Static tests of 4-inch outside-diameter frangible tube energy absorbers for nuclear aircraft
Static tests of aluminum and steel frangible tube energy absorbers for nuclear aircraft reactors
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Static tests of aluminum and steel frangible tube energy absorbers for nuclear aircraft reactors
Results of the static testing (zero forward speed) of the J97-powered, external augmentor, large scale, V/STOL model are discussed. With a ground clearance of 7.5 feet, believed to have put the model essentially out of ground effect, a gross thrust augmentation ratio of 1.60 at nozzle pressure ratio (NPR) = 3.0 was measured for the fuselage augmentor. A similar figure was apparent for the wing augmentor. An overall ratio of model thrust to bare engine thrust of 1.52 was determined at NPR = 3.0. The structural integrity of the model was well demonstrated and duct pressure losses were small.
This paper describes all of the work necessary to perform the static test of an ultralight airplane. A steel reaction gantry was designed first, then all of the loading whiffletrees, the hydraulic actuation system, and instrumentation systems were designed. Loads and stress analyses were performed on the airplane and the gantry and whiffletrees. Components tested to date are: tubing samples, cables, and two-by-four whiffletrees. A hydraulic system consisting of a 3000-psi hand pump, 10,000-pound actuator, pressure gage and lines, and a Barksdale valve are described. Load cell calibration and pressure indicator calibration procedures are also described. A description of the strain and deflection measurement system is included. Preliminary data obtained to date are compared to the analytical predictions.
A jet diffuser for simulating flight or ram conditions on a turbojet-engine static test stand was designed and investigated. The diffuser utilizes the kinetic energy of the jet from a turbojet engine to reduce the discharge pressure at the exhaust nozzle and thereby provides simulated ram-pressure ratios across the engine. The engine exhaust nozzle discharges into an exhaust chamber (flexibly sealed to the tail pipe), which is connected to a diffuser by a bell-shaped nozzle. The pressure in the exhaust chamber is controlled independently of engine speed by a variable-area shutter at the diffuser discharge. The jet diffuser simulated ram-pressure ratios from 0.95 to 2.2 at various simulated pressure altitudes for a range of engine speeds from 85 to 100 percent of maximum rpm. Agreement of data obtained with and without the jet diffuser for a ram-pressure ratio of 1.0 indicated that the presence of the diffuser did not interfere with the flow through the engine exhaust-nozzle outlet.
Attention is given to the application of the adjoint variable method under the special combination of displacement and stress boundary conditions which occur when static test conditions are simulated. In the two-step problem-solving method employed, calculation of internal stresses, displacements and total reaction force at the boundary is followed by the calculation of the applied load and the total reaction force due to unit displacements.
Static performance and acoustic tests were conducted on a two-dimensional one-third-scale augmentor flap model that simulated a cruise blowing augmentor system designed for a scale augmentor flap model that simulated a cruise blowing augmentor, which offers a degree of 150-passenger STOL airplane. The cruise blowing augmentor, which offers a degree of simplicity by requiring no fan air diverter valves, was simulated by fitting existing lobe suppressor nozzles with new nozzle fairings. Flow turning performance of the cruise blowing augmentor was measured through a large range of flap deflection angles. The noise suppression characteristics of a multilayer acoustic lining installed in the augmentor were also measured.
The effect of external air flowing across exhaust nozzles on the jet noise characteristics of supersonic transport aircraft at high takeoff speeds was investigated. A series of flyover and static tests were conducted using an F-106B aircraft modified with two underwing nacelles each containing a calibrated J85-GE-13 turbojet engine. Comparison of flyover and static data indicated that external flow reduces the noise of an auxiliary inlet ejector nozzle. An unsuppressed plug nozzle was not affected while the plug suppressor configurations were not as effective in flight.
The ability to withstand extreme environmental conditions, such as the high flow velocities and extreme temperatures associated with the launch of aerospace vehicles, was considered in the developement of two maxometer models which are capable of measuring extremely high wind speeds (130 m/sec) and retaining a record of the peak speed over any given time period. The dynamic and static tests of these models are reported, along with pertinent results.
The far-field acoustic data for eight full-scale fans tested at a NASA-Lewis outdoor facility were analyzed for the effect of a cut-off design feature where the number of rotor and stator blades are proportioned so that the blade-passage tone will not propagate. Inlet flow distortions, prevalent during static testing, interact with the rotor to generate tones that generally mask this cut-off phenomenon. Distortion tone properties previously evaluated are used to analyze the tones propagating from the aft fan duct. The analyzed data clearly differentiated the fans that are and are not cut-off.
Level flight airframe vibration at main rotor excitation frequencies was calculated. A NASTRAN tailboom analysis was compared with test data for evaluation of methods used to determine effective skin in a semimonocoque sheet-stringer structure. The flight vibration correlation involved comparison of level flight vibration for two helicopter configurations: clean wing, at light gross weight and wing stores at heavy gross weight. In the tailboom correlation, deflections and internal loads were compared using static test data and a NASTRAN analysis. An iterative procedure was used to determine the amount of effective skin of buckled panels under compression load.
One quarter scale static ground tests of the Boeing YC-14 powered lift system were conducted for correlation with full scale test results. The 1/4 scale model utilized a JT-15D turbofan engine to represent the CF6-50D engine employed on the YC-14 advanced medium STOL transport prototype aircraft. The tests included evaluation of static turning performance, static surface pressure and temperature distributions, fluctuating loads, and accelerations of portions of the wing, flaps, and fuselage. Results are presented for the landing flap configuration over an appropriate range of fan pressure ratio as affected by several variables including ground height and vortex generator modifications. Static turning angles of the order of 60 deg were obtained. The highest surface pressures and temperatures were concentrated over the upper surface of the flaps in the region immediately aft of the upper surface blown nozzle.
NASA’s high efficiency megawatt motor (HEMM) is a partially superconducting, 1.4 MW electric machine designed for electrified aircraft propulsion. HEMM’s high performance is enabled by a field winding composed of 2nd generation high temperature superconducting (HTS) coils that are designed to operate at temperatures below 62 K. The superconducting rotor is conductively cooled to cryogenic temperatures using a rotating cryocooler embedded inside the machine’s shaft. This paper presents a static test of the full-scale superconducting rotor in a thermal vacuum chamber. The experimental setup is described in detail. Thermal and electromagnetic 3D finite element analyses of the experimental setup are shown along with a comparison of the model results to model results for HEMM. The thermal response during cool down from room temperature is discussed. Electrical measurements are presented for operation at different dc current excitations up to the rated current of the rotor (57.2 A) and temperature limit of the HEMM design (62 K). The results suggest that minor damage to one superconducting coil occurred at 50 A and 61.2 K, causing increased resistance in the system, but that the system could still be stably operated at 57.2 A and 62 K when conductively cooled by a cryocooler.
Probabilistic engineering design enhances safety and reduces costs by incorporating risk assessment directly into the design process. In this paper, we assess the format of the quantitative metrics for the vehicle which will replace the Space Shuttle, the Ares I rocket. Specifically, we address the metrics for in-flight measurement error in the vector position of the motor nozzle, dictated by limits on guidance, navigation, and control systems. Analyses include the propagation of error from measured to derived parameters, the time-series of dwell points for the duty cycle during static tests, and commanded versus achieved yaw angle during tests. Based on these analyses, we recommend a probabilistic template for specifying the maximum error in angular displacement and radial offset for the nozzle-position vector. Criteria for evaluating individual tests and risky decisions also are developed.
Ground static and wind tunnel test of a scale model modified T-39 airplane are reported. The configuration in the nose and replacement of the existing nacelles with tilting lift/cruise fans. The model was powered with three 14 cm diameter tip driven turbopowered simulators. Forces and moments were measured by an internal strain guage balance. Engine simulator thrust and mass flow were measured by calibrated pressure and temperature instrumentation mounted downstream of the fans. The low speed handling qualities and general aerodynamic characteristics of the modified T-39 were defined. Test variables include thrust level and thrust balance, forward speed, model pitch and sideslip angle at forward speeds, model pitch, roll, and ground height during static tests, lift/cruise fan tilt angle, flap and aileron deflection angle, and horizonal stabilizer angle. The effects of removing the landing gear, the lift/cruise fans, and the tail surfaces were also investigated.
Two spoke-type suppressor plug nozzles and a basic plug nozzle were tested for noise and thrust performance. The nozzles were mounted on an underwing nacelle on an F-106B aircraft, and tests were made both statically and in flyovers at Mach 0.4 at an altitude of 91 meters (300 ft). The flight and static data were adjusted to common reference conditions so that direct comparisons could be made. The noise characteristics that these nozzles would have on a large multiengine aircraft at a 640-meter (2100-ft) sideline distance are also presented. Flight noise levels for all three nozzles were higher than static at comparable conditions; and a shift in the frequency spectra was seen from static to flight, indicating the presence of a forward velocity effect on the noise characteristics.
NASTRAN program differential stiffness method applied to structural analysis of Apollo Telescope Mount solar array wing and results compared with static load tests
Twin thruster tests have been conducted with the Penn State RBCC test article operating at sea- level static conditions. Significant differences were observed in the performance characteristics for two different thruster centerline spacings. Changing the thruster spacing from 2.50 to 1.75 in. reduced the entrained air velocity (-17%) and the thrust (-7%) for tests at a thruster chamber pressure of 200 psia and MR = 8. In addition, significant differences were seen in the static pressure profiles, the Raman spectroscopy profiles, and the acoustic power spectrum for these two configurations.
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