Browse Topic: Performance tests
This paper describes the electromagnetic noise mitigation on the Maryland Tiltrotor Rig (MTR) and presents its first hover test results. The primary source of noise was found to be pulse width modulation associated with the motor controller. Due to this noise, testing was limited to unpowered, freewheeling cases. To solve the noise problem and allow powered testing, three hardware filters were integrated into the power and data systems. A complementary digital filter was also used. With the filtering solution in place, hover tests were carried out to high collectives of 30◦and blade loadings of 0.2. The test data was assessed using blade element-momentum theory predictions.
T-625 helicopter, created by the Turkish Aerospace Helicopter Group, serves as a light utility multi role helicopter. It is powered by a pair of CTS800-4AT turboshaft engines, which were developed by the Light Helicopter Turbine Engine Company (LHTEC). This paper presents aspects of performance characteristics for air intakes, exhaust system and engine vents in powerplant integration of the T-625 helicopter, together with the results of engine installed performance flight test campaign, which are performed to determine the engine installation losses.
Aircraft with small speed-controlled propellers are becoming increasingly popular. This is conspicuous in the commercial sector, but also evident in the defense sector. Proof of the latter is the Army's Air Launched Effects (ALE) program, which aims to develop foldable, tube-launched Unmanned Aerial Systems (UAS). Such aircraft will likely use small speed-controlled folding propellers, which have unique geometry and limited publicly available data making it difficult to characterize their performance. This paper concerns performance testing of a small speed-controlled folding propeller in the U.S Army's 7- by 10-foot Wind Tunnel at NASA Ames Research Center, utilizing a new test rig that aerodynamically isolates a propeller's blades. The results of the test are presented, which include thrust and efficiency measured at various pitch angles, rotational speeds and wind speeds. Useful and expected trends are identified in the data, such as the peak efficiencies increasing with increased RPM, wind speed and blade pitch.
The subject of the research in this paper is to achieve longer and more reliable loss of lubrication (LoL) performance. The research developed the computational thermal analysis model including airflow inside and outside transmissions to predict thermal behavior under LoL. And the research conducted the LoL performance test using the modified BK117D2 (EC145T2) main transmission optimally designed with the computational analysis. Data measurement during the test included temperatures of rotating components such as gears and bearings, temperature distribution on the gear teeth, and airflow speeds and heat fluxes around the transmission in order to analysis the test result. The test procedure was according to the EASA new rule, which has severer test condition than the past rule. The test result shows longer LoL performance than the past test of the BK117D2 main transmission. And the computational analysis model was validated with the measured data. Then, the failure cause and possible future improvements were investigated based on the measured data and the analysis model. Finally the research concluded the modifications on the transmission, the computational analysis model and the measured data are able to make LoL performance longer and more reliable.
The command inputs selected for system identification (SYSID) are dictated by numerous factors, some of which include: 1) The frequency range of interest; 2) The capability of the system to sustain the inputs; 3) The capability of the system to remain ‘agnostic’ to future inputs. When the elements comprising, the system being identified are all electro-mechanical, frequency sweeps, sum-of-sines, and impulsive inputs are standard identification techniques. However, when human manual control becomes an element of the system, the second and third factors are key considerations. Sum-of-sines (SOS) has been used extensively for identifying human control dynamics as it provides an input that is perceived by the pilot as random and focuses power at discrete frequencies. A disadvantage of SOS is the attentional demand it requires from the human operator, which limits the duration of an identification run to typically around one minute. This in turn constrains the lowest frequencies that can be identified, and multiple consecutive runs can lead to operator fatigue and performance degradation. Discrete inputs such as ramps have been employed with human-in-loop testing, but only with regard to Handling Qualities and performance testing. This work examines discrete inputs as a method for human-in-loop SYSID. An experiment was conducted using two terrain profiles: 1) Pop-up (POP), where four mesas (hills) of varying height, slope, and plateau length were unevenly spaced on flat terrain; 2) Sum-of-sines (SOS), where the terrain was comprised of the sum of eleven non-harmonically-related sine waves, so that the contour was perceived as varying randomly. The task for both terrain types was to maintain 20 feet above the ground using pitch (airspeed was fixed at 35 knots) for each run. Bedford workload ratings were collected after each run. Both terrain profiles produced approximately the same open-loop frequency responses, and their coherences were not significantly different. However, the Bedford ratings showed the POP profile was significantly easier to execute than SOS. The POP technique thus presents a less demanding, more appealing, and potentially more consistent way for eliciting frequency information relating to pilot gain, stability, and time delay.
This Recommended Practice can apply to both Original Equipment Manufacturer and Aftermarket route-guidance and navigation system functions for passenger vehicles. The methods apply only to the presentation of visual information and the use of manual control inputs to accomplish a navigation or route guidance task. They do not apply to visual monitoring tasks which do not require a manual control input, such as route following. Voice-activated controls or passenger operation of controls are also excluded.
In this paper, a method is proposed to determine the flight envelope limitations for steady forward flight with the purpose of performing a flight envelope expansion. First, the rotary wing system is analyzed. In this paper, an intermeshing rotor configuration, a SwissDrones Dragon 50, is used to demonstrate the approach. Next, relevant limitations of the forward flight are reviewed and analyzed with the help of the Helicopter Overall Simulation Tool (HOST). From this analysis, relevant measurement concepts are derived and consequently measurement parameters are defined. Following, a flight test instrumentation is developed including a small-scale rotor telemetry. This instrumentation is tested in flight test. The corresponding flight test program is briefly discussed. It consists of tethered hover flight and a level flight performance test. The results of these flight tests are discussed and used to determine the flight performance limitations encountered.
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