Author: Drew Semiraro
The PEC Squat Cylinder In our previous article, we presented the PEC sphere as the first in a family of canonical targets whose scattering properties enhance practitioner understanding of scattering behavior, provide a mechanism to measure range health, and encourage the use of quality measurement tradecraft. This article is the second in a series of five where we describe the scattering properties and use of the PEC squat cylinder (PSC). Use of the PSC came to prominence in RCS measurements in the early 1990’s as the community sought to establish a uniform understanding of calibration errors.[1],[2],[3] The PSC has distinct…
The Sphere RCS measurement ranges typically come in two flavors: Research and Development (R&D) and Quality Control (QC). QC ranges are usually an extension of a production line, repeatedly measuring the backscatter (not necessarily far-field RCS) of similar targets, answering the question, “Does it pass?” Operators of QC ranges do not have to be skilled in the interpretation of scattering data but must know how to properly measure their specific target according to a well-defined test plan and know when deviations occur. QC ranges find their maximum usefulness in repeatability from one test to another and are often designed with…
The need to sample data While the world moves continuously around us, the RF measurement world, especially the antenna and RCS measurement communities, collect magnitude and phase data in discrete steps. These discrete steps may be incremental times, frequencies, positions, and angles. A police radar gun samples in discrete time intervals, RF network analyzers step in frequency, field probes increment distance, and rotators permit travel in angular increments. The length of each increment in seconds, Hertz, meters, or radians, is an important factor in the execution of RF measurements. The relationship between the length of a measurement interval and its…
What is a plane wave? Plane waves are an indispensable facet of RF measurements, theory, and analysis. A plane wave is an electromagnetic (EM) wave that travels with constant amplitude and phase in all directions perpendicular to the direction of propagation. Stated another way, it consists of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of propagation. In practical terms, EM waves begin as point sources that travel spherically outward with increasing diameter. Eventually, the wave travels far enough from its source (e.g. antenna) where a cross-section of the expanding sphere surface is…
The use of Fourier Transform in RF measurements There are few tools more helpful to RF engineers than the discrete Fourier Transform. Most students learn about the DFT based on sampled time and frequency examples apart from any physics associated with a particular application. However, when the sampled and transformed variables are linked together through physical realities such as bandwidth, time span, angular aperture, distance, and Doppler, the DFT becomes more than an isolated equation that undergraduates learn from a textbook. With a tailored expression of the DFT, and some relationships between the sample and transform variables, even a novice…
3-D innovation slashes production time boosts design options and provides owners greater participation in their aircraft build Surrounded by the stark white walls of an aircraft hangar, the Gulfstream G650, its exterior newly sanded and silky smooth, stands ready for its crowning touch: a painted exterior to distinguish the jet from all others. Two technicians perched atop a scissor lift carefully unroll masking tape along the aircraft. Every strip determines some aspect of the design, whether graceful curves over an engine cowling or razor-thin separations between stripes along the fuselage. Taping an exterior once took a crew of technicians anywhere…
December 8, 2020 – Westford, MA, USA – Delta Sigma Company and Zuken USA Inc. announced a partnership to bring enhanced manufacturing using augmented reality to the wire harness design and manufacturing process. Harness Builder for E³.series, part of Zuken’s popular electrical harness design suite of tools, now has the capability to drive Delta Sigma Company’s ProjectionWorks. This partnership falls under Zuken’s digital engineering initiative, providing a solution consistent with digital engineering practices by eliminating spreadsheets and manual processes. ProjectionWorks, an award-winning manufacturing automation solution, uses projection-based mixed reality technology to provide step by step visual instructions for harness assembly. By…
In this project, Delta Sigma produced two rollover systems – one mobile to take the F-22 center fuselage from the assembly building to the paint hanger about one-half mile away and the other a fixed clean-and-deFOD system in the assembly building. The Rollover Dolly was a Class 1 – Division 1 (explosion-proof) system that allowed the painter to raise, lower and roll the center fuselage to any desired height or angle. This provided very easy access to the many pockets in the aircraft and always allowed the painter to stand on the floor providing a safe and ergonomic work environment. …
Automating F-22 Aircraft Production The F-22 vertical stabilizer has a few thousand holes for fasteners that are drilled in a composite/composite stack or a composite/titanium stack. The hole diameters range from very small to quite large at the root. The absolute position of these holes requires a very high accuracy; however, the countersink depth is even more stringent. The countersink depth accuracy requirement is further complicated by the fact that the skin position tolerance is more than 10X greater than the countersink depth tolerance. Yet, the countersink depth is based on where the skin “is”, not where it “should have…
This project took a long difficult manual drilling process and fully automated it with a CNC system that was built for this purpose. The system design made it easy to load component parts and take out a completed assembly using the existing tooling. The Cargo Ramp Door for this aircraft was roughly 10 feet by 15 feet. The Auto-Drill system designed and built by Delta Sigma runs mostly autonomously to complete the entire process. The tool holder can hold enough tools for the full process. The Auto-Drill system is composed of a gantry on two long rails that are each…