US 2398744 A
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D. c. JALBER-r 2,398,744
KITE BLLOON Apri; 16, 1946,
Filed Aug'. s1, 1945 3Sheets-Sheet 1 INVENTUR; DOMINA C. JALBERT D. c. JALBERT KITE BALLooN Filed Aug. 51, 1945 April 16, 1946.v
`3 Sheets-Sheet 2 mm E ma Q A m M O D D. c. JALBERT l 2,398,744
KITE BALLooN April 1.6, 1946.
Filed Aug..Y 51, 1945 3 Sheets-Sheet 3 DOMINA c. JALBERT l l v 81mm.
Patented Apr. 16, 1946 i KITE BALLooN Domina C.` ,Imbert-,Belmont Mass., assgnor *to` Dewey 'fand AlniyChemical Company, North Cambridge, setts..
`Masala corporation of Massachu- ApplicatimAgi'stsi, 1945, serial No. 613,886 A17 claims. .(01. 244-33) ,llhis invention relates tokite balloons., llAlthough, as will be apparent, the balloon may be adapted for manyjuses and may beproduced in numerous sizes, it Yis;paiticularly designed fr'sea rescue work.V The searescue model will be chosen j as the preferred example. ,i
. The limitations imposed by sea rescue mustbe borne in mind. Inthe rst place, the balloon must be light enough and small enough to be packedin an aviators ditching lrit. Its volume` cannot exceed the gas capacity of a sea gas genp erator. It must inflate f ully `at the very low pressures characteristic'of such a generator, In addition, the balloon must zbe simple, rugged and long lasting. lItumust,vcruithstand tropic sunshine and violentwinds. It must hold a radio lantenna and frequently other i notification devices aloft for an indefinite period,V and this must Abe accomplished with-26 ounces, of weight and `a spaceallotment of Ibut 125 cubic inches.' f f fi At present, aviators are `provided with sphericalfantenna balloon of about 30 cubic feet capacity and two collapsible boxlrites to launch when the wind forces the balloon down to thej sea. Admittedly, this is an unsatisfactory.` ex-` pedient, yet no kite balloon vention has been usable. The `most successful kite balloon, the common Ybarrage balloon, is too complicated in structure and design to .beprac ticablyfreduced to such proportions, andwhen reduced suffers from the characteristic of all kite balloons, which isthat the tension on `the flying cable 'rises steeply with.' increasing wind. In
small models, aerodynamic stability-i.` 'e., the 5;.,
ability of the balloon to y or be'towed without lunging or largest size of sea generator'will drogenwiuiift but 32 grams, the weight of the entireballoon and the flying cable orantenna amount of residual on free lift is necessary order to launch the balloon successfully.V It'fol@ lows that 1050 grams of material cannoti make a `strong enough structure toiwithstand the heavy wind Astrain thrown' on 4both the l antenna and the casing.
' It is arriongthe objectsI of this invention to' cable and casing,` Whichwill "maintain -it's aero-4` dynamic stability across a widera-nge of internal pressure. It is an additional object to produce until thisV present in`` yawing-all but vanishes. Since the produce but 401 cubic `feet or hydrogen and one cubic yfoot of hy'- together cannot eXcee'd105'0 grams; for a certain a small captiveballoon which maybe flown from sea level vto severalgtliousand feet without change or adjustmentL which isjself-adjusting to Vrapid changes in gasiyolume .such as are caused by tropic sunlight', and which `has long ying life. In additiom it isamongV the objects of this invention to produce ,a simple 4lfzitejballoon.which maybe packaged 'within the 'assigned size and weight limitations and ,may be completely inflated at very low pressures. I
`These and otherobjects will become apparent from the specification and from the drawings, in which: .Figure 1, shows a kite balloon embodying the present invention aloft and anchored to a life raft;A Q c.
` Figure 2, isa sidelview of the balloon withthe tailshown partlyfinsection;` I FigureB-is afragmentary perspective view of the' tail ofthe balloon; l; Figurel 4 iisrank explodedfview of that portion of the tail illustrated inllFigure 3; j
Figure 5 is an elevation partially in section of aportion of the tail strntv assembly;4
iuustrating the l I action of certain operating structures of the balloon; l' i Fig-ure Slis a cross-section through the balloon taken on the line 8-8 worliigure 1 when the balloon is modified to carry certain signalling equipment;A if .i .i i .i I. Figure- 9 isan enlarged fragmentary section taken on the line El.-9` of -Figure 8; i Figure 10is a fragmentary perspective view of the tail ofthe balloon,l incorporating a modified operating structure; j 4 l Figure 11 is a side elevation of a modified form ofthe balloonwhen fully inflated and in flight; Y
Figure 12 is the same Vview but illustrates the appearance of the balloon afterfsome gas has diffusedyand l Y Figures 13 and 14are transverse sections on a plane ofthe balloon located adjacent the tail. balloonwhen fully inflated; Figure lll-,shows the condition when diffusion has takenplace.` A
My kiteiballoon lacomprises a gas bladder I8,
within a fabriclcasing or envelope Ilcarrying 1 lifting fins and rudder fins I'l--I'L Preferably,
plastic fusion or cementing,
All parts are joined by'sewn :seamsr22 at their techniques; thermomaybe used. The distended by the gas bladder margins, but l.other seaming fabric casing I6 is I8, preferably a thin, gas-retentive membrane of polymerized chloro-butadiene 1,3. Other materials of a rubber-like nature are also useful, but have been found to be slightly more permeable to hydrogen. Because the steadiest flight characteristics are thereby secured, an ellipoidal shape is desirable yfor the nose and body portions of the casing I5. The tailfallsaway to aforeshortened mum casing diameter to the diameter at the tail, in the relation of small wholenumbers.V Ifjthe ratio is greater than this, the .tail will not inflate untiltoo high arpressurejisfreached.
The kite or lifting',` and the rudder orrstabilizing ns |1|1 are `approximately triangularvpieces of a strong fabric such as balloon cloth and are symmetrically .placed adjacent thertail Yin the vertical and horizontal axial planes of the bal' loon by sewing them to the casing along certain of the seams 22. The ns|1|1 are held distended by a strut assembly 25,`which will be described hereafter.
The elastic bladder I8 is of single piece con struction preferably formed to have relaxed dimensions approximately equal tothe dimensions of the casing or envelope vI6. Therefore, when fully inflated at sea level, the bladder isnot under material elastic stress. By avoiding elastic stress at sea level, theV balloon is 'given a"high"light ceiling, it has the ability to withstand substantial temperature changes; and V`full'inflation of the balloon at Very v'lowV initial pressures is possible. l f
The bladder I8 is 'placed inthe ycasing I6 through the hole '26, formed in the "tail patch 2|. The tail section'of the VbladderV terminates in the iniiation valve 21. As thisisthe standard rubber valve-nowI adoptedio'r sea rescue and meteorological balloons,A it vis not furthery described.
It should be noticed that the fins l1|1 Vdo not extend to the end ofthe tail, but that their tips are located several inches towards the nose of the balloon (see particularly Figure l1)1.- The tail Strut assembly 25 comprises a pressure plate 3B carrying radiating spring strut rods 3|-,fwhich are de'tachably held Vin `the Ysockets 35,' formed Iin the plate 30. To giveV collapsibility so vthat the struts may be folded into a parachute pack,v each rod consists of two telescopingmembers 33and 34 formed from a springy alloy of aluminum or imagnesium. When extendedjfthey are locked by. the spring-detent 36 'which isfcoiled around the member 33 'in 'such manner that it'stwo" ends131 extend through diainetrically opposite lholes 38 in the member 33. Thdete'ntslockby-drop-v ping -into a transverseholew AVinxthe member 34'. The free'endsjof'the struti rods V3 are fitted into fabric pockets 32 stitched to. the extreme tip of each n. The assembly is locatedby pass. ing the neckoffthe inflation'valve 21jthrougl1 a central aperture in the platel 3|L``V Since, when the balloon isz-inflated, theffln tipsdo'notflie inthe plane fof the pressure plate 30, but lie towards the nose, the strut rods 3| are substantially bowed and exert a strong back- Y Ward pull at the tip of each lin. This, in turn,
reacts through the pressure plate to urge the tail of the balloon inwards toward its nose. If collapsibility is unimportant, crossed wooden sticks or metal strut rods 3| lashed at their intersection 30- are equally `useful l(Figure 10).
The bridle or rigging 40 consists of two V- shaped loops 42 and 42', preferably parachute cords, made fast at each end to loop patches 43 sewn on the casing I6 and so located on the lune seams 22 that the forward pair and rear pair .of loop patches straddle the center of rotation of the balloon. The rear loop 42 of the bridle 4D terminates in an elastic link 45 which is preferably a strong rubber cord, but may be a metallic pull-spring. The outer end of the link X45 and the forward bridle 42 are made fast to the concentration ring 44 which may be equipped with a swivel 48, if desired. Themooringline 4| orA antenna is attached to the concentration ring assembly. y
The operation of the balloon is as follows. At the factory,' the pressure plate 30 is slid over the Valve stem 21 and xed in place. Then the tips of the strut rods 3| larey made fast in the fin pockets 32 so that there are no loose pieces of the assembly. The balloon is packed in a small, mill lboard box provided with aripping cord which should be tied to the raft before the user commences to iniiate'the balloon. A pull on the cord splits the box along its seams. inner end of the ripping cordis attached to a strong cord finger loop 46, which is made fast about the neck of the ination Valve -21. The nozzle ofthe sea generator isthen inserted in the Valve 21. Byslipping the loop 1G-'over the fingers and grasping the handle of the gas generator, the balloon inflates nose-up. Since the plate 30 is already in place, and the tips of the strut rods already made fast in the pockets 32, it is only necessary that, during inflation, the strut rods be extended and their' ends be slipped into lthe plate sockets' 35. The antenna snale 41 'is locked y'to bridle swivel 48.. When inflation is complete, the generatory nozzle is pulled out of the inflation valve, which automatically closes. Finally, the rip-cord mooring is ycast 01T and the balloon is away. Y
Conventional kite balloons increasetheir angle of 'attack as the wind velocity rises, and this characteristic has been amplified by designers since it steadies the balloon and reduces yaw. Quite` to. the contrary," my balloonr` presents its maximum Yangle of attack to the lightest wind and progressively decreases that angle vas the velocity rises. Yawing is overcome by making theY rudder surfaces atV leastA equal in area to the lifting planes. As the `wind increases,y link 45 stretches.` This pulls down the nose, elevates thev tail and reduces the lift to safe limits. Predetermined flight characteristics are given by choosingthe correct stress-strain characteristics ofthe link `45..
Assume a light Wind blowinginthe direction ofr;A, FigureY 1.. The -balloonthen carries its nose at a substantial angle to the horizontal and the angle -of attack is near. its maximum. As the velocityvof the wind rises and the lift increases,l link v45 enlongates'as shown in Figure 6. Although the wind continues to blow from the direction shown by the arrow,'the angle. of attack Vand hence the .pull both on the casing and flying wire are reduced.
The v tension of the bowed strut rods exertedfthrugh `the pressure plate 3B pushes in the tail.` .Until *all tensionisV relaxed,4 the aerodynamic'ucharacteristics4 of the balloon are substantially-nun- ,altered This design permits a large changefin volume of gas within the envelope (in aI balloon having the specifications given below, 16%1) `-without, changing the ability'of lthe balloon toy.
,The progressive changein the`position-,ofthe` @strut assembly is illustrated by comparing Figures 1, 6 and 7. 'The `balloon illustrated Vin Figure Tis nearing the end of its flight. f-The struts, now lying in a plane,` hold 'theflns distended but further diiiusion of hydrogen will cause the ns to slacken.
When the iins. slacken, the balloonY maybe hauled down. If no hydrogen is available,-it may be pumped up with air. Obviously, the added'air -does notincrease the existing free 1iftof-theballoon, but it'does restore its aerodynamic flying characteristics so that the balloon may again be flown with the aid of th'eiwind. f A Certain sea rescue balloons also carry an `internally mounted signalling apparatus, the eff ciency of which depends upon the exact maintenance of the angular relation ofthe members. Forjthis purposejtis essentia1 that the cloth forming the envelope iii stretch equally both in Warp and weft directions.
Such apparatus is inserted by placing grommets 63 at accurately spaced locations on the casing i6. VMolded rubber mounting studs 62 are pushedhead ofthe stud 62 is then pushed through the grommet hole. Its `engagement with' the head of the grommet prevents its Withdrawal into the casing. i
In addition to maintaining the angles accurately, a casing whichiiexpands equally imparts another property,. namely, an over-all volumetric increase without altering the iiight characteristics `of `the balloon. For example, a balloon having a casing of rip-stop nylon parachute fabric of Sil-denier warp and iilling weighing one ounce` per square yard and sewn with nylon thread when Afilled with hydrogen to a pressure of four inches (water) had a volume of 40.4 cubic feet. The pressure was increased to 15 inches and the volume increased to 47v cubic feet. Thus the balloon may increase more than 16% in volume Without distortion. The bowed spring tail struts permit an additional volume changefof .at least 19%, as `has been explained. Because the balloon may increasel in volume', it hasa phenomenal ceiling and may be subjected to wide temperature variations.
. The typical sea rescue balloon has the following dimensionsas rigged to signal at the international distress frequency: y i i Length 6' 6" Diameter 3' 3 Wing spread 4l 2" Total Weight of balloon grams `735 Gross lift (at 4" gas pressure) do ""1295 So far, onlyywoven .i nylon and certain `parachute rayons have exhibited th'e necessary uniformity of stretch.
Thirsmballoon is ready foright when the gas ,pressure isILOS inch -of water and the volume is 33.9 cubic :f efet.` vAt this pressure the struts are L straight, asfsh'own in Figure 7. When `the gas jp 4j ss'iiref` reaches 4 inches of water, thebladder ,cornpletely fills the casing andthe struts are bowed, as shownin FigureZ,l andthe balloonhas with a link iiavinglapproximateiy the stressjstrain"characteristics given, this balloon maingand-a-half Vand'fil' miles per hour. Itwill y in `winds of about` tworniles per h'our when the free lift of the balloonalone is but 100 grams and Fthjen will support a flying line weighing 300 grams.
A further example of the spring-pressed volffunie 'adjustment characteristic of the `improved "balloon is shown in the alternative construction illustrated in fFigures 11 to 14, inclusive; This structure is particularly adapted for one man use since' no `partsneedbe fitted together at the time foi launching; [The balloon is Vready for ight as fsoon as itis inflated.V
The envelope'j 'l0 is constructed in the` same V"nianner'asf the envelope I6 and is in fiatedby the bladder 1I, which is' similar to the bladder I8, both of which have been previously described. The balloon isprovided with lifting andz'rudder '112, fare textile'wings sewn to the casing 10 along `certain ofthe V seams 13 between the lunes in such amianner'that when the fins are extended they `lie i n the planeof the'vertical and horizontal axes ofthe balloon 'shownin Figures 13 and 1 4. The
finsare held extended by light strutrods 1 4 which are anchored in suitablepockets l5 andl, which arefsewn to the tipsfof the ns 'l2 and to the envelope `V l0,k respectively; An air pocket is avoided if the strut is placed on th'e lower side of 'l the lifting nsa Loops 11 are sewn on the en# velope VIll-'on the' seams "|3which are intermediate the 'fins 12. `Two elastic links 18 are attached to veach loop'. Theouter'ends of the-links are at i tached to a cable 19 which passes through the pockets 15 and downwardly on the other side of the fm tojoin the opposite elastic link '18. i The arrangement is best shown in Figures 13 and 14. The riggingl) and. itsiattachment to the casing i 1 0 is similar to the `riggingili) which has been pr viously described. Y:- ii hcnithe balloon "is, ri
iiated the struts are gedoutwardly The elastic.links 18 are theref 'oli'eQ stressed and! exert -a counterbalancing push upon the' rods 14 downwardly .towards vthe axis tof the balloon. rAs the gasidiffusesffrom the balloon, the Lrods 'I4 areA progressively pushed further inwards infaman'ner' shown in `Figure A14. Fins "12'` arerigidly extendeduntil the diffusion of ,gas has" progressed'to a' `po`in` t where all tension on th'e .elastic likfirelaxed. If packing in very smalllcompasssunnecessary;'rigid may are not needed.
This system permits large volumetric changes in the gas within the balloon without altering the' balloon to be altered and holds the ns I2 rigidly c extended until the progressive diiusion of the gas has reached a point where all tension of the elastic links 18vhas relaxed (see Figure 14).
. The designs of the balloonswhich have been' described have been most successful. The bal loons have been towed'by .surface craft lat more than 30 knots an hour. They have flown in 45 mile winds and have never recorded line tensions which come neai" the breaking strength of the antenna or the flying line. `They have flown exclusively as kites in winds of one-and-a-half to two miles an hour andhave lifted as much as 933 grams' in winds of tWo-and-a-half miles an hour. The free .lift of the-balloons has been reduced untilonly a tree-top high length of antenna could be supported; even" then the balloons have been launched straight up between trees, have caught the wind'and flown. This makes them have great value in jungle rescue work. They maintain an antenna at a high angle to the horizontal practically independent of wind velocities. Obviously, the design is suitable kfor-larger and more rugged balloons, but it has successfully solved the problem of making` a very light balloon dependable and effective in all weathers but the wildest storm. In addition, the simple bellows-like action of the spring-pressed envelope permits long .continued-flights, which previously could only be ksecured bythe use of more complicated and heavier gas control apparatus.
I'claim: Y l 1. An inflatable kite lballoon comprising a body provided with iins and having, spring means acting on the ns and reacting on the body to maintain the fins extended andcompress the body.
2. A kite balloon comprising an envelope provided with lifting and stabilizing ns andhaving external spring means bearing upon the envelope and responsive to changes inthe volume of gas within said envelope to compress said envelope and. to maintain said ns in an extended position.
3. A kite balloon comprising an envelope and y.lifting and stabilizing fins, and having springpressed means working externally of the envelope to compress said envelope -as the internal pressure falls to maintain the aerodynamic characteristics ofthe balloon.
551m ovoid kite bancari' having lifting and. 4stabilizing ns adjacent the tail and having the tips of said fins lying in a plane forward of the tail, struts having .their outer ends fastened to the tips of said ns bearing upon the tail and normally urgedrearwardly by the internal pres- .1^
sure of said balloony to exerta rearward pull at 'said n tips.
. 6. In a balloon having an inflatable ovoid body,
ythe combination `of opposite vrlnsfonusaid body near `the tail thereof, and a rodhaving its 4-ends anchored to the tips of opposite ns and extending :across the tail of the balloon and urged rearwardly thereby when the balloon is inflated.
7. A balloon. having an inflatable envelope, opposite non-rigid fins flaring-outwardly from said envelope and spring means-between said envelope and'ns responsive to volumetric changes of the envelope and reacting to compressthe envelope `to maintain the fins extended.
'8. An ovoid kite balloonhaving rudder "ns located in the vertical axial plane ofthe balloon and symmetrically positioned above and below the axis, lifting fins located' in the horizontal axial planeiof' the balloon and symmetrically positioned on each side of the axis; strutsfextending between the balloon envelope and the tips of said fins and urged outwardly by-gaspressure within the balloon holding saidy fins extended, and spring tensioned members-to urge said struts inwardly against the balloon.
9. A balloon having an inflatable ovoidbody, outwardly projecting ns located near the tail of said body, and spring means anchored to said ns and engaged and loaded by-the tail when the body is inflated.
10. The combination `of a captive balloon having liftingns capable of sustaining the balloon in moving air and normally presenting the maximum angle of attack to Astill yair, a flying bridle, and spring actuated means responsive to anfincrease in dynamic lift and operative to reduce the angle of attack in proportion to said increase in dynamic lift, thereby limiting the strain` imposed on said bridle and said balloon.
V11. The combination of a captive balloon having lifting ns adjacent its tail surface, a flying bridle attached to the balloon in advance of its center of rotation; a second bridleV attached to the balloon rearwardly lfrom its center ofv rotation and a spring link connecting said rear bridle to a common concentration point, whereby the angle of attack of said balloon is reduced with increasing wind pressure upon said ns.
12, An ovoid captive balloon normally ying with its axis at an angleabove the horizon, having laterally extending lifting ns, a concentration ring lying beneath the body of .the balloon, a harness having forward and rear members connecting the balloon to the concentration ring and spring means interposed in the rear harness member adapted to elongate said member proportionately to an increase in lifting force and `thereby to reduce the angle between the axis of the balloon and the horizon.
13. A kite balloon .having a casingk of woven material capable of stretching along bothiwarp and weft directions to substantially an equal extent, an elastic bladder withinthe casing, and lifting fins capable of imparting aerodynamic lift to said balloon, whereby the gas in said balloon may increase in volumewithout distorting said casing.
14. A kite balloon having an elastic bladderand a surrounding casing, reinforced aperturesprovided in said casing at spaced points on a diameter of said balloon, and anchoringmeans provided on said bladderprojecti-ng through and engaging the. margins of saidfapertures yto x the position cf the elastic bladderwith respect tothe casing.
15. A kite balloon having an elastic bladder and a surrounding casing, reinforced apeijtures provided in said casing at spaced points on a diameter of said balloon, and anchoring means provided on said bladder supporting an internal structure in said bladder and engaging the margins of the apertures to maintain the alignment of said internal structure.
16. A balloon for iiying an enclosed device, having a casing of a Woven material capable of expanding substantially equally in Warp and weft directions, an elastically expansible gas-holding bladder Within the casing containing said device, and angularly spaced elastic suspensions for the device engaging both the bladder and the casing.
l'l. An ovoid captive kite balloon of the nonventing type, having a spring-pressed tail section adapted to compensate for changes in the volume of gas within the balloon.
' DOMINA C. JALBERT.