The Apollo Technical Liaison Group for Structures and Materials discussed at STG the preparation of material for the Apollo spacecraft specification. It decided that most of the items proposed for its study could not be specified at that time and also that many of the items did not fall within the structures and materials area. A number of general areas of concern were added to the work plan: heat protection, meteoroid protection, radiation effects, and vibration and acoustics.
Three major changes were made by NAA in the Apollo space-suit circuit:
MSC reported that meteoroid tests and ballistic ranges had been established at the Ames Research Center, Langley Research Center, and NAA. These facilities could achieve only about one half of the expected velocity of 75,000 feet per second for the critical-sized meteoroid. A measured improvement in the capability to predict penetration would come from a test program being negotiated by NAA with General Motors Corporation, whose facility was capable of achieving particle velocities of 75,000 feet per second.
The North American Apollo impact test facility at Downey, Calif., was completed. This facility consisted mainly of a large pool with overhead framework and mechanisms for hydrodynamic drop tests of the CM. Testing at the facility began with the drop of boilerplate 3 on March 11.
MSC accepted the final items of a $237,000 vibration test system from the LTV Electronics Division to be used in testing spacecraft parts.
On this same day, MSC awarded a $183,152 contract to Wyle Laboratories to construct a high-intensity acoustic facility, also for testing spacecraft parts. The facility would generate noise that might be encountered in space flight.
MSC reviewed a North American proposal for adding an active thermal control system to the SM to maintain satisfactory temperatures in the propulsion and reaction control engines. The company's scheme involved two water-glycol heat transport loops with appropriate nuclear heaters and radiators. During December, MSC directed North American to begin preliminary design of a system for earth orbit only. Approval for spacecraft intended for lunar missions was deferred pending a comprehensive review of requirements.
Because they were unable to find a satisfactory means of plating the magnesium castings for the CM data storage equipment (to fulfil the one percent salt spray requirement), Collins Radio Company and the Leach Corporation were forced to use aluminum as an alternative. This change would increase the weight of the structure by about 2.3 kg (5 lbs) and, perhaps even more significant, could produce flutter when the recorder was subjected to vibration tests. These potential problems would be pursued when a finished aluminum casting was available.
North American conferred with representatives from Shell Chemical Company, Narmco, Epoxylite, and Ablestick on the problems of bonding the secondary structure to the CM. They agreed on improved methods of curing and clamping to strengthen the bond and prevent peeling.
The resident Apollo office at North American discussed the company's tooling concepts for the Block II spacecraft with the chief of Marshall's Planning and Tool Engineering Division and the local Marshall representative. These reviewers agreed on the suitability of North American's basic approach. Though they recognized that the initial tooling cost would be high, they nonetheless felt that the total costs of manufacturing would not be appreciably affected. The substitution of mechanical for optical checking devices, it was agreed, would eliminate much of the "judgment factor" from the inspection process; mechanical checking also would assure uniformity of major components or subsystems.
NASA announced that Kennedy Space Center's Launch Complex 16, a Titan missile facility, would be converted into static test stands for Apollo spacecraft. This decision eliminated the need for such a facility originally planned on Merritt Island and, it was predicted, would cost little more than a fourth of the $7 million estimated for the new site.
MSC Structures and Mechanics Division presented their findings on the possibility of qualifying the spacecraft's thermal protection in a single mission. While one flight was adequate to prove the ablator's performance, the division asserted, it would not satisfy the requirements as defined in the specification.
During the flight of boilerplate (BP) 23, the Little Joe II's control system had coupled with the first lateral bending mode of the vehicle. To ensure against any recurrence of this problem on the forthcoming flight of BP-22, MSC asked North American to submit their latest figures on the stiffness of the spacecraft and its escape tower. These data would be used to compute the first bending mode of BP-22 and its launch vehicle.
North American conducted acoustic tests on the spacecraft's interior, using boilerplate (BP) 14. Noise levels generated by the spacecraft's equipment exceeded specifications. Prime culprits appeared to be the suit compressor and the cabin fans. North American engineers asserted, however, that the test vehicle itself, because of its sheet metal construction, compounded the problem. These tests with BP-14, they affirmed, were not representative of conditions in flight hardware. Data on communications inside the spacecraft were inconclusive and required further analysis, but the warning alarm was sufficiently loud to be heard by the crewmen.
North American reviewed nondestructive techniques for testing honeycomb structures. The principal method involved ultrasonic testing, but this approach was highly dependent upon equipment and procedure. At best, ultrasonic testing could do no more than indicate faulty bond areas, and these could be confirmed only through destructive tests. A number of promising nondestructive methods were being investigated, but thus far none was satisfactory. The danger in this situation was that, if design allowables had to be lowered to meet the results of strength distribution tests, the weight advantage of honeycomb construction might be lost.
The MSC Systems Engineering Division published revisions to Apollo Mission 204A objectives and mission requirements. The principal difference between the revised version and the Initial Mission Directive for Mission 204 was the expansion of the secondary propulsion system performance objective, the radiation survey meter objective, which was deleted, and the don/doff of the Block I pressure garment and thermal blanket objectives which had also been deleted.
North American and NASA officials conducted an engineering inspection on boilerplate 23A at White Sands Missile Range, New Mexico. The board approved four requests on minor structural changes; a fifth request, involving tolerances on the boost protective cover, was slated for further study.
ASPO Manager Joseph F. Shea concluded, after reviewing the boilerplate 22 mission, that all the test objectives would be met satisfactorily either in the flight of spacecraft 002 or in the ground qualification program. For that reason the boilerplate 22 flight would not be repeated.
Systems Engineering Division (SED) reported that, on the basis of data from SA-4, 8, and 9 flights, the thermal coating of the spacecraft suffered considerable damage. This degradation was caused by the S-IV retro motor and/or the tower jettison motor. SED advised that a thorough analysis was scheduled shortly at TRW to look into the entire area of thermal factors and the performance of ablative coating. However, North American refused to acknowledge the existence of any such thermal problem, SED said. The firm's "continued inactivity" was described as a "major obstacle" to solving the problem.
Because earth landing system qualification drop tests on boilerplate 6A and boilerplate 19 had failed to demonstrate that Block I recovery aids would not be damaged during landing, MSC notified North American that certain existing interim configuration recovery aid mockups must be replaced by actual hardware capable of fulfilling test requirements. The hardware included: two VHF antennas; one flashing light; one RF antenna, nondeployable; sea marker, swimmer umbilical, nondeployable. In addition, existing launch escape system tower leg bolts should be replaced by redesigned Block I tower bolts, including protective covers, to demonstrate that the redesigned bolts and covers did not degrade the performance of the earth landing system. North American was to reply with a total change plan by January 5, 1966.
As a result of joint efforts by the Resident ASPO and MSFC Resident Manufacturing Representative, a simulated forward bulkhead for the CM inner-crew compartment was fabricated by North American and sent to MSFC for use in developing a head for the magnetic hammer which would be compatible to the extremely thin skins used on the compartment. The need for the magnetic hammer arose from the "canning" and "wrinkles" found after welding on the forward bulkhead. A tryout for the magnetic hammer on the simulated bulkhead was scheduled the first week in January.
The NASA Western Support Office, Santa Monica, Calif., reported two accidents at North American plants, with no personal injuries:
Rolf Lanzkron and Owen Morris, Chiefs of MSC's CSM and LM Project Engineering Divisions, led a review of the 2TV-1 and LTA-8 (thermal vacuum test article and lunar module test article) thermal vacuum test programs at MSC. Chief concerns expressed during the review centered on the heavy concentration of testing during the summer of 1968, the need for simultaneous operation of test chambers A and B, and the lack of adequately trained chamber operations support personnel for dual testing. The review disclosed that maintenance of testing schedules for LTA-8 was most unlikely, even with a seven-day-a-week work schedule. (The central problem was the large number of open items that had to be cleared before start of the tests.)
In response to a letter from ASPO Manager George M. Low in late December 1967, seeking assurances that no potential stress corrosion problems existed in the CSM, Dale D. Myers, CSM Program Manager at North American Rockwell, reviewed the three instances where problems had been encountered during the CSM project and iterated the extensive efforts to ensure against such potential problems. Echoing much the same words as his counterpart at Grumman, Myers stated that "it is not possible to guarantee that no single instance of stress corrosion will ever occur" and that circumstances "could create a problem not anticipated." He concluded that his company's efforts in this direction had been "entirely adequate and beyond the requirements of the contract and good practice in this industry," and he seated his belief that additional efforts in this area would not produce measurable results.