~ ~~ 

NASA Contractor Report 42 50 

Interpretation of FlO6B and CV580 

In-Flight Lightning Data and Form 

Factor Determination 

T. Rudolph, J. Horembala, 

F. J. Eriksen, H. S. Weigel, 

J. R. Elliott, S. L. Parker, 

and R. A. Perala 

Electro Magnetic Applications, Inc, 

Lakewood, Colorado 

Prepared for 

Langley Research Center 

under Contract NAS 1- 17748 

National Aeronautics and 

Space Administration 

Off ice of Management 

Scientific and Technical 

Information Division 

1989 
Chapter 

TABLE OF CONTENTS 

Title 

1 INTRODUCTION 

2 ANALYSIS OF THE 1985 AND 1986 F106B TRANSIENT 

FLIGHT DATA 

2.1 Introduction 

2.2 Linear Triggered Lightning Modeling 

2.2.1 

2.2.2 

2.3 

2.3.1 

2.4 

2.4.1 

Value Correlation Study 

2.5 Summary and Conclusions 

Description of the Linear Triggered Lightning Models 

Results of the Linear Triggered Lightning Modeling 

Database Development for the 1985 Data 

Results of the Database Development for the 1985 Data 

Lightning Current Derivative Peak Value Correlation Study 

Results of the Lightning Current Derivative Peak 

3 F106B FIELD MILL MODELING 

3.1 Introduction 

3.2 

3.3 

Calculated Field Enhancements and Calibration Matrices 

Application of Form Factors to Measured Data 

4 EXPERIMENTAL DETERMINATION OF F106B FORM FACTORS 

4.1 

4.2 

4.2.1 

4.3 

4.3.1 

4.3.2 

4.3.3 

4.4 

Description of Electrolytic Tank Experiment 

Electrolytic Tank Anomalies 

Possible Explanations for Anomalies 

Numerical Validation of Experimental Techniques 

Time Domain Finite Difference Technique 

Pot e nt i al Tech n iq ue 

Comparison of Numerical and Experimental Results 

Experimental Form Factors for the F106B 

for Finite Cylinder 

5 ANALYSIS OF THE 1987 CV580 IN-FLIGHT LIGHTNING DATA 

5.1 Introduction 

5.1.1 Terminology 

5.2 General Comments 

5.2.1 Initial Responses 

5.2.2 Multiple Surges 

5.2.3 Continuing Current Sizes 

5.2.4 Type of Channel 

1-1 

2-1 

2-1 

2-2 

2-2 

2-4 

2-8 

2-9 

2-9 

2-1 0 

2-1 4 

3-1 

3-1 

3-3 

3-7 

4-1 

4-1 

4-4 

4-5 

4-6 

4-6 

4-7 

4-1 1 

4-1 2 

5-1 

5-1 

5-3 

5-5 

5-5 

5-6 

5-6 

5-8 

iii 

PRECEDING PAGE BLANK NOT FILMED 
LIST OF FIGURES 

Figure Title 

2.1 

I 2.2 

I 

2.3 

2.4 

2.5 

2.6 

2.7 

2.8 

3.1 

3.2a 

3.2b 

3.3a 

3.3b 

3.4a 

3.4b 

3.5a 

Entry Channel Geometries 

Comparison of Nose Attachment Models with the Measured Data 

for Flight 85-028 Run 001 Strike 001 

Peak Value Scatter Diagram 1 Derived from 1985 Measured 

I-dot and B-dot Longitudinal Response Data 

Peak Value Scatter Diagram 2 Derived from 1985 Measured 

I-dot and B-dot Right Wing Response Data 

Peak Value Scatter Diagram 3 Derived from 1985 Measured 

I-dot and B-dot Left Wing Response Data 

Peak Value Scatter Diagram 4 Derived from 1985 Measured 

I-dot and D-dot Forward Response Data 

Peak Value Scatter Diagram 5 Derived from 1985 Measured 

I-dot and D-dot Tail Response Data 

Peak Value Scatter Diagram 6 Derived from 1985 Measured 

I-dot and D-dot Right Wing Response Data 

F106B Showing Field Mill Locations 

Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 14 Seconds) 

Calculated Ambient Fields Just Prior to the Strike for the 

Finely Modeled F106B (Strike Time Is at 14 Seconds) 

Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 48 Seconds) 

Calculated Ambient Fields Just Prior to the Strike for the 

Finely Modeled F106B (Strike Time Is at 48 Seconds) 

Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 40 Seconds) 

Calculated Ambient Fields Just Prior to the Strike for the 

Finely Modeled F106B (Strike Time Is at 40 Seconds) 

Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 15 Seconds) 

2-3 

2-7 

2-1 1 

2-1 1 

2-1 2 

2-1 2 

2-1 3 

2-1 3 

3-4 

3-9 

3-1 0 

3-1 1 

3-1 2 

3-1 3 

3-1 4 

3-1 5 

V 
Figure 

LIST OF FIGURES 

Title 

5.8 E-Field and Current Sensor Records from Flash 7, 

11 August 1987 

5-20 

vii 
CHAPTER 1 

INTRODUCTION 

This report is the last in a series of reports [l-61 documenting the 

interpretation of lightning data gathered by aircraft in flight. A majority of the 

investigation has centered on data collected by the NASA F106B Thunderstorm 

Research Aircraft. This report also contains analysis of analog data generated by the 

CV580 aircraft flown by the Federal Aviation Administration and Wright-Patterson Air 

, 

I 

I Force Base. I 

I 

1 The current report is concerned mostly with two topics. The first is the direct I 

interpretation of data collected by the F106B and CV580 aircraft. In the case of the 

F106B, the investigation is done using finite difference computer models to predict 

lightning currents and attach points. This was done for a variety of observed 1985 

strikes to the aircraft. The measured and calculated data from these strikes was also 

subjected to statistical analysis and the information entered into a database created 

under an earlier effort [6]. The small amount of 1986 data was not considered suitable 

for making these predictions and was not included in the database. The data from the 

CV580 aircraft which was analyzed was all in the form of analog data. Because of the 

long times involved (on the order of tens of microseconds to many milliseconds) and 

the low frequency bandwidth of the data the finite difference analysis of the type 

performed on the F106B data was not possible for the CV580 data. Hence the 

analysis presented here is more in the nature of statistical analysis of data in the form 

of current bursts per second, continuing current amplitudes and durations, and the like. 

The second topic dealt with in this report is the investigation of ambient 

electric fields and charges within the lightning environment through the analysis of 

field mill data and the determination of aircraft form factors. Form factors are 

investigated both experimentally and numerically, and application is made to field mill 

data collected on the F106B in 1985. 

Individual chapters of the report can be summarized as follows. Chapter 2 

reports on the investigation of 1985 direct strike data collected on the F106B. 

Correlations between I-dot nose peak values and other sensor peak values are made 

using both measured and predicted results. These correlations show that under 

selected conditions relationships between these peak quantities can usually be 

1-1 
CHAPTER 2 

ANALYSIS OF THE 1985 AND 1986 F106B TRANSIENT FLIGHT DATA 

2.1 Introduction 

The transient flight data gathered by the F106B during the 1985 and 1986 

thunderstorm seasons [A was analyzed to examine this data set for trends and to 

numerically calculate the electromagnetic sensor transients for further data 

characterization. The study supplements work completed in previous years as a part 

of a continuing effort to understand Iightning/aircraft interaction. 

All of the events analyzed in detail in this report were from the 1985 

thunderstorm season. For various reasons explained in Reference 7, 1986 produced 

only one large tail current measurement, but because none of the time derivative 

channels produced data that 

used. 

The results of this 

was usable for this type of analysis, 1986 data was not 

nvestigation include a comparison of measured and 

calculated sensor transients for 27 separate events. The calculated waveforms were 

obtained using the linear triggered lightning model in conjunction with a lightning 

current source derived via the transfer function technique developed under an earlier 

phase [4]. As a new part of the triggered lightning analysis, four distinct lightning 

channel attachment geometries were considered for the simulations. 

To complete the data interpretation, sensor waveform characteristics were 

generated for the 27 simulated events and for 29 events from the measured data. The 

characteristics were entered into the database formed during a previous effort [6] and 

then examined for correlations relating lightning current characteristics to the 

characteristics of the external sensors. 

2- 1 
(a) Nose and Tail 

Figure 2.1 Entry Channel Geometries 

2-3 
The numerical results indicate that from the 27 strikes analyzed, 20 fall into 

the category of nose attachments, 3 were left wing attachments, 3 were right wing 

attachments and a single tail attachment case is probable for Flight 85.035 Run 005 

Strike 005. The large percentage of nose attachments witnessed in the measured 

data once again confirms the high probability of channel formation at this particular 

location on the F106B. 

The current waveforms calculated during the analysis are, in many cases, 

similar to the data obtained in previous years. There is, however, a noticeable 

occurrence of some larger amplitude transients in the new data associated with the 

peak response period as compared to those seen in past years. The appearance of 

this characteristic in the derived waveforms is easily supported through an 

examination of the corresponding flight data for these events. The data obtained from 

the D-dot sensors on the F106B is particularly useful for this type of analysis since 

these waveforms have been observed in previous data to follow the pattern 

established by the current flowing on the aircraft. 

In general, the calculated sensor transients appearing in Appendix B 

provide a reasonably good representation of the measured sensor waveforms. The 

only major discrepancies in this set occur with the amplitudes of the calculated I-dot 

waveforms when compared to their measured counterparts and with the calculated 

transients exhibiting larger than expected oscillations at both early and late time for 

certain strikes. 

A close examination of the measured and calculated I-dot transients shows 

that while the pairs generally agree in terms of overall waveshape, there remains 

some disagreement in the amplitude characteristics even after the filtering process. 

The differences noted here are probably due in part to the use of calculated 

waveforms essentially derived from differing aircraft sensors. This could result in 

differences in the derived currents which are clearly functions of not only the sensor 

type and sampling rate, but also location on the F106B surface. The addition of the 

supplementary operation of differentiation to this process might also tend to magnify 

any inaccuracies in the calculated sources. 

The oscillations which appear in some of the calculated transients, 

predominantly during Flight 85.032, have their origins in the current sources derived 

2-5 
-1 

D 

L 

0 

CO 

LL 

A 

0 

0 -1 

ti 

-2 

4 

-1 

U 

L 

0 i0 

LL 

2 

g -1 I 

0 

t' 1 

0 .2 .4 .6 .8 1.0 

T i me (Mi croseconds 1 

Flight 85.028 Run 001 Strlke 001 

- Heosured -- Predicted 

U 

\ 

(I: 

v) .4 

-- .L 

cn 

C 

-0 I 

a 

0 

f -.2 

- 

-.4 3 

0 

0-.6 I 

0 

0 .2 .4 .6 .8 1.0 

Time [Hlcrosecondsl 

Flight 85.028 Run 001 Strlke 001 

- Meosured -- Predicted 

(a) No Exit Channel 

0 .2 .4 .6 .8 1.0 

Time (Microseconds] 

Flight 85.028 Run OC1 Strike 001 

- Heosured -- Predicted 

Flight 85.028 Run 001 Strike 001 

- Meosured -- Predicted 

(b) Exit Channel on Tail Section 

Figure 2.2 Comparison of Nose Attachment Models with the Measured 

Data for Flight 85.028 Run 001 Strike 001 

2-7 
, 2.3.1 Results of the Database Development for the 1985 Data I 

Using the measured and calculated transient results, it was possible to 

produce 56 new entries in the characteristics database. From this number, 27 fall into 

the category of calculated data entries and 29 represent entries of characteristics 

obtained from the measured data. Although the relative size of this additional 

database segment is small in comparison with the 1984 section, it still represents a 

useful addition to this collection of strike characteristics. 

In addition to providing the response data required by the database 

programs and the linear modeling segment, the measured windows produced as a 

part of the database development represent a set of transients which have a form and 

record length that is similar to the raw data sets obtained in previous years. This 

makes this particular data collection important because the transients of intermediate 

size obtained during this analysis can be compared directly to the measured transient 

data obtained in the past. 

2.4 Lightning Current Derivative Peak Value Correlation Study 

The new database entries were examined for possible correlations that 

would relate lightning current characteristics to the characteristics of other sensor 

responses on the surface of the F106B. After an evaluation of the new data, the study 

focused on relationships that might exist between the I-dot peak values and the peak 

values obtained for the B-dot and D-dot sensors. These correlations, if they can be 

shown to exist, are useful for making simple predictions of sensor or current 

characteristics when measurements are unavailable. For example, a correlation might 

be used to predict a peak I-dot response from a peak D-dot response when a lightning 

attachment occurred at a point not monitored by a current or current derivative sensor. 

This brief study represents an attempt to relate the sensor characteristics 

through the use of scatter diagrams for probable nose attachment cases. The 

particular analysis was performed for the measured values obtained from strikes 

where a nose attachment geometry was supported by the transients calculated in 

Section 2.2. The limitation of the values to a single strike geometry was aimed at 

reducing the list of parameters that might influence the development of simple 

correlations. 

2-9 
*+ 

. 

: 

+t 

Figure 2.3 Peak Value Scatter Diagram 1 Derived from 1985 Measured 

I-dot and B-dot Longitudinal Response Data 

.* 

'+* 

Figure 2.4 Peak Value Scatter Diagram 2 Derived from 1985 Measured 

I-dot and B-dot Right Wing Response Data 

2-1 1 
Figure 2.7 Peak Value Scatter Diagram 5 Derived from 1985 Measured 

I-dot and D-dot Tail Response Data 

15409 

14.109 

IS& 

12.109 

11d 

- ?: lO.lOs 

0, 1 9.109 

-I 

; 8.109 - 

7~10~ 

6.109 

5.109 

4.109 

3.19 

'1.1 ,I' 1 I I 18 1'1, I'I81 

- 

- 

- 

- 

- 

- 

- 

- 

*- 

- .* + - 

+ . - + 

' * I 'I " ' ' I I' I' I' " '- 

-1.0 -.(I -.6 -.+ -.Z 0 .2 .4 .6 .E 1.0 1.2 

2-1 3 
attachment geometry tended to improve the relationships between variables, the data 

still exhibited deficiencies that limit the accuracy of simple representations. The results 

suggest that consideration of the interaction between lightning and aircraft as a 

multivariate event, including such characteristics as temperature and pressure, may be 

crucial to the development of elementary predictive tools. 

2-1 5 
CHAPTER 3 

FYO6B FIELD MILL MODELING 

3.1 Introduction 

The NASA F106B thunderstorm research aircraft carried electric field mills 

which measured the local electric field at four locations on the surface of the aircraft. 

Given a calibration of those mills, the measurements can be used to infer the ambient 

electric field intensity and direction and the net charge on the aircraft under the 

assumption that the ambient field is uniform over the volume occupied by the aircraft. 

Calibrations of the system can be performed either experimentally or analytically. The 

term "Calibration" here refers to the relationship between the local fields and the 

ambient field and charge, not to the relationship between the local field at the field mill 

and the actual output (usually in volts) of that mill. Both experimental and analytic 

techniques have drawbacks that introduce errors into the calibration. Difficulties with 

the experimental techniques are listed below. 

The net aircraft charge is difficult to measure, especially for an in-flight 

aircraft. Hence the local fields produced by net charge alone are uncertain. 

This means that only for situations in which the net charge is small can the 

calibration be reliably used. For an aircraft on the ground the potential can 

be accurately controlled. This is equivalent to the net charge if the 

capacitance of the aircraft is constant. Unfortunately the presence of the 

ground plane beneath the aircraft changes both the effective capacitance of 

the aircraft and the charge distribution from what exists in flight for the same 

potential. Hence the ground calibration is unreliable for an in-flight aircraft. 

Calibrations performed by an in-flight aircraft rely on an independent 

determination of the electric field at the location of the aircraft. Independent 

measurements can be done near the ground, assuming that the field does 

not vary much up to the altitude of the aircraft, or by tethered balloons. Even 

if the field is determined accurately, the problem of net charge discussed 

above in (1) remains. 

The analytic calibration does not suffer from the above problems, but has 

unique difficulties of its own. The net charge on the aircraft can be precisely fixed, and 

3- 1 
The locations of the field mills on the F106B are shown in Figure 3.1. The 

frequency response of the field mill system was from DC to 250 Hz. A previous report 

[6] documented some points of caution which should be kept in mind when evaluating 

the field mill system and analysis. These are repeated below for completeness. 

For those four points only, "calibration" means the relationship between the 

electric field at the field mill location and the actual output of the sensor in volts. 

1) The field mill system was considered to be developmental throughout the 

NASA F106B flight program. 

2) Because of the developmental nature, the measurements were not primary, 

and often flights were made that did not record all field mill channels. 

3) There were no satisfactory calibrations of the field mill system until 1986; 

nevertheless a number of events for three flights in 1985 were considered 

usable. 

4) A special calibration of the field mill system was performed at the end of 

1986 for the 1985 flights. That is the calibration used in the analysis 

documented here. The electronic configuration of the F106B was returned 

to the 1985 values to within component tolerances. 

3.2 Calculated Field Enhancements and Calibration Matrices 

The technique used here to calculate local field enhancements for an aircraft 

in a uniform ambient electric field is the finite difference solution of Maxwell's 

equations [9]. The ambient field is inserted as an initial condition into an empty 

problem space along one of the coordinate axes. The aircraft is then introduced into 

the problem space as a conductivity which increases in time. The conductivity is 

increased slowly so as to minimize oscillations which are caused by resonant 

behavior of the aircraft. After the conductivity of the aircraft has increased to a 

sufficiently high value, the electric fields on the surface and within the aircraft can be 

zeroed to simulate a perfectly conducting metallic object. The normal fields at the 

locations of the field mills then represent the local field enhancements. This process is 

3-3 
repeated for ambient fields along the other two coordinate directions. 

The fields for a net charge are calculated by placing a net charge on the 

aircraft. This is done by running current channels from the problem space boundary to 

the surface of the aircraft. The time domain waveforms and locations of the charging 

currents are again chosen so as to minimize resonant behavior of the aircraft. 

This process produces a matrix equation which gives the local fields at the 

field mill locations in terms of the components of the ambient field and the aircraft's net 

charge. Inverting this matrix gives one an equation for the ambient fields and net 

charge in terms of the local fields. In principle, then, one knows the ambient quantities 

as precisely as the calibration of the system allows. In practice analysis shows that 

errors in the ambient quantities can be quite large, even for calibrations that may seem 

adequate [8]. 

The matrix equations giving the electric fields at the location of the field mills 

in terms of the ambient fields and net charge are shown below as Equations 3.1 and 

3.2. Equation 3.1 is the matrix equation previously reported for the more coarsely 

modeled F106B, and Equation 3.2 is the equation for the finely modeled aircraft. Note 

that the local fields are keyed to the field mills shown in Figure 3.1 and the ambient 

fields to the coordinate system shown in that figure. Also the fields are measured in 

volts per meter and the net charge in microcoulombs. 

ER 

EL 

EF 

EA 

-4.38 -1.46 .08 

-4.38 1.46 .08 

-2.47 0.00 1.52 

.89 .15 1.03 

507 

507 

464 

276 

3-5 
- 

.0012 .041 -.276 .311 

-.352 .352 0.00 0.00 

-.350 -.384 .905 -.265 

.00115 .00147 -.00248 .00253 

The ideal situation in these two equations would be for each ambient field to 

be dominated by one of the field mill readings. That is, one would like for one number 

to be dominant in each row. This would imply that the field mills each respond to only 

one component of the ambient field or net charge and are recording independent 

quantities. The above equations clearly do not have this property, which is in any case 

difficult to achieve in practice. 

The differences between Equations 3.3 and 3.4 are large enough that it was 

deemed useful to repeat the analysis of the field mill data done in Reference 6. The 

application of the new matrix equation and comparison with older results is the subject 

of the next section. 

3.3 Application of Form Factors to Measured Data 

The observed field mill data used in this chapter were digitized by hand from 

hard copy records provided by NASA. The calibrations from sensor output to local 

electric field value were provided by NASA from a 1986 calibration as mentioned in 

Section 3.1. These calibrations are shown below, where the number is for a full scale 

reading . 

ER record: 227 kV/m 

EA record: 216 kV/m 

EL record: 232 kV/m 

EF record: 248 kV/m 

3-7 
10 

c 05 

Time [secsl 

Ex Field 

TRIGGER TIME = 19:31:34.8 

F 1 ight 85-26 

10 

0 

b -10 J 

al 

E 

L 

al 

01 

4 

-20 

-30 a 

c1 

g -40 

0 

Y -50 

-60 

-70 

0 2 4 6 8101214 

Tine isecsl 

Ez Field 

TRIGGER TIME = 19:31:34.8 

F1 ight 85-26 

L 

u 

0. 

n -5 

d $ -10 

0 

d - -:5 Y 

-20 

-25 

.6 

.4 

0) 

n 

g .2 - 

3 

0 

0 

=o d - 

E 

-. 2 

-. 4 

0 2 4 6 8101214 

Time lsecsl 

Ey Field 

TRIGGER TIME = 19:31:34.9 

Flight 85-26 

1 

0 2 4 6 8 101214 

Tine (sees1 

Q 

TRIGGER TIME = 19:31:34.8 

F1 ight 85-26 

Figure 3.2a Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 14 Seconds) 

3-9 
100 

80 

t 60 

40 

0 20 

a 

L 

(I 

50 

g -20 

c. 

0 

L.. 

-40 

-60 

-80 

0 10 20 30 40 50 

Time (secsl 

Ex Field 

TRIGGER TIME = 20:13:15.2 

Flight 85-26 CBH - FH 

lSO I------ 

100 } I 

L 

a, 

2 

50 

L 

al 

v) 

2 

0 

O.0 

g -50 

-100 

4 

- 

4 

Y 

-150 

0 10 20 30 40 50 

Time [secsl 

Ez Field 

TRIGGER TIME = 20: 13: 15.2 

Flight 85-26 C@H - FH 

60 

$ 40 

c 

P) 

n 

a 

20 

0 

bo 

CI 

--I 

Y 

-20 

0 10 20 30 40 50 

Tis [secs) 

Ey Field 

TRIGGER TIME = 20: 13: 15.2 

Flight 85-26 CBW - FM 

.8 

.s 

.4 

-. 4 

-.6 

-.e 

0 10 20 30 40 50 

Time [secsl 

Q 

TRIGGER TIM = 20:13:15.2 

Flight 85-26 CEW - FH 

Figure 3.3a Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 48 Seconds) 

3-1 1 
L 

0 

E 

6o 

40 

c 

L 

3 20 

00 

2 -20 

a 

(D 

0 

> 

0 

Y 

- -40 -. 

-60 

t 

-80 

0 10 20 30 40 50 

Tine [secsl 

Ex Field 

TRIGGER TIME : 19:51:21.8 

Flight 85-26 Caw - FH 

100 - 

L 

3 

a, 

L 

a, 

a 

v) 

4 

a, 50 - 

0- 

-50 3 d 

poo - 

0 

Y --150 - 

-200 - 

-250 

0 10 20 30 40 SO 

Time [secsl 

Ez Field 

TRIGGER TIME = 19:51:21.8 

Flight. 85-26 CBW - FM 

20 

b 10 

€0 

a 

u 

L 

0 

n 

4 

-10 n 

1 p -20 

0 

Y 

d 

-30 

-40 

-50' " " " " * ' 

0 10 20 30 40 50 

Time lsecsl 

Ey Field 

TRIGGER TIME = 19:51:21.8 

Flight 85-26 CRW - FII 

.6 

.4 

.2 

n 

-0 

cn 

E 

0 

3 

0 

0 

c. - -.2 - - 

E -.4 

-. 6 

-.a 

i 

0 IO 20 ?O 00 50 

Tine [secsl 

Q 

TRIGG€R TIHE = 19:51:21.9 

F1 ight 85-26 EW - FH 

Figure 3.4a Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 40 Seconds) 

3-1 3 
80 

60 L 

al 

4 al 

E 

al 

Q. 

cn 

4 

0 

> 

0 

L 40 

- 20 

d - 

*o 

-20 

0 2 4 6 8 10 12 14 16 

Tine [secsl 

Ex Field 

TRIGGER TIME = 18:32:45.9 

Flight 85-28 CEW - FH 

5 

0 

2 -5 

L 

Q) 

al 

E 

b -10 

=’. -15 

- -20 

-25 

a 

In 

0 

> 

0 

Y 

4 

-30 

0 2 4 6 8 10 12 14 16 

Time (secsl 

Ez Field 

TRIGGER TIME = 18:32:45.9 

Flight 85-28 CBH - FH 

16 

14 

‘u 12 

d 

p 10 

$8 

26 

CI 

0 

24 

32 

CI 

0 

-2 

0 2 4 6 8 10 12 14 16 

Tine [secsl 

Ey Field 

TRIGGER TIME = 18:32:45.9 

Flight 85-28 CBW - FM 

.4 

.3 

n 

CI .2 

- *1 

EO 

m 

E 

0 

J 

0 

- 0 

CI 

4 

-. 1 

.L 

0 2 4 6 8 10 12 14 16 

Tine [secsl 

Q 

TRIGGER TIHE 2 18:32:45.9 

Flight 85-28 c8w - FH 

Figure 3.5a Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 15 Seconds) 

3-1 5 
20 

0 

2 -20 

-40 

c 

P) 

PI 

E 

a 

m 

0 

> 

0 

Y 

2 c. -60 

- -80 -. 

I.I.I.III. -loo -120 

0 

c 

2 4 6 8101214 

Time [secsl 

Ex Field 

TRIGGER TIME = 17:04:44.2 

F1 ight 85-29 CEW - FH 

-.4 

m 

n 

cI -.6 

-.8 

-1.0 

E 

0 

J 

0 

0 

r. 

4 

E 

200 - 

L 

P) 

2 

150 - 

L 

P) 

0) 

0 

Yo0 - 

6 50 

c 

- r. 

--. 

X 

0- 

- 

- 

- 

- 

30' " * " ' * ' " " " 

0 2 4 6 8101214 

Tine [secsl 

Ez Field 

TRIGGER TIME = 17:04:44.2 

Flight 85-29 CBH - FM 

20 

15 

10 

u5 a 

2 

L 

30 

; -5 

L 

0 

CI - 

y -10 

-15 

-20 

-.2 O! 

-l.* t 

-1.41 ' ' ' ' ' ' ' ' ' 

0 2 4 6 8 10121'4 

Tine [secsl 

Q 

TRIER TIHE 2 17:04:44.2 

Flight 85-29 CBW - FH 

Figure 3.6a Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 13 Seconds) 

3-1 7 
20 

10 

IL 

a3 

3 

a0 E 

L 

a3 

0. 

cn 

3 

0 

-10 

d 

0' -20 c( - 

IL 

-30 

-40 

80 

60 

3 40 

20 

L 

P) 

E 

a 

07 

0 

40 CI 

6 - -20 

-40 

M 

Y 

3s 

30 

25 

L 

Q) 

0) 

4 

90 

CI 

0 

; 15 

U 

0 5 10 15 20 25 30 0 5 10 15 20 25 30 

Tine [secsl 

Ex Field 

TRICGE4 TIME = 16:54.:22.9 

Flight 85-29 CaH - FM 

-60 

0 5 10 15 20 25 30 

Time [sees] 

Ez Field 

TRIGGER TIME = 16:54:22.9 

F1 ight 85-29 CBW - FM 

Time [secsl 

Ey Field 

TRIGGER TIME = 16:54:22.9 

F1 ight 85-29 RW - FM 

.1 

0 

-. 1 

n 

- -.2 

-.3 

-.4 

-. 5 

cn 

E 

0 

3 

0 

0 

CI - 

E 

-. .- 6 

0 5 lo 15 20 2s 30 

Tine [secsl 

Q 

TRIGGER TIHE = 165422.9 

F1 ight 85-29 c9w - FH 

Figure 3.7a Calculated Ambient Fields Just Prior to the Strike for the 

Coarsely Modeled F106B (Strike Time Is at 28 Seconds) 

3-1 9 
, components and net charge just before the strike occurred. The results of this analysis 

are shown in Tables 3.1, 3.2, and 3.3. Also shown is the total field calculated from the 

field components. The strike times shown in the tables should be considered 

approximate, in that they were read directly from the hard copy of the field mill 

observations. The electric fields are shown in kilovolts per meter and the net charge in 

microcoulombs. 

I TABLE 3.1 

Derived Ambient Field Components for Strikes of Flight 85-026 

(Finely Gridded Model) 

Strike Time Ex E, EZ Et Q 

19:31:34.8 77.6 9.2 -69.9 104.8 566.8 

19:51:21.8 -36.6 56.7 -1 2.0 68.5 -370.6 

20:13:15.2 87.3 -30.8 -65.1 113.2 604.0 

20:16:30.2 5.7 -1 7.1 -24.7 30.6 4.4 

TABLE 3.2 

Derived Ambient Field Components for Strikes of Flight 85-028 

(Finely Gridded Model) 

Strike Time Ex E, EZ Et Q 

18:32:45.9 70.1 0.0 -29.1 75.9 469.0 

3-2 1 
properly. The cause for this behavior is unknown but could be due to the presence of 

water, electrical corona, or some other unknown agency. 

2) The field mill Dlacement is SUC h as to D reclude accu rate ca libration 

This was referred to earlier in the "coupling" between the waveforms of Ex 

and Q. This is caused by the placement of the field mills on the aircraft. The coupling 

occurs because the mills respond too strongly to certain components of the ambient 

field and charge (because of their location), and too weakly to other components. 

3) The assu motions of the analvsis are not sat isfied 

The assumption made in the analysis is that the ambient field is uniform over 

some volume which encloses the aircraft. If this is not satisfied the analysis technique 

cannot succeed, and the derived fields are in error by an unknown amount. Possible 

ways in which this may not be satisfied are in having charge centers too near the 

aircraft, or in having a natural lightning channel appear near the aircraft, triggering a 

branch to the (charged) channel. 

3-23 
CHAPTER 4 

EXPERIMENTAL DETERMINATION OF F106B FORM FACTORS 

I 

I 4.1 Description of Electrolytic Tank Experiment 

The electrolytic tank for the experimental determination of aircraft form 

factors was designed as an alternate method to the charge transfer technique used 

earlier [5]. In the earlier work it was felt that the introduction of probes into the 

enhanced electric field regions was disturbing the local field distribution and therefore 

producing inaccurate results. The electrolytic tank has the advantage of using nonintrusive probes, as will be described shortly. During the course of the experiment, 

several factors were discovered that created non-ideal conditions in the tank. These 

factors are described in Section 4.2. In this section the ideal experiment is described. 

I 

A schematic of the electrolytic tank is shown in Figure 4.1. Also shown is a 

nominal (spherical) test object. The tank is filled with a copper sulfate electrolyte 

solution, and has large (approximately 1 meter square) copper plates located on two 

sides. The plates are just slightly smaller than the dimensions of the tank itself and 

therefore nearly cover either side. They extend above the electrolyte solution by 

several inches, providing a convenient place for electrical connections. The plates are 

connected directly to a voltage source which provides the overall current for the 

electrolyte. The voltage source can be either direct or alternating; during this 

experiment an alternating 60 Hz voltage was usually used. 

One of the plate electrodes is instrumented with a small circular (1/8 

diameter) probe, which is actually a small electrically isolated region of the plate. This 

is done in order to measure the local current density on the plate. There were actually 

three such probes on the plate, but in general only one was monitored at a time. The 

current densi?y on the plate is related to the local electric field at that location thro'ugh 

the conductivity of the electrolyte, so the local electric field is known if the solution 

conductivity is known. For form factor determination, however, the conductivity need 

not be known, as the form factors are a ratio of current densities at the test object and 

the plate. 

For an accurate determination of current density at the plate, care must be 

taken to ensure that the plate and the plate probe are at the same electrical potential. 

4- 1 
This is the purpose of the voltmeter and variable resistor combination on the left of 

Figure 4.1. The resistor is adjusted until the voltmeter reads zero (within noise limits). 

The test object is instrumented in much the same way as the plate electrode. 

The object is metalized with a small circular region electrically isolated. The circular 

region (probe) is located at the position where a form factor is desired. An ammeter is 

used to read the current flowing through the probe region on the test object. Once 

again, for an accurate determination of the proper current density at the probe, it is 

necessary to ensure that the probe and the test object are at the same electrical 

potential. The potential of the test object is fixed by its location between the plate 

electrodes. Because the probe is at a physically different location with respect to the 

electrical center of the rest of the test object, a variable resistor must be placed in 

series with the probe in order to equalize the potentials. The voltmeter again is used 

to adjust the resistor until the potentials are equal within noise limits. 

When both voltmeters are zeroed to within noise tolerances (in practice the 

potential differences shown on the meters are minimized rather than zeroed), the 

currents are read from the two ammeters. If the electrolyte conductivity does not vary 

with location in the tank, and that the probes in the plate electrode and the test object 

are the same physical size, the form factor can be calculated as shown below. 

En JcdO Form Factor = - - - 

Eo J&o 

Form Factor = Jco (4.2) 

In principle the form factor determined using this procedure should be 

independent of the electrolyte conductivity, the magnitude of the voltage applied to the 

plate electrodes, and the location of the test object within the tank. In addition, 

because the probes used to measure currents are in essence part of the surface itself, 

ideally no probe effects should be seen. 

4-3 
4.2.1 Possible Explanations for Anomalies I 

Three possible explanations for the observed anomalies have been 

I developed. These are listed below with a brief discussion of each. 

Electrolvsis of Solution 

It was observed that during the course of the experiment, bubbles appeared 

at the surface of the fluid near the driving plates and above the location of the probe in 

the plate. This was most easily seen when the plates were driven with the largest 

potentials. This is strong evidence that electrolysis of the fluid was occurring 

somewhere on the plate, almost certainly around the probe region. It was also 

observed that the probe current readings drifted during this time. Bubbles of gas 

forming on the probe and nearby region of the plate, causing significant local 

conductivity changes, can easily account for this drift. Further evidence of this 'is that 

scraping the plate with a wooden dowel caused an abrupt change in the probe current 

readings followed by a resumption of the drift. 

Galvanic Effem 

Many of the metalized models created for the tank experiment used copper 

probes embedded in a different metallic surface. For example, the spherical model 

was painted with a silver compound, as were the F106B scale models. Because the 

probes and the rest of the surface were of different materials, small galvanic (or 

battery) effects were expected. It was hoped that these effects would be small enough 

that derived enhancement factors would not be affected. Effects were observed by 

removing the driving potential from the plates. Ideally all potential differences would 

go to zero at that point. However, potential differences on the order of a hundred 

millivolts were observed between the probes and the surrounding metal regions. 

These potential differences slowly decayed on the scale of minutes. Because of other 

problems, these galvanic effects and their magnitude were not investigated in detail. 

3) Coatinas on Plates a nd Probes 

In spite of efforts to use plates and fluid having similar metals (copper and 

copper sulfate), it was observed that coatings appeared on the copper plates. Visible 

4-5 
then the finite difference approximation to the problem of the finite cylinder in a uniform 

electric field. 

The biggest problem with the above technique is that the solution depends on 

not one but two boundary conditions. The first is the condition that the electric field be 

zero within and on the surface of the conducting cylinder (i.e., that the cylinder be an 

equipotential surface). The other boundary condition is that used to truncate the 

cylindrical problem space. Ideally this boundary condition simulates free space 

beyond the problem space boundary. In practice, however, the condition is imperfect, 

and because of this it introduces error into the static solution. The magnitude of this 

error was in the past thought to be dependent on the cell size used in the code. That 

is, if one modeled the cylinder with smaller and smaller cells in a problem space that 

was physically the same size, it was thought that the error diminished, particularly at 

locations near the cylinder. It has since been found that the effect of the outer 

boundary condition is pervasive throughout the problem space, and in fact the errors 

in the solution were found to be significantly larger for a problem space in which the 

cell size was decreased by a factor of four. 

Two numerical models of a 15" long by 1 5/8" diameter cylinder were 

constructed. One had a cell size of 1/4" and the other a cell size of 1/32". The problem 

space boundaries were placed roughly one-half cylinder length away in the r and z 

directions. Enhancement factors were found to be significantly larger for the 1/32" grid 

than for the 1/4" grid. Results for the two models are presented later in this section for 

comparison with the improved numerical solution. 

4.3.2 Potential Technique 

During the course of this task it was discovered that the finite difference 

technique for the determination of form factors on the finite conducting cylinder was 

inaccurate. Therefore a new technique was developed which does not suffer from the 

boundary condition deficiencies of the finite difference code. This technique makes 

use of the fact that one can model the conducting cylinder as a collection of surface 

patches (in this case cylindrical rings), each of which holds a uniform charge density. 

The modeled cylinder with sample surface patches is shown in Figure 4.2. The 

electric potential at any point due to a single one of these rings is easily calculated 

4-7 
as shown in Equation 4.3. It is assumed that there is no variation in the 8 coordinate 

direction, as in the finite difference technique. 

2x 

orsdrsde 

A+= J 

0 4X&o 46 + ri - 2rors case + (zs - zo)2 

, End caps of cylinder 

Here rs and zs represent the location of the source charge, and ro and zo represent 

the location of the observation point. CT is the surface charge density of the patch. The 

integration over 8 must be done even though the potential is not a function of 8. 

The analog of the outer boundary condition of the finite difference code is 

that the potential at infinity of a ring must be zero. This is a much more rigorous 

condition than that used in the finite difference code. 

Using this technique, enhancement factors on the cylinder are calculated in 

the following way. Because the cylinder is conducting, in the static limit it must 

represent an equipotential. The potential of any point on the cylinder is the sum of the 

potentials due to the charge densities on all of the patches plus that due to the ambient 

external field. Hence the potential of a patch is represented as a sum of terms 

involving all of the patch surface charge densities plus a constant term (depending on 

patch location, because of the uniform external electric field). The potential of each 

patch can be represented this way, and all of the potentials must be equal. This 

results in a matrix equation for the patch surface charge densities with the dimension 

of the matrix equal to the number of patches. The matrix equation in truncated form is 

shown below. 

4-9 
and therefore the enhancement factor theoretically approaches infinity, so very fine 

gridding is necessary to accurately determine the enhancement of points near the 

corner. However, if one is not interested in points near the corner (within .1"), as in the 

case of the experimental results, the numerical solution should be accurate to within 

the 1% mentioned above. 

It should be emphasized that the potential technique as described above is 

applicable only to cylindrical geometries. However, the technique is easily 

generalized, and has in fact been applied to three dimensional Cartesian geometries 

in a limited number of cases. 

4.3.3 Comparison of Numerical and Experimental Results for Finite Cylinder 

A comparison of the results obtained from the finite difference numerical 

technique, the potential technique, and the two experimental techniques is shown in 

Table 4.1. 

TABLE 4.1 

Comparison of Numerical and Experimental Results for Enhancement 

Factors on a Finite Length (15") Cylinder Oriented with Axis Along the 

Ambient Electric Field 

Distance from Finite Difference Potential Charge Transfer 

End (Inches) 1/32 1/4" Technique Experiment 

Electrolytic 

Tank 

.25 12.8 8.2 7.6 

.50 11.1 6.4 6.3 

1 .o 9.8 4.9 4.8 

2.0 8.1 3.6 3.5 

4.0 5.2 2.1 2.0 

6.0 2.2 0.9 0.8 

7.1 

5.5 

4.2 

3.1 

1.8 

0.7 

--- 

7.7 - 13.4 

2.2 - 5.4 

1.2 - 1.8 

--- 

--- 

4-1 1 
TABLE 4.2 

Form Factors for Fixed Sphere with Varying Probe Diameter - Test 

Sphere Diameter Is 3.3' 

Probe Diameter Measured Form Factor 

.ow 

.125" 

.173" 

:30" 

- 

Sphere Diameter 

3.3" 

2.0" 

1.5" 

1.2" 

2.68 

2.68 

2.64 

2.63 

Measured Form Factor 

2.68 

2.53 

2.44 

2.38 

TABLE 4.3 

Form Factors for Varying Sphere Diameters but Fixed Probe (.125" dia.) 

Cylinder Diameter Measured Form Factor 

TABLE 4.4 

Form Factors for Varying Cylinder Diameters but Fixed Probe (.125" dia.) 

Long Cylinders Normal to Field 

3.1" 

2.5" 

1.6" 

1.1" 

.ar 

1.63 

1.59 

1.54 

1.45 

1.40 

4-1 3 
Figure 4.3 Side View of F106B Showing Test Point Locations 

Figure 4.4 Top View of F106B Showing Test Point Locations 

4-1 5 
Huygens' surface. A potential technique solution for the F106B could be of much 

value in deciding this question. 

In summary, although the electrolytic tank has not provided the ideal 

experimental platform for measuring form factors on scale models, it has driven a 

reexamination of numerical models for form factor calculation. This reexamination has 

led to a better numerical technique which showed that a previous experimental 

procedure (charge transfer technique) produced reliable results when applied to 

canonical shapes. These results are now felt to be better than can be reasonably 

achieved using the electrolytic tank. The new numerical technique has been used to 

calculate form factors on a finite length cylinder, and the results agree well with those 

found using the experimental charge transfer technique. Although not documented in 

this report, the numerical technique has also been applied to the canonical problem of 

a conducting sphere immersed in a uniform electric field. The results agreed to less 

than 1% with the known analytical result for all points on the sphere. A desirable 

further step in the use of this technique is to apply it to the F106B aircraft so 

comparisons can be made with results from the charge transfer experiment. 

Agreement there would increase confidence in the validity of both the numerical and 

experimental procedures. 

4-1 7 
CHAPTER 5 

ANALYSIS OF THE 1987 CV580 IN-FLIGHT LIGHTNING DATA 

5.1 Introduction 

During a three year multiagency program (USAF, FAA, USN, and NASA) an 

instrumented Convair CV580 aircraft was flown from Cape Canaveral Air Force 

Station into central Florida thunderstorms at altitudes ranging from 2 to 18 kft in order 

to measure the electromagnetic environment during lightning attachments [lo]. The 

aircraft was flown into the active thunderstorm regions during the 1984, 1985, and 

1987 lightning seasons. Data from the 1984 and 1985 flights have been fairly 

extensively analyzed [lo, 111 but the 1987 data have not yet been analyzed. 

The purpose of this section is to present the first results of an analysis of the 

1987 analog data. The review focuses on the most active records of the analog data 

which were the Jnff records and the current sensor records. Also, analog data have 

limited time resolution, about 30 microseconds, and so the primary features of the data 

that can be sensibly discussed are gross structure like initial field time dependence, 

multiple surge rates, and continuing current size. 

The 1987 analog data included responses from an array of sensors. Figure 

5.1 gives a schematic diagram of the aircraft and the location of the sensors whose 

data are analyzed here. The current sensors were mounted on booms that were 

approximately three feet in length. 

Particularly active records were obtained from the forward upper fuselage 

sensor (Jnff). The data from this sensor were integrated by a passive integrator having 

a time constant of about 0.4 sec, and were DC coupled to a magnetic tape recorder. 

Other active records were obtained from current sensors on the right (I,,.,,) 

and left (11~) wings, and on the vertical stabilizer (Ivs). The responses from these 

sensors were DC coupled to the tape recorder. 

5- 1 
During the 1987 season, seven lightning flashes produced field and current 

records. Table 5.1 gives a summary of information about the seven flashes. The first 

flash, 16 July, occurred at 18 kft and all the other flashes occurred at 14 kft. Julian 

dates and times are listed in the "Notation" column. Note that for Flash 1, the Julian 

date is apparently wrong but, because it was supplied with the original data, is 

included unaltered for ease of data identification. 

The results of the analysis will be presented in two parts. First, there will be 

a discussion of some general properties of the 1987 data including the character of the 

initial Jnff changes, multiple surge rates, and sizes of continuing currents. Second, 

there will be a detailed review of the seven flashes. The initial Jnff time dependence, 

the multiple surge character, probable attachment points and the sizes of currents will 

be subjects of each detailed review. 

5.1.1 Terminology 

Several terms in this discussion will be used with specific meanings and 

where possible the terms are consistent with SAE usage. 'Flash' will refer to the entire 

set of responses measured as the lightning occurs near, or is connected to, the aircraft. 

There were seven flashes in the 1987 data and they typically lasted 0.1 sec to 1 .O sec. 

The term 'record' will be used to describe the time response of a sensor for a given 

flash. 'Surge' will refer to a well defined pulse in a current sensor record. Typically, 

surges last less than 1-2 msec, and have shapes which are first monotonically 

increasing and then monotonically decreasing. 

Certain responses in the current sensors show a multiple closely spaced 

sequence of surges sometimes with a continuing current. This will be referred to as a 

'strike'. In SAE terminology a lightning strike is an attachment to the aircraft. Here 

'strike' means an attachment and refers to currents or fields (perhaps many surges) 

that are associated with a particular breakdown and flow of current in some relatively 

short time period (often 10-20 msec). The term 'transition' will be used to describe 

changes in the Jnfi fields. Typically there are fast and slow Jnff transitions in the J,ff 

records. Often, fast Jnff transitions occur simultaneously with surges in the current 

records. 'Group' will be used to describe a set of surges, a set of transitions; and/or 

occasionally several strikes together. Groups are typically 50-200 msec long 

5-3 
and the 1987 data have flashes with as few as one group and with as many as five. 

The groups are identified by the relatively quiet periods in Jnff between the groups and 

by common characteristics of the surges. In addition to groups, there are sets of 

surges closely spaced within a group which we denote subgroups. 

In describing the sensor time records, 0 msec time will be defined starting at 

the first significant Jnff change. The starting time is marked in the records with a 

vertical line. 

5.2 General Comments 

The basic result of our analysis is that the 1987 data are similar to the 1984 

and 1985 data and show no characteristics that are contradictory to the results 

obtained before [lo]. The 1987 data taken together have several interesting trends, so 

before discussing the individual flashes, a summary of the trends will be given. 

Observations on the initial responses, the multiple surge rates, and the current sizes 

are included. 

5.2.1 Initial Responses 

Rustan et al. [lo] have identified three general shapes for initial time 

dependences in the Jnff records. They denote the shapes by categories 1 , 2, and 3 

and explain them as a triggered flash, negative leader interception, and positive 

leader interception, respectively. 

In the 1987 data, inspection of expanded data records shows that five of the 

seven flashes (1, 3, 4, 5, and 7) have category 1 initial Jnff changes. The category 1 

changes consist of three steps: the first is a relatively slow increase in the field on a 

time scale of several milliseconds, the second is an abrupt decrease in the field in less 

than a millisecond, and the third is a subsequent rise in the field at a rate comparable 

to the first step. This sequence of field changes can be explained by a triggered strike. 

Expanded data records of the remaining two of the seven flashes (2 and 6) 

show an initial Jnff change that starts with a very abrupt increase in the field, and in 

one case (event 2) there is a subsequent abrupt decrease in the field. Flash 2 

appears to be a case of the aircraft in a branch of the main channel. In this case (flash 

5-5 
TABLE 5.2 

Summary of the Multiple Surge Data for the 1987 CV580 Flights 

Flash 

1 surges 

dsec 

msec/s*' 

2 none 

3 surges 

slsec 

msecls" 

4 surges 

slsec 

msec/s*' 

5 surges 

slsec 

msec/s*' 

6 surges 

slsec 

msec/s*' 

7 surges 

slsec 

msec/s" 

AVERAGES 

Average number 

Av rate (dsec) 

Av period (mseds) 

Group A 

10 

3300 

0.33 

12 

13,000 

0.074 

None 

None 

None 

None 

None 

None 

None 

None 

None 

None 

None 

None 

10 

5454 

8.2 

Group B 

4 

800 

1.25 

7, 9 

280, 209 

3.5, 4.8 

14, 15, 7 

280, 350, 210 

3.5, 2.9, 4.8 

11 

62 

16 

4, 5, 5 

160, 167, 312 

6.3, 6, 3.2 

12 

126 

7.9 

9.5 

29 1 

4.8 

Group C 

7 

10 

10 

6 

333 

3.3 

4 

240 

4.1 

23, 12 

135, 92 

7.4, 10.8 

None 

None 

20 

21 0 

4.8 

8.4 

166 

8.8 

Group D 

None 

None 

None 

4 

250 

2.5 

9 

5 

30 

33 

None 

182 

** mseds = milliseconds per surge 

Note: Grand Average Number Per Group = 9.1 surges/group 

s/sec = surges per second 

5-7 
5.3 Flash 1, 16 July 1987 

The data for this event are shown in Figure 5.2 and the major responses are 

in Jnff, IN, and 11,. There are no significant other responses in the data records. 

The initial behavior of Jnff is like Rustan et a1.k category 1 which shows that 

this flash is triggered, i.e., the leaders propagate out from the aircraft. This initial Jnff 

shape is also observed in flashes 3, 4, 5, and 7 of the 1987 data and is the most 

common shape in the old 1984 and 1985 data as well as the newer 1987 data. 

There are three groups in this data and a summary of the surge rates and 

periods between surges is given in Table 5.3. In some cases the rates and periods 

are calculated from expanded time scale records of the data in Figure 5.2. The surges 

in the earlier groups are more closely spaced than for the later groups, and this is 

generally true in all the data. 

The left wing current shows that this wing is a significant attachment point for 

this flash. The timing of the currents in the right and left wings is similar but there are 

unequal currents in these sensors. The measured ILW current probably represents 

the total current into the aircraft, and there is a small branch of the exit channel 

attached to the right wing. 

The current record for the left wing includes two continuing currents. The 

first transfers about 10.3 C of charge and the second about 32.2 C. Table 5.3 gives a 

summary of the 1987 continuing current properties. These continuing currents show 

that the channels for this flash were in contact with substantial charge centers in the 

surrounding cloud. 

5.4 Flash 2, 30 July 1987 

The data for this flash are shown in Figure 5.3. As in flash 1, the important 

responses are in the Jnff, IN and 11, records. However this flash is substantially 

different than most of the other 1987 flashes because the process involved a branch 

attach me nt. 

5-9 
........ .... ........ .... 

...... ..... ...... ..... 

.... 

.... 

..... ........................... .... 

.... ........ ..,. .... 

.... .... ........ ....... .... ....... .... .... 

.... 

.... 

.... 

.... 

.... .................... .... .... 

.... ...... 

Figure 5.3 E-Field and Current Sensor Records from Flash 2, 

30 July 1987 

5-1 1 
................. .... 

..... 

..... ........ 

........ .......................... ..... 

..... 

..... 

..... 

..... .... .... .... .... 

.... .... .... .... .... .... .... .... 

.... 

.... 

.... 

.... 

.... ..... .... ..... 

..... 

..... 

...... 

...... .... ...... .... ...... ..... 

..... 

..... ..... ..,.. ..... ..... ...... ..... ..... ...... ..... 

....... ...... .... ....... ...... .... ....... ...... .... ........ ...... .... : 

.... .... .... .... .... .... .... .... 

.... 

.... 

.... .... ................. .................... 

.... 

.... 

........ 

......... 

...... 

........................... 

" t=O msec ., 

Figure 5.4 E-Field and Current Sensor Records from Flash 3, 

31 July 1987 

5-1 3 
.... 

.... 

.... 

.... 

.... 

.... 

.... 

.... 

.... .... ...... 

...... ....... 

....... 

....... 

....... 

....... ....... 

........ 

...................................... 

...... 

...... .... ...... .... ...... 

.... 

.... 

.... 

.... .... ...... .... ...... 

...... 

...... ...... .............. * ...... * ......... ...... 

...... 

..... 

..... 

..... 

..... 

...... 

...... 

Figure 5.5 E-Field and Current Sensor Records from Flash 4, 

4 August 1907 

5-1 5 
...... .. ...... 

.................................... ....... ....... i: 

..... ........ .... ...... ............... ^. ........ ...... ......... ........... ........... ......... ........................... ..... ...... ;j// ........ 

............................................ ........... 

......... 

........ ... ...... .......... .. ..... ........................... ........ .......... ......... ... ... ....... .......... ........................... .......... 

........ .................... ... ... ... .. .... ... :... : ..! .: ... ..: ;. .: ......... ... .... L.: j...;..; .... ...: .... .i i ... .....: ...... .......... .. . ,. . .................... ...... 

...... ...... .. .................. ........ ..... ... ......... ... .... .................. ..... ........ .. ..... ..... ....... ......... ... ... ........................... 

.. 

.... ..a::: ...................... 

..... ... ... .... ........ 

.. .. .... .. .. ... ... .. ............................. ....................... .. ... .. ... .. .. 

.. 

.................................. ..... ....... ........ 

...................... ..... ..... .... .. ........ : .... <; ....j .... i..j...:.:..:...:.. ...!j/; 

I: 

.. .. :_ :..i...i. ......... .... ........... ! .: ..:.. :. 

: . :::::. .. * .... j.. :. .:.: .... :... .... .... ...... 

............. .. 

+...;.. p.:.. i . .: .: .. :..; i$ ; 

: ..... :i:j :.* I.* 

............ .... ... .,...... ... ..................... ..... ... ! . : (D ,,; 

.... ;-.:.:o ; 

................. .. ...... 

.... : ....: : i.. .j. ..... .... ..... ... .... .. .. .. 

........ .................. ..... ...... .... ... .... .. ................ 

......... ........ ........................................ ...... .. ..... ::!! j : ...... ............. ... ... .. , ........ 

.. 

........ .... ... ...................... ............ .... ... ... :" ,Iii .............. ... 

.... ... ........ . I..'; .... ;. ... II ... ................... ........... ... ... .... ... ..... ... ....................... + ... : .... : .,..: .... a:. ... ..... .... .. .......... ....................................... ....... ...... ...... ...... 

..... !iii .......................................... 

..... ::It:: 

.. .. .:::.: i..;.:..:..:. ...... : 

....... 

-- -- 

_I 

h 

c 5 

.e 

c 

'3 

J 

c 

L 

'9 

2 

a 

ii 

v) 

m 

5-1 7 
flashes 1, 3, 4, 5, and 7. At 200 msec, the channel connected to the aircraft is 

neutralizing charges from centers in the neighboring cloud. This is unlike the channel 

in flash 2 which did not neutralize any substantial charge centers. 

The pair of currents in the right wing and vertical stabilizer at 200 msec are 

about the same size and have the same fine structure. These two currents are 

probably the only two occurring to the aircraft at the time 200 msec. There are no 

continuing currents during this time. F 

5.9 Flash 7, 11 August 1987 

The data for this flash are shown in Figure 5.8. The most activity appears in 

the Jnft sensor. There are a few responses in the right wing and vertical stabilizer 

sensors, but these responses are small in magnitude (-200A) and are very fast in 

duration compared to the currents seen in other events. They do not appear to'be 

channels carrying currents from charge centers in the cloud. 

The initial Jnff change in this flash is similar to flashes 1, 3, 4, and 5, and is 

category 1 in Rustan et al.3 nomenclature. The flash is a triggered strike. 

There are four groups in this flash with the first three (up to 300 msec) having 

the most activity. There are few surges in the current sensors and so the attachment 

points are not to the instrumented sensors and not identifiable. 

5.1 0 Summary of Conclusions. 

The main conclusion is that the principal responses in the 1987 analog data 

are in agreement with the 1984 and 1985 data. Secondary conclusions are: 

1. Multide Surae Test ing: The average number of surges (or transitions) in a 

group is 9.1, and the average number of groups per flash is 3.4. The SAE 

specification [12] is 24 bursts/flash and 20 surges/burst. Thus, the SAE specification 

envelops the data presented here. 

5-1 9 
2. maering: Most, if not all, 1987 flashes are triggered. 

3. 

smaller than the largest surge (22.5 kA) in the 1984 and 1985 data. 

Surae S ize: The largest surge seen in the 1987 data was 3.0 kA. This is 

4. Continuina Cu rrents: The largest charge transferred in the 1987 data was 

34 C. This is a little smaller than the largest charge transferred (> 100 C) in the 1984 

and 1985 data. 

5-2 1 
CHAPTER 6 

SUMMARY AND CONCLUSIONS 

The research reported here has concentrated mostly on direct interpretation 

of measured in-flight lightning data and the determination of aircraft form factors with 

application to measured field mill data. Specifically the subjects covered include: 

1) Interpretation of Digitized 1985 In-flight Data from F106B 

Analysis of the 1985 data was performed using both the linear triggered 

lightning model described in previous reports and statistical analysis. The linear 

model was used to determine lightning attach points and current waveforms. More 

flexibility was allowed in attach points than in previous efforts. Left wing, right wing, 

and tail attachments were investigated in addition to nose attachments. Also it was 

found to be necessary to assume exit channels in a limited number of cases. This was 

necessary to avoid drifts in the calculated data, corresponding to net charging of the 

aircraft, which did not appear in the measured data. A relatively small percentage of 

attachments were found to require either non-nose attachment locations or exit 

channels. The statistical analysis was performed to identify trends and correlations in 

the data. The results of this portion of the analysis were very similar to what was found 

in previous years in that, under suitable restrictions, the peak values of current time 

derivatives can be related to the peak values of the time derivatives of the magnetic 

and electric field flux densities. Measured data from the 1986 thunderstorm season 

was also considered under this effort, but because of the small quantity of high 

resolution transient data recorded, no in-depth analysis was performed. 

2) Field Mill Analysis 

This effort concentrated on an improved numerical calculation of the form 

factors of the F106B using a more finely gridded model of the aircraft. The standard 

F106B finite difference model used for a majority of past analyses has a spatial 

resolution of one meter along the direction of the fuselage axis and one-half meter in 

the other two Cartesian directions. The model used for the form factor analysis of this 

report has a spatial resolution of one-quarter meter in all three coordinate directions. 

The form factors calculated from the fine resolution model differed in a marginal sense 

from those calculated with the coarser model. The new form factors were used to redo 

6- 1 
and properties inherent in the data. This included the statistics of multiple current 

bursts and continuing currents as well as physical interpretation of channel 

attachments and propagation directions. The observed statistical behavior was also 

found to be enveloped by the SAE recommendation for a multiple burst in-flight 

environment. 

6-3 
REFERENCES 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

I 12. 

13. 

Rudolph T., and R.A. Perala, "Interpretation Methodology and Analysis of InFlight Lightning Data," NASA CR-3590, October 1982. 

Rudolph, T.H., and R.A. Perala, "Linear and Nonlinear Interpretation of the 

Direct Strike Lightning Response of the NASA F106B Thunderstorm Research 

Aircraft," NASA CR-3746, March 1983. 

Rudolph, T.H., R.A. Perala, P.M. McKenna, and S.L. Parker, "Investigations Into 

the Triggered Lightning Response of the F106B Thunderstorm Research 

Aircraft," NASA CR-3902, June 1985. 

Rudolph, T.H., R.A. Perala, C.C. Easterbrook, and S.L. Parker, "Development 

and Application of Linear and Nonlinear Methods for the Interpretation of 

Lightning Strikes to In-Flight Aircraft," NASA CR-3974, September 1986. 

Rudolph T., C.C. Easterbrook, P.H. Ng, R.W. Haupt, and R.A. Perala, 

"Experimental and Analytic Studies of the Triggered Lightning Environment of 

the F106B," NASA CR-4104, December 1987. 

Ng, P.H., R.A. Dalke, J. Horembala, T. Rudolph, and R.A. Perala, "Application of 

Triggered Lightning Numerical Models to the F106B and Extension to Other 

Aircraft," NASA CR-4207, December 1988. 

Zaepfel, K.P., and H.K. Carney, "1 985 and 1986 Direct Strike Lightning Data," 

NASA TM-100533, March 1988. 

Mazur, V., L.H. Ruhnke, and T. Rudolph, "Effect of E-Field Mill Location on 

Accuracy of Electric Field Measurements with Instrumented Airplane," Journal of 

Geophysical Research 92, No. D10, October 20, 1987, pp. 12,013-1 2,019. 

Merewether, D.E., and R. Fisher, "Finite Difference Solution of Maxwell's 

Equations for EMP Applications," Defense Nuclear Agency 5301 F (Contract No. 

DNA001 -78-C-0231,) Electro Magnetic Applications, Inc., April 1980. 

Burket, H.D., L.C. Walko, J. Reazer, and A. Serrano, "In-Flight Lightning 

Characterization Program on a CV-580 Aircraft: Final Report," AFWAL-TR-88- 

3024, Air Force Wright Aeronautical Laboratory, June 1988. 

Rustan, P.L., B.P. Kuhlman, H.D. Burket, J. Reazer, and A. Serrano, "Low 

Altitude Lightning Attachment to an Aircraft," AFWAL-TR-86-3009, May 1987 

"Protection of Aircraft Electrical/Electronic Systems Against the Indirect Effects of 

Lightning," Draft Advisory Circular, Report of SAE Committee AE4L, AE4L-87-3, 

4 February 1987. 

Hartill, E.R., J.G. McQueen, and P.N. Robson, "A Deep Electrolytic Tank for the 

Solution of 2- and 3-Dimensional Field Problems in Engineering," Proceedings 

I.E.E., Paper, No. 21 79M, October 1956. 

R- 1 
APPENDIX A 

CALCULATED CURRENT SOURCES 

A- 1 
400 

300 

- 

J 

C 

0 

3 

u 

100 

0 

-100 

-200 

0 .2 .4 .6 .8 1.0 

Time (Microseconds] 

Flight 85.023 Run 005 Strike 002 

250 

200 

- 150 

a 

Y 

-J 

al 

L 

L 

c 100 

(3 50 

F 

0 

-50 

0 

t 

.2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.027 Run 001 Strike 001 

800 

- 600 

U 

Y 

2 400 

2 200 

a, 

L 

L 

0 

-200 0 .5 1.0 1.5 2.0 

Time [Microseconds] 

Flight 85.026 Run 002 Strike 002 

300 

250 

200 

- 

a 

- 150 

50 

0 

-50 

0 .5 1.0 1.5 2.0 

Time [Microsecondsl 

Flight 85.027 Run 002 Strike 002 

A-3 
140 100 

1 20 

100 

G 80 

c 60 

5 40 

20 

0 

50 

- Y Eo 

4 4 

C al a, L L 

3 u u 

L -50 

-100 

-20 -150 

0 .2 .4 .6 .8 1.0 0 .2 .4 .6 .8 1.0 

T i me (Mi croseconds ) 

Flight 85.032 Run 002 Strike 002 

Ti me (Mi crosecondsl 

Flight 85.032 Run 003 Strike 003 

80 - 

4 60 

5 20 

0 

-20 

C 

L 

40 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

F1 ight 85.032 Run 004 Strike 004 

100 

50 

" 

- 

Eo 

4 

C al 

L 

3 

0 

L -50 

-100 

-150' " * ' " " " 

0 .2 .4 .6 .8 1.0 

Time (Microseconds] 

Flight 85.032 Run 005 Strike 005 

A-5 
200 

.. 

a, 150 

4 

C 

50 

0 

0 .2 .4 .6 .8 1.0 

Time (Mi crosecondsl 

Flight 85.035 Run 003 Strike 003 

Ti me [Mi crosecondsl 

Flight 85.035 Run 002 Strike 002 

500 

400 

4 

c 

$ 200 

c 

(= 100 

0 

-100' " * ' " " " 

0 .2 .4 .6 .8 1.0 

Time IMicrosecondsI 

Flight 85.035 Run 005 Strike 005 

A-7 
APPENDIX B 

MEASURED AND CALCULATED SENSOR 

TRANSIENTS FOR NOSE ATTACHMENTS 

MEASURED AND CALCULATED SENSOR TRANSIENTS 

FOR RIGHT WING ATTACHMENTS 

MEASURED AND CALCULATED SENSOR TRANSIENTS 

FOR LEFT WING ATTACHMENTS 

MEASURED AND CALCULATED SENSOR TRANSIENTS 

FOR TAIL ATTACHMENTS 

PAGE # 

8-2 to 8-40 

8-42 tO 8-47 

8-49 to 8-54 

8-56 to 8-57 

B- 1 
.3 

-J 

0 

0-.1 

I I 

I 

-.2"""""'""'""' 

0 .5 1 .o 1.5 2.0 

Time (Microseconds] 

F1 ight 85,022 Run 004 Strike 004 

- Meosured -- Predicted 

1.0I""I """""""1 

- .2 

-0 

cn 

C 

z 

4 

cn 

L -.2 + 

a -.4 

4 

g-.6 1 1 

0 

-.8'""'''"'""'"" 0 .5 1.0 1.5 2.0 

Time (Microseconds) 

Fl ight 85.022 Run 004 Strike 004 

- Measured -- Predicted 

al 

0 

4 

0 

P) 

L 

x 

o .6 

> .4 

- '2 

m 

d 

4 co 

x 

-.2 

-. 4 

0 .5 1.0 1.5 2.0 

Ti me (M icrosecondsl 

Flight 85.022 Run 004 Strike 004 

- Measured -- Predicted 

8-3 
41 ' I ' I ' I ' I ' 1 

LL 

4 

0 

I 0 

0 -1 

-1 

-0 

L 

0 

;0 

&2 

cn 

\ 

U 

L 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.023 Run 003 Strike 001 

- Measured -- Predicted 

L 

4 

(u 

1 

aJ 1.0 

. .8 

.4 '1 

I 

4 

0 c? -.2 

'z .3 

a, 

4 

a, 

I: 

0- 

cn 

\ 

.2 

E .1 

4 

0 

0 

A-.1 

-. 2 

0 .2 .4 .6 .E 1.0 

Ti me [Microseconds j 

Flight 85.023 Run 003 Strike 001 - Measured -- Predicted 

0 .2 .4 .6 .8 1.0 

Time IMicrosecondsl 

Flight 85.023 Run 003 Strike 001 

- Meosured -- Predicted 

8-5 
J 

Q) 

=6 

ci 

v, 

24 

0 

0 .2 .4 .6 .8 1.0 

Ti me (Microseconds] 

Flight 85.023 Run 005 Strike 002 - Measured -- Predicted 

& 1.0 

Ln 

\ 

a: 

- .5 

i .? -.5 

J 

0-1.0 ? 

li 

-1 .s 

0 .2 .4 .6 .8 1.0 

Time ~Microseconds] 

Flight 85.023 Run 005 Strike 002 

- Meosured -- Predicted 

1.0 

.8 

L al 

I: 

3 .6 

& .4 

5 .2 

m 

\ 

-.4 1 0 II 

4 i I 

-. 6 I I , , I , , , 

0 .2 .4 .6 .8 1.0 

Time (Microseconds) 

Flight 85.023 Run 005 Strike 002 

- Measured -- Predicted 

2.0 1 

II 

1.4 

0 .2 .4 .6 .8 1.0 

Time ~Microsecondsl 

Flight 85.023 Run 005 Strike 002 

- Measured -- Predicted 

8-7 
150 

\ 

t. 100 

.- 50 

UI 

C 

x 

4 

L 

mo 

.- 

E 

-$ -50 

-100 

0 

I 

m 

I 

-150l a * * . 1 

0 .2 .¶ .6 .8 1.0 

Time [Microsecondsl 

Flight 85.027 Run 001 Strike 001 

- Measured -- Predicted 

y 200 

t 

Fo 

0 

J 

m 

-200 

0 .2 .¶ .6 .8 1.0 

Ti me (Microseconds) 

Flight 85.027 Run 001 Strike 001 

- Measured -- Predicted 

1501 ' I ' 1 ' I . 1 ' 

I 

100 

2 - 50 

0) 

C 

I 

4 

J 

-4 

0 

I 

-0 

a, -50 

0 -100 

m 

-150 I I 

-200 1.1.1.11 

0 .2 .¶ .6 .8 1.0 

Flight 85.027 Run 001 Strike 001 

- Measured -- Predicted 

T i me I M i cr oseconds 1 

B-9 
25~10~ 

20x109 

15~10~ 

Y 

p) 5~10~ 

z 0 

ul 

0 

4 

0 

I 

o -5~10~ CI 

-10x109 

I' 

-15~10~ 1 I 

-20 xi 09 

0 .2 .4 .6 .8 1.0 

Time [Microseconds] 

Flight 85.028 Run 001 Strike 001 

- Meosured -- Predicted 

5 150 

I4 

-50 lY 

4 

0 c: -100 

m 

-200 

0 .2 .4 .6 .8 1.0 

Ti me [Microsecondsl 

Flight 85.028 Run 001 Strike 001 

- Meosured -- Predicted 

¶OO r-----l 

200 

150 

5; 100 

- 50 

\ 

I0 

C 

I -0 

4 

al c -50 

4 -100 

n 

I -150 m 

0 

-200 

Ti me [Hi crosecondsl 

Flight 85.028 Run 001 Strike 001 

- Measured -- Predicted 

1 

0 .2 .4 .6 .8 1.0 

Ti me [Hicroseconds I 

Flight 85.028 Run 001 Strike 001 

- Measured -- Predicted 

B-11 
5~10~ 

- 

In 

\ 

ct 

QJ ul 

0 

Z 

0 

0 

I 

0 - 

J -5~10~ 

Y 

-10x109 

- 15 xl O9 

I 

I 

tit 

1 ,,,, ,,,,, ,( ,,I I 

0 .5 1 .o 1.5 2.0 

Time [Microseconds) 

Flight, 85.030 Run 001 Strike 001 

- Meosured -- Predicted 

c-. 100 

-50 

40 

-50 

a -100 

v) 

\ 

I0 

(5 

I 

f 

0 

E 

2 

0 

0 

I 

4 

* 

-150 ___ 0 .5 1.0 1.5 2.0 

Time (Microseconds) 

Flight 85.030 Run 001 Strike 001 

- Measured -- Predicted 

150 1 I 

z 100 

- 50 

-0 

c -50 

\ 

Ifn 

C 

I 

-c, 

0) 

J 

0 

0 

-c, -100 

I -150 

a, 

-200 1 I 

-250 

0 .5 1.0 1.5 2.0 

Time [Microsecondsl 

Flight 85.030 Run 001 Strike 001 

- Measured -- Predicted 

B-13 
- 

v, 

\ 

0: 

Y 

bl 

n 

0 

Z 

J 

0 

? 

Y 

6~10~ 

4~10~ 

2x109 

-2~109 

0 

-4~10~ 

-6 XI O9 

-8~10~ 

,lo xi 09 

0 .2 .¶ .6 .8 1.0 0 .2 .4 .6 .8 1.0 

Time (Microseconds] Time (Microseconds 1 

60 

40 

c - 

0 

2 -20 

m 

C 

2 & -40 .+ 

CL -60 2 

0 

c: -80 

m 

-100 

Flight 85.032 Run 001 Strike 001 

- Meosured -- Predicted 

I -120i ” . I’ I ” ’ 1 

0 .2 .¶ .6 .8 1.0 

T i me (Microseconds I 

Flight 85.032 Run 001 Strike 001 

- Measured -- Predicted 

Flight 85.032 Run 001 Strike 001 

- Measured -- Predicted 

120 

- 100 

t 80 

v, 

\ 

60 d 

40 

a 20 

-c, 

c 

J 

$0 

dl -20 

0 

-40 

-60 

t i 

0 .2 .4 .6 .8 1.0 

Time [Mi crosecondsl 

Flight 85.032 Run 001 Strike 001 

- Measured -- Predicted 

B-15 
8409 150 

5; 100 

6~10~ 

\ 

- 4~10~ IY 

5 2x109 w c50 

-;J -2~109 K 

m 

\ cJ) 

x 

-4 

L 

P) 

Z 

mo 0 

zo 

m ' -50 

-4 

0 

0 

0 

I 

- -4~10~ 

-6~10~ 

-8x1 O9 -100 0 .2 .4 .6 .8 1.0 0 .2 .4 .6 .8 1.0 

Time [Microsecondsl Time (Microseconds1 

Flight 85.032 Run 002 Strike 002 

- Meosured -- Predicted 

Flight 85.032 Run 002 Strike 002 

- Measured -- Predicted 

I- 

- 50 

4 

"0 

4 

c al 

-I 

0 

0 

-50 

I 

-100 m 

-150 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.032 Run 002 Strike 002 

- Measured -- Predicted 

B-17 
20x109 

- 10x109 

15~10~ 

ul 

\ 

I 5~10~ 

ul 0 

$ -5~10~ 

al 

0 

z 

0 

I 

- -10x109 

-20x109 

-15~10~ 

0 .2 .4 .6 .8 1.0 0 .2 .4 .6 .8 1.0 

1 i me (Microseconds I 

Flight 85.032 Run 003 Strike 003 

- Measured -- Predicted 

Ti me (Mi crosecondsl 

Flight 85.032 Run 003 Strike 003 

- Measured -- Predicted 

- 100 cn 

\ 

c 

J al-100 

4 

0 

0 

LA -200 

-300 

0 .2 .4 .6 .8 1.0 

Ti me [Mi cr oseconds I 

Flight 85.032 Run 003 Strike 003 

- Measured -- Predicted 

B-19 
0 .2 .4 .6 .8 1.0 0 .2 .4 .6 .8 1.0 

Time [Microseconds] 

Flight 85.032 Run 004 Strike 004 

- Meosured -- Predicted 

Ti me [Mi crosecondsl 

Flight 85.032 Run 004 Strike 004 - Measured -- Predicted 

100 - 

v, 

\ 

IIn 

C 

-0 

d 

-100 i 

-J 

c 

Q) i 

0 

0 

4 -200 

I 

-300 m 

-400 

0 .2 .4 .6 .8 1.0 

Ti me (Mi crosecondsl 

Flight 85.032 Run 004 Strike 004 

- Measured -- Predicted 

B-21 
120 

100 

5; 80 

- 60 

\ 

I40 .-I 

I 

K 

4 20 

zo 

< -20 

a 

0 

1 -40 

-60 

-80 

m 

0 .2 .4 .6 .8 1.0 0 .2 .4 .6 .8 1.0 

T i me (Mi crosecondsl 

F1 ight 85.032 Run 005 Strike 005 

- Measured -- Predicted 

T i me [Microseconds I 

Flight 85.032 Run 005 Strike 005 

- Measured -- Predicted 

-J 

0 

0 

A -100 

-150 

0 .2 .4 .6 .8 1.0 

Tine [Microseconds1 

Flight 85.032 Run 005 Strike 005 

- Measured -- Predicted 

8-23 

~ 
15~10~ 

10x109 

- 

m 

\ 

a: 

aJ 

ro 

0 

Z 

0 

0 

I 

- 5x109 

4 0 

CI 

-5~10~ 

- 10x1 09 

0 .2 .¶ .6 .8 1.0 

Time [Microsecondsl 

Flight 85.033 Run 001 Strike 001 

- Meosured -- Predicted 

150 

100 

5; 50 

-0 

- -50 

\ 

IIn 

C 

I 

ti -100 

a, 

3 

-150 

I -200 m 

0 

0 

-250 

-300 

150 

; 100 

\ 

IY 

i 

-1001 " " " " " 

0 .2 .¶ .6 .E 1.0 

Time [Mi crosecondsl 

Flight 85.033 Run 001 Strike 001 

- Measured -- Predicted 

0 .2 .¶ .6 .8 1.0 

Ti me [Mi crosecondsl 

Flight 85.033 Run 001 Strike 001 

- Meosured -- Predicted 

B-25 
20x109 

15~10~ 

m - 10x109 

v) 

0 

=o 

- 10x109 

-15~10~ 

1''..I.'."..'' 

I 

\ 

I 

'I 

\ 

I 

1.1.II..I.I..~. 

0 .5 1 .O 1.5 2.0 

Time (Microseconds] 

Flight 85.033 Run 003 Strike 003 

- Meosured -- Predicted 

150 

100 

I- - 

m0 

c 

c 

5 -100 

-9 

-150 

m 

-200 

150 ; CI 

m 

\ 

t 100 ; 

rn 

C 

I 

-4 

K 

E 

- 50 : 

4 

- 0 0, 'PI/ 

-;I -50 

0 

I 

m -100 ; I 

-150 ' " " " " I ' " " " " 

0 .5 1.0 1.5 2.0 

Time [Microsecondsl 

Flight 85.033 Run 003 Strike 003 - Meosured -- Predicted 

0 .5 1.0 1.5 2.0 

Time [Microsecondsl 

Flight 85.033 Run 003 Strike 003 

- Measured -- Predicted 

8-27 
20x109 

15~10~ 

- In 10x109 

\ 

U - 

P) 5~10~ 

=o 

,! -5~10' 

cn 

0 

J 

0 

0 

-10x109 

-15~10~~ ' ' * ' * 

I 

0 .2 .4 .6 .8 1.0 

Time (Microseconds] 

Flight 85.035 Run 001 Strike 001 

- Measured -- Predicted 

300 

200 

tY 

r( 

--.I : 100 

73 

3 

4 * 

Po 

7 -100 

0 

-J 

4 

0 

m 

200 

150 

t 100 

- 

m 

\ 

CY 

;; -50 

0 

I 

m 

-100 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.035 Run 001 Strike 001 

- Measured -- Predicted 

-200 

0 .2 .4 .6 .8 1.0 

Time IMicrosecondsl 

Flight 85.035 Run 001 Strike 001 

- Measured -- Predicted 

150 

100 

- c! 50 

I- - 

-50 i 

4 

c 

: -100 4 8 -150 

m 

-200 

-250 

0 .2 .¶ .6 .8 1.0 

Ti me (Microseconds I 

Flight 85.035 Run 001 Strike 001 

- Measured -- Predicted 

8-29 
20x109 

200 

150 t 

15~10~ 

j 

; 

i 

m -10x109 

\ 

U - 

al 5~10~ 

=o 

u7 

0 

0 

0 A -5~10~ 

-10x109 

- 15x1 O9 

0 .5 1 .o 1.5 2.0 

Ti me [Microsecondsl 

F1 ight 85.035 Run 002 Strike 002 

- Measured -- Predicted 

L 

0) 

C 

x 

-4 

L 

rY 

.- 50 

030 

< -50 

-100 

.-4 

0 

I 

m 

-150~*. ' ' -. .* ' *. . " ' *. -1 I 

0 .5 1.0 1.5 2.0 

Time [Hicrosecondsl 

F1 ight 85.035 Run 002 Strike 002 

- Measured -- Predicted 

100 

0 

C 

x 

-9 

9) 

-J 

4 

0 

I 

m 

-0 

k- -50 

0 -100 

-150 

0 .5 1.0 1.5 2.0 

Time (Microsecondsl 

Flight 85.035 Run 002 Strike 002 

- Measured -- Predicted 

B-31 
15~10~ 

10x109 

Y 

-10x109 

-15~10~ 

150 

1 00 

m 

\ 

t 

- 50 

0 

C 

I 

K 

c)) 

.-4 

J 0 

-50 lx 

4 

0 

0 

I 

rn -100 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.035 Run 003 Strike 003 

- Measured -- Predicted 

100 - 

m 

\ 

Im 

C 

- 50 

+ 

=o 

4 -50 

d 

c al 

J 

0 

0 

I 

-100 m 

-150 

0 .2 .4 .6 .8 1.0 

Time [Microseconds) 

Flight 85.035 Run 003 Strike 003 

- Meosured -- Predicted 

Time (Microseconds] 

Flight 85.035 Run 003 Strike 003 

- Measured -- Predicted 

-150 

0 .2 .4 .6 .8 1.0 

T i me I M i croseconds I 

Flight 85.035 Run 003 Strike 003 

- Measured -- Predicted 

B-33 
200 

v) 

\ 

t; 100 

4 

K 

IY 

00 .-.I 

g -50 

0 

I 

rn 

-100 

-150 0 .5 1.0 1.5 2.0 

Time (Microseconds 1 

Flight 85.035 Run 006 Strike 006 

- Measured -- Predicted 

r, 

0 

0 

A -200 

-300 

0 .5 1.0 1.5 2.0 

Ti ne [Mi croseconds I 

Flight. 85.035 Run 006 Strike 006 

- Measured -- Predicted 

8-35 
20x109 

I 

i 

-25 __ xl .- O9 

0 

1 

.2 .4 .6 .8 1.0 

Time (Microsecondsl 

Flight 85.036 Run 001 Strike 001 

- Meosured -- Predicted 

< 150 I- 

- 100 

cn 

C 

2 50 

-50 rY 

-4 

0 

? -100 

m 

-150 

-200t"~ "'"" 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.036 Run 001 Strike 001 

- Measured -- Predicted 

400 

- 300 

200 

100 

mo 

.c, -100 

-200 

v) 

\ 

- 

0 

C 

U 

3 

4 

C 

0 

-I 

0 

0 

- 

t 

-300 

0 .2 .4 .6 .8 1.0 

Time [Mi crosecondsl 

Flight 85.036 Run 001 Strike 001 - Measured -- Predicted 

Time [Mi crosecondsl 

Flight 85.036 Run 001 Strike 001 

- Measured -- Predicted 

B-37 
400 

300 

\ 

t 

- 200 

0 

C 

-0 

4 

3 100 

:o 

I$ -100 

4 

cn 

C 

-J 

0 

0 

. .. -200 

0 .2 .¶ .6 .8 1.0 0 .2 

Time [Microseconds] 

F1 ight 85.036 Run 003 Strike 003 

- Measured -- Predicted 

200 1 

L 

150 t 

- 100 ; I0) 

C 

2 SO; T 

2 

07 

CY 

4 

0 

.- 

? -100 

m 

-150 z J 

-200' ' I ' ' ' I ' I ' * 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.036 Run 003 Strike 003 

- Measured -- Predicted 

.¶ .6 .8 1.0 

Time [Hicrosecondsl 

F1 ight 85.036 Run 003 Strike 003 

- Measured -- Predicted 

- 100 m 

c 

p! -100 

I$ -200 

-300 

0 .2 .4 .6 .8 1.0 

Time [Hicrosecondsl 

Flight 85.036 Run 003 Strike 003 

- Measured -- Predicted 

8-39 
MEASURED AND CALCULATED SENSOR TRANSIENTS 

FOR RIGHT WING ATTACHMENTS 

8-41 
L 

33 

P 

u 

a 

Y2 

U 

L 

L 

0 

21 

LL 

4 

0 

I 

00 I i I I 1 I "t 

-1' ' ' ' I ' ' ' ' ' 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.018 Run 002 Strike 001 

- Measured -- Predicted 

8 

L 

{6 

I: 

I 

d 

.- 6O 

[r: 

0 

-4 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.018 Run 002 Strike 001 

- Measured -- Predicted 

- 1.0 

L 

a, 

a, 

x 

4 .8 

,j. .6 

$5 .4 

v) 

\ 

d 

T; .2 

Id 

00 

? 

0 -.2 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Flight 85.018 Run 002 Strike 001 

- Measured -- Predicted 

-6 

0 .2 .4 .6 .8 1.0 

1 iine [Microseconds I 

Flight 85.018 Run 002 Strike 001 

- Measured -- Predicted 

8-43 
.6 

Y 

1.0 

D 

L 

0 

3 

LL 

tj .5 

4 

+o vL--&-d -.5 

0 .2 .4 .6 .E 1.0 

Time [Microseconds] 

Flight 85.022 Run 003 Strike 003 

- Measured -- Predicted 

2.5 

- 

L 

al 

x 

: 2.0 

& 1.5 

ln 

\ 

a: 

ol 

C 

- 1.0 

2 .5 

.? 0 

4 

Is 

E 

4 0" -.5 I 

O 

0 .2 .4 .6 .8 1.0 

Time [Microseconds] 

Flight 85.022 Run 003 Strike 003 

- Measured -- Predicted 

U 

\ .3 

a - 

-.1' * I' ' " " " 

0 .2 .4 .6 .8 1.0 

Time (Microseconds] 

Flight 85.022 Run 003 Strike 003 

- Measured -- Predicted 

.8 

.6 

- 

> 

47 - .L 

0 

> 

"0 L 

-.I 

x 

C 

I2 

m-.2 

-. 4 

-.I 

-.6 

0 .2 .4 .6 .8 1.0 

Flight 85.022 Run 003 Strike 003 

- Measured -- Predicted 

T i me I M i croseconds I 

B-45 
.4 

.3 

al 

4 

al 

t 

U 

rn 

\ 

.2 

E .I 

d - 

Eo 

&-.I 

0 

0 

-. 2 

0 .5 1.0 1.5 2.0 

Time (Microseconds) 

Flight. 85.033 Run 002 Strike 002 

- Meowed -- Predicted 

- 

> -2 

al 

3 

n -1 

0 .5 1.0 1.5 2.0 

Tine [Microseconds1 

Flight 85.033 Run 002 Strike 002 

- Measured -- Predicted 

B-47 
120 100 

80 5; 50 

60 Y 

a 20 z 

m 3 -50 

100 

\ 

Im 

\ 

co 40 4 C 

3 

-J 

C 

-I 

0 

0 

4 

.c 

E 

4 

0 

0 

-+ 0 

0 -20 

-40 

m I -100 

m 

-150 

I :::I, , , , !, ,I, , , , , , , , , , , *I 

0 .5 1.0 1.5 2.0 0 .5 1.0 1.5 2.0 -100 

Time [Microseconds] Time [Microsecondsl 

Flight 85.027 Run 002 Strike 002 

- Measured -- Predicted 

Flight 85.027 Run 002 Strike 002 

- Measured -- Predicted 

300 - 

cn 

\ 

lm 

C 

- 200 

c 

-200 

0 .5 1.0 1.5 2.0 

Ti me [Mi crosecondsl 

Flight 85.027 Run 002 Strike 002 

- Measured -- Predicted 

9-49 
100 

80 

G; 60 

\ 

t0 

I( 

K 

0 

- 40 

= 20 

40 

.+ 

* -20 

a 

2 -40 

I -60 

-80 

-100 

0 

0 

m 

0 .2 .4 .6 .8 1.0 0 .2 .4 .6 .8 1.0 

Time (Microseconds) Time (Microseconds) 

Flight 85.031 Run 001 Strike 001 

- Meosured -- Predicted 

Flight 85.031 Run 001 Strike 001 

- Measured -- Predicted 

B-51 
100 

80 - 

v) 2 60 Y 

- 40 

0 

C 

; 20 

--4 m 0 

5 -20 

3 

4 

C 

4 

I 

-40 

-60 

m 

-80 

0 .5 1.0 1.5 2.0 

T i me ( M i croseconds 1 

Flight. 85.035 Run 004 Strike 004 

- Measured -- Predicted 

120 

100 

e 80 I- 

- 60 

2 40 

0) 

C 

4 5 20 

4 

0 

y -20 

m 

-40 

0 .5 1.0 1.5 2.0 

Ti me (Microseconds) 

Flight 85.035 Run 004 Strike 004 

- Measured -- Predicted 

Time [Microseconds) 

Flight 85.035 Run 004 Strike 004 

- Measured -- Predicted 

B-53 
MEASURED AND CALCULATED SENSOR TRANSIENTS 

FOR TAIL ATTACHMENTS 

B-55 
2.0 

d 0 

g-3 

J 

LL -4 

-J 

0 

0 

70 

11 

- I1 

I1 

I1 

- I 

1.I.I. 

-1 

0 .2 .4 .6 .8 1.0 

Ti me (Microseconds 1 

Flight 85.035 Run 005 Strike 005 

- Meosured -- Predicted 

3.51 ' I ' I 9 I ' I ' J 

I: 

0- 

m 

.2.5 

2 2.0 

pl.5 

i 

-J 1.0 

;r' .5 

L 

cn 

-J 

OO ? 

OI -. 5 

0 .2 .4 .6 .8 1.0 

Time [Microsecondsl 

Fl ight 85.035 Run 005 Strike 005 

- Meosured -- Predicted 

'z 1.5 

P) 

4 

P) 

z 1.0 

U 

v) 

\ 

E .5 

1 

-1.0 

0 

: 

.2 .4 .6 .8 1.0 

Time [Microseconds) 

F1 ight 85.035 Run 005 Strike 005 

- Meosured -- Predicted 

B-57 
NASA hym 4oxaAcs .vlo Report Documentation Page *e “(lhnyracm 

1. Report No. 

NASA CR-4250 

2. Government Accession No. 

7. Author(s1 

T. Rudolph, J. Horembala, F. J. Eriksen, H. S. Weigel, 

17. Ke Words (Suggested by Author(s1) 

F166B 

Form Factors 

Electrolytic Tank 

Field Mill Calibration 

CV580 

J. R. Elliott, S. L. Parker, R. A. Perala 

18. Distributlon Statement 

Unclassif ied-Unlimi t ed 

Subject Category 47 

9. Performing Organization Name and Address 

Electro Wagnetic Applications, Inc. 

12567 West Cedar Drive, Suite 250 

Lakewood, CO 80228 

19. Securiry Classif. (of this report1 

Unclassified 

12. Sponsoring Agency Name and Address 

20. Securiry Classif. (of this page) 21. No. of pages 22. Price 

Unclassified 156 A08 

National Aeronautics and Space Administration 

Langley Research Center 

Hampton, VA 23665-5225 

3. Recipient’s Catalog No. 

5. Report Date 

September 1989 

6. Performing Organization Code 

8. Performing Organization Repan No. 

EMA- 8 9-R- 3 3 

10. Work Unit No. 

505-66-21-04 

11. Contract or Grant No. 

NASl-17748 

13. Type of Repon and Period Covered 

Contractor Report 

14. Sponsoring Agency Code 

15. Supplementary Notes 

Langley Technical Nonitor: Felix L. Pitts 

16. Abstract