ESD-TR-67-293-VOL. I

A/RIA CATEGORY I FLIGHT TEST FINAL REPORT SUMMARY

NOVEMBER 1967

AEROSPACE INSTRUMENTATION PROGRAM OFFICE ELECTRONIC SYSTEMS DIVISION AI R FORCE SYSTEMS COMMAND UNITED STATES AIR FORCE L. G. Hanscom Field, Bedford, Massachusetts

Distribution of this document

is unlimited.

(Prepared under Contract No. AF 19(628)-4888 to Douglas Aircraft Modification Division, 2000 N. Memorial Drive, Tulsa, Okla. 74115.)

r-<--~------~--------------------------------------------------------------------------

LEGAL NOTICE

When U. S. Government drawings, specifications or other data are used for any purpose other than a definitely related government procurement operation, the government thereby incurs no responsibility nor any obligation whatsoever; and the fact that the government may have formulated, furnished, or in any way sup­plied the said drawings, specifications, or other data is not to be regarded by implication or otherwise as in any manner licensing the holder or any other person or conveying any rights or permission to manufacture, use, or self any patented invention that may in any way be related thereto.

OTHER NOTICES

Do not return this copy. Retain or destroy.

FOREWORD

A summary of the A/RIA category I Flight Test Program which was conducted during the period from 16 September 1966 to 25 May 1967, is presented herein. This report constitutes partial compliance to Data Item No. 59, T-19-53.0-1 of Air Force Contract No. AF 19 (628)-4888 awarded to Douglas Aircraft Modification Systems Division (2000 North Memorial Drive, Tulsa, Oklahoma 74115) by the Electronic Systems Division (ESD), Air Force Systems Command. The ESD cognizant office was the Aerospace Instrumentation Program Office (ESSIA), under the direction of Lt. Col. L. M. Politzer.

The test program was conducted by Flight Development personnel under the direction of the A/RIA Program Director, Douglas AMD, McDonnell Douglas Aircraft Corporation.

Publication of this report does not constitute Air Force approval of the reports finding or conclusions.

This technical report has been reviewed and is approved.

ii

ABSTRACT

This report summarizes the results of the A/RIA Category I Flight Test Program as reported under separate volumes (II, III, and IV) of ESD-TR-67-293. The major portion of the'flight tests were accomplished with three Apollo/Range Instrumented Aircraft (A/RIA) which .are modified C-135A airplanes now designated as EC-135N's. The test program encompassed aero-structural demonstrations of the A/RIA and A/RIA plus A-LOTS (Airborne Lightweight Optics Tracking System) configurations, plus evaluation of the basic C-135A subsystems which required modifications to support the EC-135N Prime Mission Electronics Equipment (PMEE). Test results demonstrated that: (1) The EC-135N modification was structurally sound; (2) Flying qualities of the EC-135N with and without the A-LOTS pod were comparable to the basic airplane; (3) Degradation in specific range due to theliA/RIA configuration was 5.8% and 14.2% in the A/RIA plus A-LOTS configuration; (4) The modified navigation and communication subsystems operated satisfactorily; and (5) The environmental control subsystems were adequate over the normal mission flight conditions. These test results verified that the C-135A as modified (EC-135N) can safely fulfill mission flight requirements and support the PMEE.

iii

Section

I

II

III

IV

Figure

1

2

3

4

5

6

7

8

9

10

11

TABLE OF CONTENTS

Introduction

Airplane Configuration

2.1 Test Vehicle Configurations

Summary of Flight Test Results

3.1 Flying Qualities 3.2 Structural Integrity 3.3 Performance 3.4 Modified Airplane Subsystems 3.5 PMEE Environment

Conclusions

LIST OF ILLUSTRATIONS

A/RIA Category I Flight Test Program

A/RIA Interior Arrangement

A/RIA Configuration

Trailing Wire Antenna Installation

A/RIA plus A-LOTS Configuration

A-LOTS Pod RQilloved and Aerodynamic Fairings Installed

Airspeed System Static Correction Comparison

Initial Buffet Boundary

Flight Envelopes

Compartment Temperature Distribution

Cruise Flight Sound Pressure Levels, EqUipment Compartment

v

Page

1

3

7

8

8 lD 13 14 15

19

Page

2

4

5

5

6

6

9

11

12

16

18

SECTION I

INTRODUCTION

The Douglas Aircraft Company, Aircraft Modification Division (AMD), received Contract AF 19(628)-4888 to modify eight (8) inventory C-135A aircraft to the Apollo/Range Instrumented Aircraft (A/RIA) configuration denoted as Model EC-135N. Four (4) of these aircraft were additionally modified to accept the Airborne Lightweight Optics Tracking System (A-LOTS), owned by Eastern Test Range (ETR). Under this contract, Category I Flight Tests were defined as all flight tests other than the Prime Mission Electronics Equipment (PMEE) tests, which were designated Category II Flight Tests. The prime objectives of ' the Category I Flight Test Program, results of which are summarized herein, were to prove the airworthiness of the A/RIA and A/RIA plus A-LOTS configurations, and determine that the aircraft sUb-systems modified to support the PMEE operated satisfactorily.

Four (4) A/RIA were utilized during the Category I Flight Test Program. The three (3) prime test vehicles were instrumented to obtain quantitative data for each phase of the test program as shown below:

AFSN

60-372 60-375 61-327

TESTS

Sub-system A/RIA Aero-structural A/RIA plus A-LOTS Aero-structural

Aircraft AFSN 61-330 was used to a minor extent in the SUb-system testing. Aircraft AFSN 60-372 was also the prime Category II test vehicle.

Approximately 192 flight hours were accumulated during this program which is graphically depicted in Figure 1. First flight was made on 16 November 1966, with the final flight being made on 25 May 1967. Both aero-structural phases of the program were conducted at Edwards Air Force Base, California, whereas the SUb-system flight tests emanated from AF Plant No.3, Tulsa, Oklahoma.

This report summarizes the highlights presented in the Category I Flight Test Final Reports previously published after each test phase was completed. For greater detail of the test results, refer to the following documents:

ESD-TR-67-293-Vol II

ESD-TR-67-293-Vol III

Category I Aero-Structural Flight Test Final Report (A/RIA Configuration)

A/RIA Category I Sub-Systems Flight Test Final Report

1

ESD-TR-67-293-Vol IV category I Aero-Structural Flight Test Final Report (A/RIA plus A-LOTS Configuration)

Results of the A/RIA Category II (PMEE) Flight Test Program were presented in the following report:

AFSN TESTS

60·372 , SUBSYSTEMS

DEV-3796 (DAC document control number) (The ESD TR number not assigned at this publication date.)

A I S I 0 I N I D

A/RIA System Category II Final Test Report

FLIGHT TEST TIME

J IF I M I A I M FLTS HRS ELAPSED

r PMEE INSTALLATION AND CHECKOUT 169 TOTAL, OF WHICH

(PERFORMED IN

E i~ ,1··. ~ II 31 APPROX.25 6MOS CONJUNCTION ' ' HRS,USED

" ::::::; WITH CAT. II IN SUBSYSTEM PMEE TESTING) ~. 1ST FLT· 19 SEPT 66 TESTS

60·375 i::::: t:::: :::;=:: ':

A/RIA ,t~: :::::::: :i:: : 30 85.7 61/2

AERO· lili i::: :::::::: WKS STRUCTURAL ~ 1ST FL T· 3 OCT 66

,: to; tm ' 61·327 71/2 A/RIA + ALOTS

: :, ::::::: 28 81.1 WKS

AERO-STRUCTURAL 1ST FL T· 20 MAR 67 ~.

MONTH - A I S I o I N I D J I F I M I A I M

YEAR 1966 1967

FIGURE 1. A/RIA CATEGORY I FLIGHT TEST PROGRAM

2

SECTION II

AIRPLANE CONFIGURATION

Eight (8) C-135A airplanes were modified to function as radio voice and data communication links between an orbiting Apollo space vehicle and the space vehicle control network. This modification to accomodate the A/RIA system prime mission electronics equipment (PMEE) included installation of several antennas, re-arrangement of the cabin area to house PMEE consoles and operators, and extensive changes in the electrical and air conditioning systems. The extent of the internal modifications is illustrated in Figure 2, A/RIA Interior Arrangement. Photographs illustrating the EC-135N external configu­ration are presented in Figures 3 through 6. The total modification package increased the EC-135N gross weight (no fuel) to approximately 20,000 pounds greater than the basic C-135A. Major installations and airplane changes included:

(a)

(b)

(c)

(d)

(e)

(f)

(~)

(h)

(i)

(j)

(k)

Nose radome and radome fairing installed. The radome houses a seven foot diameter VHF/UHF dish antenna and extends 12 feet 2 inches forward of the windshield center column.

R.F. probe antennas and associated fairings were installed on both wings at W.B.Lo 714.

Trailing wire antenna was installed along bottom fuselage centerline at Station 800.

Data Dump Antennas were located on bottom fuselage centerline at approximately Station 500.

Cabin floor panels were replaced with 3/8 inch plywood panels.

PMEE consoles and operators' seats were installed in the cabin area from Station 575 to Station 10500

Two rest areas, forward and aft, installed •.

Fuselage linings, honeycomb partitions and floor carpets were installed for noise absorption.

The electrical power system generators were replaced with four 40 KVA brushless generators, one on each engine.

Airplane air conditioning ducting was reworked to improve distribution to the PMEE operators and rest areas.

A gaseous oxygen system was installed.

3

." G) C l:J m !'J

2:: l:J

» z -I m l:J o " » l:J l:J » z G) m s: m Z -I

1000 1100

NO.1 - MISSION CO-ORDINATOR NO.2 - RECORD ,CONTROL NO.3 - ANTE;NNA CONTROL NO.4 - TELEMETRY CONTROL NO.5 - VOICE CONTROL NO.6 - H.F. CONTROL

I @ STA 772 @ STA 1008 @ STA 772 @ STA 596 @ STA 646 @ STA 825

~~~AREST-.j.~ _________ PMEE AREA ------------t----AFT RE~T AREA----.I

CAVITY

TRAILING WIRE ANT.

~VHFIUHF ANTENNA RADOME

FIGURE 3. A/RIA CONFIGURATION

TRAILING WIRE

ANTENNA DROGUE----..O

FIGURE 4. TRAILING WIRE ANTENNA INSTALLATION

5

/ /

r A-LOTS DOME

(HOTS POO

PLLOT'S SYSTEM PLTOT HEAO (PROTOTYPE EXTENSION)

~IGURE 5. A/ RIA + A·LOTS CONFIGURATION

\ \

\

FIGURE 6. A·LOTS POD REMOVED AND AERODYNAMIC FAIRINGS INSTALLED

6

Four of the A/RIA were also modified to carry the Airborne Lightweight Optics Tracking System. This modification consisted of:

(a) Addition of a B-50 sighting turret to the top of the airplane at fuselage Station 500;

(b) Installation of an A-LOTS control console at approximately Station 550;

(c) Rework of the cargo door to accept the A-LOTS pod; and

(d) A-LOTS pod which was 25 feet long with a maximum diameter of 5 feet (pod weighs approximately 3,930 pounds).

When the A-LOTS pod is not installed aerodynamic fairings are provided to Gover the sighting turret and pod attach fittings on the cargo door.

2.1 Test Vehicle Configurations

Each of the primary test vehicles, AFSN's 60-372, 60-375, and 61-327, was instrumented as required for the type of testing performed and the instrumentation recording devices were located in the forward and aft rest areas. Other than modifications for instrumentation· the test vehicles were configured as follows:

. (a) AFSN 60-372. This airplane incorporated all primary A/RIA modifications and was representative of the final configu­ration.

(b)

(c)

(d)

AFSN 60-375. All major modifications were incorporated except the installation of the PMEE, which was simulated by ballast installed throughout the cabin area. Externally this airplane was representative of the A/RIA configuration.

AFSN 61-327. Externally this airplane was representative of the A/RIA plus A-LOTS configuration. Internally, all PMEE and associated equipment were installed except for miscellaneous installations such as carpets, rest area partitions etc. The A-LOTS console was not available, therefore, it was simulated with a ballast installation.

AFSN 61-330. Completely modified to the A/RIA con~iguration. Airplane utilized in the noise level tests.

7

SECTION III

SUMMARY OF FLIGHT TEST RESULTS

The Category I Flight Test results presented herein were obtained in accordance with the procedures set forth in Report DAC 56169, "Category I Flight Test Procedures for A/RIA Systemtl

, dated 12 August 1966 and Supplement No. 1 to Report DAC 56169, "Category I Flight Test Procedures for the A/RIA--A-LOTS Configuration", dated 13 February 1967. For the purpose of this summary report the results are categorized as airplane flying qualities, structural integri ty, performance, modified airplane sub-systems, and PMEE environment. Detailed results of the program 'are contained in Vol. II, Vol. III, and Vol. IV of this report.

During the Category I airplane SUb-systems testing and the Category II testing, Air Force pilots from the using command (AFETR, Patrick AFB) flew the airplanes and reported that the handling qualities were very similar to the basic C-135 airplane which is further substantiated by the flight test data.

3.1 Flying Qualities

The flying qualities of the EC-135N airplane, both in the A/RIA only configuration and in A/RIA plus A-LOTS configuration were very similar to those of the basic C-135A airplane. Tests in which longitudinal, directional and lateral stability characteristics were evaluated, revealed negligible difference from the basic airplane flight characteristics. In general, both modifications tended to move the longitudinal stability neutral points slightly forward, and the A-LOTS pod caused slightly different lateral trim require­ments, otherwise the stability and control was the same as the basic C-135 airplane. Noticeable differences were realized in the airspeed system, stalling characteristics and onset of buffet which are r

discussed below.

Initial results showed that the original location (A/RIA configuration) of the pitot tube was unsatisfactory due to turbulent flow around the nose radome at airspeeds above Mach 0.73. To correct this condition a twelve inch extension was added to the pitottube which resulted in a satisfactory impact source throughout the normal operating flight envelope. The A/RIA nose radome had very little effect on the aircraft static source, however, the addition of the A-LOTS pod had a considerable effect. A com~arison of static position correction curves for the A/RIA onlY and the A-LOTS configu­rations is shown in Figure 7. This shows the difference between the two configurations in that the A-LOTS configuration static position correction varies with change in altitude, whereas the static position correction is the same at all altitudes in the A/RIA only configuration.

8

.06 r--------r--------.-----~_r~------._----~~p--~p--~p~-,--------~ 6.= M-

VM = VM/ y'W/200,000 .04 1--__ -----+--------+--------+--------+---- W . r

-- - A/RIA ONLY (ALL AL TrtuDES) I

--- A/RIA + ALOTS .02

hpm = SEA LEVEL N 10,000 FT

-.04 . r---t--~t---_t±~~-;;-_t___1~:_:::l=::.....-_=+t===::j 21,500 FT

180 220 260 300 340 380 420

Vmw N KNOTS

FIGURE 7. AIRSPEED SYSTEM STATIC CORRECTION COMPARISON

The initial buffet speeds in approach to stalls were within approximately 2 knots of the basic C-135 airplane speeds, however, the addition of the A-LOTS pod causes slightly different handling characteristics in the approach to stall and recovery. With the A-LOTS pod on there is a requirement of right aileron control to counteract the tendency for a left wing down condition as speed is reduced, which in turn causes the right wing to drop at initial buffet, probably due to the spoiler being up on the right wing. Pilot reaction to this right wing down condition then causes the left wing to drop sharply, being more pronoUnced than the wing-drop on the basic A/RIA airplane at initial buffet. This complicates recovery techniques but does not hinder positive recovery if initiated at ~nitial buffet. Therefore, the techniques used in recovery from stalls is the same as for the basic C-135 since the Flight Manual contains a warning that airplane speed should not be reduced to below initial buffet speeds. In addition, it is suggested that lateral control application be monitored during low speed flight with the A-LOTS pod installed as another indicator £or stall warning.

Initial buffet boundaries of the A/RIA and the A/RIA plus A-LOTS configurations were essentially the same, but different than the basic C-135 airplane in the high speed range. At low speed, one "g" initial buffet was encountered at speeds similar to the basic C-135, however, high speed one "gil buffet was encountered approximately .02 to .03 Mach number less than that indicated in the Flight Manual, varying from approximately 0.83M at 40,000 feet to 0.87 M at 25,000 feet. These buffet speeds are well in excess of the recommended cruise speed of 0.75 Mach number. Maneuvering initial buffet was encountered at lower load factors than shown in the Flight Manual.

9

Comparison of initial buffet boundary for the A/RIA with the basic C-135A Flight Manual is shown in Figure 8. Based on these data, at a flight condition of 0.75 Mach and 35,000 feet with an airplane gross weight of 200,000 pounds, maneuvering bu:ffet will occur at 1.5g (480 bank angle).

3.2 Structural Integrity

The structural integrity of the modifications was proven through a limited structural demonstration consisting of normal symmetrical pullout, rolling pullollt and rudder transients, and flutter investiga-· .tions in both configurations; plus trailing wire antenna extension

. and retraction tests, and a nose radome pressure survey in the A/IITA configuration. Flight envelopes· expanded in the A/RIA only, A/RIA pLus A-LOTS, and A/PIA configured with A-LOTS pod removed and Sighting dome and cargo door fairings installed configurations are presented in Figure 9. The maximum flight conditions encountered are shown in the following table:

Configurat i on

A/RIA

A/RIA plus A-LOTS

Ve (Alt)

411 KEAS (19,000)

365 KEAS (21,555)

M (Alt)

0.94 (33,700)

0.93 (32,200)

~.

2.6g

2~6g

The strUctural integrity of the modifications was proven to be adequate to the design speed li~its in the case of the A/RIA only and to the limits established in the C-135AFlight Manual in the case of the A-LOTS airplane due to the placard on the A-LOTS pod. No unusual characteristics were encountered during the structural demonstration so that the basic C-135 airframe was not exposed to any more severe environment than prev:i,ous1.y' tested by the Boeing Company.

The flutter investigations were conducted at three different fuel configurations representing the conditions that couLd be encountered through normal fuel management. Al ti tudes were investigated to include the altitudes for maxinrum "q", maximum Mach number, and combination high "q" and Mach number. Aero-elastic control pulses and oscillations were utilized to excite the airplane bending modes. Accelerometers mounted at surface extremetiesand in various locations throughout the airplane sensed the response to thes'e pulses. The results of the flutter investigation showed that the airplane, in both configurations, is free of flutter to the limits of the flight envelope investigated in all fuel configurations tested. DUring· the flutter investigation on the A/RIA a~rplane a low damped vertical fin oscillation was experienced at approximately 350 knots (KIAS). This oscillation occurred during' aileron and elevator pulses when the rudder was in a zero load condition.

10

MANEUVERING FLIGHT

1.0

1"-- .... '"'-................ -I-- ____

~---~ ....

'" ~ " ~"',

--- FROM T.O. 1C-135A-1 \ \ I I A/RIA & A/RIA + A LOTS 1\\ (IGW ==== 190,000 LBS)

\\ -

I-z w 0.8 U LL LL W 0 U w u

0.6 0: 0 LL ...J « :2 0: 0 Z I 0.4 z

u

0.2

ONE-G FLIGHT

50 .. /' '\ ,

" ", , M I 0

>< l-LL

I

Co .s::

W Cl :::> I-i= ...J

20 «

10~--------~--------~--------~------~~------~---------J ~4 ~5 ~6 ~7 ~8 ~9 \0

MACH NUMBER

FIGURE 8. INITIAL BUFFET BOUNDARY

11

C"l

b X l-ll..

I

a. .J::

w' CI

.:::> I-i= -J « w 0: :::> (j) (j) w 0: a..

CONFIGURATION 1. 5Q , ,

100 200

~ " ~.

~ /

I " 300

Q,' tff: ~1

30 ClJI r:r: " .::f.,'

J.." $:

20 -.J'

§! S'

500 Cl', i.JJ' , ,

10 I , , , , 600 , , , , / , 00

., 0.8 1.0

MACH NUMBER ~ M

CONFIGURATION 2 50r-----,----.-....-----.---r--?T--.

401----+---.

Oa--_-U.<"""""""'""""""'"LL"-OIL-...L-_--'"'-'-_"---J o 0.2 0.4 0.6 1.0

MACH NUMBER ~ M

X l­ll..

I

NOTE 1: SHADED AREAS DENOTE ENVELOPE INVESTIGATED DURING CAT. I AERO-STRUCTURAL FLIGHT TEST PROGRAM.

CONFIGURATION

1. A/RIA ONLY.

2. A/RIA + A-LOTS

3. A/RIAWITH A-LO'TSPODREMOVED-OBSERVATION DOME FAIRING AND CARGO DOOR HINGE FAIRINGS INSTALLED.

CONFIGURATION 3 50~~-r---T7----'----r-rr-~

'401----+--

.:co. 30~~-+-~--W~~~~~~~

MACH NUMBER ~ M

FIGURE 9. FLIGHT ENVELOPES

12

. .

Further investigation and contact with the Boeing Company resulted in the conclusion that this phenomenon was caused by an out of tolerance rudder balance panel condition (slop), and was the same type of vibration which Boeing had investigated on a commercial model of this type of airplane. The balance panel was adjusted to within tolerances and tests were repeated. The oscillations continued to occur although at a smaller amplitude and it was discovered that in most cases the oscillations could be eliminated by trimming so that a slight amount of rudder force was required. This oscillation did not occur on the A-LOTS aircraft although several attempts were made to excite it. This phenomenon is peculiar to the basic C-135 type aircraft and is not a result of the A/RIA modification.

Extensions and retractions of the trailing wire antenna were performed to prove its structural integrity, show adequate stability, and verify proper electro-mechanical operation. Several problem areas were encountered during these tests which resulted in loss of the drogue. The drogue separated from the antenna wire eight times on three different A/RIA airplanes, of which five occurred during flight and three dropped off on the ground between flights. The causes of the failures were primarily due to overload on the wire during drogue nesting, excessive oscillations on extenSion, and poor drogue attach fittings. Eleven different configurations were flown during TWA development conSisting of different types of drogue attach fittings, different size and strength antenna wires, modifications to the drogue nest, addition of a protective spring for the wire and changes in the mechanical and electrical operation of the antenna wire. This development resulted in a trailing wire antenna system that was structurally sound and operationally adequate. The final trailing wire antenna configuration has been successfUlly operated on 10 flights.

The pressure on the nose radome was measured during various maneuvers throughout the test program on AFSN 60-375 to verify that the design strength was adequate. The design limit pressure differentials on the radome were positive 3.98 PSID and negative 5.62 PSID. The maximum differential pressures were experienced during a high speed dive at a Mach number of 0.895 (Ve = 410 knots, hp = 18,940 feet). The maximum positive A P of 3.8 PSID was measured at the nose and the maximum negative pressure of A P = 5.0) PSID was measured along the radome side approximately 1/3 the radome length of the nose.

3.3 Performance

Limited performance testing was performed in both the A/RIA and A/RIA plus A-LOTS configurations to substantiate changes to the C-135A Flight Manual(T .0. lC-135A-l-l) .for use with the EC-135N. Takeoff, climb, and cruise performance were evaluated with the

13

greatest emphasis being put on the cruise performance. Takeoff speeds and ground distances in both configurations were determined to be essentially the same as those published in the C:135A Flight Manual. Climb .data indicated that rate of climb using the Handbook climb schedule was approximately 100 feet/min less than the basic C-135A. The effects of the additional drag related to the A/RIA and A/RIA plus A-LOTS configurations was most noticeable in specific range and specific endurance comparisons. Tabulated below are the configurations evaluated with the respective percent degradation in range factor and endurance noted (based on T.O. lC-135A-l-l performance Charts).

% RANGE FACTOR % ENDURANCE CONFIGURATION DECREASE DECREASE

(a) A/RIA 5.8 6.3

(b) A/RIA with dome and cargo 8',2 8.0 door fairings

(c) A/RIA with unfaired dome 10.9 10.0 and cargo door fairings

Cd) A/RIA plus A-LOTS 14.2 11.5

The optimum cruise conditions for all configurations evaluated were at a weight pressure ratio (W/8 ) between 900,000 and 1,000,000 pounds at 0.75 true Mach number.

3.4 Modified Airplane Subsystems

Evaluation of the aircraft subsystems is based partially on qualitative analysis of performance throughout the Category II Flight Tests, and partly on quanti tati vedata collected during specific. subsystem tests. The navigation subsystems listed below were evaluated to show that there is no degradation in system performance from that shown in T.O. 1C-135A-l Flight Manual due to the relocation of antennas.

SCR-718 Radio Altimeter System AN/ARN-21C UHF Navigation System No. 2 (TACAN) AN/ARN-67 Glide Slope System AN/APN-59 Search Radar

The electrical subsystem changes which included the addition of a 40 r;:{A brush1ess generator and the replacement of the three existing generators with brushless types were evaluated to show that system was capable of supplying power to the aircraft and the PMEE. The lighting, oxygen, and alarm subsystems were evaluated throughout the test program and were shown to be adequate.

14

The relocation of the antennas did not affect the operational performance of the navigational subsystems except in the Search Radar System. The Search Radar operation has been compromised by the A/RIA VHF/UHF tracking antenna, in that the radar can be operated only when the antenna dish is in the stowed position. With this exception, all navigation subsystems function as they do on the basic C-135A aircraft.

Generator performance under various conditions of loading, ground operations, aircraft operations, and PMEE utilization was evaluated including paralleling operation and simulated failure of up to three generators. The results of this evaluation indicated that the electrical subsystems as modified for the A/RIA system is capable of fully supporting the PMEE and is compatible with the other aircraft subsystems. It was also determined that two generators would adequately accomodate the normal aircraft and PMEE electrical loads.

3.5 PMEE Environment

The cabin environment as related to the PMEE and PMEE operators was evaluated in order to determine that the surroundings were compatible for the PMEE operation. The environment measured consisted of that acting on the PMEE, such as cooling and vibration, and that affecting the PMEE operators' performance, such as air­conditioning and acoustics.

The air-conditioning system was demonstrated adequate for cooling the PMEE cabinets, on both the closed and open systems, and is capable of maintaining an average compartment temperature of 70oF, within the operation limits of +20oC to -40oc outside ram air temperature. Figure 10 presents an illustration of temperature variation in the cabin with the PMEE on at a representative missi~n flight condition. The recommended flight condition limits of PMEE operation are defined in terms of the outside ram air temperature as: Upper limit of +20oC, above which an over-heat condition may arise in the PMEE closed cooling system; and lower limit of _40oc, below which the closed system supply air temperature falls below

+32oF.

Vibration levels of several selected PMEE components were measured and determined to be within specification limits. In general, vibration levels were 1.0 grms or less at all flight conditions evaluated except takeoffs (TRT), when levels greater than 1.0 grms were measured at various mounting structures. The measured levels were within design limits of the PMEE.

Modifications to the airplane nose area necessitated relocation of the static pressure reference ports for cabin pressurization.

15

80

TEMP - of 70

!! G") c:: :Xl m .... p (") o s: ~ :Xl -I s: m 2 -I -I

~ 'tI m :Xl » -I c:: :Xl m 52 ~ :Xl tn c:: -I (5 2

60

HEAD LEVEL

FLIGHT CONDITIONS

ALT. - 35,000 FT. AFTER 5 HOURS

RAT

FOOT LEVEL

I 800

I I I

NO.1 - MISSION CO·ORDINATOR NO.2 - AECORD CONTROL @l STA 1008 NO.3 - ANTENNA CONTROL @I STA 772 NO.4 - TELEMETRY CONTROL @ STA 596 NO.5 - VOICE CONTROL @ STA 646 NO.6 - H,F. CONTROL @ STA 825

FWQREST --1 AREA -I.~---------?MEE AREA -------------l----AFT RE!?T AREA .

A-LOTS SIGHTING TURRET

TRAILING WIRE ANT.

Development o~ a satis~actory re~erence source was accomplished by installing the ports on a spherical segment. With this ~ix cabin pressure characteristics were satis~actory throughout the ~light envelope, ~alling within the cabin pressurization performance chart of T.O. lC-135A-l.

The acoustical noise levels were measured throughout the cabin area and were found to be within the limits specified in MIL-A-8806 (ASG) at all PMEE operator positions, although they were higher than predicted. The sound pressure levels in the PMEE operator pOSitions during normal cruise (see Figure 11) ranged between 89 and 96dB (overall), with a speech interference level (SIL) of 73 to 79dB. Sound levels in the range of 73 to 97dB in an o~fice area would be considered noisy to very noisy. This noise is somewhat attenuated by the earphones worn by all EMEE operators.

17

c:: « co 0 c:: ()

~ N 0 0 0 d w c:: (fJ ...J W co (j w Cl I

...J w > W ...J W c:: :J (fJ (fJ w c:: c.. Cl Z :J 0 (fJ

ALTITUDE = 30,000 FT. CABIN ALTITUDE = 5,000 FT AIRSPEED = 285 KIAS MACH NO = 0.75 GROSS WEIGHT = 213,000 LB. PMEE & COOLING SYSTEMS - NORMAL

EQUIPMENT COMPARTMENT 8. 8. CREW POSITION 1 - MISSION CO-ORDINATOR 0- ----0 CREW POSITION 2 - RECORD CONTROL 0-- - -0 CREW POSITION 3 - ANTENNA CONlROL 0··' ....... <) CREW POSITION 4 - TELEMETRY CONTROL 9""--- - 9 CREW POSITION 5 - VOICE CONTROL &: . Ih CREW POSITION 6 - H.F. CONTROL

110r-~~--~~-----'----~-r------~----~-------r------~------~----~

100

A/RIA LIMIT SOUND PRESSURE LEVEL

80

70

60

50

40~~------~----~------~------~----~~----~------~------~-----...l ...J ...J « c:: w > o

45 90

90 180

180 355

355 710

710 1400

1400 2800

OCTAVE BAND - CYCLES PER SECOND

2800 5600

5600 11200

FIGURE 11. CRUISE FLIGHT SOUND PRESSURE LEVELS, EQUIPMENT COMPARTMENT

18

...J

Cii

SECTION IV

CONCLUSIONS

The results of the Flight Test evaluation show that the EC-135N, both in the A/RIA only configuration and the A/RIA plus A-LOTS configuration, can support the PMEE mission without additional flight restrictions, within the basic C-135A Flight Manual limits. The only significant difference realized from the modifications was a degradation in performance due to increased drag of the different configurations.

19

UNCLASSIFIED Security Classification

DOCUMENT CONTROL DATA· R&D (Security classification 01 title. body of abstract and indexing annotation must be entered when the overall report is classified)

1. ORIGINA TIN G ACTIvITY (Corporate author) 2a. REPORT SECURITY C L.ASSIFICATION

Douglas Aircraft Modification Division Unclassified 2000 N. Memorial Drive 2b. GROUP

Tulsa, Oklahoma 74115 N/A 3. REPORT TITLE

A/RIA CATEGORY I FLIGHT TEST FINAL REPORT SUMMARY

4. DESCRIPTIVE NOTES (Typa 01 report anet inclusive etates)

None 5. AUTHOR(S) (Last nBllle, Ilrst name, Initial)

Flight Development, Douglas Aircraft Company

6. REPO RT DATE 7a· 1'OTAI.. NO. OF PAGES j7b. NO. 0; REFS

November 1967 19 841. CONTRACT OR GRANT NO. 9a. ORIGINATOR'S REPORT NUMBER(S)

AF 19(628)-4888 ESD-TR-67-293-Vol. I b. PROJECT NO.

c. 9 b. OTI-1 ER RfPORT "10(5) (Any other numbers that may be s8lligneet this report

d. None 10. AVAILABILITY/LIMITATION NOTICES

DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

11. SUPPL EMgNTARY NOTES 12. SPONSORING MILITARY ACTIVITY

Aerospace Instrumentation Progr~ Office Electronic Systems Division, AFSC, USAF L. G. Hanscom Field, Bedford, Mass. 01730

13. ABSTRACT

This report summarizes the results of the A/RIA. Category I Flight Test Program as reported under separate volumes (II, III, and IV) of ESD-TR-67-293o The major portion of the flight tests were accomplished with three Apollo/Range Instrumented Aircraft (A/RIA) which are modified C-135A airplanes now deSignated as EC-135N's. The test program encompassed aero-structural demonstrations of the A/RIA and A/RIA plus A-LOTS (Airborne Lightweight Optics Tracking System) configurations, plus evaluation of the basic C-135A subsystems which required modifications to support EC-135N Prime Mission Electronics Equipment (PMEE) • Test results demonstrated that: (1) The EC-135N modification was structurally sound; (2) Flying qualities of the EC-135N with and without the A-LOTS pod were comparable to the basic airplane; (3) Degradation in specific range due to the A/RIA configuration was 5.8% and 14.2% in the A/RIA plus A-LOTS configuration; (4) The modified navigation and communication subsystems operated satisfactorily; and (5) The environmental control subsystems were adequate over the normal mission flight conditions. These test results verified that the C-135A as modified (EC-135N) can safely fulfill mission flight requirements and support the PMEE o

DO FORM 1 JAN 64 1473 UNCLASSIFIED

Security Classification sri

UNCLASSIFIED Security Classification

14. LI"lK A LINK 8 LINK C KEY WORDS

ROLE WT ROL.E WT ROL.E WT

A/RIA (Apollo/Range Instrumented Aircraft)

A-LOTS (Airborne Lightweight Optics Tracking System)

EC-135N Flight Test

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UNCLASSIFIED Security Classification