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checksix

1/32 scale T-38C Talon from scratch

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Excellent! I used the same technique to build my Viking, but your method of burying the fuselage into plaster makes it more precise - great idea. I will keep this in mind for my next attempt. Can't wait to see more progress!

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This is going to be great. I have thought about doing this with a CL-215 from 1/72nd to 1/32nd, but not how you've done it with the plaster, that's great. I now have a 1/33rd card model CL-215 though... that I've cut out and making up the bulkheads etc.. very much like Pete's 1/24th Tigercat. 

 

Going to enjoy watching this come together. 

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Fuselage

 

Next it was time to print out all the paper cutting templates:

 

http://revenanteagle.org/checksix/lsp_1/cross_sections_page_0.pdf

http://revenanteagle.org/checksix/lsp_1/cross_sections_page_1.pdf

http://revenanteagle.org/checksix/lsp_1/cross_sections_page_2.pdf

http://revenanteagle.org/checksix/lsp_1/cross_sections_page_3.pdf

http://revenanteagle.org/checksix/lsp_1/cross_sections_page_4.pdf

http://revenanteagle.org/checksix/lsp_1/cross_sections_page_5.pdf

 

I sprayed the paper and wood surfaces with 3M 77 contact adhesive (rubber cement), allowed them to tack dry, and applied the paper to the wood sheets. This makes a secure bond, but the paper can easily be peeled off later after applying heat with a hair dryer or hot air gun.

 

A jig saw was used to cut out each slab:

 

slab_on_jigsaw.jpg

 

Then the pieces were sanded to the line with a table top belt sander:

 

slab_on_sander.jpg

 

The sander was a cheapo $80 unit but worked great. It's quick, accurate, produces clean square edges, and turns an otherwise tedious hand operation into a fun job.

 

The moment of truth arrived. After all this image processing, scaling, cutting, and sanding, would the wood cross sections match the plans? Yup:

 

slabs_on_plan.jpg

 

After this successful test fit, the slabs were glued together using slow cure laminating epoxy (1 hour pot life, overnight cure) to ensure plenty of time was available for careful positioning. Then a surface coat of epoxy was applied to stabilize and waterproof the wood grain.

 

Milliput was used to fill in the "staircase" and provide the initial base for subsequent smoothing. I found the best (albeit messy) way to apply Milliput is to push it around in small dabs using wet fingers:

 

slabs_glued_and_filled.jpg

 

Next, the fuselage halves were faced internally with .010" styrene sheet to give a clean separation plane and then mated together without glue, using internal metal dowel pins to maintain alignment and a single screw to apply pressure:

 

sides_married.jpg

 

The plan was to fully shape and smooth the fuselage as a single piece, but allow the possibility to later cleanly pop it back apart into half-sections for use as vacuum form patterns.

 

Multiple rounds of priming, filling, and sanding ensued:

 

filling.jpg

 

The only tool used was sandpaper strip backed with a 6" x 1/2" flexible steel ruler. 100 grit (dry) was used sparingly to knock off the initial roughness, followed by wet sanding with 320, 400, and 600 grits as the shape was refined with successive layers of primer and filler. Perhaps 10 or 12 layers were required.. A simple hot box (cardboard box with small space heater on one end) was used to speed things up, but even so, each layer required 2-3 hours to cure before the next round of sanding could begin.

 

Eventually, something resembling a Talon emerged:

 

fuselage_filled_and_smoothed.jpg

 

More to follow...

Edited by checksix

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Well, first off welcome to the LSP group. Secondly, you have the patience of a saint to cut those 62 slabs out.

As a woodworker / cabinetmaker, I can appreciate your clever sliding jig, well done. That alone is a project to itself.

Like the others have already stated, you'll fit right in here. You'll probably even teach a few of us on here a thing or two. Hats off to you sir for tackling this en devour and good luck with the project. I'll be following along.

 

Steve

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Canopy

 

I'd never vacuum formed anything before, so this was new territory for me. A little research seemed to indicate that PETG is the preferred material for thermoforming clear plastic canopies so I ordered some 6"x12"x.020" sheets from ebay.

 

Now I had to decide how to proceed: I could either form the canopy directly on the fuselage, or I could cut out the canopy portion of the fuselage and use that. I elected to form the canopy directly on the fuselage so that the canopy edges would (hopefully) blend out smoothly to match the contours of the fuse.

 

Building a vacuum jig was simple: a rectangle of MDF with a hole cut in the center connected to my shop vac provides the base. A few layers of window screening provide a vacuum distribution system and some 1"x1" rubber window insulation provides a seat on which to lay the carrier frame for the PETG sheet, which is held in place with some metal clips.

 

The carrier was placed on metal blocks over a cookie sheet in our kitchen oven at 320F for about 2-3/4 minutes, at which point the PETG sheet started to sag. The vacuum cleaner was switched on and, using gloves, the carrier was quickly removed from the oven and placed on the jig:

 

vac_forming_canopy.jpg

 

The first attempt was a bust because I misaligned the carrier, but two more "pulls" were successful. I stopped after the third pull because the MDF carrier board was starting to deform from the heat.

 

The final step was to mark the plastic for trimming. I used frisket paper to trace out the canopy outlines from the photo and transfer them to the fuselage, then put the canopy in place and applied tape over the lines:

 

canopy_marked_for_trimming.jpg

 

 

More to come...

Edited by checksix

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I like your vacuform design and will be modifying my DIY box and frame like this.  Metal clips seem so much easier than the bolts and wingnuts I've been using. I too love sandpaper on rulers. Just a little flex is nice.   

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Cockpit

 

Now, another design decision: should I go the vacuum forming route and split my nice fuselage into halves for use as patterns, or should I keep the fuselage intact and continue as-is with a solid wood model?

 

The scale skin thickness provided by vac formed styrene would allow much more detailing in the cockpit, wheel wells, and engine inlets, as well as scribed panel lines etc. But I was not confident in my ability to successfully vac form large parts with deep draws and significant undercuts.

 

A solid wood fuse would be easier and quicker to finish. But it would be difficult to build out a nice cockpit and other details in solid wood.

 

I finally decided to go with a solid fuse, treating this build as a "practice" run, and seeing how far I could take it without detouring off into a side project of building a vac forming machine and learning how to use it.

 

I took a big gulp, cut off the canopy, and started hogging out the cockpit with a drill press and various dremel tools:

 

cockpit_excavation.jpg

 

After much grinding:

 

cockpit_hollowed_out.jpg

 

More to come...

Edited by checksix

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Inlets and exhausts

 

Engine inlets and splitters were carved from basswood stock using sanding blocks, dremel tools, and files, followed by the usual priming, filling, and sanding:

 

inlets.jpg

 

After gluing and bolting to the fuselage, the inlets were blended in with filler:

 

inlets_installed_rough.jpg

 

After more sanding, priming, and filling:

 

inlets_installed_smooth.jpg

 

Exhaust cans were next:

 

exhaust_cans.jpg

 

Each can was formed by mounting a basswood cube on a bolt and spinning the assembly in a drill press while shaping wiith a dremel grinder and sanding block. For now, the cans are just placeholders. Eventually they'll probably be replaced with something from a spare plastic kit (F5, maybe).

 

The curved shrouds and corner outlets were formed from thin aluminum sheet laminated with .010" styrene.

 

More to come...

Edited by checksix

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[ Personal side note: as I was writing the previous post, we just received word from our son, a student pilot at Columbus AFB, that he completed his first jet solo flight this afternoon. Yes, in a T-38. We're so happy for him and proud of all the hard work he's done to achieve this. ]

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