Commercializing the transfer orbit stage

Key milestones necessary to establish the transfer orbit stage are examined. The selection of the project concept and synthesis of the company are described followed by an analysis venture capability support and the selection of a major aerospace company as prime contractor. A landmark agreement with NASA sanctioned the commercial TOS concept and provided the critical support necessary to raise the next round of venture capital. Project management and customer commitments are also discussed

The Dynairship

A feasibility analysis for the construction and use of a combination airplane-airship named 'Dynairship' is undertaken. Payload capacities, fuel consumption, and the structural design of the craft are discussed and compared to a conventional commercial aircraft (a Boeing 747). Cost estimates of construction and operation of the craft are also discussed. The various uses of the craft are examined (i.e, in police work, materials handling, and ocean surveillance), and aerodynamic configurations and photographs are shown

The Hilbert Action in Regge Calculus

The Hilbert action is derived for a simplicial geometry. I recover the usual Regge calculus action by way of a decomposition of the simplicial geometry into 4-dimensional cells defined by the simplicial (Delaunay) lattice as well as its dual (Voronoi) lattice. Within the simplicial geometry, the Riemann scalar curvature, the proper 4-volume, and hence, the Regge action is shown to be exact, in the sense that the definition of the action does not require one to introduce an averaging procedure, or a sequence of continuum metrics which were common in all previous derivations. It appears that the unity of these two dual lattice geometries is a salient feature of Regge calculus.Comment: 6 pages, Plain TeX, no figure

Geometry and General Relativity in the Groupoid Model with a Finite Structure Group

In a series of papers we proposed a model unifying general relativity and quantum mechanics. The idea was to deduce both general relativity and quantum mechanics from a noncommutative algebra ${\cal A}_{\Gamma}$ defined on a transformation groupoid $\Gamma$ determined by the action of the Lorentz group on the frame bundle $(E, \pi_M, M)$ over space-time $M$. In the present work, we construct a simplified version of the gravitational sector of this model in which the Lorentz group is replaced by a finite group $G$ and the frame bundle is trivial $E=M\times G$. The model is fully computable. We define the Einstein-Hilbert action, with the help of which we derive the generalized vacuum Einstein equations. When the equations are projected to space-time (giving the "general relativistic limit"), the extra terms that appear due to our generalization can be interpreted as "matter terms", as in Kaluza-Klein-type models. To illustrate this effect we further simplify the metric matrix to a block diagonal form, compute for it the generalized Einstein equations and find two of their "Friedmann-like" solutions for the special case when $G =\mathbb{Z}_2$. One of them gives the flat Minkowski space-time (which, however, is not static), another, a hyperbolic, linearly expanding universe.Comment: 32 page

Interaction between superconductor and ferromagnetic domains in iron sheath: peak effect in MgB2/Fe wires

Interaction between the superconductor and ferromagnet in MgB2/Fe wires results in either a plateau or a peak effect in the field dependence of transport critical current, Ic(H). This is in addition to magnetic shielding of external field. Current theoretical models cannot account for the observed peak effect in Ic(H). This paper shows that the theoretical explanation of the peak effect should be sought in terms of interaction between superconductor and magnetic domain structure, obtained after re-magnetization of the iron sheath by the self-field of the current. There is a minimum value of critical current, below which the re-magnetization of the iron sheath and peak effect in Ic(H) are not observed

Observations on pulsating auroras

Photometric observations of pulsating aurora

Flutter Investigation of 60 Degree to 80 Degree Delta-Planform Surfaces at a Mach Number of 7.0

The flutter characteristics of a series of half-span delta surfaces which had leading-edge sweep angles ranging from 60 degrees to 80 degrees were investigated in helium flaw at a Mach number of 7.0 in the Langley hypersonic aeroelasticity tunnel. For each value of sweep angle both wedge and double-wedge airfoil sections were tested at two pitch-axis positions, The models were mounted so that a rigid-body flapping-pitching type of flutter was encountered. Analysis of the results and comparison with theory show that the wedge models are more stable than the corresponding double-wedge models; the pitch-axis location at or near the center of gravity is more stable than the more forward location; the effects of leading-edge sweep angle on the flutter characteristics appear to be small; and an uncoupled-mode piston-theory analysis gave the best agreement with the experimental results