Space Shuttle Launch Complex 39A with Challenger STS-6 (1:144)

[Spaceman]

Hello everybody,

now it was time to try the white Vallejo primer out of the can.

By the way, it’s been a felt eternity, since the last time I primed/painted something about which I can barely still remember … In addition, these are my first attempts with Vallejo colors/primers, which I want to use shortly.

Each can of Vallejo primer contains two spray heads, namely a Pocket Cap for larger flow rates and medium line widths, ideal for larger surfaces, as well as a Skinny Cap for low flow rates, recommended for fine lines and small details, which is why I have chosen the Pocket Cap.

On this occasion, I then subjected my Suction device (Wiltec) to a first practical test, whereby I started with the small Dummy on the rotary spit.

After switching on, the LED lighting comes on first, and then the fan comes slowly up, which is unmistakeable.

After shaking the spray can for about 1 minute, I started spinning the spit and spraying, but it began quite fogging in because the Dummy was a bit outside the roofing. Maybe I should have used the Skinny Cap with the finer nozzle.

Since I did not want to spray too much primer, I preferred to stop after a few turns, especially as light splashs of primer occurred, which may also have been due to the fact that I had not previously warmed the spray can, which I should rather have done …

And this is now the result of the priming based on the Patterns 2 and 4.

While I can make friends with the Pattern 2 already,

I think that the Pattern 4 with the double tape layer (0,5 mm onto 0,75 mm) seems to be a bit too raised, even though the surface profile will even further be leveled by means of the following airbrushing.

Since the primer layer seemed a bit too thin for me, I also sprayed a second primer to achieve better coverage, whereby I heated the can in the water bath before and shaken it for about 2 minutes.

As one can see in this picture, the layer has also become noticeably denser, which means that the stripes of my favorite Pattern 2 are not so clear visible anymore.

If I now still imagine a multi-layered airbrush finish above, then the surface profile could already go in the right direction, which comes closer to the original images of the SOFI pattern.

On this picture you can see the area in the lower part, which I had twice floured.

And this is now the larger Dummy with the five patterns after comparable (short) priming time, for which I had used the Pattex Spray Adhesive, which might not have had the optimal adhesive power, what led to a slighty too thin flour layer.

On this picture one can see, that at the Pattern 3 the MEK-gluing of the Evergreen Strips has partially resolved.

And so it looks after the two-time priming.

Conclusion:
After all, what I have seen so far, I would prefer the Pattern 2.

Now it remains to wait for the effect of the airbrushing, whereby I slowly have to think about the orange-brown color mixture, although for the test-painting initially a simple color is sufficient.

[amoz02t]

Love it! Great work

[Spaceman]

Thanks Stuart,

do you know what ET this is, I think one of the later missions, right?

[Spaceman]

Hello folks,

now it’s time to think about the orange colors for the ET soon, then I can airbrush the dummies and compare the effect of the primed flour coating.

With the orange-colored shades of the External Tank (ET) I have been engaged oftener already, and it is known that the increasing discoloration of the ET towards darker shades is related to solar radiation, the Shuttle stack is exposed to, while it is standing on the launch pad waiting for the launch.

Consequently, one will not be able to get along with one hue alone, because the Intertank is darker anyway, but rather one needs some more or less intense orange-brown color blends, depending on which Countdown situation one wants to display on the launch pad, which is a matter of opinion.

Originally, I had thought of the Countdown phase right before the launch for my Diorama and so far I had oriented myself by my often shown STS-6 Reference photo, on which the shades of the ET appear relatively bright, but without knowing which phase this photo comes from exactly. But since the Payload canister can be seen, the photo should be from the beginning of January 1983.

Source: retrospaceimages.com (STS-6)

Similarly bright shades can be seen on the pictures at the Roll-out of the ET-8 (09/10/1982),

Source: forum.nasaspaceflight.com (Jester)

as well as during the Roll-out of the Challenger (11/30/1982), here in the fog shortly in front of the Pad 39A.

Source: NASA

On this photo from the Lift-off (04/04/1983) the ET shades appear much darker, a detail that I did not attach much importance to for a long time, because the whole mood of the photo appears somehow darker, which might have been due to the weather or to the photo itself.

Source: NASA

However, this strong discoloration of the ET becomes plausible given the unusually long resting time of the Shuttle stack on the pad, which at STS-6 in contrast to other missions with 4 months lasted much longer than originally foreseen, which would have been the main reason.

The reason for the delay in the launch, which was originally scheduled for the end of January 1983, was a hydrogen leak in the area of Main engine SSME No. 1 of the orbiter that occurred during a test run, Flight Readiness Firing (FRF - 12/18/1982), but which could not be localized exactly at first.

In this Flight readiness test, which every orbiter has to complete before his maiden flight or after major technical overhauls, i.a. the three main engines are tested to prove their full functionality for approx. 20 seconds and then shut down.

Here is an image of this FRF, which I initially thought was a launch image, but with its brighter color shades of the ET it does not fit to the Lift-off image with the dark hues, what has been pretty confusing me at the beginning.

Source: NASA

Luckily, in the NSF forum there is a special, very detailed and highly interesting thread Challenger STS-6 – A Walk into History with a lot of photos and information over the entire course of this first Challenger mission, which was a great support for me for understanding all the operations.

This leak and its exact locating has kept NASA busy for quite a long time and led to a delay in the launch date, as major maintenance work had to be done on the orbiter’s main engines.

Therefore, it was necessary to perform another FRF test (01/25/1983), where it can be seen on this photo that the colors of the ET had darkened further.

Source: forum.nasaspaceflight.com (Ares67)

But even during this FRF, a hydrogen leak occurred, which was caused by a 3/4 inch long hairline crack in the combustion chamber manifold of the Engine SSME No. 1.

Since in the other engines further leaks occurred too, which were obviously a problem of the welds of these new engines, then at the beginning of March 1983, all three main engines were dismantled on the launch pad.

Source: mainengine.de

While the welds at the two Engines SSME No. 2 and No. 3 were reinforced, engine SSME No. 1 was replaced by a new engine whose welds were also reinforced for safety’s sake.

After detailed error analysis and a problem-free test of the last 16 hours of a normal countdown, the engines were reinstalled on 03/10/1983, after which the Challenger finally could start for her Maiden flight (04/04/1983.

So I know now, when the ET-8 had which kind of shades, and I can decide accordingly, whereby today I tend but rather to the lighter shades.

[amoz02t]

Manfred- No. Sorry. I do not know which tank this one was as I just liked the beanie cap image.

[Spaceman]

Yep Stuart, it’s really an amazing cap.

[Spaceman]

Hello everybody,

and thus again back to the color shades of the External Tank, wherfore I’ve looked at my STS-6 Reference photo once again more exactly, to be able to assign them to the available Vallejo colors, whereto I am focused on the sprayable colors from the range Model Air (MA).

Source: retrospaceimages.com (STS-6)

After careful viewing, I have come to the conclusion that this image is not so well suited for determining the color shades, since half of the ET is more or less covered by the shuttle or the right half of the ET is also still shaded.

Therefore, I have now selected this photo of the first FRF (12/18/1982) for the further detailed consideration, on which the ET seems to be illuminated relatively evenly.

Source: NASA

As one can see, the ET colors are in my opinion less orange-brown color shades than rather yellow-brown shades.

First of all, I tried using my Paint Shop Pro (Jasc) to determine the RGB codes of the different color shades in order to get a better feeling for the colors.

Concerning the indicated RGB values, it should be noted that the values in the vicinity of the destination vary slightly and thus cannot be considered as absolute values.

One can also consider the classic RAL Color Chart what I’ve tried in this image for three places on the LH2 Tank/Intertank based on the color Ochre brown RAL 8001. And as one can see, one gets quite close to the ET color shades by adjusting the brightness.

In all these comparisons, however, it is important to note that even the normalized RAL colors do not appear completely authentic on PC monitors and the color rendition depends on the respective screen settings anyway, whereby color comparisons are complicated or have to be taken with care.

Since one cannot get any further with the RAL colors in the practical color selection, I finally got back to the Vallejo-Model Air assortment to find corresponding colors, which I then also can order.

Thereby I came across the following three colors, whose brightness I then adjusted gradually, resulting in the darker shades.

– Vallejo Model Air 71.033 – Ochre Yellow for the LO2/LH2 tank with the color shades B-20, B-30, B-40,

– Vallejo Model Air 71.077 – Wood for the Intertank (B-20),

– Vallejo Model Air 71.076 – Skin Tone for the lighter areas (B-20)

In this image, the selected color shades (marked blue) are placed on the appropriate places on the ET that match well with the ET shades.

So I’ll order these three airbrush colors first, and I’m curious how they’ll even come out. The only question is, what other colors I should mix with the original colors to get the darker shades?

Here is an overview of the Model Air colors, in which I have marked the three colors.

Perhaps for the MA71.033 and the MA71.077 the darker neighbor color MA71.034 would be suitable, and for the MA71.076 maybe the MA71.077?

For useful hints or suggestions I would be grateful.

[Dioramartin]

I think I’d work backwards from where this masterpiece will be exhibited, specifically under what kind of illumination – daylight (i.e. natural indoor light through windows), or artificial light (cool, warm, “daylight”) ? Or both depending on the time of day?

I’m sure you’ll experiment on some scrap plastic first. As for darkening a colour, it might be worth trying a tiny droplet of the opposite colour (consult a spectrum wheel), and black, and as you said a slightly darker shade of the original colour. You might find that the first works better than the second & third, although it’ll be incredibly subtle.

Going to this level of colour-matching is fantastic, but even if you get perfect theoretical matches, in practice they may still look “off” in certain lights. Whatever, I think you will get so close to “correct” that nobody in the world (apart from you ) will be able to detect anything wrong.

[Johnnych01]

That is some serious detective workmen the colour matching …but a very necessary one. And along Tim, I think whichever you pick for the final versions, they will be looking spot on to us shuttle tank laymen …

[Spaceman]

Yep Tim and John, I fully agree with you, the colour-matching of the ET is really a tricky chapter and a true challenge.

[Spaceman]

Hello everybody,

after I’ve printed out my new Reference photo with the selected brighter ET color shadings,

now I’m going to order the matching Vallejo Model Air Colors together with the associated Airbrush Thinner.

Source: modellbau-universe.de

Actually, I had so far assumed that the Model Air Colors in the practical dropper bottles are already sprayable.

That this is not the case, I have learned now in this interesting video by Jens Kaup, in which he gives important tips for working with Vallejo colors that should be considered.

Important tip for working with Vallejo colors

The video is unfortunately only in German, but it is very vivid and therefore hopefully understandable.

In that he says, that as practical as the dropper bottles from Vallejo are, the poor color mixing is a problem, wherfore relief is provided. The consistency of the Model Air colors is too thick for fine airbrushing. Here it helps to fill up each new color vial simply with Vallejo Thinner,

and to insert a Stainless steel hex nut M5 as shaking aid for better mixing.

Of course, Stainless steel balls (0,25 inch) fulfill the same purpose.

Conclusion: Two simple measures with great effect!

[Spaceman]

Hello everybody,

my ordered Vallejo colors (7x Model Air, 2x Model Color, 1x Thinner) have arrived meanwhile, and I did buy a handful of Stainless steel nuts M5 too,

so I could actually start with some mixing tests.

[Petro]

It is really interesting to see the amount of research you are doing.

The whole paint matching sequence or what ever you want to call it is fascinating.

[Spaceman]

Hello everybody,

but there is another interesting source, and this is this Airbrush Beginner Course CD - Heinz Wagner,

Source: Heinz Wagner

which I had bought a long time ago and have now looked again. Therein my friend Heinz is presenting his Test method for testing and determination of the sprayability of colors that is simple yet ingenious.

First, I did insert a M5 Stainless steel nut as a mixing aid into all Vallejo vials, as described in the video by Jens Kaup, which I’ve shown already.

Then I did shake each vial for 3 minutes,

as recommended on Heinz Wagner’s CD, whereby I could hear the clacking of the nuts when shaking the Model Air colors, but not at the two Model Color colors (2nd row on the right) what suggests that they are thicker and therefore not sprayable at all, as indicated in the video, which is why a diluting with water 1:1 to 1:2 should take place.

Source: Airbrush Beginner Course CD (Heinz Wagner)

And now to his simple Test method, whereby holding the vial on the top of a ruler (30 cm),

Source: Airbrush Beginner Course CD (Heinz Wagner)

and let dropping a drop from that height.

Source: Airbrush Beginner Course CD (Heinz Wagner)

And if the diameter of this color point is between 11 mm and 14 mm, the color should be sprayable in the opinion of the Airbrush Guru Heinz Wagner.

Source: Airbrush Beginner Course CD (Heinz Wagner)

And then I tried that,

first for the Model Air 71.033 (Yellow Ochre). But to my astonishment the diameter of the color point was < 10 mm.

And since the tests with the next three Model Air colors have shown this surprising result too,

then I started carefully to add a few drops of the Vallejo Thinner step by step (3, 6, 10, 15 drops), then did shake again for three minutes and retested, but without getting drops > 10mm, which has disillusioned me pretty much.

During dripping I also noticed that sometimes at first only a bubble comes out of the dropper and only then the color comes, and that the drops of paint on the paper have sometimes even contained air bubbles, which may possibly falsify the result.

The following tests I have done on glossy paper, the first tests on the other hand on normal copy paper, because the absorbency of the paper could probably also have an influence on the diameter of the color points, I think, right?

After that I was stumped and a nervous wreck and have communicated these results Heinz Wagner, in the hope that he has an explanation.

[Spaceman]

Hello everybody,

in the meantime I 've grabbed the brush and started to mix the first ET colors.

I started with the sprayable-thinned Vallejo Model Air 71.033 (ochre), which I wanted to darken a little with the help of the Vallejo Model Air 71.034 (sand brown).

For this I have filled 4 drops of the MA 71.033 in a crown cork and placed it next to my test drop on the image, whereby this shade corresponds pretty well with the bright ET color tone in the lower part.

Then I added a drop of the MA 71.034 to it and mixed it with the brush, what corresponds about a shade between MA 71.033-B-30 and B-40,

whose test brushstroke I’ve put on the lower ET area,

and in front at the Nose cone that of pure color MA 71.033.

And already with this mixture, some of the shades can be quite well represented, I think.

And so I will now also test the shades of the other two colors MA 71.076 (skin color) and MA 71.077 (wood).

[Spaceman]

Hello everybody,

and so the mixing went on.

As previously announced, I first tried mixing the lighter color shade, namely from the two colors MA 71.076 (Skin Tone) and MA 71.077 (Wood),

whereby I have dripped one drop of each color in the crown cap, which already run into each other here.

And so the mix of both colors looks like.

And as one can see in the reference photo, the shade of the mixture (1:1) is almost perfectly hit right away.

Then I also tried mixing the darker color shade of the IT for which now still the color MA 71.034 (Sand Brown) comes into play, which I’ve mixed together with the MA 71.077 (Wood) in several tests with different proportions MA 71.077: MA 71.034, whereby I’ve slowly felt my way, from 1:1, over 2:1 and 3:1, up to 4:1.

Here is the comparison in the mixing ratio 3:1 to see, which already fits relatively well to the IT’s color shade, whereby 2:1 looks similar.

And here all previous color shades are to see once again.

After comparing the Mix shades on paper now the comparison on the white primer on the Flour&Strip Texture of the ET Dummy is to be done, which will give yet the final indication of how well the shades actually fit the reference photo, whereon I’m very curious.

[Spaceman]

Hello friends,

here are the first pictures of the Mix color shades on the both floured and partly twice primed dummies with the five different Stripe patterns, whereby I have applied the colors not by airbrush, but with the brush.

In the foreground of the following color-tone comparisons stands my favored Pattern 2, consisting of single turns of 0,75 mm Tape (distance 0,5 mm), glued as a continuous spiral (Barber pole).

The three Mix color shades in the following picture correspond to the last preferred MA Mixtures,

Mix-1 - MA 71.076 (Skin Tone) : MA 71.077 (Wood) - 1:1

Mix-2 - MA 71.033 (Ochre) : MA 71.034 (Sand Brown) - 4:1

Mix-3 - MA 71.077 (Wood) : MA 71.034 (Sand Brown) - 3:1

here again from a slant position.

And this is the comparison on the short dummy, which was both once and double floured,

which can be seen even more clearly here at the border between the two areas once again.

And this is the Mix-1 on the once-floured area.

These are the Mix color shades on the two dummies in a vertical arrangement, first on the big dummy,

and here on the short dummy, where the simple flour state seems to me almost as sufficient.

And finally still the comparison of the three Mix color shades with the reference photo, whereby the Mix-1 fits best to the brighter areas of the Closeouts.

In contrast, in my opinion at the Mix-2 for the LH2 tank,

and even more so at the Mix-3 for the Intertank is still missing a little bit of Orange.

These two color shades came out much better on paper,

wherefore I have still to modify their mixture by adding a bit more Orange.