US3378216A

US3378216A - Integral fin canister-nozzle exit cone

Info

Publication number: US3378216A
Application number: US546448A
Authority: US
Inventors: George K Oss; Danny D Dunfee; Roland C Webster
Original assignee: SUSQUEHAMA CORP
Current assignee: SUSQUEHAMA Corp
Priority date: 1966-04-29
Filing date: 1966-04-29
Publication date: 1968-04-16
Anticipated expiration: 1985-04-16

Description

April 16, 1968 G 055 ET AL 3,378,216

INTEGRAL FIN CANISTER-NOZZLE EXIT CONE Filed April 29, 1966 GEORGE K 035 DAN/V) D. DU/VFEE ROLAND C. WEBSTEI? BY gM AGE/V T INVENTORE United States Patent INTEGRAL FIN CANTlSTER-NOZZLE EXIT CONE George K. Oss, Springfield, Danny D. Dunfee, Fairfax County, and Roland C. Webster, Annandale, Va, as-

signors to The Susquehanna Corporation, a corporation of Delaware Filed Apr. 29, 1966, Ser. No. 546,448 7 Claims. ('Cl. 244-334) ABSTRACT OF THE DISCLOSURE This invention relates to an integral fin and nozzle expansion cone assembly for a rocket wherein the expansion nozzle is used as a support for the fin canister and both the nozzle expansion cone assembly and the fine canister are removable and changeable.

The ability of a rocket to maintain its predetermined trajectory is dependent, in large part, upon the aerodynamic design of the rocket casing and the placement and efficiency of its stabilizing fins. For example, a factor greatly alfecting overall rocket performance is the design of the exit cone, for it is by this means that the expansion of the motive gases is con-trolled in great part. The expansion cone is generally designed for the atitude range at which the motor will do most of its operating; for example, if the rocket is meant to be boosted to high altitude before main motor ignition one type of cone is preferable, while in the case of a rocket with low-altitude ignition it is advantageous to use an expansion cone which is specifically designed for low-altitude flight. In the past, and as evidenced by the prior art, the practice was to design each rocket structurally and aerodynamically specifically to match the qualifications and parameters required for a particular task. This was acceptable in the days when rockets were manufactured in small numbers in comparison with today, but with more widespread use there came a demand for increased versatility and lower costs per unit. It is now advantageous for the rocket manufacturer to produce and stock a minimum number of standarized rocket motors, casings, and air-frames, and to rely upon changes in accessory components in order to vary operating characteristics. For this reason there exists a demand to provide for a maximum interchangeability of parts and accessories in order to enable this minimum number of shelf items to perform the maximum number of tasks.

Considering the specific problems encountered in the design of fins and nozze expansion cone assemblies, and in line with the aforementioned desires, the instant invention provides a new and simple means for providing a basic rocket motor and air-frame design with a maximum of versatility by providing an easily interchangeable fin and nozzle expansion cone assembly. It is well-known in the art that installation of the stabilizing fins far back on the rocket vehicle adds to stability and that a reduction in aerodynamic drag is provided by a smooth contour throughout the length of the rocket. In addition, as the distance from fin to vehicle center of gravity is increased, the size of the fin can be decreased and still provide the same degree of stabilization. By the teaching of the instant invention the stabilizing fins are mounted as far aft as is possible on the rocket vehicle. The design also eliminates a usual component by using the expansion nozzle as the rear fin support. By the construction of the instant invention, both the nozzle expansion cone and fin canister are removable and changeable, allowing substitution of t 3,378,216 Patented Apr. 16, 1968 to fins having particular aerodynamic characteristics. By combining, in an integrated, interchangeable structure, a set of stabiizing fins and -a nozzle cone which have been matched to a particular set of parameters, the instant invention provides a means by which a basic rocket motor and air-frame may be quickly and easily tailored to a specific task.

It is the primary object of the intsant invention to provide an improved integral fin and nozzle expansion cone assembly for rockets.

Another object of the invention is to provide a improved fin assembly which contributes to the aerodynamic stability and reduces the drag of the rocket vehicle.

Still another object of the invention is to provide an integral fin canister and nozzle expansion cone assembly in which the expansion cone is removable and interchangeable.

An additional object of the present invention is to provide a fin assembly in which the size and weight of the fins and the mounting elements are kept to a minimum.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description When considered in conjunction with the accompanying drawing wherein:

FIGURE 1 is a perspective view showing the integral fin and expansion cone assembly of the invention in position for mounting on the rocket casing;

FIGURE 2 is a side elevation, partially in cross-section, showing in detail the elements of the instant invention; and

FIGURE 3 is a side elevation, partially in cross section, of an alternate embodiment of the expansion cone of the instant invention.

In FIGURE 1 there is shown the main body 10 of a rocket including the air-frame and rocket motor, with the improved integral fin canister and nozzle expansion assembly 11 sohwn in position for attachment to the main body 10. Assembly 11 consists of a fin canister 12,

fins

13, 14, 15, and 16, and an expansion cone, which is not visable in the view.

In FIGURE 2 the elements of the inst-ant invention are shown in detail. A motor case 19 of any standard design has a terminal portion 20 which contains nozzle insert 21, also of design known in the art. It is to the terminal portion 29 of the rocket motor case that the integral fin and expansion cone assembly 11 is attached. Forming the nucleus of assembly 11 is a truncated cone-shaped adapter element 22, the design of which is complementary in shape to the terminal portion 20 of the motor case. This adapter element 22 is provided with a threaded portion 24 at the end having a minimum radius and with a plurality of holes along the sides through which screws 23 are passed in order to mate the adapter element to the motor case. Expansion cone 17 is preselected to provide the proper degree of expansion and is provided at its forward end with a threaded portion 25 by means of which it will screw into adapter element 22. Expansion cone 17 is also provided at its forward end with a sealing means such as an O-ring seal 26, which will preclude the escape of propulsion gases between it and the end of nozzle 21, but this O-ring seal '26 could also be installed in the rear portion of adapter element 22.

As aforestated, it is desirable to mount the stabilizing fins as far rearward as is possible, for this contributes to the aerodynamic stability of the vehicle and also, since the fins are a greater distance from the vehicles center of gravity, it allows for the use of smaller fins to maintain the same stabilization influence, thus saving weight and expense.

Pins

13, 14, 15, and 16 are most desirably mounted by fixedly attaching them to a fin canister 12 by any conventional means such as a plurality of welds 18. In order to preserve the streamlined shape of the rocket vehicle, fin canister 12 is preferably of the same outside diameter as motor casing 19, and thus no undesirable flow effects are created in the area of the fins. In the preferred embodiment the largest diameter of the expansion cone is equal to the inside diameter of the fin canister, so that the streamlining of the vehicle may be maintained, although larger expansion cones may be used. The use of a large cone having an end diameter greater than that of fin canister 12 results in a portion 30 of the cone breaking the aerodynamic continuity of the vehicle at a sacrifice in desirable flight characteristics. However, if the vehicle is boosted to operating altitude, these undesirable characteristics are minimized. If it is desired to use an expansion cone which allows less expansion of gases, that is, one which has a smaller exhaust diameter such as is used at low altitudes, to be in keeping with the present invention such a cone is equipped with an outside flange 29 which increases its final outside diameter to that of fin canister 12. Such a construction is shown in FIGURE 3. The reason for this will be explained hereinafter when the method of assembly of the various components is discussed. Fin canister 12 is equipped in its forward portion with a plurality of screws 27 which are adapted to fit into cooperating holes in adapter element 22 in order to attach the fin canister thereto. As for the rear mounting of the fin canister, it is accomplished by means of a plurality of set screws 28 which are tightened down to engage flange 29 on the expansion cone 17.

The elements of the instant invention may be assembled as a unit and then installed on the rocket case or they may be placed piece by piece on the vehicle. The first step of unit assembly consists or attaching together adapter element 22 and the preselected expansion cone 17 by means of their

screw threads

24, 25 respectively. Then the fin and canister assembly is slid over the adapter plate and expansion cone such that screws 27 may properly engage adapter element 22 and the forward end of the fin canister is thereby fastened. This will place set screws 28 on the rear portion of fin canister 12 in alignment with flange 29 of the expansion cone 17, and the tightening of these screws provides rear support for the fin canister while also locking expansion cone 17 against rotation on threads 24-. The final step in this mode is to install the integral assembly on the rocket air-frame 10 by slipping it over the nozzle cone on the terminal portion 20 of the motor casing 19 and then attaching it by means of screws 23 to threaded holes in the rocket casing.

In a second method of assembly the adapter portion 22 is first placed about terminal portion 19 of the motor casing and attached thereto, and the expansion cone is then screwed on. In the final step the fin canister assembly is slipped over both adapter and cone and fastened by screws 27 and set screws 28. The importance of flange 29 on the expansion cone 17 is now seen, for it is by means of this flange that rigidity is given to the entire assembly; the rear of the fin canister is supported and the expansion cone 17 is locked against rotation. For this reason it is preferred that each expansion cone used in the invention, no matter what the exhaust opening diameter, be extended by means of a flange such that the final outside diameter is substantially equal to the inside diameter of fin canister 12, thus allowing the locking action by set screws 28. The elements of the integral fin canister expansion cone assembly may be preassembled and shipped separate of the rocket air-frame 10 to be assembled some time prior to launch as a unit, or these elements may be installed one by one onto the rocket. Once the unit has been installed on the rocket vehicle it is still possible to effect a change of expansion cone by simply loosening set screws 28, unscrewing the expansion cone from the adapter plate, and replacing it with a new one. Thus, the user is able to make last-minute changes in the field, if necessary. The same sort of last-minute iutertlhangeability also applies to the fins and fin n swr.

It is thus seen that the instant invention provides a simple, efiicient, and reliable means for attaching any one of the preselected designs of nozzle expansion cones and stabilizing fins in order to best match the desired vehicle flight characteristics, operating parameters, and operating altitude. In addition to providing means for quick field change of expansion nozzle and fin components when it is desired at the last minute to change the operating altitude or flight characteristics of the rocket vehicle; the concept of the instant invention facilitates easy packing and shipping of rocket motor casings and associated components since the expansion cones and fins can be shipped separately and easily installed immediately prior to use.

The number of designs of nozzle expansion cones and fins that can be adapted for use with the instant inventive concept is great, and it is not the intention to restrict them to the designs shown in the drawing. Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than is specifically described.

What is claimcd as new and desired to be secured by Letters Patent of the United States is:

1. For a rocket vehicle having a motor, a motor case and a motor nozzle, an integral fin and nozzle expansion cone assembly comprising:

a fin canister having a forward portion and a rearward portion,

a plurality of fins mounted on the outside of said canister supported entirely by said canister,

an adapter element,

means for removably attaching said forward portion of said fin canister to said adapter element,

an expansion cone,

means for removably attaching said expansion cone to said adapter element,

means for removably supporting said rear portion of said canister on the rear portion of said expansion cone, and

means for removably attaching said adapter element to said motor case adjacent to said nozzle such that said expansion cone is abutting said nozzle and is in fluid communication therewith.

2. The structure of claim 1 wherein said means for attaching said adapter element to said expansion cone comprises a threaded fitting.

3. The structure of claim 1 wherein said means for supporting said rear portion of said canister comprises:

a flange of outside shape and size substantially equal to the inside shape and size of said canister and attached to said expansion cone, and

locking means installed in the periphery of said canister and acting on said flange whereby said expansion cone is locked against movement.

4. The structure of claim 1 further including:

seal means interposed between said nozzle and expansion cone whereby leakage of propulsion gases be tween said nozzle and said expansion cone is preeluded.

5. The structure of claim 4 wherein said motor case and said fin canister are of cylindrical shape and of equal outside diameter, and said adapter element and said expension cone are positioned within said canister.

6. The structure of claim 5 wherein said adapter element is a truncated cone concentrically mounted about said nozzle.

7. For a rocket vehicle having a motor, a cylindrical motor case and a propulsion nozzle, an integral fin and nozzle expansion cone assembly comprising:

a fin canister of cylindrical shape having an outside diameter equal to the outside diameter of said motor case,

a plurality of outwardly oriented fins fixedly attached to said canister,

a plurality of inwardly acting set-screws installed about the rear periphery of said canister,

an adapter element of truncated conical shape having a maximum outside diameter equal to the outside diameter of said motor case,

an inwardly oriented threaded section on the rear portion of said adapter element,

means for removably attaching said adapter element to said motor case adjacent said nozzle,

means for removably attaching said fin canister to said adapter element,

a nozzle expansion cone,

an outwardly oriented threaded section on the forward portion of said expansion cone adapted to coact with said inwardly oriented threaded section to removably attach said adapter element to said expansion cone,

a flange of diameter substantially equal to the inside References Cited UNITED STATES PATENTS 3/1957 Apotheloz et al 244-328 7/1963 Iasse 2443.29

BENJAMIN A. BORCHELT, Primary Examiner. SAMUEL FEINBERG, Examiner.

V. R. PENDEGRASS, Assistant Examiner.