Flight characteristics of a manned, low-speed, controlled deep stall vehicle

A successful manned, low speed, controlled deep stall flight research program was conducted at NASA Ames Research Center's Dryden Flight Research Facility. Piloting techniques were established that enabled the pilot to attain and stabilize on an angle of attack in the 30 deg to 72 deg range. A flight determined aerodynamic data base was established for angles of attack as high as 72 deg. Poor lateral directional flying qualities were encountered at angles of attack above 60 deg. Insight into the high angle of attack lateral directional dynamics was gained through a basic root locus analysis

A comparison of Wortmann airfoil computer-generated lift and drag polars with flight and wind tunnel results

Computations of drag polars for a low-speed Wortmann sailplane airfoil are compared with both wind tunnel and flight test results. Excellent correlation was shown to exist between computations and flight results except when separated flow regimes were encountered. Smoothness of the input coordinates to the PROFILE computer program was found to be essential to obtain accurate comparisons of drag polars or transition location to either the flight or wind tunnel flight results

In-flight total forces, moments and static aeroelastic characteristics of an oblique-wing research airplane

A low-speed flight investigation has provided total force and moment coefficients and aeroelastic effects for the AD-1 oblique-wing research airplane. The results were interpreted and compared with predictions that were based on wind tunnel data. An assessment has been made of the aeroelastic wing bending design criteria. Lateral-directional trim requirements caused by asymmetry were determined. At angles of attack near stall, flow visualization indicated viscous flow separation and spanwise vortex flow. These effects were also apparent in the force and moment data

Flight-determined aerodynamic derivatives of the AD-1 oblique-wing research airplane

The AD-1 is a variable-sweep oblique-wing research airplane that exhibits unconventional stability and control characteristics. In this report, flight-determined and predicted stability and control derivatives for the AD-1 airplane are compared. The predictions are based on both wind tunnel and computational results. A final best estimate of derivatives is presented

Flight evaluation of the M2-F3 lifting body handling qualities at Mach numbers from 0.30 to 1.61

Percentage distributions of 423 pilot ratings obtained from 27 flights are used to indicate the general level of handling qualities of the M2-F3 lifting body. Percentage distributions are compared on the basis of longitudinal and lateral-directional handling qualities, control system, control system status, and piloting task. Ratings of longitudinal handling qualities at low speed were slightly better than those for transonic and supersonic speed. The ratings of lateral-directional handling qualities were unaffected by speed and configuration. Specific handling qualities problems are discussed in detail, and comparisons are made with pertinent handling qualities criteria

Results of a feasibility study using the Newton-Raphson digital computer program to identify lifting body derivatives from flight data

A brief study was made to assess the applicability of the Newton-Raphson digital computer program as a routine technique for extracting aerodynamic derivatives from flight tests of lifting body types of vehicles. Lateral-direction flight data from flight tests of the HL-10 lifting body reserch vehicle were utilized. The results in general, show the computer program to be a reliable and expedient means for extracting derivatives for this class of vehicles as a standard procedure. This result was true even when stability augmentation was used. As a result of the study, a credible set of HL-10 lateral-directional derivatives was obtained from flight data. These derivatives are compared with results from wind-tunnel tests

Flight-determined stability and control characteristics of the M2-F3 lifting body vehicle

Flight data were obtained over a Mach number range from 0.4 to 1.55 and an angle-of-attack range from -2 deg to 16 deg. Lateral-directional and longitudinal derivatives, reaction control rocket effectiveness, and longitudinal trim information obtained from flight data and wind-tunnel predictions are compared. The effects of power, configuration change, and speed brake are discussed

Understanding the fidelity effect when evaluating games with children

There have been a number of studies that have compared evaluation results from prototypes of different fidelities but very few of these are with children. This paper reports a comparative study of three prototypes ranging from low fidelity to high fidelity within the context of mobile games, using a between subject design with 37 participants aged 7 to 9. The children played a matching game on either an iPad, a paper prototype using screen shots of the actual game or a sketched version. Observational data was captured to establish the usability problems, and two tools from the Fun Toolkit were used to measure user experience. The results showed that there was little difference for user experience between the three prototypes and very few usability problems were unique to a specific prototype. The contribution of this paper is that children using low-fidelity prototypes can effectively evaluate games of this genre and style

Flight-determined stability and control derivatives for the F-111 Tact research aircraft

A flight investigation was conducted to provide a stability and control derivative data base for the F-111 transonic aircraft technology research aircraft. Longitudinal and lateral-directional data were obtained as functions of Mach number, angle of attack, and wing sweep. For selected derivatives, the flight results were correlated with derivatives calculated based on vehicle geometry. The validity of the angle of attack measurement was independently verified at a Mach number of 0.70 for angles of attack between 3 and 10 degrees

Constraints on explosive silicon burning in core-collapse supernovae from measured Ni/Fe ratios

Measurements of explosive nucleosynthesis yields in core-collapse supernovae provide tests for explosion models. We investigate constraints on explosive conditions derivable from measured amounts of nickel and iron after radioactive decays using nucleosynthesis networks with parameterized thermodynamic trajectories. The Ni/Fe ratio is for most regimes dominated by the production ratio of 58Ni/(54Fe + 56Ni), which tends to grow with higher neutron excess and with higher entropy. For SN 2012ec, a supernova that produced a Ni/Fe ratio of $3.4\pm1.2$ times solar, we find that burning of a fuel with neutron excess $\eta \approx 6\times 10^{-3}$ is required. Unless the progenitor metallicity is over 5 times solar, the only layer in the progenitor with such a neutron excess is the silicon shell. Supernovae producing large amounts of stable nickel thus suggest that this deep-lying layer can be, at least partially, ejected in the explosion. We find that common spherically symmetric models of $M_{\rm ZAMS} \lesssim 13$ Msun stars exploding with a delay time of less than one second ($M_{\rm cut} < 1.5$ Msun) are able to achieve such silicon-shell ejection. Supernovae that produce solar or sub-solar Ni/Fe ratios, such as SN 1987A, must instead have burnt and ejected only oxygen-shell material, which allows a lower limit to the mass cut to be set. Finally, we find that the extreme Ni/Fe value of 60-75 times solar derived for the Crab cannot be reproduced by any realistic-entropy burning outside the iron core, and neutrino-neutronization obtained in electron-capture models remains the only viable explanation.Comment: 13 pages, 9 figures, accepted for publication in Ap