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Sepecat Jaguar GR.3A FORWARD FUSELAGE MASTERS COMPLETE...MOSTLY


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  • 2 weeks later...

Here's what's been going on this week. Granted not a lot of visually appealing progress, but important work to true up the model. This is how I'm checking progress and adding fillets and structures. Essentially I am laying out points with horizontal and vertical measurements taken from the drawings. This shows the intake splitter and the measurements for the point of the splitter.

jagmeasure1.png

The measurements are transferred to the model (the little penciled in cross).

jagjig3.jpg

Horizontal measurement method - Long rule, set on a point that matches the end of the pitot, and measurements from there give me distance to vertical planes on the model.

jagjig9.jpg

The height gauge gives me parallel horizontal lines on the model.

Laying out the plastic form you can see it's close but not quite perfect, a little massaging will be necessary. This may look a little extreme but with a model this big these little errors will magnify to larger misalignments later. Plus when I build the rest of parts they may not fit - which kills the whole purpose for all the computer work.

jagjig5.jpg

Even though I have been careful cutting out and "precisely" laying out the cross-section forms, the double checking of the model has revealed a few problems. Here's one that's pretty obvious. I noticed while I was rough sanding that the nose looked a little bent up. All the forms revealed nicely and evenly, but when I checked the profile shape with a little plastic profile you can see the big gap!

jagjig11.jpg

Putting the fuse in the jig you can see that the third cross-section measures out fine.

jagjig2.jpg

But once I got to the tip of the nose you can see it's much higher than it should be. The tip of the height gauge should be even with the top of the tube where the pitot tube fits. I'll cut off the nose, reposition it and then reshape it.

jagjig1.jpg

Filleting has begun as well. The gun port fillet is in progress - you can see the horizontal lines scribed in - they represent panel lines nearest the fillet. Using photos I can judge where the fillet should start and end. This is a feel process really - sand until it looks right.

jagjig7.jpg

Same is going to happen here at the engine area. Angled panel lines have been laid out and I'll start finessing this area.

jagjig8.jpg

When I couldn't take the sanding anymore, I started the intake forms. These will be key to getting area where the intake blends into the fuselage. I pulled cross-sections from the 3d model, two each horizontal and vertical and printed them out. Just likes these, which happen to be forms for the windscreen. The print outs have been glued with Elmer's Glue Stick to 0.040" plastic sheet.

jagjig10.jpg

The sheet came from signs I got at the hardware store. Cheap and more importantly big sizes!

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They are then cut out and fit together. I cut interlocking slots into each part so they slide together, just like those old wood dinosaur skeleton models.

jagjig13.jpg

And last but not least, when I haven't had access to the build, I've been going a little nuts on the 3d seat model.

jagseat3d1.png

jagseat3d2.jpg

That's it for now.

Timmy!

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  • 4 weeks later...

Hey everybody!

Here are some shots of the latest work. The fillets are essentially done and I got the gun ports in place. Next up, spine will be built up and the windscreen forms are to made.

Intakes are attached with foil barriers. The splitter area will need to be shaped with the intakes off - I'll post shots of that when it happens. I needed to get the joints and fillets married up to the separate intake sections first that’s why the temporary attachment of the intakes.

jagfillets1.jpg

jagfillets12.jpg

jagfillets11.jpg

After expending a bunch of brain cells trying to finger out how I was going to get the gun ports done, I think I finally got it. At first blush I thought the interior shape was a square oval, but after finding some good photos I found it was a simple circle. So after contemplating complex drilling methods, I found some styrene tube just the right size. After grinding out the fuse with a Dremel armed with a sanding cylinder, I glued in the tube. Filler applied and some sanding and trimming, I think I got the opening really close.

jagfillets3.jpg

jagfillets13.jpg

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jagfillets10.jpg

While I was at it with the Dremel I got the exhaust area worked out too.

jagfillets2.jpg

Finally, I chopped out the section where the windscreen will fit.

jagfillets7.jpg

More soon

Timmy!

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This is superb, I'm very impressed!

How are you going to make the seat? Seems to me you'd be best off getting it rapid prototyped on an SLA machine after putting all the effort into the CAD model. If you PM me I can give you contact details of a guy very experienced in making rapid prototyes of this nature if you're interested.

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Thanks all for the encouragement!

This is superb, I'm very impressed!

How are you going to make the seat? Seems to me you'd be best off getting it rapid prototyped on an SLA machine after putting all the effort into the CAD model. If you PM me I can give you contact details of a guy very experienced in making rapid prototyes of this nature if you're interested.

Thanks for that I'll be in touch should I go that route. Part of the computer work on the seat is for my own CAD education and it's something to do when I'm away from home.

Today's work. Cut out a bunch of parts and glued them on to the model. The shape is getting more and more recognizable as a jaguar now - it's motivating.

spine1.jpg

spine2.jpg

spine3.jpg

spine4.jpg

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I like the idea of the aluminium skin. Will your master be embedded or can you use it again?

I'm not really sure. It will ultimately depend on how it's cast. As it is it will only serve as the exterior master, an interior plug will be built as well.

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Great work Timmy!

I did seven years in Oman working on RAFO Jaguars, you really seem to be nailing the shapes and contours.

Cheers

Tony

Thanks for that! I really appreciate the feedback from those who got to play with these jets. Having never seen on in person I have to rely on photos and deduction.

Last update for tonight, got one more form skeleton complete. This will become the master for a vacuum formed windscreen - which will be faired into the fuse and become a master for a cast windscreen.

jagwindscreenfrm3.jpg

jagwindscreenfrm2.jpg

jagwindscreenfrm1.jpg

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very nice job so far.

:)

What about the cockpit? Will you create a cockpit tub?

Yes this will be a completely detailed model. Cockpit tub landing gear the works. You are looking at the early phases - detail is down the road a way, but it's coming.

Edited by Timmy!
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