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Aviation History
1961
1961 - 1558.PDF
662 FLIGHT, 26 October 1961 Take-off on October 11 of the NB-52 from Edwards AFB carrying a North American X-15 which after release zoomed to a height of 215,000ft (40 miles). In the subsequent 4g pull-out the port windscreen shattered, but the sections remained in the frame WEST COAST RESEARCH . . and Teflon. While the other samples showed obvious signs of heatdamage, the last-mentioned came through very well. Research scientist Dr Dean Chapman contributed what appearedto be a long and unrelated digression on tektites. Fascinating as the description of the glass morsels from space turned out. the audiencebegan to ponder upon the value of becoming tektite experts. It was not until the magic number 25.000 m.p.h.—tektite entry velocity—was given that the significance of the little glass objects was realized. The samples shown had been found in Western and CentralAustralia and belong to the British Museum. Most tektites enter the Earth's atmosphere as small glass spheres of about lindiameter, but burn down to slightly larger than a jacket button. Artificial tektites can be used as standards for comparison in theheat simulator. Jn this way, the heat-resistant properties of materials studied for use as ablative heat shields for 25,000 m.p.h.entry can be measured with some precision. Next on the list of briefings came "Research at SpacecraftSpeeds and Temperatures" in the hypersonic ballistic tunnel facility. Here the Vice-President was told of models of hypersoniccraft being fired through the instrumented test section of gun- barrel tubes. Speeds of up to 22,000 m.p.h. had been reached in thetubes, which when combined upstream with the hypersonic shock tubes produced relative velocities up to 30,000 m.p.h. Some timewas given to a discussion of meteorite problems in space, which were being studied in the tubes. Short film clips, taken at 1,400,000frames/min. showed the destructive effect of meteorites on vehicle structures (the film clips were reshot at one five-millionth of theshooting speed). Small glass spheres were fired into l/16in-thick double-walled aluminium-alloy structures, at velocities up to23,000 m.p.h. The audience was surprised to learn that such a structure is as effective, in stopping particle penetration, as a single0.5in sheet. The destructive effects of the particles entering a space- craft were measured on a third sheet of material behind the double-wall structure. It was discovered that when particles are fired at an angle of 45' and a velocity of 19,000 m.p.h. pulverization of theglass projectiles is complete, and small particles are spread over a relatively large area, compared with a velocity of 7,000 m.p.h.at which the glass clusters. Interestingly enough, damage to the third sheet is the same at the two widely separated speeds. Thechief of the hypervelocity ballistic range, Mr Thomas Canning, suggested that meteorite velocities ten times those under investiga-tion could be anticipated in space, and would somehow have to be explored. Our future space-travellers' vehicle was going to be eroded byions, bombarded by protons and its communications disturbed by solar flares. And other hazards were brought to the Vice-President'sattention by the chief of vehicle-environment, Dr Alfred Eggers. Ames is conducting extensive research with solar proton analysersand solar emission receivers. The facility has three ion accelera- tors, the most powerful working in the 50-200KV range. Explorer12 had shown that the low-energy proton particles, the most populous in space, existed in a density of one particle per cubiccentimetre. This result was obtained when the slit entrance to the satellite's proton analyser was turned away from the Sun during itsswoops from an apogee of 5,000 miles to a perigee of 200 miles. Solar flares on the Sun were described as "a great mystery" whichneeds to be cleared up by sending a satellite around the back of the Sun in order to correlate interference data with observations onEarth. A probe shot 1 /JOth of the distance towards the Sun (i.e., 9,000,000 miles) was held immediately possible. All theseradiation studies would benefit the design of Apollo, according to Dr Eggers. LBJ's tour of Ames was wound up with a brief description of Apolloguidance problems. This research is being conducted by the Mas- sachusetts Institute of Technology group which was responsible for the early work on Polaris guidance. But no comparison in com-plexity is reasonable between the Polaris and Apollo guidance systems, the latter being infinitely more complex. Desired terminalguidance accuracy to the Moon was described as being six miles to the Moon approach point. In the first system study the bestpossible manual optical inputs for correction inlo the mid-course guidance system computer were not accurate enough. Later, insome mysterious way, probability came to-the rescue of the com- puter inputs, and in a recent exercise landed Apollo within twomiles of the approach spot. Edwards Air Force Base Official greetings at the NASA FlightTest Center were made in the hangar before the X-15 which recently suffered 1,000 F over much of its structure. Here, by way of intro-duction, the Vice-President learned that the runway at Edwards is 15.000ft long, and lies in a flat, rock-hard dry lake 13 miles across.The runway, with overrun, had proved a blessing to a brakeless Douglas DC-8 a few days previously, and to a Boeing 720 landingwithout flaps the night before the visit. Neither aircraft had been scheduled to visit Edwards; passengers must consider trips toEdwards as undesirable as unscheduled visits to Cuba. Paul Bickle, NASA Director of Flight Research at Edwards,briefed the party on the research background to the X-15 and the role played by NASA. He announced the latest X-15 figures:height, held down to 70,000ft (design 250,000ft); heat, under fuse- lage 1.000F, wing LE 830 F (design l,200°F); speed, M5 (designM6). He added that after 41 flights the X-15 was capable of being a much broader research tool than was seen at the beginning of theprogramme, and that the military services as well as NASA looked to it for many inputs for use in their space vehicles. Advancedflight-control system study for spacefiight research would be started in two weeks, and an F-104 was already flying the reactioncontrol system to be used. Structural advances from X-15 study had proved illuminating to many designers. Advanced componentresearch had accelerated considerably because of the X-15 and the 1,5001b of instrumentation it carried. A programme of celestialphotography was planned from more than 100,000ft, using the X-15 as a camera stand, in which the Sun and planets would be seen withfar greater clarity and accuracy than from the ground. Smiling Joe Walker, NASA pilot, threw in a few facts of X-15life during a brief film: "heart and pulse rate go up at landing, probably because there are people watching . . . now operating Dr Donal B. Duncan (left), general operations mana- ger of Space Systems Operations at Ford's Aero- nutronic Division, and James D. burke, Ranger project manager at JPL, study an advanced model of the Ranger spacecraft and its lunar capsule
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