In my last post, I still had a few bits and pieces of scratch building to do—a stills camera tucked behind the starboard sponson, facing backwards, and some weapons mount points.
I haven’t been able to find any good views of the stills camera beyond a couple glimpses in Todd Douglas Miller’s Apollo 11 documentary:
What does seem to be the case is that (in contrast to the rear pairs) the paired forward mount points weren’t in use beyond the single camera mount. So I put together an “artist’s impression” of a stills camera on a mount, swathed in the ubiquitous yellow tape, and I cannibalized the kit’s forward weapon mounts to build the necessary rear mounts, looking something like what I can see in photographs. It’s all a little unsatisfactory, but it’s the best I could come up with.
I also spent a little time getting the Belcher Bits resin sponsons mated to the kit parts. These are very nicely moulded, and just need the locating holes for the upper sponson struts to be drilled a little deeper, and bit of chiselling and filling around the lower supports. Here they are, taped in place while waiting for the epoxy to dry:
I have a suspicion the final alignment may make the undercarriage a little “in-toed” but I can cross that bridge when I come to it.
And here they are, filled and primed:
I’m going to paint them separately and only attach them late in the build process.
The Hasegawa SH-3D instruction sheet I downloaded from Scalemates wants me to attach something to the back underside of the starboard sponson—it’s made of two pieces from sprues that don’t come with the SH-3H kit.
But a look at images of the real helicopter show no external feature in this location:
The good people over at Britmodeller tell me that this is, in fact, a recessed spotlight in a square well. I doubt if I can create such a thing successfully by burrowing into a solid resin part, so I’ll try to suggest its presence with paint instead.
Another object that isn’t included in the SH-3H kit but which was present in the real helicopter is a fin of some kind on the underside, which I scratch-built for styrene card. While I was at it, I scratch built another little fin for the underside. This one was include in the kit, but departed from my tweezers towards parts unknown almost as soon as I freed it from the sprue. Here’s the underside with fins added, the blanked sonar well in place, and all the various bumps and ridges detailed in my last post removed:
Another little challenge on the underside of the model are three small light fittings, for which there are no paint masks on the Montex sheet. I’m not very good at cutting tiny discs out of masking tape, and after a bit of thought I put a strip of Tamiya tape on to an offcut of styrene sheet, and punched out some suitable sized holes with a leather punch. After a few attempts, I ended up with some neat masking discs I could peel off the punched-out styrene and put in place:
Now I just need to remember to remove them once the model is completed.
As well as removing lumps and bumps from the port fuselage I had to get rid of the window just aft of the door. I glued the transparent part in place and then filled and sanded the outside. If I was doing it again I’d sand off the window frame (moulded into the transparent part) before putting the window in place—that would have made filling and sanding easier. The final result looks OK after a light coat of grey primer:
On the starboard side, more lumps and bumps were removed, and I added the two runs of cable that will eventually connect to my two scratch-built camera mounts:
That’s it for now. It seems like a lot of work for little progress, but next time things should actually start looking like a helicopter.
In my previous post on this topic, I described how flight engineers working on the Apollo programme assigned XYZ coordinate axes to the Saturn V launch vehicle and to the two Apollo spacecraft, the Command/Service Module (CSM) and the Lunar Module (LM). This time, I’m going to talk about how these axes came into play when the launch vehicle and spacecraft were in motion. At various times during an Apollo mission, they would need to orientate themselves with an axis pointing in a specific direction, or rotate around an axis so as to point in a new direction. These axial rotations were designated roll, pitch and yaw, and the names were assigned in a way that would be familiar to the astronauts from their pilot training. To pitch an aircraft, you move the nose up or down; to yaw, you move the nose to the left or right; and to roll, you rotate around the long axis of the vehicle.
These concepts translated most easily to the axes of the CSM (note the windows on the upper right surface of the conical Command Module, which indicate the orientation of the astronauts while “flying” the spacecraft):
With the astronauts’ feet pointing in the +Z direction as they looked out of the windows on the -Z side of the spacecraft, they could pitch the craft by rotating it around the Y axis, yaw around the Z axis, and roll around the X axis.
The rotation axes of the LM were similarly defined by the position of the astronauts:
Looking out of the windows in the +Z direction, with their heads pointing towards +X, they yawed the LM around the X axis, pitched it around the Y axis, and rolled it around the Z axis.
For the Saturn V, the roll axis was obviously along the length of the vehicle, its X axis.
But how do you decide which is pitch and which is yaw, in a vehicle that is superficially rotationally symmetrical? It turns out that the Saturn V was designed with a side that was intended to point down—its downrange side, marked by the +Z axis, which pointed due east when the vehicle was on the launch pad. This is the direction in which the space vehicle would travel after launch, in order to push the Apollo spacecraft into orbit—and to do that it needed to tilt over as it ascended, until its engines were pointing west and accelerating it eastwards. So the +Z side gradually became the down side of the vehicle, and various telemetry antennae were positioned on that side so that they could communicate with the ground. You’ll therefore sometimes see this side referred to as the “belly” of the space vehicle. And with +Z marking the belly, we can now tell that the vehicle will pitch around the Y axis, and yaw around the Z axis.
If you have read my previous post on this topic, you’ll know that the astronauts lay on their couches on the launch pad with their heads pointing east.* So as the space vehicle “pitched over” around its Y axis, turning its belly towards the ground, the astronauts ended up with their heads pointing downwards, all the way to orbit. This was done deliberately, so that they could have a view of the horizon during this crucial period.
But the first thing the Saturn V did, within a second of starting to rise from the launch pad, was yaw. It pivoted through a degree or so around its Z axis, tilting southwards and away from the Launch Umbilical Tower on its north side. Here you can see the Apollo 13 space vehicle in the middle of its yaw manoeuvre:
This was carried out so as to nudge the vehicle clear of any umbilical arms on the tower that had failed to retract.
Then, once clear of the tower, the vehicle rolled, turning on its vertical X axis. This manoeuvre was carried out because, although the belly of the Saturn V pointed east, the launch azimuth could actually be anything from 72º to 108º, depending on the timing of the launch within the launch window. (See my post on How Apollo Got To The Moon for more about that.) Here’s an aerial view of the two pads at Launch Complex 39, from which the Apollo missions departed, showing the relevant directions:
An Apollo launch which departed at the start of the launch window would be directed along an azimuth close to 72º, and so needed to roll anticlockwise (seen from above) through 18º to bring its +Z axis into alignment with the correct azimuth, before starting to pitch over and accelerate out over the Atlantic.
Once in orbit, the S-IVB stage continued to orientate with its belly towards the Earth, so that the astronauts could see the Earth and horizon from their capsule windows. This orientation was maintained right through to Trans-Lunar Injection (TLI), which sent the spacecraft on their way to the moon.
During the two hours after TLI, the CSM performed a complicated Transposition, Docking and Extraction manoeuvre, in which it turned around, docked nose to “roof” with the LM, and pulled the LM away from the S-IVB.
This meant that the X axes of CSM and LM were now aligned but opposed—their +X axes pointing towards each other. But they were also oddly rotated relative to each other. Here’s a picture from Apollo 9, taken by Rusty Schweickart, who was outside the LM hatch looking towards the CSM, where David Scott was standing up in the open Command Module hatch.
The Z axes of the two spacecraft are not aligned, nor are they at right angles to each other. In fact, the angle between the CSM’s -Z axis and the LM’s +Z axis is 60º. This odd relative rotation meant that, during docking, the Command Module Pilot, sitting in the left-hand seat of the Command Module and looking out of the left-hand docking window, had a direct line of sight to the docking target on the LM’s “roof”, directly to the left of the LM’s docking port.
Once the spacecraft were safely docked, roll thrusters on the CSM were fired to make them start rotating around their shared X axis. This was called the “barbecue roll” (formally, Passive Thermal Control), because it distributed solar heating evenly by preventing the sun shining continuously on one side of the spacecraft.
Once in lunar orbit, the LM separated from the CSM and began its powered descent to the lunar surface.† This was essentially the reverse of the process by which the Saturn V pushed the Apollo stack into Earth orbit. Initially, the LM had to fire its descent engine in the direction in which it was orbiting, so as to cancel its orbital velocity and begin its descent. So its -X axis had to be pointed ahead and horizontally. During this phase the Apollo 11 astronauts chose to point their +Z axis towards the lunar surface, so that they could observe landmarks through their windows—they were flying feet-first and face-down. Later in the descent, as its forward velocity decreased, the LM needed to rotate to assume an ever more upright position (-X axis down) until it came to a hover and descended vertically to the lunar surface. So later in the powered descent, Armstrong and Aldrin had to roll the LM around its X axis into a “windows up” position, facing the sky. Then, as the LM gradually pitched into the vertical position, with its -X axis down, the +Z axis rotated to face forward, giving the astronauts the necessary view ahead towards their landing zone.
Finally, at the end of the mission, the XYZ axes turn out to be important for the re-entry of the Command Module (CM) into the Earth’s atmosphere. The CM hit the atmosphere blunt-end first, descending at an angle of about 6º to the horizontal. But it was also tilted slightly relative to the local airflow, with the +Z edge of its basal heat-shield a little ahead of the -Z edge. This tilt occurred because the centre of mass of the CM was deliberately offset very slightly in the +Z direction, so that the airflow pushed the CM into a slightly tilted position. This tilt, in turn, generated a bit of lift in the +Z direction—which made the Command Module steerable. It entered the atmosphere with its +Z axis pointing upwards (and the astronauts head-down, again, with a view of the horizon through their windows). The upward-directed lift prevented the CM diving into thicker atmosphere too early, and reduced the rate of heating from atmospheric compression.
Later in re-entry, the astronauts could use their roll thrusters to rotate the spacecraft around its X axis, using lift to steer the spacecraft right or left, or even rolling it through 180º so as to direct lift downwards, steepening their descent if they were in danger of overshooting their landing zone.
* As described in my previous post on this topic, the coordinate axes of the CSM were rotated 180º relative to those of the Saturn V—the astronauts’ heads pointed in the -Z direction of the CSM, but the +Z direction of the Saturn V.
† I’m missing out a couple of steps here, in an effort to be succinct. (I know, I know … that’s not like me. Take a look at NASA Technical Memorandum X-58040 if you want to know all the details.)
Trouble is, 1/48 scale kits for the SH-3D version of the Sea King are rare and correspondingly expensive. But there is a fairly well-trodden route involving the conversion of an SH-3H, such as the Hasegawa one I’m using here.
So I’ve got the kit, and the decals. I also have a set of short SH-3D-style sponsons (to replace the long SH-3H versions) from Belcher Bits, a set of Montex paint masks for the windows and cockpit canopy, and the instruction sheet for the rare Hasegawa SH-3D kit, downloaded from Scalemates. And, it turns out when I open the Hasegawa box I bought on eBay, I also have a set of QuickBoost resin replacement seats and an Eduard photoetch cockpit detail set. This is the second time I’ve found extras squirrelled away inside a second-hand kit, which kind of compensates for the times I’ve found parts missing from other eBay kits.
First up, some of the kit parts require modification. Hasegawa’s SH-3D kit used the same fuselage parts as the SH-3H, so it provides some good information on which of the kit’s various lumps and bumps need to be removed. There’s also the small matter of a window that needs to be filled on the port side.
Note: Here I need to intrude with the benefit of hindsight, to say that the SH-3D instructions are wrong when they indicate the removal of the two raised octagonal structures on the underside of the aircraft. These aerials are visible in photographs of the real thing, and should be left in place. Later in this build log I’ll report on how I had to build replacements, having dutifully removed the originals.
Then the horizontal stabilizer needs to be shortened and its supporting strut discarded, with the locating holes filled.
I rounded the end of the shortened stabilizer with a little filler.
I also needed to remove the dipping sonar from its well on the underside of the aircraft. The well and the tip of the sonar probe come moulded as a single part from Hasegawa, so I sawed them apart.
I’ll blank off the sonar well with some styrene sheet—it was blanked at floor level in the real aircraft, too.
Next, there’s some scratch building. The Gemini and Apollo recovery helicopters were fitted with a rack of cameras, attached to the aft weapon mount point on the starboard side, to film and photograph the recovery process. Todd Douglas Miller’s excellent documentary, Apollo 11, provided some good views of this object. Here are three screen grabs from that film, together with a blurry detail from a more distant photograph:
There was a lot of sticky-tape engineering involved. Starfighter decals provide a yellow strip to help reproduce this appearance, but to my eye it’s too orange, so I printed up my own decal sheet to produce the necessary strips of colour.
Here’s the final result for the camera mount, cobbled together from bits of styrene and half-millimetre brass rod:
Also required is a pair of Search And Rescue Homing antennae, mounted on the sponson struts. Here they are in a view of the Apollo 8 recovery:
And here’s my effort using styrene, brass rod and stretched sprue:
I’ve also got a couple of pending jobs. There was also a stills camera mounted behind the starboard sponson, pointing aft, presumably attached to a forward weapon mount point, but I’ve yet to discover any kind of detailed view of this. And it’s clear from the camera-mount photographs that a weapon mount was still in place just forward of the camera mount; a pair were also in place on the other side of the aircraft, as can be seen from the Hasegawa SH-3D box art photograph:
These are different from the parts provided in the kit, and I’m going to need to scratch build them, too. And again, decent photographs are difficult to find.
But in the meantime, I’ve assembled the cockpit. This is SH-3H in detail, but I figured that if I tried to revise the appearance, I’d end up with something that looked much less effective, and which in any case would be poorly seen through the kit canopy:
I also masked up and painted the interior of the canopy, including the green-tinted top windows. This last part was done using Tamiya Clear Green, which I found a bit of a bugger to spray evenly.
In the next instalment, I’ll start putting some of these parts together.
As a matter arising from my long, slow build of a Saturn V model, I became absorbed in the confusing multiplicity of coordinate systems and axes applied to the Apollo launch vehicle and spacecraft. So I thought I’d provide a guide to what I’ve learned, before I forget it all again. (Note, I won’t be talking about all the other coordinate systems used by Apollo, relating to orbital planes, the Earth and the Moon—just the ones connected to the machinery itself. And I’m going to talk only about the Saturn V launch vehicle, though much of what I write can be transferred to the Saturn IB, which launch several uncrewed Apollo missions, as well as Apollo 7.)
First up, some terminology. The Saturn V that sent Apollo on its way to the Moon is called the launch vehicle, consisting of three booster stages, with an Instrument Unit on top, responsible for controlling what the rest of the launch vehicle does. Sitting on top of the launch vehicle, mated to the Instrument Unit, is the spacecraft—all the specifically Apollo-related hardware that the launch vehicle launches. This bit is sometimes also called the Apollo stack, since it will eventually split up into two independent spacecraft—the Lunar Module (LM) and the Command/Service Module (CSM). The combination of launch vehicle and spacecraft (that is, the whole caboodle as it sat on the launch pad) is called the space vehicle.
The easiest set of coordinate axes to see and understand were the position numbers and fin letters which were labelled in large characters on the base of the Saturn V’s first stage, the S-IC. You can see them here, in my own model of the S-IC:
In this view you can see fins labelled C and D, and the marker for Position IIII, equidistant between them.
The numbering and lettering ran anticlockwise around the launch vehicle when looking down from above, creating an eight-point coordinate system of lettered quadrants (A to D) with numbered positions (I to IIII) between them, which applied to the whole launch vehicle. They marked out the distribution of black and white stripes—each stripe occupied the span between a letter and a number, with white stripes always to the left of the position numbers, and black stripes to the right. The five engines of the S-IC and S-II stages were each numbered according to the lettered quadrant in which they lay, with Engine 5 in the centre, Engine 1 in the A quadrant, Engine 2 in the B quadrant, and so on. The curious chequer pattern of the S-IVB aft interstage (the “shoulder” where the launch vehicle narrows down between the second and third stages) is distributed in the lettered quadrants, with A all black, B black high and white low, C white high and black low, and D all white.*
Position II of the launch vehicle was the side facing the Launch Umbilical Tower (LUT), so that side of the Saturn V was dotted with umbilical connections and personnel access hatches, as well as a prominent vertical dashed line painted on the second stage, called the vertical motion target, which made it easy for cameras to detect the first upward movement as the space vehicle left the launch pad. You don’t often get a clear view of the real thing from the Position II side, so I’ve marked up the appropriate view of my model instead, at left.
The two Cape Kennedy launch pads used for Apollo (39A and 39B) were oriented on a north-south axis, with the LUT positioned on the north side of the Saturn V, so Position II faced north. Position IIII, on the opposite side, faced south, looking back down the crawler-way along which the Saturn V had been transported on its Mobile Launcher Platform. Position IIII was also the side that faced the Mobile Service Structure, which was rolled up to service the Saturn V in its launch position, and then rolled away again before launch. And so Position I faced east, which was the direction in which the space vehicle had to travel in order to push the Apollo stack into orbit.
These letters and numbers seem to have been largely a reference for the contractors and engineers responsible for assembling and mating the different launch vehicle stages. Superimposed on them were the reference axes used by the flight engineers, who used them to talk about the orientation and movements of the launch vehicle and the two Apollo spacecraft. These axes were labelled X, Y and Z.
For the launch vehicle, LM and CSM the positive X axis was defined as pointing in the direction of thrust of the rocket engines. So the end with the engines was always -X, and the other end was +X. The +Z direction was defined as “the preferred down range direction for each vehicle, when operating independently”. For the launch vehicle, that’s straightforward—downrange is to the east as it sits on the pad (the direction in which it will travel after launch), so +Z corresponds to Position I, and -Z to Position III. The Y axis was always chosen to make a “right-handed” coordinate system, so +Y points south through Position IIII.
In the image below, we’re looking north. Once the Saturn V has launched it will tip over and head eastwards (to the right) to inject the Apollo stack into orbit.
These axes were actually labelled on the outside of the Instrument Unit (IU), at the very top of the launch vehicle. Here’s one in preparation, with the +Z label flanked by the casings of two chunky directional antennae—a useful landmark I’ll come back to later.
So here’s a summary of all the axes of the Saturn V:
Moving on to the Lunar Module, its downrange direction is the direction in which it travels during landing, when it is orientated with its two main windows facing forward—so +Z points in that direction, out the front. The right-hand coordinate system then puts +Y to the astronauts’ right as they stand looking out the windows.
The landing legs were designated according to their coordinate axis locations. In the descent stage, between the legs, were storage areas called quads—they were numbered from 1 to 4 anticlockwise (looking down), starting with Quad 1 between the +Z and -Y leg. The ascent stage, sitting on top of the descent stage, had four clusters of Reaction Control System (RCS) thrusters, which were situated between the principal axes and numbered with the same scheme as the descent-stage quads.
But it’s not clear that there is a natural downrange direction for the CSM—the +Z direction is defined (fairly randomly, I think) as pointing towards the astronauts’ feet, with -Z therefore corresponding to the position of the Command Module hatch. That places +Y to the astronauts’ right side as they lie in their couches.
The Command Module was fairly symmetrical around its Z axis, and its RCS thrusters were neatly place on the Z and Y axes. Not so the Service Module, which was curiously skewed. Its RCS thrusters, arranged in groups of four called quads, were offset from the principal axes by 7º15′ in a clockwise direction when viewed from ahead (that is, looking towards the pointed end of the CSM). The RCS quad next to the -Z axis was designated Quad A; Quad B was near the +Y axis, and the lettering continued in an anticlockwise direction through C and D. I’ve yet to find out why the RCS system was offset in this way, since it would necessarily produce translations and rotations that were offset from the “natural” orientation of the crew compartment, and from the translations and rotations produced by the RCS system of the Command Module.
The Service Module also contained six internal compartments, called sectors, numbered from 1 to 6. These were symmetrically placed relative to the RCS system, rather than the spacecraft’s principal axes. Finally, the prominent external umbilical tunnel connecting the Service Module to the Command Module wasn’t quite on the +Z axis, but offset by 2º20′ in the same sense as the RCS offset.
So those are the axes for the launch vehicle and spacecraft. But how did they line up when the Saturn V and Apollo stack were assembled? Badly, as it turns out.
First, the good news—all the X axes align, because the spacecraft and launch vehicle are all positioned engines-down for launch, for structural support reasons, if nothing else.
With regard to Y and Z, it’s easy to see the CSM’s orientation on the launch pad. Here’s a view from the Launch Escape Tower, which we’ve established (see above) is on the -Y side of the launch vehicle. The tunnel allowing access to the crew hatch of the Command Module (-Z) is on the left, and the umbilical tunnel connecting the Service Module to the Command Module is on the right (+Z), so the CSM +Y axis is pointing towards us.
Oops. The CSM YZ axes are rotated 180º relative to those of the Saturn V launch vehicle.
It’s more difficult to find out the orientation of the Lunar Module within the Apollo stack, since it’s concealed inside the shroud of the Spacecraft/Lunar Module Adapter. Various diagrams depict it as facing in any number of directions relative to the CSM, but David Weeks’s authoritative drawings show it turned so that its +Z and +Y axes align with those of the CSM—facing to the right in the picture above, then, with its YZ axes rotated 180º relative to those of the Saturn V launch vehicle below. We can check that this is actually the case by looking at photographs of the LM when it’s exposed on top of the S-IVB and Instrument Unit, during the transposition and docking manoeuvre. The viewing angles are never very favourable, but the big pair of directional antennae flanking the +Z direction on the IU are useful landmarks (see above).
We can see that the front of the Lunar Module (+Z) is indeed pointing in the opposite direction to the directional antennae marking the +Z axis of the IU and the rest of the launch vehicle. Weeks’s drawing are correct.
So, sitting on the launch pad, the axes of the launch vehicle are pointing in the opposite direction to those of the spacecraft. NASA rationalized this situation by stating that:
A Structural Body Axes coordinate system can be defined for each multi-vehicle stack. The Standard Relationship defining this coordinate system requires that it be identical with the Structural Body Axes system of the primary or thrusting vehicle.
So the whole space vehicle used the coordinate system of the Saturn V launch vehicle, and the independent coordinates of the LM and CSM didn’t apply until they were manoeuvring under their own power.
So, beware—there’s real potential for confusion here, when modelling the Apollo-Saturn space vehicle, because different sources use different coordinates; and many diagrams, even those prepared by NASA, do not reflect the final reality.
In Part 2, I write about what happens to all those XYZ axes once the vehicles start moving around.
* I suspect I’m not the first person to notice that the S-IVB aft interstage chequer can be interpreted as sequential two-digit binary numbers, with black signifying zero and white representing one. Reading the least significant digit in the “low” positions, we have 00 in the A quadrant, 01 in the B quadrant, 10 in C and 11 in D—corresponding to 0, 1, 2, 3 in decimal. (I doubt if it actually means anything, but it’s a useful aide-memoire. Well, if you have a particular kind of memory, I suppose.)
The design and mission plan for this spacecraft were outlined in three articles written for Collier’s magazine, published in the issues of 18 and 25 October 1952, and these were my guides when building the kit. They’re available on-line, republished in Horizons, the newsletter of the American Institute of Aeronautics and Astronautics, Houston Section. The first two articles, by Wernher von Braun and Willy Ley, were reproduced in the Horizons issue for September/October 2012 (47MB pdf); the third, by Fred Whipple and Wernher von Braun, appeared in November/December 2012 (49MB pdf). In fact, the Horizons issues from July/August 2012 to September/October 2013 all reproduce classic Collier’s articles on the theme “Man Will Conquer Space Soon!”
The first thing to say is that this is a lovely kit—the parts fit together like a dream. And it arrives beautifully packed, with delicate pieces wrapped in foam. It’s also complicated, with some parts actually threading through other parts, and a few opportunities to mis-assemble if you don’t pay careful attention to the instructions and examine the pieces carefully before you commit to gluing. Parts are supplied for the crewed version or the cargo version.
I added a few details from ParaGrafix’s photoetch detail set, and some decals left over from previous projects. I ignored Pegasus’s painting guide. This follows Chesley Bonestell’s illustrations for the Collier’s articles, with fuel and oxidizer tanks tinted in shades of red, yellow and blue—you can see the effect in the box art at the head of this post. The colours seem to be lifted from a colour-coded diagram in Collier’s, showing the function of each set of tanks, and I couldn’t see a reason for them to be colour-coded in “real life”, so I went for plain white tanks instead.
I also needed to do a little modification. The big, outer, spherical tanks, prominently visible in the box art, didn’t actually make it to the moon. They were used to accelerate the ship out of Earth orbit, where it had been assembled, and were then discarded during the trans-lunar coast. So the ship actually landed in a slightly stripped-down configuration, as illustrated by Bonestell’s cover illustration for Collier’s.
Until the landing approach, the legs were stowed out of the way of the rocket blast—the outer legs folded upwards, and the telescopic central leg (which doubled as a landing sensor and shock absorber) drawn back between the rocket nozzles. The outer kit legs look as if they could be assembled in the folded-back position (though I didn’t try it), and it would require only minor surgery to model the central leg in the retracted position—so there’s the potential to configure this model into “Earth departure” mode with the large tanks in place. But I elected to reproduce the appearance shortly after landing, so I needed to remove the large tanks and then add a little scratch-built detail to the stumps of the support structure.
First up, I drilled out the portholes in the crew compartment, and added ParaGrafix detailing. Here’s a comparison of the upper half in its original state and the lower half with its modifications completed:
Then there was a tedious and repetitive period spent assembling and painting the various subcomponents of the spacecraft:
To get the eighteen central engines aligned with each other, I used slow-drying epoxy glue, so that I could tweak them around once they were in place:
Getting to the next stage of assembly requires the horizontal support structures to be slid on to eight vertical rods, while locating the various tanks between. There’s potential for confusion with the relative placement of long and short rods; and note that the shorter rods, which bear the small spherical helium tanks, have a definite right way and wrong way up.
Since I was planning to omit the big departure tanks, I needed to modify the support structures, guided by a diagram from one of the Collier’s articles which shows the plane of separation when the tanks were discarded:
First I needed to remove most of the external framework:
And then chop through the horizontal support frames and add a few bits of styrene to close off the open ends:
The upper end of the framework will support a couple of cranes which are included in the kit but are effectively undeployable until the departure tanks are discarded. The only way for the crew to reach the ground from their habitat sphere, 40-odd metres above the ground, is to descend using these cranes. The ParaGrafix detail set includes a couple of little elevator cages and some crane hooks.
To populate my elevator cage and add some indication of scale to the model overall, I wanted to add some astronaut figures. Tamiya produce a set of 1/350 crew figures for ship models, and I modified a few of these to look a bit more like astronauts by adding some strip styrene for backpacks and blobs of glue for helmets:
Here’s the final product, with a pair of crew members descending to the ground while others look on from the airlock “balcony” of the crew sphere and from the engine platform.
The outer banks of engines can be vectored in a single plane on the model, as was intended for attitude control in the real thing:
Finally, I’ve put together a couple of size comparisons to show what a monstrous thing this spacecraft would have been. Firstly, compared to the real Lunar Module:
And with the Statue of Liberty:
Now that would really have kicked up some dust when it landed.
This is the final post of my three-year project to assemble Revell’s 1/96-scale Saturn V model kit. It’s intended to provide a few views of the completed model, and to act as a sort of index to the various sections of the stage-by-stage build log I wrote as I went along.
The kit is fundamentally flawed because it was based on the original SA-500F Facilities Integration Vehicle, a test version of the Saturn V which never flew. (Any Apollo buff can tell that, immediately, from the paint pattern featured on the box art.) The sad thing is that Revell have never revised the kit, despite reissuing it a regular intervals, including this year’s 50th anniversary of the first moon landing. So the kit includes parts, decals and painting instructions that are inaccurate for any of the Apollo flights, because based on an early test article. It also includes things that are just plain inaccurate—wrongly placed and wrongly sized parts, and incorrect alignments of each stage with its neighbours.
To help me understand and try to fix these problems, I used David Weeks’s 1/48 Saturn V drawing sets, available from RealSpace Models. At exactly twice the scale of the kit, they were a real boon to confirm the location and orientation of various details.
First, here’s a four-quadrant view of the completed model, which depicts AS-506, the launch vehicle and spacecraft for the Apollo 11 mission:
And the upper section, in isolation:
There now follows a stage-by-stage description, from the top down, with links to the relevant parts of the build log.
The kit provides an early Block I Command/Service Module, whereas all manned flights used Block II CSMs. This is the resin replacement Block II from RealSpace. Kit parts are used for the Service Module’s Reaction Control System thruster blocks and S-band antenna. Some additional details were added from the New Ware set. RealSpace’s scimitar antennae on the Service Module were poorly moulded, and were removed and replaced with New Ware’s photo-etch parts. Bare-Metal Foil for the finish on the Command Module and aft Service Module heatshield. Some detailing with styrene sheet on the SM aft bulkhead. Decals from Space Model Systems appropriate for CSM-107, the Apollo 11 spacecraft.
The kit lacks a Boost Protective Cover for the Command Module—this is the vacu-formed part that comes with the RealSpace Block II Command/Service Module. I punched a couple of holes in it to represent the two windows over the central and commander’s (left) window of the Command Module. I added the kit Launch Escape System tower, detailed with some styrene rod to simulate structural ribbing and wiring harnesses.
This is the Spacecraft/Lunar Module Adapter (SLA) which housed the Lunar Module and supported the CSM. The kit provides an upper and lower section. The upper section contains an unrealistic window, to allow viewing of the Lunar Module in situ. The lower SLA is moulded in one piece with the Instrument Unit, in reality a separate section of the launch vehicle. I filled and painted over the SLA window, and detailed the structure with New Ware parts and styrene strips. I found it was possible to leave the upper part detachable from the lower section, so that the Lunar Module could be displayed in a realistic position on top of the Instrument Unit and S-IVB stage. I also scribed out an umbilical connection port, and corrected an error in New Ware’s decals—the black -Y axis marker provided for the Instrument Unit should be +Y. The moulded support for the kit CSM was removed, since it was positioned wrongly for the RealSpace CSM.
The alignment between the kit SLA and S-IVB stage is wrong, and requires correction—see build log for details. The kit parts include a printed styrene sheet to be rolled to form the central tank structure. This is marked USA, which is inappropriate for manned missions—I turned it inside-out and painted it to match the rest of stage. The fore and aft skirts needed extensive detailing from New Ware, and the service tunnel was replaced.
The kit provides a single part for the S-IVB aft interstage. The alignment between this part and the S-IVB stage is wrong, and needs to be corrected—see the build log for details. Instead of using New Ware’s replacement retro rocket fairings, I added simulated fairing covers to the kit part using epoxy. I also scribed a personnel access hatch, using David Weeks’s drawings for guidance. The chequered sway targets I painted are too large, but this is deliberate—when sized correctly they could not be made to look square, because of the oversize stringers of the kit parts.
The S-II stage is wrongly aligned with the S-IVB aft interstage—see build log for details of the correction required.
This stage is very poorly depicted by the kit parts. Fairings are missing or wrongly positioned, and need to be replaced with New Ware parts. Attachment points for the kit parts need to be removed and the stringers restored. Stringers extend too far on both the fore and aft skirts, and need to be trimmed back. I added an additional insulation layer to the fore skirt using styrene sheet. Several other areas need to be cleared of stringers to allow the addition of New Ware umbilical connectors and hatches.
The liquid oxygen vent pipes are wrongly positioned, and need to be moved. I also corrected the number and position of the gores on the forward tank dome so that the vent pipes could be properly placed in the correct position. New Ware provides a resin aft heatshield—the support structure was scratch-built using 0.5mm brass rod. The kit’s aft thrust structure is extremely inaccurate, and required considerable modification and detailing with styrene rod before adding resin instrument packages from New Ware. Again, I turned the kit’s printed styrene sheet inside out so that I could produce a uniform paint job, and then mark up with decals from New Ware.
The kit S-II aft interstage comes with eight ullage motors. These were reduced to four on the Apollo 11 launch vehicle, and were later omitted entirely. The attachment points for the kit parts therefore need to be removed and the stringers restored. The kit motor fairings are too small and need to be replaced with New Ware parts. The S-II fairings extended on to the aft interstage—all the New Ware resin fairings need to be divided at an appropriate level, with their trailing parts added to the interstage and aligned. New Ware provides a photo-etch personnel access hatch.
The white flight-separation junctions, above and below the interstage, were added using 0.5mm x 1.5mm styrene strip, wrapped around the locating flanges at the base of the S-II stage and the interstage.
The S-IC stage is wrongly orientated relative to the S-II. I corrected this at the junction between the S-II aft interstage and the S-IC—see build log for details.
The entire aft end of the S-IC stage needs to be remodelled, because of inaccuracies in the heatshield and engines. The F-1 engines were covered with batted insulation, but the kit parts are bare. I used RealSpace’s resin replacements, with Bare-Metal Foil detailing and some scratch-building to reproduce the appearance of the real engines. The kit heatshield is surround by air scoops, most of which were removed in S-IC stages that actually flew—New Ware provides resin replacement for the heatshield, engine fairings and fins, and photo-etch parts for the remaining air scoops on either side of the engine fairings. The New Ware heatshield is poorly detailed—I printed a custom decal sheet to depict rivets and other details in this area. I also scratch-built lunate heatshields for the engine fairings—neither Revell nor New Ware provide appropriately shaped parts.
Slots must be cut in the kit’s aft skirt to accommodate resin hold-down posts from New Ware. The kit service tunnels are the wrong shape and size, and New Ware provides photo-etch parts that can be applied to 7mm half-round rod to produce a more realistic result. Again, I turned the kit’s printed styrene sheets inside out, so that I could achieve a uniform paint job, and then apply New Ware’s decals. And again, stringers need to be removed in several areas to allow the addition of multiple umbilical connections and access hatches from New Ware.
NB: I failed to notice, until it was too late, that this stage is almost an inch too long for its scale size, with most of the extra length being in the forward tank and intertank skirt. This means New Ware’s service tunnels appear too short on the completed model.
The Lunar Module provided with the kit is wrongly shaped in several respects. I added some scratch-built detailing, painted the thermal panels and adding foil in appropriate shades for Apollo 11’s LM-5, and blocked off the hole in the access tunnel with styrene sheet. I also revised the tank support strut on the left front of the ascent stage—this is modelled as a flange in the kit part, which was removed and replaced with styrene rod. A lot more detail (plume deflectors, aerials and a docking target) could easily be added but I decided against it on the grounds that the LM would be invisible in the assembled model, and would be easily damaged on disassembly.
After completing the entire Saturn V stack, top to bottom, I had one small additional component to complete—the Lunar Module. This sat invisibly inside the Spacecraft/Lunar Module Adapter during launch and translunar injection, and was revealed only when the SLA panels were discarded during the lunar coast phase.
The LM that comes with the kit is incorrect in many details, and would need a complete rebuild or a resin replacement to fix. I contented myself with a few tweaks—adding some detail using pieces of styrene, filling the gaping hole of the docking port, and revising the depiction of the external strut that helped support the Aerozine-50 fuel tank on the left side of the ascent stage. The kit represents this last structure as a flange, which I removed and replaced with an appropriate section of rod. (The striking asymmetry of the LM in front elevation, including the presence of a support strut on the left but not on the right, is due to the different densities of the Aerozine-50 fuel and the nitrogen tetroxide oxidizer—to balance the structure around the thrust axis of the ascent engine, the heavier nitrogen tetroxide tank had to be kept close inboard on the right, while the lighter Aerozine tank was in an extended position on the left.)
After a lot of filling and sanding to patch together the two parts of the ascent stage, I painted the various panels with the peculiarly complicated pattern of different insulation colours specific to the LM5 of Apollo 11. The dark gold Kapton film on the underside of the ascent module was simulated with gold Bare-Metal Foil. I mixed up Tamiya’s Flat Aluminium, Yellow-Green and Buff to produce an approximation to the strange beige shade used for some of the LM’s panelling—it looks a bit too green in direct sunlight, unfortunately. And I used Tamiya’s Metallic Grey with a hint of Gold Leaf for the thruster quadrants.
The descent stage was painted black, and then patterned with silver foil and two shades of gold—Bare-Metal for the silver and dark gold Kapton, and some pale gold foil from a chocolate bar wrapper, stockpiled years ago when chocolate bars still came wrapped in foil. And although they don’t seem to be mentioned in the kit instructions, Revell does provide decals for the descent stages markings—an American flag and a UNITED STATES label, the second of which is distinctly oversized.
I should note at this point that the supporting struts for the lander’s legs are in the wrong position in these photographs—the locating lugs on the top of the lower (gold) V-struts needs to be positioned inside the apex of the upper (black) V-struts. This isn’t remotely obvious from the kit assembly instructions, and the kit parts themselves are reluctant to assume this position, but the LM will not fit into its correct location in the lower SLA unless the struts are assembled in this way.
Here’s what it looks like, properly stowed on top of the S-IVB stage—this is the view the astronauts would have had as they manoeuvred the Apollo CSM to dock with and extract the LM, during the lunar transfer coast.
And here it is with its legs folded for SLA stowage. (I tried to cover the foot-pads with appropriate dark gold foil, but couldn’t get a good result, so eventually used gold paint instead.)
And that was the final part of my long Saturn V project—three years from start to finish. Although I’m posting this after the 50th anniversary of the Apollo 11 landing has come and gone, I actually finished work just after midnight on 1st July 2019, a couple of weeks before the Apollo 11 anniversary—closer to the wire than I imagined I would be, three years ago, but still on time.
In my next (and last) post on this topic, I’ll show you what the whole thing looks like, with all the stages stacked.
Last time, I described how I needed to extensively modify the front and back ends of the Revell S-IC stage, using resin parts from RealSpace and New Ware, combined with some custom decals and a little scratch building.
Next, I needed to assemble the component parts of the stage—the fore and aft skirts, the intertank ring, and two styrene sheets that needed to wrapped into cylinders to represent the fuel and oxygen tanks.
As usual, I turned the styrene sheets inside out, so I could prime and paint the stage in a uniform pattern of black and white. (New Ware provides decals for the USA markings and the American flags.) Also visible in the picture above are the parts for the two long service tunnels that carried wiring up the outside of the tanks. The kit parts are undetailed and oversized, and New Ware’s solution to this is to provide a set of photoetch parts, ribbed to reflect the real surface of the service tunnels. These are supposed to be wrapped around the kit parts, and excess plastic pared away. The kit parts don’t really produce the right shape, unfortunately—the original tunnels were pretty close to being hemicylindrical. So I wrapped New Ware’s photoetch around lengths of 7mm half-round rod from Maquett instead, which produced a fairly nice result.
At this point, I noticed that New Ware’s tunnels were a little shorter than the kit parts. I checked against David Weeks’s Saturn V scale drawings and found that New Ware was pretty close to the correct length, and thought no more about it. (In retrospect, I should have thought more about it.)
So I wrapped the styrene, assembled the stage … and discovered that the service tunnels didn’t span as far as they should. I could have one end of the tunnel correctly located, but the other end wouldn’t reach far enough on to the skirt at the opposite end of the stage. More measuring ensued, and it turned out that Revell’s S-IC stage is almost an inch too long for the correct scale, with most of the excess length in the forward tank and the intertank. Well, sigh—they finally caught me out. I couldn’t see a good way to disassemble the pieces and trim them, so I accepted the inevitable and positioned the tunnels so that they leave a larger chunk of forward skirt exposed than they should do.
The engine fairings I kept separate, and painted in their final pattern of white, black and metallic. They were going to have to go on after I’d added the engine and firewall assembly I completed last time—the structural braces inside the engine fairings meant that each fairing assembly would need to be slid on sideways once its corresponding fairing firewall was in place.
So I primed and painted the cylindrical stage, leaving the final demarcation line between black and white on the aft tank to be completed once the fairings were in place. Then the firewall and engines were put in place, double-checking the correct orientation of the central engine. Then the fairings, then the finalization of the black stripes on the aft structure.
By this time, the whole thing was beginning to take up a lot of room on the workbench. Here it is, waiting for a coat of gloss and the New Ware decal set:
Positioning the American flags on the overlong forward tank needed a bit of calculation to make sure they were positioned in the correct proportion between the top and bottom margins, rather than working from the original measurements.
Finally, before the last coat of varnish, I added the delicate telemetry antennae to the forward skirt. (I knew that, if I added them any earlier, I would knock them off while preoccupied with decal positioning.)
And that was that. The literal final stage of this project:
Except … there’s one more small component to build before the project is complete. That’s what I’ll post about next time.
Addendum: I recently had an enquiry about my placement of the yellow drain labels at the top end of the aft tank. There are eight of these, placed just below the intertank section, at the top of each black and white stripe. They’re often depicted as being centred on the stripes (for instance, in the New Ware decal guide), but that doesn’t actually seem to be the case, at least in the S-IC-6 of Apollo 11. Looking at footage of the real launch vehicle from Apollo 11: Men On The Moon, by Spacecraft Films, I noticed that the labels were a little displaced from the centre line. Here’s a screen-grab to show the real positions, which I reproduced on the model:
Having completed the S-II Aft Interstage for my previous post on this build log, I’ve now progressed to the Big Beast of the S-IC.
This stage is composed of Revell’s usual combination of moulded cylinders for the skirts and intertank, and printed styrene sheets to be rolled into cylinders for the tank sections. The stage also has two service tunnels running along its length, each one provided in two sections in the kit:
As with previous stages, my plan was to turn the printed sheets inside-out, paint them white to match the other structures, and then detail them using the decals provided in the detail set by New Ware. The kit service tunnels are both too long and too large, so need to be replaced—I’ll come to that in my next post.
For this post, I’m going to describe a small modification to the forward skirt, a rebuild to the aft skirt, and a wide-ranging replacement of the kit’s engines, fairings and heatshield.
As usual for this kit, the S-IC needs to be rotated to bring it into correct alignment with the rest of the stack. So the locating lugs on the forward skirt need to be moved. This is complicated by the fact that I have previously rotated the aft part of the S-II stage through ninety degrees so as to be able to conceal an unrealistic kit feature. Not having undone that rotation when I modified the S-II Aft Interstage (because that kit part is rotationally symmetrical), I need to reverse that rotation now. A corrective quarter turn would amount to moving the locating lugs 3⅜″ clockwise around the rim, looking down. Instead, judging from the position of the S-IC service tunnels, I found I need only three-and-a-sixteenth. (So it seems to me that, if you build this kit without rotating the aft part of the S-II, you’ll need to move the S-IC locating lugs five-sixteenths of an inch anticlockwise to fix the stage alignment. But please check my working.)
As usual, the colours of the skirt interior and LOX dome are hard to ascertain. I used zinc chromate yellow-green for the tank on this stage, which matches the colour photos I’ve seen of the stage being assembled, as well as the apparent colour visible in the familiar footage of Apollo 4 staging.
At the other end of the stage, the big problem with the fairings and heatshield provided in the model kit is that they are rimmed with multiple air scoops, designed to drive cooling air across the heatshield between the engines and the fuel tank. These featured in early designs (on which the kit was based), but on operational Saturn V launch vehicles the scoops had largely been removed, leaving only a pair at either side of each engine fairing. So both need to be replaced with much plainer resin versions from New Ware.
The kit engines also need to be replaced. Revell provides bare F-1 engine bells of the kind seen on the small number of Saturn V vehicles that are on display. But in reality, the F-1 engines on operational launch vehicles were swathed in external insulation called “batting”, to protect the engine bells from hot gases billowing back from the rocket exhaust. It looked like this view of a test item:
The batting consisted of both generic pads applied to the bell, and shaped sections which surrounded more complex structures. As the photograph of the real thing shows, there was a slight difference in the reflective properties of these two kinds of batting. I aimed to reproduce this by applying chrome-finish paint to the resin, and then adding bright chrome Bare-Metal Foil detail.
RealSpace’s resin engines are adequately shaped to locate them accurately on the kit heatshield. And New Ware’s resin heatshield is adequately shaped to locate the kit engines correctly. But the two detail kits don’t have enough locating studs to align them precisely with each other. So I sawed the locating studs off the kit engines, and cemented them to the resin parts, ready to engage with the holes in New Ware’s heatshield; and I drilled out the gimbal mounts on the resin heatshield, and added short sections of brass rod to engage with the sockets on RealSpace’s engines.
Then I needed to attach the gimbal actuators to the engines. In reality, these “fueldraulic” pistons steered the outer engines, and were supported on structures concealed inside the engine fairings. Each outer engine had two gimbal actuators, attached to its base by an open pyramidal outrigger. The kit provides each actuator and its engine outrigger as a single, poorly detailed part.
I used the kit heatshield as a gig to get the correct relative positions of each resin engine and its pair of actuators. Then I filled the open pyramid of each outrigger with clear glue, allowing the glue’s surface tension to gather it into a pyramidal tent-like structure—that was my way of reproducing the appearance of the real engine outriggers, which were wrapped in foil batting along with the rest of the engine.
After painting and the application of foil detail, here’s what the engines looked like:
You can see that the centre engine sports a couple of vertical rods in place of gimbal actuators. This engine was not steerable, but still had outriggers attached, which were supported by rods attached to the heatshield. I scratch-built outriggers and rods for this engine, since the kit neglects that detail.
The New Ware heatshield is light on detail, providing only the outlines of the various tiles. In reality, the heatshield was dotted with rivets and other details, which you can see in this view of the Apollo 11 S-IC:
Guided by this photo, and John Duncan’s excellent reference photos of the heatshield of the S-IC displayed at the Kennedy Space Center, I drew up and printed a set of custom decals, which I applied, tile by tile, to New Ware’s resin part.
The next problem was the subsidiary heatshields positioned within each engine fairing. Both Revell and New Ware provide simple rectangles, supported at their outer corners by the base of the gimbal actuators. These certainly match the appearance in the Apollo 11 photo, above. But notice how many panels have been removed in the Apollo 11 view—engineers were gaining access to the interior of the Saturn V until late in the pre-launch period. So in fact, the whole interior of each engine fairing was eventually blocked off by a lunate heatshield built up of several panels—the rectangle in the Apollo 11 view is only the central part of a larger structure, as shown here:
So I scratch-built replacement fairing heatshields using styrene sheet.
A little experimentation with paper revealed that these needed to be cut from discs 22mm in radius, if they were to fit New Ware’s replacement fairings at heatshield level. (In fact, they should have been slightly elliptical, since the fairing heatshields were tilted a little from the horizontal.) These little lunes then got their own custom decals, reproducing what I could see of the panelling in various views of the JSC Saturn V.
Finally, the whole lot could be assembled:
The Revell aft skirt also needed to be seriously modified, since it lacks hold-down posts. These were important components of the real launch vehicle, since they supported the entire weight of the Saturn V on the launch-pad, and at launch engaged with hold-down arms which prevented the Saturn V taking off until full engine thrust was achieved.
New Ware provides four resin parts, each of which requires a large, shaped slot to be fashioned to accommodate it. Starting with a series of hand-drilled holes, I expanded and shaped each slot before fitting the hold-down and epoxying it in place, only moving on to the next slot once the glue was dry.
Finally, a dry assembly to ensure that everything fitted together. Notice the internal fairing support struts, which are photo-etched parts from New Ware.
Having completed the S-II stage, I’ve worked my way down the stack as far as the S-II aft interstage—a ring structure interposed between the first and second stages to provide clearance between the S-II’s rocket engines above and the dome of the S-IC’s liquid oxygen tank below. We can see it being dropped astern in this video taken from the second stage of Apollo 4: Also briefly visible in that video are the ullage rockets on the aft interstage, which were fired to shove the S-II forward just before its own engines fired. The whole stack was in free-fall between the shutdown of the first stage motors and the firing of the second stage engines, and there was concern that liquid hydrogen and oxygen would float around in the S-II’s tanks during this time, allowing gas bubbles to get into the mixture when the S-II engines fired. So the ullage rockets gave a little shove to the S-II, settling its fuel and oxidizer to the bottom of their tanks, next to the drainage piping, before the S-II engines were fired up. (Ullage is a nice old word originally referring to the air-space within a cask or bottle of wine. By extension, the unfilled volume in a rocket’s tanks is called ullage, and ullage rockets are used to make sure the ullage moves to the top, and the contents to the bottom.)
It turned out the S-II didn’t really need this precaution, and the number of ullage rockets on its aft interstage was reduced over time—from the eight visible on the Apollo 4 video, to four by the time of the Apollo 11 launch, and the last few Saturn V launches had no ullage motors at all on this stage.
So that’s the first problem with the Revell kit representation of this interstage—it has eight attachment points for ullage motors, and I only need four for my Apollo 11 launch vehicle. The second problem is that the kit parts for the ullage motors are the wrong size and shape—but I have New Ware resin replacements to deal with that. And the third problem is (predictably enough) that the attachment points are in the wrong places—Revell sites the eight ullage motors exactly on the principal axes of the Saturn V, whereas they were all displaced about 16 inches anticlockwise from those axes (looking down).
So all these mounting points have to go:
It’s a slightly harder job than disposing of the similarly misplaced mounting points on the aft skirt of the S-II, because these are big moulded structures that partially overlap the stringers on either side. So I first had to trim them level with the stringers, and then apply Dymo Tape to guide my razor saw and preserve the remaining stringer structure.
Then I used a 2mm chisel to remove all the excess plastic.
The other thing I needed to do was to mount the lower ends of the various fairings that I’d applied to the S-II. Many of these fairings extended across the flight separation line between the S-II and the aft interstage, and their lower ends were discarded along with the aft interstage (you can glimpse them in the Apollo 4 video, above). So I’d had to chop the ends off the New Ware resin parts when I mounted the fairings on the S-II stage. All these ends went into a pot, individually labelled, and now I was able to fit the interstage to the S-II and reunite all the severed parts (after chiseling away small parts of the stringers to make room for their attachment). There was also a personnel access hatch to be added, provided as a photoetch part by New Ware.
After priming, the final result looked like this:
I attached the interstage to the rear of the S-II again at this point, so that I could ensure continuity of the black stripes which begin on the S-II and extend across the interstage to the forward skirt of the S-IC stage. I got all the masking in the correct place, and then separated the interstage again for painting.
The interior colour of the Apollo 11 interstage is another source of doubt. The only colour images I can find come from early Apollo missions. Although the interior looks yellow (or even pink) in the interstage jettison videos of Apollo 4 and Apollo 6, it’s being subjected to the rocket blast of the S-II’s engines in these images. But there’s a clear view of Apollo 6’s aft interstage during the stacking process on the ground, which shows its interior with a metallic finish.
So that’s what I went with.
I also added a flight-separation junction to the bottom edge of the interstage, using 0.5mm x 1.5mm styrene strip, which you can see in this view.
The lines along which the interstage separated from the S-IC stage below, and the S-II above, were slightly raised ridges, painted white, which provided clear visual lines of demarcation traversing the black stripes, even when the rocket was viewed from a distance:
My original plan had been to add styrene to the top and bottom of the interstage, but it became evident it would be easier and more secure to attach the upper flight separation line to the flanges on the base of the S-II. Here’s the result when the two are stacked together, which I think simulates the appearance of the real thing fairly well:
So now it’s on to the first (and for me, final) stage.