The Use of a Lidar Forward-Looking Turbulence Sensor for Mixed Compression Inlet Unstart Avoidance and Gross Weight Reduction on a High Speed Civil Transport
Soreide, David and Bogue, Rodney K. and Seidel, Jonathan and Ehernberger, L.J. (1997) The Use of a Lidar Forward-Looking Turbulence Sensor for Mixed Compression Inlet Unstart Avoidance and Gross Weight Reduction on a High Speed Civil Transport. Technical Report NASA TM-104332, Research Engineering, NASA Dryden Flight Research Center.
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Abstract
Inlet unstart causes a disturbance akin to severe turbulence for a supersonic commercial airplane. Consequently, the current goal for the frequency of unstarts is a few times per fleet lifetime. For a mixed-compression inlet, there is a tradeoff between propulsion system efficiency and unstart margin. As the unstart margin decreases, propulsion system efficiency increases, but so does the unstart rate. This paper intends to first, quantify that tradeoff for the High Speed Civil Transport (HSCT) and second, to examine the benefits of using a sensor to detect turbulence ahead of the airplane. When the presence of turbulence is known with sufficient lead time to allow the propulsion system to adjust the unstart margin, then inlet unstarts can be minimized while overall efficiency is maximized. The NASA Airborne Coherent Lidar for Advanced In-Flight Measurements program is developing a lidar system to serve as a prototype of the forward-looking sensor. This paper reports on the progress of this development program and its application to the prevention of inlet unstart in a mixed-compression supersonic inlet. Quantified benefits include significantly reduced takeoff gross weight (TOGW), which could increase payload, reduce direct operating costs, or increase range for the HSCT.
| EPrint Type: | NASA Technical Memorandum |
|---|---|
| Keywords: | SR-71 aircraft, DC-8 aircraft, Inlet aircraft, Alarm systems, Aircraft instrumentation, Lidar, High Speed Civil Transport, Laser optical radar |
| Subjects: | Aircraft/Project: DC-8 (01 - 09) Aeronautics: (07) Aircraft Propulsion And Power Aircraft/Project: SR-71 Blackbird |
| ID Code: | 138 |
| Deposited On: | 08 June 2004 |
| Additional Information: | 17 pages. Presented at the 33rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, July 6–9, 1997, Seattle, Washington |
