LANGLEY RESEARCH CENTER - SUAVELab TEAM June 26, 2008 Michael J. Logan, P.E. Head, Small Unmanned...

LANGLEY RESEARCH CENTER - SUAVELab TEAM

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June 26, 2008

Michael J. Logan, P.E.Head, Small Unmanned Aerial Vehicle Laboratory

(SUAVELab)NASA Langley Research Center

NASA SMALL UNMANNED AIR VEHICLE LABORATORY (SUAVELab)

TOPICS FOR CERTIFICATION WORKING GROUP


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AGENDA

• SUAVELab GUIDELINES– Design– Pre-flight testing

• NASA LANGLEY ASRB– Airworthiness and Safety Review Board

• FTOSR– Description of Flight Test Operation Safety Report

– Hazards Analysis

• OTHER INFO– DoD Unmanned Systems Guidelines & Safety Precepts


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SUAVELabSUAVELabGuidelinesGuidelines


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• What is SUAVELab?:– The Small Unmanned Aerial Vehicle Laboratory, SUAVELab, is a

Multi-Disciplinary/Cross-Competency Team and specially designed laboratory facility to Design, Develop, and Deliver prototypes of beyond state-of-the-art UAV system solutions to end-user problems of critical and/or national importance.

• Additional focus areas:– Develop tools, methods, systems, and procedures for rapid, low-cost UAV

prototype design, development, and manufacture

– Provide testbed vehicles for low-cost flight testing and research

– Identify and accelerate specific promising technologies for use in UAV applications

– Identify potential research areas based on demonstrated need

• Primary Goal:– Provide a National Resource of small UAV expertise

SUAVELab IN A NUTSHELL


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Weight, lbs.

AIRWORTHINESS SIZE STRATEGY

<11 55 220

Cap

abil

ity

(R

ang

e/P

aylo

ad/E

nd

ura

nce

)

Today

Future

Pt 25:8 lb. Bird Strike to

Structure & Engine

Pt 25:4 lb. Bird Strike to

Windshield

FAI Model

AMA ModelAirplane

Ultralight (254lb.)

MiniUAV

VerySmallUAV

SmallUAV

“IRRELEVANT

ZONE”


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• Originally:– Develop a Design Guide to follow to ensure an airworthy UAV:

• “If you follow these rules, you will have a good UAV”

• Include techniques for sizing, analysis, EMI avoidance, etc.

– Drawbacks:• Began to become more like college textbook

• Some techniques are mission specific

• Preferred Approach:– Develop a minimum set of rules that are likely to prevent

development of a non-airworthy UAV:• “If you don’t follow these rules, you will likely have a bad UAV”

• Include the minimum number of rules, pre-flight tests, etc. required for an “acceptable” risk level

• Sets up “defaults” but doesn’t overrule more stringent or design specific requirements

DESIGN GUIDELINES FOR AIRWORTHINESS GUIDING PHILOSOPHY


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ASTM Draft Light SportMini-UAV Very Small UAV Small UAV Mini-UAV Aircraft

Design Criteria Element 0-11lb. 11-55lb. 55-220lb. < 55lb. < 1320lb.

Stall SpeedVariable but < 30fps 30kts 40kts NR 45kts

Landing Sink Speed 5fps 7fps 10fps NR 10fpsG-loading min +3/-1 min +4/-1 min +4/-1 Max +3/-1 Max +4/-2

Tail Volume coefficient NR

Cvt>=0.02, Cht>=0.4 for conventional configurations

Cvt>=0.02, Cht>=0.4 for conventional configurations NR By Analysis

Flutter NRTest or Best Practice AEER45 or test

Test/Analyze to set operating limit

AEER45 or test

Gust Load NR +/-20fps +/-25fpsMust be identified, if any

+/-50 fps @ Vc, +/-25fps @ Vd

Roll Rate/Time Reqm't NR NR <3s +/-30degLimit of 60deg. Bank <4s +/-30deg

Factor of Safety 1 1.251.25 (higher for certain parts) 1.5

1.5 (higher for certain parts)

Vmax in level flight <75kts <150kts<200kts, Vne < 250kts. NR 120kts

SAMPLE FROM GUIDELINE & COMPARISON


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EXAMPLE PRE-FLIGHT TESTING

• LOAD TESTING (NEW DESIGN)– Loaded to design load factor (3g or 4g) + FOS (1 or 1.25)– Control surfaces checked for binding under load

• DROP TESTS– Simulates 5-10 fps sink rate depending on size

– Wheels/tires matched to terrain (larger wheels for grass ops)

• GLIDE TESTS:


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NASA LANGLEYNASA LANGLEYASRBASRB


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• PERFORMS AIRWORTHINESS AND SAFETY REVIEWS FOR ALL LANGLEY CONDUCTED MANNED AND UNMANNED RESEARCH PROGRAMS WITHIN THE ATMOSPHERE– Composed of Aviation Safety professionals and Subject Matter

Experts, meets regularly and as needed

• PROVIDES:– Airworthiness reviews and inspections of aircraft & systems– Issues Flight Safety Releases– Hazards Analyses and Risk Assessments– Approves Flight Test Operations and Safety Reports

• REPORTS ACTIVITIES TO:– Langley Executive Safety Council– NASA InterCenter Aircraft Operations Panel– Aerospace Safety Advisory Panel

AIRWORTHINESS AND SAFETY REVIEW BOARD


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FTOSRFTOSR


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• FLIGHT TEST OPERATIONS AND SAFETY REPORT (FTSOR):– Composed of a description of the flight tests/research to be

performed, location, the systems being used, procedures, hazards, and risks

• PROVIDES:– Method for ensuring that the system is safe to operate under the

conditions desired– Hazards and Risks Assessment for the specific mission(s), and location

– Lists specific procedures to be followed

• IS REVIEWED AND APPROVED BY ASRB

FTOSR DESCRIPTION


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HAZARDS AND RISK ANALYSISHazard Analysis Summary.

Item #Phase of Operation Description of Hazard

Aircraft or Personnel

Hazard Severity

Probability of Occurrence

Risk Assessment

Code Notes

1 M, G, ILithium-based battery deep discharge, imbalance, or long term storage causes short and/or fire A III remote 3

Deep discharge and/or imbalance does not itself cause short or fire unless charging occurs when condition is undetected

2 M, G Lithium-based battery charging causes short and/or fire A III occasional 3Cell balancer is used with charger and approved charging procedures

3 M, G Fuel spill contaminates immediate area A IV occasional 34 M, G Fire occurs during fueling operation A, P III remote 3 Fueling limited until after engine has cooled5 M, G Damage to vehicle A IV occasional 3 Improper Handling

6 M, G Propeller causes injures to personnel P III improbable 3Procedures limit exposure and protective equipment required

7 T Propeller injures personnel during launch P III improbable 3Procedures limit exposure and protective equipment required

8 T Mechanical or system failure during takeoff A III occasional 3 Injury to personnel highly unlikely, mission is aborted

9 L Mechanical or system failure during landing A III occasional 3 Injury to personnel highly unlikely, mission is aborted

10 L Hard landing A III occasional 3Design criteria provides sink rate and drop test to limit damage

11 I Failure of radio control link A III occasional 3Failsafe and/or lost-link nav system features limit fly-away

12 I Failure of command/control link A III remote 3 Autonav system has lost-link feature to limit flyaway

13 I Failure of autonavigation unit A III occasional 3Vehicles equipped with UAV safety switch allow manual radio control in the event of autonav failure

14 I Failure/discharge of control system battery A III occasional 3

Procedures call for voltage level check prior to takeoff, electric airframes typically have voltage cutoff to main engine to maintain voltage to controls

15 I Fuel and/or primary battery runs out during flight A III occasional 3

Procedures require voltage or fuel check prior to takeoff. Throttle off landings practiced during pilot proficiency and airworthiness flights

16 I Mechanical or structural failure occurs during flight A III occasional 3Most control surfaces have redundant actuators, inspections during pre-flight checklist limit likelihood

17 I Avionics or System failure in-flight A III occasional 3Most control surfaces have redundant actuators, pre-flight checklist limits likelihood

18 T, L Collision of vehicle with other vehicles, aircraft or personnel A, P III occasional 3

Small scale and low speed limit possible injury, procedures limit likelihood of personnel in vicinity of vehicle during operations

19 I Collision of vehicle with other air traffic A, P II improbable 3

Small scale and low speed limit possible damage/injury, multiple procedures limit likelihood of UAS operation in close proximity to manned aircraft

20 T, L Foreign object damage A IV occasional 3Pre-flight procedure to visually inspect runway, damage limited due to low speed

21 I Birdstrike A III remote 3Noise made by UAS and flight operations usually causes birds to leave aircraft operating area


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DoD Unmanned DoD Unmanned Systems GuidelinesSystems Guidelines


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DoD UNMANNED SYSTEMS SAFETY GUIDE

• DoD Unmanned Systems Safety Guide for DoD Acquisition– Issued by USD, AT&L after collaborative effort across DoD, NASA,

and industry– Can be found at

http://www.acq.osd.mil/atptf/pdf/Unmanned_Guide_DOD_Acq_2007.pdf

• PROVIDES:– Basic safety “precepts” for both design and operations– Information on DoD “best practices” for unmanned systems (including

UAS)


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CONCLUDING REMARKS

• OPPORTUNITIES EXIST TO:

– Draw from existing knowledge– Minimize the burden on potential small UAS users– Maximize the safe utilization of the airpspace


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QUESTIONS?

LANGLEY RESEARCH CENTER - SUAVELab TEAM June 26, 2008 Michael J. Logan, P.E. Head, Small Unmanned...

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