Browse Topic: Test procedures
This paper presents results of flight tests conducted on a coaxial ultralight helicopter. An automated flight test evaluation method is presented and exemplified through its application to steady horizontal flight. The results shown include pilot controls, helicopter attitude angles, power, thrust and torque distribution between the rotors, rotor harmonic thrust components, and teeter angles, along with their rotor harmonic components across varying flight speeds. This study focuses on the dependencies of these parameters on center of gravity position and sideslip angle.
This digital standard is a requirements extract of AS5127D Aerospace Standard Test Methods for Aerospace Sealants Methods for Preparing Aerospace Sealant Test Specimens. This file contains a general requirements extraction as well as files that are optimized for use with Doors Classic, Siemens Polarian, and PTC.
With recent advancements in the field of Advanced Air Mobility (AAM), including Electric Vertical Takeoff and Landing (eVTOL), Remotely Piloted Aircraft Systems (RPAS), and Unmanned Aerial System (UAS), it is beneficial to understand the impact of complex flow features on operations in urban and shipboard environments. Testing methods for studying these impacts, including simulated environments such as wind-tunnel flows and engineered equivalence tests, will need to be adapted to prepare for when the vehicles of interest are too large for the available testing facilities, and to permit low-cost alternatives for industry and government. This work demonstrates a development process that can be used to ensure the complex-flow-environment phenomena can be studied. First, this work illustrates the development of downdraft and turbulence flow types in a wind tunnel setting, and assesses the response of an M600 RPAS to these flows. Then, the same parameters are compared for a Mission Task Element (MTE) that was designed to challenge the RPAS in the vertical direction. Comparison of the two data sets provides insight into both the behaviour of RPAS in complex flows and the challenges of developing engineered equivalence tests.
The Sikorsky Boeing SB>1 DEFIANT is a technology demonstrator aircraft that was built under the Joint Multi-Role Technology Demonstrator (JMR TD) program to address the next generation performance requirements of the US Army Future Vertical Lift (FVL) initiative. During the development of the SB>1 DEFIANT technology demonstrator aircraft several manufacturing lots of gears were produced with a core hardness that was 10-30% below the minimum engineering requirement. The defect was not detected until a large population of gears was near completion. To prevent significant program cost and schedule impacts, a safe load capacity for the discrepant gears was determined via test. Dynamically loaded ground test articles for SB>1 DEFIANT technology demonstrator aircraft began qualification testing with the low hardness gears. The low hardness issue, root cause, and test method to establish a safe operating load limit are discussed.
This standard describes the accepted methods used for preparing aerospace sealant test specimens for qualification and quality conformance or acceptance testing. AS5127/1 and AS5127/2 are to be used in conjunction with this document and the applicable AMS specifications.
This paper presents the preliminary results of the recent whirl flutter wind tunnel test campaign performed within the Advanced Testbed for TILtrotor Aeroelastics (ATTILA) project. The Froude-scale ATTILA testbed consists of a semi-span wing with powered tip-mounted proprotor reflecting the proprietary design of the Next Generation Civil TiltRotor (NGCTR). An overview of the ATTILA testbed, wind tunnel test procedures, team organisation and preliminary flutter results are presented. In line with pre-entry dynamic characterization tests, the wind-on test activities in the DNW Large Low-speed Facility (LLF) revealed notable force-dependent nonlinearity in the modal characteristics of, particularly, the wing torsion mode. Further dimensionality was added by early observations that damping in the rotor gimbal degree of freedom, attributed to stiction in the blade pitch mechanism, had the potential to substantially contribute to the damping of the fundamental wing-pylon modes. Nevertheless, the parallel exploitation of multiple monitoring and online modal estimation methodologies enabled a robust identification and safe test progression. The critical flutter mode was found to be configuration dependent, with the wing chord bending mode generally being marginally stable throughout most of the wind speed range, and the wing torsion mode displaying a sharp trend towards negative damping at higher speeds. Despite technical challenges, valuable test data was gathered to advance the experimental methods and support validation of the numerical tools used to obtained clearance for high-speed flight testing of the full-scale NGCTR Technology Demonstrator.
Launch, recovery, and deck handling operations are among the most challenging tasks in the deployment of fleet piloted and unpiloted air vehicles on board of air capable ships. In today's long-lead acquisition process, some existing devices are installed on new ship platforms for which the air vehicle was not initially designed. As part of the Navy deployment process, a ship suitability assessment is conducted in the form of Dynamic Interface (DI) testing. DI testing evaluates all aspects of shipboard helicopter including suitability, compatibility, adequacy, effectiveness, safety of air vehicle shipboard Flying Qualities and Performance (FQ&P), aviation support facilities and procedures for all ship-based aircraft types. With monohulled rudder/screws steered legacy vessels, certain seakeeping and turbulent boundary properties have open-ocean performance similarities. When faced with a deployment target ship producing different ship properties, a systematic approach to adapt to the new environmental condition is devised. A significant example involves the deployment of air vehicles (both piloted and unpiloted) on-board LCS class vessels where large, unexpected roll oscillations, coupling with rapid motions of the stern, are recorded. These unusual deck responses have been traced to shipboard operational characteristics which do not relate to the seaway alone. The implications for air vehicle operations encountering seemingly random large motions further underscores the need for an accurate definition of the ship's dynamics and, possibly, refined models able to predict steep motions anticipating the onset of excessive movements. In this paper we describe a new instrumentation with the goal to predict ship motions conditions with sufficient forecasted time (over a minute) to launch, recover and complete other motion sensitive tasks regardless of the seaway. The fundamental concept is to measure remote sea surface profiles to predict the future wave forces acting upon a vessel as a function of the approaching air vehicle. The final objective is to expand ship operating deck limits to approximately Sea State 6+. This will allow the air's vehicle operator to have a more complete deck information and ship behavior. This article describes the common test procedures being developed at Fincantieri to define the deck behavior with the least air vehicle modifications. Enhanced dynamic interface testing is designed to better understand how the new ship classes affect the deck environment. The enhanced trial methodology test results clearly characterize essential aspects of the ship responses to the maritime climate and its impacts on air vehicle launch and recovery.
ABSTRACT This paper presents the preliminary results from the experimental study of the aerodynamic characterization of a novel dissimilar coaxial rotor concept with reduced rotor-rotor interaction. The performance of dissimilar coaxial rotor concept is compared with existing rotor configurations such as conventional single main-rotor tail-rotor and regular coaxial rotor. The performance measurement is carried out using a small scale coaxial hover test stand facility setup for this purpose. The hover performance of different rotor concepts namely conventional, regular coaxial and dissimilar coaxial rotors are compared as anti-torque mechanisms with same baseline rotor by comparing their power loading. The inter-rotor spacing between coaxial rotors is kept constant at 15% of the rotor radius. The dissimilar coaxial rotor appears to be a promising solution for development of high efficiency hovering rotor system for high thrust condition. From the tests conducted on a main rotor of 0.415 m radius operated at 1000 RPM, it is established that the dissimilar coaxial rotor system consistently shows higher power loading than the conventional rotor (especially at high thrust condition) as well as the coaxial rotor system. To achieve maximum benefits from the dissimilar coaxial rotor system, the anti-torque rotor in the dissimilar rotor pair must be spun at 50% or 40% of the main rotor RPM. The effect of the cross-section shape of the blade-hub attachment (root cutout) plays a significant role in reducing the profile power loss of the anti-torque rotor of the dissimilar coaxial rotor. In the current study, three different shapes were compared and the elliptical cross-section shape was observed to give best performance.
A use-case was conducted in Montréal in the summer and fall of 2023 to measure urban airflow characteristics using a small Remotely-Piloted Air System (sRPAS). The goal of the study was to acquire urban airflow data in a real environment in order to validate urban airflow characteristics from laboratory-scale testing conducted previously. The use-case took place in the downtown core of Montréal and involved flights from two hospitals to a variety of other buildings. The sRPAS was instrumented with an airflow measurement system. Fixed rooftop anemometer stations were also installed on top of buildings along the flight paths to measure urban airflow at altitudes within close proximity to rooftops. The study generated a valuable data set for characterizing sRPAS operations in urban environments. A number of operational challenges were experienced including the difficulty associated with visual line of sight operations with an urban backdrop, avoiding conditions that could lead to loss of command and control link, and the need to monitor electromagnetic interference during flight operations. The use-case produced evidence of the impact of urban airflows on the stability and response of sRPAS. High wind speeds and turbulence intensities were found in the urban flow field of Montréal. The sRPAS use-case results were used to validate wind-speed and turbulence characteristics from laboratory-scale testing on Canadian cities.
In recent years, testing and validation have become crucial in the automotive ECU design process. Requirements of security and functional safety in addition to ever increasing connectivity have led to added complexity in the testing process. Testing is not only a mandatory base practice across the entire product development lifecycle, it also has a direct impact on product quality.
This SAE Recommended Practice defines a procedure for determining the adhesion strength characteristics of heat-cured metal bonding adhesives subjected to induction heating.
This SAE Recommended Practice shall be used to determine the peel strength achieved by an adhesive when used to bond various decorative, flexible substrates such as cloth supported vinyl or carpet, to rigid (steel), semi-rigid (SMC plastic), or other similar substrates.
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