US2939275A

US2939275A - Solid-fuel rocket type motor assemblies

Info

Publication number: US2939275A
Application number: US412171A
Authority: US
Inventors: Alfred C Loedding
Original assignee: Unexcelled Chemical Corp
Current assignee: Unexcelled Chemical Corp
Priority date: 1954-02-24
Filing date: 1954-02-24
Publication date: 1960-06-07
Anticipated expiration: 1977-06-07

Description

INVENTOR 3 Sheets-Sheet l A. C. LOEDDING SOLID-FUEL ROCKET TYPE MOTOR ASSEMBLIES Af/w/ (hwy/w i June 7, 1960 Filed Feb. 24, 1954 @fiW I ATTORNEY June 7, 1960 A. c. LOEDDING SOLID-FUEL ROCKET TYPE MOTOR ASSEMBLIES 3 Sheets-Sheet 2 Filed Feb. 24, 1954 V INVENTOR 4! red (Jam/dizzy his ATTORNEY June 7, 1960 A. c. LOEDDING 2,939,275

SOLID-FUEL ROCKET TYPE MOTOR ASSEMBLIES Filed Feb. 24, 1954 3 Sheets-Sheet 3 INVENTOR BY @WW /1/1s ATTORN EY Alf/"ed (iLoaZdz'ng United tatcs Patent par SOLID-FUEL ROCKET TYPE MOTOR ASSEMBLIES Alfred C. Loedding, Princeton, N.J., assignor to Unexcelled Chemical Corporation, New York, N.Y., a corporation of New York Filed Feb. 24, 1954, Ser. No. 412,171

6 Claims. (Cl. 60-35.6)

vrality of individual units, said units having the shape of elongated bars of preferably hexagonal contour. Each may be integral from end to end, or may be made of two or more shorter rods abutting end to end and being held together at their abutting ends by a suitable adhe sive. Asa bundle of rods with hexagonal contours cannot fill the entire space of the container in cross-section,.since gaps or spans will be leftcorresponding only to a part of the cross-sectional area of sai d rod s, the gaps oryspaces thus left are filled in by rods which have such a contour. These hexagonal-contour charge rods may be joined by cement extending longitudinally of the charge units; or the charge rods may be slightly spaced from each other and the spaces filled in by a slowerburning powder that also coul d serve as a shock absorber. 1

Also, a basket for the ends of the oharge rods, having pockets of the same hexagonal contour as said rods may behonded or made integral with the end wall, thereby facilitating the completion of the charge and quick insertion thereof into the container.

Finally, the rear end, consisting of a nozzle and a wall secured to the interior of the container and having several safety pressure diaphragrns, said diaphragnis beingdestroyed under a certain pressure, is placed against a yieldingcircumferentialpad of cork or thelike, disposed between "the nozzle supporting wall and the units of the charge. I

The invention will he more fully described hereinafter,

the embodiments thereof shown in the drawings, and the invention will be'fi'nally pointed out inthe appended claims;

In the accompanying drawings, Fig. 1 is alongitudinal central section of the improved motor assembly, taken on line 11 of Fig. 2;

Fig. 2 is an end view, seen in the direction of the arrows on line2--2 of Fig. l; V

Fig. 3 is a transverse section on line 3 3 of Fig. 1; Fig. 4 is a section of a single charge unit, of which i the rocket charge shown in Fig. 3 is composed;

Fig. 5 is a section of a supplementary unit to fill in the circularly disposed' gaps between the hexagonal single units, when said units are arrangedin a cylindrical casing;

Fig. 6 is a section ofthe rear end of the cylinder with the cap secure d therein without the pins shown in Fig.1;

2,939,275 Patented June 7, 19,60

Fig. 7 shows a modified form of having the units spaced and the spaces between said units filled with powder; 7

Fig. 8 is a longitudinal central section of a modified form of the nozzle end;

Fig. 9 is a section of the rear end wall showing a honeycomb form of connection for the charges; and

Fig. 10 is a section along line 10 1 0 of Fig. 9.. In this figure, the end wall has bonded to it a member with cavities into which the charges fit. Instead of bonding this member and the end wall together, they can be integral. 1 I 7 Similar characters of reference indicate corresponding parts throughout the various views of the drawings.

Referring now in more detail to the drawings, a cylindrical shell 10 has its base 11 constructed in the manner shown in Fig. l. A disk 13 of silastic No. 123 such as described in a publication entitled Silastic 'Facts No. 8, distributed by the Dow Corning Corporation, of Midland, Michigan, iibre glass pad, and a front cap 12 of plastic-glass composition are bonded to the shell with epoxy type cement such Epon (trademark) or other good bonding agent, as shown at 13a. The front cap 12 is held by pins 124, preferably made of an aluminum alloy, such as 17 ST described in The Aluminum Data Book .of Reynolds Metals Company, press lit, and bonded epoxy type cement, 2 4 such pins, being usually required.

In place of the pins 12a, tl i e end of the cylindrical shell 10 imay have a conical interior surface, preferably obtained by a conical shim 14 (see Fig. 6), to whioha cap 15 having a conical external surface 16 widened out beyond the thickness of the cap 15 itself to form an exterior flare 17,: is fitted. This camniing resistance obviates the use of the alloy pins 12a shown in Big. 1. section of the cap is of lig'ht weight. The other end of the shell has a nozzle 20 of Dixon crucible hard carbon No. 821 with a bore of smallest diameter at 21 and then gradually flaring outwardly in substantially conical form, at about l0 -15, as shown at 22, and in the other direction flaring inwardly at an angle of about 30-45 with a radius of A as at 2 3, to an abrupt end 24. Dixon crucible hard carbon No. 821 is a carbon electrode material that is pressed and then fused in a high temperature furnace without using a binder. Binders in the nozzle material are undesirable where the material break down must be very low at high temperatures. This nozzle 20 is supported centrally in the shell by a plastic paper tube 25 which cemented to the nozzle 20 and to cap 26. The cap 26 extends from the exterior of the cylindrical tube 25 to the interior surface of the paper ring 38. The cap 26 is provided with a series of openings 28 spaced circumferentially, about four in number, into which safety blowout diaphragms 29 are inserted. The inner side of the cap, 26 is in vided with a wall 30, having a conical inner portion 31 abutting against the conical outside part 32 of the nozzle 20. The space between wall 30 diaphragms 29 is filled by a silastic paste or rubber like material 29d to protect diaphragrns 29 from the heat of combustion. The wall 36 has an outer portion 34 of pointed form. This portion 34 is of cylindrical contour to register with the interior surface 35 of the shell '10, and has a conical inner portion 37. A plastic paper ring bond 38 of flaring inner shape with a cylindrical exterior 39 to; register with the inner surface 36 of the shell 10; extends with said flare along theoutsidfe of the cap 26, and has its innermost outer end of conical shape to register with the conical surface 37 of the member .30; the flaring, interior end registering With a corresponding surfaceAO of the cap 26. A multiplicity of pins 41 enter openings 42 of the shell 10, which openings are circumferenti-ally spaced, being 16 in number in the embodiment shown in Fig. 2. These pins 41 engage the shell openings 42, the tapering nng 38 and the outer ends of the cap 26,

and lock the nozzle in secure position. The pins 41 are of aluminum alloy, haven snug fit and are retained by cotter pins 41a.

Between the nozzle 20 and the solid-fuel charge ends is a space'45 within a cork pad ring 46. The ends of the outer rods 51 forming the charge abut this annular cork pad ring .46. 1

Thecharge 50, as shown in Fig. 3, consists of a plu-' rality of hexagonal units 51, each unit extending the length of the charge from the ring 46 to the barrier or "closing cap 13 (see Fig. 1). r The largest diameter of the unit is 2.20" with 1.90'f across from the flat side to flat side, and the length of the side is 1.10". One charge unit is-16" long, "19 such units being required to fill the internal space" of the container. These charge units 51 The outer units complete hexagonal charge units, they are fitted in with irfiller nnits:57 of the same length (see Figs. 3 and 5) .which have four sides, two sides 58 of 1.10" forming an angle of 120,one side '59 of .333", and the remaining side 60 being arcuate to register with the inner surface "36 of the shell 10. These units57 are one-third of the mam units 51, also 16" long, twelve being required.

Instead of having separate charge units, a honeycomb plastic insert may be provided'of the shape shown in double lines 53 in Fig. 3 and the charges inserted therein. Such honeycomb insert is shown in Figs. 9 and 10.

Ammonium nitrate (NH NO in a rubber-like matrix may be used to fill the space between hexagonal charge units 51, since it is inexpensive and readily available in large quantifies; it releases oxygen only under high pressure, and hence will burn only when the hexagonal charges burn, thus acting both as a fuel and as an inhibitor covering. 7

In Fig. 7 is shown a partial view of the charge in I which the'units 51a are spaced from each other, and

the spacesSlb filled with powder 51c.

A constant burning area is provided. The hexagonal charges may also be made slightly smallerand the spaces of about then filled with NH NO compounded with rubber-like material, to also serve as a shock absorber,

, as mentioned above and as illustrated in 'Fig. 7.

. -The spaces 51]; between the units 51a allow for expansion of the charge units at the ambient temperatures oi-rninus 75 F. to plus 180 F.

The propellant has a restricted burning, and a constant burning area, and belongs to the low pressure constant burning group.

' The ammonium nitrate composition burns uniformly V and dependably with flame produced by primary. charge.

Cement or other adhesive may be used to hold the units in place. 7

In Fig. 8, a modified form of the nozzle is shown. The hollow tube 63 has a nozzle 61 supported by the

members

62 and 64, the outer member 64 being seated circumferentially against the inner surface 63a of the tube 63. At the rear of the

members

62 and 64, a rubber membrane 65 extends from the nozzle 61 to the inner wall 63a of the tube 63. The outer part of the rubber membrane 65 has a sharply pointed wedge 66, and the inner part has an abutment 67 abutting a registering wall 7 68 of the nozzle 61.

In the member 64, a screw threaded bore 69 is provided for the introduction of screw threaded pins 70 which pass through an elongated hole 71 of a plate 72 2 and pass through another elongated hole 711: of a plate The 73, and are then provided withnuts 74. The container wall 63 is reduced internally to form a shoulder 75 against which the plate 73 abuts.

A sleeve 76 having an outer diameter equal to the internal diameter of the reduced portion of the container is fitted into the end ofjthei container 63 to abut against the plate 73' and extends over the plate 72; The plate 73, nut 74, and screw threaded pins 70 are of alumi u alloy. ,7 I

J The. member 64 has diaphragms 81 in its openings 81b which are readily blown out.- The space between diaphragms' 81 and membrane 65 is filled with a silastic paste or rubber like material 81 to protect the diaphragms from the heat of combustion.

Suspended from the plate 73 are plastic paper tubes or solid rods 80 extending radially into the nozzle 61 and through its surrounding sleeve 62, one such tube or rod 80 being provided for each diaphragm in the wall 64. These tubes or rods 80 are intended to neutralize the excessive thrust when diaphragms 81 rupture, and

are then quickly "destroyed. Although they are quickly destroyed by the outflowing flame, the simultaneous drop of the pressure then eliminates the need for these rods. dvantage of this arrangement is that it allows the motor to continue at a reduced thrust, due to the opening in the diaphragm or' diaphragms and the nozzle, which is possible since the novel propellant will operate at any pressure. The walls of the opening of the diaphragm. may be plated with aluminum oxide to prevent their enlargement so as'to realize a practical reduced thrust. Inwardly of the cork annulus 94 is a bag 82 having its closed end suspended from a staple 83. The end of the bag 82 has two stringers or electrical leads 84 which ex- .tend from the bag 82 to a plate 85 through the hole of r 'the, nozzle 61, and their terminals are screwed to said plate 85, as shownat 84a. The plate 85 has radial ex- 40 tensions 85a which areof general U-shape to cup the ends of the nozzle 61 and its surrounding sleeve 62. This cover plate 85 is of plastic and is destroyed by the exhaust gases. The stringers or electrical leads 84 are of electrical conductivity; outside of said plate 85, ignition terminals are provided to ignite the bags 82 which contain an electric match such as manufactured by the Atlas Powder Company, of Wilmington, Delaware and a mixtureof fine powder dust and powder grains. One or two bags may be hooked to the cork annulus. A layer 86 of cloth gauze is treated with loose powder and plastic cement or resin to act as a quick 'match to quicklyignite all hexagonal bar surfaces at the nozzle end of the rocket. Preferably, serrations 87 are provided to evenly distribute the quick match. The hexagonal charges may be joined with ,plastic cloth reinforced with glass cloth or glass flock.

At the bottom of the charges, an annular cork ring 94 is provided, adjacent-the inner wall 63a of container 63.

As mentioned in more detail above, this annular cork ring creates the space between the charge end and the nozzle in which the bag 82, or bags 82, are inserted and attached to said cork ring 94.

' The bottom of the container 63 hasa cap 88 fitted on a reduced end 89 of the container 63. This shell or container 63 is of plastic glass orof an aluminum alloy, and the cup 88 is of aluminum alloy or steel, and is bonded to said reduced portion 89 of casing 63.

All bonding may be done with epoxy type resins or other suitable elements.

The end wall 12 is fitted into the shell 63 and is held by an inward flange 88a of the cap 88.

Fig.9 showsthe bottom end, as described in connection with Fig. 8, but a honeycomb is bonded to the inner surface of the shelladjacentend wall 12. This separate Fig. 10, the honeycomb 90 is shown in front view, with the end wall 12 forming the bottom of the'basket to receive the ends of

charges

51 and 51. This basket has the advantage that'the proper number of charges, complete as in Fig. 4, or partially complete as in Fig. 5, may be inserted and may be seated into the honeycomb basket and be ready for inser tio n into the shell 63 at its rear end and then held bythe bork 94." Any spaces between the charge bars and the honeycomb walls are taken up by coating on said charges. 7

The honeycomb walls are rapidly destroyed, as the flame progresses toward the front end of the rocket; however, the combustion will completely cease before the last several inches of honeycomb will start to fail, and therefore the honeycomb provides sufiicient strength to adequately reinforce the front end wall 12. This honeycomb system obviously solves a severe end closure problem especially for large diameter Jato motors. 'It provides great strength and low weight, with least loss in length to gain the shortest motor. One objective of this entire Jato motor is to create a practical throw-away motor after use, to save time, cost and reduce the danger of introducing flaws as a result of re-using a used article. Therefore, the use of plastic end closures, particularly those that contain both the the nozzle and safety device is novel in this art.

The basket of structural plastic composition with pockets having the shapes of the ends of the charge units, shown in Fig. 10, may be bonded to the end wall, or may be made integral therewith. The depth of the pockets is about 2 inches, this depth being suflicient to securely seat the ends of

charge units

51 and 57. This basket greatly strengthens the end closure and allows a much shorter and lighter end closure.

The shell 10 may be made of a suitable reinforced plastic material, preferably fiber glass (flock or cloth) with which a suitable liner is used to protect it against the intense heat of combustion.

In view of the low operating pressure of the novel propellant, non heated types of aluminum alloys may be used for the shell or as a liner in spite of the low yield strength of 14 to 20,000 pounds per square inch. The advantages of this aluminum non heat-treated alloy are in that the low yield tensile strength will not be affected by the heat but will effectively dissipate the heat due to the high thermoconductivity, thereby rendering a practical and low cost heat resisting liner.

The aluminum may be used as a separate structural element, without the liner, or as a liner in conjunction with reinforced plastic. In either event, since the aluminum is cheaper than the plastic due to the ease of its manufacture and ease of welding or fabricating, the low cost throw-away characteristic is maintained.

The honeycomb structure may also be made of said aluminum alloy (6180), as described in The Aluminum Data Book, 1954 of the Reynolds Metals Company.

It is known that I ato or Ato are terms used to define rocket type motors whose purpose is to assist the takeoff of aircraft and of guided or unguided missiles. This invention is applicable to both types. These types may be used for cigarette restricted type burning or for the internal type of burning. The safety device, nozzle and shell construction would be the same.

The following are the most important advantages of the novel rocket, constructed in accordance with this invention:

(a) Rapid enlargement of the opening after dia phragms rupture due to excessive pressure. This action destroys the closure, this being permissible in view of .the throw-away idea. It provides an excellent safety .rneasure. As before stated, if desired, the rapid enlargement of the opening may be prevented by the use .of the aluminum plating.

(b) When the diaphragm is ruptured, all the flame is (c) The tubes or posts in line with diaphragm holes prevent excessivethrust at the moment the diaphragms rupture. l The particular configuration and arrangement of the charge units is made possible by the use of the novel low-pressure constantly and evenly burning propellant, the underlying invention of which has been filed by me in an application for patent Serial No. 404,717 on Jannary 18, 1954, for Base Propellants and Method of comprising a plurality of adjacent elongated rods each being of substantially hexagonal cross-sectional contour, and a plurality of elongated fragmentary-"units each being of a cross-sectional contour such as to fill the spaces between said rods and the cylindrical wall of said container.

2. In a solid-fuel rocket type motor, in combination: a container having a cylindrical wall and an end wall; a composite charge of solid propellant in said container, the charge comprising a plurality of adjacent elongated rods each having an end adjacent to the end wall of said container and each having a substantially hexagonal cross-sectional contour, and a plurality of elongated fragmentary units each having an end adjacent to the end wall of said container and each having a cross-sectional contour of such shape as to fill the spaces between said rods and the cylindrical wall of said container; and a honeycomb base installed in and adjacent to the end wall of said container, said base defining a plurality of cells for receiving the ends of said rods and of said fragmentary units.

3. In a solid-fuel rocket type motor, in combination: a container having a substantially cylindrical wall and an end wall; a composite charge of propellant in said container and comprising a plurality of adjacent elongated rods each having an end adjacent to said end Wall and each being of substantially hexagonal cross-sectional contour, and a plurality of elongated fragmentary units each having an end adjacent to said end wall and each being of a cross-sectional contour such as to fill the spaces between said rods and the cylindrical Wall of said container; and a honeycomb base defining a plurality of cells for receiving the ends of said rods and of said fragmentary units, said base being integral with the end wall of said container.

4. In a solid-fuel rocket type motor, in combination: a container having a substantially cylindrical wall and an end wall; a composite charge of propellant in said container and comprising a plurality of elongated rods each having an end adjacent to said end wall and each being of substantially hexagonal cross-sectional contour, and a plurality of elongated fragmentary units each having an end adjacent to said end wall and each being of a cross-sectional contour such as to fill the spaces between said rods and the cylindrical wall of said container; a honeycomb base in said container adjacent to said end Wall and defining a plurality of cells for receiving the ends of said rods and of said fragmentary units; and a layer of epoxy type resin between said base and said end wall.

5. In a solid-fuel rocket type motor, in combination: a container having a substantially cylindrical wall, a composite charge of solid propellant comprising a plurality of elongated rods each having a substantially hexagonal cross sectional contour, said rods defining relatively narrow spaces therebetween; a plurality of elongated fragmentaryjunitseach having a cross sectional contonr such as to substantiallyfill the spaces between said rods and the cylindrical wall of said container-, said fragmentary units defining between each other and with the adjacent, rods a pluralityof relatively narrow spaces; 'and' a filler of, propellant in said spaces, said filler being of=slowerburning characteristics than said rods and' said fragmentaryv units... a 6.. In -a solid-fuelrocket type motor, in vcombination: a cylinder having a substantially cylindrical wall; a composite. charge ofvsolid propellant comprising 'a-plurality of adjacent elongated rodsweach'being-of a substantially hexagonal cross-sectional cjonto'ur, each, rod' consisting ofaligned smaller units; alayer of ammonium nitrate in 'a rubber-like matrix between'the smaller units of 'each rod; a plurality of elongated fragmentary units each being of. a .cross-sectional contour :such as, to fill the spacesbetwejemsaidrodsj and the cylindrical wall of said :container, each'ffragmentary unit consisting of .alignedsmaller units; and a layer of ammonium nitrate in a rubber-like matrix between thesmaller units of each fragmentarylunit. r w p t I References Citedin the file of this patent 1 TUNITEDSTATESZPATENTSV' v 2,400,242 et al. May 14, 2,426,526 "j, Rutishauser et al. Aug., 26, 1947 12,478,958 Wheeler et al. Aug. 16,- 1949 r 2,502,458. Hickman t Apr. 4, 1950 j,2,'519,'905, Hickman Aug. 22, 1950 2,603,061 Avery JulylS, 1952 2,605,607 Hickman Aug. 5, 1952 2,623,465 Jasse Dec. 30, 1952 2,703,960 Prentiss Mar. 15, 1955 2,728,295 Rubin et'al. Dec. 27, 1955 2,755,620 Gillot July 24, 1956 2 FOREIGN PATENTS,

12,452 Great Britain Mar 11, 1893 516,865 Great Britain Jan. 12, 1940 3 543,739 Great Britain Mar. 11, 1942 599,275 Great Britain Mar. 9, 1948 Great Britain Apr. 28, 1949

Claims

1. IN A SOLID-FUEL ROCKET TYPE MOTOR, IN COMBINATION: A CONTAINER HAVING A CYLINDRICAL WALL, AND A COMPOSITE CHARGE OF SOLID PROPELLANT IN SAID CONTAINER, THE CHARGE COMPRISING A PLURALITY OF ADJACENT ELONGATED RODS EACH BEING OF SUBSTANTIALLY HEXAGONAL CROSS-SECTIONAL CONTOUR,