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Design of UAV Systems. c 2002 LM Corporation. Sorties rates. Lesson objective - to discuss Sortie rate analysis including … - Mission planning and preparation - Aircraft preparation and maintenance - Preflight / execution / debrief - Crew considerations.

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  1. Design of UAV Systems c 2002 LM Corporation Sorties rates • Lesson objective - to discuss • Sortie rate analysis • including … • - Mission planning and preparation • - Aircraft preparation and maintenance • - Preflight / execution / debrief • - Crew considerations Expectations - You will understand the basic elements of a sortie and be able to make sortie rate estimates 7-1

  2. Design of UAV Systems c 2002 LM Corporation Sorties rates Definitions • Sortie (Webster’s New Collegiate Dictionary) • – One mission by a single aircraft • Sortie rate (The RAND Corporation*) • – The number of missions one aircraft can fly in one day including time in the air and on the ground or • SR = 24hours/[FT + GT] • where • FT = flight time  2target distance/block speed • GT = ground time = TAT + MT • and • TAT = turn around time  3 hours • MT = maintenance time * http://www.rand.org/publications/MR/MR1028/ 7-2

  3. Design of UAV Systems c 2002 LM Corporation Sorties rates Sortie elements • Mission planning and preparation time • Military - time required to plan and communicate an overall air operation and translate it into individual aircraft flight plans that everybody understands • - Typically planned for days or weeks and conducted daily • Civilian - time required to prepare and file a flight plan and receive a clearance • - Manned aircraft can plan a simple flight and get an IFR clearance in a minimum of an hour • - VFR flight preparations could be done in minutes • - Unmanned aircraft may have to negotiate approvals far in advance (varies by country and region) 7-3

  4. Design of UAV Systems c 2002 LM Corporation Sorties rates Sortie elements • Aircraft maintenance and preparation time • All aircraft require servicing (fuel, oil, etc.), loading and scheduled maintenance (oil and filter change, etc) • - Servicing can often be done during mission planning • - Loading time varies widely • - Military aircraft require special preparations to include weapons assembly and check out • - Minimum “turn time” is typically 15-30 minutes • Unscheduled maintenance also occurs and often must be done before flights can be resumed • - Flight critical items must be fixed, others can be “placarded’ and fixed later • - Many operators do phase maintenance (periodic replacement) to minimize schedule disruptions 7-4

  5. Design of UAV Systems c 2002 LM Corporation Sorties rates Sortie elements • Pre-flight, loading and system checks • All aircraft require external pre-flight ground checks • - From simple “walk-around” to thorough inspection • - Typically takes 5 to 10 minutes • All manned aircraft require loading • - Includes pilot, crew and passengers • - Time varies from 1 minute (pilot only) to 30 minutes • Non-perishable cargo can be loaded during aircraft maintenance and preparation • All aircraft require pre-start system checks • - Unmanned aircraft require the most time • - Minutes to hours • - Manned aircraft time varies from 1 to 15 minutes 7-5

  6. Design of UAV Systems • Flying the mission…. • Start/check the engine(s) - 1 to 5 minutes • Get ground clearances - seconds to minutes • Taxi to active runway - 2 to 15 minutes • Perform pre-takeoff checks - 0 to 5 minutes • Takeoff - 1 minute • Climb - Seconds to 10s of minutes • Cruise/ingress - function of mission distance & speed • Pre-penetration refuel - 15 to 30 minutes • Loiter/surveil - minutes to hours • Engage in combat - 2 to 5 minutes • Deliver cargo - minutes (drop) to hours (land) • Post-penetration refuel - 15 to 30 minutes Cruise/egress - function of mission distance & speed • Get clearances and land - 1 to 10s of minutes • Post mission checks (military aircraft) - 0 to 5 minutes • Taxi and shut down - 2 to 15 minutes or or c 2002 LM Corporation Sorties rates Sortie elements “Useful Work” 7-6

  7. Design of UAV Systems c 2002 LM Corporation Sorties rates Sortie elements • Debrief - the time required to report and/or document the results of a mission • Civilian debriefs focus on record keeping and incident and maintenance reports • - 2 to 30 minutes • Military debriefs are extensive • - Everything included in civil debriefs plus … • - Mission assessments • - Intelligence information • - Procedures • - Etc. • - Can take hours 7-7

  8. Design of UAV Systems c 2002 LM Corporation Sorties rates Crew considerations • Civilian and peacetime military ground crews typically operate 8 hours per day, 5 days per week. • Civilian air crews operate on flight hour basis • Air transport crews are typically limited to a 14 hour duty day or 10 flight hours for reasons of safety • - Duty day includes air and ground time • On deployments, military air and ground crews operate 12 hours per day, 7 days per week • - Crew:aircraft ratio usually > 1, e.g. 1.25 for fighters • UAV crews (ground and flight) operate on 8 or 12 hour duty day basis Aircraft sortie rates typically are limited by crew considerations - most aircraft can fly more hours than their crews can work - including UAVs 7-8

  9. Design of UAV Systems c 2002 LM Corporation Sorties rates Figures of merit • Civilian figures of merit (FOM) are typically expressed in terms of numbers of revenue flights per day • Military figures of merit are typically expressed in terms of numbers of sorties generated per day per aircraft (strike missions) or sorties for required coverage (surveillance missions) under 2 conditions: • Surge - what can be done in an “all-out” effort for short periods of time • Sustained - what can be done in continuous effort over long periods of time • Cost is an important part of military FOMs also 7-9

  10. Design of UAV Systems Mission Control Ground crew Mission Planning and Preparation - min 180 Intelligence update 60 Flight plan 60 Clearances 60 Aircraft Preparation and Maintenance (parallel activity) - min 180 Scheduled maintenance 120 Fuel/oil and roll out 30 Ground checks 30 Above completed in advance Preflight - min 6 6 Load mission 2 2 Mission verification 2 2 Walk around inspection and system checks 2 2 Mission execution - min 20 241 Start engine 1 1 Clearances 1 1 Taxi 5 5 End of runway/pre-take off checks 3 3 Takeoff 1 Climb 10 Cruise out 10 Loiter/surveillance 180 Cruise back 10 Hold for landing 5 Land 5 3 3 End of runway inspection and safing Taxi 5 5 Shut down 2 2 Quick turn - min 15 15 “Thru flight” inspection and refuel 15 Reports 15 Sortie requirement (hr) 0.68 4.37 c 2002 LM Corporation Sorties rates Sortie rate example Above completed in advance SR = 24/7.37 = 3.3 FT = 3.6 hrs 7-10

  11. Design of UAV Systems TAT  3 hrs c 2002 LM Corporation Sorties rates RAND data • Therefore: • SR  24hours/[1.68FT + 6.4] SR (previous example) = 1.9 * http://www.rand.org/publications/MR/MR1028/ 7-11

  12. Design of UAV Systems c 2002 LM Corporation Sorties rates Intermission 7-13

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