A Feasibility Study of the Flare-Cylinder Configuration as a Reentry Body Shape for an Intermediate Range Ballistic Missile

A study has been made of a flare-cylinder configuration to investigate its feasibility as a reentry body of an intermediate range ballistic missile. Factors considered were heating, weight, stability, and impact velocity. A series of trajectories covering the possible range of weight-drag ratios were computed for simple truncated nose shapes of varying pointedness, and hence varying weight-drag ratios. Four trajectories were chosen for detailed temperature computation from among those trajectories estimated to be possible. Temperature calculations were made for both "conventional" (for example, copper, Inconel, and stainless steel) and "unconventional" (for example, beryllium and graphite) materials. Results of the computations showed that an impact Mach number of 0.5 was readily obtainable for a body constructed from conventional materials. A substantial increase in subsonic impact velocity above a Mach number of 0.5 was possible without exceeding material temperature limits. A weight saving of up to 134 pounds out of 822 was possible with unconventional materials. This saving represents 78 percent of the structural weight. Supersonic impact would require construction of the body from unconventional materials but appeared to be well within the range of attainability

Phase 2 and 3 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Static and forward speed tests were made in a 40 multiplied by 80 foot wind tunnel of a large-scale, ejector-powered V/STOL aircraft model. Modifications were made to the model following earlier tests primarily to improve longitudinal acceleration capability during transition from hovering to wingborne flight. A rearward deflection of the fuselage augmentor thrust vector was shown to be beneficial in this regard. Other augmentor modifications were tested, notably the removal of both endplates, which improved acceleration performance at the higher transition speeds. The model tests again demonstrated minimal interference of the fuselage augmentor on aerodynamic lift. A flapped canard surface also showed negligible influence on the performance of the wing and of the fuselage augmentor

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic): Alewife/Blueback Herring

This profile covers life history and environmental requirements of both alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), since their distribution is overlapping and their morphology, ecological role, and environmental requirements are similar. The alewife is an anadromous species found in riverine, estuarine, and Atlantic coastal habitats, depending on life cycle stage, from Newfoundland (Winters et al. 1973) to Soutn Carolina (Berry 1964). Landlocked populations are i n the Great Lakes, Finger Lakes, and many other freshwater lakes (Bigelow and Sch roeder 1953; Scott and Crossman 1973). The blueback herring is an anadromous species found in riverine, estuarine, and Atlantic coastal habitats, depending on life stage cycle, from Nova Scotia to the St. Johns River, Florida (Hildebrand 1963

Monte Carlo methods for estimating, smoothing, and filtering one- and two-factor stochastic volatility models

One- and two-factor stochastic volatility models are assessed over three sets of stock returns data: S&P 500, DJIA, and Nasdaq. Estimation is done by simulated maximum likelihood using techniques that are computationally efficient, robust, straightforward to implement, and easy to adapt to different models. The models are evaluated using standard, easily interpretable time-series tools. The results are broadly similar across the three data sets. The tests provide no evidence that even the simple single-factor models are unable to capture the dynamics of volatility adequately; the problem is to get the shape of the conditional returns distribution right. None of the models come close to matching the tails of this distribution. Including a second factor provides only a relatively small improvement over the single-factor models. Fitting this aspect of the data is important for option pricing and risk management

SV mixture models with application to S&P 500 index returns

Understanding both the dynamics of volatility and the shape of the distribution of returns conditional on the volatility state is important for many financial applications. A simple single-factor stochastic volatility model appears to be sufficient to capture most of the dynamics. It is the shape of the conditional distribution that is the problem. This paper examines the idea of modeling this distribution as a discrete mixture of normals. The flexibility of this class of distributions provides a transparent look into the tails of the returns distribution. Model diagnostics suggest that the model, SV-mix, does a good job of capturing the salient features of the data. In a direct comparison against several affine-jump models, SV-mix is strongly preferred by Akaike and Schwarz information criteria

19-Archaeological Survey of the Environs of 20CX65, the Beaver lsland Sun Circle, Charlevoix County, Michigan

In October of 1988 I was contacted by Terri Bussey of the Grand Rapids Inter-Tribal Council concerning the putative Sun Circle at Beaver Island. She came to my office at the University a few days later, bringing maps and photographs, and we discussed the site at some length. This comprised my first direct information about the site, my prior knowledge being confined to remarks by students who had seen stories In the Detroit press, and some conversation with professional colleagues at the Midwest Archaeological Conference at Urbana-Champaign a week or two earlier. At Ms. Bussey\u27s. request I tentatively agreed to come to Beaver Island with a student field crew In early spring to carry out test excavation for the purpose of locating evidence of early historic or prehistoric activity In the vicinity of the Sun Circle. As a professional courtesy, I then wrote to Dr. Donald Heldman, Director of Archaeology, MISPC, whom I understood had carried out some limited excavation at the Sun Circle during the summer of 1988, in order to secure his agreement that I conduct more extensive testing. I also asked Dr. Heldman for information about any cultural materials he had found at or near the site. In a letter from Heldman to Garland, dated 6 December 1988, Dr. Heldman welcomed my plans to test excavate the presumed area of settlement near the Sun Circle (historically known as Peshawbestown), and provided information on his prior work, along with various interpretations of the Sun Circle. Heldman reported having excavated one 2 by 4 foot pit adjacent to and partially under the east side of the center stone In the Sun Circle. Using 1/4 inch mesh, he reported finding debitage In three strata: a black organically enriched layer Q at the top, a grey loam below this; and a brown loam below the grey stratum. He stated in this letter that he had been unable to find charcoal in the top layer. On January 24, 1989, I spoke by telephone with Dr. Earl Prahl who had twice visited the site during the previous summer. Accompanied by Terri Bussey, he had examined a number of surface features in and near the Sun Circle. Prahl stated that he excavated two 18 inch test squares, one 50 feet north and one 50 feet south of the center stone. He troweled out these tests and found nothing in either one. Prahl visited the site again shortly before Labor Day, 1988, accompanied by Dr. Charles Cleland. Cleland and Prahl mapped the Sun Circle at this time, and placed several small test excavations in other areas. They redug Heldman\u27s profile adjacent to the center stone, and concluded that the soil layers represented a podzol (Earl Prahl, personal communication). Prahl and Cleland recovered no debitage or other evidence of human activity in their limited testing. On February 1, 1989 I received from Earl Prahl the lithic materials found by Heldman in his pit excavation near the center stone. I examined this material the following day and concluded that it is of wholly natural origin, consisting of spalls from patinated glacial chert pebbles and miscellaneous blocky fragments of chert lacking platforms. Commentary to date concerning the Beaver Island Sun Circle, among archaeologists and in the press, has generated considerably more heat than light. As I informed Terri Bussey in October of 1988, my willingness to undertake test excavation would be narrowly focussed, with the following objectives: Expanded test excavation in the vicinity of the Sun Circle seemed to be a first priority; in particular it would be useful to determine if prehistoric settlement had existed in the vicinity of the historic Ottawa village Peshawbestown, located near the Sun Circle. The reported garden bed near the airport should be investigated. I would be unable to do follow up work (if indicated) myself, due to prior commitments, but another archaeologist would perhaps do so

Phase 1 wind tunnel tests of the J-97 powered, external augmentor V/STOL model

Test results are presented for a large scale, external augmentor V/STOL model in a 40 ft by 80 ft wind tunnel. The model was powered by a GE J97 engine and featured longitudinal ejectors alongside and external to the fuselage together with an augmentor flap on the low aspect ratio, double-delta wing. A static thrust augmentation ratio of 1.60 was measured for the fuselage augmentor at a nozzle pressure ratio of 3.0 and a nozzle exhaust gas temperature of 700 C. At forward speed the model showed a strong positive lift interference due to the augmentor flap, and a marked absence of negative lift interference due to the fuselage augmentor jet system. The nose-up moment of the fuselage augmentor inlet flow was approximately cancelled by a 60 deg deflection of the augmentor flap. An assessment of the thrust and drag components to allow the prediction of transition performance of aircraft designs based on the present conceptual model was made. Lateral tests showed strong but well ordered effects of power