Appendix 8

Block II vs. Block I Apollo Spacecraft;

Hardware, Changes, Tests

[From "Manned Space Flight Report: Block II Spacecraft" in House Committee on Science and Astronautics, Subcommittee on NASA Oversight, Investigation into Apollo 204 Accident: Hearings, 90th Cong., 1st sess, 3, no. 4, [sic]* May 10, 1967, 223-35.]

* should be: Hearings, 90th Cong., 1st sess, no. 3, Vol. 3, May 10, 1967, 223-35

Subsystems and Units Unchanged for Block II CSM

Launch escape system
Command module reaction control system
Service module reaction control system engine cluster
Fuel cell power plants and entry batteries
Cryogenic oxygen and hydrogen storage system
Sequential events control system
Emergency detection system
Spacecraft LM adapter
Atmosphere supply system
Primary equipment cooling loop
Waste management system
Crew couches
C-band radar transponder
Ordnance devices
Parachutes and recovery aids

New Subsystems and Units in Block II CSM

Docking system

Docking tunnel and probe

Umbilical and pressurization

Rendezvous radar transponder

Sequence controllers

LM docking and separation events

S-band antennas

Flush omnidirectional

High gain

Subsystems and Units Changed in Block II CSM

Structure:

Command module

Docking provisions, mechanism, and hatch

Extravehicular capability

CM/SM mechanical connection

Scientific airlock available

Service module

Propellant tanks

Empty bay

Internal rearrangement

Structural redesign

Radiator areas

RCS mounting panels

Propulsion:

Service module propulsion system

Mixture ratio

Thrust chamber

Gimbal actuator

Service module reaction control

Propellant capacity

Monomethylhydrazine fuel

Crew support:

Environmental control system

Redundant cooling loop

Radiator design and area

Spacesuit

Apollo suit

Extravehicular capability

Displays and controls

Panel structure

Electroluminescent lighting

Entry monitor system

Power and communication:

Electrical power system

Radiator area

Distribution bus added

Cable harnessing

Pyrotechnic initiator

Wire deadfacing at separation

Unified S-band

Primary mode for all communications

Repackaged

Simultaneous data and tape dump or TV

Electrical redundancy

Voice VHF

Redundant and duplex

Guidance and control:

Guidance and navigation

Digital autopilot

Computer repackaged

Electronics repackaged

Navigation base support

Stabilization and control system

Revised interface

Electronics repackaged

Redundant attitude display

Atmospheric entry and touchdown:

Heatshield

Redistributed ablative thickness

Truncated apex

Umbilical location

Flush antennas

Earth-landing system

Steel parachute risers

Parachute attach points

Repackaged

Crew Safety Systems

Launch escape system
Emergency detection system
Sequential events control system
Earth-landing system
Environmental control system
Reaction control system
Electrical power system
Command module heatshield
Structure system

Mission Success Systems

Spacecraft adapter
Waste management system
Guidance and control system
Stabilization and control system
Communications system
Displays and controls
Service propulsion system

Subsystems with Internal Redundancy

(Subsystem)	(Major function)
CM reaction control system	Attitude control Lift vector control
SM reaction control	Attitude control S-IVB/CSM separation CM/SM separation
Communications system	Navigation data Voice, telemetry, and tracking Recovery
Electrical power system	Electrical power
Environmental control system	Equipment cooling Cabin environmental control
Sequential events control system	Separation signals Earth-landing functions
Emergency detection system	Launch vehicle malfunction
Earth-landing system	Atmospheric descent Uprighting at impact

Backup System Capabilities for Earth-Orbital Flight

Subsystem	Major Function	Backup
Service propulsion system	Deorbit	SM-RCS; CM-RCS
Command module reaction control system	Attitude control	SM-RCS spinup before separation for ballistic reentry
Guidance and control system	Attitude, translation, and lift vector control Control of SPS burns	Stabilization and control system
Stabilization and control system	Backup attitude, translation, and SPS control	Manual

Flight Safety Systems Changed in Block II

Earth-landing system
Service module reaction control system
Electrical power system
Environmental control system
Command module heatshield
Structural system
Service propulsion system

Environmental Control System Changes for Block II before AS-204 Accident

New radiator design:
- Increased size.
- Selective stagnation control.
- Secondary loop tubes.
Secondary coolant loop:
- Additional pump.
- Redundant cold plate passages.
Repackage environmental control unit (ECU):
- Coolant pumps relocated external to ECU, repackaged, and capacity increased.
- Coolant reservoir located external to ECU.
- Redesigned suit heat exchanger.
LM pressurization capability.
Relocate postlanding ventilation valves.
Redesign steam duct.
Add rendezvous radar cold plates in SM.

Proposed ECS Changes for Block II after AS-204 Accident

Add armor plating to exposed solder joints.
Change soldered-aluminum oxygen lines to stainless steel.
Rapid cabin repressurization.
Improve accessibility of selected ECS controls.
Shields for plumbing lines.
Optional use of air in cabin during launch.
Emergency breathing masks.
Add quick disconnects to environmental control unit.
Replace selected materials.

Block I - Major Ground Test Programs

Test Article	Test	Purpose
CM BP-6A	Parachute drop-testing of boilerplate CM	Flight-qualify earth recovery system by series of aircraft drop tests
SM-001	SPS propulsion ground test	Demonstrate SPS performance (oxidizer-to-fuel ratio = 2), 2nd SPS-structure compatibility
SLA	Static structural test of spacecraft-LM adapter	Test SLA static structural load capability (ultimate)
CSM 004	Static and thermal structural ground test	CM static structural load test (ultimate) CSM static structural load test (ultimate) CM thermal structural load test (reentry design)
CSM 007	Varied spacecraft testing	CM and SM acoustic vibration environment test CM water-landing impact drop test Postlanding systems operational/crew compatibility tests (uprighting, postlanding ECS, postlanding communications)
CSM 008	Thermal vacuum test of complete systems spacecraft	Demonstration of structural, integrated subsystems and crew compatibility under thermal vacuum environment

White Sands Missile Range Flight Tests

Test Article	Test	Purpose
BP-6	Boilerplate - LES pad abort flight test	Demonstrate launch escape system's pad abort performance
BP-12	Boilerplate - LES transonic abort flight test	Demonstrate launch escape system's transonic abort performance
BP-23	Boilerplate - LES high-dynamic-pressure abort flight test	Demonstrate launch escape system's maximum-dynamic-pressure-region abort performance
BP-23A	Boilerplate - LES pad abort flight test	Demonstrate launch escape system's pad abort performance with Canard, BPC, and major sequencing changes
CSM 002	Spacecraft structure - SM boost environment and LES tumbling abort flight	Determine actual spacecraft SM's dynamic structural response to boost dynamic loads Demonstrate launch escape system's tumbling abort performance and plume-impingement-load capability of CSM

Block II - Major Ground-Test Programs

Test Article	Test	Purpose
BP-6B	Parachute drop-testing of boilerplate CM	Flight-qualify earth recovery system by series of aircraft drop tests
F-2A	Fixture for SPS testing	Evaluate performance effects on SPS engine of fuel and oxidizer mixture's ratio change from 2.0 to 1.6
180 degree SM segment	Acoustic test article (SM) testing	Quality SM structure and systems to launch and boost vibration environment
CM 28-1[sic]*	Static and dynamic structural testing	Evaluate water impact on CM structure Docket CM/LM interface static structural tests
CMS 2S-2	Static structural testing	Static-test CM and SM structures (ultimate)
CMS 2TV-1	Complete systems spacecraft thermal vacuum testing	Demonstrate structural, integrated subsystems, crew compatibility, and life support in thermal vacuum environment

*should be: CM 2S-1

Block II - Revisions of and Additions to Major Ground-Test Programs

Test Article	Test	Purpose
2TV-1	Complete spacecraft thermal vacuum	Qualify fire related changes
004A, 007A	Unified hatch qualification	Functionally qualify acoustic testing, postlanding testing
CSM	Acoustic vibration	Demonstrate functional and structural integrity of stacked CSM-SLA
Material	Materials evaluation	Continue evaluation of non- or low-flammable material
Boilerplate	Command module fire test	Evaluate fire propagation in flight-configuration CM interior
EMU articles	Extravehicular mobility unit qualification	Qualify Block II unit with materials change
ECU articles	Environmental control unit qualification	Qualify Block II unit with all required modifications