FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1959
1959 - 3470.PDF
FLIGHT, 25 December 1959 One of the many configurations studied is the slender delta. This example is being tunnel tested by the U.S. National Aeronautics and Space Administration, in an open-jet tunnel at the Langley laboratory 775 HYPERSONICS Vehicles Intended for Controlled Flight at 15,000 m.p.h. : Some British and American Suggestions EARLIER this year a Symposium on Hypersonic Flow wassponsored by the Colston Research Society, and held atthe University of Bristol. From the many papers there presented, we have chosen two for abstraction in order to providean outline of the type of craft which may become familiar within 20 years. The first paper was presented by H. Metcalfe of the G.W.aerodynamics department, Bristol Aircraft. He opened his paper by postulating generally accepted limits for sustained flight atabout 15 to 40 lb/sq ft wing loading and equilibrium skin tempera- tures of 1,000 to 1,200 deg K for steel airframes. In certain circum-stances, ablation, insulation, heat-sink or refrigeration techniques enable reasonably sustained flight to be achieved at higher skin-temperatures. Strategic ballistic missiles penetrate the equilibrium skin-temperature limit on re-entry. A range of low-altitude flightconditions is shown in Fig. 1. Fig. 1. Flight regimes for ballistic missiles Fig. 2. Flight regimes for skip and glide vehicles 500 10 15 VELOCITY (ft/sec x 1000) Glide and skip vehicles for space-ferry missions (Fig. 2), do notneed aerodynamic lift over parts of the trajectory—for instance, when the glide vehicle is spiralling in, and when the skip vehicleis moving along a ballistic trajectory. The glide vehicle would pre- sumably be so designed that the equilibrium temperature wouldbe marginally inside the limits shown for reference; the skip vehicle is a more severe case, but the high-temperature conditionis transient. In Fig. 3 is shown the standard flight envelope for sustainedflight with air-breathing power units and, superimposed, a possible envelope for anti-missile missiles where insulation techniques forthe main structure are an economical proposition. Table I sum- marizes characteristics for eight types of vehicle. In hypersonic flight, a good initial lifting capability is achievedwith a thick wedge-type wing, and high aspect ratio is not import- ant. Hypersonic vehicles can thus best be formed out of simple shapes such as cones andwedges, the whole volume being used for payload. Awhole family can be con- structed from simple trans-formations of the basic forms of sphere, cylinder, or cone(Figs. 4 and 5). Certain characteristics depend on crosssection as well as planform; in particular, stability require-ments may well lead to a dis- tribution of the total volumeso that a quasi-body appears as part of one surface of awing. Lifting capability for agiven body volume (and hence roughly for a givenweight) for a family of simple shapes is shown in Fig. 6.The effects of section stand out compared with those ofplanform. The results shown VELOCITY (u/sec x 1.000) are for a nominal 30 deg TABLE 1: CHARACTERISTICS FOR SIX TYPES OF VEHICLE Ballistic re-entry: Low drag High drag Skip vehicles: Long range Orbital re-entry Glide vehicles: Long range Orbital re-entry Sustained flight Anti-aircraft and anti-missile missiles Heating Very severe Severe Intermittently severe Intermittently severe Moderate Moderate Moderate Possibly severe for short time Order of weight (Ib) 103-101 103-10" 10-10s 10M0S 10M05 104-10? 10M0<> 10-'-10" Designaltitude (ftx1.000) 40-100 70-150 100-250 150-300 180-240 200-300 80-150 40-100 Max. CN Z Z VL VL L VL M L CDo S L M M M M S S Max. CDi zz L VL M VL M M L/D Z Z L S L S L M Manned No No No Yes No Yes Yes No Normal (lift.) 'g' zz L L S s s VL Longitudinal (decel.) V VL VL M M S M VS L Abbreviations: Z, lero; S, small; M, moderate; L, large; VL.'very large.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
