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FROMDistribution authorized to U.S. Gov't.agencies only; Test and Evaluation; FEB1974. Other requests shall be referred toTactical Fighter Weapons Center, NellisAFB, NV.

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TAC USAF ltr, 30 Apr 1975

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TAC PROJECT 73C-014F

pD final ReportBSU-1lA/B CONICAL FIN IOT&E

(CONSTANT BRACKET)

February 1974

Distribution is limited to US Government agenciesonly because this document covers the test and-evaluation of military hardware (February 1974).Other requests for this document must be referredto HQ TAC/DR, Langley AFB, VA 23665.

TACTICAL FIGHTER WEAPONS CENTER ITAC)

NEWS AIR FORCE BASE, NEVADA

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TAC PROJECT 73C-014FI!BSU-IIA/B CONICAL FIN IOT&E

(CONSTANT BRACKET)

FINAL REPORT

February 1974

Prepared by: LELIAN D. McCOY, Lt Col, USAFProject Manager

Submitted by: WILLIAM A. McCOLLUM, Lt Col, USAFDCS, Test and Evaluation

Approved by: ONF 24 S SAFCommander

This report has been reviewed and approved byHeadquarters Tactical Air Command.

Distribution is limited to US Government agenciesonly because this dokument covers the test andevaluation of military hardware (February 1974).Other requests for this document must be referredto HQ TAC/DR, Langley AFB, VA 23665.

TACTICAL AIR COMMANDUSAF TACTICAL FIGHTER WEAPONS CENTER

NELLIS AIR FORCE BASE, NEVADA

A __

----- I-II I- --I _ -_ [ : _ --

FOREWORD

This Initial Operational Test and Evaluation was conducted by authorityof AFR 80-14, TACR 55-10, and TAC Project Order 73C-014F, April 1973.Active testing began 30 May and ended 24 September 1973. This test wasmanaged by the United States Air Force Tactical Fighter Weapons Center,Nellis AFB, Nevada, and conducted by the 422d Fighter Weapons Squadron,Nellis AFB, and the 4485th Tactical Test Squadron, Eglin AFB, Florida.

The following personnel were responsible for the conduct of the testand preparation of the final report:

TAC Project Officer R. N. PARKER, Capt, USAFHQ TAC/DRAR

IOT&E Project Manager L. 0. McCOY, Lt Col, USAFUSAFTF1WC/TEM

Unit Project Officer D. JACOBSEN, Maj, USAF422 FWSq/DO

Project Coordinator F. BURDETTE, Lt Col, USAFUSAFTAWC/TEFA

Operations Analyst S. N. GREEIIHALGH, Civ

USAFTFWC/OAThe assistance by personnel of the 4485th Tactical Test Squadron is

gratefully acknowl edged.

PM ~EDIIC ?A= BLKT]

j

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SUMMARY

The BSU-11A/B Conical Bomb Fin was designed as a replacement for theMAU-93/B Fin currently used on the MK 82 low drag general purpose bomb.The purpose of this evaluation was to determine the operational suit-ability, effectiveness, and limitations of the BSU-11A/B, with particularemphasis on comparing it to the MAU-93/B. Testing, consisting of manualdeliveries of inert MK 82 bombs with BSU-IIA/B and M'AU-93/B fins, wasmade atdive angles of 15, 30, and 450 on the Nellis ranges, and a dynamicstability study was performed at Eglin AFB. Additionally, all aspectsof ground handling and buildup were evaluated, including a timed build-uptest and an F-1ll aircraft fit check. It was concluded that the quick-attach bolt and clamp mechanism of the BSU-llA/B was unsatisfactory forfield use. Statistically, there were no significant differences indispersion and accuracy of the BSU-llA/B and the MAU-93/B; however, varia-tion in ballistics may become significant in high-time-of-fliht deliveries.Stability characteristics were the same; and a 44 percent build-up timewas saved with the BSU-IIA/B. It was recommended that the BSU-lIA/Bnot be accepted for field use until the quick-attach bolt and clampmechanism is redesigned.

i

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TABLE OF CONTENTS

Page

Foreword ........................................... iSummary ............................................ vTable of Contents ...... .. i.i............. vi iList of Illustrations .............................. ixList of Tables ..................................... ixAbbreviations, Symbols, and Defini .iors ........... xi

Paragraphs

1. Introduction ............ ......2. Purpose of the IOT&E.................. .3. Method of Accomplishment .......................... 34. Results and Discussion ......................... C5. Integration into Force Structure .................. 196. Conclusions ....................................... 197. Recommendations ........................... . .. 20

vii7

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LIST OF ILLUSTRATIONS

Figure Page

1 Conical Bomb Fins .................................... 22 F-4 Loading Configurations ................ 53 Variation of Spin Rates in BSU-llA/B and MAU-93/B

Bomb Fins ....................................... ..... 84 Fit Test Clearance of BSU-llA/B Bomb Fins on Station

3 (BRU-3 Rack) of an F-ill .......................... 105 Quick-Attach Bolt and Clamp Mechanism on

the BSU-IlA/B Bomb Fin .............................. 18

LIST OF TABLES

Table Page

1 Release Parameters Evaluated Nellis AFB)........... 42 Release Parameters Evaluated (Eglin AFB)............. 63 Bomb Fin Dynamic Stability Study .................... 74 Bomb Spin Rates Summary ............................. 75 Timed Build-Up Test .............................. 116 BSU-11A/B Finned Bomb (Delivery Accuracy Versus

Altitude and Dive Angle) ............................ 137 BSU-IIA/B Finned Bombs (Delivery Accuracy Versus

Release Airspeed) ........................ . 148 MAU-93/B Finned Bombs (Delivery Accuracy Versus

Release Angle, Airspeed, and Altitude) .............. 159 Paired Delivery Impacts (MK 82/BSU-llA/B Versus

MK 82/MAU-93/B) ..................................... 16

ix

4rW

ABBREVIATIONS, SYMBOLS, AND DEFINITIONS

ADTC ............ Armament Development and Test Center

AGL ............. above ground level

alt ........ ... altitude

CEA ............. circular error average

CEP ............. circular error probable

deg ............. degree(s)

DEP ............. deflection error probable

ft .............. feet

G ............... gravitational force(s)

IOT&E ........... initial operational test and evaluation

KTAS ............ knots true airspeed

MER.......... multiple ejection rack

MIL STD ......... Military Standard

MPI ............. mean point of impact

MPID ............ mean point of impact in deflection

MPIR ............ mean point of impact in range

OOAMA ........... Ogden Air Materiel Area

REP ............. range error probable

Rev/Sec2........revolutions per second per second

TAWC ............ Tactical Air Warfare Center

TO .............. technical order(s)

. ............... degree(s)

............... inches

xi PMEDIta PAUE BLAK-NOT -yM=

FINAL REPOnRT

TAC PROJECT 73C-014F

BSU-11A/B CONICAL FIN IOT&E(CONSTANT BRACKET)

1. INTRODUCTIOU.

a. Operational Requirement. The ESU-IIAIB conical fin was designedto provide improved features over the currently used MAU-93/B. An AirForce decision to Initiate any quantity production of the BSU-IIA/Bwould be predicated on an ultimate gcal of 100 percent conversion from

the MAU-93/B to the BSU-IIA/B. Evalu~tion by both Tactical and Strategic

Air Commands was necessary as a basis for that decision.

b. Operational Concept. The BSU-IIA/B cenical fin was envisioned

as a replacement for the MAU-93/B as the stabilizing device on the M4K 82for all low drag dellv~rles.

c. hardware Description.

(1) The 14K 82 is a streamlined, steel-cased bomb; IO.E inches

in diameter; it has ar overall length of 91.3 inches with the BSU-IIA/Bfin assembly Installed, and weighs 531 pounds. Inert (concrete filled)14K 82s were used fcr this test.

(2) The BSU-IIA/B conical fin assembly consists of an elongated

cone with fins mounted 900 to each other, and is constructed of heavy-gauge steel with riveted jolnis. The assembly is fastened to the rear

of the bomb by a quick-attach ring ard one Allen head bolt. A fuze

access hole IS orevided, with an access plate secured by one fastenerand a "tuck-under" feature on the forward end, instead of the three

fasteners used on the .U-93/B. The BSU-IIA/B weighs the same as theMAU-93/0 (21 pounds), is the same length (26-1/8 inches), has the samefin span (15-1/8 Inches), and provides the same bomb center of gravity;

however, the BSU-IIA/B has a greater fin area than the MAU-93/b. Both

fins, with fuze access plates installed, are shown for comparison InFigure I.

2. PURPOSE OF THE IOT&E.

a. Scope. The scope of this evaluation was to determine the opera-tional suitability, effectiveness, and limitations of the BSU-IIA/Bconical fin under an operational, stockpile-to-target sequence on those

aircraft stations representative of all MK 82 carriage/release conditions.

b. Critical Questions and Issues. Not applicable.

' I

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___ _ ____

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c. Specific Objectives.

(I) Objective A. Determine 1he suilability of the BSU-IIA/Bconical fin on the MK 82 when operationally employed using standardstorage, buildup, handling, loading, carriage/release procedures, andtactics/techniques during combat and training type operations.

(2) Objective B. Determine the comparative ease of attachment,handling, loading, and bomb fuzing, with emphasis on safety considera-tions.

(3) Objective C. Determine adequacy of available, storage, hand-ling, loading, explosive ordnance disposal (EOD), and fligri manuals/procedures.

(4) Objective D. Determine any deficiencies/limitations duringall phases of operational employment.

(5) Objective E. Identify any unique training requirements.

(6) Objective F. 'Verify bcmb in-flight stability, dispersion,and accuracy characteristics.

(7) Objective G. Verify structural integrity during all phasesof operational employment.

(8) Objective H. Verify ballistics data.

(9) Objective I. Verify reliability/effectiveness.

(10) Objectie J. Identify any system or procedural improve-ments to enhance conical fin capabilities.

(11) Objective K. Identify any requirements for additionaltesting.

(12) Objective L. Identify any qualitative advantages and dis-advantages of the BSU-IIA/B versus toe M.AU-93/B fin.

3. METHOD OF ACCOMPLISHMENT.

) a. IOT&E Environment. This evaluation was conducted at Hellis AFB,Nevada and Eglin AFB, Florida. The F-4E aircraft was the primary testvehicle, with two sorties flown using an F-105D and six sorties utilizingan F-4D. The six F-4D sorties were flown at Eglin AFB. Munitions buildupand aircraft loading were accomplished In accordance with standardtechnical order (TO) procedures.

3

b. Method of Test.

(I) Nellis AFB.

(a) Nineteen F-4E test sortles were flown to drop 141MK 82/BSU-I A/B bombs and 19 MK 82/MAU-93/B bombs, using tha parameterslisted in Table I dnd configurations shown in Figure 2.

Table i. Release Parameters Evaluated (Nellis AFB).

Dive Angle Altitude Airspeeds(Degrees) Type Release* (Ft-AGL) (KTAS)

15 S & P 2,000 420S 2,000 480S 2,000 540

30 S 3,000 440R 4,000 480

S & P 3,000 500S 3,000 560

45 S 5,000 440S 5,000 500R 6,000 520

S & P 5,000 560s & P 5,000 580

* S= Manual Single

P = Manual PairR = 60 Millisecond Ripple

(b) A fit test was performed by loading four inert .149 82/BSU-IIA/B bombs on the BRU-3/A rdck of an F-Ill. The bombs were con-figured with inert M-904E2 nose fuzes and the ATU-,35A/B siie-driveassemh ies.

(c) A build-up test was made to obtain comparative timesfor buildup of the MK 82/BSU-IIA/B and the MK 82/MAU-93/B configurations.

(d) Two captive flights were made with six MK 82/BSU-IIA/Bbombs loaded on the centerline of an F-105D. Fin structural integrityand aircraft stability were checked during this portion of the test.

(2) Eglin AFB. Six F-4D sorties were flown, dropping a totalof 24 MK 82 bombs using parameters shown in Table 2. Twelve bombs wereconfigured with the BSU-IIA/B, and the other 12 with MAU-93/B. Photo-theodolite tracking and computer analysis were utilized to determine andcompare in-flight stabill'ty of the two types of fin.

4

Configuration

Configuration 8W R

S V 7

Configuration ,i v W V

VR6

-0 " 600-gallon Centerline Tank W - Painted White

' -.J 370-gallon tanks R - Painted International

S • MK 82/BSU-I IA/B Orangeo MK 82/MAU-93/B

Figure 2. F-4 Load Configurations.

Table 2. Release Parameters Fvaluated (Eglin AFB).

Dive Angle Altitude Airspeed(Degrees) Type Release (Ft-AGL (KTA

0 Manual Single 5,000 400

4. RESULTS AND DISCUSSION.

a. Operational Suitability.

(I) Capability to Fulfill Requirement.

(a) The BSU-IIA/B was capable of maintaining the stabilityof the MK 82 bomb during all tictical deliveries. The results of thedynamic stability study, conducted by Tactical Air Warfare Center (TAWC)and Armcment Development and Test Center (ADTC) at Eglin AFB, are shownin Table 3. There were 12 effective BSU-IIA/B finned bombs and IIeffective MAU-93/B finnec bombs dropped. Single releases were madefrom level flight at 5,000 feet above ground level (AGL) and 400 knotstrue airspeed (KTAS). The bombs were carried separately on MAU-12 racks,which were modified to Impart an extreme nose-down pitch (to the bombs)when releasedin an attempt to induce oscillations. Phototheodolitecameras tracked each bomo and the data were reduced to ottain spaceangle (angle between the axis and trajectory of the bomb) throughout thetime of fall. The values shown in Table 3 are averages o' all bombsdropped. From the data, there was no significant difference in thedynamic stability of the two fin types; that is, their ability to dampenout induced oscillations.

(b) A sampling was made of spin rate buildup during thefirst 4 seconds after release to determine spin acceleration of thebombs1 . In all cases, *the spin acceleration was linear with time,but varied considerably for both fins. The results of the study areshown in Table 4 and a graph Is shown in Figure 3. No correlationwas found between spin acceleration and release airspeed and/or altitude.The MAU-93/B fins possessed a much wider variance in acceleration charac-teristics than the BSU-IIA/B.

(2) Operational Compatibility Wlth Concepts, Doctrines,and In-Being Systems. The BSU-IIA/B was operationally compatible

ISpin acceleration is critical during the first 4 seconds after releasefor any fuze utilizing zero G sensing for arming.

6

'!I

Table 3. Bomb Fin Dynamic Stability Study.

BSU-HA/B MAU-93/BSpace Anle* SpeAne*

Time from Average o~f Average of -Aeragof AverageoRelease Maximum Angle Minimum Angle Maximum Angle Minimum Anglc(Seconds) (Degrees) (Degrees) m (Degrees)

1-3 18 1 17 1

3-5 7 2 6 1

5-7 5 i 4 1

7-9 4 1 4 1

9-11 6 1 6 1

11-13 11 2 7 2

13-15 9 5 6 3

15-Impact 8 1 5 1

kThe angle is between the axis and trajectory of the bomb. Therecould be a ± 30 error, and accumulative errors could be as highas V.

Table 4. Bomb Spin Rates Summary.

Release to Plus 4 Seconds, " 'Spin Accele'ration (Rev/Sec4 )

Fin Type Sample Size Low Average High

) SU-11A/B 11 0.65 0.94 1.23

4U-93/B 5 0.48 1.22 2.50

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(a) Nose fuzing was unchanged when the BSU-IIA/B finwas used. When loaded In tandem, nose-tail clearance was identical withthe MAU-93/B. The tail fuze access hole in the BSU-IIA/B was smallerthan that of the MAU-93/B; however, there was sufficient clearance forloading all existing tail fu~es. The ATU-35 side-drive access holewas identical In position, size, and shape in both fins. Thr tailfuzing procedures with the BSU-IIA/B installec were unchanged from ThCseused with the MAU-93/B.

(b) During the fit test performed on the F-Ill, the onlystation where the BSU-IIA/B had reduced clearance from that of the

rMAU-93/2 was on the rear shoulder stations of the BRU-3 rack on the out-board pylon wing stations 3 and 6. Minimum clearance between the BSU-IIA/B rear fin corners and the fully-extended flap (wings full forward)was 4.5 inches (Figure 4). This was well within clearance criteria ofMIL STD 1289. Nose-tail clearance between tandem bombs was unchanged.

(3) Operational Implication.

(a) Personnel/training requirements. Operational trainingrequirements for the BSU-IIA/B were identical to those used with theMAU-93/B. No requirements for new delivery procedures and techniqueswere identified during the test.

(b) Flight manuals.

I. TO IF-4C-34-1-1. Aircrew Weapons Delivery Manual(Non-Nuclear) will need to be revised to include reference to theBSU-IIA/B if adopted.

2. TO IF-4C-34-1-2. Aircrew Weapons Delivery Manual(Non-Nuclear) ballistic tables will need to be validated over the entirespectrum of release parameters for accuracy if BSU-IIA/B is adopted[see paragraphs b(1)(b) and (c).

j 3. All Aircrew Weapons Delivery Manuals (Non-Nuclear)for aircraft that carry the MK 82 will need to be revised and validated.

(c) Flight safety. The only flying safety factor identi-fied was the possibility of the BSU-IIA/B fin being lost off a bomb inflight due to failure of i- single retaining bolt [refer to paragraph4cM3

(4) Loqistical Supportability.

(a) Special facilities. The facilities to maintain, test,and logistically support the BSU-IIA/B are similar to those required forthe MAU-93/13.

-. -~ Wing Flap

BSU-11A/B A-3/

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t4-904E2 Fuze

410

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(b) Maintainability. No unique problems were revealed;however, the retaining bolt on the BSU-IIA/B musi be changed if it isbrought back from a flying mission. This is an undesirable feature[reference paragraph 4c(3)].

(c) Support and test equipment. No special support equic-ment was required.

(d) Personnel/training requirements. Other thar bomb build-up, all handling, loading, and delivery procedures for the BSU-IIA/B areidentical to those currently used with the MAU-93/B; therefore, no uniquetraining requirements existed. Build-up crews were favorably impressedwith the time saving features of the eSU-IIA/B. Build-up times werecompared by attaching BSU-IIA/B and MAU-93/B fins on MK 82 inert bombs.The same crew, consisting of five personnel including one supervisor,was used to build-up 36 bombs, 18 for each type of fin. The Lrew hadextensive experience with the MAU-93/B, but no operational experience withthe BSU-IIA/B (outside of a familiarization session). The BSU-IIA/B finsfor this test were packed in individuai cardboard shipping boxes, whereasthe MAU-93/B fins were packed (50 each) in palletized containers. Sincethe BSU-IIA/B will be shipped in palletized containers should itbecome a production Item, time required for unpacking the fins wasdisregarded and all fins were removed from packing containers beforethe timing was started. Hand tools were used and the crew was briefedtc work at normal speed. The results of the build-up test are shownIn Table 5. A time saving of 44 percent was realized as a result ofthe quick-attach ring on the BSU-IIA/B, and a single attachment boltversus the six set screws of the MAU-93/B.

Table 5. Timed Build-Up Test.

Type Fin Time to Build-Up 18 Bombs

BSU-11A/B 14 Minutes, 3 Seconds

14AU-93/B 25 Minutes, 18 Seconds

(e) Technical manuals. Changes to technical manuals would

be required if the BSU-IIA/B is adopted.

(f) Mobility. Not applicable.

(g) Ground sa-ety. The BSU-IIA/B has 127 inches of finedges compared to 73 inches on the M1AU-93/B. These edges are sharperon the BSU-IIA/B and run the full length of the fin assembly (Figure I),necessitating r,ore careful handling by servicing personnel during build-up and loading to avoid unnecessary cuts and skin abrasions.

II

b. Operational Effectiveness.

(I) All BSU-IIA/B finned bombs that were dropped et Nelli, onthe single and paired releases contributed to a data sample of 118 effec-tive bombs. The MAU-93/B finned bombs t,.jt were dropped on the palretreleases resulted in a data sample of !6 effective bombs. One of eachtype of bomb was not effective due to release sysiem malfunctions and/orimproper switch settings.

(a) The bomb impact data were analyzed by type of munitionanu delivery parameters to find any significant differences betweeneither accuracy or dispersion of the two fin types. Tables 6, 7, and 8contain the reduced data from which these analyses were made. Statisti-cal tests were conducted at the 90 percent confidence level 2 , using theCentrRl Limit Theorem and the Student's t-Distribution. These testsindicated that there was no significant difference between the accuracyor dispe-sion of the 118 BSU-IIA/B MK 82s delivered and that of the 16MAU-93/13 MK 82s. The tomb deliveries were also evaluated by deliveryaltitude, airspeed, and dive angles; and again, no significant trendswere indicated.

(b) On paired drrps, the BSU-IIA/B finned bombs hit longfor an average of 11.3 feet (Taole 9) when compared to the MK 82/fAU-93/Bimpacts. Although this difference was statistically insignificant atthe tactical delivery altitudes used, a trend was indicated which maybecome important at higher altitudes. In light of this apparent trend,a verification of ballistic tables is in order if the BSU-IIA/B isadopted (see Table 9). No other differences in flight characteristicsof the two fin types were evident during the paired drops.

(c) On the 12-bomb (one MAU-93/B and II BSU-IIA/B finnedbombs) ripple release from a 300 dive angle, a pattern length of 377feet was obtained. This compares to a length of 176 feet given in theballistic tables In TO IF-4C-34-I-2 for MAU-93/B finned bombs. ThelIst two bombs in the drop pattern had excessive spacing from the restof ihe group. On the 12-bomb ripple from 450 dive, the pattern lengthwas 212 feet. This compares to a given pattern length of 125 feet.The Impact pattern from the 450 drop was relatively uniform. In bothcases, the MAU-93/B finned bombs were released first ard impacted on theloading edge of the pattern with approximately average spacing from rhesecond (BSU-IIA/B finned) bomb. The cause of the increased patternlength over that given in the tables could not be determined becauseexact rolease parameters were unknown.

(d) Two captive flights were flown by an F-105D carryingsix BSU-IIA/B finned MK 82 bombs on the centerline multiple ejection

2The 90 percent confidence level was selected as a realistic criteriafor field/operational evaluations.

12

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Table 9. Paired Delivery Impacts (MK 82/BSU-11A/B VersusMK 82/MAU-93/B).

Release Parameters DistanceRelease Between BSU-111A/B

Dive Angle Altitude Craters Long *Airspeed (Deg) (Ft) (Ft) (Ft)

420 15 2,000 19 215 2,000 28 2615 2,000 20 1415 2,000 17 1115 2,000 20 4

500 30 3,000 39 3430 3,000 11 230 3,000 15 830 3,000 17 0

560 45 5,000 19 1445 5,000 26 1645 5,000 18 445 5,000 22 1545 5,000 27 8

Average 21.3 11.3

*In the direction of the line of flight, the M4K 82/BSU-l1A/B bombimpacted long with respect to the MK 82/14AU-93/B bomb.

16

Copy avIlable to DC does not_p61W fay I, ..... LA.1 UW G" "rack (MER). This aircraft and corfigu-ation was felf r) represen+ the

most severe stress environment that would be encountered on a +acti-aldircraft (luring subsonic maneuvers. Tne total -ime flown was 1.7 hnurs;44 minutes of the two flights were spent at M4ach 0.9, I,0C0 feet AGL,with numerous high gravitational force (G) turrs. The fin retainingblto, were changed afler the first flight and the fins wore inspectedafl,.r each flight. There was no indication of structur31 weakness ordanmd!e.

(2) The cnmparative effoctivenes, was as follows:

(a) The operational effectivenoss/reliabit;ty of theLISU-IIA/B was comparable to the MAU-93/B except as noted in paragraph4c beltw. Statistically, test results "indicated that the dive- bombingTlblob for Ihe MK 82 contained in TO IF-4C-34-1-2 are %,alid for- the[ISU-I IA/P finnid bombs. However, the long impact trand may become signi-ficant at hiilher delivery al titudes and zhould be investigated further.This evaluation did not attempt to examine the entire spectrum of parameterscont-ained in the bal-listic tables. No releases were accomplished above6,000 feet AL.

(b) There was no significant difference -in handling andloiding qualities between the two fins; however, the MAU-93/B tips cvereasily when placed tail down, since the tail cone extends beyond thefins. The BSU-IIA/B, on the other hand, was very stable because the finsextend slightly beyond the center cone (Figure I). This improved stabilit/is desirable since build-up operations will be in unimproved areas attimes. Standilg the fins tail-down Is a good 1m3thod to prevent dirt onddebris from being picked up on the forward mating surface.

(c) The only apparent advantage of the BSU-IIA/ overWthe t.IAU-93/13 was the time savings realized during fin attachment and

removal/replacement of the fuze access plate. The only disadvantages oftho BSU-IIA/B were the deficiencies outlined in paragraph 4c below.

c. Operational Limitations. The deficiencies or limitations found(luring the IOT&E were in the design of the quick-attach bolt and clampmechanism of the BSU-IIA/B (Figure 5).

(I) Prior to start of testing, a box of hardened steel boltswas received to replace the s-ainless steel bolts that came with thefins; the torque requirement given was 175 + 50 inch-pounds. A torqueof 170 inch-pounds was used on the first boibs bui It up. At thattorque, one bolt fai led and most of the others were distorted. An exami-ndtlon of the broken bolt reverled that it met the design hardness speci-fications, but had small fatigue cracks. Ogden Ai-r Materiel Area (OOAMA)

17

Itn

"41

U 4

18*

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Copy Vaiki-ble Ij DN,.

F l ~ PYAM "Jy k9"~ tewhc~reduced the torque range to 125 to 150 Inch-pounds, and allowed theoriginal stainless steel bolts to be used, provided the fin was checkedfor tightness after torquing. A torque of 130 inch-pounds was thenused; however, one of the stainless steel bolts broke at that torque.A subsequent examination revealed the bolt was faulty. The bolt proble, sseemed to be caused by the failure of the locking nut to seat itself flushon the quick-attach ring flange. This resulted from binding of the nutwing on the fin body as it s(Id abong while the bolt was being torqued.A constantly changing, bending torque was transmitted to the bolt becausethe nut was askew; consequently, the bolts failed at a relatively lowtorque. However, if the nut was kept flush aaainst the quick-attachring flange as the bolt was screwed In, no problems occurred. After thistechnique was discovered, no further bolt failures were experienced.

(2) During the routine buildup, one additional problem occurredwhich contributed to bolt/attachment deficiencies: the bolt threadswere distorted by being forced against the side of the hole. This causeda false torque reading and resulted in the fin becoming loose duringpreloading handling.

(3) Director, Materiel Management/MfNTM4 message 062240Z Mar 73(Interim Inspection and Installation Procedures for the BSU-IIA/B Fin)contained a warning note: "The retaining band bolt Is restricted to oneflight. If fin and bomb are returned for some reason, the bolt will bereplaced." Interviews with pilots who had recent Southeast Asia combatexperience indicated that bombs were frequently returned. Thus, the one-flight restriction on the retaining band bolt Is highly undesirable, and afix is required if the BSU-IIA/B is to become a stock Item.

(4) Failure of the attachment bolt will result in the fin comingoff the bomb. For this reason, the problems associated with the bolt arecritical, and the design tested was unsatisfactory for field use.

5. INTEGRATION INFO FORCE STRUCTURE. To be supplied by TAC/XP.

6. CONCLUSIONS.

a. The BSU-IIA/B was suitable as a conical fin on the MK 82 whenoperationally employed.

b. There were no significant differences in handling, loading, fuzing,and safety requirements, and attachment of the BSU-IIA/B was accomplishedin approximately 44 percent less time than the MAU-93/B.

04c. Changes to present TOs would be required If the BSU-IIA/B Is adopted.

d. The quick-attach bolt and clamp mechanism of the BSU-IIA/B wasunsatisfactory for field use." Copy a~dcle tIo D10C does

19 -

MF T

r

e. There were no untque training requirements associated withthe BSU-IIA/B.

f. There were no significant differences in the dispersion, in-i flight stability, and accuracy characteristics of the BSU-IIA/B compared

to Ilie MAU-93/B.

9. Tie USU-IIA/B is structurally sound.

h. Statistically, the bal-listics tables in TO IF-4C-34-1-2 weresatisfactory for MK 82/BSU-IIA/B bombs using release parameters in TableI; however, a long impact trend was apparent.

i. The BSU-IIA/B reliability/effectiveness was degraded by adeficiency in its quick-attach bolt and clamp mechanism.

j. An effective design change will be required prior to acceptanceof the BSU-I IA/B.

k. A build-up test is necessary after recommended design changes'have been completed.

I. The only apparent advantage of the BSU-I IA/B was the time savingsrealized from the quick-attach feature and the fuze access plate.

7. RECOMMENDATIONS. It is recommended that:

a. The BSU-IIA/B not be accepted for field use until the quick-attach bolt and clamp mechanism is redesigned and operationally tested.'The hardware changes listed below should be examined as possible so-lutionsto ihis deficiency. (OPR: CSAF/XOOW).

(I) The quick-attach ring could be spring-loaded IN insteadof our. This may provide a fail-safe system. In case the bolt shouldbreak, the fin would not be lost as in the present design. This changewould probably require that load crews be provided with a simple spreadertool to open the ring as the fin is installed on the bomb.

(2) The locknut could be clamped to the quick-ait'ach ringflange by having three wings on the nut (instead .te one presentlyused) and clamping them to the' ring flange.

(3) The sharp edges on the holes through the ring flange couldbe rounded to prevent thread damage on the retaining bolt.

(4) The retaining boll strength and/or size could be i-ncroased.

b. The adequacy of the ballistics tables above 6,000 feet AGL for MY82/BSU-iIA/B bombs be investigated if further testing is conducted.(OPR: AFATL/A)LYE),.

20

e7

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSBEFORE COM PLETING FOR.M

1. REPORT NUMBER 2. GOVT ACCESSION No. 3. RECIPIENT'S CATALOG NUMBER

TA C PROJECT 73C-014F

4. TITLE (. nd Subtitle) S. TYPE OF REPORT A PERIOD COVERKD

BSU-IIA/B CONICAL FIN IOT&E FINAL REPORT(CONSTANT BRACKET) 30 May - 24 Sep 73

6. PERFORMING ORG. REPORT NUMBER

7. AUTNORfa) 8. CONTRACT OR GRANT NUMBER(&)

LELIAN D. McCOY, Lt Col, USAFProject Manager

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TAK

AREA & WORK UNIT NUMBERS

USAFTFWC/CCNellis AFB NV 89110

I', COTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE i

HQ TAC/DR February 1974 -

Langley AFB VA 23665 13.NUMBEROF PAGES14. MONITORING AGENCY NAME & ADDRESS(I1 different from Controlling Olle) 15. SECURITY CLASS. (at thls eport)

N/AIS. DECL A.SI FICATION/DOWN GRADING

SCHEDULE

I. DISTRIBUTION STATEMENT (of this Report)

Distribution is limited to US Government agencies only because this documentcovers the test and evaluation of military hardware (February 1974). Otherrequests for this document must be referred to HQ TAC/DR, Langley AFB, VA23665.

17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, It different tom Report)

I 18. SUPPLEMENTARY NOTES

19. KEY WORDS (Continue on reverse side If necessary and Identify by block number)

BSU-11A/B Conical Bomb Fin Quick-Attack Bolt and ClampF-4D, F-4E, F-105D and F-1ll Aircraft

MAU-93/B FinMK 82 Low Drag General Purpose Bomb

20. ABSTRACT (Contlnue on reverse olde II necessary and Identify by block number)

The BSU-llA/B Conical Bomb Fin was designed as a replacement for the MAU-93/Bfin currently used on the MK 82 low drag general purpose bomb. The purpose ofthis evaluati.on was to determine the operational suitability, effectiveness,and limitations of the BSU-IIA/B, with particular emphasis on comparing it tothe MAU-93/B. Testing, consisting of manual deliveries of inert MK 82 bombswith BSU-lIA/B and MAU-93/B fins, was made at dive angles of 15, 30, and 450on the Nellis ranges, and a dynamic stability study was performed (continuEd)

DD I J 1473 EDITION OF 1 NOV65 IS OBSOLETE UNCLASSIFIEDSECURITY CLASSIFICATION OF THIS PAGE ("en Date Entered)

UNCLASSIFIED3rCz. ITY CLAiSIFICATION OF THIS PAGI(ne, Data Entod)

20. ABSTRACT (Continued)

at Eglin AFB. Additionally, all aspects of ground handling and buildup wereevaluated, including a timed build-up test and an F-ill aircraft fit check. Itwas concluded that the quick-attach bolt and clamp mechanism of the BSU-1lA/Bwas unsatisfactory for field use. Statistically, there were no significantdifferences in dispersion and accuracy of the BSU-llA/B and the MAU-93/B;however, variation in ballistics may become significant in high-time-of-flightdeliveries. Stability characteristics were the same; and a 44 percent build-uptime was saved with the BSU-IIA/B. It was recommended that the BSU-llA/B notbe accepted for field use until the quick-attach bolt and clamp mechanism isredesigned.

U A F

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