Feb 19 1975
From The Space Library
19 February-19 March; Hairline cracks were discovered in the holddown fittings on the fins of the Saturn IB launch vehicle scheduled to launch the Apollo spacecraft in the Apollo-Soyuz Test Project in July. After an earlier routine inspection at Michoud Assembly Facility had turned up one crack, a more detailed inspection at Kennedy Space Center 19 Feb. revealed 25-cm cracks on the fittings of two of the eight fins. A decision was made to replace the two fins. The cracks would not affect flight, but were in an area carrying the weight of the vehicle as it sat atop the mobile launcher. During a later inspection, cracks also were found in the remaining six fins, making it necessary to replace all eight.
Replacement work began 11 March. Engineers strengthened the cracked areas by placing compressive stresses in the surface of the material, by pneumatically pounding it with a small bundle of rods. Six of the fins were replaced by 15 March.
The spacecraft was placed atop the Saturn IB on 17 March and replacement of the remaining two fins was completed by 19 March. (KSC Release 27-75; NASA Release 75-50, 75-57; Marshall Star, 19 March 75)
The Air Force System Command's Materials Laboratory had successfully static-tested a full-scale F-15 aircraft wing constructed of advanced composite materials, AFSC announced. The wing had withstood a maximum load 45% greater than expected during actual flight, before giving way at the point where the titanium rear spur flange and upper skin were bolted together. The composite wing, 18% lighter than an all metal wing, was made of a brown epoxy thin honeycomb sandwich material reinforced with graphite-epoxy stiffeners. The ribs were graphite-epoxy and the spurs were metal. The wing, the largest aircraft wing ever built of advanced composite materials, was 4.9 m wide at the root chord and 1;5 m wide at the tip chord, and had a 4.3-m span.
The program had begun in May 1971 with an $82-million contract award to McDonnell Douglas Corp. for development of the wing, which was expected to reduce fuel requirements by increasing range, speed, and maneuverability. (AFSC Release OIP 021.75)
Despite the immediate need for aircraft noise-abatement regulations, little or nothing had been done, Sen. John V. Tunney (D- Calif.) said in a speech on the floor of the Senate. The Federal Aviation Administration was considering proposals to curb jet-fleet noise by retrofitting engine nacelles of JT-3D and JT-8D aircraft with sound-absorbing material. Delay had come in part from industry, which favored an alternate NASA refan program costing five times that of retrofit and not technologically feasible for several years. In addition, the NASA program could not quiet the JT-3D aircraft-the Boeing 707s and McDonnell Douglas DC- 8s-which made up the noisiest fourth of the nation's jet fleet. Sen. Tunney said that the potential benefits of the NASA program did not justify waiting until the technology was ready at a cost five times greater than retrofitting. If FAA was to prove responsible in the area of aircraft noise abatement, it could not "succumb to industry pressure against retrofit." A retrofit regulation should be put into final form at the first available opportunity. (CR, 19 Feb 75, S2160)
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