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Optical Air Data System (OADS)

Description:

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics

 

OBJECTIVE: The objective of this project is to test and evaluate the accuracy of Optical Air Data Systems and determine their suitability and utility as flight-test-specific instrumentation and primary aircraft equipment. The proposed effort is focused on maturing the technology to be able to provide additional measurements of ambient temperature, density, angle of attack and sideslip as well as true airspeed on high performance aircraft in regimes faster than the speed of sound.

 

DESCRIPTION: All aircraft rely on accurate air data measurements to either be used by the pilot, or to be used by more complicated aircraft with flight control systems. These air data measurements typically include altitude, airspeed, ambient temperature, angle of attack (AoA), and angle of sideslip (AoS). Pilots will target altitudes and airspeeds for tasks such as takeoff, approach, and landing. Being at the correct speed ensures safe handling characteristics while being at the correct altitude ensures safe clearance from the ground and obstacles. Flight control systems will schedule inputs based on the flight computer's understanding of the aircraft's airspeed, AoA, and AoS. Whether used by the pilot or the flight control computer, accurate air data measurements are essential to the safe operation of aircraft.

 

Typical air data systems rely on combinations of probes that extend from the aircraft and flush static ports. Unfortunately, these systems cannot measure the ambient conditions because either the probes, or the aircraft itself distorts the flow. So providing accurate air data measurements by existing means requires careful consideration during the design phase. Even with careful design considerations, the overall flight test campaign still requires costly and dedicated flight test time and techniques to determine the errors associated with their installation.

 

Optical Air Data Systems (OADS) use lasers to interrogate the air mass without physically disturbing the flow. OADS effectively provide the necessary information free from errors associated with traditional pitot-static or flush air data systems. Several efforts have demonstrated this capability, but only in subsonic environments and none have actually compared the accuracy of OADS to currently accepted methods. Aircraft that travel in the transonic to supersonic regimes create larger disturbances and OADS would have to interrogate packets of air across a shock front. 

 

Initial evaluations of overall accuracy will be performed with the OADS integrated into a flight test pod installed on a specially modified F-16 test aircraft, known as a Pacer, that can make precise air data measurements. Air data measured by the OADS would be compared to the solution provided by the F-16 Pacer. On subsequent test efforts, the OADS would be integrated into a larger bomber type aircraft for evaluations of suitability and utility as flight-test-specific instrumentation and as primary aircraft equipment replacing traditional air data systems.

 

PHASE I: This is a Direct-to-Phase-II (D2P2) topic, no Phase I awards will be made because of this topic. To qualify for this D2P2 topic, the Government expects the Offeror to demonstrate feasibility by means of a prior “Phase I-type” effort that does not constitute work undertaken as part of a prior SBIR/STTR funding agreement.  Offerors are expected to provide a white paper providing a comprehensive feasibility assessment that outlines the technical viability of using Optical Air Data Systems (OADS) for flight-test-specific instrumentation and primary aircraft equipment at speeds more than the speed of sound and at altitudes up to 50,000 feet.

 

This assessment should address the suitability of the systems for accurate air data measurements and their potential integration into different aircraft platforms. Additionally, I expect Accuracy Testing, where the contractor conducts initial evaluations of the overall accuracy of the OADS as implemented in wind tunnel environments. Offerors should specify the testing methodologies and procedures to ensure precise air data measurements during the evaluations.

 

Furthermore, Data Analysis is essential, and I anticipate the Offerors to conduct a thorough analysis and provide meaningful conclusions about the accuracy, suitability, and utility of the OADS as flight-test-specific instrumentation and primary aircraft equipment. Lastly, I also expect a rugged integration of the OADS into the flight test pod, which will be installed on a specially modified F-16. The Offerors should then demonstrate how the system can effectively be integrated into several aircraft design structure and predict its performance in real-flight scenarios.

 

PHASE II: The proposed effort is focused on maturing the technology to be able to provide additional measurements of ambient temperature, density, angle of attack and sideslip as well as true airspeed on high performance aircraft in regimes faster than the speed of sound. As a result, the Phase II Period of Performance objectives:

1.) Integrate Optical Air Data System into a flight test pod to be carried on an F-16.

2.) Collect flight test data used to evaluate the Optical Air Data System against the Air Force Test Center's specially modified Pacer F-16.

3.) Evaluate the suitability and utility of Optical Air Data Systems to serve as a flight-test-unique truth source of air data measurements.

4.) Evaluate the suitability and utility of Optical Air Data Systems to replace the primary air data system in lieu of traditional pitot-static or flush air data system. Success criteria includes gathering information on the measurement of the following five air data measurements throughout the flight envelope of the flight test pod as installed on an F-16 and through the flight envelope of the large bomber type aircraft.

 

Air Data Measurements:

1.) True Airspeed

2.) Ambient Pressure

3.) Ambient Temperature

4.) Angle of Attack

5.) Angle of Sideslip

As integrated on to the F-16, operating parameters are from zero to 50,000 feet Pressure Altitude, and zero airspeed up to 1.2 Mach Number. The operating parameters for the large bomber type aircraft will depend on the platform selected.

 

PHASE III DUAL USE APPLICATIONS: Phase III would transition this type of hardware to be the primary means of measuring air data parameters on aircraft to replace traditional air data installations. Phase II is expected to increase the TRL of this technology to a 7-8 prior to entrance to Phase III. Stealth aircraft and hypersonic platforms would be able to eliminate thousands of hours of design and development on flush air data systems typically used in these applications. Additionally, these aircraft would be able to eliminate required dedicated flight test efforts to calibrate said systems. Additional commercial applications extend to airliners for detecting Clear-Air-Turbulence (CAT). CAT is not typically associated with weather phenomena and is much more difficult to detect and avoid. The National Transportation Safety Board reported 197 turbulence-related accidents between 2009 and 2018, all caused serious injuries. Nearly 30 percent of these accidents were caused by CAT. Optical Air Data Systems can potentially be used to detect CAT with enough advanced notice to avoid the area and prevent accidents.

 

REFERENCES:

  1. NASA/TP-2004-210735, Optical Air Flow Measurements in Flight, Bogue, R. K., and Jentink, H. W., National Aeronautics and Space Administration Dryden Flight Research Center, Edwards AFB, California, December 2004.;

 

KEYWORDS: Optical Air Data System

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