.com (
http://www.theflyingfriscos.com )
Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane.
--
Johannes Weissmann --
Johannes Weissmann
--
Johannes Weissmann
--
Johannes Weissmann
|
|
|
Johannes, Here's a start on a Q-200 firewall using the method of conics that I suggested. (Rhino CAD file attached.) 
As you can see, either the original drawing or the scan is not symmetrical, particularly on the lower half of the firewall. Also, I had to scale the entire drawing in the vertical direction slightly to make the measurements match the notations. There is no assurance that a part built from this drawing would fit the molded shells. David J. Gall
-----Original Message-----
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Johannes Weissmann
Sent: Thursday, October 6, 2022 12:07 PM
To: main@Q-List.groups.io
Subject: Re: [Q-List] Maybe tracing is easier but ... Currently, to make things match the table top would be at WL -2.8. I will update with the reference dimensions from the firewall David sent. On 06/10/2022 17.49, Jay Scheevel wrote: > Check me on this Johannes, but I am pretty sure that the top of the jigging table is WL0. I think that’s correct. > > Cheers, > Jay >> On Oct 6, 2022, at 8:18 AM, Johannes Weissmann <jo@...> wrote: >> >> Thanks Jay, >> >> I have used these drawings as the reference. What is lacking, or maybe I am not seeing it, is how to properly constraint WL15. In particular, I never found a way to properly define the vertical position of WL15 on the bulkheads or the firewall. >> >> The way I set up the constraints is that I took the fuselage end, at which the 1" vertical distance from WL15 is given as a dimension. I then rotated the sketch such that the firewall is vertical. This is how WL15 is approximated in my model. >> >> I don't have any reference to the position of the fuselage split line at the firewall, so the 2.9" dimension at the firewall doesn't help. >> >> Once that was fixed, I adjusted the fuselage skid "by hand" to match the fuselage profile to get the WL of the table surface. >> >> Side note: the drawings seem to be distorted. I traced and scaled these drawing as well as the three view, compared and measured them. I believe the three-view profiles are properly scaled while the drawings on page 17-20 are not. >> >> // Johannes >> >>> On 06/10/2022 15.23, Jay Scheevel wrote: >>> Johannes. For WL reference sketches please see pages 17-20 of the >>> following linked document >>> http://n8wq.scheevel.com/documents/Q2_Q200_Plans_Abridged_for_Scheev >>> el_Construction.pdf >>> Cheers, >>> Jay >>>>> On Oct 6, 2022, at 6:43 AM, Johannes Weissmann <jo@...> wrote: >>>> >>>> At the current stage I simply tried to reconstruct the existing shape based on the available plans and templates. >>>> >>>> Basically, I used the fuselage jig and bulkhead templates as reference and in addition traced the fuselage profiles from the three-view of the plans. The templates are to scale, the three-view needed some scaling. >>>> >>>> Based on that, I tried to make the templates and bulkheads match with as little error as possible. The main difficulty is to exactly locate WL0 and WL15 as I could not find any references. >>>> >>>> Currently, there is no limit on the degree I used to generate the curves. Some curvatures from the templates just can't be fitted with three-degree splines. >>>> >>>> >>>> Here is what I am not sure of: >>>> >>>> What I would *like to do* now, is to construct a design that matches as close as possible with simple mathematical forms. >>>> >>>> What I don't know because I am not an aeronautical engineer (I am a physicist) is how much I am getting into the realm of aircraft design or if the deviations from the original are small enough to not affect the resulting aircraft performance and specs. >>>> >>>> >>>> // Johannes >>>> >>>> >>>>> On 06/10/2022 14.28, David J. Gall wrote: >>>>> Robert, >>>>> If your intent is to duplicate the existing QAC shape I would caution you that, although "CAD is fun" it can also lead you astray. The state-of-the-art in the early 1980s was compass and protractor and a wooden batten as a spline; the CAD equivalents are *not* degree-three curvature-continuous NURBS curves and surfaces. Stick to degree-two conics or arcs of circles joined tangent-continuous for cross sections and nothing more than degree-three single-span curves in the longitudinal direction. If more than one degree-three span is needed longitudinally, join degree-three splines at their ends using nothing more than tangent-continuous joins. >>>>> If, on the other hand, your intent is to make it "better," first, define "better," then go for it! Coolio! >>>>> (If you're surface modeling in SolidWorks, well, there's no hope >>>>> for the world.... ;P) David J. Gall -----Original Message----- >>>>> From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of >>>>> Johannes Weissmann >>>>> Sent: Thursday, October 6, 2022 3:41 AM >>>>> To: main@Q-List.groups.io >>>>> Subject: Re: [Q-List] Maybe tracing is easier but ... >>>>> Great! >>>>> CAD is indeed a lot of fun. I finished the first surface model of the Q2 fuselage yesterday. Not perfect yet, but at least it is spanning the whole fuselage now. >>>>>> On 06/10/2022 06.27, Robert Schmid wrote: >>>>>> ... this CAD stuff is fun too. First version of panel test cut is >>>>>> done, >>>>>> >>>>>> CAD still needs some fine tuning but not bad for a start. >>>>>> -- >>>>>> Robert "TheFrisco" Schmid >>>>>> (408) 805-5450 >>>>>> >>>>>> www.facebook.com/TheFlyingFriscos ( >>>>>> https://www.facebook.com/TheFlyingFriscos ) >>>>>> www.theflyingfriscos.com ( http://www.theflyingfriscos.com ) >>>>>> >>>>>> Love building planes almost as much as flying. Latest completed build is "Loki", a Chinook Plus 2 bush plane. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> -- >>>>> Johannes Weissmann >>>> >>>> -- >>>> >>>> Johannes Weissmann >>>> >>>> >>>> >>>> >>>> >>>> >> >> -- >> >> Johannes Weissmann >> >> >> >> >> >> > > > > > > -- Johannes Weissmann
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Danged email down sampled my picture so it’s all fuzzy looking. Here’s a better image:
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