CAD Designer wanted for Jurca Mustang !

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marianmadalin32

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Already started to build a Jurca Mustang Replica. Looking for a volunteer who can draw for free for me parts from PDF files in DWG/DXF in order to continue to cut them on the CNC and assemble them. Many thanks. I had many sponsors who helped for free during this project. If you wish to join, let me know.
 

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Monty

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Already started to build a Jurca Mustang Replica. Looking for a volunteer who can draw for free for me parts from PDF files in DWG/DXF in order to continue to cut them on the CNC and assemble them. Many thanks. I had many sponsors who helped for free during this project. If you wish to join, let me know.
You should at least give them rights to the files or a set of parts. Nobody with any worth is going to do this for free.
 

Riggerrob

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Are you going to make those CAD files available tot others after you complete your project?
Are you going to allow your volunteer CAD draftsman to sell those CAD files?
 

proppastie

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caution....most likely any hand drawn paper was not originally truly lofted smooth because of the inherent errors of hand drawing......weather or not these slight errors are a problem will depend on the amount of error and the type of covering over the frames or the amount of hand finishing the frames the builder expects to do.........fabric covering you probably will not notice...ply covering a straight edge and sand paper will deal with the high/low spots. Metal covering could really show in the skin across the frames.

A properly converted drawing set requires a 3D model of the outer mold line (outside of the aircraft)......Then cuts are made at the location of the inner frames/bulkheads/longerons/ribs/....etc in order to obtain an exact contour.........

to save money or drawing time for a wood aircraft count on some hand finish of the frames at assembly of the aircraft....otherwise you need to make the Cad designer aware of what is needed as regards his output.
 

Riggerrob

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caution....most likely any hand drawn paper was not originally truly lofted smooth because of the inherent errors of hand drawing......weather or not these slight errors are a problem will depend on the amount of error and the type of covering over the frames or the amount of hand finishing the frames the builder expects to do.........fabric covering you probably will not notice...ply covering a straight edge and sand paper will deal with the high/low spots. Metal covering could really show in the skin across the frames.

A properly converted drawing set requires a 3D model of the outer mold line (outside of the aircraft)......Then cuts are made at the location of the inner frames/bulkheads/longerons/ribs/....etc in order to obtain an exact contour.........

to save money or drawing time for a wood aircraft count on some hand finish of the frames at assembly of the aircraft....otherwise you need to make the Cad designer aware of what is needed as regards his output.
On that note ... when you have wooden ribs in a tapered wing ... do you simply cut ribs to the larger/inboard profile, then sand them down to glue precisely to a smooth, plywood skin?
How do you fine-tune curvature on the top of the spar to glue precisely to curved plywood wing skins?
 

proppastie

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On that note ... when you have wooden ribs in a tapered wing ... do you simply cut ribs to the larger/inboard profile, then sand them down to glue precisely to a smooth, plywood skin?
How do you fine-tune curvature on the top of the spar to glue precisely to curved plywood wing skins?
Assuming you are talking about less than perfect parts from hand drawn plans.......Probably best to have the experienced airplane or boat wood working guys answer.......I would guess "whatever works".

In the MM1 the guidance for the ribs was to shift them spanwise so the straight edge in the span wise direction was flat and use the plastic hammer or extra metal to blend......now if curved not straight say a sexy fuselage we see in the plastic aircraft......good question...........
 

marianmadalin32

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Are you going to make those CAD files available tot others after you complete your project?
Are you going to allow your volunteer CAD draftsman to sell those CAD files?
Absolutely not. Any type of commercial activity, selling, buying, renting etc... is forbidden because the copyright for these drawings is owned by mr. Jurca's family, even though he's long gone. These files will be used for educational and nonprofit purposes only!!!
 

BJC

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Who? Give me a link.


BJC
 

wiloows5050

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I spent a lot of time trying to explain jurca drawings to him. His basic knowledge of aircraft construction is limited. If he needs cad drawings he could get a program and do the drawings himself. He would understand the construction of the project much better. I have to many projects going and don’t want my name attached to someone else project, especially having an A&P. Just my two cents.
 

poormansairforce

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I spent a lot of time trying to explain jurca drawings to him. His basic knowledge of aircraft construction is limited. If he needs cad drawings he could get a program and do the drawings himself. He would understand the construction of the project much better. I have to many projects going and don’t want my name attached to someone else project, especially having an A&P. Just my two cents.
The fact that he's asking how much wood he needs in the other thread when the details were right there in the plans all along tells me he should not be building this airplane!
 

Tiger Tim

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On that note ... when you have wooden ribs in a tapered wing ... do you simply cut ribs to the larger/inboard profile, then sand them down to glue precisely to a smooth, plywood skin?
I think I’d just let epoxy fill the gap on assembly unless the wing was very aggressively tapered or the ribs had wide caps for some reason.

To ensure all ribs would work, a friend of mine once made a root and tip rib for a wood skinned wing then put slightly oversize dummy ribs in between made of 1/2” pink foam. Using a half-span sanding block he shaped all the intermediate ribs in place before taking them out to use as templates for the plywood actual ribs. I don’t think those shapes could have been found any faster or more precisely than that.
 

wiloows5050

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You should at least give them rights to the files or a set of parts. Nobody with any worth is going to do this for free.
By not paying for the files he does not own the rights to them. They belong to the person drawing them. There’s were it become a slippery slope. The person doing the drawings can do what he likes with them, however any use of them to build would be in violation of Jurca copyright.
 

Tiger Tim

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The person doing the drawings can do what he likes with them, however any use of them to build would be in violation of Jurca copyright.
I wonder at what point that becomes a problem. If someone made CAD files to CNC cut components for a popular plans built airplane that would be good for all, no? It would of course be a bad idea to totally redraw and sell the entire plan set to replace the originals.
 

pfarber

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caution....most likely any hand drawn paper was not originally truly lofted smooth because of the inherent errors of hand drawing......weather or not these slight errors are a problem will depend on the amount of error and the type of covering over the frames or the amount of hand finishing the frames the builder expects to do.........fabric covering you probably will not notice...ply covering a straight edge and sand paper will deal with the high/low spots. Metal covering could really show in the skin across the frames.

A properly converted drawing set requires a 3D model of the outer mold line (outside of the aircraft)......Then cuts are made at the location of the inner frames/bulkheads/longerons/ribs/....etc in order to obtain an exact contour.........

to save money or drawing time for a wood aircraft count on some hand finish of the frames at assembly of the aircraft....otherwise you need to make the Cad designer aware of what is needed as regards his output.
Unless we are talking 350+ mph a small error is not going to matter.

The plans for the BD-4 explain how to loft a 10in in outline into a full sized 48in rib. Almost all the early kits did this, no major problems unless you have Parkinson or sneeze during the lofting and don't seee thr error.

Also laying out bend lines is still at best a 32nd of an inch accurate.

So not, you dont need a 3d lazer scanned image to make a useable part.
 

Yellowhammer

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By not paying for the files he does not own the rights to them. They belong to the person drawing them. There’s were it become a slippery slope. The person doing the drawings can do what he likes with them, however any use of them to build would be in violation of Jurca copyright.
 

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