T-33 Pitot-Static Calibration Technical Report AFFTC

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I• T-33 (SILVER STAR MK 3)PITOT-STATIC SYSTEM CALIBRATION

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FF

TCTHOMAS R. WOODFORD

Project Engineer

ERIC P. HANSEN, Major, USAF

Project Pilot

FINAL REPORT

8 JUNE 1985

APPROVED FOR PUBLIC RELEASE;

DISTRIBUTION UNLIMITED

AIR FORCE PLIHNr TEST CENTER

KDWARDS AIR FORCE BASKE CALIFORNIA

AIin FORCE SYSTiMS COMM AND

UIrTEID STATES AIN FORCE

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"This technical report, T-33 (Silver Star MK 3) Pitot-Static System Calibration, was submitted under Job Order Number

2591A0 by the Commender, 6510th Test Wing, Edwards AFB,

California 93523.

This report has been reviewed by th e Office of Public

Affairs (AFFTC/PA) and is releasable to the National Technical

Information Service (NTIS). At NTIS, it will be available tothe general public, including foreign nationals.

Prepared by: This report has been reviewed

and is approved for publication:

THOMAS R. WOODFORD MICHAEL . EM SON

Project Engineer Lieutenant Colcnel, USAF

Director, T-46A Combir.•dTe3t Force

JEX .'BEUTLER III

Colonel, USAF

Acting6Come stGroup

SATEN

Colonel, USAF

Commander, 6510th Test Wing

Major General, USAF

Comnmander

When U.S. Government drawings, specifications, or any other

data are used for any purpose other than a definitely relatedgovernment procurement operation, the government thereby incursno responsibility nor any obligation ihatsoever; and the fact

that the government nay haie foraul3ted, furnished or in any

way supplied the said drawings, specifications, or any other

data is not to be regarded by implication or otherwise, as in

any manner l icensing th e holder or any other person or

corporation or conveying any right or permission to

manufacture, use, or sell any patentend invention that may in

any way be related thereto.

Do no t return this copy; retain or destroy.



UNCLASSIFIEDfECURITY CLASSIFICATION OF THIS PAGE

tiEPORT DOCUMENTATION PAGE

ls REPORT SECURITY CLASSIFICATION lb . RESTRICTIVE MARKINGS

tUNCLASSIFUFD2& sECURITY CLASSIFICATICMN AUTHORIVY 3. OISTRISUTION/AVAILASILIVY OF REPORT

DOD 5200.1/AFR 7O-1I ... Apprc.'ed for public release;2b DECLASSIFICATION/DOWNGRAOING SCHEOULE distribution

unlimited4 PERFORMING ORGANIZATION REPORT NUMSER(S) S. MONITORING ORGANIZATION REPORT NUMAWIRS)

AFFTC-TR-85-19

6& NAME CF PERFORMING ORGANIZATION OFFICE SYMBtOL 7& NAME OF MONITORING ORGANIZATION

6510th Test Wing TE ASD/AFG

6c ADDRESS ICStY. SUNt and ZIP Codfl 7b. ADDRESS (City, SUNt dod ZIP Codr)

Air Force Flight Test Center Wright-Patterson AFB, Ohio 45433Edwards AFB, California 93523

Se. NAMC OF FUNOING/SPONSORING OFFICE SYISOL .PWROCUREMENT INSTRUMENT IDENlIFICATION NUMBERORGANIZATION fi t "0__,_WI

Sc ADDRESS Cty. Sisk and ZIP Code# oL.SouRCs OF FUNDING NoB.

PROGRAM PROJECT TASK WORK UNITCLIEMENT NO No. NO . NO .

,, TITLE l•-tn-a - .. ,tym,,oe&W*I . .. 63228 I 3-52T-33 (Silver Star WK 3) Pitot-Static (cont.)_

12. PERSONAL AUTHORIS)

Woodford, Thomas R.; Hansen, Eric P.jM'aor, USAF13. TYPE OF REPO0T meb.IM COVERED 14. DATE OATRPOO (Y,. M". Dol Sl PAGE COUNT

Final FROM17APR85 TO i 1985,Jsip-Ja•kL . 34if. SUf"LOEME1N'AIRY NOTATION

17 COSATI CODES IS SUBJECT TERMS ireat u @ It and ado-oIy 6V bo 0*06I

FIELD GROUP Sue. an. iAirspeed; - . -?PttotA'UbeS. -- -

01 03 Altitude. T-3301 04 Calibration T-46ABSTRACT Wont•oLane owft smte-enry a&dvuUmI y oWewber

This report presents the results of pltot-static system calibration testsperformed on T-33 (Silver Star W 3), civil registration number Nt3TB.The T-33 pitot-static system 'was calibrated in order to use the T-33 as a pacer forthe T-46A oitot-static systed calibration tests to be performed during the T-46ADevelopment Test and Evaluation Program. AX e test aircraft will perform satisfactorilyas a pacer, 4owever,9periedic checks on the pitot-static system's accuracy shouldbe performed. t., ,eA:,

20 DISTRISUTIONIAVAILABILITY GA ABSTRACT 21 ABSTRACT SECUMIT- CLASSIFICATION

UNCLASIFIECOUNLI•ITED SAME AS RPT. ] C-,C uS UNCLASSIFIED

22M NAME OV RESPONSIBLE INOIVIDUAL M TIELEPHONE NUMBER 22c OFFICE SYMBOL

Thoams R. oodford I*WAmCoehoas . Wodfrd(805) 277-045.8 TEVT

DO FORM 1473,83 APR 1 DIlON OF I JAN 73 IS OBOLETE

SECURITY CL&SSIFICATION OF THIlS PAGE

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SfCUAITY CLASSIFICATION OF THIS PAGE

Block 11 cont.

System C3libration

1INCI ASSTF;Fr)SECURITY CLAMSIPCATION OF THIS PAGI



PREFACE

The T-33 (Silver Star MK 3) pitot-static systemcalibration tests were performed in support of the T-46ADevelopment Test and Evaluation (DT&E) program. The T-46A test

program waz directed by th e T-46ASystem Program Office(ASD/AFG) of th e Aeronautical Systems Division, Wright-

Patterson AFB, Ohio. The T-33 pitot-static system calibration

was required to enable the T-33 to function as a pacer fo r the

pitot-static system calibration of the T--6A.

The author thanks Mr. Frank Brown and Mr. Al DeAnda fortheir technical assistance. The project pilots were Major Eric

Hansen and Major John Bush of the USAF.

[Accesion For

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TABLE OF COHTENTS

Page No.

PREFACE...............,.................................. 1

LIST OF ILLUSTRATIONS ............... . .... ..... 5

INTRODUCTION ..................... ................ ... 7

TEST AND EVALUATIO ..................................... 11

CONCLUSIONS AND RECOMMENDATIONS ......................... 17

REFERENCES ................................ 19

APPENDIX A: DATA REDUCTION OUTLINE ...................... 21

APPENDIX b: FLIGHT LOG ............................... * 27

LIST OF ABBREVIATIONS AND SYMBOLS ....................... 29

! 3

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4



LIST OF ILLUSTRATIONS

Figure Title Page No.

1 Pitot Tube and Static Port 8

1A Pitot Tul'e and Static Port (Detail) 9

2 Position Error Pressure Coefficient 13

3 Altitude Correction Due to Position Error 14

4 Airspeed Correction Due to Position Error 15

5 Mach Number Correction Du e to Position Error 16

Al Tower Fly-By Data Reduction 22

A2 Front Co.'-it Airspeed Instrument Correction 24

A3 Rear Cockpit Airspeed Instrument Correction 25

A4 Rear Cockpit Altimeter Instrument Correction 26

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INTRODUCTIý;a

This report presents the results of the T-33 (Silver StarMK 3) pitot-static system calibration tests. The tests were

conducted at the Air Force Flight Test Center (AFFTC), EdwardsAFB, California in support of the T-46A Development Test and

Evaluation (DT&E) Program. The pitot-static system calibration

tests were conducted between 17 April 1985 and 15 May 1985

during four sorties totaling 5.2 flight hours.

OBJECTIVL

The objective of this test was to obtain pitot-staticsystem calibration data for the T-33, civil registration N83TB,

in order that the aircraft could be used as a pacer in support

of the T-46A DT&E Program.

AIRCRAFT DESCRIPTION

The T-33 (Silver Star MK 3) was built by Canadair Ltd.,Montreal, Quebec, Canada. The aircraft was owned by

Thunderbird Aviation Inc. of Phoenix, Arizona and carried civil

registration N83TB. The aircraft was leased by the AFFTC as a

support aircraft fo r the T-46A DT&E Program. The production

pitot-static system was used. The system employed a dog-leg

pitot probe mounted under the nose on the aircraft centerline

approximately 32 inches aft of th e nose tip and two staticports symmetrically mounted on th e lower sides of the nose

approximately 35 inches aft of th e nose tip (see Figure 1 andIA). Calibrated, senujitive airspeed indicators were installed

in both cockpits and a calibrated, sensitive altimeter was

installed in the rear cockpit.

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PITOT TU

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FIGURE 1A PITOT TUBE AND STATIC PORT (DETAIL)



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TEST AND EVULUATION

TEST TECHNIQUE3

Tower fly-by and pacer data vere used to deteiinine theposition error. Reference 1 was used as a guideline for the

tests. Th e tower fly-bys were conducted using the AFFTC tower

fly-by facility. The position error was obtained from thedifference between the T-33 test aircraft's instrumentcorrected altimeter reading and th e aircraft's pressure

altitude determined by tower stadiametric observation.

Pacer data was obtained with an AFFTC calibrated pacer

aircraft (T-38A, S/N 70-1575). Both stabilized and

unstabilized pace techniques were used. During stabilized pace

the T-38 pacer flew in close formetion with the T-33 test

aircraftmaintaining

the same altitude and airspeed duringstabilized straight-and-level flight. The position error was

obtained from the difference between the T-33 test aircraft's

instrument corrected altimeter reading and the T-38 pacer'sinstrument and position error corrected altimeter reading.

An unstabilized pace technique was used to obtain data atspeeds lower than the T-38 pacer could maintain in stable one-g

straight-and-level flight (approximately 170 KCAS). The T-38pacer 3et up at the same altitude behind and to the side of theT-33 test aircraft. The T-33 stabilized at the test airspeed(less than 170 KCAS) and the T-38 pacer stabilized atapproximately 17 0 KCAS. Airspeed and altimeter readings were

taken as the T-38 pacer overaook the T-33 test aircraft at thesame altitude. The position error 2 obtained from thealtimeter difference as with the stabilized pect technique. Alldata from both aircraft were hand recorded. The front and rear

cockpit instrument readings in the pacer and the front and reartest aircraft airspeed readings were each -veraged to improveaccuracy.

DATA ANALYSIS

The altitude pozition errcrs determined from the testswere used for data analysis. Low resolution of the airspeed

indicators with respect to the small airspeed pusition errorresulted in large scatter in the position error data determinedfrom the airspeed difference during stabilized pace. Thereforethe airspeed difference was not used for analysis. The

position error pressure coefficient ZAPf/qci : position errorpressure/indicated differential pressure? was calculated frim

the altitude position error and is shown in Figure 2. rhe

scatter in the low speed data (especially the 20 degree flaps

data) was largely due to the degraded accuracy of the

unstabilized pace method.

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The fairings of Figure 2 were used to devclop fairings for

Figures 3 through 5. The alti tude position brror (AH c)determined during the tests is shown in Figure 3. The airspeed

po-oition error (L& c) calculated from the alti tude position

error is shown in Fgure 4. The Mach number position error

"(U-1 ) calculated from the altitude position error is shown in

FigUre 5. The data reduction outline is contained in AppendixA.

In order to insure the accuracy of the pitct-static system

calibration, periodic checks should be performe~i. A l imitednumber of tower fly-by passes should be performed periodically

to verify the pitot-static system calibration accuracy.

(Recommendation 1) The ancuracy of the airspeed indicators and

altimeters should be checked periodically to insure accurate

pitot-static system data, (Recommendation ?)

12

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CONCLUSIONS AND RECOMMENDATIONS

Accurate calibration data were obtained fo r th e T-33(Silver Star MK 3), civil registration N83TB, by the tower fly-by and pacer techniques. The accurate calibration of th e

pitot-static system will allow the use of the T-33 as a paceraircraft for support of th e T-46A Development Test and

Evaluation Program. In order to insure the continued accuracy

of the pitot-static system calibration, periodic checks shou]d

be performed.

1. A limited number of tower fly-by passes

should be performed periodically to verify

the pitot-static system accuracy. (page 12)

2. The accuracy of tVe airspeed indicators and

altimeters should be checked periodically to

insure accurate pito' static system data.(page 12)

17



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REFERENCES

1. DeAnda, Albert G., AFFTC Standard Airspeed CalibrationProcedures, AFFTC-TIH-81-5, Air Force Flight Test Center,Edwards AFB, California, June 1981.

2. Hart, Ronald E., Airspeed Calibration Reduction Program forthe ZiO Computer, Office Memo, Air Force Flight Test Center,Edwards AFB, California, September 1984.

19

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APPENDIX A

DATA REDUCTION OUTLINE

ToW;,,FRFLY-BY ANALYSIS

rne tower fly-by analysis assumed that the tapeline

altitude differences between the ramp, tower and fly-by

altitude equaled the equivalent pressure altitude differences.

No significant error was introduced by this assumption because

of the relatively small altitude differences.

The zero-grid-line pressure altitude (HO was determined

by the ground block method as follows (see Figure Al):

Hy = Hi c- -Lhx +Lhxy

where: Hi = Ground Block Instrument Corrected Altimeteric~ Reading

hx= eight of Altimeter Above Ramp (6 feet)

/ hxy = Height of Tower Eyepiece Above Ramp

The height of the aircraft above the zero-grid-line C.hy

was determined as follows:

hy = K x G.R.

where: K : Geometric Constant (31.5 feet/inch)

3.R. = Grid Reading (inches)

The altitude position error was then calculated:

H 11 + /'h -H.pc y y icy

where: Hicy Instrument corrected aircraft altimeter reading

Several ground block readings were taken before and after

the flight and atmospheric pressure was monitored in the fly-by

tower during the tests in order to account for atmospheric

pressure variation during the duration of the test flight. No

atmospheric pressure variations were observed during tht

subject tests.

21



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PACER ANALYSIS

The altitude position error was calculated using the pacerk ~Mct-hod as follows:

L1 C ic tet - HC ce

rwhere: H.its = Test aircraft instrument corrected altitude

H pcr=Pacer aircraft calibrated pressure altitude

The instrument corrections for the T-33 test aircraft'scalibrated instruments are shown in Figures A2 through A4.

The equations outlined in Reference 2 were used for

subsequent data reduction.

23

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26



APPENDIX B

FLIGHT LOG

Date Duration Crew Pacer Crew Test

17 APR 85 1.2 hr Hansen/Edmondson -- Fly-by

18 APR 85 1.4 hr Bush/Edmondson Fly-by

14 MAY 85 1.2 hr Hansen/Woodford Deehan/Waniczek Pacer

15 MAY 85 1.4 hr Hansen/Bjurstrom Luczak/Woodford Pacer

:," 27



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LIST OF ABBREVIATIONS AND SYMBOLS

item Definitions Units

AFFTC Air Force Flight Test Center -

DT&E Development Test and Evaluation

G.R. Grid Re3ding

He Pressure Altitude, Calibrated feet

Hic Altimeter Reading, Instrument Corrected feet

Hicx Ground Block Altimeter Reading, feet

Instrument Corrected

Hic" Fly-By Altimete. Reading, feet

•yInstrument Corrected

H Ramp Pressure Altitude feet

Hy Zero-Grid-Line Pressure Altitude feet

K Geometric Constant feet/inch

KCAS Knots Calibrated Airspeed knot!

MK Mark -

PPressure inches Hg

qcic Differential Pressure inches Hg

S/N Serial Number

T Trainer

Vic Indicated Airspeed, Instrument knots

Corrected

LH Altitude Position Error Correction feetPC

Ahx Height of Altimeter Above Ramp feet

Lhxy Height of Tower Eyepiece Above Ramp feet

L~h Height of Aircraft Above The Zero- feety Grid-Line

-"Mpc Mach Number Position Error Correction

PC_pPosition Error Pressure inches Hg

LV Airspeed Position Error Correction knots

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T-33 Pitot-Static Calibration Technical Report AFFTC