NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0201-20-2301

0201-20-2327 I)?]?

Development, Testing, and Evaluation of

Visual Landing Aids

Consolidated Progress Report

to the

Airborne Equipment Division

Bureau of Aeronautics

Department of the Navy

For the Period

April 1 to June 30, 1955

for

Bureau of Aeronautics Projects

TED No. NBS-AE-10002

TED No. NBS-AE-10006

TED No. NBS-AE-10008

TED No. NBS-AE-10011

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, n

unless permission

25, D. C. Such pe

cal iy prepared if

Approved for public release by the

director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

in part, is prohibited

tandards, Washington

:port has been specifieport for its own use,

Development, Testing, and Evaluation of

Visual Landing Aids

April 1 to June 30, 1955

Report No . 21P-8/55

ZIP-9/55

2588

(Revised)

3606

U072

I. REPORTS ISSUED

Title

Electric and Photometric Tests of a Model Datum

Light for Mirror Landing Systems

Photometric Tests of One Solar Spotlight

Instruction Book for Transmis someter Set AN/GMQ-10

(Revised)

Appendix II to Instruction Book for Transmissometer

Set AN/GM2-10

Development, Testing, and Evaluation of Visual Landing

Aids, Consolidated Progress Report for the Period

January 1 to March 31, 1955

II. TED NO. NBS-AE-10002 • GENERAL RESEARCH, LABORATORY AND CONSULTATION SERVICES IN CONNECTION WITH SPECIALIZED LIGHTING PROBLEMS,

VISIBILITY AND FOG MODIFICATION

a. Visibility Meters and Slant Visibility

Transmis someters : Appendix II to Instruction Book far Transmissometer Set AN/GM3-10 has been couple ted and released as NBS Report 3606.

This appendix consists of the maintenance parts list and a brief description of the function of the parts.

The reproduction of the revised Instruction Book for Transmissometer

Set AN/GMJ-10 has been completed and the manual released as NBS Report

2$88 (Revised)* The revised instruction book includes Appendix II

(described above) and a number of revisions to include the changes in

circuitry and procedure made since the original manual was prepared.

Forty copies of the revised manual have been supplied the Aerology Division.

A list of pen and ink changes and change sheets to be used in modifying the

original manual to include these changes is being prepared.

Efforts are being made to obtain more suitable phototubes and w trigger

tubes”. A visit was made to the plant of the Continental ELectric Company

and the phototube problem was discussed. Experimental phototubes with much

lower than usual dirk current were obtained for test.
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Tests are being made of the deviations from linearity of the photocells used in the 100$-Setting Calibrator* Since these deviations are

apparently unavoidable, a calibration procedure which will correct far

them is being devised.

Brightness Meters ; The construction of two sets of photoelectric

brightness meters and illuminometers has been completed and the units are

ready for calibration and testing* These units win be sent to the Field

Laboratory at Areata where they will be used in the study of the variations

in contrast of runways and runway markings and of the ground/sky brightness

ratio with such parameters as solar elevation, type of cloud cover, visibility, and location* These factors have a significant effect on the visual

range of objects seen against terrestrial backgrounds*

e. General Laboratory and Consultive Services

Marking of Tall Towers g Meetings of the ACC/AGA Subcommittee were

attended and technical aspects of the findings of the Ad Hoc Group studying the marking of tall towers were presented*

Cable Test Detecting Set s The cable test detecting set has been

demonstrated to interested representatives of a number of agencies* It

is now on loan to the Power and Lighting Section of the Civil Aeronautics

Administration* When their tests are completed, the set will be forwarded

to the Areata Field Laboratory for field testing*

Mirror Landing Aids Systems Construction of a unit to demonstrate

several proposed wave-off signals was completed* The unit was used at NAS,

Atlantic City, to determine the desired wave-off pattern and the desired

frequency of flashing the wave-off lights* Tests made at this Bureau indicate that a flash frequency of 75 to 100 flashes per minute is feasible

when PAR 399 approach-light lamps are used* The design of the wave-off

system has been developed and the equipment required for two installations

has been ordered*

Intensity distribution measurements of datum and guide light units

used in the mirror landing aids system tests at NAS, Atlantic City, have

been made and reported* (NBS Reports 21P-8/55 and 21P-9/55)*

Miscellaneous s Intensity distribution measurements of a Doane

high intensity deck-surface light have been made to determine the suitability of the light for use on refueling lanes and the results analyzed*

A report is being prepared*

* Approach-Light System Design s Furnishing technical advice and

assistance to members of the Visual Landing Aids Branch in developing the

control circuitry for the experimental approach-light system at NAS,

Atlantic City, has continued*
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Vo TED NO. NBS-AE-10011. FIELD SERVICE OPERATIONS

ao Airfield Lighting

Approach Beacons g A "stab” approach beacon system consisting of

one approach beacon mounted 500 to 1000 feet from the threshold and a

special threshold lighting system was designed for use in locations where

it is not feasible to mount approach beacons at distances of 1000 and 2000

feet from the threshold,. It was planned to install this stub system on

runway 13® Here* because of the bluff* the approach beacon cannot be

located more than $00 feet from the threshold unless a tall tower is used

to support it© The presence of the ILS antenna shelter is a complicating

factor© Since the lights of the beacon win conceal the obstruction lights

of this shelter* it would be necessary to mount the approach beacon so that

it is as high as the antenna shelter. Tests indicate that in this position

the interference with the localizer signal is too great. Increasing the

distance between the localizer antenna and the approach beacon would

eliminate the difficulty but would require a 15>0-foot tower for the

approach beacon© Other possible solutions to the difficulty are being

considered©

c© Research on Visibility Measurements and Visibility

Transmis sometryg Special phototubes with very low dark current

have been installed in the transmissometers used in the investigation of

the errors in transmission measurements produced by light from the beam

of the projector scattered by the fog into the receiver© This has made

a marked improvement in the test conditions© Preliminary results indicate that when the transmission over the £00-foot base line is about

0.01, the error produced by this scattered light is approximately

(0.0005)o The error produced- by this error in the indicated visual range

is negligible, less than 10 feet.

Slant Visibility Meter s The field units of the slant visibility

meter have been received &om Washington, installed, and placed in operation. In making the installation, 2000 feet of 19-eonduetor #11* directburial cable was removed from the old FIDO system and relaid as part of

the slant visibility meter system. There have been a few minor operational problems including faulty action of control r elays, resulting from

voltages induced into the control lines and a defective reversing switch

in the scan-drive motor© The sensitivity, stability, and signal-to-noise

ratio are more than adequate.

Equivalent Intensity of Flashing Light Units g Reports giving

the results of the effective intensity measurements of flashing lights

and composite units are now nearly complete©
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d„ Electrical Engineering

Airfield Lighting Maintenance Manual s Re Asians of the step-bystep trouble-shooting procedure for series lighting circuits have been

coxnpletedo The trouble-shooting chart which will accompany the procedure

is being revised so that it will be consistent with the revised procedure*

A section covering general information on trouble shooting is considered

necessary0 This section will include explanations which are too long for

inclusion in the step-by-step section* It is in the rough draft stage*

GENERAL

Mr* George E0 Davis * Jr G5 Laboratory General Mechanic (electrical)

GS-7* is now working on a fill- time basis* The change became effective

June 27$ 1955 ° His previous tour of duty was 32 hours per week*

Mr* Robert G* Smith,, Physicist* GS-7* resigned June 3§ 1955 to

accept a position in private industry*

There were only a few low-visibility periods during this quarter*

These were used for measurements of the stray-light error in transmissometers* of the effective intensity of approach beacons^ and in studies

of thresholds*
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