IN-FLIGHT RESPONSE TO A NEW NON-GYROSCOPIC BLIND FLIGHT INSTRUMENT—MOHLER & HASBROOK

turbulence conditions with no effect upon the operation
of the instrument. Due to its damped needle, turbu-
lence had no adverse effect on the instrument.

Flight Test Maneuvers—The flight maneuvers used
to test the subject’s ability to maintain control of the
aircraft consisted of “level” turns, climbing turns, diving
turns, and spirals. All turns, with the exception of
spirals, involved a 30° bank at the time control of the
aircraft was assumed by the subject. Initial bank angles
utilized in the spirals ranged between a minimum of
60° to a maximum of 105°. Control of the aircraft was
transferred to the subject on specific headings in rela-
tion to the direction of these turns; left turns at 360°
and 270°, respectively, and right turns at 90° and 180°,
respectively. No initial, specific heading was used dur-
ing entry into spirals.

Test Procedure—Prior to flight each subject was in-
formed: (1) the test objective was to provide data for
evaluation of a new type of safety instrument; (2) it
was supposed to provide the pilot with enough infor-
mation so that he could maintain the aircraft in a safe
level attitude while extricating himself from instrument
weather conditions; (3) the test would be divided into
two parts: flying the aircraft under the hood while (a)
using the Kenyon instrument with the airspeed only
and (b) using the “turn and bank” indicator with the
air speed indicator; (4) they would be given approxi-
mately 10 minutes to familiarize themselves with the
“feel” of the plane during (a) climb to altitude and
(b) during several 360° changes of direction in shallow
“level” turns—while flying with visual reference to the
ground and natural horizon; (5) the aircraft would be
trimmed for approximate level flight at a speed of 120
knots by the safety pilot; (6) the subject was not to
change the throttle or propeller settings during the test,
and (7) any further instructions would be given to the
subject over the “hot” intercom system in the aircraft
(the safety pilot and the subject were equipped with
headsets and lip microphones that operated continu-
ously without requiring use of any manual controls,
switches, etc.

The safety pilot operated the aircraft during the
following phases: starting the engine, taxiing, take-off,
descent (after completion of the tests), landing, and
return to flight line. In addition, he trimmed the air-
craft for level flight prior to initiation of the tests and
also placed the aircraft in the desired condition of bank,
speed, and magnetic heading (prescribed by the test
program) prior to turning over control of the aircraft
to the subject.

During the climb to altitude the subject was in-
structed to make climbing turns to the left and to the
right involving 90° change of direction, respectively,
using approximately 15° of bank and a speed of 90
knots. After reaching the desired altitude the safety
pilot again took control of the aircraft and set the mani-
fold pressure, rpm and trim for 120 knots cruising flight.
The subject was then instructed to make two medium
banked turns involving 360° change of direction to the
left and right, respectively. Upon completion of these
familiarization turns, control of the aircraft was again
assumed by the safety pilot while the “blind flight” hood

Aerospace Medicine * April 1966

was placed in position over the subject. Upon affirma-
tive response from the subject that he was ready for
the test to begin, the safety pilot placed the aircraft in
the appropriate maneuver, switched on the recording
camera and turned over control of the aircraft to the
subject by a voice command. Upon completion of the
maneuver (recovery to a straight and level attitude
within a maximum of two minutes—or loss of control),
the safety pilot again took control of the aircraft, placed
it in the next appropriate maneuver and instructed the
subject to again take control. Each succeeding maneu-
ver was handled in a similar manner.

After completion of the 14 prescribed maneuvers
using the Kenyon instrument (in combination with the
air speed indicator), the subject was given a five-
minute rest with the “blind flight” hood open and the
aircraft under control of the safety pilot. At the end
of this time the cover plate was removed from the
“turn.and bank” instrument and placed over the Kenyon
instrument. The hood was again put in place and the
subject was tested on his ability to control the aircraft
by use of the turn and bank instrument (in combina-
tion with the air speed indicator only) by repeating a
representative sample of the maneuvers previously used
in testing his response to the Kenyon instrument. Upon
completion of this set of maneuvers, the test portion
of the flight was terminated, the hood was raised and
the aircraft was flown back to the field and landed by
the safety pilot. Immediately after the flight the sub-
ject was queried on his subjective reactions to the use
of the Kenyon and T & B instruments, as well as to
any difference in ease of use of either one. His re-
sponses were noted for future use in the analysis and
reporting of the testing of the Kenyon instrument.

RESULTS

The flight test data shows that the subjects were able
to make consistently smooth recoveries to a wings level
attitude without any tendency to lose control of the
aircraft and without regard to the subject’s flying ex-
perience, while using the Kenyon instrument. In addi-
tion, while using this instrument, roll and yaw control
was smooth with a high degree of coordination; speed
control was surprisingly smooth among the “low time”
subjects who had only a few hours of previous “simu-
lated instrument” time; after achieving straight and
level flight, bank angle and heading were usually main-
tained within +3° for periods up to 8 minutes. Also,
average positive acceleration imposed on the aircraft
during recoveries from high speed spirals using the
Kenyon instrument was 2.24 g; average for the turn and
bank instrument was 2.75 g. Maximum positive accele-
ration for the Kenyon instrument was 3.6 g; maximum
for the turn and bank instrument was 4.0 g. Maximum
negative acceleration for the Kenyon instrument was
0.5 g; maximum negative acceleration for the turn and
bank was 0.8 g.

Recoveries to straight and level were as smooth or
smoother with the Kenyon instrument than with the
tum and bank with the exception of three subjects who

8





IN-FLIGHT RESPONSE TO’A ‘NEW NON-GYROSCOPIC BLIND FLIGHT INSTRUMENT—-MOHLER & HASBROOK

TURN AND BANK AND AIRSPEED INSTRUMENTS

Fig. 5, Pitch control comparisons
with Kenyon and T and B instru-
ment.

INSTRUMENTS

na

ey

zs

#8

z

B=

ze

Sz

oa V/

6 KENYON AND AIRSPEED
TIME (SECONDS)

120 140

TURN AND BANK AND AIRSPEED INSTRUMENTS

Fig. 6, Heading comparisons be-
tween the turn-and-bank and Kenyon
instrument.

200]

HEADING DEVIATION
{DEGREES MAGNETIC)

°

100] ae

KENYON AND AIRSPEED INSTRUMENTS

figure out what to do—only one thought process to know what
to do with the Kenyon Instrument”. (The T&B has a needle
and ball which operate independently of. one another—the Ken-
yon instrument has only a needle.)

“Could spend more time on (looking at) the airspeed when
using the Kenyon Instrument”.

“Felt more confidence with Kenyon Instrument”.

“Had confidence that Kenyon Instrument would keep me on
heading”,

“Kenyon Instrument not as sensitive to rudder inputs”.

“Kenyon Instrument has one less ‘cue’ to worry about—ball
of T&B adds to confusion”.

“Kenyon Instrument did not incite panic by rapid movement
of controls”.

“Kenyon Instrument reassuring—like mother-hen saying ‘Don’t
get excited, we'll get there’”.

“Once needle (Kenyon) centered, knew bank was decreasing
and could spend more time checking air speed”.

a feels normal to bank toward needle (of Kenyon Instru-
ment)”.

“Ball (of T&B) all over the place—had to ignore it”.

“T liked Kenyon needle”.

“Speed control better with Kenyon Instrument—could do bet-
ter_ scanning”,

“Have to concentrate too much when using turn-and-bank—
uneven scanning with turn-and-bank and air speed goes to pot”.

“Flying without a care in the world” (with Kenyon instru-
ment),

“Ym used to fying ‘steer needle’ in simulator which caused
me to turn toward the needle when using the turn-and-bank”.

“T&B required more work than Kenyon”.

“Have to pay too much attention to turn-and-bank”.

“No sweat with Kenyon”.

“Basy to fly (Kenyon)”.

“Kenyon doesn’t require much attention”.

Aerospace Medicine © April 1966

80 100 120 140 160

60
TIME (SECONDS)

“I over control with turn-and-bank”.

Kenyon easiest to use—didn’t have to worry about the ball
‘T&B)”.
‘ "Kenyon easier to fly in rough air—turn-and-bank needle
moves too much”.

Figures 6, 7, and 8 show heading and altitude com-
parisons between the turn-and-bank and Kenyon instru-
ments. The fifth maneuver (curve #5) consisted of a
recovery from a 30° banked diving turn to the left;
control of the aircraft was given over to the subject at
an air speed of 154 knots, and in a nose-down attitude
of approximately 10°. Air speed corrective action was
immediately instituted with some over-control resulting
in air speed decaying to 100 knots; air speed was then
bracketed between 120 knots (target speed) and 132
knots. The rate of turn to a constant heading was
uniform and roll angle gradually decreased to zero.
Pitch changes after the first excursion to 10° up +
varied between a maximum of 10° up and 5° down.
Maximum altitude excursion involved approximately
700 feet (during the initial air speed reduction phase)
and then remained within 170 feet.

The ninth maneuver consisted of a recovery from a
60° banked diving spiral to the left with the air speed
at 142 knots and a pitch-down angle in excess of 10°
at the time control was given to the subject. By the
time action was initiated to reduce air speed (4 seconds
after taking control of the aircraft) speed had increased
to 162 knots (maximum in this maneuver) and a 3 g
positive load was applied to the aircraft. Speed reduc-

5

20 «40



IN-FLIGHT RESPONSE TO A NEW NON-GYROSCOPIC BLIND FLIGHT INSTRUMENT—MOHLER & HASBROOK

had recent and extensive instrument flying experience
(Figure 3).

Speed control was approximately the same for both
instruments (Kenyon and T&B), with the first effect of
corrective action taking place between 4 and 9 seconds
after the subject took over control of the aircraft (Fig-
ure 4).

Continued maintenance of a wings-level attitude—
once achieved—over extended periods of time was gen-
erally better with the Kenyon instrument than with the
turn and bank.

Pitch control during recovery and return to straight

TURN AND BANK AND AIRSPEED

ROLL ANGLE (DEGREES)
RIGHT

100

TTT eo

and level was generally the same for both instruments
(Figure 5).

Subjective comments (after the flights) of various
subjects included:

“I had no difficulty in knowing which way to turn to recover”
(while using Kenyon instrument).

used no rudder—just banked toward the needle—” (Ken-

yon instrument).

“More work with the turn and bank; the needle (T&B)
jumps around too much”,

“Kenyon needle has large deflection—makes it easier to re-
cover (to know which direction to tum).”

“Kenyon instrument easier to fly”.

“Had to use two thought processes when flying the T&B to

INSTRUMENTS

Fig. 3. Comparison of recoveries
to straight and level flight between
Kenyon and conventional tum and
bank instrument,

60 80 100

TIME (SECONDS)

fan
120

pri
140 160

TURN AND BANK AND AIRSPEED INSTRUMENTS

(KNOTS)

Fig. 4. Speed control compari-
sons with Kenyon and T and B
instrument.

160
140
120

AIRSPEED

too
80

eol I

“TARGET”

AIRSPEED (20 KTS)

KENYON AND AIRSPEED INSTRUMENTS

60 80 100 120 160

TIME (SECONDS)
Aerospace Medicine * April 1966

140


Recordings were made under induced conditions of
loss of control during simulated instrument flight.

Subjects used in the program ranged from student
pilots with 6 flight hours minimum experience to com-
mercial pilots with up to 10,000 hours experience.

The device, known as the Kenyon instrument, is
self-contained, weighs 7.2 ounces, requires no vacuum
source, no electrical power, and no connection with
any moving part of the aircraft. It is non-tumbling and
not susceptible to turbulence oscillation.

The series of tests included comparisons under sim-
ilar conditions of pilot responses to a conventional blind
flight instrument display with their responses to the
new type display.

Results demonstrate a more positive and smooth con-
trol of the aircraft with the new instrument as objec-
tively measured by photographic recordings of the
flight instruments. Also, subjective measures indicate a

Aerospace Medicine « April 1966
67-3297

decreased tendency to the onset of vertigo with the new
instrument.

It is concluded that the instrument would be of
material benefit in reducing the annual toll of fatal light
plane accidents which result from loss of control by
non-instrument trained pilots who lose visual reference
to the natural horizon. It will also be of value to instru-
ment trained pilots whose conventional flight instru-
ments fail under IFR circumstances.

REFERENCES

1. Brown, Hanoxp N.: A Revolutionary New Instrument. Air
Facts, October 1963, pp. 45-51.

2, SyivanveR, R. C., and Rounns, E. W.: Direction Instru-
ments, NACA Technical Report 128, 1921, pp. 646-663.

3, Baver, L. H., Ocken, Wu.uram C., and Crane, Cant Ji:
Symposium on Blind Flying. Jour. of Aviat. Med., Vol. 1,
No. 3, 1930, pp. 127-150.

4, Eaton, N.: Aircraft Instruments. The Ronald
Press, New York, 1926, pp. 1-269.



AM 66-32

IN-FLIGHT RESPONSE TO A NEW NON-GYROSCOPIC
BLIND FLIGHT INSTRUMENT

Stanley R. Mohler, M.D.
A. Howard Hasbrook

Approved by Released by

Sled Le [fUSége€ mo
P. V. Stern, M.D.

J. R. Dus, M.D.
Cumer, Civiz Azromepican InstiToTe FeperaL Arr Surceon

September 1966

FEDERAL AVIATION AGENCY
Office of Aviation Medicine



IN-FLIGHT RESPONSE TO A NEW NON-GYROSCOPIC BLIND FLIGHT INSTRUMENT—MOHLER & HASBROOK

tion then followed almost a straight line to 94 knots
(minimum); speed then. varied between 142 and 112
knots, finally settling down to 118 knots after one min-
ute and 32 seconds from the time the subject took over
control of the aircraft.

The bank angle of 60° to the left was reduced almost
linearly to zero and then progressed to a 43° bank to
the right, prior to recovery to a constant level flight
attitude. Original altitude excursion during the first 17
seconds of recovery involved approximately 450 feet -
or a total of 900 feet; excursions thereafter involved
approximately 260 feet during the time interval of 44
to 96 seconds.

The eleventh maneuver consisted of recovery from
nose-high attitude in a partially inverted lazy-eight with
a bank of 107° to the right. The subject allowed air
speed to increase to 149 knots while reducing the bank
evenly from 107° to level flight and thence to a bank
of 37° to the left as the aircraft turned through a
westerly heading toward the south (a bank of 30° to
the left would be normal during this heading change;
the extra 7° recorded at this time probably was the
result of over control and/or lack of attention to the
Kenyon needle), Control of air speed, heading, bank
angle, pitch angle, and altitude was smooth and within
safe limits.

CONCLUSIONS

Analysis of the data results in the following general
conclusions:

The Kenyon Instrument is a “safe” instrument for use
in recovering from abnormal (or normal) attitudes to
level flight condition.

The Kenyon Instrument can be considered a “back-
up” safety instrument during IFR flight should all
“normal” flight instrument displays malfunction due to
total loss of vacuum and/or electrical power. This
applies in principle to all types and sizes of aircraft.

Level flight with the Kenyon Instrument (while in
IFR conditions) is possible on a pre-selected heading
(built into the instrument); on all other headings, some
degree of bank (up to 30°) and turn will occur (unless
a specific deflection of the needle is maintained).

Coordination during recovery from normal and/or
abnormal attitudes can be expected to be better’ (in
most cases) when using the Kenyon instrument (as
compared to using the turn-and-bank) due to the pilot’s
tendency to fly the aircraft with his “feet on the floor.”

The Kenyon instrument will continue to operate
when the aircraft is in an inverted attitude but in’ some
cases may cause the pilot to attempt return to level
flight the “long way around” (when rolling to the left
on a west heading or to the right on an east heading).

The highly damped action of the Kenyon needic
appears to be more desirable than the relatively un-
damped movement of most turn-and-bank needles.

The Kenyon Instrument apparently reduces psycho-
logical tension as well as tendencies toward vertigo, as
evidenced during the. flights and by remarks of the
subjects after the flight tests.

Use of the Kenyon Instrument should permit a pilot

6

KENYON AND AIRSPEED INSTRUMENTS

600}

FS
3
3

8
38

2

2007 I

ALTITUDE DEVIATION (FEET)
2
3
8

2
3
8

800]

1000!

° 20 40 60-80 100 ‘120

TIME (SECONDS)
Fig. 7. Altitude deviation with Kenyon instrument.

TURN AND BANK AND AIRSPEED INSTRUMENTS.

ALTITUDE DEVIATION (FEET)

Ce  )

TIME (SECONDS)
Fig. 8. Altitude deviation with the turn-and-bank instrument.

with little or no instrument flying experience to main-
tain lateral control of his aircraft while extricating him-
self from inadvertent IFR flight. This can be of value
to “pinch hitter” pilots, as advocated by Aircraft Own-
ers and Pilots Association and other groups.

SUMMARY

Human responses to a new “geomagnetic” non-gyro-
scopic blind flight instrument have been recorded dur-
ing flight utilizing an aircraft typical of those flown by
general aviation pilots.

Aerospace Medicine © April 1966


IN-FLIGHT RESPONSE TO A NEW NON-GYROSCOPIC BLIND FLIGHT INSTRUMENT—MOHLER & HASBROOK

Fig. 1. Face surface of the Kenyon instrument.

When the needle is centered (by banking toward
the needle), the aircraft will assume a bank angle rang-
ing from zero to approximately 30°, depending on the
magnetic heading of the aircraft. A maximum bank
angle of about 30° occurs as the aircraft turns to the
left through a heading of 270° magnetic. Similarly, an
approximate 30° bank to the right occurs when turning
to the right through a heading of about 90° magnetic.
Turns through other headings, either toward magnetic
north or south, result in bank angles of less than 30°,
with the bank angle decreasing in relation to the near-
ness of the aircraft’s heading to a north or south direc-
tion. A centered needle on a north heading results in
a minor bank angle of about 3°-5°; this causes the
aircraft to turn toward the south. The airplane assumes
a no turn attitude only on a south heading.

Since the instrument is designed as a “blind flight”
safety device, tests were made to determine its per-
formance during inverted flight. Tests showed that full
scale deflection of the needle (70° movement to either
side of vertical) occurs at different bank angles de-
pending on heading and direction of turn. In all cases
the needle moves to the “high” side of the bank during
a roll until an inverted attitude is reached. Therefore,
moving the stick (or wheel) toward the needle will
tend to stop the roll and return the aircraft to an “up-
right” attitude.

However, if the inadvertent roll continues past an
inverted attitude (similar to progressing through a slow
roll), the needle does not immediately shift its position
to the new “high” side. After passing an inverted atti-
tude, full scale shift, either from right to left or from
left to right, occurs at various bank angles depending
on the direction of roll and the heading. The centered
turn and bank needle during inverted flight does not
readily aid in rolling the aircraft to an upright attitude,
but rather, can lead to a “split-S” maneuver and extreme
vertical dive speeds.

MATERIALS AND METHODS

Subjects—Eleven male pilot subjects representing a
spectrum of flight skill were utilized in the test pro-
gram. Five held commercial pilot licenses (one with
an ATR), three were private pilots, and the remaining
three were student pilots. Total flying time of the

2

subjects ranged from a low of six hours to a high of
10,000+ hours, with an average of approximately 1984
hours.

Instrument flying experience of the subjects in simu-
lated and/or actual instrument conditions varied be-
tween 1.5 hours to over 5,000 hours. Ages of the sub-
jects ranged from 21 years up to and including 49 years.

Test Aircraft—A Beechcraft T-34B Mentor was uti-
lized for the tests because its weight, performance and
flight characteristics closely resemble those of the gen-
eral aviation airplanes flown by a large percentage of
private pilots. The rear cockpit of the plane was
equipped with a “blind flight” hood (Figure 2). The
hood covers the pilot-subject during the tests, and pre-
vents outside reference to the terrain. The test instru-
ment was installed on the top center of the rear instru-
ment panel and cover plates were placed over all flight
instruments on the panel (including the magnetic com-
pass) with the exception of the air speed indicator. The
air speed indicator provides airplane pitch information.

Photographic Coverage of Front Cockpit Instruments
for Data Recording—An Auto-Max-G-1 data recording
camera was installed on a special camera mount be-
tween the two cockpits. The camera was located
behind and to the upper right of the safety pilot (in
the front cockpit) and recorded all pertinent readings
on the front instrument panel. Natural light in the
cockpit was augmented with a continuous light sup-
plied by a Sylvania “Sun-Gun” with a quartz iodide
lamp. Results of the tests were recorded on 35 mm
Eastman Plus-X motion picture film exposed at a rate
of one frame per second at £8 with a shutter speed of
1/65th second.

Flight test data recorded photographically included
the following: airspeed, heading, attitude in roll and
pitch, altitude, rate of turn, slip and/or skid, vertical
acceleration (positive and negative) and time in hours,
minutes, and seconds.

Weather Conditions—All filmed flights were con-
ducted in VFR weather with clear and/or scattered
cloud conditions. Flight altitudes for the various tests
ranged between 5,500 ft. and 10,000 ft. MSL, depend-
ing on the existence and height of clouds. The flights
took place in an area. northwest of Oklahoma City,
Oklahoma. Certain flights were made in moderate

Fig. 2. Rear cockpit of plane equipped with “blind flight”
hood.

Aerospace Medicine © April 1966


In-flight Response to a New Non-Gyroscopic

Blind Flight Instrument

Srantey R. Monier, M.D., and A. Howarp Hassroox

Pilot responses to a new “geomagnetic” non-gyroscopic blind
flight instrument were recorded during flight, utilizing an aircraft
typical of those down by many general aviation pilots.

Data were obtained under induced conditions of loss of control
during simulated instrument flight utilizing subjects ranging from
student pilots with as little as 6 hours flight time to commercial
pilots with up to 10,000 hours experience.

The device used in tests of human response during simulated
blind flight is the Kenyon Instrument. This is a small, light
weight, self-contained instrument which requires neither elec-
trical power nor vacuum source. It is non-tumbling and is not
susceptible to turbulence.

Comparisons of pilot response with the Kenyon Instrument
and the conventional “turn and bank” instrument were an
integral part of the tests. More positive and smooth control was
obtained with the new instrument. Also, there was a marked
decrease in onset and severity of vertigo with the Kenyon In-
strument.

INV NOVEMBER 1963, a late model popular four-place
light aircraft was flying at 5,000 feet under radar
control in IFR conditions over Ohio. Soon after a com-
munication with Approach Control, the instrument-
rated pilot reported that the turn and bank indicator
and the artificial horizon were becoming inoperative,
as was the directional gyro.

The pilot requested guidance to the nearest VFR
airport and took the directed heading. Shortly there-
after he reported that all of the “gyros” were now lost,
and inquired of the radar service “What direction am
I turning?” The controller observed the plane enter a
tightening right turn and directed the pilot “turning
right, stop turn or turn to left.” No acknowledgment
was received and shortly thereafter radio and radar
contact were lost. All four occupants of the aircraft
received fatal injuries in the ground impact which fol-
lowed this “graveyard spiral.”

It is not rare that aircraft experience failure in certain
portions of their power supply (in the above case the
turn and bank indicator was operated electrically).
Similiarly, vacuum supply failures are not uncommon
(the artificial horizon and directional gyro operated by
vacuum in the case at hand). This case of loss of all

Prepared for the April 26-29, 1965, meeting of the Aerospace
Medical Association, New York, New York. This paper relates
to the portion of the meeting sponsored by the Flying Physicians
Association. opinions or conclusions contained in this re-
port, are those of the authors, and are not to be construed as
necessarily reflecting the views of the Federal Aviation Agency.
Dr. Mohler is Director of the Civil Aeromedical Research Insti-
tute and Mr. Hasbrook is Chief, Flight Research Operations,
CARI. Effective December, 1965, Dr. Mohler became Chief,
Aeromedical Applications Division, Office of Aviation Medicine,
FAA, Washington, D. C.

electrical and vacuum blind flight instruments is de-
scribed in Civil. Aeronautics Board accident docket
number 22398. It should be pointed out that total fail-
ure of all gyro instruments necessary to blind flight is
relatively rare, but sufficient instances have occurred
to stimulate interest in the development of a back-up
instrument. It is also noted that by virtue of its sim-
plicity of use, the instrument described in this paper
is of value to non-instrument rated pilots having limited
“lind flight” experience who find themselves in instru-
ment flight conditions.

The role of gyroscopic instruments in enabling atti-
tude control of aircraft under blind flight conditions is
defined in early classical papers.*** A new non-gyro-
scopic instrument, requiring no electrical, mechanical
or hydrodynamic energy sources, and representing a
marked departure from existing attitude instruments,
has been described. .

This paper describes the results of tests by CARI
of this new instrument, known as the “Kenyon Instru-
ment.” As will be described, the data indicate that
accidents such as the above vould be prevented through
the availability of the KI as an emergency back-up
instrument.

THE KENYON INSTRUMENT

In 1962, Dr, Ross McFarland of the Harvard School
of Public Health called to the authors’ attention the
development of a geomagnetic flight orienter developed
by Mr. Ralph Kenyon of Newtonville, Massachusetts.
Arrangements were made for the acquisition of an in-
strument by CARI for testing and evaluation.

The instrument is 3X” in length, 2 3/16” in diameter.
Weight is 0.45 pounds (7.2 ounces). The circular in-
strument face display consists of a “right-left” needle,
a white center index, two small arrows pointing toward
the center index mark, and the following printed direc-
tions: “Bank toward needle” and “For straight-level-
south center needle” (Figure 1). The instrument re-
quires no vacuum or electricity for operation. The in-
strument uses lines of geomagnetic force for its opera-
tion similar to the manner in which a magnetic compass
operates. The manufacturer’s installation instructions
state the instrument should be installed on or near the
instrument panel in such a way as to minimize possible
effects of magnetic fields generated within the aircraft.
Also, the use of copper (rather than steel) mounting
screws is stated to be of importance in this regard.

The instrument was tested in several aircraft over a
three-year period. No change in operation has been
noted, and it appears that the instrument can be ex-
pected. to function indefinitely.

Reprinted from Aerospace Medicine, Vol. 37, No. 4, April 1966 1



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