pne 1119 pre-gondola 2

8/8/2019 pne 1119 Pre-Gondola 2

http://slidepdf.com/reader/full/pne-1119-pre-gondola-2 1/56

piqE - 1119

AV

KA

~k f~tc\x~Ib~ c iv l , ,ndusirial and scientific uses for nuclear explosives

UN ITED STATES, ARMY CORPS OF ENGINEERS

iORT PECK RESERVOIR PROJECTMONTANA

PRE,,GONDOLAKPre-Gondola 0

AIRBORNE LIDAR OBSERVATIONSReproduced by

NATIONAL TECHNICALINFORMATION SERVICED D CSonnqlueld. Va 221l1rir

R. T. H. Collis, John Oblanas ~

(V ;1 tanford Research Institute 2 9*~ ~. Acrophysics Laboratory

Menlo Park, California

U. S. Army Engineer Nuc-lear Crotering Group ISSUED: January 1968Livermore, Colifornia



PN E 1119FINAL REPORT

PROJECT PR.E-GONDOLA II

AIRBORNE LIDAR OBSERVATIONS

R. T. H. CollisJohn Oblanas

Stanford Research Insti tuteAe rophys ic s Labora toryMenlo Park , California

November 1967



,LEGAL NOTICEThis report was prepared as an account of Government sponsored work. Neither the UnihidStates, nor the Commission, nor any perso acting on behalf of the Commission:

A. Makes any warranty or rnpresetation. expressed or implied. with respect Io doe aces-racy, completeness. or usefulness of the Inormantion contained In this report, or tha the weof any information, apparatus, method, or process disclosed to this report may not Infringsprivately owned rights; or

8. Assume* any liabilities with respect to the use of, or for damages resumlting from douse of any information. apparatus, method. or process disclosed In this report.

An used in the above. "person acting on behalf of the Cosaalselem" lAcludes sey s--ploys@or coatractor of the Commission. or emploegs of such eeatraoe, to ths sadeft thesuch employsie or sostactor of the Commission, or employee of such oesatraeWi prepares,disseminatse&. or prnvides access to, any Islematiem parsuantoh his em#tagmnti er enWith the COWAm$iseSa,Or his efhleyNme With such 111011110e

'tin~* WiI~TECT4NiSB.C SWIF ECTION

RIST. AVAIL dtK WEIIAL'

Printed in the United States of AmericaAvailable from

Clearinghoruse for Federal Scientific and Technical InformationNational Bureau of Standards, U. S. Department of Coinerce

Springfield, Virginia 22151



-3 -"i" UlXt

A < 4I '

V.

'4)

'C

'-4

C

NO T REPROOUCIBLE



AA



ABSTRACT

Lidar ( laser radar) observations from an ai rcraf t of the cloud of debris

result ing from the Pre-GONDOLA II explosion at F o r t Peck , Montana, are

described. With the neodymium (near infrared) lidar pointing horizontally

a t 450 af t of the ai rcraf t beam, th e ai rcraf t made a ser ies of flights past

the cloud position at a height of approximately 225 mete r s above ground

level and the lidar was fired at intervals of approximately 6 seconds. Since

the cloud rapidly became invisible, these flights were positioned withreference to the l idar observations using a Doppler navigation sys tem. From

the l idar observations the location, shape, an d internal s t ruc ture (in t e rms

of variations of density) of the cloud at the flight level were determined at

five success ive times, extending some 37 minutes after the explosion and

some 17 kilometers downwind. While this technique is thus shown to be

immediately available (with minor improvements) fo r l imited operational

application, the developments necessary to realize it s full potential are

identified an d described. In particular, significant improvements in the

data handling system are proposed.

111



ACKNOWLEDGM ENT

We particularly wish to acknowledge the very willing cooperation

received from Edgerton, Gerrneshausen and Grier, Inc., both in prepar ing

the ai rcraf t fo r the experiment and in carrying out the flying experiments,

especially in view of the fact that M r. F. Thompson and hi s crew came

straight to this project from a period of extended flying.

We also wish to acknowledge the assistance and collaboration of

M r. N. Sykos of Lawrence Radiation Laboratory, who acted as Safety

Officer.

lv



CONTENTS

ABSTRACT . . . . . . . . . . iii

ACKNOWLEDGMENT. . . . . . . . . iv

I. INTRODUCTION 1

A. Description of Pre-GONDOLA II . . . . I

B. Objective . . . . . . . . 3

C. Background .. . . 3

II. PROCEDURE. . . . . . . . . 4

A. Operational Plan . . . . . . . . 4B. Laser Safety . . . . . . . . 6

C. Description of the Experimental Equipment . 7

III. RESULTS . 14

A. Program Summary . . 14

B. Data Summary . . . . . . . . 17

IV. ANALYSIS, DISCUSSION, AND INTERPRETATION 18

A. General Remarks . . 18

B. Cloud Posit ion and Shape . 19

C. Cloud Displacement an d Wind Velocity . 19

D. Cloud Density. I . . . . . . 22

E. Cloud Volume . . . . . . . . 22

V. CONCLUSIONS . . . . . . . . Z7

VI. RECOMMENDATIONS . . . . . . . 29

A. Operational Technique. Z.

B. Lidar Equipment . . . . . . . . 30

C. Data Process ing System 31

v



VI. RECOMMENDATIONS (Cont)

D. Navigat ion . . . . . . . 37

E. C o m m u n i c a t i o n s . . . . . 39

REFERENCES . . . . . . . . . 41

APPENDIX . . . . . . . . . 42

TABLES

I. Mark V Neodymium Lidar Charac ter i s t ics 10

II. Data S u m m a r y. . . . . . . . . 17

FIGURES

1. Site of Project Pre-GONDOLA II .

2. Successive Ground Tracks of the AircraftDur ing E x p e r i m e n t . . . .

3. Mark V Lidar Optical Diagram . . . . 9

4. Plan View of Scanning Scheme - Airborne Lidar 11

5. Block Diagram of the Mark V Lidar Electronics 12

6. Successive Locations of the Cloud . . 20

7. Cloud Displacement Along Mean Path - 1480 T. z.

8. Relative Density Variations of the Sub-visible Cloud,

Run 3, 6.8 Km From GZ in DB Above Background. Z39. Relative Density Variations of the Sub-visible Cloud,

Run 14 , 11 . 5 Km From GZ in DB Above Background ?4

10. Relative Density Variation of the Sub-visible Cloud,Run 5, 12. 8 Km From GZ in DB Above Background 25

11. Relative Density Variation of th e Sub-visible Cloud,Run 6, 15.6 Km from GZ in DB Above Background 76

12. Proposed Second-generat ion Data Process ingSystem . . . . . . . . . 36

vi



I INTRODUCTION

A. Descript ion of Projec t Pre-GONDOLA II

Pro jec t Pre-GONDOLA II wa s a row-charge cra te r ing experiment in

weak, w et clay-shale conducted by the U. S. Army Engineer Nuclear

Cratering Group (NCG) as a par t of the joint Atomic Energy Commiss ion /

Corpq of Engineers nuclear excavation research program. Th e pr imary

purpose of this nominal 140-ton 5-charge row-charge experiment was to

gain row-charge cratering experience in a weak, w et medium. In addition,

this experiment tested techniques fo r connecting a row-charge crater to an

existing cra ter and fo r over-excavating to accept throwout from a follow-on

connecting row-charge cra ter.

Pro jec t Pre-GONDOLA II wa s detonated ýLtValley County, near the

edge of the F o r t Peck Reservoi r approximately 18 miles south of Glasgow,

Montana, at exactly 0800 hours (MDT), 28 June 1967 (see Fig. 1). Coor'li-

natesof the center charge were W106 0 38' 31", N47 0 55' 51". The orientat ion

of the row was along a 110 Eas t of North to 11°0 West of South al inemnnt ex-

tending through' the center of Charl ie Crater.

Th e average lip cres t to li p c r e s t dimensions after connection to the

Charl ie Crater were 640 ft x 280 ft. Individual charge yields, depth,

spacing, and result ing apparent cra ter dimensions were as follows:

I



Missouri R.

Glasgow MONTANA

4"'.~

' Sp.illwa

)I ~Fort Peck Dom

0, buIck Creek Inlet

/ '• •Pre-Gondola "

Pirtes Pecre wicn Cm

) Airport Paved Road Scale in Miles

4+ Landing Strip ....- Graded Road 0

FIG I CITE OF PROJECT PRE-GONDOLA 3r

2



II PROCEPURE

A. Operational Plan

The operat ional plan, which had been rehearsed riurin, the test fli:,.ht

of 27 June, called fo r the initial posi t ioning of the NATC ai rcraf t to the

southwest of ground zero. From this position, the ai rcraf t could becin

the f i rs t ru n pas t the cloud immediately after the ao-ahead wa s received

from the test director.

Th e th ree-man SR I crew aboard the ai rcraf t were emplo 'ed in the

following way. An observer st-Lioned at the l idar sightinc telescope con-

t rolled the firing of the lidaro He commanded a view of the entire region

surrounding the aiming point of the l idar. The l idar re turn signal was dis-

played on a Tektronix oscil loscope upon which w as mounted a recordin, .

c a m e r a . Th e second observer photographed each return signal on Polaroid

film, and also monitored the per formance of the l idar apparatus. The third

observer w as stationed at an auxil iary oscil loscope, and visually monitored

each l idar return fo r the presence or absence of a return signal from the

cloud. In addition, the Lawrence Radiat ion Laboratory l aser safety coordin-

a to r w as l oca t ed ad jacen t to th e l i da r siL,!htinu" s t a t ion , an d cou ld e l e c t r i c a i l

inhibit the firing of the l idar at any tiim;e he deemed necessarv.

After the detonation, the aircraft w as flown on a ser ies of courses,

t ha t had been p l anned prev ious ly with rc.rd 'm,dind d i rec t ion an d velc

(See Fig. 2). The l idar commenced firinf, well ahead of the estimated

position of the cloud, and continued firinu ,nlil no further cloud re turns were

received on each run.

T h e intent ion w as to use th e aircraft's Flopp . r n a v i g a t i n sys ten to



N 2Z

o I 10STAiLTE MILES

FIG 2 SUCCESSIVEGROUNDTRACKS OF THE AIRCRAFT DURING THE EXPERIMENT

6



provide a f rame-work of reference for making the observations and for

providing ass is tance to the pilot to maintain accurate courses during the

observa t ions . Thus, the Doppler plot was started on a recognizable land-

m a r k (the Doppler Point) an d oriented so that it s track was parallel to the

expected downwind path of the debris cloud and sufficiently to one side to

allow the l idar observations to be made . Each ser ies of l idar observa t ions

w e r e to be started a t a point along this track, which w as called the Lidar

Point fo r the ru n in question. In this way, it w as hoped that a substantial

pa r t of the program could be carr ied ou t without changing the ke y Doppler

Point . F or each pass a new Lidar Poin t would be selected along the

Doppler track in accordance with the experience of the cloud motion, to

indicate a t what t ime th e l idar shots should begin.

The advantages of this system were that the pilot could position his

ai rcraf t at the s tar t of the ru n on good l andmarks . He could then fly the

"selected t racks with the aid of the Doppler system by maintaining a course

that yielded zero drift indications on th e Doppler indicator. The Doppler

indications of distance along th e track then provided an indication of when

th e l idar observa t ions should begin.

Since it was intended to make observa t ions on both downwind and upwind

passes , an identical Doppler positioning scheme was planned fo r the re turn

upwind p a s s e s .

To provide running checks of the Doppler e r ro r each Doppler ru n wa s

to be closed on an identifiable l andmark . Cince the data record ing sys tem

ha d provision for mark ing an y desired "event" (including l idar fir ings, and

recording the coincident Doppler plot position), it w as hoped that t 'ubsequent

analysis would cnable a ll l idar f ir ings to be related rigorously to ground

7



posit ions.

At th e termination of each run, photographs of the l idar re turns were

examined and compared with a m ap showing the ground t rack of the ai rcraf t .*

F r o m this information an d from the estimated wind data, the size of the

cloud an d its future position were estimated, and the pre-planned courses

w e r e modified as requi red to properly position the next ru n with respect to

the moving cloud. Repeated runs were made in the manner described above

until contact with the clo ud wa s lost .

B. L a s e r Safety

All l idar observa t ions were made in accordance with the procedures and

safety cr i ter ia outlined in Annex B of the "Technical Director ' s Operations

Plan fo r Pre - GONDOLA II.,

Th e safety plan w as based on visual surveil lance of the volume of space

surrounding the l idar ?ath. This volume w as moni tored by the l idar operator

with the ai d of a sighting telescope whose optical axis w as alined parallel to

the l idar beam. The l idar was not f ired when ai rcraf t were within the field

of view of the sighting telescope, or when the ai rcraf t attitude was such that

the l idar beam could strike the ground. In addition, the safety coordinator

independently scanned th e genera l area around the l idar beam with binoculars

and could inhibit firing of the l idar if he deemed it necessary.

C. Descr ip t ion of the Exper imenta l Equipment

1. Mark V Lidar

Th e Mark V l idar t ransmit te r consisted of a Q-switched, neodymium-

* Th e ground track of the ai rcraf t wa s plotted by th e Edgerton, Germeshausen

and Grier technical crew from data obtained from the Doppler navigationsystem.

8



doped glass laser whose output radiation occurs in the near- inf rared

portion of the spectrum at a wavelength of 1. 064. Th e laser is capable

of producing pulsed coherent radiation of 15 nanoseconds duration, with a

peak power output of 25 Megawatts . Th e laser output bearr divergence

(beamwidth) is approximately 5. 6 mil l i rad ians . Since the angular reso-

lution of the l idar is determined by the transmitted beam divergence,

coll imating optics ar e used to reduce the beam divergence and to produce

an output bearmwidth of 0. 35 mil l i rad ians . Th e corresponding two-dimensional

spatial resolution of this beam is 0. 35 m at the range of I km . Th e range

resolution of the equipment is 2. 3 m. Th e pulse-repeti t ion rate (PRR) of

th e Mark V l idar is pr imar i ly l imited by the ambient air t empera ture ,

which determines the cooling rate of the l a se r head. F o r the t empera ture

encountered during th e observations discussed here , the maximum PR R

that could be attained was approximately 12 pulses per minute.

Th e l idar rece iver consists of a 6-inch diameter Newtonian reflecting

telescope, identical to the t ransmit te r optics. An adjustable field stop at

the focal plane l imits the rece iver acceptance angle to a maximum of 6

milliradians. A multi layered interference fi l ter with a wavelength interval

(bandwidth) of 0. 014 is inserted in the rece iver optical path to reduce the

output noise level produced by solar radiation scattered into the receiver

field of view. The dec tec tor consists of an RCA 7102 photornultiplier with

an S-1 spec t ra l response. An optical diagram of the l idar is shown in

Fig. 3.

A detailed discussion of l idar detection of a tmospher ic t a rge ts and

l idar equipment design features is beyond the scope of the present repor t .

These topics are treated extensively in Refs. 1, 2, and 3.

9



9L w 0

0 I 0-

o6 I 0w~ wi

LaC.

a. Ix i

0 CL I00

w IA.L

w 0

.. ). g.4.z cc

00

0,2

10



Table I summarizes the pertinent charac ter i s t ics of the Mark V l idar.

Th e l idar t ransmit te r and rece iver were located on the por t side of

the ai rcraf t , jus t af t of the existing electronic equipment rack . Th e lidar

was mounted so that it looked horizontally in a direction 45 degrees af t

of the ai rcraf t ' s beam to the left . (In this way, as shown in Fig. 4, the

number of shots traversing the cloud was increased). Th e remaining

units of the l idar were mounted at various locations in the nearby electronic

equipment rack. Three cylinders of compressed nitrogen provided energy

fo r the laser Q-switching turbine. *

2. Electronics and Data Recording Equipment

Th e major electronic components of the l idar and the data record-

ing system are illustrated in block diagram form in Fig. 5. A compressed

ai r-dr iven turbine rotates the laser Q-switching prism at 500 revc•utions

pe r second. Upon receipt of a fire signal, the synchronizing generator

tr iggers the flash lamps in step with a signal from the rotating pr ism. A

capacitor bank charged to approximately 3 kV supplies energy fo r th e laser

flash lamps. A photo diode senses the occur rence of the laser pulse and

produces a t r igger to s tar t the data recording equipment. Th e output of

the photomult ipl ier in the lidar rece iver is fed to a pulse ampl i f ie r having

a logari thmic t ransfer function, and then to two Tektronix 453 oscil loscopes.

A Polaroid recording camera mounted on one oscilloscope facil i tated the

initial alinerr-3nt of the equipment and w as used to photograph the lidar

return signal. An independent backup system consisting of a manually

operated 35-mm recording camera mounted on an auxil iary oscil loscope

Th e electric motor-driven air compressor normally associated with thel idar could no t be used because of pr imary power l imitat ions aboard theai rcraf t .

11



Table I

MARK V NEODYMIUM LIDAR CHARACTERISTICS

Transmi t te r

Lase r Neodymium-doped glass

Wavelength 1. 06ýi

Beamwidth 0 .3 5 Milliradian

Optic s 6-inch f/ 4 Newtonian reflector

Peak P o w e r Output 25 Megawatts

Pulse Length 15 Nanoseconds

Q-switch Rotating prism

Receiver

Optic s 6-inch Newtonian reflector

Field of View 3. 0 Milliradians

Pre-Detec t ion Fi l ter 0.01 (100A)Wavelength Intervel

Detector RCA 7102 Photomultiplier (S-1 cathode)

Post-Detection Fi l ter 28 GHzBandwidth

12



r0*

VI c

W

00

-JL

> z

0L02

LL c

13-



w a. 0

0 04

0 -0

0

w~ 9L

0o 0

0

w w

U 0

0r -aWo

w

0 u 4

C, 0

0

L.4

0

cn CL 0

L)6z -.

Z 14



Ias used. to photograph each t race. A telephone systeni wa s installed to

facil i t i te communicat ion between the three-mnan l idar teanm and the safety

coordinator. An audio tape recorder connected to the telephone line was

used to record various equipment settings, as well as a running con.r.,.entary

on the progress of the experiment. In addition, the observer stationed at

tI'e lidar sighting te lescope had access to the ai rcraf t ' s normal intercn-r.-uni-

cation system.

A 70-mm view camera was instal led near the l idar A photograph was

automatically taken at every firing of the region surrounding the l idar field

of view.

3. Aircraf t Equipment

Data concerning the t ravel of the aircraft over the ground was ob-

tained from the Doppler radar navigation systenm (AN/APN-183) aboard the

aircraft . The instantaneous coordinates* of the aircraft were printed on

paper tape at every firing of the l idar.

Additional navirat ional data were printed in tabular form by a t . le-

t-ype unit as,;ociated with the a i rcraf t digital con-puter ,-torr. The data

(which included altitude, grounaspe-. i , magnetic headinc, drif t angl,, 'virei

speed, and direction) were printed ou t at e--ery firinf, of the l idar.

Refe renced to a r e c t a n g u l a r coord ina t e system that i n c luded a know- .tn.rt-inv and ending point for each run.

15



III RESULTS

A. P r o g r a m Summary

Th e modifications to the NATS ai rcraf t required fo r this exper iment

w e r e accomplished by E. G. and G. at the aircraf t ' s home base .

The m a j o r modifications were :

(1) Construction of a mount fo r the l idar t ransmit te r andrece iver

(2) Construction of viewing ports fo r the l idar at an existing

escape hatch

(3) Provis ion of 110 volt, 60-Hz power

(4) Provis ion of a power distribution panel

(5) Provis ion of mounting ar rangements fo r the othercomponents of the l idar sys tem.

On 7 June, the NATS a i r c r a f t (a Mart in 404) arr ived at San Francisco

International A i r p o r t fo r a t r ia l installat ion of the l idar equipment. Th e

equipment w as installed during the day. On the following morning, the

l idar w as alined an d checked fo r proper operation. A tes t flight in the

local areas w as conducted in the afternoon to verify the proper operation

of the equipment under actual operating conditions. At this t ime, a care-

fu l check w as made to determine if operat ion of the l idar would produce

elec t r ica l t rans ien ts capable of interfering with the proper operation of

other equipment aboard the ai rcraf t . Also, the operation of the l idar wa s

moni tored to verify that operation of the aircraf t ' s electrical and electronic

equipment would no t produce spurious tr iggering of the l idar. A ll equipment

aboard the ai rcraf t per formed properly, and no interference of either kind

w as observed . A number of runs were made past severa l smal l cumulus

clouds to simulate the cloud t racking operation. Th e purpose of these runs

1 6



w as to obtain an appreciat ion of the t ime scale involved in t racking re la-

tively smal l clouds with a fas t moving ai rcraf t . A secondary purpose

w as to obtain l idar data that w as later used to optimize the various sett ings

of the l idar equipment. Th e duration of the test flight w as approximately

2. 5 hours. On 9 June the l idar equipment was removed, and the ai rcraf t

re turned to it s home base .

The original schedule was such that the ai rcraf t would be available at

Glasgow, Montana, fo r severa l days before the shot . A number of test

f l ights ha d been planned during which time the l idar t racking and plotting

technique could be optimized. Because of higher priority commitments of

th e ai rcraf t , it became n e c e s s a r y to delay the instal lat ion of th e l idar until

the morning of 27 June. The SRI crew, with the equipment, m et the air-

c raf t a t Twin Falls, Idaho. - Th e instal lat ion w as comple ted during the

flight from Twin Falls to Glasgow. A tes t flight w as made in the late af te r-

noon of V7 June but w as necessar i ly l imited to checking ou t the equipment

and establishing an ini t ial plan of operat ion of a minimum nature.

All equipment functioned proper ly. The duration of the tes t flight wa s

approximately one hour.

In the actual observational flight on the morning of the 28th, some

difficulties arose in connection with the proper positioning of th e ai rcraf t ;

also, because of insufficient time, it had niot been possible to put the 70-mm

view c a m e r a in effect ive operat ion. A malfunction occurred in the digital

computer that resulted in loss of the data normally printed ou t on the tele-

type unit. Th e main problem w as at the interface between the ai rcraf t

Th e l idar was involved in another project there.

17



crew and the l idar crews. This resulted inevitably from th e from th e lack

of preparation and prac t ice cause- ' bv th e cur ta i lment of the test flight

per iod . Again, shortcomings in the intercommunication bysterr between

th e crews could not be rectif ied in the t ime available. The experimental

method descr ibed in Section II-A was fol lowed, an d th e cloud w as success -

fully observed by l idar during five of th e f i rs t six runs. Contact with the

cloud w as los t af te r ru n si x (approximately 38 minutes after detonation)

and th e remaining four runs failed to re-es tabl i sh contact with the cloud.

Th e l idar equ ipment operated without malfunction during th e entire

flight. Th e duration of the observational flight w as approximately two hours.

A pre l iminary reduction of the data w as accomplished af te r the flight,

and an informal letter r e p o r t describing the exper iment an d th e pre l iminary

resul t s were submitted on the evening of 28 June.

The following day, th e ai rcraf t stopped a t Twin Fal l s on it s re turn

trip, where th e l idar equ ipment w as removed.

An Interim Data Report w as submitted on 24 July 1967.

18



B. Data Summary

TABLE II. S u m m a r y of l idar data obtained in this exper iment

Ptar t Time En d Time Number of Number of Shots

Ru n No. (MDT) (MDT) Shots Fired Travers ing Cloud

1 0804:43 0805:42 7 1

2 0808:35 0809:56 9

3 0812:24 0814:33 9 6

4 0822:15 0826:05 23 6

5 0829:22 0830:16 8 6

6 0835:10 0838:20 24 6

7 0847:00 0850:26 28

8 0856:00 0900:00 21 -

9 0913:00 0916:45 41 -

10 0920:00 0926:00 46

Total 21 6

The prirnar-.ý data for this repor t consisted of the 216 l idar re turns

recorded on Polaroid film along with the ground coord ina tes of th e a i r c r a f t

cor respondina to each l idar shot.

19



IV ANALYSIS, DISCUSSION, AND INTERPRETATION

A. General Remarks

After the detonation, which occur red a t 0800 MDT, th e main ser ies of

runs were made at an altitude of approximately 225 m e t e r s above the t e r r a in

in such a way that on each run, a succession of l idar shots probed a hor i -

zontal plane intersecting the cloud. Each run was intended to provide opti-

m um viewing of the cloud as it w as displaced by the wind. On each run,

the l idar was f ired at regular intervals (a t a rate of approximately 10 per

minute), start ing from a point well ahead of the cloud's es t imated position

an d continuing unti l nc fur ther echoes were recorded .

The ai rcraf t maintained a true a i r speed of approximately 155 knots,

giving a downwind ground speed of 165 knots an d an upwind ground speed

of 145 knots . A t these speeds, l idar shots were made a t approximately 552

m e t e r intervals along the track on downwind runs an d a t intervals of 485

m e t e r s on upwind runs. Diff icult ies were experienced in positioning the

ai rcraf t an d the runs made were badly located with r e s p e c t to the cloud;

in addit ion, the runs were made at overlong intervals in some cases . (It

should be reca l led that the cloud became bare ly perceptible to the ey e

shortly after the detonation and w as quite invisible by about minute 15).

Th e top of the cloud did no t appear to rise above 250 m e t e r s or so

above ground level and rapidly became quite tenuous as it moved a t a

velocity subsequently measured a t 148 degrees (T), 7. 0 m e t e r s per second.

Th e furthest distance of dust detection w as 6. 7 km a t 29 minutes, 55

seconds af te r detonation. At this t ime the cloud was some 13. 8 krn from

ground zero. Th e greatest distance from ground zero at which the cloud

20



w as observed w as 16. 5 km at minute 37.

Extensive searching failed to re-es tabl i sh contact with the cloud after

Run 6 (the last return being obtained at minute 37:36). By this time the

cloud had become very diffuse, bu t it is probable that some further t rack-

ing could have been achieved ha d the ai rcraf t positioning been fully effective.

B. Cloud Posit ion and Shape

Figure 6 shows the successive locations of the cloud as it w as displaced

by the wind. The ai rcraf t t racks are shown, each identified by the ru n num-

ber ; along each t rack the position at which the l idar was f ired is indicated.

(Only signif icant l idar shots a re so indicated) . Th e position of th e lidar

points has been adjusted on the bas is of th e measured wind displacement to

give the optimum representation of th e shape of the cloud a t mid- t ime (cen-

tered on the position indicated with a square) .

Th e orientation of the m a j o r axis of the cloud is in good agreement with

the orientat ion of the Pre -GONDOLA It cra ter, an d does not appear to change

significantly with time. The shape of th e observed port ion of th e cloud does

not change rapidly with time; this charac ter i s t ic agrees fairly well with the

behavior of Pre -GONDOLA I Delta event , where an approximately circular

cloud w as t racked fo r 10 minutes . Meaningful conclusions concerning cloud

size and growth cannot be presented because of th e l imited sampling of

only a portion of the cloud. However, it is interest ing to note that the size

of the observed port ion of the cloud did not appear to increase as rapidly

as the Pre -GONDOLA I Delta Cloud 4 . F o r example, in the t ime interval

between 0814:08 and 0837:23 (see Fig. 6) the cloud size increased by a factor

of 1. 3. During the Pre -GONDOLA I Delta event , in the t ime interval from

three minutes to ten minutes af te r the detonation, the cloud size increased

21



G+ .TOP OF

CLOUO,

0I 01 0." ...

WINDO

O"/"

"302941 M*DT

"- -II ,, [y°\' Y •i, -.9:•"5

082534

//

FIG.6 SUCCESSIVE LOCATIONS OF TH E CLOUD

2z



by a factor of 2. 4.

C. Cloud Displacement an d Wind Velocity

Th e successive locat ions of the cloud along the mean path Fig. 6 ar e

plotted as a function of t ime and shown in Fig. 7. Th e displacement is

seen to be remarkably regular at the height of the observations (approxi-

mately 225 meters above the surface) and cor responds to a wind velocity

of 7 .0 meters per second from 328 degrees (T).

It is also interest ing that th e trajectory of the cloud in Fig. 6 does not

originate at ground zero. This is probably partly due to the uncertainty in

determining the mean path an d the position of the cloud relat ive to the mean

path was anomalous in i ts early stages (due to different wind direct ions at

the lower level), apparent e r roneous motions along the mean path would

resu l t from the plotting procedure employed in Fig. 7.

D. Cloud Density

Contours of relat ive echo intensity fo r Runs 3, 4, 5, and 6 are shown

in Fig. 8, 9, 10 , an d 11 respectively. These contours indicate, on a log-

ari thmic scale, the relat ive density of the debris within the cloud, as wcll

as ca n be inferred from the available data. Various attempts were made

to relate echo intensity, area of the cross sect ion, and t ime along the

lines of the analyses made of the Pre-GONDOLA I data. Th e l imited

nature of the present data, however, did no t permi t meaningful in te rpre t s -

tion to be made. Th e res t r ic ted data rate of the experiment was inappro-

priate f-,r the small scale of the size an d structure of the Pre-GONDOLA II

cloud. The resolution of the data along the l idar path is on the order of100 m e t e r s bu t in the direction of the ai rcraf t ' s motion the resolution falls

to 350 to 400 m e t e r s .

1-;



29

w 0

-J

a. z 1

0 0.

a.a

0

2W



N

0 15

2~J~15LEur

flG.WIN 7ELps

CLOUDR R M c z I aA~



I

/I

/0 N

// WIND 7mps

GROUND II ,

TRACK SCALE- kmn

/

FIG 9 RELATIVE DENSITY VARIATIONS OF THE SUB- VISIBLECLOUD RU N 4 11.5kim FROM GZ IN DB ABOVE BACKGROUND

26



0829:41

AIRCRAFTGROUNDTRACK

N

IWINO iraps /J

10

'5

0 .5

SCALE--km/

II

FIG.AO RELATIVE DENSITY VARIATION OF THE $US-VISIBLECLOUD RUN 5 12.8kim FROMGZ IN DO ABOVE BACKGROUND

27



N

l0

//

15 WIND 7mrs

15 '

AIRCRAFT

TRACK

0837;23

0

SCALE-km

FIG II RELATIVE DENSITY VARIATION OF THE SUB-VISIBLECLOUD RU N 6 15.6km FROM GZ IN DB ABOVE BACKGA,,.';:.

2R



V CONCLUSIONS

It is concluded that the experiment ha s very successfully demonstrated

the potential of airborne l idar fo r tracking clouds of debris even when the

clouds ar e invisible.

Because of the diversion of the aircraft fo r a higher priori ty flight

immediately before this experiment, the preparations fo r the actual obser-

vational program were hurried and limited. Nevertheless, the earl ier

technical preparation and the reliability of the l idar system used were such

that the installation and operat ion of the l idar presented no difficulties and

no malfunctions were experienced.

The observat ional program carried ou t ra n less smoothly than it could

have, due mainly to problems in maintaining an effective running plot of

the operation and positioning the aircraft correctly. These problems were

due to the fact that it ha d not been possible to car ry out the necessary

t raining and development flights that had been planned.

Nevertheless, a very effective series of observations was made of the

cloud, which in any case was no t as large or dense as we ha d anticipated.

It wa s found possible to t rack the cloud long after it had become invisible

to the eye, and to determine i ts internal structure at each successive

location (a t the flight level--viz. , 225 meters above the surface) .

The experience gained has been most valuable and ha s clearly indica-

ted how navigational and direct ional procedures could be improved.

It is considered that even the present laboratory type lidar equipment

could give useful operational information on the location and structure of

a large cloud over extended distances. The extent of this information,

3n



however, would depend signif icantly upon the data-handling ar rangements

used in this tr ial . Var ious possibil i t ies fo r improving this aspec t of the

application are apparent, however, and their adoption should be considered

in t e rms of the operat ional r e q u i r e m e n t and the economics involved.

For ear ly applicat ion of the currently available l idar, no m a j o r changes

appear needed in the instal lat ion ar rangements , although improvements

could readily be made in the area of providing power, particularly fo r the

operat ion of the Q-swi tch .

Ways in. which the subsequent development of improved l idar systems

fo r this purpose should be approached emerge fairly clearly from the ex-

perience gained, an d future p r o g r a m s in this area will benefi t accordingly.

31



VI RECOMMENDATIONS

A. Opera t iona l Techniques

Recommendations regarding improvements in operational techniques

are int imately related to the recommendat ions made regarding equipment

developments and data process ing d iscussed in detai l below. Again, the

very important question of positioning the ai rcraf t fo r making the observa-

tions is discussed in detail separa te ly.

It appears, however, that the basic concept explored in this experi-

m e n t is correc t fo r the type of l idar that has too low a data rate to make

two- or th ree-d imens iona l scanning feasible. With l idars with l imited

data ra tes it seems that the optimum probing techniques, an d one that

accords well with safety practices, is to instal l th e l idar in a fixed posit ion

point ing horizontally, ei ther at r ight angles or incl ined to the ai rcraf t ' s

axis . Scanning at a selected level ca n then be accomplished by flying

pas t the anticipated position of the cloud, and making a ser ies of lidar

shots, start ing well ahead of the cloud and continuing until no further

echoes are detected. This technique requi res that at l eas t a minimal

indication of the l idar return be available to the opera tor immediately

after firing the l idar, and also that an adequate running plot of the opera-

tion be maintained during the course of the observations. Th e lat ter is

of course necessary in any case if any immediate operat ional use is to be

made of the l idar observations.

To acquire data throughout the vertical extent of the cloud it is neces-

sary in this method to make a ser ies of passes at different , -vels. the

type of data acquired by this scanning procedure , if conveniently

32



an d rapidly presented, appears to be very suitable for many operat ional

purposes. With l a rger clouds, the l imitat ions of data rate an d resolution

noticed in probing the Pre -GONDOLA II cloud would be less res t r ic t ive .

In fact , the type of scanning proposed is m o s t effective in the case of

very extended or diffuse clouds.

B. Lidar Equipment

Th e design of an operat ional airborne l idar should no t necessar i ly

be based upon the current M a r k V equipment. The f i rs t step in planning

for an optimum operat ional l idar should include a sys tems analysis study

to accomplish the following:

(1) Define the operat ional requi rements that the prospective

equipment m u s t satisfy.

(2) Define an optimum ar rangement of equipment that will

satisfy the operat ional requirements, within various

prac t ica l cons t ra in t s (such as available t ime an d fund-

ing, the per formance l imits of present and future equip-

ment, and laser safety) .

A study of this nature would yield a number of advantages:

(1) It would provide high performance equipment well suited

to the operat ional requirements at a minimum cos t .

(2) It would provide a unified plan fo r gradually upgrading

the equipment as the future operat ional requi rements

become m o r e severe.

(3) It will resu l t in a smal le r, more compac t system which

could be installed in a smal le r, more maneuverab le

33



ai rcraf t , thus significantly reducing direc t operating

costs.

In shor t , a sys tems study of modes t p ropor t ions could make the

difference between an effective l idar cloud t racking system and one of

margina l usefulness.

A study of this nature is beyond the scope of the present repor t ;

however, because of th e experience gained during th e a i rborne program,

severa l genera l improvements to the l idar ca n be identified:

(1) Lidar Firing Rate. - Although the firing rate of the

Mark V (approximately 10 shots per minute) w as adequate

fo r the present experiment, s ignificantly higher fir ing

rates will be necessary to realize the full potential of

airborne l idar. These higher f ir ing rates ca n be achieved

by the addition of liquid cooling to the laser cavity.

(2) Laser Q-Switch. - Th e ai r-dr iven Q-switch presently

used in the Mark V presents severa l difficulties: a

source of compressed air is necessary, which usually

requi res th e us e of some form of air c o m p r e s s o r. In

addition, changes in ai rcraf t altitude cause variations

in turbine speed.

Saturable-dye passive Q-switches fo r Neodymium

lasers are still under development, and no presently

available dye is entirely satisfactory fo r the applications

discussed here.

A good alternative solution is an elec t r ic -motor driven

Q-switch. These i tems a re currently available and could

34



be readily adapted to p r e s e n t equipment.

(3) Laser P o w e r Supply. - The t ransmit ter power supply

presently used with the Mark V l idar is designed to

operate directly from the 28 volt dc electrical supply

of the ai rcraf t , thus eliminating the bulky an d inefficient

conversion equipment necessary to produce 110 volt

power either at 60 Hz or 400 Hz.

C. Data Process ion System*

1. Introduction

Th e pr imary tasks of any l idar data processing system are to

record the raw data, process these data, an d display the results in a

convenient, meaningful form. Some form of computer process ing will

certainly be required to cope with the volume of data generated by air-

borne l idar observations. Th e m a j o r problem becomes one of recording

and convert ing the raw data into proper form for input to a computer.

Many possible designs (of varying degrees of sophist ication)

could he formulated; however, the decision regarding the b e s t approach

fo r a given time period should be based on the relative importance attached

to various performance cr i ter ia such as (1) the amount of data to be re -

duced; (2 ) the accuracy desired; (3) how quickly the results ar e required;

and (4) the overall costs of acquiring and operating the data reduction

system.

Severa l examples of data process ing sys tems are described below

By J. W. Oblanas. Note: Since this section was prepared , alternativeproposals have been submitted to Lawrence Radiation Labora tory forpossible use in the BUGGY exper iment .

35



to i l lustrate the variety of methods that are feasible using present -day

technology.

2. Analog Data Storage

A minimum useful system would us e a magnetic disc r e co rde r as

a buffer storage element. That is, each l idar shot would be recorded on

the disc, and a number of recordings (approximately 10) could be played

back repetitively (a t 30 t imes a second) into a conventional oscil loscope

(o r into a storage oscil loscope). One possible form of display could take

5the form of a contouragraph, which has range, signal ampli tude, and

observation time as coordinates. This display, along with navigational

data, could provide th e airborne controller with enough rea l - t ime to enable

the ai rcraf t to properly track the sub-visible cloud. At the en d of each run,

the data recorded on the disc could be converted to digital form and re -

corded on magnetic tape fo r later analysis by computer. Th e computer

could apply various analysis techniques and present data regard ing cloud

size, volume, density variations, etc.

Th e video disc r e co rde r presents some mechanica l disadvantages

( l imited lifet ime of the disc an d record ing head) when operated fo r extended

periods of t ime. This approach is unlikely to be th e most reliable, parti-

cularly in view of the mechanical problems inherent in subjecting a device

rotat ing at high speed to the accelerations encounterd even in smooth

flight.

3. Digital Storage of Data

Rapid developments in the field of digital integrated circuits m ay

soon make possible the construction of high speed digit izers suitable for

l idar us e at a cost lower than that of the video disc slow-speed digit izer

36



discussed above. The high-speed digitizer will be able to process a

larger number of data points with greater accuracy than is possible with

the video disc arrangement. Fo r example, a currently available integrated

circuit digitizer can divide an analog waveform into 10Z4 samples each one

microsecond long, digitize each of these samples to 5-bit accuracy, and

store the resulting values in a magnetic core memory.

One possible use of a suitable high speed digitizer would be to

replace the video disc described earlier. Each lidar shot would be digi-tized immediately and stored on magnetic tape. The stored data could be

displayed on a storage oscilloscope to provide real-time tracking data.

The tape would later be fed into a computer to provide a detailed analysis

of the cloud structure, etc.

4. A Second-Generation Data Processing System

For both of the systems described previously, the real-time dis-

play is limited only to the raw lidar data. These data must be combined

with manually plotted navigational data to yield the information necessary

for effective cloud tracking. The reduction of the lidar data must be sub-

sequently performed by a ground-based computer. The experience gained

during routine airborne lidar cloud tracking (or the demands of future

applications) may show the desirability of combining the reduced lidar

data with navigational data on one real-time display.

It is interesting to speculate about further improvements to the

lidar data processing system in the event that real-time processing and

display of a large amount of data become necessary. The main reason

for the following discussion is to describe the increased observational

capability of the lidar system that could be provided by the use of

37



computer-cont ro l led displays.

One possible solut ion of the problem of process ing high data rate

signals is to replace the oscil loscope display of ra w data with a smal l

computer and cathode-ray tube display that would become a permanent

component of the l idar data processing system. The full- t ime us e of a

computer fo r such an application is no t as unreasonable as it might first

appear. Small , relat ively inexpensive computers have already found

numerous applications in s imi lar full- t ime tasks, such as controlling the

production line testing of electronic components, calculating steering

signals fo r large radar antennas, and as a general-purpose da ta - reduc t ion

computer aboard research ai rcraf t . Because of the rapid advances in

integrated-circuit technology, the cost of these smal l computers ha s been

steadily decreas ing . One advantage of an on-line computer is to allow

the acceptance and storage of the digital data at the rate they are generated.

A much more s '_nificant advantage would be that an on-l ine computer will

allow the us e of a radar- type cathode ra y tube display. Th e computer

could be progran-ined to accept , store, and reduce the l idar an d naviga-

tional data, store the results , and sequentially display the results on the

CR T in a number of different ways. The us e of a computer as a data

storage element will allow the l idar display to perform in a manner

analogous to the various displays cur ren t ly employed with meteorological

radars , with the significant difference that a considerable amount of

digital processing will be performed on the l idar data pr ior to display.

Other forms of data fsuch as radiation levels and particle count data)

pert inent to a given experiment could be fed into the computer and super-

imposed on the diqplay along with the lidar data. The computer could also

38



a c c u m u l a t e naviLat ional an d nmeteorolr ) , ica l da ta , an d d i sp lay th e pred ic ted

locat ion of th e rlid to ai d ;n effe , t : , . . rac , i -. T he i ',r ; , ,, d be

r e t a ined on th e d i sp lay as i',n• a s ,1,-. rd

F o r examnple, assunme th e ] idar is used to n ak e a nu n b e r of

obse rva t ions du rl r. a run past th e c luod. TI-f con ipu ted va lues ,f spa t i a l

b a c k s c a t t e r funct ion compu ted f rom th e ra w data could be shown on th e

C R T s i m i l a r t- th e well known rangee-;inoimiith :,ul e d i sp lay, with signal

s t reng th indicated by i n t ens i ty var ia t ions . ipince th e dynamic r.ange of

i n t ens i ty var ia t ions is re la t ive ly smn•all (even fo r th e m o r e soph i s t i ca ted

CRT) , th e c o m p u t e r could be p r o g r a m m e d with a var iab le th resho ld such

t ha t only th e s to red s igna l s above a cer ta in ampl i tude would be d i sp layed .

This s igna l th resho ld could be var ied over a n u m b e r of d i s c r e t e s t eps

an d a pho tograph taken of each d i sp lay. In this w a y, th e l a r c e anmount of

p r o c e s s e d data obtained f rom an ex tended s e r i e s of o b s e r v a t i o n s cru.ld

be s u m m a r i z e d in a conmpact forn, . ..... ,ninf f - r ii n~ediat" rt':d" 'ýd

analvsis. aca', : '.. :u rjcwl'I- CV1•,, 7 , . ,1 :

ta.-,, o f tlit, asr; at t u . e c t e d tiI Ie s 1. r ci\ a pe rlnO "Ir n I' el r.I

of th e obs- rva t ; , i , : s

i -o ;I fls V u~ . . . 0 .. ' . 1 *'i

output is fed to a .inI ,vcra o,-'r, if 1.i,, t-, :' ' ra t f a , , s t i ca ted

l ida r is fas ' c-mn par, ,d t, th e 1,, ,, . iic :,qiti, ., 11 ;,.r

observat i ron, a s iona l xericer C,,ld.., .:-v iii_, t ,

th e a c c u r a c y an d sensi t ivi ty to t, e cS-. to , ;.,id lo r,.dic,-o i , .w -,,o of



o ~ 0-j

ILA

z w z

0x< 0 0

z__ ccJL

w z

1 , 0 .

az w 0 w

2, 0 0n

-1 0O Z zo 0o w

-j -.

0

ww

.ca.L)I

4(a-



data generated. The output of the a v e r a g e r, consist ing of the su m of a

number of re turn signals, is fed to th e digital computer through a scanner.

The scanner also collects auxiliary data pertaining to each shot (such as

time, navigation data, computed winds, etc.) . The ra w data a n d / o r the

averaged data ca n be viewed by m e a n s of an auxiliary moni tor osc i l loscope .

The on-l ine computer (such as th e P D P - 8 made by Digital Equipment

Corpora t ion) accepts th e ra w data, p e r f o r m s the requi red calculations,

an d s tores the resul t s in th e m e m o r y. The computer also cont ro ls the

CR T display. On command , th e computer wil l present the reduced data

on the CR T in an y one of severa l selectable forms . F o r example, a number

of displays used in r a d a r work m ay be useful (such as range-elevation

angle an d range-az imuth angle). In addition, a contouragraph display 5

that has range, signal ampli tude, an d observation t ime as coordinates

m ay be useful . A c a m e r a mounted on th e display will photograph the CR T

data. In addition, an auxiliary x-y plotter could produce a selected group

of observations in graphic form. If permanent retention of the data is

des i rab le , the reduced data in the drum m e m o r y could be per iod ica l ly

t ransfer red to magnet ic tape. Th e magentically s tored digital data ca n be

fed back into computer m e m o r y when additional ana lyses are requi red .

The precise form that future l idar sys tems will take is diff icul t

to predict . F o r one thing, the exact operational requi rements imposed

on a par t icu lar l idar will have cons iderab le inf luence on the final form of

the data sys tem. Slight var ia t ions in the operational requi rements a s s u m e d

could easily invalidate many of the discuss ions and conclusions reached

here . However, the rapid advances that are being made ii 1-hc allied fields

of integrated c i rcu i t components and in computer technology strongly

41



sugges t tha t digital data process ing will play an increasingly greater role

in operational l idar equipment.

D. Navigation

The problems of positioning the ai rcraf t with respect to an invisible

(o r a t bes t , semi-v is ib le) cloud which is moving with the wind, and to

carry ou t an effective l idar observa t iona l p rogram, a re considerable.

There were difficulties experienced in the Pre-GONDOLA II exper iment .

However, these were no t fundamental , and the exper ience gained on this

one occasion clearly points the w ay to improvements . In fact , there is

little doubt that m o s t of th e navigational problems could have been over-

come in one additional practice flight.

The Dopple r navigation system of th e type used would appear to be

wholly suitable for this operation. In this sys tem, posit ional data is

displayed to the pilot in t e r m s of (1) distance ALONG an d (2) distance

L E F T or RIGHT, of a pre - se t track. (The use of an improved compass ,

such as w as subsequently f i t ted in the ai rcraf t , minimizes th e e r ro r s to

which Doppler sys tems a re prone. ) The advantage of this sys tem lies

no t only in providing the posit ional data essential fo r keeping track of

th e posit ions of the ai rcraf t an d the cloud (and the points from which the

l idar observations are made), but in ass is t ing th e pilot in flying his ai r-

craf t accura te ly to provide an optimum observational platform.

Specif ical ly, it is recommended that the Doppler plot be oriented so

that i ts track passes through ground zero (GZ) an d para l le l with the

direction which it is expected that the cloud will follow (i. e., the wind

direction). The origin of th e Doppler plot could be a t GZ or, if des i red ,

could be a recognizable landmark sufficiently fa r upwind of ground zero

42



to ensure that all operations can be carried out without change of sign of

ALONG track distances in any run.

In this arrangement, we ar e thus provided with a rectangular coordin-

ate system in which position is experssed as distance ALONG track and

distance LEFT or RIGHT of track. (The resolution readily available

depends upon the scale setting--e. g., 100 mile along track, plus and minus

10 miles across track).

Lines on the ground can most readily be identified on this coordinate

system if they lie parallel or at right angles to the Doppler track.

Provided we are able and willing to conform to this coordinate sy'7em

in flying the observational passes, we thus have (1) a simple mechanism

for monitoring all positions and keeping a running plot of the cloud and

aircraft positions and (2) an effective method of directing the pilot in a

way with which he can most readily comply.

For example, given any assumed position of the cloud, it is desired

to position the aircraft at a specific point flying in a given direction. The

pilot is simply instructed to fly at n miles RIGHT of track from a position

m miles ALONG track. The pilot positions the airplane accordingly and

holds course to ensure that his track as indicated by the Doppler is con-

sistently n miles RIGHT of track and his distance ALONG track is in-

creasing steadily. Lidar firing operations can be begun at any desired

increment of distance ALONG track. If a pass is to be made aý right

angles to the wind direction, the pilot is instructed to fly from a position

x miles RIGHT of track to y miles LEFT of track while keeping his dis-

tance ALONG track constant at z miles. This system remains effective

even when the direction is towards the origin of the Doppler plot; ALONG

43



t rack distances ca n either be expressed as negat ive numbers ALONG

t rack or as positive numbers BACKTRACK. Th e Doppler display ha s

provisions fo r coping with rec iproca l t racks that should be exploited

appropriately in this context .

Prov ided that th e cloud remains fair ly well centered in this Doppler

coordinate system an d observational passes ca n be made along the rec-

tangular grid l ines thereof, no changes need be made in the Doppler

set t ing, even if it has drif ted. Prov ided regu la r l andmark identif icat icn

is made to t ie-in th e Doppler coordinates, an d marked into the record ,

e r ro r s ca n be el iminated and the detai led analysis adjusted subsequently

in the same wa y as a t raverse is adjusted in surveying. Unless serious

drif t e r ro r s occur, it would probably be quite satisfactory to work from

th e Doppler coordinates (even if slightly in e r r o r ) in relat ing the cloud

to the ground. Should m o r e prec ise navigation be necessary -- e. g.,

as in control l ing other ai rcraf t with high accuracy -- the necessary ad -

jus tments would have to be calculated by the navigator, with or without

reset t ing of the Doppler. Should the cloud move out of the initial grid

coverage, it would be necessary to r e s e t th e Doppler, or again, if it

became too large fo r the scale used, a scale change would have to be

made.

Th e prec i se detai ls of such a scheme would obviously need furthc..

study in the preparat ion period of an y subsequent operat ion, bu t tho b;.i:

approach appears very straightforward. It should be s t ressed , howe-.,,

that if it is necessary to relate th e l idar-observed cloud posi t ions tc. the

ground or to have a i rcraf t vectored in and around the cloud with great

pr,-cis ion, care m u s t be taken in making an y convers ions necessary fronm

44



th e l idar (arbi t rary Dopple r ) coordinate system to an y other. Such pro-

cedures would present no difficulty to a profess iona l navigator, however.

Should an ai rcraf t be employed that is no t fitted with Doppler, th e

problem of navigation would be onerous bu t no t insurmountable. Every-

thing would depend upon what other navigational aids are available, and

the skil l of the navigator and pilot team in coordination with the lidar

crew. In principle, the task is s imi lar to that familiar to mil i ta ry ai r

crews in such operations as precision bombing or laying mine pat te rns .

In the absence of Doppler, th e ass is tance of a special system of ground

m a r k s or electronic beacons would be highly desirable. It would be

essent ia l in this case to provide ample t ime fo r developing appropr ia te

techniques and practicing them in f l ight with al l the personnel involved.

E. Communications

P r o b l e m s arose on this tes t in communication between the l idar crew

An d the a ir crew.

in view of the difficulties caused by the noise of the ai rcraf t , it is

recommended that al l intercommunication be tween personnel be carr ied

nu t by te lephone headse ts (of a type designed fo r ai rcraf t in te rcom) .

T-,,o separa te transmitt ing c i rcu i t s could be provided, each recorded

,ti lane in a separa te channel. (The simple stereo audio tape recorder

used on this pro jec t is very suitable fo r this purpose. ) One c i rcu i t would

hi, iqerd fo r l idar operations, the other fo r ai rcraf t operations.

V 'c rophones would be connected accordingly. Facili t ies could be

:-,rovialed fo r switching, if des i red , although it would probably he better

to, have only the l idar d i rec tor capable of speaking into both circuits

s:iv., ' ltaneously (with appropr ia te switch control). Simi la r ar raneements

45



REFERENCES

1. M. G. H. Ligda, "The Laser in Meteorology," Discovery (July 1965).

2. R. T. H. Collis, "Lidar: A New Atmospheric Probe," Quart. J. Roy.Meteorol. Soc. Vol. 92, p. 392 (April 1966).

3. C. A. Northend, R. C. Honey, and W. E. Evans, "Laser Radar (Lidar)fo r Meteorological Observation, " Review of Scientific Instruments,Vol. 37. No. 4, pp. 393-400 (April 1966).

4. J. W. Oblanas and R. T. H. Collis, "Lidar Observations of the Pre-GONDOLA I Cloud," Report PNE-l 100, p. 74, Fig. 38 (July 1967).

5. G. N. Webb and R. E. Rogers, "The Contourograph," IEEE Spectrum,pp. 77-87, (June 1966).

47



APPENDIX

PRE-GONDOLA TECHNICAL REPORTS

Author a n d / o r Tech-

Title of Report Agency nical Program Officer Number

Pre-GONDOLA -

Seismic Site Cali- NC G M. K. Kurtz P N E - I I 0 0bration B. B. Redpath

Site-Selection NCG/Omaha H. A. Jack PNE-1101Investigations W. W. Dudley

Pre-GONDOLA I -Technical Director ' s NC G M. Y. Kurtz et al . P N E - l 102

Summary Report

Genlogic and Engineer-ln'ý Proper t ies NCG/Omaha P. R. F i s h e r et at. PNE-1103Investigations

Close-in Ground WES J. D. Day et al . PNE-1104Motion, Ear thStress , and PorePres su re Measure-mnents

i ' ter r 'edia te Range LR L D V. Power PNE-1105* -r-*Md Motion

9

t ruc tures WES R. F. Pallard PNE- 1106I f s t rvn ien ta t ion

Crater Stu ies: NCG R. W. Harlan PNE-1107Crater Nieasurements P a r t I

Curface MNotion NCG W. G. Chris topher PNE-1107P a r t II

Cioud Development NCG/LFL W. C. Day PNE-1108

Studies R. F. Rohrer

Close-in Displacement AWFL C. J. Lemont PNE-1109Studies

Lidar Observations SRI J. W. Oblanas PNE-1110of P re -GONDOLA I R. T. H. CollisClouds

48



Pre-GONDOLA I, cont 'd.

Presho t Geophysical LRL-N R. T. Stearns PNE- 1111M e a s u r e m e n t s

Pre-GONDOLA II -Technical Director ' s NCG Wo C. Da y PNE-1112

Sun-nary Repor t W. Y. Kur tz

Close- i r Ground Motion WES J. 0. Da y PNE-l113and Ear th St ress

Enti iueerina Proper t ies NCG P. R. F i s h e r PNE-1114ln 'es t iea t ions W. W. Dudley

A. D. Frandsen

Intermediate Range LR L D. Power PNE- 1115, rcund M otion

Struc tures Ins t ru- WE S R. F. Bal la rd PNE- 1116rnentation

C r a t e r Studies:Crater Measurements NC G R. W. Har lan PNE-1117

;i-d Ejecta Studies M. A. Novak P a r t I

Cr;t t r Studies:(rund Surface Motion NC G J. E. Lat te ry PNE-1117

P a r t II

CiM'd Development NCG W. C. Day PNE- 1118Studies

Ai rhnrne Lidar SRI R. T. Collis PNE-11190)W-ervations J. Oblanas

r, ,-va] of Simulated WES J. D. Da y WES TRPre-ernplaced Charges

C' - ) c - in A ir Blas t BR L J. Keefer BR L TR

pne 1119 pre-gondola 2

Documents