DI-SESS-82458

Inlet Compatibility Substantiating Data Report

Specifies the format and content for contractors to report inlet design, performance, and operability data used to evaluate air vehicle airworthiness and integrated airframe/inlet/engine compatibility.

Approval DateDecember 2, 2024

AMSC NumberF10514

Preparing Activity11 (AFLCMC/EZFT)

Project NumberSESS-2025-004

OPR—

DTIC ApplicableNo

GIDEP ApplicableNo

Limitation—

Applicable Forms—

Approval Limitation—

Form Version—

DID Formatfree_text

963C CompliantYes

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

Supersedes

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Description & Purpose

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Application & Interrelationship

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Use & Relationship

The Inlet Compatibility Substantiating Data Report (SDR) will be used to obtain inlet design, performance, and operability information from contractors for evaluating air vehicle airworthiness by government personnel. Inlet compatibility substantiating data includes computational aerodynamics models/results, sub-scale wind tunnel test results, full-scale ground and flight test results, and other related data. The data and results in the inlet compatibility SDR directly contribute to the engine stability audit and are crucial for determining integrated airframe/inlet/engine compatibility.

This Data Item Description (DID) contains the format, content, and intended use information for the data product resulting from the work task described in the contract Statement of Work.

Preparation Instructions

1Reference documentsThe applicable issue of the documents cited herein, including their approval dates and dates of any applicable amendments, notices, and revisions, shall be as specified in the contract. The following references are made available at https://www.sae.org/standards/ SAE ARP1420 Gas Turbine Engine Inlet Flow Distortion Guidelines SAE AIR1419 Inlet Total Pressure Distortion Considerations for Gas Turbine Engines SAE AIR5686 A Methodology for Assessing Inlet Swirl Distortion SAE AIR5687 Inlet/Engine Compatibility - From Model to Full Scale Development SAE AIR5866 An Assessment of Planar Waves SAE AIR5867 Assessment of the Inlet/Engine Total Temperature Distortion Problem SAE ARP6420 Guidelines for Characterization of Gas Turbine Engine Total-Pressure, Planar-Wave, and Total-Temperature Inlet Flow Distortion The following references are made available at https://quicksearch.dla.mil/ DI-SESS-82328 Computational Aerodynamics Analysis Results DI-SESS-82361 Acquisition and Sustainment Data Package (ASDP) Technical Report MIL-HDBK-831 Preparation of Test Reports MIL-HDBK-310 Global Climatic Data for Developing Military Products

2FormatUnless otherwise specified below, inlet-compatibility substantiating data shall be either in electronic document format, such as portable document format (PDF), the schema required by the acquirer's digital engineering environment, or the supplier's preferred format. Content of electronic documents must be legible to include all text, figures, and text/labels within figures.

3ContentInlet compatibility substantiating data shall include details of any physical, computational, or analytical models needed for a third-party assessment of the accuracy of the results. The source of each data item shall be identified. For data determined analytically, the complete set of equations with a sample problem shall be presented. For computational aerodynamics models, follow DI-SESS-82328. Enough information must be provided to understand the propulsion system design and the impact of inlet performance and operability on engine stability throughout the aircraft flight envelope. Unless otherwise specified, all items below should be quantified for Mach numbers, angles of attack, angles of side slip, and Reynolds numbers across the aircraft flight envelope, including static conditions. Information affected by non-standard atmosphere types will be provided for STD, HOT, and COLD days per MIL-HDBK-310. Inlet compatibility data shall include:

3.1General data

3.1.1Schematic and narrative description of internal aero surfaceswith dimensioned detailed scale drawings or a digital model including:

3.1.1.1Inlet lips, highlight, cowl and forebody geometries

3.1.1.2Airframe forebody protrusions that may impact inlet compatibility

3.1.1.3Inlet capture area, throat area, and maximum diameter

3.1.1.4Diffuser shape, length, and area ratio as a function of fuselage station

3.1.1.5Inlet location on aircraft fuselage

3.1.1.6Inlet variable geometries, sensing/feedback mechanisms, and schedulingas a function of Mach number and altitude.

3.1.1.7Secondary flow path geometry and maximum flow rates

3.1.1.8Bleed, bypass, auxiliary inlet doors, blow-in doors, ECS, vortex generators, strakesboundary layer removal schemes and any other passive/active flow control devices.

3.1.2Integrated airframe/inlet/engine maximum angles of attack and sideslipas a function of Mach number over the full aircraft speed range, including effective sideslip angle for the largest required crosswind at takeoff/static conditions and the largest required in-flight gust load.

3.2Details on any Computational Aerodynamics (CA) predictions of inlet performance/operabilityincluding vision system, sub-scale wind tunnel model, or full-scale ground test. Delivery of CA predictions shall be in accordance with DI-SESS-82328.

3.3Details of subscale inlet wind tunnel tests

3.3.1Model design, model configurations, and model installation in facility

3.3.2Facility capabilities and limitations

3.3.3An as-executed test matrix

3.3.4Differences between model geometry and vision system (or production system) geometry

3.3.5Model instrumentation

3.3.5.1Forebody and inlet duct pressure measurement types and location

3.3.5.2Aerodynamic Instrumentation Plane (AIP) orientation, location, and distributionof any steady-state, dynamic, or swirl probes.

3.3.5.3Instrumentation manufacturer, type, and dynamic range

3.3.5.4List or schematic of locations of failed instrumentationrun numbers where instrumentation was failed, and correction/substitution method.

3.3.5.5Length/size of pressure tubing and analysis of any associated pressure lags

3.3.5.6List of instrumentation names and data file typesfor use in post-test data processing.

3.3.6Mass flow control system, calibration, and instrumentation

3.3.7Data acquisition and data processing

3.3.7.1Data acquisition system and sampling rate

3.3.7.2Low-pass and high-pass filter types and implementation methodsFilters should include 1/2 to 1-per-rev engine-order filter scaled to wind tunnel geometry, anti-alias filters, A/D filters, and noise filters both analog and digital.

3.4Details of inlet-engine compatibility flight test

3.4.1Inlet, AIP, and engine instrumentation

3.4.1.1Forebody, inlet duct, fan duct, core duct pressure and temperature measurement location, type, and range

3.4.1.2AIP number, orientation, location, and distribution of instrumentationInclude any differences between ground and flight test AIP rakes.

3.4.1.3List of instrumentation names and data file typesfor use in post-test data processing.

3.4.1.4List or schematic of locations of failed instrumentationrun numbers where instrumentation is failed, and correction/substitution method.

3.4.1.5Length/size of pressure tubing and analysis of any associated pressure lags

3.4.2Data acquisition and data processing

3.4.2.1Data acquisition system and sampling rate

3.4.2.2Low-pass and high-pass filter types and implementation methodsFilters should include 1/2 to 1-per-rev engine-order filter scaled to wind tunnel geometry, anti-alias filters, A/D filters, and noise filters both analog and digital.

3.4.2.3Any differences between ground/flight methodsfor distortion descriptors, data processing/screening, and engine stability audit methodology.

3.4.3Comparison of flight test inlet data with corresponding subscale inlet dataat the closest test condition or interpolated conditions from wind tunnel.

3.5Inlet recovery and distortion analysis resultsfrom subscale wind tunnel test, full-scale ground test, and flight test. Distortion descriptors shall be provided in the engine manufacturers index system with equations describing both radial and circumferential directions.

3.5.1Process of combining AIP steady-state and dynamic total pressure measurementsprior to distortion descriptor calculations.

3.5.2Distortion descriptor calculations

3.5.3Details on peak-instantaneous dynamic distortion screening method

3.5.4Methodology to combine distortion intensities and engine sensitivitiesto produce an estimate of the loss in stability pressure ratio of each compression component in accordance with SAE AIR1419 and SAE ARP1420.

3.5.5Inlet planar wave (subsonic) and buzz (supersonic) regionsincluding the screening parameter, limits, and airflows at which the limit is crossed as a function of Mach number and vehicle attitude.

3.5.6Supersonic/hypersonic inlet unstart and restartas a function of airflow, Mach number and vehicle attitude.

3.5.7Ground-to-flight scaling increments for inlet recovery and distortionand description of methodology used in accordance with SAE AIR 5687.

3.5.8Inlet recovery, steady-state distortion descriptors, peak instantaneous distortion descriptorsand resulting loss in engine stability pressure ratio (for fan and core) as a function of airflow, Mach number, angle of attack, angle of sideslip, and Reynolds number.

3.5.9Effects of icing of inlet recovery, steady-state distortion, and dynamic distortionwith/without de-icing systems if the aircraft will fly in icing conditions.

3.5.10Fan to core distortion transfer characteristicsas a function of corrected airflow.

3.5.11Doghouse plots of steady-state and peak-instantaneous distortion descriptorscompared to engine limits for each Mach number regime.

3.5.12Contour plots of AIP steady-state recoveries and dynamic RMSfor relevant worst-case distortion conditions including static conditions and including edges of the doghouse limits in both circumferential, radial directions.

3.5.13Pressures in the inlet duct or forebodyas a function of fuselage station and test conditions.

3.5.14Hammershock pressure analysis across the flight envelopeto ensure engine stall does not result in failed inlet hardware.

3.5.15Temperature distortion from hot gas ingestion, duct heat transfer, de-icing systems, or reverse inlet secondary flowsin accordance with SAE AIR5867.

3.5.16Swirl distortion descriptorsin accordance with SAE AIR 5686 or analysis proving that swirl is mitigated using fan inlet guide vanes.

3.5.17Deterministic fan and core stability auditsshowing the impact of peak instantaneous dynamic distortion, temperature distortion, and swirl distortion on fan and core available stability margin.

References

SAE Standards https://www.sae.org/standards/

DLA Quick Search https://quicksearch.dla.mil/

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