US2636121A

US2636121A - Automatically operated signaling apparatus

Info

Publication number: US2636121A
Application number: US76342A
Authority: US
Inventors: Raymond L Freas
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-02-14
Filing date: 1949-02-14
Publication date: 1953-04-21
Anticipated expiration: 1970-04-21

Description

April 21, 1953 R. FREAS AUTOMATICALLY OPERTED SIGNA-LING APPARATUS Filed Feb. 14, 194s R. m u of a me' A H @T17 w. L. M m m w .Illlll .I

.v oillllllli." lill Patented Apr. 21, 1953 UNITED STAT-fes oFF-ice UTOMATICALLY. OPERATEDJ1 TSIGNALING ABPARATU Raymond .L`Freas, Consholibcken, Pa; Application'Fbruaryff141949;SerialrNorsiz 2- ".Cl`ai`ms. (Cl. 2505331',

` Tl'iisinvention` pertains to the art of fsignall-ing,A andi-it `comprises apparatus" 'operablef-automat@ icallyto sendoutsignalsi Morerparticularly, theA deviceA of Nthe invention is adaptedrtobe thrown e to` tlfie'fea-rtlfi `from amoving vehicle: WhenmitL4 reaches' the 'earth the device" conditions itself'au--- tomatically for 'transmitting `signals, and vtl'ere'm afterthel` device "operatesautomatically*to trans provements over tliefstructure .of myLprior appli-` n'ow ,abandonedf for AaA 'Radio Float, the subject matteriof-whiclr' isznowpending inthecontinuing* applicationseriaiiNo."sansa-med -June 1831948;

titled fAutomatically Operated Signalling Appaf The present invention 'embodies a novel exe-- anlimprovement, overtlre` antenna` disclosed inf-the hereinbefore referred itGappIications; SerialfNoz i 634313411'of"'Decemb'er i" 10,3 1945', andMSerial' No;- 331835'-oi`A Ji1ne18;"1948. The improved' antenna7 ten'sible". antenna construction,` Which-constitutes construction forms the-'subject matterl of my prior" copendingapplication; Seriali N o: 63 15,459,

iilieid November 28'; 1945,"nowabandoned; foran Automatically Erected. Antenna, of which-f the present 'applicationis a continuation.

Thepresent-.invention also embodiesnovelrop-f erating apparatus for erectingthe antennay'which* isan improvement` over-the antennaerectingap'-y v paratus of the hereinb'efore-referredato"applications, S'erial* No.' 634,134 offDecember-10,*1945;i

'3 proved antenna .erecting japparatusof"A the prese 5 ent" application ,forms subject `mattei' of my lcop'endingapplication; Serial-No; 645,424, filed Feb#- ruary'j4,"1946; now` abandoned', entitled fAiPressurized Floating Signalling Apparatus, of which"- and Serial N01 33,835 0f June-18,1948? The-imi the presentapplication isa continuation;

The novel' characteristicsl Aand various vadvan- -i tagesiotliel device'l ofA the present `iinvention@will. be understood ifrom the Yacc'ompany-ing tdrawingi:

In" the drawings Fig. 1 isa crossesecti'onal'elevation'through-the lngitudinal center plane' of the i apparatus of the invention,- certain parts 'appearing -in elevation', and with parts broken forclearnesszofi -illusf' Fig;n '2 is a fragmentary cross'sectional'elevaw -1 tion", showing ,a detail of the: buoyancychamber li'gt.V 3 is" Va Yfragmentary cross-sectional 'elevaf' tion,.illustrating 4the .antenna .in K erectedicond# tion;

2 Fier' 4 Lis* cross*section-taken 'onrline 4i-4 "of Fig'.f3-;'-"-

Fig. 5 is a perspective in crossfsection.- ill'iiis tratingone form of',- pressure-sealing piston emi bodied the'antenna, and

y Fgreisra similar perspective in" `cross-sectionW illustrating another "v form ofw pressure-'sealing pistonembodied in theantenna':

The device of the presentinventionembodiesa signalhtransmittingpradib When-the device :'is" thrownJ vfrom al movingvvehiclejxfrom' anfairpla'ne z in flight', forexamp'le, it*`op'era'tes automatically to condition itself Ato set' the radio in operation;Y and 1 thereafter the' radio operates automatically to send Lout v=`signals: The' inventionris'M particularly? useful duringgallight `overa ,large-'body of Water when-thepilot desires to check direction to' deter= Irl-ine'theA amount' of"`drift;"" the disclosed embodi' ment; therefore, being" particularlxconstructed to A operate'automaticallyv` when it" is" throwrrwintow portion oiitslengtlr extending away from the end` l i byotl'fermeans 'to' :Lbe describedzliereinafter:

At" itisendA remote from `the' 'bracket Y I 8;* the tube II'i' isattached to .the lbuoyancy chamber 25' by" means of thewsleeved 6'. The buoyancy chamber isMa an elongated-scan 2 I ihaving ,fa ^lid"2 8 of the chamber opposite the lid 28, i. e., the bottom of the can 2l', is provided with a tting 29 for attachment of the buoyancy chamber to the sleeve 26. The buoyancy chamber 25 is thus fastened to the tube II positioned around it, and it extends from the end attachment of fitting 29 and sleeve 25 lengthwise of the tube towards the bracket I8.

The source of electricity for the radio signalling apparatus is the battery which is the type that is inert but becomes activated by contact with water. When it is desired to put the apparatus in operation to send out signals while the launching craft is flying over a body of water, the battery 30 becomes energized by the apparatus being thrown into the water. This eliminates the need of electrical switches. Upon the battery becoming energized, it iirst suppliesl energy to the apparatus which operates to erect the antenna in a manner to be described more fully hereinafter. The battery thereafter continues as an electrical supply for the radio transmitter for sending out signals.

p The battery is constructed with the central aperture or hole 3| through which the tube I extends from the buoyancy chamber 25 to the end attachment thereof with bracket I8, the battery being thus positioned between the buoyancy chamber and the power pack I5. The battery 35 is attached to the bracket I8 and constitutes part of the ballast mass provided by the power pack I5. The hole 3| fits loosely around the tube II as shown, and has sufficient clearance for certain lines to extend through it that will be described more fully hereinafter. Posts 32 and 53 are attached to the end of battery 30, and serve to secure the battery to the bracket I8 by means of the respective bolts 24 and screw 34. Steadying bracket 35 is secured to the end of battery 39 and fits snugly around the exterior surface of reinforcing sleeve I9 thereby to make the attachment of battery 30 to the tube I| more rigid.

In accordance with the described construction, the buoyancy chamber 25 and the battery 39 constitute an elongated structure of generally cylindrical contour, with the power pack I5 attached to one end thereof, and the tube II provides a concentrically located central frame that supports the various components of the apparatus.

,. For attaching the buoyancy chamber 25 to one ,s

end of tube II, the sleeve 26 is screw-threaded to the end of the tube I I remote from the bracket I8 and is extended through the tting 29 of the buoyancy chamber 25. The inside nut is screw-threaded onto the sleeve 2B and is brought into engagement with the fitting 29 on the inside of the can 21. The outside nut 'II is also threaded onto sleeve 26, and is tightened into the tting 29 opposed to the inside nut 4I), suitable gaskets 42 being provided to make the attachment watertight. The water seal or packing nut 45, including suitable gaskets 45, are provided to make the attachment watertight along the screw threads between the sleeve 26 and the nuts 40 and 4|.

By means of the described construction, the end The antenna I 2 in collapsed condition is housed in the tube I I and is adapted to be erected by being extended out of the outboard end of the tube II that embodies the sleeve 26. In its collapsed condition, the antenna is enclosed in the tube I I by 4means of the disc 50 of blotting paper or the like material that disintegrates and loses its strength when it is placed in contact with water. The disc 50 is held clamped against the end surface of the sleeve 2S by means of the end collar 5I, and is reinforced by the disc 52 of metal or the like material to which it is attached by means of the central rivet 53. The metal disc 52 fits loosely in the bore of the collar 5| and is positioned therein until the antenna I2 is erected. The metal disc 52 has a larger diameter than the bore of the sleeve 25 and thus prevents collapse of the blotter disc 50 in the event it is hit during normal handling of the device of the invention.

The lighter-weight components of the signalling apparatus are preferably housed in the buoyancy chamber 25, and these in general constitute the transmitting components of the radio. The transmitting components are generally larger than components of the power pack and are less rugged, and they are protected against injury by being housed in the buoyancy chamber. The cable 55 connects the components that are housed in the buoyancy chamber 25 with the power pack I5, and extends from the power pack through the hole 3| of battery 30 to the lid 28 oi the buoyancy chamber. The cable 55 enters the buoyancy chamber 25 through the watertight grommet 55 of rubber or the like suitable material, which is attached to the lid 28 in any suitable manner as shown.

The structure described so far is similar to the disclosure of the copending application, Serial No. 33,835, and is adapted to be operated in the same manner. Accordingly, the complete device includes a parachute, which is constructed and attached to the ballast mass I5 in the same manner as in the copending application, and requires no further description herein.

Any suitable radio transmitter can be employed having any suitable circuit. For example, the circuit can be the same as is disclosed in the copending application. In the embodiment of the present application, capacity tuning is disclosed. and is available alternatively with the inductance tuning of the copending disclosure.

.The fixed plate 5l' is clamped to the sleeve 26 by means of nut 53, and is electrically connected to the transmitting component housed in the chamber 25 by means of lead 59. The movable plate 50 is threaded into the iitting 6I, which extends through the wall of the chamber 25 and is suitably located to enable the plate 69 to be adjustably positioned towards or away from the xed plate 5l for tuning, the adjustment being made from the exterior of the chamber 25. The fitting 6I is attached to the can 2l in a fluidtight manner` by brazing, soldering or the like, and the cap 52 is provided to close the tting and render it completely watertight and airtight in use.

The buoyancy chamber 25 of the present application diifers from the buoyancy chamber in the copending application, Serial No. 33,835, in that chamber 25 is pressure tight. In the earlier construction of the copending application, the buoyancy chamber is under atmospheric pressure, and air passages are provided that permit air to pass out of and into the chamber to and from the exterior atmosphere. The lid 28 of chamber 25 is sealed tothe can 21 at 63, by soldering, brazing or the like, and provision is made to place the chamber 25 under fluid pressure.

The valve '65, Fig. .2, is provided, to enable air or other suitable fluid under pressure to be fed into the 4buoyancy chamber 25. The operating mechanism of the valve 65 of the disclosed embodiment is the `same in all particulars as the type `of air valve that is conventional and wellknown in automotive tires. It is therefore not deemed necessary herein to describe the structure of valve 65 in detail. In actual reduction of the invention to practice, applicant provided the tting 66 `in the `bottom end of can 21, the fitting 66 being adapted to accommodate a conventional .automotive tire valve, and this construction has proven entirely satisfactory. In practice, the buoyancy chamber 25 :is preferably placed under pressure of about one atmosphere, but the pressure can -be varied within'wide limits to suit particular needs.

The chamber 25 may be provided with other fittings, such as the fitting 61, for example, which permits access to the interior of the chamber for particular purposes that are unimportant for understanding the present invention.

Bracket I8 includes the enclosure of cavity 10, to which the buoyancy chamber 25 is connected by means of the tubing or duct 1I. The lid 28 is provided with the tting 12 to which one end of the duct 1I is attached by soldering or the like. The other end of duct 1I is similarly attached to fitting 13 of the bracket IB and thereby communicates with the cavity 18. The duct 1I preferably passes from the buoyancy chamber 25 to the fitting 13 through the hole 3l in battery 38.

The cavity 10 is closed at its end remote from the tting 13 by the diaphragm 15 of sectile material which, in the disclosed embodiment, comprises a disc of thin sheet metal. The diaphragm 15 is held in place by means of the fitting 16, suitable gaskets being provided to seal the cavity 18 fluidtight.

rllhe bracket I8 embodies the nipple 11, which is threaded exteriorly to receive the nut 18. This serves as an attachment of the plate 23 to the bracket I8 in addition to the bolt 24 previously described.

The nipple 11 provides an enclosure or cavity 19, which' is connected with the cavity 10 through the bore or duct 88 of the fitting 16. The diaphragm I constitutes a wall or partition that prevents communication between the cavities and 19.

The cavity I4 of nipple I1 communicates with the interior of tube Il through the tubing 8| that is fastened in the bore of, and forms a lining for, the end sleeve I6 of the tube I I. The cavity I4 of nipple I1 communicates with the cavity 19 of nipple 11 through the duct 82, whereby the cavity 19 is in constant communication with the tube I I.

Mechanism, generally designated 85, is operable to pierce the diaphragm and open a passage through it, thereby operating to` connect the cavities 10 and 19 and connect the buoyancy chamber 25 with the antenna housing tube I I for fluid flow thereto. The cap 86 is threaded exteriorly of nipple 11, and comprises the axial bore 81 that embodies a combustion chamber. A suitable explosive 88 is conned in a predetermined space Within the chamber 81 by one or more partitions 89 of celluloid or the like combustible material. The ring device 98 is threaded into the bore of cavity 81, and conines the combustion chamber. The Jring device is an electrical heating unit, and comprises the resistance .coil 9I, which is fed through the lead 92 from battery 30 as a sourceof electricity. The heating unit is provided by .reconstructing an automotive spark plug, this being done by connecting the resistance wire9I across` the spark gap. The cap 93 houses the firing device 9|) asshown, and includes the eye `94, to which a parachute is attached in the manner disclosed incopendinglapplication Serial No. 33,835.

The `bore of cavity 19 serves the purpose of a cylinder in which the plunger or piston operates. The pin 96 is attached to the plunger 95, and extends into the bore 80 of the fitting 16 in which pin 96 is guided during travel of the plunger 95. The compression spring 91 acts againstthe plunger 95 -and urges it into abutment with the cap 86. The pin '96 is pointed at its end 98 for piercing the diaphragm 15, and ducts 99 extend through the pin 96 from its end 98 embodying the point to the cavity 19. Thus, iluid under pressure is enabled to iicw from cavity 10 into cavity 19 when the diaphragm 15 is pierced by the point 98 of pin 96.

Operation of the device will now be described with reference to the disclosed embodiment, which is particularly adapted to be thrown to the earth from an aircraft in iiight over a body of Water. When the apparatus is launched, it descends to the earth hanging from a parachute in the manner described fully in the copending application Serial No. 33,835. The sleeve 26 at the outboard end of the tube I I is directed down- Wardly during the descent, and therefore the disc 58 of blotting paper is first submerged in the water and begins -to disintegrate and lose its strength.

When the device becomes deposited on the body of water, the ballast mass I 5, including battery 39, sinks and the buoyancy chamber 25 floats on the surface. The sleeve 26 thereby comes to the top, and the bottom of can 21 with the end collar 5I of sleeve 26 projects above the surface of water. The battery 38 being under Water, it thereby becomes energized. Electricity is supplied to the ring device 96 from the battery 30, causing the heating coil 9I to become heated. When the temperature of coil 9| becomes high enough to detonate the explosive 88, combustion takes place in the chamber 81, and pressure of gas expansion is generated that actuates the plunger 95 in opposition to the spring 91. The point 98 of the pin 96 is thereby driven through the diaphragm 15. 1

This releases the iiuid under pressure contained within the buoyancy chamber 25, and permits it to flow into tube II, passing through the ducts 99 of pin 96 into cavity 19, and to the interior of the tube II through duct 82, the cavity I4 of nipple l1, and the lining tubing 8| of the end sleeve I6 of tube I I.

The pressure fluid supplied to the tube I I by the buoyancy chamber 25 is not excessively violent. Combustion of the explosive 88 operates under much greater pressure, but the operating pressure of the explosive continues for a much shorter length of time. The operating characteristics of an explosive may vary and are not predictable precisely. With the device of the present invention, operation of the explosion is quick, .and invariably sufficiently forceful to drive the pointed end 98 of pin 96 through diaphragm 15. The pressure fluid from thebuoyancy chamber 25-operateswith'a steady andpersstent'foc.

The Volume of the buoyancy chamber is great enough to prevent appreciable pressure loss due to volumetric displacement of the antenna.

The disc 50 of blotting paper having lost its strength by having been submerged, the release of the pressure fluid from buoyancy chamber 25 into the tube |I operates to push the antenna I2 out of the end of sleeve 20, and it shears the disc 50 Without encountering appreciable resistance. The pressure iluid exerts a steady force with continuing uniform magnitude, which operates to erect antenna I2, and as the apparatus rolls and bobs on the surface of the water this operates to agitate the antenna I2 within the tube I I to thereby assist in the operation of erecting the antenna.

The antenna comprises the outer tube that ts loosely inside the housing tube |I, and the successively smaller tubes |02, |03 and |04 that t loosely, one inside the other. The tubes |0|, |02, |03 and |00 are approximately of equal length, and are nested each inside the next larger tube in the manner illustrated in Fig. 1. Between the smallest and largest tubes, |00 and |0| respectively, there are as many intermediatesized tubes as are required to provide the required total length of antenna |2. The tubes of antenna i2 are constructed of any suitable metal, aluminum tubing having been employed in the disclosed embodiment with results that are entirely satisfactory.

The rims of opposite ends of each of the antenna tubes |0I, |02, |03 and |04 are rolled, the inboard end of each tube being spun outwardly to embody the outwardly directed bead |00 and the outboard end or each tube being spun inwardly to embody the inwardly directed 'bead |06. Each smaller tube |00, |03 and |02 is thereby adapted to be inserted into the inboard end of its next larger tube |03, |02 and |05 respectively, and to be projected through its next larger tube until the trailing or inboard end of the smaller tube reaches the outboard end of its next larger tube. The respectively outwardly and inwardly directed beads |05 and |06 overhang each other, and are accordingly disposed in opposed relationship when the inboard end of each smaller tube approaches the outboard end of its next larger tube. This prevents any smaller tube from being projected through and out of its next larger tube, and operates to hold the several tubes attached to each other end to end when the antenna I2 is in erected condition.

As illustrated in Fig. 3, each of the smaller tubes |02, |03 and I is provided with a spring contact |01 of bronze or the like electrically conducting material. Each spring contact II is attached to its tube |02, |03 or |00 near the inboard end thereof, and extends along the tube into a position proximate to the outwardly directed bead |05. The spring contact |01 is attached to and held in electrical contacting engagement with the outside surface of its tube |04, |03 or |02 by means of a wrapping of adhesive tape |03 that overhangs the inwardly directed bead |06 of the next larger tube |03, |02 and |0| respectively. The spring |0'| presses resiliently against the inside surface of the next larger tube, thereby maintaining electrical contact between tubes throughout the distance of their relative movement. When the antenna is erected by the smaller tubes |04, |03 and |02 being actuated in an outboard direction through their respective next larger tubes |03, |02 and |0I, the Wrappings |08 are driven into engage- 8 ment with the beads |00, and being yielding they permit movement of the springs I0'I that causes them to jam between their outwardly turned beads |05 and the inside surface of the respective next larger tube |03, |02 or |0I.

Near its inboard end, each smaller tube |04, |03, |02 is provided with a radial enlargement |00 located at a distance from the end of the tube to position it just beyond the beaded end |00 of the next larger tube |03, |02, IOI respectively, when the antenna I2 is in fully erected condition. One or more properly circumferentially positioned pimples provide a satisfactory radial enlargement |09, and serve as an additional means to inhibit collapse of the antenna after it has been extended to its erected condition.

The largest tube |0| is provided with a resilient connector ||0 near its inboard end, which holds the antenna I2 mechanically in erected condition and also serves as an antenna coupling.

As seen in Fig. 3, the sleeve 26 has a main bore ||5 approximately the same size as the bore of the tube I On its end that is threaded to the tube sleeve 26 is provided with a counterbore IIS of somewhat larger diameter than the main bore H5, the counterbore ||6 forming an annular recess in association with the end of tube II. The resilient connector ||0 of the tube |0| engages the annular recess ||6 to hold the antenna I2 in erected position. Near its inboard end, the largest tube |0| of the antenna is provided with a diametrically disposed aperture in which the plungers IIS are guided for movement radially. Spring operates to press the plungers I I8 radially outwardly against the inside wall of the tube when the antenna is in collapsed condition of Fig. l, the antenna circuit being then open because of the dielectric properties of tube During movement of tube |0| out of the end of the tube II that includes the sleeve 26, when the plungers I|8 reach the end of the tube II they are actuated into the recess EIS by the spring II. The plungers IIS constitute latching means that holds the antenna mechanically in erected position. Plungers HS also make electrical contact between the tube |D| and sleeve 26, thereby coupling the antenna |2 electrically with the fixed plate 5l of the radio transmitter.

A metal bushing IIQ, Figs. 3 and 4, of bronze or the like friction resisting material, provides a bearing guideway for the plungers I I8. The rubber mount |20 contains the bushing ||9, and is pressed inside the tube in position to locate and hold the latch ||8 of the holding device ||0 in position. The rubber mount |20 is provided with ports I2|, the function of which will be made clear hereinafter.

At its inboard end, each tube |02, |03, |02 and |0I is provided with yielding piston |25, |26, |21, |28, respectively, of rubber or the like resilient material.

By means of this construction, the pressure iluid from the buoyancy chamber 25 that enters tube passes through the axial aperture |38, Fig. 3, of piston |28, which communicates through the ports |2| of the rubber mount |20 to permit pressure fluid to enter tube The pressure fluid enters tube |02 through piston |21, and enters tube |03 through the aperture |33 of piston |26. The pressure fluid acts against the closed plug |25 of tube |04 to project tube |04 lengthwise out of the outboard end |06 of tube |03. Tubes |03, |02 and |0| are pushed out of the Outboard ends of respective tubes |02, |0| and in a similar manner by operation of pressure fluid in tube |03 against the closed piston |25. This action continues until the several tubes |04, |03, |02 and |0| reach the limits of their movements in the outboard direction, when the respective outwardly and inwardly directed beads and |06 of next adjacent tubes oppose each other, in each instance with a spring |01 between them. When the latching plungers ||8 move into the annular recess I6 of sleeve 26, the antenna |2 is then in erected condition, and is coupled to the radio transmitter.

At its outboard end, the smallest tube |04 is provided with a button |22 of rubber or the like material, which serves as a buffer that operates against the blotter disc 50 to push the discs 50 and 52 out of the collar 5| and out of the way when the antenna l2 is erected. The button |22 overhangs the outside diameter of the smallest tube |04, and also overhangs the end of the next larger tube |03, to thereby hold the tube |04 located in the inboard direction within the tube |03 when the antenna is positioned in collapsed condition. This prevents the piston |25 from being held in crushed condition against the piston |26 of tube |03. `See Fig. 1.

The lining tubing 8| of the end sleeve I6 of tube abuts against the shoulder |39 of piston |28 interiorly of its apron and provides a stop that limits movement of the antenna I2 in the inboard direction of the tube and serves to locate the antenna in collapsed condition housed Within the tube The tubing 8| prevents the apron of piston |28 from being held in crushed condition when the antenna |2 is in collapsed condition. See Fig. 1.

The disclosed structure is one practical embodiment of the invention, and does not limit its scope, which is determined by the accompanying claims.

The invention described herein may be manufactured and used by'or for the Government oi.' the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. In signalling apparatus adapted to operate from the surface of a body of water, a buoyancy chamber containing fluid under pressure, an antenna extensible by the operation of iluid under pressure, a housing tube containing the antenna vin collapsed condition, a iiuid passage from the buoyancy chamber to the tube, the :fluid passage being normally in closed condition, and mechanism operable by the apparatus being deposited in water to open the iluid passage.

2. In signalling apparatus adapted to operate from the surface of a body of water, a buoyancy chamber containing fluid under pressure, an antenna extensible by the operation of iluid under pressure, a tube containing the antenna in collapsed condition, a fluid passage from the buoyancy -chamber to the tube, a diaphragm sealing the rluid passage, and mechanism operable by the apparatus being deposited in water to pierce the diaphragm for fluid now therethrough.

3. An extensible antenna comprising a plurality of metallic tubes containing one another telescopically, each tube compriisng an outwardly-turned bead integral with the tube at its one end, each larger tube comprising an inwardly-turned bead integral with the tube at its other end that overhangs the outwardly-turned bead of the next smaller tube, a housing tube of conductor material containing the antenna in co1- lapsed condition, a contact spring attached to each smaller tube near its end adjacent the outwardly-turned bead and bearing resiliently against the inside surface of the next larger tube in electrical contacting engagement therewith, an adhesive tape wrapped around each contact spring and its tube to attach the spring to the tube and hold it in electrical contacting engagement therewith, the adhesive tape wrapping extending away frcmthe surface of its tube far enough to overhang the inwardly-turned bead of the next larger tube.

4. An extensible antenna -comprising a plurality of metallic tubes containing one another telescopically, each tube comprising an outwardly-turned bead integral with the tube at its one end, each larger tube comprising an inwardly-turned bead integral with the tube at its other end that overhangs the outwardly-turned bead of the next smaller tube, a housing tube of conductor material containing the antenna in collapsed condition, a contact spring attached to each smaller tube near its end adjacent the outwardly-turned bead and bearing resiliently against the inside surface of the next larger tube in electrical contacting engagement therewith,

the housing tube being open at the end thereof remote from the pistons of the antenna tubes, an internal annular recess in the housing tube near the open end thereof, an electrical contact spring-pressed radially outwardly of the largest antenna tube into engagement with the inside surface of the housing tube, and positioned to lodge in the annular recess when the antenna is erected.

5. In signalling apparatus that is normally inoperative, a chamber containing uid under pressure, an antenna eXtensible by operation of fluid under pressure, an electrical signal sending instrument and an electrical power source therefore, and mechanism operable by the electrical power source when it energizes the signal sending instrument to connect the chamber with the antenna for uid ow thereto.

RAYMOND L. FREAS.

References Cited in the file of this patent UNITED STATES PATENTS Number