Qualification of the Guided Parafoil Air Delivery System ...faculty.nps.edu/oayakime/ADSC/PATCAD -...

Copyright© 1997, American Institute of Aeronautics and Astronautics, Inc.

A97-31298 AIAA-97-1493

QUALIFICATION OF THE GUIDED PARAFOILAIR DELIVERY SYSTEM - LIGHT (GPADS-Light)

Sanjay Patel*U.S. Army Soldier Systems Command,

Natick Research, Development andEngineering Center, Natick, MA

Nick R. Hackettf

SSE IncorporatedPennsauken, NJ

Dean S. Jorgensen*Pioneer Aerospace Corporation

South Windsor* CT

ABSTRACT

The Guided Parafoil Air Delivery System - Light(GPADS-Light) is a fully autonomous parafoilguidance system utilizing the military GlobalPositioning System (GPS) and a high performance750 ft2 parafoil for precise delivery of payloads to apredetermined target. GPADS-Light is the firstAdvanced Precision Air Delivery System (APADS) tobe fielded to the U.S. Department of Defense. Thesesystems were purchased by the U.S. Soldier SystemsCommand, Natick Research, Development andEngineering Center (Natick) from SSE Incorporated aspart of the Warfighting Rapid Acquisition Program.This paper presents the results of the recent formalqualification by Natick of GPADS-Light, and describesPioneer Aerospace Corporation's GS-7SO parafoil,which employs a high-performance NASA LS(1)-0417airfoil.

This parafoil generates total system glide ratios inexcess of 4:1 in straight flight with 'real' payloads,providing total mission offsetialtitude ratios of 3:1.GPADS-Light has a qualified delivery accuracy of100 m circular error probable (CEP). GPADS-Light,and its commercial GPS equivalent, ORION™, havelogged over 500 flights. The military system isqualified to deliver payloads in the range 700 tol,1001b, and has further demonstrated the ability tosuccessfully deliver payloads up to 1,500 Ib.

* Project Officer, Member AIAA•f Director of Programs, Member AIAAj Program Manager, Associate Fellow AIAA

Copyright © by the American Institute of Aeronauticsand Astronautics. All rights reserved.

GPADS OVERVIEW

The Guided Parafoil Air Delivery System (GPADS) isthe Natick's designation for a precision guided deliverysystem consisting of an autonomous Airborne GuidanceUnit (AGU) and a family of high-glide ram-airparafoils. The AGU includes the Flight ManagementSystem (FMS). An on-board computer processes datareceived from a military GPS receiver as well as othersensors, and inputs the merged data to a guidancealgorithm that generates commands to control theparafoil. The FMS flies the parafoil system to a soft,upwind landing at a pre-selected site.

GPADS-Light is the smallest of the three weight classesof GPADS. GPADS-Medium and GPADS-Heavy havebeen designed by Pioneer and SSE to deliver payloadsover the range of 7,000 to 40,000 Ib, on parafoils withwing areas of 3,600 to 7,350 ft2. Payload weightsranging from 7,200 to 36,750 Ib have been successfullydemonstrated over the last three years. GPADS-Heavyis currently being adapted by NASA as the recoverysystem for the International Space Station X-38Experimental Crew Return Vehicle.

GPADS-LIGHT RAPID ACQUISITION

The U.S. Army Battle Labs have long been majorproponents of the Advanced Precision AirborneDelivery Systems (APADS) concept. GPADS-Light isthe first of these systems to be fielded to the U.S.Department of Defense (DoD). Natick's Mission NeedStatement calls for GPADS-Light to rapidly and safelydeliver warfighting essentials to support forced entry inorder to sustain operations in non-permissiveenvironments. GPADS-Light supports the need to

234American Institute of Aeronautics and Astronautics


precisely deliver critical items to combat forces on timeand to multiple targets simultaneously, while avoidingthe need for the delivery aircraft to approach the target.The system has been qualified to carry loads of 700 to1,100 Ib of usable payload from altitudes up to25,000 ft above mean sea level (MSL) and from offsetdistances in excess of 20 km (12.4 mi) with an accuracyof 100 m (328 ft) CEP.

GPADS-Light Applications

Natick and the U.S. Army Battle Labs expectGPADS-Light to fill a major role in precision airdrop,with missions including troop resupply, delivery ofsupport bundles alongside airborne troops, cachet pre-positioning, weapons delivery (single weapons,palletized systems and dispensers), delivery ofhumanitarian relief supplies, and leafleting. Theprimary users of GPADS-Light consist of small,five-to-ten-man expeditionary units of Special Forces orMarines. GPADS-Light suits their operational needsfrom a number of strategic and tactical standpoints:reduced aircraft vulnerability due to standoff delivery,the ability to target multiple drop zone (DZ) deliverypoints from a single release point, smaller DZrequirements due to precision guidance capability,reduced load dispersion and reduced DZ assembly time,just-in-time resupply of rapidly moving combat forces,day/night operational capability, and extremely lowRADAR signature.

U.S. Army Acquisition Strategy

The GPADS-Light program is one of only twoWarfighting Rapid Acquisition Programs (WRAPs)within the Department of the Army. WRAPs employall the current DoD acquisition reforms in an effort tofield new technology in under two years, instead of thefour or more years that is typical of conventionalacquisitions. Natick conducted a market survey todetermine the level of APADS technology availablefrom industry. Natick awarded a GPADS-Liglitcontract on the basis of product viability and best valueto the government. SSE had already developed theORION Precision Guided Delivery System and hadsold this commercially available system to theAustralian government. Natick's market survey

concluded that the ORION system, when integratedwith the Precision Lightweight GPS Receiver (PLGR),would meet its mission needs. In October 1995, acontract for a WRAP was awarded to SSE for 10GPADS-Light systems with options for an additional95 systems.

SYSTEM DESCRIPTION

GPADS-Light is comprised of an AGU, missionplanning and simulation software, parachute system,payload, and associated payload rigging.

Figure 1 GPADS-Light System in flight

As shown in Figure 1, the four parafoil risers areattached to the top corners of the AGU and the payloadis suspended from the AGU using a swivel harnessassembly. This canopy/AGU/payload rigging schemewas developed by SSE to allow the system to interfacewith existing Army and Air Force payload hardware.The GPADS-Medium and -Heavy parafoils, on theother hand, are rigged directly to the payload with theAGU mounted on the aft deck of the coupled payloadpallet. The GPADS-Light load is typically rigged as astack, as shown in Figure 2, with the drogue parachute



positioned atop or aside the main parafoil pack whichsits on the AGU.

Figure 2 Fully Rigged GPADS-Light and Payload

The parafoil pack and AGU are tied down to the top ofthe payload. GPADS-Light is typically static linedeployed as a ramp bundle. The system is compatiblewith a wide range of fixed and rotary wing aircraft andhas been dropped by the military from CH-46, CH-47,CH-53, UH-1, and C-130 aircraft.

AGU and Mission Planner

A detailed description of the design of the originalORION AGU and the Mission Planner has previouslybeen published by Alien1. The only practical differencebetween an ORION and GPADS-Light AGU is thatGPADS-Light utilizes the military, P-code GPS system,whereas ORION was developed using commercialGPS. Other than a few enhancements, functionality isthe same for both systems.

Mission Planner

The GPADS-Light Mission Planner allows the user tosetup and simulate missions in order to produce a final,'rugged' mission plan. Given target, payload, andpredicted wind conditions, the Mission Planner willprovide an optimum release point for maximumstandoff at a user-defined release altitude (Figure 3).

Figure 3 Mission Planner Main Input Screen

The simulator allows the user to investigate the effectsof changing wind conditions and release point error onthe success of the mission (Figure 4).

Figure 4 Simulation Result Screen

In this way, the user can determine a release point thatwill provide GPADS-Light with the maximumprobability of mission success, given worst caseconditions and restrictions.



Airborne Guidance Unit

The basic components of the GPADS-Light AGU are asfollows:

80286 single board computer80287 math co-processorPLGR military GPS receiverBarometric pressure sensorFluxgate compassServo actuators

The AGU computer components and flight controlsoftware comprise the Flight Management System(FMS). The AGU components are mounted in awaterproof, glass reinforced resin housing.

When powered up by removal of the "Hot Launch" pin,the FMS automatically conducts built-in-test (BIT), andsignals a pass or fail condition by means of an LED.BIT includes verification that the PLGR has the correct'key' and 'almanac' information to facilitate operationas a P-code (military) receiver.

After BIT, the FMS enters GPS acquisition mode. If thedelivery aircraft is equipped with a GPS repeater, thenthe AGU will be able to be fully locked on prior todeployment. Anytime prior to deployment that theAGU is tracking GPS, the AGU indicates by LEDwhether the system is currently in or out of range of thetarget. When a GPS repeater is not present, the AGU isonly able to acquire satellites after deployment from theaircraft.

When deployed from the aircraft, extraction of adeployment pin from the AGU by the main canopy bagsignals the FMS to switch to tactical mode. The AGUcontrols the flight of the parafoil in the conventionalmanner, using the servo actuators to produce a mixtureof differential and simultaneous deflection of the leftand right trailing edges.

A GPS repeater was not used throughout the testing forqualification of GPADS-Light. Typical times to GPStracking following deployment ranged from 30 to 250seconds. During times when GPS tracking is not

available, the AGU will 'dead reckon' the navigation ofthe mission based on compass and barometric pressuresensor data alone. The system assumes that the releasepoint was correct, and that the wind profile is the sameas that programmed into the AGU as part of the missionplan.

Once GPS tracking is established, the FMS accuratelynavigates the system through any programmedwaypoints to the programmed target area, whiledetermining and compensating for actual windconditions hi real-time. Upon reaching the target area,GPADS-Light maneuvers to lose excess altitude beforethe FMS controls the system through a final approachand soft, into-wind landing at the target coordinates.

Parachute System

The parachute system consists of a 13.13-ft nominaldiameter radial cruciform drogue parachute and a750 ft2, 23-cell parafoil. The drogue pack is static-linerigged to the delivery aircraft (Figure 5).

Figure 5 Deployment Sequence

The drogue riser assembly performs several deploymentfunctions. First, as the load separates from the aircraft,a cut-knife attached by lanyard to the drogue riser cutsthe webbing which holds the parafoil/AGU assemblydown to the payload. This allows the swivel harnessassembly, which attaches the payload to the AGU, toextend during drogue parachute deployment, rather thanmain canopy deployment. In this way, the peak snatchload on the system at swivel harness full-stretch isminimized. The drogue is then extracted and inflates.



The drogue riser attaches to a cut loop which ties theparafoil pack to the AGU. The cut loop is severed by atime-delay pyrotechnic cutter which is armed onrelease. Load is then transferred from the tie-downassembly to the parafoil deployment bag. The droguethen extracts the parafoil.

As the parafoil is stripped from its deployment bag,time-delay reefing cutters are armed. Once the parafoilcanopy clears the bag, the bag and drogue riser aredrawn over a drogue canopy pull-down line attached toa bridle on the upper surface of the parafoil and runningthrough a channel in the drogue riser. The deploymentbag, drogue riser and inverted drogue then remainattached to the system for the entire flight.

The parafoil is deployed in four stages, employingPioneer's patented spanwise de-reefing technique2

(Figure 6). In the first stage, the outermost cells of thecanopy inflate while most of the parafoil's cells areclosed by a series of lacing loops affixed to two of theparafoil keels. At a preset time, a cutter severs alocking knot, allowing the second stage of cells todeploy and inflate, revealing a smaller number of centercells still closed off.

Figure 6 Patented Parafoil De-Reefing Sequence

Finally, a second cutter functions, allowing the centercells to deploy and inflate. A short time later, the FMScommands both control lines to retract, releasing pre-settrailing edge brakes. The parafoil is now fully inflatedand flying.

The GS-750 flies operationally at wing loadingsranging from 1.16 to 2.23 lb/ft2. At these wingloadings, GPADS-Light has a wind penetration of 22 to30 knots.

Payload

The primary Army payload for GPADS-Light is astandard Container Delivery System (CDS) bundle.The CDS bundle is a 4 ft x 4 ft container incorporatinga skidboard for interface to the aircraft, crushablehoneycomb for impact attenuation, and an A-22 cargosling for cargo containment and load suspension.

GS-750 Parafoil

The GPADS-Light main parachute is a 750 ft2 parafoildesignated the GS-750 by Pioneer. The GS-750 isunlike any other cargo parafoil in that it takesadvantage of a thick supercritical airfoil section toachieve superior lift-to-drag performance. Theoreticaland empirical studies by McGhee and Beasley3 in theearly 1970's showed that the subcritical characteristicsof supercritical airfoil sections indicated performanceincreases over conventional airfoil sections. With aninterest hi developing high-performance wings forpropeller-driven aircraft, they designed an airfoil shapewhich was 17 percent thick and had a blunt nose and acusped lower surface. This airfoil, which theydesignated the GA(W)-1 for General Aviation(Whitcomb), had several key features including a largeupper surface leading edge radius to attenuate peaknegative pressure coefficients and delay stall onset athigh angle-of-attack, and a contoured profile to provideapproximate uniform chordwise load distribution.

The investigators' work continued throughout the '70's,and resulted in a family of low- and medium-speedairfoils based on the GA(W)-14. In the process, theymodified the 17-percent low-speed airfoil to reduce thepitching moment coefficient. This section is shown inFigure 7. By the end of the '70's the now-designatedLS(1)-0417 airfoil was in use with the Beech Model 77and Piper PA-38 Tomahawk aircraft.



Figure 7 LS(1) and Clark-Y AirfoilsIn 1990, Pioneer undertook the investigation of aparafoil constructed with the NASA LS(1)-0417 airfoil.("LS(1>" indicates "low speed (first series)" while"0417" indicates an airfoil with a thickness of 17percent chord and a design lift coefficient of 0.4.) Aspart of the Advanced Recovery Systems for AdvancedLaunch Vehicles program (NASA contract NAS8-36631, Phase 2), Pioneer tested two 1,200 ft2 parafoilsin the NASA Ames Research Center 80 ft x 120 ft testsection of the National Full-scale AerodynamicComplex5. The two models were identical in everyrespect except the airfoil. One model had a 17-percentthickness Clark-Y section and the other had the NASALS(1)-0417 section (Figure 7). Both models had anaspect ratio of 3.0:1 and were constructed of zero-porosity coated Nylon. The two models were riggedwith quadrifurcated Kevlar suspension lines. The ratioof line length to span was 1.0:1 for both models.

The LS(1) model is shown flying in the wind tunnel hiFigure 8. Six components of force were measured.Load cells were used to measure chordwise andspanwise loading as well as lateral forces.

Results of these tests indicated that at low-liftconditions, the LS(1) wing had approximately 7%higher lift-to-drag (L/D) than the Clark-Y wing.Maximum lift for the LS(1) was reduced, however,owing to the lack of forward camber. Still, results wereencouraging and NASA Ames Research Center andNatick pursued experimental and theoretical evaluationof an LS(1) wing with a much reduced inlet.

NASA Ames and Natick tested a 45%-scale version ofthe Pioneer wing, also in the NASA Ames 80 ft x 120 ftwind tunnel6. Results of these tests show that a wingwith a 4% inlet produces a 25% increase in maximumL/D over the 8.4%-inlet LS(1) wing tested by Pioneer.NASA Ames/Natick results for the LS(1) wing areshown alongside Pioneer's Clark-Y data in Figure 9.The LS(1) canopy maximum L/D of 5.1:1 is 16%higher than the maximum L/D of the Clark-Y. Basedon these results, Pioneer set out to develop a functionalLS(1) parafoil.

0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80

CL

Figure 9 L/D Performance of LS(1) vs Clarke-Y

Figure 8 Wind Tunnel Testing of LS(1) Parafoil



In setting design details, including aspect ratio, inletdesign, rigging angle, number of cells, materials, cross-port venting, line length ratio, number of reefing stages,deployment brake setting and deployment stagingtimeline, Pioneer employed the standard designpractices as ultimately published by Lingard7 in 1995.In fact, features of the GS-750 were specificallyincluded in the case study presented by Lingard in thesection of the referenced design monograph entitled"Detail Design."

The final, qualified GPADS-Light parafoil is a 23-cellLS(1)-0417 canopy with a zero-porosity Nylon uppersurface and low porosity (0-5 ftVtf/min @ Vi" waterhead) lower surface. The canopy has an aspect ratio of3.0:1. Suspension lines are constructed of Spectra™and have a line length-to-span ratio of 1.0:1.

Considerable attention was paid to other design details,notably tip droop and rigging angle. Proper tip droop isessential to ensure adequate inflation and controlcharacteristics, especially given the lateral stabilitycharacteristics of this supercritical airfoil.

SYSTEM PERFORMANCE

The first ORION Precision Guided Delivery System,flown hi 1992, utilized a 375 ft2 parafoil (modifiedforerunner of the MC-4 personnel canopy which iscurrently in use by the U.S. Army). In 1993, SSEtransitioncd to flight tests utilizing Pioneer's prototypeGS-750 LS(1) parafoil to investigate the benefits of thehigh performance wing.

In the spring and summer of 1994, a U.S. ArmyBattlelab conducted a series of Battlelab WarfightingExperiments (BWEs) at Fort Bragg, NC, to determinethe viability of ORION for the GPADS-Light mission.These tests allowed the government to providefeedback to SSE and Pioneer, resulting in productimprovements based on user input.

The government was also able to test the ORIONsystem in a more operationally representative scenario,providing the developers with useful experience. Thecontractor-funded development, along with thegovernment funded evaluation of the commercially

available ORION system, led to the 1995 award of theWRAP to SSE for the procurement of the first ten of upto 105 GPADS-Light systems.

Pre-qualification

In September 1996, Natick conducted a series of tenpre-qualification flight tests. The tests were designed tovalidate the performance of the PLGR in theGPADS-Light application, and to confirm thedeployment and flight characteristics of the upgradedGS-750 parafoil system. Minor modifications had beenmade to the parafoil brake release configuration sincedelivery of ORION systems to the Australian Army inOctober 1995.

Tests were conducted at the U.S. Army Yuma ProvingGrounds (YPG), AZ. GPADS-Lights, rigged tostandard CDS bundles weighing between 700 and1,100 Ib, were delivered singly from a C-130 Herculesflying at 130 KIAS at altitudes of 10,000 to 18,000 ftMSL from standoffs of 4 to 6 km. The tests confirmedthe validity of the current design configuration anddemonstrated a system accuracy of 90 m CEP. Sevenof the ten units landed within 100 m of the target, whilethree of the units landed within 30 m (Table I).

Tests 1A through 5A were conducted in conditionswhere the actual winds were significantly differentfrom the winds planned into the missions earlier in theday. Air space and safety-footprint considerationsresulted in the release point being moved. The missdistances on Tests 2A and 5A were ascribed to the longlock-on times of the GPS receiver (253 and162 seconds respectively) resulting in the systems deadreckoning from an assumed, but then obsolete releasepoint. The extended lock-on times in both cases causedthe systems to be unable to reach the target even afterestablishing full GPS guidance. The systems in Tests1A, 3 A, and 4A achieved GPS tracking fast enough toallow the systems to compensate sufficiently for thechanged winds and release point.

The miss in Test 9A was attributed to an error in therigging of the right winch control line which caused asevere built in right-hand turn for which the systemcould not fully compensate.



Technical Type Qualification

On the basis of pre-qualification test results, Natickelected to count these tests as part of the formal systemevaluation, and to proceed directly to technical typequalification testing of GPADS-Light. Technical typequalification testing is the first of two steps leading toGPADS-Light Type Classification and issuance of aNational Stock Number. The second step in the processis operator qualification in which the representative"user groups" demonstrate the ability to properlyprogram, rig, deploy and maintain the system in anoperationally representative setting, using realpayloads.

Technical type qualification testing was conducted atYPG over a four-day period in October 1996. The U.S.Army conducted 28 tests in four separate missions.Payload weights ranged from 700 to 1,495 Ib. Again,units were deployed from a C-130 Hercules flying at130 KIAS. Release altitudes ranged from 18,000 to25,000 ft MSL at standoffs from 7 to 21 km. Unitswere either deployed separately, or two at a time on aten-second spacing.

Due to weather and air-space limitations, many of thereleases were forced to be downwind and crosswindfrom the target. These tests clearly demonstrated thebenefits of GPADS-Light over conventional, roundparachute air delivery systems, showing that the user isnot limited by the restriction of only releasing directlyupwind of the intended target.

The results of these tests are summarized in Table I.Combined with the ten pre-qualification tests, 17 of 38units landed within 100 m. Fifty percent of the unitslanded within 103 m. Skewing the results were fourtests which flew improperly.

Analysis after Test 4 revealed a problem with thatAGU's internal CPU clock. This caused an incorrectinitialization of the GPS receiver, and thus preventedthe PLGR from acquiring a fix. The system deadreckoned for the entire duration of the flight. The clockwas reset, and appeared to then function correctly.Following a repeat of the problem with the same AGUon Test 16, it was confirmed that the clock failed to

function reliably. The CPU was replaced, and thesystem was used on subsequent flights with noproblems.

Two other units, Test 11 and Test 22, were viewed tospiral to the ground immediately after apparently goodparafoil deployments. Close examination of the canopybrake release mechanism revealed an isolated problem.

A vinyl-coated steel cable affixed at one end to theparafoil aft riser assembly is used to secure the foldedriser and set the brakes. During canopy rigging, thiscable is inserted through an eyelet in the parafoilcontrol winch line. On AGU-commanded brakerelease, the left and right control which lines are hauledin simultaneously. Ordinarily, the winch lines pull thebrake release cables out from their respective Nylon setloops, thereby releasing the brakes.

However, in tests 11 and 12, the highly loaded Nylonloop pinched the vinyl coating on the steel cable to suchan extent that the cable could not be extracted by thewinch line. Only one side of the canopy brakes wasreleased, causing the parafoil to fly in a permanent tightspiral. Following technical type qualification testing,the flexible plastic-coated brake cable was replacedwith a solid stainless steel pin. This designmodification was subsequently demonstrated inoperational flight tests with the U.S. Marine Corps.Partial brake release has never been observed since theintroduction of this new brake release pin.

Based on these findings, at the time of the writing ofthis paper, the Army's Type Qualification ReviewBoard is considering the exclusion of these fouranomalous tests from the data base for the purpose ofevaluating GPADS Light performance. Meanwhile, inNovember 1996, Natick publicly released the followingqualification test results: "GPADS-Light hassatisfactorily demonstrated the ability to deliverpayloads weighing from 700 to 1,100 Ib at releasealtitudes ranging from 10,000 to 25,000 ft MSL atoffsets up to 21 km. GPADS-Light lands within 260 mof the target 94% of the time, within 150 m 71% of thetime, within 100 m 50 % of the time, and within 55 m21 % of the time."



GPADS-Light System Accuracy

Of the 38 drop tests conducted during technicalqualification of GPADS-L, six were affected bycircumstances, as described above, that were beyondthe control of the FMS. The remaining 32 tests wereconsidered to be those that represent the capableaccuracy performance of GPADS-Light (Figure 10).

Figure 10 Accuracy Results of GPADS-Light

These results demonstrate the inherent accuracyperformance of the GPADS-Light system. Thedistribution of these data is as shown in Table II.

Distance from Target50m100m200m250m

Percent of Systems19%50%88%98%

Table II Landing Accuracy Distribution

OPERATOR QUALIFICATION

In December 1996, GPADS-Light contractorsconducted a one-week formal rigging and missionplanning training course for personnel from all fourservice branches. In January 1997, the U.S. ArmyOperational Test and Evaluation Command (OPTEC)commenced an independent series of operationally

representative trials designed to demonstrate the abilityof military personnel to adequately plan a mission,program the AGU, rig and deploy the unit, and recover,maintain and recycle the system. As of the end ofJanuary 1997, OPTEC had successfully conducted thefirst five trials. Natick anticipates completion ofOperator Qualification testing in March or April 1997.Successful completion of operator qualification willlead to Type Classification of GPADS-Light.

ADDITIONAL ACTIVITIES

In addition to formal qualification testing,GPADS-Light has been undergoing extensiveevaluation by the U.S. Marine Corps 7th LandingSupport Battalion. From October 1996 throughFebruary 1997, the Marines conducted over 30 tests ofGPADS-Light. In March, they used GPADS-Light toresupply forward troops during the Hunter WarriorAdvanced Warfighting Exercises at the Marine CorpsAir Ground Combat Center, Twenty-Nine Palms, CA.The Marines have deployed GPADS-Light from avariety of aircraft including C-130, UH-1 Huey, CH-46BullPhrog, CH-47 Chinook, and CH-53 Super Stallion.

FUTURE DIRECTION

Natick and the GPADS-Light developers are evaluatingexpansion of the performance envelope as well asreduction in logistics burden. Activities includeevaluation of the flight characteristics of a permanentlyreefed parafoil for lighter payloads, demonstration offlight characteristics at higher wing loading, anddevelopment of mechanical disreefing devices.Meanwhile, the government continues to pursue othersystem applications, including embassy compoundresupply, aircraft decoys, marine mine emplacement,rocket thrust section recovery, sensor and munitionsdelivery, and leaflet delivery systems.

REFERENCES

1. Alien, Roger, F., "ORION™ Advanced PrecisionAirborne Delivery System," AIAA-95-1539-CP,13th AIAA Aerodynamic Decelerator SystemsTechnology Conference, Clearwater Beach, FL.,May 1995.



2. Reuter, James D., "Gliding Wing ParachuteApparatus with Staged Reefing DeploymentMeans," United States Patent No. 4,846,423, 11 Jul1989.

3. McGhee, Robert J., and Beasley, William D.,"Low-Speed Aerodynamic Characteristics of a 17-Percent-Thick Airfoil Section Designed forGeneral Aviation Applications," TN D-7428,NASA Langley Research Center, Hampton, VA,Dec 1973.

4. McGhee, Robert J., Beasley, William D., andWhitcomb, Richard T., "NASA Low- andMedium-Speed Airfoil Development," TM 78709,NASA Langley Research Center, Hampton, VA,1973.

5. Geiger, Robert H., and Golden, Ronald A.,"Advanced Recovery Systems Wind Tunnel TestReport - Series 2," ARS-WT-2, Pioneer AerospaceCorporation, South Windsor, CT, Aug 1990.

6. Ross, James C., "Computational Aerodynamics inthe Design and Analysis of Ram-Air-InflatedWings," AIAA-93-1228-CP, RAeS/AIAA 12th

Aerodynamic Decelerator Systems TechnologyConference, London, England, May 1993.

7. Lingard, J. Stephen, Ram-Air Parachute Design.Seminar Series 95-01, AIAA AerodynamicDecelerator Systems Technical Committee, Reston,VA, 1996.

Test1A2A3A4A5A6A7A8A9A

10A123456789

10111213141516171819202122232425262728

Dot*9/4/969/4/969/4/969/4/969/4/969/6/969/6/969/6/969/6/969/6/96

10/7/9610/7/9610/7/9610/7/9610/7/9610/7/9610/7/9610/7/9610/7/9610/7/9610/8/9610/8/9610/8/9610/8/9610/8/9610/8/9610/8/9610/8/9610/8/9610/8/96

10/10/9710/10/9710/10/9710/10/9710/10/9710/10/9710/10/9710/10/97

PayloadWeight (Ib)

1,1001,1001,100

700700

1,0871,0911,075

n/a1,0551,0871,0911,0751,0551,0601,0551,0661,0601,0971,0761,0701,0851,0681,0801,0811,0551,1001,0701,4921,4951,1101,0801,1201,1101,1001,1201,1501,100

Release ConditionsAltitude(ft MSL)

10,00010,00010,00010,00010,00018,00018,00018,00018,00018,00018,00018,00018,00018,00025,00025,00025,00025,00025,00025,00018,00018,00018,00018,00018,00018,00018,00018,00018,00018,00025,00025,00025,00025,00025,00025,00025,00025,000

Offset(km)

44444666668888

1111111111117777777777

2121212121212121

Range(deg)

290290290290290170170170170170290290290290290290290290290290210210210210210210210210210210210210210210210210210210

Velocity(KIAS)

130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130130

Mean WindMagnitude

(kt)1515151515141414141412121212121212121212121212121212121212121212121212121212

Bearing(deg)

270270270270270808080808080808080808080808080

110110110110110110110110110110130130130130130130130130

TargetElevation(ft MSL)

400400400400400400400400400400

1,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,0901,090

AccuracyDistance

(m)90

58090

100180209030

80020308535

3,0002855

250180260100

5,000190140115108

10,000959597

250235

20,000100110103110102107

Bearing(deg)

18030030031031033017016025016013530

18034085

1201402251351302002503090

13545

13080

18019034021033513060

33030550

Comment

250 s delay in GPS lock-on

Rigging error

No GPS lock-on

Incomplete brake release

No GPS lock-on

Incomplete brake release

Table I GPADS-Light Qualification Test Results


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