Jan. 31, 1950
w. c. scHRox-:DER y
2,495,777
PILOTAGE COMPUTER
Filed July 12, 1946
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Patented Jan. 31, 1950
'2,495,777
UNITED STATES l' PATENT oFFicE
2,495,777
PILOTAGE CQMPUTER
william o. schroeder, United states Army,
Hackettstown, N. J.
Application July'lZ, 1946, Serial No. 683,196
l
3 Claims.; (Cl. 235-61)
(Granted under the act of March 3, 1883, as
amended April 30, 1928; 370 O. G. 757)
The invention described herein may be manu
factured and used by or for the Government for
governmental purposes, without the payment to
me of any royalty thereon.
This invention relates to navigation instru
ments, and may be designated a pilotage com
puter.
` An object of the invention is to provide a navi
gation instrument adapted to be used in conjunc
2
portional to the scale of the sectional map with
which the instrument is designed to be used. The
scale I2 which may be colored a distinctive color
such as red to readily distinguish it from the scale
II which is preferably colored black, may be in
statute miles, but on the same proportional scale
as the scale I I. Along the shorter marginal edges
of the panel there are speed scales constituting
the ordnance of time-speed-distance graph that
tion with sectional maps wherein the meridians 10 is on the panel. The speed scale indicated at I2
are all disposed parallel to each other and verti
may be in knots and its opposed speed scale I3
cally arranged on the map. Maps of this charac
may be in miles per hour. As most airplane
ter are conventional and are used by navigators
speeds are from 100 to 200 knots only that portion
on aircraft.
of the speed scale from 100 to 200 knots is ap
More specifically, an object of the invention is
plied to the panel. However, it will be appre
to provide a navigation instrument consisting of
ciated that the invention is in no way restricted
a section or panel of transparent material which
to the use of such a shortened speed scale. The
may be positioned on the map and the map read
speed scale I3 in miles per hour is in direct pro
therethrough and which has on the panel one or
portion to the speed scale I 2 in knots. Horizontal
more distance scales and one or more speed scales 20 lines I4 are drawn across the panel opposite units
arranged at right angles to the distance scales,
on the speed scale and constitute speed lines.
the speed scales having lines extending across the
Time lines I5 which are of progressively decreas
panel parallel to the distance scale and being trav
ing inclination from left to right across the panel
ersed by time lines that cross the speed lines at
are drawn across the speed lines so as to trav
points equal to or proportional to distances as -' erse them at points equal to or directly propor
measured on the distance scale per units of time.
tional to the distances travelled per units of time
A slide is movable across the panel at right angles
as measured by the distance scale. Thus for ex
to the distance scales and has speeds graduated
ample, the time line I 5 indicating `an elapsed
thereon and superimposed upon the panel is a
time of ñve minutes traverses the speed line of 180
protractor or portion thereof the center of which
knots vertically above the 15 graduation on the
is indicated. With an instrument so constructed
>scale II to indicate that at a speed of 180 knots
most, if not all, of the normal navigator’s pilotage
the aircraft will have traversed fifteen nautical
calculations can be quickly solved in applying
miles in ñve minutes. This same time line trav
the instrument to a conventional sectional map.
erses the speed line of 120 knots vertically above
With the foregoing and other objects in view, “ the 10 graduation on the distance scale I I to in
which will be made manifest in the following de
dicate that at a speed of 120 knots ten nautical
tailed description and speciiically pointed out in
miles will have been traversed in five minutes.
the appended claims, reference is had to the ac
In a similar manner the time line I5 indicating
companying drawings for an illustrative embodi
twenty minutes of' elapsed time traverses the
40 speedline 180 knots vertically above the 50 grad
ment of the invention, wherein:
Figure 1 is a top plan View of the improved
uation on the distance scale II to indicate that
pilotage computer embodying the present inven
at a speed of 180 knots the aircraft will have
tion; and
traversed a distance of sixty nautical miles.
Figure 2 is a sectional view taken substantial
Similarly, this same time line traverses the speed
ly upon the line 2-2 upon Fig. 1.
line 120 vertically above graduation 40 on the dis
Referring to the accompanying drawings
tance scale II to indicate that at a speed of 120
wherein similar reference characters designate
knots the aircraft will have travelled forty nau
similar parts throughout, the improved naviga
tical miles in twenty minutes. All of the various
tional instrument consists of a flat panel I 0 of
time lines I5 which are thus drawn will traverse
transparent material such as Plexiglas. This 50 the speed line I 4 at points directly proportional
panel is rectangular in form and along its longer
edges it preferably is equipped with distance
scales II and I2.
g
In the preferred form of construction the scale
and preferably equal to distances traversed per
their respective units of time at the speeds in
dicated.
.
A slide I6 is provided which is likewise formed
,-_I Ils in nautical miles equal to? or .directly-pro- 55 of transparent material and this slide is provided
2,495,777
3
with recesses I'I and I8 which receive the edges
of the panel enabling the slide to be moved hori
zontally across the panel I0. This slide presents
edges I9 and 2€) that are parallel to each other
and which are at right angles to the longer edges
of the panel. Along the ed‘g'e I9 there is a speed
scale 2l that `may be ñnely 'graduated on the
same scale as the speed scale I2 and along the
edge 20 there is a finely graduated speed scale
equal to the speed scale I3. The two speed scales 10
on the slide being thus in knots and in miles per
hour are preferably colored blackrand red, re
spectively, to readily distinguish them. superim
posed on the panel is a protractor 22 the center
of which is indicated at 23. Preferably the center
4
ing the slide against the distance scale II. The
distance of ñfty miles is then laid out from the
point of departure along the true heading drawn
on the map and the wind vector is drawn from
such point to the point C. This wind vector may
have its direction determined from the protractor
and its fspeed >determined from the 4distance scale
used to measure the length of the vector. The
correction from the point C to the point B may
then be made by using the protractor and by
sighting along the computer at the previous
vground speed determined to be 164 knots, a time
~to the destination may be readily read.
The above problem is merely illustrative of one
`manner in which the improved computer may be
used. The ability however to instantly read from
the graph distance from speed and elapsed time
foration through the panel. While only a half
or time `from speed and distance greatly facilitates
of a compass rose is used as the protractor in the
the solution of many navigational problems.
construction illustrated it is within the scope `oiî
Various changes may be made in the details
the invention to use a `complete compass rose if 20
of construction `without departing from the spirit
desired.
l
'and scope of the invention 'as defined by the ap
The uses of such a navigational instrument will
of the protractor is in the nature of a small »per
‘be‘readily understood byfskilled-nagivators. How
:eveigas illustrative of the :manner in which sim
ple navigational problems may be solved therewith
:the yfollowing explanation may be made: It will,
of course, be appreciated 'that it is possible to
linstantly convert nauticalmiles intostatute miles
by positioning the slide opposite a graduation on
the scale fI l and'reading'the corresponding statute
pended claims.
I claim:
l. A navigational instrument comprising a
.panel Aor" transparent material having lon two’op
posite edges distance scales in nautical miles and
statute miles respectively rand having on 'the
,other two opposite edges thereof scales in speeds
in knots and in miles-per-hour respectively,
parallel speed lines between said last named
miles directly on the scale I2. Similarly, it is pos
ledges and time lines traversing the speed linesfat
sible to instantly convert speeds in knots into
points indicative of the distance traveled per units
:speeds in miles per hour by reading across the
of time as indicated by the distance scales, a pro
-panel from scale I2 to scale I3.
VSuppose .thata flight is to be taken Írom'a point 35 tractor on the panel having its center indicated
thereon, and a slide movable over the panel vhav
oi departure on a sectionalmap to a. given desti
nation, 'that iis Ifrom point A, the point of de
ing speeds in knots and miles-per-hour graduated
thereon.
2. A navigational instrument comprising Aa sub
parture, Yto point B, the destination. Any con
venient speed line I4 is alignedalong the'intended
course from A to B and the panel moved over 40 stantially rectangular vpanel of transparent ma»
terial having parallel speed lines extending there
the map until the perforation ’23 is over a merid
-across >and Vterminating short of both side »edges
ian. rEhe course angle from A to B may be in
.of the panel, there being speed in knots scale on
stantly read off of .the protractor '22. 'Using either
'one side edge of the panel yhaving numerals reg
of the distance scales II or I2, the -distance be
istering with the parallel lines, there being a
145
tween A and B .may be instantly determined
speed in Amiles per hour scale on the »opposite
either in nautical miles Yor statute miles as de
side edge having numerals registering with the
sired. ïi, for example, `the course angle from A
'parallel
lines, the top and bottom edges of the
to B was lread on the protractor 22 as being 43°
'panel having scales in statute miles and nautical
and the direction and the velocity of the wind
miles, respectively, time lines traversing the
are unknown the pilot vmay »be given a magnetic
Vspeed
lines at points indicative of the distance
'heading of 36°. The progress of the airplane is
traveled per units of time as indicated `by the
followed ralong the sectional, along the air speed
distance scales, there being time scales having
-line ci the plane which may be 150 knots. Sup
numerals in registry »with at least some of the
pose that in twenty minutes the Vairplane passes
over a point C somewhat off ofthe straight line 55 time lines and located adjacent the top and bot
tom edges of >the panel, 'and a slider having side
joining A and B, the panel Il) is then positioned
vedges extending vertically completely across the
on the map in such a manner that the beginning
panel, the slider having end .portions extending
oí the speed line 150 knots is over point A and
.over and behind the panel for guiding the ‘slider
the line joins A and C'. The slide I6 is then posi
tioned to point C. The twenty minute line is 60 across the panel, one 4vertical edge of the slider
'having a scale in miles per hour, the last named
then followed up to the point where it passes be
scale having numerals out of registry with the
neath the slide’and may show a ground speed rate
parallel speed lines, the opposite Vertical edge Aof
von _the scale ‘ZI of 164 knots. .Off the distance
the slider having a scale in knots registering with
scale i i on the bottom of the panelthe slide may
the parallel speed lines.
indicate a distance of 541/2 nautical -miles from
3. A navigational instrument comprising a sub
A to C. By sliding the `panel so that the center
stantially rectangular panel of transparent ma
23 to a meridian the “track made good” of 49°
terial having parallel Yspeed lines extending there
on the protractor may be read.
'across and terminating short of both side edges
To iind a wind the theoretical >heading of 43°
of the panel, there being speed in ‘knots scale on
may be drawn on the sectional inap and using
`one Aside edge Íof the panel having numerals reg
the pilotage computer the elapsed time of twenty
istering with the parallel lines, there ïbeing a
minutes of true air speed _may be'read Aas being
speed in miles per hour scale on the opposite side
nity miles by positioning the edge of the .slide
vedge having numerals `registering with the `paral
`opposite the >point where the Atwenty-minute time
„line traverses the 115,0 „knots speed linegndlead. ’ 715 lel lines, 'the top and‘bottom edges .o'f the panel
5
2,495,177
6
having scale in statute miles and nautical miles,
respectively, time lines traversing the speed
REFERENCES CITED
lines at points indicative of the distance trav
eled per units of time as indicated by the dis
tance scales, there being time scales having nu
merals in registry with at least some of the time
The following references are of record in the
file of this patent:
lines and located adjacent the top and bottom
edges of the panel, a slider having side edges ex
tending vertically completely across the panel,
Number
the slider having end portions extending over w
and behind the panel for guiding the slider
across the panel, one vertical edge of the slider
having a scale in miles per hour, the last named
scale having numerals out of registry with the
parallel speed lines, the opposite vertical edge of
UNITED STATES PATENTS
1,930,478
1,935,907
2,179,531
2,219,429
Name
Date
Jones ___________ __ Oct. 17,
Weems ___________ „_ Jan. 1,
Trapnell ________ __ Nov. 14,
Costerberg ______ __ Oct. 29,
OTHER REFERENCES
1933
1935
1939
1940
_
“Graphical Charts,” by John B. Peddle, pub
lished by McGraw-Hill Book Co., Inc., 239 W. 39th
the slider having a scale in knots registering with l5 st., N. Y., in 1919. ' (Copy on me in the Patent
Ofñce Library.)
the parallel speed lines, and a protractor on the
panel having its center indicated thereon.
WILLIAM C. SCHROEDER.