NASA Langley Research Center, Linda Fitzgerald, MS 144 Hampton, Va. 23681-0001

A -- WAKE VORTEX MEASUREMENT TECHNIQUES POC Linda P. Fitzgerald, Industry Assitance Office (804) 864-2461. The NASA Langley Research Center (LaRC) is investigating techniques for remotely detecting, tracking and measuring the strength of wake vortices generated by aircraft during landings and take-offs. Aircraft in flight create swirling masses of air behind them (in their wake) which are called trailing vortices or wake vortices. They can resemble a pair of horizontal tornados which appear to originate at each wing tip and extend back behind the aircraft. Initially they may extend as nearly straight lines but eventually become very wavy and three dimensional as instabilities develop when the vortices interact with turbulence in the atmosphere. The lifetime of a vortex may vary from tens of seconds to a few minutes depending the size of the aircraft that generated it and the state of the atmosphere. Wind speeds near the center of the vortex may approach 100 meters/sec initially for a strong vortex and may be a small fraction of that for an older vortex. However, the magnitude of the maximum wind speed does not determine the strength of the vortex or the associated hazard. One method of measuring the strength relies on measuring the windspeeds of a region 20-30 meters around the center of the vortex where windspeeds may be just greater than the ambient windspeed. Therefore, there may be different requirements for detecting/tracking and for strength measurements. LaRC is conducting a survey to identify sensing instruments which have the potential for measuring information about the location and strength of these wake vortices. Identification of suitable sensing instruments may lead to field validation testing and subsequent development of a demonstration sensor system for use with the Aircraft Vortex Spacing System (AVOSS) currently being developed by LaRC. It would be desirable to identify a single instrument capable of detecting, tracking and measuring the strength of wake vortices, from the outer marker to touchdown and on all airport runways, however, most instruments have limitations imposed by factors such as varying weather conditions and the distance to the vortex. Instruments having more limited capabilities are also of interest since information provided by one instrument could conceivably augment the data provided by another instrument and together provide a better measurement of the vortex. In this manner, a ''suite'' of instruments could be deployed to detect, track and measure the vortices at each runway from the outer marker to touchdown provided the instruments are economical to acquire and maintain. The purpose of this notice is to solicit new and innovative instruments for wake vortex detection. Parties with instruments having the potential for wake vortex detection/tracking and/or strength measurement are invited to submit a description of their instrument and a proposed deployment concept for field data collection and subsequent analysis to validate the instrument capability to measure wake vortices (total length of descriptive material not to exceed five pages). This information should be submitted within three weeks from the date of publication of this announcement. Respondents determined by NASA Langley Research Center to have new and innovative instruments may be invited to participate in wake vortex detection and data collection activities being conducted jointly by the Volpe National Transportation Systems Center (Volpe Center) and LaRC at John F. Kennedy International Airport during the fall of 1996 or the spring of 1997. Invitations may be issued without further advertisement. Any such invitations will be accompanied by invitational travel orders to each selected respondent to cover travel and per diem costs of two personnel for a test period of approximately two weeks in duration. LaRC and the Volpe Center will provide infrastructure support such as cabling and trenching for power and data lines, environmentally controlled shelter(s) and power for data collection and storage instrumentation, portable generators for remote power, etc. for the duration of the test. All other materiel, labor, and transportation costs associated with conducting the test shall be borne by the selected respondent(s). LaRC and VNTSC will also provide host support for obtaining approval of the FAA and the JFK Airport Authority for each selected respondent's test operations at JFK and for scheduling of test activities. It is LaRC's intent that all sensor testing be conducted at the same time on the same vortices. In return for this opportunity, respondents will be required to sign a Memorandum of Agreement with LaRC which requires that copies of the results of all instrument testing, data collection, and post processing of the data be provided to LaRC and VNTSC for review and analysis. All company proprietary rights will be maintained. If government review and analysis of the data indicates potential for further development, any such development will be conducted following establishment of a formal contract with the respondent. Selection of a respondent for participation in field tests at JFK International Airport will in no way obligate the government to fund development of the concept(s). Please submit concept descriptions meeting the above guidelines to NASA Langley Research Center, Hampton, VA 23681-0001, Attn: Ben C. Barker, Mail Stop 474, (804) 864-7064. This synopsis is for information and planning purposes only and does not indicate a commitment by the Government nor will the Government pay for information solicited. In responding reference SS264. (0232)

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