Flight Test Engineering Research Papers (original) (raw)

A crash that occurred in Boynton, FL was brought to the attention of j2 Aircraft Dynamics when a video had been produced that showed the events of the crash. j2 were asked whether they would be able to do the same, and what else they could do to add further information. J2 were not provided with any further details on the aircraft or incident that could not be sourced through freely available documentation. No contact was made with Cirrus for additional details/drawings relating to the aircraft. The incident information was only that available in the public domain from the NTSB docket.

Loss of Control (LOC) in general aviation has been a topic of extensive study and analysis in the United States and the European Union due to a long series of aircraft accidents in the past decades. The National Transportation Safety Board (NTSB) has identified over 1500 accidents in the traffic pattern involving LOC in general aviation aircraft between 1982 and 2015.
LOC has often been attributed to deficiencies in pilot training, and the typical recommendation to reduce the number of accidents is to provide further training in stalls and spins. The European Aviation Safety Agency (EASA) has performed research that demonstrates a large amount of traffic pattern accidents are concentrated in specific areas, such as flap deployment or retraction. To appropriately test the hypothesis that flap changes can be a contributor to LOC, a series of flight tests have been performed on four aircraft: PA32-260, PA28-161, PA28-180, and C 172-M. These flights were conducted at both forward and aft CG locations and in both wings level and banked conditions.
The case in which the pilot is distracted, either by looking outside for traffic, or simply attending to other matters in the cabin is assumed throughout this research. This assumption relates to James Reason’s chain of causation model, which states that an accident is caused by a series of failed defenses. Given this particular case, once the flap configuration change is applied, the flight test crew observed the behavior of the aircraft without the pilot intervening. The crew also recorded stick forces required to maintain trim airspeed after the configuration change.
Using on-board cameras and a non-intrusive Data Acquisition System, data were recorded on the aircraft’s pitch attitude, altitude, airspeed, and bank angle. Stick forces were recorded with a hand-held force gage.
The work presented in this thesis provides evidence that three of four aircraft tested, the deployment of flaps caused extremely dangerous pitch attitude and stick force changes, resulting in a loss of airspeed and consequential unusual attitudes. Tests were also conducted for go-around maneuvers, showing an increase in airspeed and sudden decrease in pitch attitude.
Finally, recommendations are expressed to reduce the effects of flap configuration change on longitudinal trim, providing recommendations for future research and a proposed revised version of Federal Aviation Regulations 23.143 and 23.145. Regulatory recommendations include the limiting of stick forces to 10 lbs. (one hand on rim) during flap configuration changes, with an added recommendation for the pitching direction to be nose-up (push force on controls) for flap retraction and nose-down (pull force on controls) for a flap deployment. The final intent of this thesis is to provide valuable information to aviation authorities, in order to reduce the amount of accidents due to loss of control in traffic patterns.

- by Tiziano Bernard, Ph.D.
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- Flight Test Engineering

The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the development of such requirements, useful guide lines are provided for test and evaluation of airborne laser systems including laboratory, ground and flight test activities.

- by Roberto Sabatini and +2
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- Electronic Engineering, Electronics, Flight Test Engineering, Photonics

The old flight instruments made by right brothers have only limited flight instruments that to only mechanical devices such as airspeed indicators, oil pressure gauge, fuel tank and single engine. The trend towards modern aircrafts have advanced features such as mentioned in this article all electronic instruments displays radar such as altimeter, attitude indicator, multiple engines displays of all parameters of aircraft. Indexing terms: fight instruments; pfd airspeed indicator; attitude indicator etc; INTRODUCTION Primary Flight Display (PFD) A PFD presents information about primary flight instruments, navigation instruments, and the status of the flight in one integrated display. Some systems include power plant information and other systems information in the same display. A typical primary flight display is shown in Figure 2-1. Primary Flight Instruments Flight instrument presentations on a PFD differ from conventional instrumentation not only in format, but sometimes in location as well. For example, the attitude indicator on the PFD in Figure 2-1 is larger than conventional round-dial presentations of an artificial horizon. Airspeed and altitude indications are presented on vertical tape displays that appear on the left and right sides of the primary flight display. The vertical speed indicator is depicted using conventional analog presentation. Turn coordination is shown using a segmented triangle near the top of the attitude indicator. The rate-of-turn indicator appears as a curved line display at the top of the heading/navigation instrument in the lower half of the PFD. Cross-Checking the Primary Flight Instruments The PFD is not intended to change the fundamental way in which you scan your instruments during attitude instrument flying. The PFD supports the same familiar control and performance, or primary and supporting methods you use with conventional flight instruments. For example, when using the primary and supporting method to maintain level flight, the altimeter is still the primary instrument for pitch, while the attitude indicator is a direct indicator and the vertical speed indicator provides supporting information. However, you need to train your eyes to find and interpret these instruments in their new formats and locations. Common Errors: Altitude Excursions and Fixation Pilots experienced in the use of conventional flight instruments tend to deviate from assigned altitudes during their initial experience with the PFD, while they adjust to the tape display presentation of altitude information. Another common error is the tendency to fixate and correct deviations as small as one to two feet at the expense of significant deviations on other parameters.

- by Roberto Sabatini
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- Aerospace Engineering, Flight Test Engineering, Aviation, Aerospace

C. Zavatson, 5/15/2013, rev D The longitudinal stability of the Lancair 360 has been a topic of discussion for a long time. The evolution of the design was at least partially influenced by longitudinal stability. The Lancair 360 has two horizontal tail configurations: The original "small" tail and the MKII tail. Much has been debated qualitatively regarding the handling qualities of each variant. The intent here is to present quantitative results from both analysis and flight tests that show the differences between the two configurations. Two approaches were used to determine the longitudinal static stability of N91CZ, a Lancair 360 with the MKII tail. First was a conventional analytical approach. The second was through flight test. The results are in excellent agreement. Some background is provided for each.

- by Christopher Zavatson
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- Flight Test Engineering

Midshipmen enrolled in EA417 were tasked with a limited scope evaluation of the flying qualities and performance of the Beechcraft Duchess (Be-76) airplane for the light utility mission. The test team was specifically charged with confirming manufacturer’s performance predictions, validating the suitability of the Pitot-static system, and determining the accuracy of the recently installed avionics. The aircraft met or exceeded all performance requirements, FAR specifications, and reasonable cruise attributes. The test team concluded that the aircraft was satisfactory to fulfill its missions of personal travel, short distance commercial transport, and multi-engine instruction. Future testing of climb performance, static stability, and dynamic stability will provide a fuller picture of the aircraft’s market suitability.

- by Geoffrey S DeSena
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- Flight Test Engineering

The HIFiRE-5 test article was an elliptic cone with a 2.5-mm nose radius and 2:1 aspect ratio and a 7-degree minor-axis half-angle. The vehicle was flown in April 2012. The upper stage of the sounding rocket failed to ignite, resulting in a peak Mach number of about 3 instead of the target of 7. Flight heat flux and pressure data (reduced from almost 300 thermocouples and 50 pressure transducers) have been compared to α- and β-dependent CFD results for pressure distribution, as well as laminar and turbulent heat-transfer results. Computations were performed at three time points in the ascent trajectory. At each time point, five values each of angle of attack and yaw, ranging from -5.0° to 5.0°, were computed. CFD pressures, normalized with p∞, were interpolated to the flight Mach numbers at specified times throughout the ascent and descent trajectories. At each flight time, α and β were estimated from measured pressure by determining the α-β combination that minimized the RMS difference between the measured and computed pressures. The vehicle attitude, as determined from measured pressure, was compared to the vehicle attitude derived from Inertial Measurement Unit (IMU) results for α and β from the flight. The two methods showed excellent agreement for the entirety of the ascent and reentry portions of the trajectory. A similar normalization of the laminar and turbulent heat transfer CFD results with St was compared to flight heat transfer measurements, and transition locations were inferred. Finally, a computational heat conduction analysis was made to verify assumptions inherent in the calculation of heat flux from temperature.

- by Roberto Sabatini
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- GPS Applications, Flight Test Engineering, GPS, GNSS

This paper examines airplane response to flap extension on four general aviation (GA) airplanes. The scenario involves a pilot flying in the traffic pattern who becomes distracted, abruptly extends flaps while looking outside the airplane, and fails to notice airspeed and pitch-attitude changes. In the Code of Federal Regulation (CFR) §23.143, the Federal Aviation Administration (FAA) requires no more than 50 pounds of pitch wheel force to arrest any un-commanded airplane pitch response [1]. The airplanes tested in this report had pitch forces less than 40 pounds. Despite satisfying the FAA requirement, data gathered in-flight showed a pitch-up to more than 30 degrees in 5 seconds after flap extension, subsequently causing airspeed to drop below stall speed for three of the airplanes. If the pilot did not compensate for this response with positive pitch inputs on the controls, the airplanes would have stalled. At traffic pattern altitudes, stalling an airplane can be fatal. The National Transportation Safety Board listed over 1000 accidents caused by loss-of-control in the traffic pattern between 1982 and 2015 [2]. Since GA airplanes don't carry flight data recorders, we don't know how many of those accidents may have involved stalls caused by un-commanded response after flap extension. From the data we gathered in-flight, it seems possible some were. To improve safety, airplane developers could interconnect flaps with the elevator, reduce horizontal tail size, or use a T-tail. The FAA should consider reducing the maximum pitch stick and wheel forces in CFR §23.143 to 10 pounds or less.

- by Tiziano Bernard, Ph.D. and +1
- •
- Flight Test Engineering

This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO 2 ) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO 2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO 2 /CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO 2 /CoO based catalytic converter are 93%, 89% and 82% for NO x , CO and HC emissions respectively. It is calculated that the TiO 2 /CoO based catalytic converter reduces 24%, 41% and 40% higher NO x , CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.

The extraordinary progress experienced in recent years in the field of lasers and infrared sensors, have led to the development of numerous active and passive electro-optical systems for civil and military aerospace applications. In the military domain, these developments have emphasised the need for flight instrumentation and ground control systems capable of supporting system test and training activities in operationally representative and wholly safe conditions at the ranges. This paper presents the main achievements of the PISQ Laser Test and Evaluation Range (PILASTER) research and development program. In particular, after a brief description of the PILASTER system requirements, the mathematical models and the hardware/software developed for system performance evaluation and eye-safety analysis are presented, including the novel techniques introduced for accurate measurement of laser energy and geometric characteristics in various weather conditions and operational scenarios (pointing accuracy, total energy, spot spreading, etc.). Additionally, the PILASTER sub-systems hardware and software architectures are introduced, followed by a brief overview of the laboratory, ground and flight test activities performed for the PILASTER formal verification and acceptance.

- by Roberto Sabatini
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- Aerospace Engineering, Remote Sensing, Atmospheric Science, Laser

This paper describes the early stage research of the Trajectory Recovery System (TRS). TRS provides directly perceivable and actionable aerodynamic performance and recovery information to a pilot in the event of an In-Flight Loss of Control (ILOC) event arising from exceedance of the aircraft's critical angle of attack (AOA), ILOC-S. Documented here, is the Human Centered Design (HCD) approach that was utilized to conceptualize, formalize, and select TRS design options. As a Joint Cognitive System (JCS), TRS architecture provides for fluid multi-agent interaction for optimum aerospace system vehicle performance. Therefore, the human-agent model for interaction that theoretically supports TRS is described. Prototyping history, from wireframe to a Wizard-of-Oz test bed, to an aerodynamically optimized algorithm animating a functionally flyable prototyping is reported.

- by Tiziano Bernard, Ph.D. and +1
- •
- Cognitive Science, Human Computer Interaction, Flight Test Engineering, Avionics

To protect telemetry from antenna masking during flight tests, two antennae must be used on-board.
To avoid phase opposition of the two transmitted signals at reception, frequency diversity has been
used for decades. However with spectrum auctions this technique is no longer compatible with the
requirement of higher bit rate. To overcome this issue, well-known modulation format like COFDM
may be used at the expense of power efficiency, with few constraints on antennae position. IRIG-106
standard proposed also SOQPSK-TG STC which is efficient both in power and in spectrum at the
expense of the antennae position. To demodulate this format a dual-trellis solution has been proposed based on XTCQM representation [1] with results very close to SISO as far as distance between
antennae does not exceed half bit delay. Therefore this decoding scheme is a hard decision scheme
and consequently is less power efficient when a FEC such as LDPC is used. In this paper a new decoding scheme will be presented with soft decision outputs to increase power efficiency, and with a
better tolerance to differential delay.

- by Alain Thomas
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- Flight Test Engineering, MIMO Systems, Digital Communication

This paper describes the design and development of an ecological display to aid pilots in the recovery of an In-Flight Loss of Control event due to a Stall (ILOC-S). The Trajectory Recovery System (TRS) provides a stimulus è response interaction between the pilot and the primary flight display. This display is intended to provide directly perceivable and actionable information of the aerodynamic performance state information and the requisite recovery guidance representation. In an effort to reduce cognitive tunneling, TRS mediates the interaction between pilot and aircraft display systems by deploying cognitive countermeasures that remove display representations unnecessary to the recovery task. Reported here, are the development and initial human centered design activities of a functional and integrated TRS display in a 737 flight-training device.

- by Tiziano Bernard, Ph.D.
- •
- Flight Test Engineering, Avionics, Avionics Engineering

This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO2) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO2/CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO2/CoO based catalytic converter are 93%, 89% and 82% for NOx, CO and HC emissions respectively. It is calculated that the TiO2/CoO based catalytic converter reduces 24%, 41% and 40% higher NOx, CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.

- by Roberto Sabatini
- •
- Control Systems Engineering, Aerospace Engineering, Remote Sensing, Laser

This study presents the development of an artificial neural network (ANN) that classifies from flight data, the flight turbulence level encountered by an aircraft. The input data is divided into three different groups that contributes for turbulence level classification: Flight Condition, Aerodynamic Configuration and Turbulence Measurement. There are two main methods applied at turbulence measurement, Power Espectrum Density of aircraft vertical acceleration signal and Discrete Gust calculated from inertial and anemometric aircraft data source. The ANN model developed is a Multilayer Perceptron which was trained with Levenberg-Marquardt Backpropagation algorithm, using flight test data of a specific aircraft prototype. The flight test data used at learning process consists of both recorded parameters and flight test crew subjective flight turbulence level classification. The most precise model developed (within the sixteen models proposed and analyzed) were trained also with Cross Validation method due to lack of samples that represents all possible characteristics of the flight turbulence phenomenon.

This paper presents new techniques for atmospheric sounding using Near Infrared (NIR) laser sources, direct detection electro-optics and passive infrared imaging systems. These techniques allow a direct determination of atmospheric extinction and, through the adoption of suitable inversion algorithms, the indirect measurement of some important natural and man-made atmospheric constituents, including Carbon Dioxide (CO2). The proposed techniques are suitable for remote sensing missions performed by using aircraft, satellites, Unmanned Aerial Vehicles (UAV), parachute/gliding vehicles, Roving Surface Vehicles (RSV), or Permanent Surface Installations (PSI). The various techniques proposed offer relative advantages in different scenarios. All are based on measurements of the laser energy/power incident on target surfaces of known geometric and reflective characteristics, by means of infrared detectors and/or infrared cameras calibrated for radiance. Experimental results are presented relative to ground and flight trials performed with laser systems operating in the near infrared (NIR) at 1064 nm and 1550 nm. This includes ground tests performed with 10 Hz and 20 KHz PRF NIR laser systems in a variety of atmospheric conditions, and flight trials performed with a 10 Hz airborne NIR laser system installed on a TORNADO aircraft, flying up to altitudes of 22,000 ft above ground level. Future activities are planned to validate the atmospheric retrieval algorithms developed for CO2 column density measurements, with emphasis on aircraft related emissions at airports and other high air-traffic density environments.

- by Roberto Sabatini
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- Aerospace Engineering, Laser Physics, Laser, Sustainable Development
- by Arthur Cropley
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- Flight Test Engineering
- by Graziano Terenzi
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- Augmented Reality, Flight Test Engineering, Aircraft Design