The ugly duckling Grumman J2F-6
 

First flight 25. April 1933, with the XJF-1.
First delivery of the JF-1 to the service in US, May 1933.

Produced with these varieties;
XJF-1
JF-1:
JF-2:
JF-3:
J2F-1:
J2F-2:
J2F-2A:
J2F-3:
J2F-4:
J2F-5:
J2F-6 (Columbia):

Some aircraft were designated OA-12 in 1948, for rescue service in Alaska.

Technical Data Grumman J2F-6 Duck:

Wing Span: 39 ft 0 in (11.9 m)

Length: 34 ft 0 in (10.4 m)

Height: 14 ft 6 in (4.4 m)

Wing Area: 409 sq ft (38 sq m)

Weights Empty:
5,480 lbs (2,485 kg)

Maximum T/O:
7,325 lbs (3,322 kg)

Maximum Speed:
190 mph (305 kph)

Cruising Speed:
155 mph (249 km/hr)

Service Ceiling:
25,750 ft (7,848 m)

Normal Range:
875 miles (2,408 km)

Powerplant: One Wright 1820-54 Cyclone rated @ 1,050 hp (783.3 kw)

Armament: One .30 caliber Browning Machine Gun
Two 325lbs (147,4kg) bombs/depth charges

The pic below shows the version I'm going to model. It is not the latest version, but I like it due to its "nostalgic" nose, around the star engine.

Very interesting. Looking forward to seeing your progress.

Just getting started with some sketching
 

Got hand on two drawings. They look ok, so I hope they won't give me much trouble.

I'm thinking of making a nurbs-patch model, as I cannot see how Im supposed to make the model out of primitives alone. I'll try to make some nurbs-surfaces, and attatch them. I hope it works. I'll have to wait to trim the nurbs-surface, else the attatch surface tool will not work.

Look forward to make some decent bump maps, so I don't have to model the bulky metal skin on the wings.

Btw, I read that this was one of the first aircraft that was skinned with metal, and not canvas.

um okay im not a big fan. of non organic stuff. but.. the name alone has drawn me. will be keeping my eye on this. good stuff seth oh beed.

Looks like you plan on putting a lot of work into this project. Can't w8 for an upd8 m8.

A little update on the "duck" NURBS
 

I toyed around with the surface tools and figured out how I could build the fuselage. Here's the plan.

The wings are pretty straight forward. No problem.

The tricky part is to decide on how the cross sections should look like. I do not have any blue prints that deals or help me with the issue of cross sections. I want to keep the cross-sections at a minimum (easier to tweak, and a cleaner result, unless you want to spend time tweaking the small cvs to give the hull a nice continuity).

I have found a way to model the fuselage. I will create curves as cross sections and use a mix of the surface tools.

-Birail tool, several profiles and two rails.
-Fillet blend
-Attatch surface

I guess the trick is to keep the various surface-pathces "attatchable", so that I can weld them together, making a whole and beautiful fuselage.

The big floater will be treated as a seperate object or as a set of objects. No need to attatch it to the main fuselage.

Earlier (some time ago) I used to get annoyed at failing to attatch nurbs surfaces together. But now I have learned to discern the open surfaces from the closed, from the periodic.

The attatch tool will only work when your nurbs surfaces are un-trimmed. So the small trimming will be done later.

Future trim actions;
-trimming for placement of the cockpit
-trimming small holes and such
-possible trimming to shape the tail-rudder (balance-rudder)

At the end the nurbs-surfaces will be converted to polys for easy texturing.

Very interesting undseth. Look forward to see this progressing and hear how you are diung things. I'm trying to get a grip on patch modelling myself right now. Hopefully i'll learn a few things from this model.

Tiny update
 

Well, not much but I'll go work on the cross sections tonight.
This is the status quo.

Trying to make that beautiful fuselage
 

This is not the "skinning process". Only some easy lofting to see how the surface shapes itself after the few curves it is based on.

I have a good feeling about this, although I do not know for sure that my ideas will work.

The second to last image you posted seems a little dark. I can see what's there, but I have to look closely to see it. Is it just my monitor?

Hey undseth - really like how you're going through all the thought processes in planning - you can learn a lot by following along - i've been going through the same process modelling a mclaren with NURBS and trying find out which tools work and when is a good time to trim etc.

I'm taking a break to do the december competition though and something organic. old machines like the ugly duckling here are like beasts with muscles and teeth - looking forward to seeing how it develops

Not much here.
 

Darkware: sorry, the jpg compression from photoshop weren't good.

Ereitz: Good to hear there are others that work with nurbs too. Maybe you can help me with the birail tools.

The pic below shows more clearly how I am supposed to skin the bird. The curves below are just a duplicate for testing, so I'll post the start here and you will all see me complete or lick the asphalt.

Birail tools are wierd
 

I learned much about nurbs today, but the mystery of the birail tool still eludes me.

I have trouble making surfaces that are smooth. Even with smooth curves (rails/profiles) the surface still gets bumpy.

So at the end of the day I have simply lofted a few curves, and... more to come tomorrow.

heheh yeah i hate birail, I can only seem to get biral 2 to work. Great start bud=)

Thanks, I had to get up from bed to figure out the surface-rebuild-tool. It wasnt much helpful for my problem, but it can be handy later on.

Im now settling for lofting the fuselage fore and aft. The tricky middle part is done with the boundry tool. I found out that; by rebuilding the curves, the boundry surface turned out a little prettier. Way from perfect, but it is now tweakable.

The following pic shows the surface to be tweaked. And with newly gained experience, I will be able to attatch the parts together. :)

edit:
I cheated with the 10 span curve. It was supposed to have a hard edge, but I removed it and simply moved the round edge downwards, so it won't be seen when the floater is finished.
edit2:
Correction; the 10 span is actually a 13 span...

I find the BIrail very usefull where the extrude fails - like creating the semi- circular extrusion on my nurbs-truck windscreen

It should have worked fine with extrude but no it did not !


Nir

Woke up late today, but now, im on it.

Next, I'll do the actual modeling and tweaking of the "tricky" part, which will connect the front fuselage to the rear.

The work done below is just to get the cruves right. The skinning can be done a little differently. Connecting a lofted surface with a boundry and then to a lofted surface at the end. But in order to use the boundry, I have to slice all cross-section-curves in half. Ending up with half a fuselage. But it should be easy to attatch the halves together. It did work with the test I performed earlier.

I have now used the boundry tool. The boundry tool is used with three or four curves. In order for easy tweaking, I kept the CV count down.

edit:
oh, the typos... the boundry shape is of course NOT perfect!

Update
 

Well, I remodeled the former surface in a new way. This time I limited the area for the boundry tool and did a rail op. on the part of the fuselage that was going to be pretty smooth.

Using the boundry tool on a limited way, makes the problem of surface irregularities smaller... um well, anyway...

This is the finished part. I wish I knew more about modeling with nurbs patches, but do not have the patience to try to make this part better until I know more about nurbs-patching.

Next I'll have to deal with the front part, which will be the second-hardest part in the project. And soon I'll be onto the fun parts... the details...

Weeeeeeeeh...
 

I finished the nose and although it ain't perfect, I feel it is ok. Besides, the old planes are a bit bumpy aren't they?

Instead of using boundry or rail tool, I made several curves and lofted them forward.

Shazam...
 

The modeling of the tail is well under way.

Almost finished with the tail, I hope you dont mind
 

It is a pleasure to be able to model this and not constantly worry about modeling it the "wrong way".

Tail = 98% done
 

Now off to the floater.

Shaping up very nicely.

It's amazing how much you are learning from this experience.

Keep it up!

Thanks! I feel more comfortable when using the skinning tools, and coming up with decent tweaks, in order to shape a surface the way I want (or a shape that is close enough to my aspirations).

great stuff!
 

yeah, birail, I've also gotten birail 1 to work mostly - i think the reason why it usually fail is that the ends aren't intersecting the rail curves or that the rail curves have a different number of knots... or if the curve is over 90 degrees - apparently it don't like that neither. Hm. I had birail 2 work once as well with really exciting results - it got me to believe that birail 3+ must be a most amazing too capable of creating long, complicated, ever evolving organic mechanical shapes at the drop of a hat. haven't got it to work yet though. Oh and one thing i didn't catch at first was that you choose a profile curve and then have to press enter and then you get the prompt to choose rail 1, then enter and then rail 2... or perhaps it's only me who was so blind as to not get that right off... :)

Have you seen the NURBS modeling tutorial with the suburu? Incredibly helpful if very long and convoluted. Server seems to be down at the moment but it was fine earlier. Link is:

http://www.blissdd.com/

to get the tutorial you will have to register. Worth it though.

The model looks great! More!

Small update
 

That suburu tut still fascinates me. I still have things to learn from it.

I apologize for my lack of updates.
Here is the start of the work on the floater.

I tried to use the birail tools and the boundry tool, but the loft tool seems to work great.

I made the curves and lofted them. The trick is to tweak the cv's of the surface to get that shape I want.

The rear part is ok. The middle part is gonna be ok. The issue now is to tweak the lofted surface to shape the front part.

This looks ok I think
 

I inserted isoparms all over the front part, thus being able to tweak the cv's to shape an edge.

This is the most successful tweaking episode ever! :D:)

Heres the pic
 

Yup...

Just some preparations...
 

Some preparations before I attatch the three surfaces together.

I have inserted isoparms at the edge of the other two parts, so that the attach option doesn't give me a wierd shape.

I guess I inserted too many isoparms here, but I'll go for it.

Another thing; I also inserted isoparms in the other direction (along the model) on the two backmost surfaces, in order to give them the same number of spans as the front surface.

And now they are attatched
 

It worked without problems.

One thing though:
Although the attatch options, make a blend alternative, due to (probably) the closeness of the isoparms, on the surfaces, the blending did not generate that blended surfaces... um..

So, I detatched BOTH surfaces (to be attatched) close to the end, in order to create a gap, which I then fill in with the "attatch surface" with the blend option.

I hope that made sense. :)

Really starting to look good. You are much better with Nurbs than I am. Great start, hope you can finnish this one.
Brian

Small Update
 

Hey thanks Brian!

In the pic below I decided to use the stitch tool to connect the whole floater-fuselage to the two new surfaces under the floater.

But the stitch tool works with a parametrizied set of surfaces, which means that both surfaces to be stitched together, "must/should" have the same number of spans/isoparms.

I had to detatch the first floater-surface I made earlier, in order to stitch the two smaller surfaces to the floater-surface.

These four surfaces had a different number of spans/isoparms, so i had to make them "equal". I could not delete any isoparms, so I inserted isoparms on every surface, so that they eventualy had the same number of spans/isoparms, roughly at the same places.

First rendering of the Duck
 

Just a simple rendering. I could not resist putting it in the thread.

Um here it is
 

Yup

A freeform fillet op
 

After duplicating the outer isoparm to a curve, it was scaled bigger and projected onto the fusalage.

The simple freeform-fillet operation gave me this result.

I know I can modlify the way the fillet is shaped by the freeform-fillet-tool, as the history button is still enabled.

But there is an issue on the surface somewhere, so I'll have to tweak something :)

The fillet surface
 

Hmm. The span count on the two curves are different. The projected curve on the fuselage has a whopping 114 vertices (or so), and the other has only 22.

I am not able to change the span count on the fuselage-curve, but I can move these cv's. The trick is to keep history on and move the cv's on the projected curve (they keep themselves glued" to the fuselage surface) and not try to modify the surface itself (at least not on the outer edges, the inner cv's are modified).

um... so I have tweaked the curve cv's (proj-fuselage-cuve) and some cv's on the fillet surface itself (but only those that aren't on the edge of the surface.

EDIT:
Forget everything above.
The tweaking turned bad :)

However I identified the problem with the former fillet surface.

The problem was that maya had a "hard time" making this fillet surface AND do the tangency thing.

So I tweaked a few cv's on the end of the wing, so that any tangency to these cv's were nice and rounded and not so sharp as was the result in the former try.

This is really coming along nicely.

You know, this would make a great subject for a tutorial. From start to finsh!

:D

Lower wing is finished
 

hmmm I'll have to think aobut it. But no promises.

With the fillet surface ready to attatch to the wind I ran into some issue.

It appeared that the attatch tool did not work. I did eventually figure out how to do this, but do not quite understand what was wrong.

Anyway, the spans running alongside the surfaces were different.
The fillet surface was rebuilt from 26 spans to 22, just like the count on the wing. Stangely, the attatch tool worked this time.

I know the attatch tool did not work with trimmed surfaces, so I undid some easy trims prior to the attatching. I can trim the small things after the attatchment.

I now have a full wing, and I do not intent to attatch it to any object.

Here is the full wing with trim.

Aaah...the wings are now done.
 

It gives me a good feeling to know the hardest parts of this project is done. There are only details left to model.