The 1/72 Space Shuttle Discovery Project

[jcjchung]

Greetings all,

I've recently started a long term project to model OV-103 in 1/72 scale using the venerable Monogram kit. I've been detailing my progress on my personal hobby facebook page (https://www.facebook.com/jcjchungstudios), and thought I'd also share the progress here for those interested.

One of the first things I've done was to address the kit's cockpit windows. The openings for the main cockpit windows on the Monogram shuttle are oversized and wrongly shaped.



My initial attempt to rectify this was to simply install inserts with the corrected cutouts, but it still didn't look right. I then realized that the fuselage contours themselves are possibly also incorrect; specifically the slopes of fuselage sections containing the windows may be inaccurate.



On the real orbiters these surfaces intersect with the forward fuselage contours, hence the scalloped lower edges. It appears on the kit these surfaces are too steep, causing the two center windows to be too small and the crest between them too shallow, and more importantly the relative sizes of all the windows look off. This is also something that IMHO none of the aftermarket correction sets or decals have rectified perfectly, and it shows, because they attempt to reshape the windows only without addressing the surrounding fuselage geometries.



My final solution involved cutting away the fuselage surfaces entirely and made replacements whose lower edge are placed more forward and at slightly different angles (hatcheted sections). Once in place they look much better to the eyes and especially with the final window cutouts in place.



Cheers,
-jc

[jcjchung]

Following the windows, my next step was to address some of the visual issues I've found of the wings and specifically the leading edge extensions.

The contours of the forward portions of the wing double delta (i.e. the leading edge extension) on the Monogram shuttle has always bothered me, a lot.

On the real deal, this portion has a very distinct, almost sharp, outer edge, whereas the Monogram kit is rather rounded. More importantly, there is a noticeable nose-up attitude of this entire section, starting back from wing RCC panel 5-ish, all the way to the tip at almost straight below the cockpit windows. This portion on the Monogram kit looks almost horizontal in comparison.



Once again, using only the eyeball technique, and the relative spacing of the tip of this wing root to both the entry hatch lower edge and the forward RCS pod outline, I've penciled in a slightly higher wing root contour across its entire fuselage intersect.



I then liberated the entire wing leading edge extension on the port fuselage halve. This was done rather cleanly with the help of Hasegawa Tri-Tool mini saws. The entire piece was then rotated just slightly nose-up, with the tip only about 1/8" higher than where it was initially.



I also recontoured the belly and the chins on the forward fuselage by slitting the plastic at various datum, then individually trimmed, pried, and re-contoured until a smooth transition was achieved. After which the sections were reinforced on the inside with wide strips of styrene doublers to re-establish strength. The beauty about this is that it largely avoids the potentially significant use of filler plastic and putty that would have been required on both the inside and the outside with the traditional fill and sand techniques.



Cheers,
-jc

[jcjchung]

Following the leading edge extension mod, I turned my attention to some of the shape nuances on the wing's leading edges.

Refer to the photos below:

A. Notice where the whole wing leading edge extension starts, and its distinctive 'nose-up' attitude. This has now been addressed.
B. The kink in the wing double-delta starts around here, RCC panel 4-ish. At this point, the tip of the wing is very sharp and low towards the belly, when compared to the kit, which is too bulbous. It also does not have the complete 'dip' appearance, tho that has now been partially addressed with the mods to the leading edge extension.
C. At this point the leading edge camber appears fatter and very much more rounded, compared to the wing edges on either sides. The RCC surfaces immediately above is also somewhat flatter. This is hard to explain, but it's apparent in photos of shuttle wings observed from different angles. Again, not entirely on the kit wings.
D. The rest of the outer wing has a consistent leading edge camber, which again, is much sharper than in the kit. In general, the kit's wings are simply too fat at the leading edge.
E. Somewhat apparent in the comparison photos with the kit, and really apparent if you look at it sideways, the leading edge camber at the wing tip, and perhaps the overall thickness, is simply too fat.





I took a file and coarse sand paper and went at the contours of the upper surfaces of the port side wing and the leading edge extension, and work at it with good ole elbow grease. Figured there was enough plastic for me to grind things down. I think this is about as close as I'll reasonably get, and IMHO, looks a million times better than where the kit started from.







Cheers,
-jc

[jcjchung]

I also did some prelim tests on different approaches to replicating the thermal protection system, using a spare upper wing piece I had lying around. I used the leading edge of the wing since it has the RCC, black thermal tiles, and the white AFRSI all together.

The RCC and black thermal tiles are just straightforward albeit tedious scribe jobs. No biggie.

The AFRSI, in all honesty, vexed me for a long time. The defacto approach in the space modeling community seems to lean on the use of medical tape, which I never liked, for a number of reasons. First, it's tape. It sits proud of the surface and looks like an afterthought. Their edges lift and fray, their materials disallows any rework, and good luck getting paint and decal to nicely blend together. Further, the patterns of most medical tapes are also such that the lines protrude with the tape interior recessed, as opposed to the actual AFRSI where the quilting is recessed and the fabric rising in between as with any cloth material. Also, around each actual AFRSI panel, there is a thin trim around the periphery, which cannot be reproduced with tape.

The test panel here consists of the following approaches to the AFRSI:
- Scribed AFRSI
- Scribed AFRSI flooded with thin white sprue goo
- Tamiya epoxy putty
- Medical tape 



The first two are the AFRSI pattern scribed into the actual plastic. I did two panels, one with just the scribing and second with thin layer of sprue goo to soften it up. This actually turned out the best. I could vary the size of the quilting, the pattern is generally consistent, and I can even vary how soft I want the pattern to be with scribing, the sprue goo, and eventually with primer and paint. It just takes forever to do.

I also tried layering on thin Tamiya epoxy putty and press the quilt pattern into it. This turned out to be trickier than expected, first to get a nice, smooth, level piece of epoxy putty, and then to achieve an even and distinct set of quilted pattern.

The last is with medical tape. Yuck.

So, I've ended up settling on Option 2: scribed FIB with sprue goo. I've leaned away from the epoxy method, for the following reasons. Refer to the attached annotated photos of the test coupon and of the real orbiter.

Also note, going forward I will use the proper term FIB (Flexible Insulated Blankets) when referring to this specific TPS material.

1. The edges of the FIB should be flush against the black tiles (red arrows). Due to the very small scale, it's very difficult to do so consistently. Tho this may be done by recessing the plastic slightly under the edges of the FIB when adjacent to the tiles.
2. Similarly, due to how thin this is (much thinner than 1/35 scale Zimmerit), it's been tricky for me to roll them consistently thin, which also has to be done on the kit surface as doing so separately and then transferring to the model easily wrinkled and damaged the epoxy sheets.
3. Further, when they're not constantly thin, the imprinted pattern show up unevenly (blue and yellow boxes), where as on the actual orbiter they're very clean, flat, and consistent, which I also found easier to replicate with scribing.
4. The edges of the real FIB have an obvious stitched frame (blue arrows). I also found this easier to consistently replicate with scribing.
5. On some of the FIB, there are disc-shaped patches (yellow arrows) that may be easier to replicate with styrene, tho it may also be just as easy to glue small styrene discs to the epoxy.





I understand much of this is splitting hairs and being overly critical on the micro scale. I also don't think any of the above are insurmountable issues, especially if I'm to invest the time and effort either way. however the alternative (Option 2) is already known and works well.

Finally, and this is really just me, I prefer working with styrene whenever possible. If time, effort, and patience aren't really limitations, none of which I'm going to restrict myself on, I have no issues going down the scribing path.

[jcjchung]

The most recent work I've done, after the massive amount of updates above, is cleaning up the forward RCS pod to be used as a test bed for all the approaches to replicating the exterior TPS, which I am to use for the remainder of the project. The forward RCS pod is ideal for being a small, self-contained piece that has both the FIB blankets and and also the HRSI tiles.

I started by taking the rough kit piece, filing off the raised RCS engine outlines, priming, sanding again, and re-primed, to show a nice smooth finished piece.





I then scribed both the HRSI tiles and the FIB blankets onto the forward RCS pod. In general, rough outlines of each pane or sections of panels were located on the piece first with a pencil and templates. My philosophy is that if I can't sketch it with a pencil, I can't scribe with a needle.



Once this is complete the interior or the tile sections and FIB pieces are painstakingly and laboriously scribed in individually. I tried to ensure that the FIB stitch pattern directions are roughly consistent with the actual orbiter's, also.



I have also found that the FIB panels only need to have the exterior framing touched up with sprue goo to give it that rough textured outline. The interiors of the FIB panels do not need to be treated; they're so light that a couple passes of primer is all it took to blend them down.






As of this time, all of the FIB blankets on the forward RCS pod are now complete, as well as the majority of the tiles including all the forward quarter's. Here it is after the initial coat of primer only. Definite amount of work remains to smooth everything over still. Note that the kit's oversized and slightly misplaced center thrusters depressions are also filled. New thruster openings will be drilled and the nozzles will be scratch built and then added.





Thanks for following through on this initial massive sets of updates. To be continued

Cheers,
-jc

[jgoldader]

This is very impressive!  What kind of tool are you using to do the scribing?

[jcjchung]

Thanks. I simply use a sewing needle in a pin vice. Been my go-to for years and years.

For clean up, I always use very fine steel wool to gently remove the raised plastic and gunk by the newly scribed lines. The lines always need to be then lightly reworked again with the needle, then again with the steel wool. This process is repeated a few times until satisfactory





Cheers,
-jc

[mike robel]

Wonderful craftsmanship!

[roma847]

I fully agree with Mike Robel, that's artistic craftwork to which I take my hat off.

However, this is only possible on your comfortable scale, congratulations anyway!

[jcjchung]

Greetings. The forward RCS pod is now complete. The nozzles were opened up with drills and files, and made with Tamiya epoxy putty and formed with a piece of stretched sprue shape into a conical male mold, essentially. Finally, the delta of surface details were scribed in, after which the entire piece was primed with Mr. Surfacer thinned with Mr Color Lacquer Thinner (MLT).

[jcjchung]

I fully agree with Mike Robel, that's artistic craftwork to which I take my hat off.

However, this is only possible on your comfortable scale, congratulations anyway!

Who cares what scale, nobody is comparing. Thanks anyways.

[roma847]

Then try the same procedure in 1/144 ...

[jcjchung]

Then try the same procedure in 1/144 ...

I don't want nor need to. Why are you bringing 1/144 into this?

[roma847]

Hey, you have probably misunderstood me, my comment regarding the scale 1/72 was only a statement and should in no way detract from your great performance ...

[jcjchung]

Hi all. I've been able to experiment with approaches to further enhance the details for the thermal tiles. The goal is to see if it's possible to realistically replicate the serial numbers seen on the orbiter thermal tiles. At 1/72, the markings are actually surprisingly visible. At the resolution I'm scribing the tiles, I also want to go the extra mile to have these replicated, if possible.



The decals were made to include several types of fonts seen on the various tiles across the orbiter. For now, only the white and black serials are tested. In the future I will also include yellow fonts that are seen on some of the black tiles particularly on the ventral fuselage.



The test was done using the same spare wing halve I used to test the FIB panel techniques. A small patch of tiles were scribed, then painted with Mr. Surfacer white and black primers.






The decals were laid directly onto the primer with the help of decal setting solution. Then, a gloss coat was applied overtop, before filters were applied over the graphics on the black tiles to tone them down. Finally, flat overcoats were applied to blend everything together.





I also mocked up the spare wing piece / test mule to the fuselage just to appreciate the effects of the tile decal test coupon. I'm very happy with it. This is the sort of detail that is subtle and does not jump out when viewing the model as a whole, and then the closer you look, the more it reveals itself.







Once again, these tiles are approximately 2mm-wide, and are to-scale for the 1/72 orbiter. It's amazing how much of them are very visible even at this small scale.

[jcjchung]

The vertical stab mods are finally complete, and it is primed and ready to accept thermal protection surface details.





The mods done to correct for the shape issues of the tail took time, mostly because of the various complex faceting across the entire piece. Working with facets is IMHO quite challenging, having to keep the various angles and lines straight and consistent especially during sanding and filling. In addition, obscure details like the base fairing took time to figure out.







The corrections to the vertical tail are as follows (refer to the various attached annotated photos for imagery):

1. The tail is of a hypersonic airfoil design, which has a diamond-shaped cross section (think of X-15 vertical tail or fins on AIM-7 missile). It therefore has a sharp crest at the hinge line, both at the tip and base. The kit fin instead had a very gradual radius that had to be corrected. This was done by slowly building up layers of putty and then carefully sanded down.

2. The rear tip of the kit fin was rounded, and is modified to be chamfered as is on OV-103. Due to the large radius of the kit's fillet, it actually had to be removed and then the area rebuilt by laminating sheet styrene to then have sufficient material to re-trim the tip to the final proper angle.

3. There is a noticeable gap between the rudder and the fin, at both the upper and lower edges. As the kit's rudders were molded with the fin, there was no gap. This was reproduced after the rudder was cut away and reshaped.

4. Both the fin and rudder are chamfered at the upper and lower edges of their interface, and come to a crest. As these chamfers are molded very shallow on the kit, the plastics in this area do not actually reach the centerline of the assembly. This resulted in large gaps of up to 1/4" on both the fin and rudder parts, once latter was liberated. These gaps were filled and built up with laminated sheet styrene to achieve the material needed to reshape and proper chamfers.

5. The kink on the fin side of the lower fin/rudder interface is actually a radius, not a hard line, and was corrected. It only looks like a kink due to the colour* demarcation between the black HRSI tiles and the white FIB blankets.
 
6. The aft edge of the rudder was cut away and rebuilt using parallel strips of thin styrene, to accurately reproduce the small gap between the split rudders. This also achieved the flat aft edges of the rudder due to the shapes of the HRSI (black) thermal tiles, whereas the kit parts actually come to a sharp edge.

7. The brake chute housing and surrounding area were completely scratch built. All the faceting, and edges were researched and reproduced. This was documented in previous posts. The housing geometries are tricky, and care must be taken to ensure the proper relative geometries between all the lines.

8. The base fairings over the fin spar mounting structure were added. This was done by laminating sheet styrene that was then carefully shaved down and then sanded to shape. Determining its geometry was challenging in particular that the aft end of the fairing is not a straight line. Rather, it is comprised of multiple faceted faces that were hard to determine from photos, due to the facet edges and shadows being within the black HRSI tiles area, making accurate visual assessment tricky.

9. The base of the fin is flared out from the leading edge to the above fairing, and is actually a line of HRSI (black) tiles. This was built and shaped with thin sheet styrene.









That just about covers it. I'm sure I missed a few, but you get the jist 🙂

*I'm Canadian, so colour, not color.

[jcjchung]

Scribing of the vertical stab has started, first by laying out the major lines and demarcations for all the tiles and FIB panels, before going into the details. I'll keep the annotation short this time and just let the photos do the talking.

[jcjchung]

The port side of the vertical stab is mostly scribed, including just about all the FIB fabric details fore of the rudder hinge line. Moving onto the starboard now.











And here it is shown with the completed forward RCS piece.



Also, this will be the final update on NASA Space Flight forum. For all future updates, refer to my facebook page: https://www.facebook.com/jcjchungstudios

Cheers.