Browse Topic: Displays
The biography of Henrich Focke is well known and documented. During a small period from October 1954 to February 1956 he held lectures at the Technical University of Stuttgart during the winter semester. In the summer period he returned to Brazil for continuation of his contract work on the "Convertiplane" (a quad-tiltrotor aircraft) and the "Bei-jaflor" (a small single rotor helicopter). The topic of Focke's lecture in the winter semester 1954-55 was "Design of Fixed-Wing Aircraft", but the lecture manuscript of it is unavailable. In the following period 1955-56 Focke lectured about "Helicopter Design" and the manuscript was recently found in the central archive of DLR. It covers 123 pages of text with sketches and graphs and provides deep insights into the helicopter design philosophy of Henrich Focke.
Piloted evaluations form a critical part of Handling Qualities (HQ) testing. Military rotorcraft standard ADS-33 outlines the widely accepted approach to perform HQ testing, including both methods to determine predicted and assigned HQs (Ref. 1). Recently, ADS-33 has been replaced with MIL-DTL-32742, which includes updates to previously defined criteria and tasks (Ref. 2). Assigned HQs are awarded using short-look tasks, so-called Mission Task Elements (MTEs), stylized to represent mission requirements. Test courses focus on external visual cues, used by the pilot to judge position. Setting up external courses is usually expensive and may not be feasibly possible. The MCRUER (Means of Compliance Requirements for UAM Evaluations and Ratings) system intends to support HQ evaluations, replacing physical test courses using virtual displays. Four MTEs were successfully demonstrated in flight by three pilots using a variable stability rotorcraft. HQ evaluations were performed both using physical courses (live) and the MCRUER virtual courses. Handling Qualities Ratings (HQRs) were found to be consistent across both live and virtual courses with identifiable trends. Differences observed between the two cueing environments are described. Overall, virtual displays were found to improve pilot adherence to task specifications, even exceeding live-courses for a specific tasks.
ABSTRACT
ABSTRACT Current and future military rotary-wing operations are anticipated to take place more frequently in urban environments. This will increase likelihood for the presence of obstacles along the flight path. In order to maintain safe and effective flights, cueing for obstacle detection and subsequent avoidance is needed. A study was completed to examine the utility of providing obstacle avoidance cues using multimodal cueing. Three different cueing configurations consisting of combinations of visual, auditory, and tactile cues that provided obstacle avoidance information were examined to evaluate their effect on pilots' situational awareness and workload. Pilots performed low-level flights in a dense urban area with obstacles present. Initial support for multimodal displays of obstacle information was found.
This paper reports on the integration, test and evaluation of a Degraded Visual Environment (DVE) system installed on an Airbus H145 (BK117 D-2) civil certified helicopter. The DVE system consists of a LiDAR sensor, an EVS camera and a head-tracked helmet mounted display system (HMD) integrated into the onboard HELIONIX® digital avionics suite. The DVE system combines sensor enhanced and synthetic elements of the external scene and provides an accurate representation of the real world for visual reference and safe manoeuvring in DVE. All systems were prototypically integrated into the H145 demonstrator in a serial-like manner, allowing for a potential serialization of the system. Extensive flight trials were conducted focusing on military as well as on civil HEMS missions and were used to verify the intended function and evaluate installed DVE system performance. The activities described herein are partially performed in the frame of a research project supported by the German Federal Office of Bundeswehr Equipment, Information Technology and In-Service Support (BAAINBw). Between November 2018 and March 2019 the system was successfully deployed in both ground and flight tests.
Helicopters are routinely used to transport crew to and from maritime wind farms. Inclement weather situations and demanding tasks put a high workload on pilots during these missions. This paper describes two test campaigns assessing the utility of a low cost Head-mounted display (HMD) to reduce workload for commercial maritime operations. This system was implemented within the Air Vehicle Simulator (AVES) at the German Aerospace Center (DLR). Three tasks were flown with experienced offshore pilots, performed in a realistic scenario. Independent subjective assessments of both workload and situational awareness were obtained. Results from the studies show that the overall workload for all missions decreased when using the HMD. Opinions regarding overall benefit and advantages of the system were found to vary between pilots and missions.
This paper presents preliminary results of a pilot-in-the-loop (PIL) study of different cueing designs to reduce pilot workload in rotorcraft shipboard landings. The participants were tasked with flying an approach to touchdown on the deck of an Arleigh Burke Flight IIA class Destroyer under both day visual flight rules (VFR) and night-unaided, zeroillumination conditions. For each condition, the participants were presented with three different cue types. For the day iterations these were a generic military standard heads up display (HUD), a ship fixed tunnel in the sky (tunnel), and a virtual flight lead cueing system (FLCS). The zero-illumination night condition was deemed impossible to land with only the HUD, so it was replaced with a combination of the tunnel and FLCS for the purpose of gaining initial feedback on combining elements of different systems. Terminal landing constraints (location, heading, and impact velocity) were used as measures of pilot performance, the NASA Task Load Index (TLX) survey was used to evaluate perceived pilot workload, and the System Usability Scale (SUS) was used to rate interface and cueing usability. Initial findings showed that pilots viewed the tunnel cueing as having the lowest perceived workload while the FLCS provided the best terminal performance. All types of 3D cueing improved performance when compared to the HUD baseline. The use of 3D cueing also expanded the operational envelope to include zero-illumination conditions. For completeness, the study requires additional subjects, specifically those that have prior shipboard landing experience, as COVID-19 safety precautions paused in-person simulator testing early in the testing period. This body of work represents the next iteration of FLCS research, initially published in Ref. 1.
Two sets of visual symbology in conjunction with two display types (helmet mounted and panel mounted) were examined for their usability in maintaining flight performance within a simulated degraded visual environment. Eight rated Army Aviators completed a series of flights using the two symbology sets with each display type. Flight performance data was collected and used to assess performance resulting from symbology and display used. Overall, the assessment found one symbology set to result in better performance across several phases of flight and no significant differences due to display type, although a few interactions between symbol set and display type are noted.
Rotor/wing interactions in tiltrotor aircraft are complex in nature. Using an XV-15 rotor on a full-span wing with a symmetric NACA 0023 airfoil section, the mechanisms of rotor/wing interactions are investigated for a tiltrotor aircraft cruising at 220 knots. Numerical computations are performed using HPCMP CREATE™-AV Helios code. Due to the rotor/wing interference, rotor and wing loadings display a 3-per-rev harmonic response. The mean rotor thrust and power are influenced by the interference. Due to the interference, the rotor thrust increases 12.7 percent and the rotor power increases 8.1 percent, most of which is due to wing thickness interference. The mean wing lift and drag are also influenced by the interference. Due to the interference, the wing lift increases 0.7 percent and the wing drag reduces 21.9 percent. These interference effects are confined to the high speed tiltrotor airplane mode.
Helicopter military missions such as combat search and rescue, medical evacuation and landing on unprepared sites can involve operating in hostile, low-altitude, and degraded visual environments (DVE). These conditions may significantly reduce the pilot's capability to use the natural out of the window (OTW) perceptual cues, increase workload and increase the risk of collision with terrain and natural or man-made obstacles. In modern helicopter cockpits, synthetic vision systems (SVSs) can employ conventional nonconformal two-dimensional (2D), egocentric three-dimensional (3D) conformal symbology (CS) and laser detection and ranging (LADAR)/ radio detection and ranging (RADAR)/ forward looking infrared (FLIR) imagery support guidance and control, especially during operations in DVE. Although 3D CS can decrease pilot workload, it can also produce attentional tunneling (cognitive capture) and may not provide maximally effective depiction of the environment around the helicopter. In this context, it is crucial to develop integrated multimodal interfaces that extend the current operational envelope while enhancing flight safety. Several flight simulator studies have investigated the use of spatial auditory displays (SADs) in combination with spatially and temporally congruent visual displays in tasks as diverse as collision avoidance, intruding aircraft detection, or system malfunction warning. In this paper we propose a novel approach to spatial sonification design based on the premises that perception-based synthetic cueing can increase situation awareness (SA), improve overall performance, and allow mental workload to be kept at operationally effective levels. This paper discusses the development, implementation, and evaluation of a sensor-based augmented-reality spatial auditory display (ARSAD) and its visual analog, an integrated collision avoidance display (ICAD) for all phases of flight. Five UH60M Army pilots participated in a low-level flight simulation evaluating the visual and the auditory displays, alone or in combination in low-visibility and zero visibility environments. The results are discussed in the context of pilot cueing synergies for DVE.
ABSTRACT Currently, manned vertical lift vehicles are flown in a manner such that the rotors operate over a narrow range of rotating speed regardless if the vehicle's flight condition is one of vertical takeoff and landing, hover, or forward cruise. The propulsion systems are optimized for operation at the same, corresponding narrow range of rotor speed. However, certain missions and markets benefit greatly if the rotor speed can be adjusted over a wide range of speed to match demands of different missions and flight regimes. A vehicle that can operate with a wide range of rotor speeds would address key barriers to enable new markets and missions for vertical lift vehicles. Key barriers addressed by the wide-range of rotor speed include noise reduced via lower rpm rotor, increase of maximum forward flight speed, increased payload and range, reduced fuel burn, and lower operating costs. A new paradigm for the propulsion system is needed to enable these key benefits. One viable approach is to make use of a two-speed ratio drive system such that the engine can continue to operate over a narrow speed range, whereby engine performance is optimal, while adjusting the rotor speed as needed using the two-speed drive system. Motivated by such needs and by results of several system studies, a NASA Revolutionary Vertical Lift Technology Challenge was established to develop and demonstrate required technologies and designs for achieving a 50 percent reduction in rotor rpm via a two-speed drive system that incurs less than 2 percent power loss and maintains current power-to-weight ratios. The technical challenge work was completed and the technical objectives were achieved. This report describes the motivations, the research approach and the significant outcomes.
ABSTRACT An experiment was conducted on a two-dimensional SC1094R8 airfoil model with the intention of investigating the cycle-to-cycle variations observed in dynamic stall. Unsteady surface pressure measurements were recorded at numerous points along the airfoil surface at specific pitching conditions that displayed more than one preferred reattachment process. Sets of individual cycles that represented the dominant reattachment processes were identified and compared to the phase-average, showing significant differences in pressure distributions and aerodynamic loads. Proper Orthogonal Decomposition was then employed to the unsteady pressure distributions with the intent of isolating the influence of specific modes on the cycle-to-cycle variations. The results indicate that the importance of the modes changes depending on the particular reattachment process observed. Approved for public release: distribution unlimited. Review completed by the AMRDEC Public Affairs Office (PR3 3750, 10 April 2018).
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