Engineering topics

Mcconnell, J. G.

Publications and source records attributed to Mcconnell, J. G..

11 records

NASA NTRS1985

Post-flight BET products for the 2nd discovery entry, STS-19 (51-A)

The post-flight products for the second Discovery flight, STS-19 (51-A), are summarized. The inertial best estimate trajectory (BET), BT19D19/UN=169750N, was developed using spacecraft dynamic measurements from Inertial Measurement Unit 2 (IMU2) in conjunction with the best tracking coverage available for any of the earlier Shuttle entries. As a consequence of the latter, an anchor epoch was selected which conforms to an initial altitude of greater than a million feet. The Extended BET, ST19BET/UN=274885C, incorporated the previously mentioned inertial reconstructed state information and the Langley Atmospheric Information Retrieval System (LAIRS) atmosphere, ST19MET/UN=712662N, with some minor exceptions. Primary and back-up AEROBET reels are NK0165 and NK0201, respectively. This product was only developed over the lowermost 360 kft altitude range due to atmosphere problems but this relates to altitudes well above meaningful signal in the IMUs. Summary results generated from the AEROBET for this flight are presented with meaningful configuration and statistical comparisons from the previous thirteen flights. Modified maximum likelihood estimation (MMLE) files were generated based on IMU2 and the Rate Gyro Assembly/Accelerometer Assembly (RGA/AA), respectively. Appendices attached define spacecraft and physical constants utilized, show plots of the final tracking data residuals from the post-flight fit, list relevant parameters from the BET at a two second spacing, and retain for archival purpose all relevant input and output tapes and files generated.

Kelly, G. M.↗

NASA NTRS1985

Challenger STS-17 (41-G) post-flight best estimate trajectory products: Development and summary results

Results from the STS-17 (41-G) post-flight products are presented. Operational Instrumentation recorder gaps, coupled with the limited tracking coverage available for this high inclination entry profile, necessitated selection of an anchor epoch for reconstruction corresponding to an unusually low altitude of h approx. 297 kft. The final inertial trajectory obtained, BT17N26/UN=169750N, is discussed in Section I, i.e., relative to the problems encountered with the OI and ACIP recorded data on this Challenger flight. Atmospheric selection, again in view of the ground track displacement from the remote meteorological sites, constituted a major problem area as discussed in Section II. The LAIRS file provided by Langley was adopted, with NOAA data utilized over the lowermost approx. 7 kft. As discussed in Section II, the Extended BET, ST17BET/UN=274885C, suggests a limited upper altitude (H approx. 230 kft) for which meaningful flight extraction can be expected. This is further demonstrated, though not considered a limitation, in Section III wherein summary results from the AEROBET (NJ0333 with NJ0346 as duplicate) are presented. GTFILEs were generated only for the selected IMU (IMU2) and the Rate Gyro Assembly/Accelerometer Assembly data due to the loss of ACIP data. Appendices attached present inputs for the generation of the post-flight products (Appendix A), final residual plots (Appendix B), a two second spaced listing of the relevant parameters from the Extended BET (Appendix C), and an archival section (Appendix D) devoting input (source) and output files and/or physical reels.

Kelly, G. M.↗

NASA NTRS1985

Trajectory reconstruction and aerodynamic results from the first Discovery flight, STS-14(41-D)

Trajectory reconstruction results for the first Discovery flight are presented. Spacecraft dynamic measurements from IMU2 were utilized in conjunction with the ground based tracking data from two S-band stations, eight C-band, and five cameras at Edwards Air Force Base to determine the spacecraft trajectory from epoch through roll-out on Runway 17. Specifics as to the trajectory reconstruction are discussed in Section 1. The final inertial profile is BT14NO2/UN=169750N. Merging of this file with the final LAIRS atmosphere is discussed in Section 2. The final Extended BET is ST14BET/UN=274885C. Section 3 presents plots of relevant parameters from the AEROBET as well as aerodynamic performance comparison results. High frequency files for maneuver extraction were also generated as discussed in Section 4. Appendices are attached which contain: (1) spacecraft and physical parameters utilized, (2) final residuals obtained from the data fitting process, (3) listing of trajectory parameters, and (4) archival information.

Kelly, G. M.↗

NASA NTRS1984

Summary of shuttle data processing and aerodynamic performance comparisons for the first 11 flights

NASA Space Shuttle aerodynamic and aerothermodynamic research is but one part of the most comprehensive end-to-end flight test program ever undertaken considering: the extensive pre-flight experimental data base development; the multitude of spacecraft and remote measurements taken during entry flight; the complexity of the Orbiter aerodynamic configuration; the variety of flight conditions available across the entire speed regime; and the efforts devoted to flight data reduction throughout the aerospace community. Shuttle entry flights provide a wealth of research quality data, in essence a veritable flying wind tunnel, for use by researchers to verify and improve the operational capability of the Orbiter and provide data for evaluations of experimental facilities as well as computational methods. This final report merely summarizes the major activities conducted by the AMA, Inc. under NASA Contract NAS1-16087 as part of that interesting research. Investigators desiring more detailed information can refer to the glossary of AMA publications attached herein as Appendix A. Section I provides background discussion of software and methodology development to enable Best Estimate Trajectory (BET) generation. Actual products generated are summarized in Section II as tables which completely describe the post-flight products available from the first three-year Shuttle flight history. Summary results are presented in Section III, with longitudinal performance comparisons included as Appendices for each of the flights.

Findlay, J. T.↗

NASA NTRS1984

STS-13 (41-C) BET products

Results from the STS-13 (41-C) Shuttle entry flight are presented. The entry trajectory was reconstructed from an altitude of 700 kft through rollout on Runway 17 at EAFB. The anchor epoch utilized was April 13, 1984 13(h)1(m)30.(s)0 (46890(s).0) GMT. The final reconstructed inertial trajectory for this flight is BT13M23 under user catalog 169750N. Trajectory reconstruction and Extended BET development are discussed in Section 1 and 2, respectively. The NOAA totem-pole atmosphere extracted from the JSC/TRW BET was adopted in the development of the LaRC Extended BET, namely ST13BET/UN=274885C. The Aerodynamic BET was generated on physical nine track reel NC0728 with a duplicate copy on NC0740 for back-up. Plots of the more relevant parameters from the AEROBET are presented in Section 3. Section 4 discusses the MMLE input files created for STS-13. Appendices are attached which present spacecraft and physical constants utilized (Appendix A), residuals by station and data type (Appendix B), a two second spaced listing of trajectory and air data parameters (Appendix C), and input and output source products for archival (Appendix D).

Findlay, J. T.↗

NASA NTRS1984

Final STS-11 (41-B) best estimate trajectory products: Development and results from the first Cape landing

The STS-11 (41-B) postflight data processing is completed and the results published. The final reconstructed entry trajectory is presented. The various atmospheric sources available for this flight are discussed. Aerodynamic Best Estimate of Trajectory BET generation and plots from this file are presented. A definition of the major maneuvers effected is given. Physical constants, including spacecraft mass properties; final residuals from the reconstruction process; trajectory parameter listings; and an archival section are included.

Kelly, G. M.↗

NASA NTRS1984

STS-9 BET products

The final products generated for the STS-9, which landed on December 8, 1983 are reported. The trajectory reconstruction utilized an anchor epoch of GMT corresponding to an initial altitude of h 356 kft, selected in view of the limited tracking coverage available. The final state utilized IMU2 measurements and was based on processing radar tracking from six C-bands and a single S-band station, plus six photo-theodolite cameras in the vicinity of Runway 17 at Edwards Air Force Base. The final atmosphere (FLAIR9/UN=581199C) was based on a composite of the remote measured data and the 1978 Air Force Reference Atmosphere model. The Extended BET is available as STS9BET/UN=274885C. The AEROBET and MMLE input files created are discussed. Plots of the more relevant parameters from the AEROBET (reel number NL0624) are included. Input parameters, final residual plots, a trajectory listing, and data archival information are defined.

Findlay, J. T.↗

NASA NTRS1984

Shuttle 'Challenger' aerodynamic performance from flight data - Comparisons with predicted values and 'Columbia' experience

Longitudinal aerodynamic performance comparisons between flight extracted and predicted values are presented for the first eight NASA Space Shuttle entry missions. Challenger results are correlated with the ensemble five flight Columbia experience and indicate effects due to differing angle-of-attack and body flap deflection profiles. An Appendix is attached showing the results of each flight using both the LaRC LAIRS and NOAA atmospheres. Discussions are presented which review apparent density anomalies observed in the flight data, with particular emphasis on the suggested shears and turbulence encountered during STS-2 and STS-4. Atmospheres derived from Shuttle data are presented which show structure different than that remotely sensed and imply regions of unstable air masses as a plausible explanation. Though additional aerodynamic investigations are warranted, an added benefit of Shuttle flight data for atmospheric research is discussed, in particular, as applicable to future NASA space vehicles such as AOTVs and tethered satellites.

Findlay, J. T.↗

NASA NTRS1983

STS-8 bet results

The final Best Estimate Trajectory (BET) products, i.e., the reconstructed trajectory, the Extended BET, AEROBET and MMLE input files, generated for the eighth NASA Space Shuttle flight are documented. The reconstructed trajectory (inertial BET) for this Challenger flight, the first night landing is discussed. State (position, velocity, and attitude) plus three accelerometer scale factors were determined from fitting the Guam S-band data, seven C-band passes, and pseudo Doppler and altimeter during rollout on Runway 22. The anchor epoch utilized for the batch weighted-least-squares determination was Sept. 5, 1983 7h1m50s.0 (25310 GMT seconds). The spacecraft altitude at epoch is approx. 617 kft. IMU2 data were selected for the reconstruction.

Findlay, J. T.↗

NASA NTRS1983

Subsonic Longitudinal Performance Coefficient Extraction from Shuttle Flight Data: an Accuracy Assessment for Determination of Data Base Updates

Longitudinal performance comparisons between flight derived and predicted values are presented for the first five NASA Space Shuttle Columbia flights. Though subsonic comparisons are emphasized, comparisons during the transonic and low supersonic regions of flight are included. Computed air data information based on the remotely sensed atmospheric measurements as well as in situ Orbiter Air Data System (ADS) measurements were incorporated. Each air data source provides for comparisons versus the predicted values from the LaRC data base. Principally, L/D, C sub L, and C sub D, comparisons are presented, though some pitching moment results are included. Similarities in flight conditions and spacecraft configuration during the first five flights are discussed. Contributions from the various elements of the data base are presented and the overall differences observed between the flight and predicted values are discussed in terms of expected variations. A discussion on potential data base updates is presented based on the results from the five flights to date.

Findlay, J. T.↗

NASA NTRS1981

Inertial measurement unit pre-processors and post-flight STS-1 comparisons

The flight results show that the relative tri-redundant Inertial Measurement Unit IMU performance throughout the entire entry flight was within the expected accuracy. Comparisons are presented which show differences in the accumulated sensed velocity changes as measured by the tri-redundant IMUs (in Mean Equator and Equinox of 1950.0), differences in the equivalent inertial Euler angles as measured with respect to the M50 system, and finally, preliminary instrument calibrations determined relative to the ensemble average measurement set. Also, differences in the derived body axes rates and accelerations are presented. Because of the excellent performance of the IMUs during the STS-1 entry, the selection as to which particular IMU would best serve as the dynamic data source for entry reconstruction is arbitrary.

Findlay, J. T.↗