Self inductance of a wire loop as a curve integral

It is shown that the self inductance of a wire loop may be written as a curve integral akin to the Neumann formula for the mutual inductance of two wire loops. The only difference is that contributions where the two integration variables get too close to each other must be excluded from the curve integral and evaluated in detail. The contributions of these excluded segments depend on the distribution of the current in the cross section of the wire. They add to a simple constant proportional to the wire length. The error of the new expression is of first order in the wire radius if there are sharp corners and of second order in the wire radius for smooth wire loops.Comment: 3 figure

Experience with integrally-cast compressor and turbine components for a small, low-cost, expendable-type turbojet engine

Experiences with integrally-cast compressor and turbine components during fabrication and testing of four engine assemblies of a small (29 cm (11 1/2 in.) maximum diameter) experimental turbojet engine design for an expendable application are discussed. Various operations such as metal removal, welding, and re-shaping of these components were performed in preparation of full-scale engine tests. Engines with these components were operated for a total of 157 hours at engine speeds as high as 38,000 rpm and at turbine inlet temperatures as high as 1256 K (1800 F)

Critical phenomena of RNA-like polymers -- a synopsis

This work examines field theories for RNA-like polymers with single strand and double strand polymers and a periodic base sequence. These field theories originate from lattice models, describe polymers in a good solvent, and in principle exactly describe the critical behavior. A central role is played by the conventional one-component branched polymer and the mapping of the corresponding field theory to the Lee-Yang field theory in two less dimensions. Critical phenomena in the context of polymers as well as the Lee-Yang model entail pecularities, which we derive in detail. A new result is that the critical point of RNA-like branched polymers (with periodic base sequence) looks like the critical point of the classical one-component branched polymer, but with one more critical exponent for the single strand polymer. A random base sequence generates additional relevant interactions, and invalidates the simple picture

Small, low cost, expendable turbojet engine. 2: Performance characteristics

A small experimental axial-flow turbojet engine was tested at sea level static conditions and over a range of simulated flight conditions to evaluate its performance as well as to demonstrate the feasibility of low-cost concepts utilized in its design. Testing was conducted at engine speeds as high as 37,000 rpm and at turbine inlet temperatures as high as 1,272 K. For maximum speed the engine produced a net thrust of 3,118 newtons at sea level static operation and 2,318 newtons at its cruise condition of M0 = 0.8 and 6,096 meters. Data obtained over a range of inlet Reynolds number indexes for nominal M0 of 0.38 revealed similar effects or trends on compressor characteristics of those previously established for much larger engines

Lightweight, self-evacuated insulation panels

Multilayer insulation of prefabricated panels is developed for cryogenic storage tanks. System utilizes panels of aluminized Mylar separated by sheets of low conductivity polyurethane foam. Panels are self-evacuated by cryopumping of gaseous carbon dioxide at time of use

Advanced secondary power system for transport aircraft

A concept for an advanced aircraft power system was identified that uses 20-kHz, 440-V, sin-wave power distribution. This system was integrated with an electrically powered flight control system and with other aircraft systems requiring secondary power. The resulting all-electric secondary power configuration reduced the empty weight of a modern 200-passenger, twin-engine transport by 10 percent and the mission fuel by 9 percent

Self inductance of a wire loop as a curve integral

It is shown that the self inductance of a wire loop can be written as a curve integral akin to the Neumann formula for the mutual inductance of two wire loops. The only difference is that contributions where the two integration variables get too close to each other must be excluded from the curve integral and evaluated in detail. The contributions of these excluded segments depend on the distribution of the current in the cross section of the wire. They add to a simple constant proportional to the wire length. The error of the new expression is of first order in the wire radius if there are sharp corners and of second order in the wire radius for smooth wire loops