US2642238A - All-weather airplane - Google Patents

Description

June 16, 1953 L. c. MCCARTY, JR., ETAL ,612,

ALL-WEATHER AIRPLANE Filed June 25, 1948 5 Sheets-Sheet l 3 rwwvtow LEWIS c- MC-CARTY, JR. HAROLD c. F'ELIO ATTORNEY June 16, 1953 L. c. MccARTY, JR" gq-AL ,642,238

ALL-WEATl-IER AIRPLANE June 25 3 Sheets-Sheet 2 IJMW ORNEY June 16, 1953 c. MCCARTY, JR., EI'AL 2,642,238

ALL-WEATHER AIRPLANE Filed June 25, 1948 z Sh eets- Sheet :5

[LEWIS C. MCCARTY, 1R. HAROLD G. F ELIO ATTORNEY tractable landing wheelsi V wing tips.

Patented June 16, 1953 Xor i N. Y-., assignors to The Marine Aircraft Corporation; New York, N. Y., a. corporation of I New York Application June 25,194s,-seriar-Nmsmw 21 claims; (01. 244 101) This invention relates to? airplanes generally, and includes certain-features particularlyapplicable to amphibians; and flying boats. The plane of this invention is-provided with:- a; pneumatic cushion formingthe lower part of the hull or fuselage, and withinfiatable' cushions on either side of the fuselage or hull (in addition-to the usual ailerons or spoile'rshthe'se lateral inflatable' cushions acting to maintain lateral st'a bility' at rest, and in landing and takeoff-operations. The plane "of this inve'nti'on will alight on and take off from land*,-wat.er,- water containing floatinglica -and from. snow'o'r ice surfaces.

Further objects, features and advantages of the inventionarez' 3 1.'To provide an improved pneumatic bottom for the fuselage made of tough. resilient, air tight material which may beinflated: to the necessary pressure for'absorbing-the shocks of land- 7 ing whether on land, :water, snow or ice.

2. To provide a'l'andi'ng-cushion as just described with inset wells in which are housed "re- The I construction is such thatthe plan m'ay alight. safely on: land or water with the landing wheel's either up or down,

. as will be more fully described later.

3-. To provide; oneach side-ofthe' fuselage an inflatable pneumatic landing cushion. These lateral landing cushionszea-ch comprise a flap pivoted near the trailing edge of the wing, and a sheet of air tight, resilient material positioned on the underside of th'e wing-and secured at its trailing: edge tothe trailihgedge of the flapysuch assembly being -air= tightand" inflatable for providing landingcushions.- These cushions provide hydrodynamic planing 'surfaces' and hydrostatic displacement members for maintaining transverse stability at rest-and landing-and takeoff operations. In normal flight; these pivoted flaps are streamlined with-- the wing and the flexible sheet material is flushwith the under surface of the wing so that the wing is of normalcont'our in flight. When pivotedfldownwardl-y-i they' would also'h'ave a brakingefiect witlrincrased lift.

4. The wings of the lane' outwardly of said lateral landing 'ciishitifisare mime-a upwardly at adihedral angle to -avoid contactwith" a landing surface.

5-. Lateral stability-of'the plane is achieved by the use of thetusuakailerons; where the; landing'cushions' do not extendv all the. way to the However; in amodifiedl form-,. the lateral cushions-may extencl'rito, or nearly to; the.- wing tips,;in;which.=case lateral:- control: is achieved:- by the 1 use of? the: spoilers: well known: in the art, on the upper surfaces 01 the wings.

6. The main landing cushion, below the bottom of the; fuselaget'is' formed of tough, resilient, flexible air tight material secured at its outer edge to the hull ortus'elage, from the nose well aft toward the t'tail. These" outer edges. are secured to: thafuselag or hu ll atvith'e chine" line and contrary to? the usualrpracticepthe topofv the main landing cushion is not 'form'e'd of-this sheet of flexible? material, but is? formed by the floor of the fuselage. The floor of the fuselage is preferably provided withtwor sets: of valves, spring loaded; for relieving?v excess pressure in' thegm'ain landingcushi'on in: the event of a hard landing, the other SetJpassiIigairF under pressure from the pressurized fuselage into the several; compartments ofrthe-mainxlanding. cushion for keeping them properly inflated;

'7. The: maimlandin'gi'cushion-as well as the laterallan'ding cushionsimay' be compartmented, that is,: may beprovidedwith fore and aft as well as: lateral part'itions; thereby providing. separate compartments" fort maintaining air pres-'- sure; in the remainings compartments. in the event of: a? punctureif of a: particular compartment.-

8. The airplane of this'invention': isipreferably' providediwihxa'i piston" engine forfdri-ving-ltheusual propeller, 'and 'withi'a jet engineer-known:con-

as the two later 45' struction: The exhaust gases from the piston engine are piped: to? the f j et' engine; 7 such exhaust gases not only keep the jet wa'rmed up; i but also drive-the blower'of the jet; Air compressed by this blower is led to the piston-engine for-super charging it.: In" other Words; the 'jet" engine, under-certain conditions-, acts as an exhaust driven supercharger. The jet engine-is thus 'always kept warmed up arid so is a v 'ailalcfle to sup ply additional poWefi-hstarifly; asmay be needed for take off' and combat operationsl 9. Compressed air from the blower of thejet engine may also be used 'to pressurize the cabin, and to-infla-teth cushions-err either sid'e or the minor fuselage.

furtheradvantagesof structureand operation;

will be described in connection v v with the accom pan ying: drawings, whei-'eirit Fig. lzisia front view-of an' airplane according to this, inventioni .1 sa si'devi'ewof 'tlie same.

fi -.3 span views a Fig. 4 'is a cross-section, On an enlarged seale;

Fig. is a cross-section, on an enlarged scale, taken on the line 5-5 of Fig. 3.

Figs. 6 and 'I are longitudinal and transverse cross sections through the wells for the landing wheels.

Fig. 8 is a cross-section, on an enlarged scale, through the floor of the fuselage or hull.

Fig. 9 is a plan view of a portion of a wing, showing a modification.

, Fig. 10 is a diagrammatic view of a jet engine and cooperating parts.

Fig. 11 is a fragmentary front view, enlarged, showing one of the lateral landing cushions in inflated position. 7

Referring now to these drawings, the airplane comprises the fuselage or hull 2 in which is housed one Or more engines for driving the usual propeller 4. The wings 6 extend outwardly from the fuselage in the usual way, the outer portions 8 being angled upwardly at a slight dihedral angle. These wings may be provided with the usual landing wheels I0 foldable into the respective wings. I

Secured to the under side of the fuselage or hull 2 and extending from the nose well aft toward the tail is a sheet of tough, resilient, flexible, air tight material I2, treated with rubber or synthetic resin, the outer edges IA of this sheet being secured air tight to .the hull at the chine line I6 thereof. The hull 2 is provided with a floor I8 which cooperates with the flexible sheet I2 to form an air cushion hereinafter referred as theair cushion I2. Contrary to the usual practice, the top of the air cushion I2 is not formed of resilient material, such top being formed by the floor It of thefuselage, thereby saving that much weight.

The cushion I2 is provided with one or more longitudinally extending resilient keelsons or partitions 20 made preferably of thick heavy rubber or the like which will bend on impact and which provides longitudinal compartmentation.

The cushion I2 is also provided with a number of lateral partitions 22 for providing lateral compartmentation, thereby localizing possible loss of air in, a punctured compartment to such punctured compartment.

'28 housed in these wells are of the retractable type having the usual shock absorbing cylinders 30.

As shown in dotted lines in Fig. 2, the wheels 28, even in retracted position, extend a small distance below the outer surface of sheet 12 so if the plane should encounter a slight rise in landing, the plane, even with the wheels up, will be given a lift over such obstruction. With this construction, the plane will alight on land, water,

snow or ice, with the wheels either up or down,

thereby minimizing the possibility of accidents.

The lateral landing cushions, forming an important feature of the present invention will now be described:

These landing cushions, indicated generally at 32, are each formed by a flap 34 pivoted at 3B near the trailing edge of each wing and extending outwardly from either side of the fuselage at a substantial distance from the wing tips. A sheet of tough, resilient, flexible material 38 has its leading edge 40 secured to the under surface of wing 6 and its trailing edge to the trailing edge of the flap 34. End walls 44 are provided for completing an airtight landing cushion, which is shown in extended and inflated position in Fig. 5. Sheet 38, instead of terminating at 40, could be reversed at 40 and continued back wardly against the underside of the wing, to complete an air tight bag or balloon. When so infiated, the cushion extends a sufficient distance below the wings for engaging the landing surface, such as water, snow, ice and the like, and serves to prevent the wings from engaging such surface, such clearance being further achieved by the upwardly angled parts 8 of the wings. These landing cushions when inflated and in extended position, as in Fig. 5, ride along on the landing surface and serve to maintain lateral stability; if the plane is landing on water, they displace a certain amount of water, thereby further maintaining lateral balance in landing and take-01f operations, and also maintain lateral balance when the plane is at'rest.

When deflated, flap 34 would be coincident with the trailing edge of the wing, as in Fig. 5, sheet 38 would be tight against the underside of the wing, so that in normal flight,'the normal contour of the wing would be maintained.

When extended, these cushions would also have a braking effect. In normal flight lateral control is maintained by the usual ailerons 50.

In a modification of the invention, as shown in Fig. 9, the lateral landing cushion 42 may extend substantially to the wing tips, in which event lateral control is maintained in normal flight by the use of spoilers 45 on the upper surface of the wings, as well known in the art.

Air under pressure is supplied tothe compartments of the main landing cushion I2 and to the lateral cushion 32, in any desired manner. Such air may be supplied from any suitable compressor, by valved pipes connected to the respective compartments. A separate air supply is provided for each compartment for maintaining air pressur therein, even if a particular compartment is punctured.

In one aspect of the invention, the main body of the hull, above the floor I8 may be pressurized, as is well understood in the art, and the floor may be provided with spring loaded valves 52 opening upwardly into the fuselage and with a second set ofspring loaded valves 54 opening downwardly into the main air cushion I2. A series of valves of this type may be used, one set for each compartment in the main air cushion I2. In the event of a hard landing, the upwardly opening valves 52 would open, relieving excess pressure and preventing rupturing of the sheet I2. Sheet I2 would also bulge upwardly, as in dotted lines in Fig. 4. Where the cabin is pressurized, the air pressure is maintained therein so that valve 54 would open and allow such air under pressure to enter into the various compartments in the main cushion I2.

In one aspect of the invention, the amphibian may be provided with a jet engine 60 of known construction, illustrated diagrammatically, mounted in the tail of the fuselage, the exhaust outlet 62 from said engine'being at the extreme rear end of the fuselage. Such a jet engine normallycomprises one or more blowers or fans.

engine.

The blower compartment 6.4 of: the.v jet: engine; is

sure for inflation purposes as above. mentioned and for supercharging'the main engine thru pipe ll; In other words, the jet. engine operates: as an exhaust operated supercharger for the;- piston The jetengine is thereby kept warmed up for supplying additional powerwhen needed, especially for take-off and; combat operations.

Air taken in by the suction slot' T42 may: be supplied to the jet: engine: where another type of slot is used, in which air under pressure is passed through a wing sl'ot tothe top, rear surface of the plane; the blower of'the jet engine may be used to supply air to the pressure; slot, especially where the lateral inflatable landing cushions would tend to blanket the normaluse of such pressure slots, where air under pressure passes upwardly through such slot.

Instead of or in addition to a jet enginein the tail of the plane, a jet engine may be mounted in the trailing edge of the wing, directly behind each of the usual piston engines: Th'ehousings for these jet engines may be in eifect a rearward continuation of the nacelles of'the piston engines with whichthe respective jet engines are associated. These jet engines also act as: exhaust operated superchargers for the respective piston engines, and'they may al'sobe used to-supply air under pressure for the main and lateral in:- flatable cushions.

Many features of the present invention are applicable to aircraft in general, whether land planes, amphibians or'flying boats, and accordingly-the terms fuselage, hull,nacelle and the like are used in anillustrativeanddescriptive sense, and not ina restrictive sense.

Whilethe invention has been" described in some detail, it should be understood"that the'invention is not to be restricted to the details 'illustrated, but may be carried out inrother-waysi We claim as our invention:

1. An airplane, comprisingafuselageprovided with a floor, aflexible, tough, airtightfabric having its outeredges secured'to thefuselage, said fabric being positioned below the floor-and extending from the noseof the fuselage aft well toward the tail, said fabriccooperating-with said floor to form an air tight chamber; the top of which chamber is-formed by .said'fioor; a: pair of pivoted flaps. carried by: the wings-'of'theairplane, one on each side of the fuselage-, and tough, airtight flexible material positioned on the underside of the wing, ahead of each fla and secured to thetrailing'edge of-each flap, for forming inflatable resilient air tight cushions :for

maintaininglateral balance in --landing:-and tak'e trailing: edge thereof air tight flexible: material positioned on the: underside of each. wing, ahead I of each flap, and attached to the trailing: edge of said flap, and: cooperation with its; respective flap to form inflatable air tight: cushions. providing hydrodynamic planing surfaces and hydrostatic displacement members for maintaining transverse.- stability. in landing and take-off. operations. andv at rest; ,7

3. An airplane, comprising a fuselage provided with a. floor, a flexible, tough, air tight fabric having its outer edges secured to the fuselage,

said; fabric being: positioned below the floor and extending from. the. nose oft the fuselage aft well towar'clj thetail, saidifabric-cooperating with said floor to form an airtight chamber, the top of which chamber is formed by said: floor, av pair of' pivotedflapscarried by the wings of the airplane; one on each: side of thefuselage; and

tough, air tight. fabric positioned ahead of" each flap and attached to the: trailing edge: of each flap, for forming: inflatable resilient air tight 7 cushions. for use inv landing andf take-off operations, the wings of said airplane, outwardly of said pivoted flaps, being. angled upwardly for clearing: the: landing surface.

fabric being positioned below the flbor and extending from the nose of the hull aft well toward the tail, said fabric cooperating withsaid floor to form amai'rtight chamber, the top ofwhich chamber is formediby saidfloor, a pair of'pivoted ifi'apSf camiedlby the wings of the place; one on each sideof' the hull andinset from the trailing edge thereof, asheet of'tough', airtight; flexible material positionedon the underside of each wing. ahead" of each flap and attached to the trailing edge of said flap, and. cooperating with its: respective flap to form inflatable air tight cushions providing hydrodynamic planing surface and' hydrostatic displacement: members for maintaining transverse stability at rest and in landing:and take off'operations, the wings of said fiyingiboat, outwardly:of-"saidpivoted flaps, being angledupwardly for clearing the landing surface.

5; Anairpl'aneg: 'comprising'afuselageprovide'd with a floor, aflexible; tough, air tight fabric having its outer edges secured to the fuselage; said fabric being positioned below the floor and extending from the-"nose of thefuselage aft well toward thel tail, said fabric cooperating with said floorto form an air tight chamber, thetop of which chamber is'formed b y 'said floor, a pair of pivotedeflaps: carried by the wings of the airplane,v oneon' each side ofthe fuselage, tough,

air tight fabric positioned on. the underside of "each wingyahead of each flap, and securedto' the trailing edge :of each 1 flap,- for forming; inflatable resilient: air tight cushions for'maintaining lateral stability at 1 rest and inilanding and take-off operations; and ailerons carried b'y the' wings of pivoted flaps carried by the-wings of the airplane, 'onelon :each :side .of-ztheefuselagaitough; air atight fabric secured to the plane ahead of each flap and to the trailing edge of each flap, for forming inflatable resilient air tight cushions for use at rest and in landing and take-off operations, and spoilers for lateral balance carried by the upper surfaces of the airplane.

7. An airplane, comprising a fuselage provided with a floor, flexible, tough, air tight fabric having its outer edges secured to the fuselage, said fabric being positioned below the floor, said fabric cooperating with said floor to form an air tight chamber, the top of which chamber is formed by said floor, a pair of pivot-ed flaps carried by the wings of the airplane, near the trailing edges thereof and extending for substantially the full length of the wings, air tight flexible material, secured to the underside of each wing, ahead of its flap, and having its rear edge secured to the trailing edge of its respective flap and cooperating therewith to form flexible, inflatable, resilient cushions providing hydrodynamic planing surfaces and hydrostatic displacement members, and spoilers carried by the upper surfaces of the wings.

8. An airplane comprising a fuselage, a pneumatic inflatable landing cushion on the underside of the fuselage, pivoted flaps carried by the wings of the plane, near the trailing edges thereof, and flexible, air tight sheet material cooperating with the underside of the wings and positioned below said pivoted flaps, for forming flexible, air tight, inflatable cushions just ahead of the flaps, for providing when inflated hydrodynamic planing surfaces and hydrostatic displacement members adapted to contact landing and take-ofl surfaces for maintaining transverse stability in landing and take-off operations.

9. A flying boat, comprising a hull, a pneumatic inflatable landing cushion on the underside of the hull, pivoted flaps carried by the wings of the flying boat, near the trailing edges thereof, and flexible, air tight sheet material cooperating with the underside of the Wings and positioned below said pivoted flaps, for forming flexible, air tight, inflatable cushions just ahead of the flaps, for providing when inflated hydrodynamic planing surfaces and hydrostatic displacement members adapted to contact landing and take-off surfaces for maintaining transverse stability at rest and in landing and take-off operations, said sheet of flexible material, when the cushions are deflated, being flush against the underside of the wing, while its cooperating flap is coincident with the trailing edge of its wing.

10. An airplane, comprising a fuselage, a pneumatic inflatable landing cushion on the underside of the fuselage, said cushion being provided with inset wells, landing wheels housed in said wells, pivoted flaps carried by the wings of the plane, near the trailing edges thereof, and flexible, air tight sheet material cooperating with the underside of the wings positioned below said pivoted flaps, for forming flexible, air tight,

inflatable cushions just ahead of the flaps, for

providing hydrodynamic planing surfaces and hydrostatic displacement members adapted to contact landing and take-01f surfaces for maintaining transverse stability in landing and takeoff operations.

11. A flying boat, comprising a hull, a pneumatic inflatable landing cushion on the underside of the hull, ailerons carried by the wings at the ends thereof, pivoted flaps pivoted near the trailing edges of the wings, and positioned between :the ailerons and the fuselage, andflexible, air

'8 tight sheet material cooperating with the under side of the wings and positioned below said pivoted flaps, for forming flexible, air tight, inflatable cushions just ahead of the flaps, for providing hydrodynamic planing surfaces and hydrostatic displacement members adapted to contact landing and take-off surfaces for maintaining transverse stability in landing and take-off operations.

12. An airplane, comprising a fuselage, a pneumatic inflatable landing cushion on the underside of the fuselage, spoilers carried by the top surface of the wings for lateral balance, flaps pivoted near the trailing edges of the wings, and flexible, air tight sheet material cooperating with the underside of the wings and positioned below said pivoted flaps, for forming flexible, air tight, inflatable cushions just ahead of the flaps, for providing hydrodynamic planing surfaces and hydrostatic displacement members adapted to contact landing and take-off surfaces for maintaining transverse stability in landing and takeoff operations.

13. A flying boat, comprising a hull, a pneumatic air tight landing cushion on the underside of the hull, the outer parts of the Wings being angled upwardly at a dihedral angle, flaps pivoted to the wings, between said dihedral angle and the hull, near the trailing edges of the wings; flexible, air tight sheet material cooperating with the underside of the wings and with respective flaps, for forming flexible, inflatable cushions just ahead of the flaps, said sheet material, when the cushions are deflated being flush against the underside of the wings, while its cooperating flap is coincident with the trailing edge of the wing, said cushions providing, when inflated, hydrodynamic planing surfaces and hydrostatic displacement members for maintaining transverse stability in landing and take-off operations.

14. A flying boat, comprising a hull, a pneumatic air tight landing cushion on the underside of the hull, said cushion being provided with inset wells, landing wheels housed in said inset wells, the outer parts of the wings being angled upwardly at a dihedral angle, and provided with ailerons, flaps pivoted to the wings, between said dihedral angle and the hull, near the trailing edges of the wings; flexible, air tight sheet material cooperating with the underside of the wings and with respective flaps, for forming flexible, inflatable cushions just ahead of the flaps, said sheet material, when the cushions are deflated being flush against the underside of the wings, while its cooperating flap is coincident with the trailing edge of the wing, said cushions providing, when inflated, hydrodynamic planing surfaces and hydrostatic displacement members for main taining transverse stability in landing and takeoff operations.

15. An airplane, comprising a fuselage, pivoted flaps carried by the wings of the plane, pivoted near the trailing edges thereof, sheet material positioned ahead of said pivoted flaps, and secured to the trailing edges of the flaps, for thereby forming inflatable, air tight landing cushions, providing when inflated, hydrodynamic planing surfaces and hydrostatic displacement members for maintaining transverse stability at rest and in landing and take-off operations.

16. A flying boat, comprising a hull, pivoted flaps carried by the wings, pivoted near the trailing edges thereof, sheet material positioned ahead of and below said pivoted flaps, and secured to the flaps, for thereby forming inflatable, air tight landing cushions, providing when inflated, hy-

drodynamic planing surfaces and hydrostatic displacement members adapted to contact landing and take-off surfaces for maintaining transverse stability in landing and take-off operations, said flaps, when folded, coinciding with the trailing edges of the wings, with said sheet material flush against the underside of the wings.

for maintaining transverse stability at rest and in landing and take-01f operations, and flaps,

chamber providing a pneumatic cushion, for

alighting and take-off on land, water, snow or ice, and differential valve means positioned in said floor for passing air in either direction between the pressurized fuselage and said air tight chamber, when the airpressure-in one exceeds the air pressure in the other by a predetermined amoiuit.

when folded, coinciding with the trailing edges of the wings, with said sheet material flush against the underside of the wings, the wings of the plane, outwardly of said pivoted flaps, be"- ing angled upwardly for clearing the landing surface.

18. An amphibian airplane, comprising a fuselage, pivoted flaps carried by the wings of the plane, pivoted near the trailing edges thereof, sheet material secured to theunderside of the wings, ahead of said pivoted flaps, and secured at its trailing edge to the trailing edges of the flaps, for thereby forming inflatable, air tight landing cushions, providing when inflated, hydrodynamic planing surfaces and hydrostatic displacement members for maintaining .trans--' verse stability in landing and take-off [operations, said flaps, when folded, coinciding with the trailing edges of the wings, with said sheet material flush against the underside of the wings,

and spoilers carried by the upper wings of the plane, for lateral control.

19. An airplane, comprising a pressurized fuselage provided with a'floor, a flexible, tough, air tight fabric secured to the fuselage, said fabric being positioned below the floor, said fabric cooperating with said floor to form an air tight chamber, the top of which chamber is formed by said floor, such chamber providing a pneumatic cushion for alighting and take-01f on land, water, snow or ice, and valve-means positioned in said floor for passing air from the pressurized fuselage into said air chamber for inflating it.

20. An airplane, comprising a pressurized fuselage provided with a floor, a flexible, tough, air

tight fabric secured to the fuselage, and positioned below the floor thereof, said fabric cooperating with said floor to form an air tight chamber, the

Number top of which chamber is formed by said floor, such 21. An airplane, comprising a fuselage, pivoted flaps, carried by the wings, and pivoted near the trailing edges thereof, sheet material, secured to the underside of the wings, ahead of said flaps, and also secured to the flaps, for thereby forming inflatable, air-tight cushions, providing when inflated, hydrodynamic planing surfaces and hydrostatic displacement members wherein said sheet material contacts the landing and take-off surfaces, said displacement 1 members. serving to maintain transversestability in landing and takes-off operations.

LEWIS C. MCCARTY, JR. HAROLD G. FELIO.

References Cited in the file of this patent UNITED STATES PATENTS Name Date 1,069,694 Hayot Aug. 12,1913 1,489,619 Tsavaris Apr. 8, 1924 1,617,816 Loening Feb; 15, 1927 1,643,049 Black Sept. 20, 1927 1,748,492 Mikula Feb. 25, 1930 1,866,451 Carden July 5, 1932 1,890,553 Young Dec. 13,1932 1,930,922 Burnelli Oct. 17, 1933 1,944,436 King Jan. 23, 1934 2,011,902 Leigh Aug. 20, 1935 2,023,312 Sev'ersky Dec. 3, 1935 2,085,761 Lysholm July 6, 1937 2,110,865 Burgess Mar. 15, 1938 2,127,871 Kozlofi Aug. 23, 1938 2,160,281 Price May 30, 1939' 7 2,173,273 Seversky Sept. 19, 1939 2,340,396. McDonnell Feb. 1, 1944 2,349,584 .Arnstein et al. May 23, 1944 2,365,205 Martin Dec. 19, 1944 2,391,326 McKinley Dec. 18, 1945 2,393,713 Shoults Jan. 29, 1946 2,411,227 Planiol et a1. Nov. 19, 1946 2,431,592 Stalker 1 Nov. 25, 1947 FOREIGN PATENTS Number Country Date 193,005 Great Britain Jan. 17, 1924 642,353 'Germany Mar. 2, 1937 840,739

France 1 Jan. 23, 1937

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