An Experimental Investigation of Damaged Arresting Gear Tapes for the Langley Aircraft Landing Dynamics Facility

NASA / TM-1999-209839

An Experimental Investigation of Damaged

Arresting Gear Tapes for the Langley

Aircraft Landing Dynamics Facility

Angela J. Mason Langley Research Center, Hampton, Virginia

December 1999

The NASA STI Program Office ... in Profile Since its founding, NASA has been dedicated to CONFERENCE PUBLICATION. Collected the advancement of aeronautics and space papers from scientific and technical science. The NASA Scientific and Technical conferences, symposia, seminars, or other Information (STI) Program Office plays a key meetings sponsored or co-sponsored by part in helping NASA maintain this important NASA.

role.

SPECIAL PUBLICATION. Scientific, The NASA STI Program Office is operated by technical, or historical information from Langley Research Center, the lead center for NASA programs, projects, and missions, NASA's scientific and technical information. The often concerned with subjects having NASA STI Program Office provides access to the substantial public interest.

NASA STI Database, the largest collection of aeronautical and space science STI in the world.

TECHNICAL TRANSLATION. English- The Program Office is also NASA's institutional language translations of foreign scientific mechanism for disseminating the results of its and technical material pertinent to NASA's research and development activities. These mission.

results are published by NASA in the NASA STI Report Series, which includes the following Specialized services that complement the STI report types: Program Office's diverse offerings include creating custom thesauri, building customized TECHNICAL PUBLICATION. Reports of databases, organizing and publishing research completed research or a major significant results ... even providing videos.

phase of research that present the results of NASA programs and include extensive For more information about the NASA STI data or theoretical analysis. Includes Program Office, see the following: compilations of significant scientific and technical data and information deemed to • Access the NASA STI Program Home Page be of continuing reference value. NASA at http'//www.sti.nasa.gov counterpart of peer-reviewed formal professional papers, but having less • E-mail your question via the Internet to stringent limitations on manuscript length help@sti.nasa.gov and extent of graphic presentations.

• Fax your question to the NASA STI Help TECHNICAL MEMORANDUM. Scientific Desk at (301) 621-0134 and technical findings that are preliminary or of specialized interest, e.g., quick release • Phone the NASA STI Help Desk at reports, working papers, and (301) 621-0390 bibliographies that contain minimal annotation. Does not contain extensive Write to: analysis.

NASA STI Help Desk NASA Center for AeroSpace Information CONTRACTOR REPORT. Scientific and 7121 Standard Drive technical findings by NASA-sponsored Hanover, MD 21076-1320 contractors and grantees.

NASA / TM-1999-209839

An Experimental Investigation of Damaged

Arresting Gear Tapes for the Langley

Aircraft Landing Dynamics Facility

Angela J. Mason Langley Research Center, Hampton, Virginia National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-2199

December 1999

The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufactures by the National Aeronautics and Space Administration.

Available from: NASA Center for AeroSpace Information (CASI) National Technical Information Service (NTIS) 7121 Standard Drive 5285 Port Royal Road Hanover, MD 21076-1320 Springfield, VA 22161-2171 (301) 621-0390 (703) 605-6000 ABSTRACT An experimental investigation was performed on damaged arresting gear tapes at the Langley Aircraft Landing Dynamics Facility. The arrestment system uses five pairs of tapes to bring the test carriage to a halt. The procedure used to determine when to replace the tapes consists of a close evaluation of each of the 10 tapes after each run. During this evaluation, each tape is examined thoroughly and any damage observed on the tape is recorded. If the damaged tape does not pass the inspection, the tape is replaced with a new one. For the past 13 years, the most commonly seen damage types are edge fray damage and transverse damage. Tests were conducted to determine the maximum tensile strength of a damaged arresting gear tape specimen. The data indicate that tapes exhibiting transverse damage can withstand higher loads than tapes with edge fray damage.

INTRODUCTION The objectives of this study were (a) to develop a methodology for testing aging tapes, (b) to determine the tensile load strength of damaged arresting gear tape specimens, and (c) to develop recommendations to improve the procedure for replacing damaged arresting gear tape at the Langley Aircraft Landing Dynamics Facility (ALDF). An overview of the ALDF is pictured in figure 1. This paper presents data showing the effects of transverse damage and edge fray damage on the tensile load capability of the tapes.

The arrestment system is a key component of the ALDF. This system is designed to stop a 58-ton sled traveling at speeds of 220 knots. No failures of the arrestment system have occurred to stop the test carriage, but damage has occurred to the system tapes and the test carriage. Although the incident rate is less than 0.1 percent, tape failure could result in extensive damage to the arrestment system and the carriage. Repairs to any component of the facility can be costly and time-consuming and affect the schedule of planned tests. The arrestment system makes use of five sets of steel cable pendants with a nylon tape attached to each end of the pendant for a total of 10 tapes. Although the system consist of five assemblies, three of the five are adequate to stop the test carriage in approximately 600 ft.

Figure 2 shows an arrestment of the test carriage during a typical run.

The facility uses an inspection procedure after each test run to determine the condition of each tape. This evaluation involves intense screening of the tapes to detect and report

damage. The damagedareasare further examinedto ensurethat the tapes meet the

minimum strengthrequirements beforeproceedingwith the test. When a tape fails the

inspection, it is replaced with a newtape. Several typesof damage thatcancausea tapeto

fail are notedin the Inspectionand Replacement Procedurefor the ALDF. The tests

performedfor this studywereon specimens exhibiting edgefray damageandtransverse

damage.The edgefray damagemanifestsitself as a loss in tape integrity nearthe tape

edgesas transverse weavingmaterialfails; thus loose axial fibers will fray. Then the

damaged edgesneedto be cut off, which makesthe tape more narrow (fig. 3(a)). This

damagelinearly decreases the tensile load capacityas tape width decreases.Transverse

damageoccurswhen the transverse weaveof the tape materialunravels. This damage

indicates internalfailure of the tensileweave.Transverse damage manifestsitself by worn

spotsor cutsthrough the outerweave of the tape(fig. 3(b)). When the transverse weave

unravels, thetensileloadcapacity decreases. A testwasconducted on oneof the specimens

exhibitingsimulated damage.Simulated damageinvolvedtaking a specimen in fairly good

conditionandmanuallyapplyingdamage to the specimen usingtoolsto put severalcutsand

bruises onthematerialin varioussections of the specimen.

FACILITY

The LangleyAircraft LandingDynamicsFacility is a uniquenationaltest facility at the

NASA LangleyResearch Centerandis locatedin Hampton,Virginia. This facility hasthe

ability to evaluate aircraftlandinggearsystems includingnewandadvanced concepts.Tests

canbeperformedon full-size aircraftlandinggearsystems. Thesetestscanbe conducted

underclosely controlledconditionson runway surfacesto simulatelanding and takeoff

operationsof aircraft under many different simulatedweatherconditions. Researchis

performedon phenomenasuch as hydroplaning,tire friction, tire braking, slush drag,

cornering,steering, tire performance, andrunway grooving. The accomplishments of tests

attheALDF havemadesignificantimpactsonaircraftprogress.

The mainfeaturesof the ALDF includea waterjet propulsionsystem, the testcarriage,

andthe arrestment system. The high-pressure waterjet propulsionsystempropelsthe test

carriagealongthe2800-ftrunway. The components of this systemarean L-shapedvessel

thatholds 26 000 gal of water, threeair storage tankspressurized to a maximumof 3150

psi,andahigh-speed shutter valvewhichcontrolstheflow of thewater. The test carriageis

constructed of tubular steelmembersandweighs58 tons. Locatednearthe centerof the

carriageis a 20-ft-wideand40-ft-long openbay. The openbay is part of the test section

areausedfor mountinglandinggearsystemsandothervarioustest articles. A hydraulic

systemis usedto position the drop carriage, applyloads,andobtainsink speeds up to 20

ft/sec on tires. Positionedon the front of the carriageis a noseblock that has five V-

grooves, which is usedto capture the five arresting gearcableson the arrestment system.

Reference 1 givesa moredetaileddescription of theALDF.

ARRESTMENT SYSTEM The arrestment system (fig. 4), located 1800 feet down the track, is used to bring the test carriage to a halt. A typical test can include speeds up to 220 knots. The main components of this system include five independent sets of energy absorbers, a water cooling system, a pendant support gantry tower, and 10 arresting gear tapes. Connected to each energy absorber is the cable-tape assembly in which a tape is attached to each end of the five cables.

Each cable assembly consists of a steel wire pendant that is 1.25 in. in diameter and 100 ft long. The system is capable of absorbing 167 000 000 ft-lb of energy by raising the temperature of water contained in five sets of tubs. Each energy-absorber assembly contains a tub, rotation shaft, and a spool. If any two sets of the energy absorbers fail, this system still has sufficient energy absorbing capability to arrest the carriage successfully.

The gantry tower supports the arresting gear cables, is used to elevate the cables when towing the carriage down the track, and supports the five cable assemblies to the precise nose block position for the test carriage and arrestment system engagement. (See fig. 5.)

ARRESTING GEAR TAPE The arresting gear tape is made of woven nylon and is extremely stiff. To accommodate wear and abrasion on the tape, the top and bottom edges of each tape are reinforced with extra nylon. The tape is also treated with a black resin polymer to help prevent deterioration because of weather conditions.

The test specimens used for the experiment were selected from aged arresting gear tapes that had been replaced from the arrestment system by new tapes. The aged tapes were closely examined to identify the various types of tape damage. New tapes are initially 8 in.

wide, 0.344 in. thick, and 483 ft. long. For the test, aging arresting gear tape was cut into specimens 26 in. and 30 in. long and grouped into two damage categories, edge fray damage and transverse damage. Figure 6 shows an example of typical arresting gear tape.

TEST APPARATUS The tests of the arresting gear tapes were conducted on a 120 000-1b load-testing machine (fig. 7). The setup consisted of the 120 000-1b load-testing machine and a digital data acquisition system, which was used to capture the data during each test with a recording rate of 10 samples/sec. The testing machine consists of a hydraulic press and a sensitive load measurement system. The critical component to the success of the test was the grip fixture, which had to fit into each of the 3- by 4-in. top and bottom open slots of the testing machine as well as grip the tape specimen. Two identical grip fixtures were designed, one for the top mount of the testing machine and the other for the bottom mount. One end of the grip fixture was designed to fit into the open slots of the testing machine, and the opposite end was designed to fit the 8-in -wide arresting gear tape specimen. (See fig. 8.)

The tape grip fixture shown in figure 9 consisted of a center plate and two side plates.

The plates were mounted together at an angle by 1-in. bolts. When the tensile load increased, the clamping force of the side plates increased. The assembly of the specimen between the side plates consisted of two wedges that fit between the inside of the side plates and each side of the specimen. Sandpaper was used between the inside of the side plate and the wedge. Doublers made out of Union Carbide Bakelite material were attached to the specimen prior to testing to help reinforce the tape edges.

TEST PROCEDURE The test procedure involved three main steps. The first step involved preparing the specimen for testing. The preparation consisted of making doublers out of Union Carbide Bakelite material. The process involved bonding the doublers to the tape by applying epoxy to the edges of the tape specimen and curing the epoxy for at least 6 hr prior to testing.

Step two was the assembly of the grip fixture and the tape. The tape specimen was assembled to the grip with wedges and sandpaper, fitting the specimen between the wedges and the side plates and bolting together with 1-in. bolts on each side of the specimen. Two bolts on each side of the specimen were tightened to clamp the specimen in the grip fixture.

The grip fixture clamped each end of the specimen using up 2 in. of specimen. Step three involved attaching the grip fixture to the testing machine. The narrow end of the grip fixture was placed in the open slots of the top and bottom mounts and held together by 2-in. bolts.

(See figs. 7 and 8.)

The testing machinewas set to the maximum load capacityof 120000 lb and a

displacement transducer wasmountedon the machineto measure deformation. A digital

dataacquisitionsystemwas usedto collectdataduring eachtest. Loads were applied

increasingly until failureoccurred or themaximumtravellengthon the testingmachinewas

reached.Most of the specimens failed atthe grip fixture. A challengewas developinga

fixturethatdid not causethe specimen to slip or fail at the fixture ends. The failure loads variedfrom 40206lb to 93 083lb. Figure10displaysa typicalfailed specimen.

RESULTS Fifteen arresting gear tape specimens were tested. The condition of the specimens ranged from transverse damage, simulated damage, and edge fray damage. The specimens were 0.344 in. thick and 8 in. wide with the exception of specimen 1 that was 7 in. wide, and the length was 26 in. for 13 of the specimens and 30 in. for the remaining 2. The geometry for each of the specimens tested can be found in table 1, but due to grip failure problems, only 3 tests showed tape failure and are discussed in the following paragraphs.

Specimens 12, 14, and 15, which exemplified tape failure, are now discussed. Figure 11 displays a load-displacement plot for specimen 12. The damage type for this specimen is transverse damage with minor edge fray. Specimen 12 failed at a maximum load of 69 048 lb. The minor discontinuity observed in the curve is possibly caused by internal fiber breakage of the specimen. Popping sounds were heard when the loads were approaching 20 000 lb.

A load-displacement plot of specimen 15 is shown in figure 12. Specimen 15 exhibited transverse damage as well and failed at a maximum load of 74 634 lb. The curve in the figure shows some minor discontinuity approaching 25 000 lb. During the test, popping sounds were heard near these loads.

A plot showing load displacement of a tape with edge fray damage, specimen 14, is in figure 13. This specimen failed at a maximum load of 40 206 lb. Popping sounds were also heard during this test. The specimen with edge fray damage failed at a much lower load than that of the specimen with transverse damage. Based on this observation, further tests should be performed because it is probable that the tapes with edge fray damage should be replaced sooner than the ones with transverse damage.

CONCLUDING REMARKS An experimental study was performed on damaged arresting gear tape specimens to determine their maximum tensile load strength capability. After several modifications to the grip fixture, a grip design was developed that was adequate to grip the 8-in. specimens and fit properly into the slots on the 120 000-1b load-testing machine. A methodology was established to perform continued evaluations of the aging arresting gear tapes in the future.

The specimens tested were characterized as exhibiting transverse damage and edge fray damage. The specimens with transverse damage failed at higher loads than the specimen with edge fray damage. This result suggests that if the arresting gear tape shows edge fray during the inspection procedure, consideration should be given to replacing the tape sooner than one with transverse damage. However, further tests should be conducted on specimens with both transverse damage and edge fray damage to acquire a larger data set before consideration is given to altering the inspection and replacement procedure.

One recommendation is if edge fray damage is detected and the damaged edges are trimmed, the trimmed edges should be treated with a polymer solution to help hold the fibers together to increase the tensile strength of the tape.

REFERENCE 1. Davis, Pamela A.; Stubbs, Sandy M.; and Tanner, John A.: Langley Aircraft Landing Dynamics Facility. NASA RP-1189, 1987.

Z_

_ e'l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l _ e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l e.l _ e.l e.l

###5.### • _ _#_#

c_ r_ c_

c_

c_

O

rJ_ (a) Edge fray (b) Transverse Figure 3. Types of damage.

o,-( .,-( _Q ;-I ;-I J_ _Q c_ °_.-4 Q.)

c_ ]] c_ v_ c_ -4nO c_

_o

._mq ._mq c_ C_ _o ii_!iiiiiiiiiii 0 i_iiiiiiiiiiiiii _ _::::::::::_::: :i:!:!:i:i:i_i:i _,_ :_:::_::::::::: c_ ]4 _mb c_ ..... iiiiiiiiiiiiiiiiiiiiiiii_ii_i_i_ii iii iii iiiiiiiiiiiiii iii iii iiiiiiiii i iiii iiiii Figure 9. Schematic of tape grip fixture and arresting gear tape specimen assembly.

Figure10. Arrestinggeartapefailure.

80000" 70000" 60000" 50000" _40000" d 30000" 20000" 10000" .

-1 0 1 2 3 4 5 6 Displacement, in.

Figure 11. Load-displacement plot for specimen 12 with transverse damage and minor edge fray damage.

70000" 60000" 50000" 40000- J 30000- 20000- 10000- -1 0 1 2 3 4 5 6 Displacement, in.

Figure 12. Load-displacement plot for specimen 15 with transverse damage.

80000- 70000- 60000- 50000- 40000- d 30000- 20000- 10000- -1 0 1 2 3 4 5 6 Displacement, in.

Figure 13. Load-displacement plot for specimen 14 with edge fray damage.

REPORT DOCUMENTATION PAGE Form Approved Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson DavisHighway_Suite12_4_Ar_ingt_n_VA222_2-43_2_andt_the__ice_fManagementandBudget_Paperw_rkReducti_nPr_ject(_7_4-_188)_ Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED December 1999 Technical Memorandum 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS An Experimental Investigation of Damaged Arresting Gear Tapes for the Langley Aircraft Landing Dynamics Facility WU 706-12-11-02 6. AUTHOR(S) Angela J. Mason 8. PERFORMING ORGANIZATION 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) REPORT NUMBER NASA Langley Research Center L-17768 Hampton, VA 23681-2199 10. SPONSORING/MONITORING 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) AGENCY REPORT NUMBER National Aeronautics and Space Administration NASA/TM- 1999-209839 Washington, DC 20546-0001 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Unclassified-Unlimited Subject Category 09 Distribution: Standard Availability: NASA CASI (301) 621-0390 13. ABSTRACT (Maximum 200 words) An experimental investigation was performed on damaged arresting gear tapes at the Langley Aircraft Landing Dynamics Facility. The arrestment system uses five pairs of tapes to bring the test carriage to a halt. The procedure used to determine when to replace the tapes consists of a close evaluation of each of the 10 tapes after each run. During this evaluation, each tape is examined thoroughly and any damage observed on the tape is recorded. If the damaged tape does not pass the inspection, the tape is replaced with a new one. For the past 13 years, the most commonly seen damage types are edge fray damage and transverse damage. Tests were conducted to determine the maximum tensile strength of a damaged arresting gear tape specimen. The data indicate that tapes exhibiting transverse damage can withstand higher loads than tapes with edge fray damage.

14. SUBJECT TERMS 15. NUMBER OF PAGES Tensile test, Arresting gear tape, Load testing, Aircraft landing dynamics 16. PRICE CODE A03 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION 17. SECURITY CLASSIFICATION OF THIS PAGE OF ABSTRACT OF ABSTRACT OF REPORT Unclassified Unclassified UL Unclassified NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. Z-39-18 298-102