posted 05-01-2009 08:06 PM               

The two-block approach was seen as a way to get hardware flying as soon as possible.

NASA had decided on a "building block" approach to landing on the moon, with various mission types designated "A" through "G" (e.g., refer to Chariots for Apollo and then search for "Basic Missions"). These mission types included unmanned launch vehicle/spacecraft development missions and manned tests of the CSM in earth orbit. For these types of missions, docking-capable command modules were not required, and so a simpler design would suffice.

Early on, there were plans to fly several manned Block I flights, but by the time the flight of Apollo 1 drew near, schedule pressures had whittled that down to two or even just one Block I mission.

EVA wasn't a priority in the Block I missions. The Apollo spacesuits also came in Block I and Block II designs; the Apollo Block I suit was based on Project Gemini's non-EVA suit and was primarily intended for crew safety.

posted 05-04-2009 03:28 PM               

As such, in late 1963, changes were still occurring on a daily basis and NAA needed to start building capsules for the first flight tests planned for 1965 and 66. It would take 18 months to build an Apollo CSM. As such, a baseline configuration was needed so the workers on the floor could begin manufacturing standardized parts for the first capsules. So the design was frozen as the block 1 while work continued on what became the block 2 capsules, which wouldn't be needed until late 1967/ early 68, meaning that design wouldn't need to be finalized until early to mid 1966 (after the first couple unmanned test flights had flown). It was known from early on that the Block 1 craft were too heavy to do a lunar flight (although there were some ideas drawn up to use a block 1 capsule for a Lunar flyby mission), but things didn't need to be refined as much for the test flights.

posted 04-12-2018 07:18 PM            

I'm curious about the external configuration of the Block 1 Command Modules, and how and when (and if) it changed. Specifically, the location of the VHF scimitar antenna and the CM/SM umbilical connection.

I recently visited the Fernbank Museum in Georgia to see the Apollo 6 Block 1 CM. Many Block 1 CM drawings show the two scimitar antenna at approx the +/-Z locations on the aft CM skirt. There were no scimitar antenna, or obvious mounting points, visible on the Apollo 6 CM. When did these antenna move from the CM to the SM, and were any Block 1 CMs ever constructed with said antenna? I have seen photos on the web that purport to be Block 1 CMs with the antenna but those seem to conflict with other photos and artifacts.

posted 04-22-2018 04:48 PM               

Regarding the scimitar antennas: A fair amount of documentation referred to these as "SCIN antennas" (noting that "the word 'SCIN' is an acronym for 'SCImitar' and 'Notch'" for their construction). The antennas themselves were inside fiberglass housings. The SCIN antenna under the crew entry hatch was called the "surviving SCIN antenna" and the one opposite the hatch was called the "non-surviving SCIN antenna" (presumably because it was on the side to the spacecraft exposed to higher reentry heating and was expected to be destroyed during reentry, although see an AS-202 photo below).

An undated Block I Apollo Spacecraft News Reference to which I had access (which was issued after Gemini 10 [18 July 1966] and apparently before AS-202 [25 August 1966]) has a diagram depicting the location of the two SCIN antennas but notes that they will be "relocated to SM for Block II."

It does appear that most or all Block I command modules built before the Apollo 1 fire had the +Z and -Z SCIN antennas.

S/C 002 (the first production Apollo spacecraft launched, on a Little Joe II, now residing at the Cradle of Aviation museum) is displayed with a SCIN antenna fairing under its hatch; the parachute prevented inspecting the back side of the spacecraft. However, a photo of the spacecraft being prepared for launch (photo at bottom right) shows the SCIN fairing. The Postlaunch Report for Apollo Mission A-004 (Spacecraft 002) has a diagram on page 5-99 (p. 166 in the PDF) depicting the antenna. Pages 5-174 and 5-183 (pp. 241 and 250 in the PDF) have low-quality photos showing the antenna fairing.

S/C 008, which was used for thermal vacuum tests, has several photos with showing its SCIN antenna fairings (the fairing under the crew entry hatch has a protective covering over it in many of the photos):

• S66-34205 (also note lack of simulated Block II umbilical)
  
• S66-34207
  
• S66-34211
  
• S66-34212
  
• S66-34213
  
• S66-34214 (also note lack of simulated Block II umbilical)
  
• S66-42570 (uncovered fairing visible below work platform toward right side of photo)

S/C 011, launched on AS-202, also had SCIN antennas:

• S66-50640 (red, at right)
  
• S66-50641 (visible under the three horizontal red dots in full-resolution version)
  
• S66-50642
  
• S66-50643 (again under the three red dots)
  
• S66-50644
  
• S66-49413 (not directly visible, but something at its location is causing the protective pad to deform and bulge
  
• S66-49247 (the charred remains of the "non-surviving" SCIN antenna are visible at right)

The S/C 011 pre-launch photos above show that the +Z SCIN antenna is located where the Block II umbilical would be located, and so it has no simulated Block II umbilical.

It would appear that S/C 012, Apollo 1, also had the antennas and lacked a simulated Block II umbilical. Apollo Operations Handbook: Command and Service Module (Spacecraft 012), dated 12 November 1966, has a diagram on p. 2.8-58 (p. 550 in the PDF) depicting the surviving and non-surviving SCIN antennas (the diagram also shows the notches in the scimitars). S67-15717 shows the SCIN antenna under the crew entry hatch.

An unidentified spacecraft (which looks a lot like S/C 012 in the previous photo) shows the +Z SCIN fairing, again located where a Block II umbilical would be located. Page 2.9-29/2.9-30 (p. 609 in the PDF) of the S/C 012 Operations Handbook shows only a Block I umbilical guillotine (i.e., no guillotine for a Block II umbilical).

It appears that the fire hastened the planned move of the scimitar antennas to the service module. The "Communications Subsystem Performance" section of the Apollo 4 Mission Report, on p. 5.13-2 (p. 275 in PDF), notes in that "The primary difference between Spacecraft 011 [AS-202] and Spacecraft 017 [Apollo 4] was in the antenna hardware configuration. Spacecraft 017 used four Block II S-band omnidirectional antennas flush mounted on the periphery of the aft heat shield and two Block II vhf/uhf scimitar antennas mounted on the service module."

(The remaining photo links in this post are via the Apollo Archive Apollo Image Gallery, either "Early Apollo" or "Saturn V." The Apollo Archive doesn't allow one to link directly to a photo's metadata.)

KSC-67P-208 claims to be a "top-to-bottom view of SA-501," but shows an atypical (in that it has no protective wrapping and has exaggerated panel lines) Block I type CSM with SCIN fairings. 67-HC-825, of Apollo 6, shows an Apollo spacecraft model in the background, which may be the spacecraft which was temporarily mated to SA-501.

67-HC-552 and KSC-67C-9604 are photos of Apollo 4 on the pad. If your browser shows you the full-sized photos, there will be no SCIN protuberances on the BPC and there will be no Block II umbilical fairing on the side of the spacecraft opposite the whiteroom (e.g., compare to KSC-71PC-69, of Apollo 14), but that there is a SCIN fairing on the service module. Recovery photo S67-49420 does not show a +Z SCIN fairing.

As with the AS-202 recovery photo above, a protective pad obscures the area under the hatch where the SCIN antenna would be, but unlike AS-202, Apollo 4 is not causing a bulge in the pad, indicating its lack of SCIN antenna.

68-HC-201 is an Apollo 6 launch photo. It's hard to tell whether or not there's a Block II style umbilical fairing just by looking at that photo, but it's obvious that there isn't one when comparing it to this Apollo 11 launch photo. The Apollo 6 photo also shows a SCIN antenna on the service module. Clicking the "banner" photo at the top of NASA's "50 Years Ago: The Second All-up Saturn 5 Test" page shows that the simulated Block II umbilical started off with all of its wires and tubing pre-severed and apparently painted over. (This would appear to be before the simulated wires were trimmed for the ablative panels.) Recovery photo S68-27161 shows no SCIN antenna under the hatch, and S68-27041 shows the lack of SCIN antenna near the simulated Block II umbilical.

So, as far as I can determine, the Block I spacecraft, up to and including Apollo 1/Spacecraft 012, had the two scimitar/notch antennas on the command module and lacked simulated Block II umbilicals. The two Block I command modules launched after the fire (Apollo 4 and Apollo 6, S/C 017 and S/C 020) relocated the SCIN antennas to the service module and had simulated Block II umbilicals, although the umbilicals on these spacecraft were not actually connected to the service module and did not have Block II style umbilical fairings.

posted 05-19-2018 08:51 PM            

Rather than consuming a lot of bandwith with embedded images, here is a link to an imgur folder of my Apollo 6 photos. In addition to closeups of the hatch area and the Block 1 style umbilical, there is also a photo of the simulated Block II umbilical connection.

The museum staff was also very accommodating of my photography efforts. They removed the plexiglas cover over the hatch and allowed me to photograph the interior thru the hatch opening. One interior photo shows the cable routing to the Block 1 umbilical connector.

imgur.com/a/rPfvS