Controlled visibility device for simulating poor visibility conditions in training pilots in instrument landing and flight procedure

Irwin, K. S.

English

NASA Technical Reports Server

REPLY TO 
ATTM OF: GP 
NATIONAL AERONAUTICS AND SPACE A D  
WASHINGTON, D.C. 20546 
October 15, 1970 
TO L USI/Scien t i f ic  & Technical Information Div i s ion  
At ten t ion :  M i s s  Winnie M. Morgan 
FROM ; GP/Office of A s s i s t a n t  General 
Counsel f o r  Pa ten t  Matters  
SUBJECT: Announcement of NASA-Owned 
U,S, Patents  i n  STAR 
I n  accordance with t h e  procedures contained i n  t h e  Code GP 
t o  Code US1 memorandum on t h i s  subject,  dated June 8, 1970, 
t h e  a t t ached  NASA-owned U,S, p a t e n t  i s  be ing  forwarded f o r  
a b s t r a c t i n g  and announcement i n  NASA STAR. 
The following information i s  provided: 
U,S. Pa ten t  No. 3,281,965 
Corporate Source E F l i g h t  Research Center  
Supplementary 
Corporate Source 
NASA Pa ten t  C a s e  NO, :  XFR-04147 
Enclosure: 
copy of Pa ten t  
NASA-HQ 
https://ntrs.nasa.gov/search.jsp?R=19710001274 2020-03-17T02:34:52+00:00Z
K. s. IRWIN 
CONTROLLED VISIBILITY DEVICE FOR AN AIRCRAFT 
Filed Aug. 2, 1965 2 Sheets-Sheet 2 
72 
76 
78 
0t; 84 76 
P - BY 
u\ts.\u II, 
i 
K. S. IRWIN 
CONTROLLED VISIBILITY DEVICE FOR AN AIRCRAFT 
Filed Aug. 2, 1965 2 Sheets-Sheet 1 
62 
64 
22 
35 38 
1 NVENTOR. 
3,281,965 
$<irk 9. Irwin, Lsncaster, Calif., assignor to the United 
States of America as represented by the Admiaistratoh 
of the Nagonal Aeronautics and Space Administration 
Piled Bug. 2, 1965, $ere No. 476,761 
1 Claim, (Cl. 35-12) 
The invention described herein may be manufactured 
and used by or for the Government of the United States 
of America for governmental purposes without the pay- 
ment of any royalties thereon or therefor. 
This invention relates in general to flight training de- 
vi'ces for simulating flight conditions of poor or no visi- 
bility employed in training a pilot in instrument landing 
and flight procedures. More particularly, this invention 
is a controlled visibility window panel for an aircraft 
which makes it possible to vary the cockpit visibility from 
a condition of no visibility to a condition of good visibility 
in a gradual manner that closely approaches visibility 
conditions actually encountered by an aircraft breaking 
out from cloud cover in an instrument landing. 
Blind flight simulator devices used heretofore have 
been many and varied. Examples of these are: cockpit 
hoods which block the view 'of the pilot, special blue gog- 
gles used in combination with orange plastic window 
panels which result in near zero visibility for the pilot 
when he looks out the window, and blinders which block 
out the outside view of the pilot when the pilot looks at 
his instruments. 
These prior art devices have had the common diwd- 
vantage of allowing only instantaneous changes of visi- 
bility. In other words, they do not provide a realistic 
gradual breakout, but rather change instantaneously from 
the condition of no visibility to a condition of good visi- 
bility. In addition, with the use of these prior art devices, 
the removal of vsibility restriction on the pilot is general- 
ly accomplished by the pilot himself, thereby reducing 
the effectiveness d the simulation. Further, the psycho- 
logical effect of the pilot knowing that he can himself 
physically remove his visibility restriction at any time 
also (affects adversely the effectiveness of training when 
utilizing such devices. 
A controlled visibility panel or blind flight simulator 
device constructed in accordance with the principles of 
this invention avoids the disadvantages inherent in prior 
art devices. This is accomplished, briefly, by providing 
a controlled visibility panel member that is mounted over 
the cockpit windows such that it is positioned in the 
field of view of the pilot. The panel has a pair of open- 
ings formed therein, one directly in front of the pilot and 
one to the side of the pilot. These openings are each 
covered with la window or lens assembly that includes a 
pair of superimposed lenses oonstructed of a light polar- 
izing material such as glass, plastic, or other suitable 
material. These superimposed lenses are rotated relative 
to one another to control the amount of light transmitted 
through the lens assembly. A control apparatus, includ- 
ing an electric motor, driving gears, and a cable and pulley 
assembly are connected to one of the lenses for rotation 
thered so as to permit rapid and uniform selection of the 
visibility conditison desired. The other lens in each lens 
assembly is manually adjustable. Inasmuch as the theory 
and principle of how two or more superimposed lenses or 
windows composed af light polarizing material can be 
oriented with respect to one another to control the light 
transmitted therethrough is well known, it will not be 
discussed in any detail herein. Suffice it to say that by 
proper angular orientation or 'alignment of the two polar- 
izing lenses covering each opening in the panel, the pilot's 
visibility through the openings can be selected. The elec- 
tric motor, which controls the position of one of the 
polarizing lenses in each lens assembly, is controlled by 
the flight instructor so as to enable him to select, at will, 
It is, therefore, a principal object 'of this invention to 
provide a greatly improved blind flight simulator device 
capable of realistically simulating poor visibility Bight 
conditions. 
It is another object of this invention to  provide a blind 
flight simulator device wherein it is unnecessary to en- 
cumber the pilot with apparatus worn on his person. 
A yet further object of this invention is to provide a 
blind flight simulator device which m,akes it possible l o  
15 gradually change the pilot's visibility from a condition of 
no visibility to a breakout condition of good visibility. 
Yet another object of this invention is to provide a 
blind fight simulator device wherein the pilot has no con- 
trol over the visibility condition provided. 
Other objects and advantages of this invention will be- 
come more apparent when considering the following de- 
tailed description in conjunction with the attached draw- 
ings wherein: 
FIG. 1 is a broken away view d an aircraft and aircraft 
25 cabin in which a controlled visibility window panel has 
FIG. 2 is a view of one side of the controlled visibility 
FIG. 3 is a view similar to FIG. 2 with the polarizing 
FIG. 4 is a view of the forwardly facing side of the 
controlled visibility panel. 
FIG. 5 is a view, partially in section and broken away, 
taken 'along lines 5-5 of FIG. 4, that illustrates the de- 
35 tails of the control apparatus for rotating the polarizing 
lens in each lens assembly and also illustrates the detalis 
of how the polarizing lenses (are mounted in the panel 
member. 
FIG. 6 is a view taken along lines 6-6 of FIG. 4 which 
40 illustrates details of the control mechanism and the 
mounting of the polarizing lenses in the panel member. 
FIG. 7 is a broken away view of the driving connection 
between the electric motor mounted on the panel member 
and the control mechanisms attached to the polarizing 
FIG. 1 of the drawing illustrates an aircraft with a 
controlled visibility device 12 mounted behind windows 
14 of the cabin. The controlled visibility device con- 
sists of a panel member 16 in which two holes 18 and 20, 
50 see FIG. 2, have been provided. A pair of lens or win- 
dow assemblies, 22 and 24, are mounted to the panel so 
as to  cover openings 18 and 20. The panel member is 
positioned on one side of the aircarft cockpit directly be- 
hind the cockpit windows such that lens assembly 24 will 
55 be directly in front of the pilot's face, and the lens assem- 
bly 22 to  one side of the pilot's head. By this arrange- 
ment the pilot's view is effectively restricted to what can 
be seen through the lens assemblies. 
Lens assembly 24 consists of a pair of superimposed, 
60 transparent light polarizing lenses, 26 and 28, one of 
which, lens 26, is normally maintained in a fixed position 
while lens 28 is rotatably mounted with respect thereto. 
Lens 26 is mounted in annular frame member 30 with 
a gasket or seal 32 therebetween. Lens 24 and frame 
65 member 3Q are retained in place by an annular mounting 
bracket 34 attached lo panel 16, around the periphery of 
opening 18 by screws 35 or other suitable means. 
Mounting bracket 34 has an arcuate adjusting slot 36 
formed therein, see FIG. 2, which receives a stem portion 
of an adjusting stud 38. The adjusting stud screws into 
annular frame member 30. It is apparent from a con- 
5 a desired visibility condition. 
10 
20 
been installed in one side of the aircraft cabin. 
panel taken along lines 2-2 of FIG. 1. 
30 lens assemblies partially broken away. 
45 lenses. 
3,281,965 
sideration of FIGS. 2 and 5 that by merely loosening the 
stud 38 it is possible to rotate lens 26, within limits de- 
termined by the length of slot 36, reltaive to mounting 
bracket 34. When the panel is installed in an aircraft 
and in use, lens 26 is maintained in a fiied position and 
frame member 30 is held snug against mounting bracket 
34 by tightening the adjusting stud. Lens 28 is mounted 
in an annular frame member 40 with a gasket or seal 42’ 
disposed therebetween. Frame member 4Q is rotatably 
supported in opening I8 by means of four bearing assem- 
blies 42 which consist of a block 43 and a roller bearing 
44 mounted on a shaft 43’ that is journalled in block 43. 
Roller bearing 44 rides in slot 48 formed in the periphery 
of annular frame member 40. This arrangement sup- 
ports the frame member for rotation about its center and 
maintains the alignment of the frame member and lens 
28 with respect to opening I8 in panel 16. Bearing as- 
semblies 42 are suitably attached to panel 16 by bolts or 
other suitable means. A pair of T-shaped members, 50 
and 52, see FIG. 4, are mounted on the periphery of an- 
nular frame member 40. The function and operation 
of these T-shaped members will be described in detail 
hereinafter. 
Lens assembly 22, mounted in panel 16 is very similar 
to lens assembly 24 discusesd above and consists of a pair 
of superimposed lenses 54 and 56 which are mounted on 
panel 16 so as to cover opening 20 therein. Lens 54 is 
mounted in an annular frame member 58 with a seal or 
gasket 60 provided therebetween. The frame member 
is held in position by a mounting bracket 62 which has 
an arcuate slot 64 formed therein. An adjusting stud 66 
passes through the arcuate slot and screws into annular 
frame member 58 so as to permit adjustment of the an- 
gular position of lens 54 and also to secure the annular 
frame member and lens in a fixed position. Lens 56 is 
mounted in a rotatably mounted frame member 68 with 
a gasket or seal 70 provided therebetween. Frame mem- 
ber 68 is rotatably supported in opening 20 by four bear- 
ing assemblies 72 which are identical in structure and op- 
eration to bearing assemblies 42 discussed above. The 
roller bearings (not shown) included in bearing assem- 
blies 72 ride in groove 74 provided in frame member 68. 
Frame member 68 has an arcuate gear segment 76 at- 
tached thereto by bolts or other suitable means, and this 
gear segment engages a motor mechanism 78 shown in 
FIG. 7. 
Motor assembly 78 consists of a reversilble electric 
motor 80 mounted in panel 16. Output shaft 82 of 
motor 80 extends through panel E6 and engages a gear 
84 mounted for rotation on extension 86 of the electric 
motor housing. Gear 84 is in driving engagement with 
gear segment 76 and thus rotation of output shaft 82 is 
translated into rotation of lens 28 with respect to lens 26. 
A cable 88 rides in groove 89 formed in frame member 
48 and passes over a pulley assembly 90 mounted on 
panel 16 and is connected to T-shaped member 50. The 
other end of cable 88 passes over a pulley assembly 95 
mounted on panel 16 and connects to T-shaped member 
52. The T-shaped members are provided with grooves 
92 and 93 which receive cable 88. Thus, rotation of 
gear segment 76 rotates lens 28 and frame member 40 
and this rotation is translated to inner lens 56 and frame 
member 68 through the cable and pulley arrangement. 
(Cable $8 can either be in one piece and pinned to frame 
member 40 to prevent slippage, or in two pieces with each 
piece attached to the frame member. 
A pair of limit switches 96 and 98 are mounted on 
panel 16 in an appropriate position about the periphery 
of opening 20. Limit switches 96 and 98 are connected 
into motor assembly 78 by appropriate circuitry (not 
shown) so that when either of the limit switches are ac- 
tuated by T-shaped members 52 and 50, as will be more 
fully described in the discussion of operation hereinafter, 
ihe o2eration of electric motor 80 will be interrupted. 
This appropriate circuitry (not shown herein since it 
is state-of-the-art circuitry) includes suitable on-off 
switches which are controlled by the co-pilot or instruc- 
tor in the cockpit of the aircraft during any flight instruc- 
In operation, assuming the visibility panel is mounted 
in an aircraft in flight, the various components of the 
visibility panel are in a position illustrated in FIG. 4 
wherein the pilot has good visibility through both lens 
10 assemblies. When it is desired to simulate blind flying 
conditions, the flight instructor will flip a switch to ac- 
tuate motor 80 and thus rotate gear segment 76 and an- 
nular frame member 40 in a counterclockwise direction. 
This will rotate lens 28 to a position where no light is 
15 transmitted through lens assembly 24. Rotational mo- 
tion of lens assembly 24 is translated through cable 88 
to lens assembly 22. When lens assembly 22 has been 
rotated to a position wherein T-shaped member 52, as 
shown in dotted lines in FIG. 4, engages limit switch 96, 
20 the operation of the reversible electric motor 80 will be 
interrupted. At this point the pilot #being trained is un- 
able to see through lens assemblies 22 and 24 and the 
training in instrument landings and/or instrument flight 
can begin. Assuming that an instrument landing is to be 
25 practiced wherek the normal conditions encountered are 
a condition of no visibility at a certain altitude, with a 
gradual breakout to a condition of good visibility at a 
relatively low altitude, the pilot would begin his land- 
ing approach relying on instruments alone. At a certain 
30 preselected altitude or  time the flight instructor would 
flip a switch actuating electric motor 80 so as to cause 
gear segment 76 and annular frame member 40 to be 
rotated in a clockwise direction. This should result in 
rotation of lens 28 and also lens 56 in lens assembly 22 
35 to a position wherein the pilot has good visibility through 
the two lens assemblies. When a condition of maximum 
visibility has been obtained the T-shaped member 58 will 
engage limit switch 98 to interrupt the operation of re- 
versible electric motor 80. 
The length of time required for the lens assemblies to 
be rotated from a condition of no visibility to good visi- 
bility is, as is believed readily apparent, controlled by 
the speed of electric motor 80. Inasmuch as the change 
in visibility conditions normally encountered is somewhat 
45 gradual, it is usually desirable in order to  achieve realism 
to rotate the lenses relatively slowly so as to gradually 
change from a condition of no visibility to a condition 
of good visibility. In the event that it should become 
desirable or necessary to suddenly change to a condition 
50 of good visibility, the flight instructor can grasp the ad- 
and 66 and manually turn the outer lenses 
26 and 54 to a position where the pilot can see through 
the lens assemblies. 
This completes the detailed description of this inven- 
55 tion, and while a preferred exemplary embodiment has 
been described herein, it will be obvious to one skilled 
in the art to which this invention pertains, that many 
changes and modifications thereto can be made without 
departing from the spirit and scope of the invention as 
60 defined in the claims appended hereto. 
6 tion. 
40 
What I claim is: 
A controlled visibility device for mounting in an air- 
craft cabin so as to control the visibility of a pilot operat- 
ing the aircraft and thereby realistically simulate blind 
6.5 flying conditions, said visibility device comprising: 
(a) a panel removably mounted over the cabin window 
of the aircraft; 
(b) said panel having a first circular opening directly 
in front of the pilot, and a second circular opening 
at one side of the pilot; 
(c) a first pair of superimposed discs of light polariz- 
ing material covering the first opening in said panel 
and a second pair of superimposed discs of light 
polarizing material covering the second opening in 
70 
75 said panel; 
3,281,065 
5 
(d) one of the discs in each pair of discs being 
mounted on said panel in a normally fixed position 
whereas the other disc in each pair is rotatably 
mounted on said panel; 
(e) servo means mounted on the panel and connected 
to the rotatably mounted discs for rotating them in 
unison to  continuously and selectively vary the visi- 
bility through said first and second pairs of super- 
imposed discs from none to good visibility; said servo 
means including: 
(1) a first annular frame member in which the 
rotatably mounted disc of superimposed discs 
is mounted, said frame member being supported 
for rotation by a plurality of roller bearing as- 
semblies mounted to said panel around the pe- 
riphery of the first opening in said panel; 
(2) a second annular frame member in which the 
rotatably mounted disc of said second pair of 
superimposed discs is mounted, said frame mem- 
ber being supported for rotation by a plurality 
of roller bearing assemblies mounted to said 
panel around the periphery of the second open- 
ing in said panel; 
(3) an electric motor mounted on said panel, 
(4) mechanical means connected between said 
electric motor and said first tand second frame 
members for rotation thereof by said electric 
motor; said mechanical means including: 
(i) a pair of T-shaped members mounted in 
a spaced relation on said first annular frame 
member; 
(ii) a gear segment mounted on said second 
annular frame member, said gear segment 
being in driving connection with said elec- 
tric motor; 
(iii) a first cable connected between one of 
said pair of T-shaped members and one 
end of said gear segment, and 
a second cable connected between the 
other one of said pair of T-shaped mem- 
bers and the other end of said gear seg- 
ment, whereby rotation of said second an- 
nular frame member by said electric motor 
and said gear segment, in either a clock- 
wise or counterclockwise direction, will be 
translated to said first annular frame mem- 
ber through said first and second cables and 
said pair of T-shaped members. 
References Cited by the Examiner 
UNITED STATES PATENTS 
1,833,970 12/1931 Levick _ _ _ _ _ _ _ _ _ _ _ _ - _ _  35-12 
2o 2,090,132 8/1937 Lacoe _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  35-12 
2,368,117 1/1945 Damian _ _ _ _ _ _ _ _ _ _ _ _ _ _  8 8 4 1  
2,417,317 3/1947 McMains _ _ _ _ _ _ _ _ _ _  35-12 X 
2,440,274 4/1948 Ibisch _ _ _ _ _ _ _ _ _ _ _ _ _  35-12 X 
25 2,492,969 1/1950 Crane _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  35-12 
2,842,868 7/19-58 Belter _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  35-12 
3,001,300 9/1961 Green _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  35-12' 
30 3,015,988 1/1962 Hemstriet _ _ _ _ _ _ _ _ _ _  35-12 X 
5 
(iv) 
10 
15 
2,403,195 7/1946 ROSS _--______-____ 35-12 X 
2,510,848 6/1950 Wood _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  35-12 
EUGENE R. CAPOZIO, Primary Examiner. 
S. M. BENDER, Assistant Examiner. 


Controlled visibility device for an aircraft Patent

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