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Патент USA US2404978

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July 30, 1946.
E. o. MoRToN
2,404,978
FLUID SPEED‘ INDICATOR
Filed Feb. l0, 1944
.lu
/ /7
ATTORNEY
Patented July 30, 1946
2,404,978
UNITED STATES PATENT OFFICE
2,404,978
FLUID SPEED INDICATOR
Eldred O. Morton, Mansñeld, Ohio, assignor to
Westinghouse Electric Corporation, East Pitts
burgh, Pa., a corporation of Pennsylvania
l
Application February 10, 1944-, Serial No. 521,815
13 Claims. (Cl. 73--212)
My invention relates t0 devices for indicating
the speed of a craft with reference to the medium
through which it moves and more particularly
to Pitot-static tubes, static tubes, and Pitot tubes.
My invention has particular utility for indi
cating the air speed of an aircraft by means of
the measurement of the static air pressure, the
dynamic air pressure, and the measurement of
the relative dynamic and static pressures. My
invention is, however, not limited to this par
ticular application but is applicable to any ap
plication where static and dynamic fluid pres
sures are to be measured.
As is well known, tubes of this type are
2
One object of my invention is the prevention
of the collection of any obstructing moisture
Whether in the form of ice or in the form of
liquid in the chambers, conduits and openings
in elements of Pitot-static tubes, static tubes,
and Pitot tubes.
Another object of my invention is the provision
of means for heating a Pitot-static tube by means
that may be readily manufactured
assembled and by means of which
properly distributed so that moisture
of ice or otherwise that may collect
and readily
the heat is
in the form
in the tube
is readily and continuously discharged from the
tube.
mounted on the outer portion of an aircraft 15
A still further object of my invention is the
Wing, outboard strut or other location of an air
provision of an improved tube construction for
craft Where the tube openings will be exposed to
air-speed indicators.
air flow in a region substantially undisturbed
An important object of my invention is to
by the craft itself. By means of suitable pipes
simplify the construction and assembly and re
the tube openings are connected to an instru 20
duce the cost of the heater unit for an electrically
ment on the instrument panel. The dynamic
heated air-speed tube.
pressure is usually communicated to the interior
It is also a broad object of my invention to
of a hermetically sealed chamber having a mov
provide
an electrically heated Pitot-static tube
able diaphragm in one Wall thereof for operating
an indicator, and the static pressure is com
municated to the outside of the chamber to exert
a pressure on the diaphragm in opposition to the
dynamic pressure effect. The differential pres
sure effect is thus indicated by the instrument
of simple structure and having elements that
may be easily and cheaply assembled and that
may have improved operating characteristics.
Other objects and advantages Will become more
apparent from a study of the following speci
iication and the accompanying drawing, in
thus indicating', or recording, as may be desired, . 30 which:
the speed of the fluid relative to the Pitot-static
tube. With other instruments the two pres
sures are communicated to two Bourdon tubes
Figure 1 is a longitudinal sectional View of
the housing portion of a Pitot-static tube with
certain parts broken away to illustrate some
coupled mechanically at their movable ends in
details;
opposition, or communicated to two Sylphcn 35 Fig. 2 is a longitudinal sectional view sub
bellows constructed like the Sylphon bellows of
stantially normal to the section plane of Fig.
aneroid barometers, which Sylphon bellows are
1; and
also mechanically coupled in opposition at their
Figs. 3, 4, 5 and 6 are transverse sectional
movable portions to thus produce indications
views
on section lines III-,111, IV-IV, V--V,
proportional to the pressure differences in the 40 and VI-VL
respectively, of Fig. 2.
two pressure responsive members. To make the
So far as the outer contour of my improved
instrument particularly useful to the pilot, the
Pitot-static tube is concerned, it is conventional
calibration is usually in miles per hour.
in shape, that is, it has an outer cylindrical tube
Since the Pitot-static tube must necessarily
or casing I provided with a tapered forward
be located in the undisturbed region 0f the air,
end 2. The casing is preferably made of sheet
it is exposed to all climatic conditions and thus
or extruded brass, copper, or some other metal
is particularly subject to the temperature of the
or alloy having good heat conducting «properties
surrounding air and the moisture content there
and being resistant to corrosion. Since ' this
of. The introduction of moisture into the Pitot
sheet
material is easily formed, the tapered end
static tube at the low temperatures usually en
2 may be formed by spinning.
countered by aircraft at certain seasons and at `
high altitudes causes the moisture to freeze in
the tube and thus impair, and more usually com
pletely nullify, the operation of the air-speed
indicating instruments.
At the right-hand end, or rear end, the tube
lents a machined portion of the brass or copper
casting 3 and is secured to the casting by solder
ing or brazing or in some other suitable man
ner. The casting has a machined cylindrical
9,404,978
d.
The sleeve 32 is disposed into a longitudinal
opening, or well, in plug El so that the front
closure 33 is substantially flush with the front
projecting portion ß threaded, as shown in Fig.
2, for receiving the bolts -5 (usually four) pro
viding the rigid interconnection between the
casting 3 and the cylindrical bracket 6 which
is rigidly mounted on some suitable portion of
the aircraft. The point of connection of the
Pitot-static tube is so selected that it is rigidly
supported to point in the direction the aircraft
ig pointing and at a region of air ñow substan
tially undisturbed by the craft itself.
end of plug 2l and the plug 2S, also having a lon
gitudinal opening, is disposed over the rear end
of the sleeve 32 so that the closure
falls some~
what short of the right-hand, or the bottom, of
the well in the plug Z8.
The disk 33, together with the plug 2l, forms
10 a hermetic seal between chamber 26 and the porn
tion to the right of the region of brazing 29. The
only passage of ñuid pressure from chamber 25
The casting, or end member 3, has a trans
verse wall 'i provided with a pair of apertures
3 and S, as shown in Fig. 1, for receiving the
conductors l@ and ll leading to the heater unit
l2 described more in detail hereinafter.
toward the right is thus through tube 35 to be
described hereinafter. The closure 34 is also her
15 metically sealed to the plus 2S
The conductors l@ and ll are suitably con»
nected to the connector studs I3 and M within
porcelain ferrules shown, and the parts are held
in ñrm relation to the wall 'l by nuts l5 and
l5 for driving the porcelain ferrules against the
relatively soft mica Washers disposed at the left
of the porcelain ferrules, all as shown.
The wall 'l is also provided with two further
apertures ll and i8 for receiving, through seals
23 and 2.6i, the outlet tubes i9 and 20 for the
dynamic and static pressures, respectively.
These tubes are connected, by means of pipe con
nections 2l and 22, to another pair of tubes
(not shown) leading to the air-speed indicating
instrument (not shown).
At the nose or left-hand end of casing l, I pro
vide an opening 25 for receiving the dynamic air
pressure and communicating that pressure to the
region, or chamber, 26.
Two plug members, or heat distributing blocks, ï
2l and 28 are mounted within the casing l. The
blocks, when the assembly is complete, are rigidll7
held in place by soldering or brazing, preferably
brazing, at regions 29 and 3U. The plug members
are preferably composed of copper, or some other
corrosion resistant metal having good heat con
ducting properties.
The electrical heating unit includes a tube 3l
of relatively rigid insulating material upon which
the electric heating conductor or wire 36 is wound.
One end of this wire 35 is inserted from the front
of the tube through the relatively small axial
opening in tube 3l and, where projecting from
the tube 3l at the right end, is electrically con
nected to conductor ll. The portion of the wire
:it not inserted into the tube 3l is wound back
wardly from the front end of the tube 3l with
many relatively closely spaced turns. The closely
spaced turns encompass the tube 3l for a length,
measured from the iront end of the tube, corre
sponding substantially to the length of block 2l.
From the foregoing, it is thus apparent that for
the entire length of blocks Él’ and 28 the wire is
wound with many turns, but the number of turns
for the region of block 2.8 may actually be only
half that of the turns in the region of block 2l.
The reason for this distribution of turns is that
the heat dissipation is greater at the region of
block 2l than at the region of block 28. The num- \
ber of turns must, therefore, be greater than at
the region of block 28. By suitably proportioning
the relation of the number of turns, a heat dis
tribution is obtained that is in accordance with
the requirements of actual usage and yet the heat
is not wastefully dissipated.
The arrangement of the heater as a single car
tridge with suitable heat concentration at the
front and rear simplifies the construction and
the assembly extremely and reduces the cost of
the unit to a fraction of that of a heater built up
of a plurality of small cartridges. Further, the
sleeve 32, with the heating wire in position, can
for convenience of assembly, be slipped into the
blocks and secured to the blocks in proper spaced
relation as a unit and then this unit inserted into
the casing l from the rear.
The plug 21 has a substantially circular sec
tional shape Whereas the plug 28 has a sectional
shape as best shown in Fig. 4. Both plugs 2l and
2B are provided with longitudinal openings at the
45 bottom, or lower portions, for receiving the tube
35. The tube 35 within chamber 26 is curved uP
wardly and pinched together as shown at 3l and
is then provided with elongated or round side
openings 38 as shown.
50
The air entering the casing at opening 25 is
under dynamic pressure but may also be subject
to some turbulence. The turbulence, since the
openings 38 are at the side of the tube 35, can
not iniluence the dynamic pressure within the
55 tube 35. The pressure within the tube 35 is thus
a true indication of the dynamic pressure of the
air.
Near the middle of the tube 3 l, the number of
In order that no moisture may collect or ice be
turns is reduced and the spacing of the turns is
formed in chamber, I provide two or more aper
increased up to a point spaced from the right
tures 39 and 40 in the casing adjacent the tube
hand end of tube corresponding to the length of 60 35 and just to the left of the plug 2l. When the
block 2B. For the remaining length of tube 3l.
heater is electrically energized, any moisture that
the winding is such that the spacing of the turns
may enter the chamber 2G is maintained in a
is again decreased, that is, the number of turns
fluid state by the heat conducted to the plug and
per unit length is increased. The number of 65 to the casing. By the flow of air just outside of
turns per unit length for this region can, how
the casing and by natural drainage, the moisture
ever, be Iconsiderably less than the number of
is thus drawn out of chamber 26. The air in the
turns per unit length at the front end of the tube.
chamber 2E thus remains relatively warm and
The ratio of the number of turns per unit length
substantially quiescent regardless of the weather
at the respective ends of the tube 3l may be in the
conditions just outside. Perfect quiescence is, of
order of 2:1. At the right end of tube 3 l, the wire
course, not obtained because theoretically there is
35 is electrically connected to the conductor lll.
some slight air flow inwardly at opening 25 and
The tube 3l with the electric heating wire 3S
outwardly at openings 39 and t0. The curved
is inserted into sleeve 3.2. This sleeve is made
shape of tube 35 within the chamber 26 and the
of material having good heat conducting proper
arrangement 0f the apertures 38 make for a sub
ties. This sleeve 32 has closure disks 3% and 34.
2,404,978
5
6
stantially perfect quiescent state of the air with
stood that the disclosure is only illustrative and
in tube 35 and the transmission of the dynamic
air pressure to the instrument is at no time im
not exhaustive and that numerous changes in
paired.
.
The plug 28 has a vertical channel 4| that is
in communication with the longitudinal opening
42 so that the dynamic air pressure from tube 35
is transmitted to the lefthand end of tube I9.
details and combination and arrangements of
parts may be made without departing from the
spirit and the scope of my invention as'herein
after claimed.
I claim as my invention:
1. A Pitot-static tube comprising, in combina
tion, an elongated casing pointed at the front end
The tube 35 is brazed into plug 21, and, for a
short distance at the left of plug 28, into plug 10 having an opening at the front for receiving the
dynamic pressure of the fluid flowing with refer
28 in such manner that there is no leakage of any
fluid from chamber `26 to chamber 43, nor from
chamber 43 to channel 42.
To facilitate the manufacture of plug 28 and
ence to the Pitot-static tube, a front plug and a
rear plug within the casing and a rear closure
for the casing, said plugs and closure dividing the
the assembly of my Pitot-static tube, I out the 15 casing into a front chamber, a middle chamber
vertical channel 4l all the way through at the
and a rear chamber, said front plug being pro
bottom at 3D. When the heating unit and the
vided with a longitudinal channel at the top and
a second longitudinal channel at the bottom, said
plugs and tube 35, assembled as one construction,
rear plug being provided with a longitudinally
are inserted to correct position in casing I and
while being held in correct position, I i’irst braze 20 disposed Well at the top of a given depth, and
or solder the front plug 21 to the casing from the
being provided with a second longitudinally dis
opening 25. The relatively small hole 44, when
posed well at the bottom of the plug, a single
in registry with the vertical channel 4|, indi
elongated electrical heating unit in the upper
cates when the parts, or elements, within the cas
channel of the front plug and the upper Well of
ing are in correct position. After the front plug
the rear plug, a conduit passing through the bot
is brazed in position, which is a relatively easy
tom channel of the front plug and extending into
matter since opening 25 is not too small, I allow
the bottom well of the rear plug, said conduit
suiîicient brazing material to flow in at opening
ñtting snugly and sealed into said plugs so that
44 so that it wets the rear end of plug 28 and
when said electrical heating unit is in place there
leaves a closure, as shown at 30, for the bottom 30 be no communication between the ñrst and sec
of vertical channel 4l. All the parts are thus
ond chambers and the second chamber and the
brought into ñxed relation.
bottom well of the rear plug, a vertical channel
The foregoing method of assembly is the sim
at the rear end of the rear plug providing a
plest, cheapest and most expeditious, so far as
communication between the bottom well of the
known to me, ever utilized in the manufacture
rear plug and the top well of the rear plug, a
of Pitot-static, static and Pitot tubes, or similar
conduit extending through the top portion of the
rear plug into the vertical channel, a baille at
equipment.
the lower- forward end of said second mentioned
conduit, said second mentioned conduit provid
drilling through the closing plug at 30 to thus 40 ing a communication to an indicating instru
ment, said casing being provided with drain
provide a small opening from channel 4I to the
means near the front end of the front plug to
outside. This small opening provides an addi
tional safeguard that no obstructing moisture
drain out any moisture that might collect in the
Since the brazing material, or solder, will also
close the small hole 44, I again open this hole by
gets into tube I9.
Further, the left-hand end
of tube i9 extending into plug 2t, is provided `
with the arcuate protruding baffle 45. Should
the air, in spite of the front heating turns and
plug 21 and the apertures 39 and 4i). still contain
some moisture then the right-hand heating turns
front chamber, said casing and rear plug being
provided with drain means at the rear end of the
rear plug which drain means are in communica
tion with the Vertical channel in the rear plug,
said casing also being provided with a plurality
Aof openings in the top and bottom thereof near
heating the heat-conducting plug 28 will assure the front end of the rear plug to receive the
static pressure of the fluid flowing with reference
that the last remnants of moisture are expelled
at the small opening 44. The dynamic pressure
to the Pitot-static tube, said rear plug having
channels for providing a substantially free com
' communication to the air-speed indicating in
strument thus can not become clogged.
munication between the middle chamber and the
rear chamber, a conduit disposed in the closure
In order to transmit the static air pressure to
for providing a communication of the static pres
the tube 20, I provide the casing I with a plurality
sure from the rear chamber to an indicating in
of apertures 46 at the top and a similar group
strument.
of apertures 41 at the bottom. These apertures
are disposed just to the left of plug 28 and are
2. In a Pitot-Static tube, in combination, an
elongated casing having an opening in its forward
thus between the heated plugs 21 and 28. Any
end for receiving air under dynamic pressure,
moisture that may get into the chamber 43 when
and having an opening in its side for receiving
the heater is electrically energized is thus heated,
air under static pressure, a single electrical heat
the apertures 46 and 41 are kept free of ice and
ing unit, a pair of plug members embracing the
the air flow outside of the tube and natural
ends of said heating unit disposed in spaced rela
drainage remove the moisture from chamber 43.
tion Within the casing and fitting snugly and in
Since plug 28 is shaped as shown in Figs. 4
sealing relation against the inner Wall of said
and 5 forming the side channels 48 and 49, the
static air pressure in chamber 43 is thus trans
casing, the front plug member having a longitu
mitted to chamber 50. Since tube 20 opens into
dinal conduit disposed below the front end of
the heating unit and the second plug having a
chamber 50, the static air pressure is transmitted
from chamber 43 through channels 48 and 49,
longitudinal channel at vthe bottom thereof, a
dynamic pressure carrying conduit Iitting into
chamber 50 and tube 20 to the air-speed indi
cating instrument.
the top portion of the rear plug, said rear plug
AAlthough I have described my invention with
being provided with channel means for provid
reference to but one embodiment, it is under
ing an intercommunication between the channel
2,404,978
8
in the bottom of thel rear plug and said conduit,
interconnecting conduit means providing a com
munication duct from the region in front of the
second chamber and the bottom well of the rear
plug, a vertical channel at the rear end of the
rear plug providing a communication between
`the botto-m well of the rear plug and the top
front plug through the longitudinal conduit of
the front plug and the channel of the Second Ul portion of the rear end of the rear plug, a second
dynamic pressure transmitting conduit extend
plug to the dynamic pressure carrying conduit,
ing through the top portion of the rear plug into
said rear plug having additional channels eX
the vertical channel for transmitting the dynamic
tending entirely therethrough longitudinally to
pressure of the iiuid flowing past the casing to an
provide a free communication between the region
to the front of the rear plug land the rear of the 10 indicating instrument.
5. A Pitot-static tube comprising, in combina
rear plug, a static pressure conduit communicat
tion, an elongated casing pointed at the front end
ing with a region to the rear of the rear plug for
connection to an indicating instrument.
3. In a Pitot-static tube, in combination, an
elongated Casing having an opening in its for
having an opening at the front for receiving the
dynamic pressure of the iiuid flowing with refer
15 ence to the Pitot-static tube, a front plug and a
rear plug within the casing and a rear closure
for the casing, said plugs and closure dividing the
sure, and having an opening in its side for receiv
casing into a front chamber, a middle chamber
ing air under static pressure, a single electrical
and a rear chamber, said front plug being pro
heating unit designed to produce a greater heat
vided with a longitudinal channel at the top and
ing effect at `the front end than at the rear end,
a second longitudinal channel at the bottom, said
a pair of plug members embracing the ends of
rear plug being provided with a longitudinally
said heating unit disposed within the casing and
dispo-sed well at the top of a given depth, and be
ñtting snugly against the inner wall of said cas
ing provided with a second longitudinally dis
ing, the front plug member having a longitudinal
conduit disposed below the front end of the heat 25 posed well at the bottom of the plug, a single
elongated electrical heating unit in the upper
ing unit and the second plug having a longitudi
channel of the front plug and the upper well of
nel channel at the bottom thereof, a dynamic
the rear plug, said single elongated electrical
pressure carrying conduit ñtting into the top por
heating unit having more heating sections in the
tion of the rear plug, said rear plug being pro
vided with channel means for providing an inter 30 channel of the front plug than in the well of the
rear plug, said front plug providing a closure in
communication between the channel in the bot
the casing so that no fluid pressure can be com
tom of the rear plug and said pressure carrying
municated from the front chamber to the middle
conduit, interconnecting conduit means provid
chamber, a dynamic pressure transmitting con
ing o, communication duct from the region in
duit passing through the bottom channel of the
front of the front plug through the longitudinal
front plug and extending into the forward end of
conduit of the front plug and the channel of the
the bottom well of the rear plug, said conduit
second plug to the dynamic pressure carrying
having an upwardly curved forward part in th'e
conduit, said rear plug having additional chan
front chamber so that its end terminates inside
nels extending entirely therethrough longitudi
nally to provide a free communication between. 40 near the top of the casing, said dynamic pressure
transmitting conduit fitting snugly into said plugs
the region to the front of the rear plug and the
ward end for receiving air under dynamic pres
rear of the rear plug, a static pressure conduit
so that there be no communication between the
communicating with' a region to the rear of the
rear plug for connection to an indicating instru
first and second chambers and the second cham
ber and the bottom well of the rear plug, a verti
cal channel at the rear end of the rear plug pro
viding a communication between the bottom well
of the rear plug and the top portion of the rear
end of the rear plug, a seco-nd dynamic pressure
ment.
Ll. A Pitot-static tube comprising, in combina
tion. an elongated casing pointed at the front end
having an opening at the front for receiving the
dynamic pressure of the fluid flowing with refer
ence to the Pitot-statíc tube, a front plug and
transmitting conduit extending through the top
a rear plug within the casing and a rear closure
portion of the rear plug into the vertical channel
for transmitting to an indicating instrument the
for the casing, said plugs and closure dividing the
dynamic pressure of the fluid ñowing past the
casing.
‘
casing into a front chamber, a middle chamber
6. A Pitot-static tube comprising, in combina
and a rear chamber, said front plug being pro
vided with a longitudinal channel at the top and 55 tion, an elongated casing pointed at the front end
having an opening at the front for receiving the
a second longitudinal channel at the bottom, said
dynamic pressure of the fluid flowing with refer
rear plug being provided with a longitudinally
ence to the Pitot-statio tube, a front plug and a
disposed well at the top of a given depth, and
rear` plug within the casing and a rear Closure for
being provided with a second longitudinally dis
posed well at the bottom of the plug, a single GO the casing, said plugs and closure dividing the
casing into a front chamber, a middle chamber
elongated electrical heating unit in the upper
and a rear chamber, said front plug being pro
channel of the front plug and the upper well of
vided with a longitudinal channel at the top and
the rear plug, said single elongated electrical
a Second longitudinal channel at the bottom, said
heating unit having more heating sections in the
channel of the front plug than in the well of the (35 rear plug being provided with a longitudinally dis
posed well at the top of a given depth, and be
rear plug, said front plug providing a Closure for
ing provided with a second longitudinally dis
the casing so that no fluid pressure can be com
posed well at the bottom of the plug, a single
municated from the front chamber to the middle
elongated electrical heating unit in the upper
chamber, a dynamic pressure transmitting con
channel of the front plug and the upper well of
duit passing through the bottom channel of the
front plug and extending into the forward end
of the bottom well of the rear plug, said dynamic
pressure transmitting conduit fitting snugly into
said plugs so that there be no communication
between the first and second chambers and the
the rear plug, said single elongated electrical
heating unit having more heating sections in the
channel of the front plug than in the well of the
rear plug, said front plug providing a closure in
the casing so that no fluid pressure can be com
2,404,978
9 »,
municated from the front chamber to the middle
chamber, a dynamic pressure transmitting con
duit passing through the bottom channel of the
front plug and extending into the forward end of
the bottom well of the rear plug, said conduit
being curved upwardly in the front chamber and
the extreme upper end of the curved part being
closed but provided with side openings near the
closed end, said dynamic pressure transmitting
conduit fitting snugly into said plugs so that
10
ence to the Pitot-static tube, a front plug and a
rear plug within the casing and a rear closure for
the casing, said plugs and closure dividing the
casing into a front chamber, a middle chamber
and a rear chamber, said front plug being pro
vided with a longitudinal channel at the top and
a second longitudinal channel at the bottom, said
rear plug being provided with a longitudinallydisposed well at the top of a given depth, and
being provided with a second longitudinally dis
there be no communication between the first and
posed well at the bottom of the plug, a single
second chambers and the second chamber and
elongated electrical heating unit in the upper
the bottom well of the rear plug, a vertical chan
channel of the front plug and the upper well of
nel at the rear end of the rear plug providing a
communication between the bottom well of the 15 the rear plug, said single elongated electrical
heating unit having more heating sections in the
rear plug and the top portion of the rear end of
channel of the front plug than in the well of the
the rear plug, a second dynamic pressure tra-ns
rear plug, said front plug providing a closure in
mitting conduit extending through the top por
the casing so that no fluid pressure can be com
tion of the rear plug into the vertical channel for
transmitting to an indicating instrument the dy 20 municated from the front chamber to the middle
chamber, a dynamic pressure transmitting con
namic pressure of the fluid flowing past the cas
duit passing through the bottom channel of the
ing.
.
front plug and extending into the forward end
7. A Pitot-static tube comprising, in combina
of the bottom well of the rear plug, said conduit
tion, an elongated casing pointed at the front end
having an upwardly curved forward part in the
having an opening at the front for receiving the
ñrst chamber so that its end terminates inside
dynamic pressure of the fluid flowing with refer
near the top of the casing, said dynamic pressure
ence to the Pitot-static tube, a front plug and a
rear plug within the casing and a rear closure for
transmitting conduit ñtting snugly into said plugs
the casing, said plugs and closure dividing the
so that there be no communication between the
first and second chambers and the second cham
ber and the bottom well of the rear plug, a verti
cal channel at the rear end of the rear plug pro
viding a communication between the bottom well
of the rear plug and the top portion of the rear
end of the rear plug, a second dynamic pressure
casing into a front chamber, a middle chamber
and a rear chamber, said front plug being pro
vided with a longitudinal channel at the top and
a second longitudinal channel at the bottom, said
rear plug being provided with a longitudinally dis
posed well at the top of a given depth, and being "
provided with a second longitudinally disposed
well at the bottom of the plug, a single elongated
electrical heating unit in the upper channel of
the front plug and the upper well of the rear plug,
said single elongated electrical heating unit hav
ing more heating sections in the channel of the
front plug than in the well of the rear plug, said
front plug providing a closure in the casing so
that no fluid pressure can be communicated from
the front chamber to the middle chamber, a
dynamic pressure transmitting conduit passing
through the bottom channel of the front plug and
extending into the forward end of the bottom well
of the rear plug, said dynamic pressure transmit
ting conduit fitting snugly into said plugs so that
there be no communication between the first and
second chambers and the second chamber and
the bottom well of the rear plug, a vertical chan
nel at the rear end of the rear plug providing a
communication between the bottom well of the
rear plug and the top portion of the rear end of
the rear plug, a second dynamic pressure trans
transmitting conduit extending through the top
portion of the rear plug into the vertical channel
for transmitting to an indicating instrument the
dynamic pressure of the fluid flowing past the
casing, a baille at the lower forward end of the
second dynamic pressure transmitting conduit,
said casing being provided with moisture drain
means at the bottom of the casing substantially
directly in front of the front plug, and said cas
ing and rear plug being provided with moisture
drain means at the bottom and at the region of
the vertical channel so that a communication is
established between the vertical channel and the
outside.
9. A Pitot-static tube comprising, in combina
tion, an elongated casing pointed at the front end
having an opening at the front for receiving the
dynamic pressure of the fluid flowing with refer
ence to the Pitot-static tube, a front plug and
a rear plug within the casing and a rear closure
for the casing, said plugs and closure dividing
the casing into a front chamber, a middle cham
ber and a rear chamber, said front plug being
provided with a longitudinal channel at the top
tion of the rear plug into the vertical channel
for transmitting to an indicating instrument the 60 and a second longitudinal channel at the bottom,
said rear plug being provided with a longitudi
dynamic pressure of the fluid flowing past the
nally disposed well at the top of a given depth,
casing, a baille at the lower forward end of the
and being provided with a second longitudinally
second dynamic pressure transmitting conduit,
disposed well at the bottom of the plug, a single
said casing being provided with moisture drain
mitting conduit extending through the top por
means at the bottom of the casing substantially 65 elongated electrical heating unit in the upper
channel of the front plug and the upper well 0f
directly in front of the front plug, and said cas
the rear plug, said single elongated electrical
ing and rear plug being provided with moisture
heating unit having more heating sections in the
drain means at the bottom and at the region of
the vertical channel so that a communication is
channel of the front plug than in the well of the
rear plug, said front plug providing a closure in
established between the vertical channel and the 70
the casing so that no fluid pressure can be com
municated from the front chamber to the middle
8. A Pitot-static tube comprising, in combina
chamber, a dynamic pressure transmitting con
tion, an elongated casing pointed at the front end
duit passing through the bottom channel of the
having an opening at the front for receiving the
outside. '
dynamic pressure of the fluid flowing with refer
front plug and extending into the forward end
of the bottom well of the rear plug, said dynamic
2,404,978
pressure transmitting conduit ñtting snugly into
said plugs so that therebe no communication
between the first and second chambers and the
second chamber and the bottom well of the rear
plug, a vertical channel at the rear end of the
rear plug providing a communication between
the bottom well of the rear plug and the top por
tion- of the rear end of the rear plug, a second
i2
a communication of the static pressure to an
indicating instrument.
1l. A Pitot-static tube comprising, in combina
tion, an elongated casing pointed at the front
dynamic pressure transmitting conduit extending
through the top portion of the rear plug into the
vertical channel for transmitting to an indicat
ing instrument the dynamic pressure of the ñuid
end having an opening at the front for receiving
the dynamic pressure of the fluid flowing with
reference to the Pitot-static tube, a front plug
and a rear plug within the casing and a rear
closure for the casing, said plugs and closure
dividing the casing into a front chamber, a mid
dle chamber and a rear chamber, said front plug
being provided with a longitudinal channel at
the top and a second longitudinal channel at the
bottom, said rear plug being provided with a
provided with means both at the bottom and the
longitudinally disposed well at the top of a given
top of the casing substantially directly in front
depth, and being provided with a second longi
of the rear plug to receive the static pressure of
tudinally disposed well at the bottom of the plug,
the fiuid outside of the casing, said rear plug
a single elongated electrical heating unit in the
having channels for providing a substantially free
upper channel of the front plug and the upper
communication between the middle chamber and
well of the rear plug, said single elongated elec
the rear chamber, and a static pressure trans 20 trical heating unit having more heating sections
mitting conduit extending through the rear
in the channel of the front plug than in the well
flowing past the casing, said casing also being
closure for providing a communication of the
of the rear plug, said iront plug providing a
static pressure to an indicating instrument.
closure in the casing so that no fluid pressure
l0. A Pitot-static tube comprising, in combina
can be communicated -from the front chamber
25
tion, an elongated casing pointed at the front
to the middle chamber, a dynamic pressure trans
»end having an opening at the front for receiving
mitting conduit passing through the bottom
the dynamic pressure of the fluid ñowing with
channel of the front plug and extending into
reference to the Pitot-static tube, a front plug
the forward end of the bottom well of the rear
and a rear plug within the casing and a rear
closure for the casing, said plugs and closure
dividing the casing into a front chamber, a mid
dle chamber and a rear chamber, said ~front plug
being provided with a longitudinal channel at
the top and a second longitudinal channel at the
bottom, said rear plug being provided with a ‘
longitudinally disposed well at the top of a given
depth, and b-eing provided with a second longi
tudinally disposed well at the bottom of the plug,
a single elongated electrical heating unit in the
upper channel of the front plug and the upper 40
well of the rear plug, said single elongated elec
trical heating unit having more heating sections
in the channel of the front plug than in the well
of the rear plug, said front plug providing a
closure in the casing so that no fluid pressure
can be communicated from the front chamber
to the middle chamber, a dynamic pressure
transmitting conduit passing through the bottom
channel of the front plug and extending into the
plug, said dynamic pressure transmitting conduit
fitting snugly into said plugs so that there be
no communication between the ñrst and second
chambers and the second chamber and the bot
tom well of the rear plug, a vertical channel at
the rear end oi the rear plug providing a com
munication between the bottom well of the rear
plug and the top portion of the rear end of the
rear plug, a second dynamic pressure transmit
ting conduit extending through the top portion
or" the rear plug into the vertical channel
transmitting to an indicating instrument
dynamic pressure of the fluid flowing past
casing, a baiiie at the lower forward end of
for
the
the
the
second dynamic pressure transmitting conduit,
said casing being provided with moisture drain
means at the bottom of the casing substantially
directly in front of the front plug, and said cas
ing and rear plug being provided with moisture
drain means at the bottom and at the region of
the vertical channel so that a communication
forward end of the bottom well of the rear plug, 50
said conduit having an upwardly curved forward
part in the iirst chamber so that its end termi
nates inside near the top of the casing, said
dynamic pressure transmitting conduit fitting
snugly into said plugs so that there be no com
is established between the vertical channel and
the outside, said casing also being provided with
means both at the bottom and the top of the
casing substantially directly in front of the rear
plug to receive the static pressure of the iluid
outside of the casing, said rear plug having chan
nels for providing a substantially free communi
cation between the middle chamber and the rear
munication between the first and second cham
bers and the second chamber and the bottom
well ci the rear plug, a vertical channel at the
chamber, and a static pressure transmitting con
rear end of the rear plug providing a communi
duit extending through the rear closure for proE
cation between the bottom well of the rear plug 60 viding a communication of the static pressure to
and the top portion of the rear end of the rear
an indicating instrument.
plug, a second dynamic pressure transmitting
12. A Pitot-static tube comprising, in combi
conduit extending through the top portion of
nation, an elongated casing pointed at the front
the rear plug into the vertical channel for trans
end having an opening at the fro-nt for receiving
mitting to an indicating instrument the dynamic
the dynamic pressure of the fluid flowing with
pressure of the fluid ñowing past the casing, said
reference to the Pitot-static tube, a front plug
casing also being provided with means both at
and a rear plug within the casing and a rear
the bottom and the top of the casing substan
closure for the casing, said plugs and closure di
tially directly in front of the rear plug to receive
viding the casing into a front chamber, a middle
the static pressure of the ñuid outside of the
chamber and a rear chamber, said front plug
casing, said rear plug having channels for pro
being proidded with a longitudinal channel at the
viding a substantially free communication be
top and a second longitudinal channel at the
tween the middle chamber and the rear chamber,
bottom, said rear plug being provided with a lon
and a static pressure transmitting conduit eX
tending through the rear closure for providing 75 gitudinally disposed well at the top of a given
13
2,404,978
depth, and being provided with a second longi
tudinally disposed well at the bottom of the plug,
a single elongated electrical heating unit in the
upper channel of the front plug and the upper
well of the rear plug, said single elongated elec
trical heating unit having more heating sections
in the channel of the front plug than in the well
of the rear plug, said front plug providing a
closure in the casing so that no fluid pressure
can be communicated from the front chamber
to the middle chamber, a dynamic pressure trans
mitting conduit passing through the bottom chan
nel of the front plug and extending into the
forward end of the bottom well of the rear plug,
said conduit having an upwardly curved forward
14
dividing the casing into a front chamber, a mid
dle chamber and a rear chamber, said front plug
being provided with a longitudinal channel at
the top and a second longitudinal channel at the
bottom, said rear plug being provided with a lon
gitudinally disposed well at the top of a given
depth, and being provided with a second longi
tudinally disposed well at the bottom of the plug,
a single elongated electrical heating unit in the
upper channel of the front plug and the upper
well of the rear plug, said single elongated elec
trical heating unit having more heating sections
in the channel of the front plug than in the well
of the rear plug, said front plug providing a clo
sure in the casing so that no iluid pressure can
be communicated from the front chamber to the
middle chamber, a dynamic pressure transmitting
part in the first chamber so that its end termi
nates inside near the top of the casing, said dy
namic pressure transmitting conduit fitting snug
conduit passing through the bottom channel of
ly into said plugs so that there be no communi
the front plug and carried upwardly in the front
cation between the first and second chambers 20 chamber and extending into the forward end of
and the second chamber and the bottom well of
the bottom well of the rear plug, the extreme
the rear plug, a vertical channel at the rear end
upper end of the curved part extending into the
of the rear plug providing a communication be
front chamber being closed but provided with
tween the bottom well of the rear plug and the
side openings near the closed end, said dynamic
top portion of the rear end of the rear plug, a
pressure transmitting conduit fitting snugly into
second dynamic pressure transmitting conduit
said plugs so that there be no communication be
extending through the top portion of the rear
tween the first and second chambers and the
plug into the vertical channel for transmitting
second chamber and the bottom well of the rear
to an indicating instrument the dynamic pressure
plug, a vertical channel at the rear end of the
of the ñuid flowing past the casing, a baille at « rear plug providing a communication between
the lower forward end of the second dynamic
the bottom Well of the rear plug and the top por
pressure transmitting conduit, said casing being
tion of the rear end of the rear plug, a second
provided with moisture drain means at the bot
tom of the casing substantially directly in front
of the front plug, and said casing and rear plug -
being provided with moisture drain means at the
bottom and at the region of the vertical channel
so that a communication is established between
the vertical channel and the outside, said casing
also being provided with means both at the bot
tom and at the top of the casing substantially
directly in front of the rear plug to receive the
static pressure of the fluid outside of the casing,
said rear plug having channels for providing a
substantially free communication between the
middle chamber and the rear chamber, and a
static pressure transmitting conduit extending
through the rear closure for providing a com
munication of the static pressure to an indicating
dynamic pressure transmitting conduit extending
through the top portion of the rear plug into the
vertical channel for transmitting to an indicat
ing instrument the dynamic pressure of the fluid
flowing past the casing, a baflle at the lower for
ward end of the second dynamic pressure trans
mitting conduit, said casing being provided with
moisture drain means at the bottom of the casing
substantially directly in front of the front plug,
and said casing and rear plug being provided with
moisture drain means at the bottom and at the
region of the vertical channel so that a com
munication is established between the vertical
channel and the outside, said casing also being
provided with means both at the bottom and the
top of the casing substantially directly in front
of the rear plug to receive the static pressure of
instrument.
13. A Pitot-static tube comprising, in combi
nation, an elongated casing pointed at the front
50 the fluid outside of the casing, said rear plug
end having an opening at the front for receiving
the dynamic pressure of the fluid flowing with
reference to the Pitot-static tube, a front plug
ting conduit extending through the rear closure
having channels for providing a substantially free
communication between the middle chamber and
the rear chamber, and a static pressure transmit
for providing a communication of the static pres
and a rear plug within the casing and a rear 55 sure to an indicating instrument.
closure for the casing, said plugs and closure
ELDRED O. MORTON.
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