US3690561A

US3690561A - Thrust controlling system

Info

Publication number: US3690561A
Application number: US87167A
Authority: US
Inventors: Earl B Potter
Original assignee: Rohr Inc
Current assignee: Rohr Inc
Priority date: 1970-11-05
Filing date: 1970-11-05
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12

Abstract

System includes a shroud surrounding a jet engine with a tail pipe extending rearward of the aft end of the shroud. A nozzle coaxial with the tail pipe is slidably mounted to the shroud for axial movement. In first, cruising, position the forward portion of the nozzle overlaps the tail pipe and the forward end of the nozzle is adjacent to the aft end of the shroud to form a continuous streamlined body. The inner wall of the nozzle aft portion includes a forward section which conforms to the exit end of the tail pipe and converges rearward. The aft section is generally cylindrical but may be slightly convergent or divergent. The entire aft portion of the nozzle comprises front hinged petals which swing outward to increase the gas flow path area and also to form a convergent-divergent nozzle for afterburner operation. The nozzle slides rearward to second, reversing, position with its forward end adjacent to the exit plane of the tail pipe. Lateral openings are exposed when the nozzle is moved axially rearward and the blocker doors are opened to form outflow passages for exhaust gas to produce reverse thrust. Blocker doors and deflector doors form parts of the inner and outer wall at the openings and are pivoted on transverse axes. Linkage anchored to the shroud swings blocker doors inward in response to rearward movement, and linkage between blocker doors and deflector doors swings latter in response to swinging of former. When deployed, the deflector doors form continuations of the blocker doors to guide the outflow beyond the contour of the nozzle.

Description

United States Patent Potter Sept. 12, 1972 [54] THRUST CONTROLLING SYSTEM [72] Inventor: Earl B. Potter, El Cajon, Calif.

[58] Field of Search ..239/265.l9, 265.29, 265.31,

[56] References Cited UNITED STATES PATENTS 2,970,432 2/1961 Cocoros et al ..239l265.39 2,928,234 3/l960 Brown ..239/265.39 3,134,226 5/1964 Gardiner et a] ..239/265.29

Primary Examiner-Lloyd L. King Attorney-George E. Pearson [57] ABSTRACT System includes a shroud surrounding a jet engine with a tail pipe extending rearward of the aft end of the shroud. A nozzle coaxial with the tail pipe is slidably mounted to the shroud for axial movement. In first, cruising, position the forward portion of the nozzle overlaps the tail pipe and the forward end of the nozzle is adjacent to the aft end of the shroud to form a continuous streamlined body. The inner wall of the nozzle aft portion includes a forward section which conforms to the exit end of the tail pipe and converges rearward. The aft section is generally cylindrical but may be slightly convergent or divergent. The entire aft 7 portion of the nozzle comprises front hinged petals which swing outward to increase the gas flow path area and also'to form a convergent-divergent nozzle for afterburner operation. The nozzle slides rearward to second, reversing, position with its forward end adjacent to the exit plane of the tail pipe. Lateral openings are exposed when the nozzle is moved axially rearward and the blocker doors are opened to form outflow passages for exhaust gas to produce reverse thrust. Blocker doors and deflector doors form parts of the inner and outer wall at the 'openings and are pivoted on transverse axes. Linkage anchored to the shroud swings blocker doors inward in response to rearward movement, and linkage between blocker doors and deflector doors swings latter in response to swinging of former. When deployed, the deflector doors form continuations of the blocker doors to guide the outflow beyond the contour of the nozzle.

11 Claims, 6 Drawing Figures "m" we PKTENTEDSEP 12 Ian SHEEI 2 BF 3 mm mm Om INVENTOR. EARL B. POTTER ATTORNFY PATENTEDSEP 12

I972 sum

3 or 3 FIG. 5

FIG. 6

INVENTOR. EARL B. POTTER ATTORNEY THRUST CONTROLLING SYSTEM BACKGROUND OF THE INVENTION This invention lies in the field of gas turbine engines, more commonly called jet engines, which produce reaction thrust by ejecting a high velocity stream of gas from the exhaust nozzle of the gas turbine. Airplanes driven by jet engines fly and land at much higher speeds than propeller driven aircraft. Their high landing speed puts a great burden on' the wheel brakes and of course they do not have propellers which are readily reversible to produce reverse thrust. Therefore it is necessary to provide apparatus to reverse the gas stream to accomplish this result.

It is also highly desirable to be able to control effective thrust in flight. This is particularly so in the case of tactical military airplanes. They may be required to put on a burst of speed with the aid of an afterburner operation which requires a variable area flow path for maximum effectiveness. They may also be required to decelerate rapidly in combat maneuvers or limit their speed in steep dives in bombing operations. For this purpose thrust reversers are used.

Thrust reversers and variable area nozzle controls have been used together in the past to accomplish their separate functions and have performed reasonably well. However, since they represent two completely different types of modification of the nozzle they have usually involved very complicated constructions with high first cost and an undesirable amount of maintenance. The major problem has been to incorporate both features without interference between them.

SUMMARY OF THE INVENTION The present invention accomplishes the desirable results mentioned above with minimum complication. Generally stated, the system includes a shroud surrounding the engine, and this shroud may be a fuselage, nacelle, or other structural part of the airplane. The tail pipe of the engine extends rearward beyond the fixed aft edge of the shroud. A nozzle is arranged coaxially with the tail pipe and is slidably mounted to the shroud for axial movement between a first, cruising, position and a second, reversing, position. The nozzle has inner and outer walls, and a mounting ring located within the nozzle in a plane perpendicular to the axis extends around the periphery of the nozzle and divides it into forward and aft portions.

The forward portion of the nozzle is a generally annular rigid structure with a support ring forming its leading or forward edge. Openings through the inner and outer wall define outflow passages for exhaust gas in the reverse thrust operation. A blocker door is located in each opening in the contour of the inner wall and pivotally mounted on a transverse axis for swinging to a deployed position where it mates with one or more other blocker doors to block rearward flow and divert it through the outflow passages. A deflector door is also located in each opening but in the contour of the outer wall and is pivotally mountedv on a transverse axis radially outward of the mounting axis of its respective blocker door for swinging with the blocker door to a deployed position in which it forms a continuation of its blocker door to guide the exhaust outflow beyond the contour of the nozzle.

When the nozzle is in its first or cruise position and the doors and deflector doors are stowed, the forward portion of the nozzle including the doors overlaps the tail pipe and the forward end of the nozzle is adjacent to or in engagement with the aft end of the shroud. As the nozzle moves rearward to its second position, linkage between the nozzle and the doors causes them to deploy in response to, and proportionally to, such movement. Thus, the forward thrust is reduced, and the reverse thrust is increased as the second position is approached, until the maximum thrust effect is attained as the forward end of the nozzle is adjacent the exit plane of the tail pipe and the doors and deflectors are fully deployed to defect the exhaust gas flow outward and forward. The mechanism is simple and is completely divorced from the variable area features.

The aft portion of the nozzle is also modulatable to vary-the profile and flow path area to vary the amount of effective thrust for differing flight regimes such as cruising and afterburner modes. It is composed of a first plurality or set of inner petals pivotally connected at their leading edges to an inner margin of the mounting ring and arranged in peripheral adjacency around the circumference of the nozzle. They overlap in sliding relation to form an imperforate structure. These first petals are so shaped and located that when they are in stowed position for cruising and the nozzle is in its first position for cruising their leading edges are approximately in the exit plane of the tail pipe and they define the inner wall of the forward section of the nozzle aft portion and are a virtual rearward continuation of the wall of thetail pipe, converging rearward at a substantial angle.

A second plurality or set of outer petals are pivotally connected at their leading edges to an outer margin of the mounting ring and are also overlappingly and slidably arranged in peripheral adjacency around the circumference of the nozzle. These second petals are so shaped and located that in stowed position they define the outer wall of the nozzle aft portion and also the aft section of the inner wall of the nozzle aft portion in continuation of the wall defined by the first petals. They may converge or diverge slightly in stowed position but preferably form a substantially cylindrical wall.

A plurality of links connect the inner and outer petals so that they will move in unison, and an axially movable translating ring is connected by track and follower means to the inner petals to actuate them. When the ring is moved rearward, all of the petals swing out away from the axis, increasing the flow path area. The convergence of the first petals is substantially decreased and the second petals become divergent, with the result that the combined profile now defines a convergent-divergent nozzle suitable for afterburner operation.

BRIEF DESCRIPTION OF THE DRAWINGS Various advantages and features of novelty will become apparent as the description proceeds in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic longitudinal sectional view of a portion of a tail pipe and nozzle assembly embodying the invention with all of the components in stowed position;

FIG. 2 is a view similar to FIG. 1, with the com ponents in reversing position; a

FIG. 3 is a view similar to FIG. 1 with the components in afterbuming position;

FIG. 4 is a sectional view taken on line 4-4 of FIG.

FIG. 5 is a sectional view taken on line 55 of FIG. 4; and

FIG. 6 is an end elevational view looking forward at an assembly of two of the nozzles in the reversing mode.

DESCRIPTION OF PREFERRED EMBODIMENT The general arrangement schematically illustrated in FIG. 1 shows the system in its relation to other elements of a typical jet engine installation. The engine, not shown, is encased within an elongate shroud 10 having a fixed aft portion 12, and is provided with a tail pipe 14 which extends rearward of the aft end 12 of the shroud. The tail pipe has an exit end 16 of fixed diameter extending in a plane generally perpendicular to the longitudinal axis of the tail pipe and'shroud. Although the wall 18 of the tail pipe may' be entirely cylindrical it is shown .as having a slight convergence in its aft portion.

A nozzle structure 20 is provided at a locus intermediateits forward end 22 and its aft end 24 with a mounting ring 26 which generally divides it into a forward portion 28 which embodies the reversing features, and an aft portion 30 which embodies the variable area and profile features. The nozzle is coaxial with the tail pipe and is axially slidable on support tracks, not shown, carried by the shroud 10, or in some cases by sponsons. It is actuated in a conventional manner by threaded shafts 32 fixedly connected to a support ring 33 which forms the forward end of the nozzle, the shafts extending through rotating nuts 34 mounted in the shroud and rotatably driven by a flexible shaft 36. The nozzle is shown stowed in its first, or cruising position in FIG. 1. The forward portion of the nozzle is provided with a plurality of lateral openings, preferably two, through its inner and outer walls to define exhaust gas outflow passages 38. A blocker door 40 occupies most of the inner end of each passage to define a part of the inner wall of the-nozzle, and its side walls 42 which serve as fences during thrust reversal are pivoted to the nozzle at 44 on transverse axes. A deflector door 46 occupies most of the outer end of each passage to define a part of the outer wall of the nozzle, and its side walls 48 which also serve as fences during thrust reversal are pivoted to the nozzle at 50 on transverse axes. In the stowed position of FIG. 1 it will be seen that the forward portion 28 of the nozzle including the doors overlaps the tail pipe and the forward end 22 is adjacent to the aft end 12 of the shroud. Preferably it is in sealing contact.

The attitude of the doors is controlled by linkage including a link 52 pivotally connected to the nozzle at 54 and pivotally connected at 56 to a second link 58 which is pivotally connected at 60 to the blocker door side wall 42. This linkage is locked in .over center position by a stop 62. Another link 64 is pivotally connected at 66 to side wall 42 of the blocker door and at 68 to side wall 48 of the deflector door. When the nozzle is moved rearward to its second, deployed, position for reversing, as shown in FIG. 2, a roller 70 .at pivot point 56 enters cam track 72 which gradually moves the roller toward the axis. This breaks linkage 52-58 and swings the blocker doors together at the axis to block rearward flow of the exhaust gas stream and direct it out through passages 38. At the same time link 64 is pulled by the blocker door and in turn swings the deflector door to the position of FIG. 2, where it serves as a continuation of the blocker door to guide the exhaust gas stream outward of the nozzle contour. A series of peripherally adjacent petals 74 are pivoted at their leading edges to support ring 33 at 76 and are spring loaded to keep their trailing edges 78 in contact with the outer surface of wall 18 of the tail pipe throughout axial movement of the nozzle in order to seal the gap against leakage at all times. Thus it will be seen that the entire reverse thrust function is accomplished by the forward portion 28 of the nozzle and its components.

The aft portion 30 of the nozzle is shown in stowed position in FIG. 1. A first plurality or set of petals 80 is arranged in peripheral adjacency in sliding overlapping relation around the circumference of the nozzle, and each petal is pivotally connected at its leading edge 82 by pivot means 84 to a bracket 86 at the aft interior margin of mounting ring 26. The leading edges 82 are substantially in the exit plane of the tail pipe and the petals combine to define the forward section of the inner wall of the nozzle aft portion. In addition they form a virtual continuation of the wall 18 of the tail pipe as a converging nozzle section. A second plurality or set of petals 88 are arranged in peripheral adjacency around the circumference of the nozzle, and the leading edge 90 of each petal is pivotally connected at 92 to a bracket 94 at the forward outer margin of mounting ring 26. Petals 88 define the entire outer wall of the aft portion 30 and also define the aft section of the inner wall of portion 30. This aft inner wall portion 96 is generally cylindrical and its forward end 98 engages the aft end 100 of petals 80 to form a relatively smooth continuation of the flow path. Links :102, pivotally connected to petals 80 at 104 and to petals 88 at 106 cause the two sets of petals to swing in unison toward and away from the axisbetween the stowed, cruising position of FIG. 1 and the deployed, afterburning position of FIG. 3.

The mechanism for actuating the petals is illustrated in more detail in FIGS. 4 and 5. A translating ring 108 is mounted to move axially and is provided with a plurality of inwardly directed rollers 110 which engage the bases 112 of guide tracks 114. Return rollers 116 engage under the flanges 118 of the tracks. The rollers 110 resist the outward pressure of the exhaust gas stream, and in the position of FIG. 1 they hold the petals 80 in the cruising position. The links 102 serve to hold petals 88 in their cruising position. As the translating ring moves aft to the deployed position of FIG. 3, rollers 116 engaging flanges 118 of the tracks cause both sets of petals to swing outward about their pivotal mountings to the-deployed position of FIG. 3. On the return movement of the translating ring, the pressure of rollers 110 on the bases 112 of the tracks forces all of the petals back to their stowed position of FIG. 1.

The translating ring 108 is provided with a plurality of fixed ball nuts 120, see FIG. 5, which receive rotating threaded shafts 122 carried in thrust bearings 124 which are mounted on mounting ring 26. The shafts are rotated by a peripherally extending flexible drive shaft 126 through a series of drive shaft tees 128.

Returning to FIG. 3 it will be noted that the aft portion of wall 18 of the tail pipe is slightly convergent. When the petals are fully deployed for afterburning, the convergence of petals 80 is reduced to be the same as that of the tail pipe while the swinging of the outer petals 88 has caused wall 96 to assume a substantial degree of divergence. Thus the total profile now defines a convergent-divergent nozzle suited for afterburning operation. The degrees of convergence and divergence are tailored to the specific installation, but the principle of operation remains the same.

When a pairof engines are mounted in close coupled relation at the aft end of a fuselage, as shown in FIG. 6, the nozzles are rotated in opposite directions about their respective axes to a suitable degree .so that the reverser plumes will not be directed against the tail 1 control surfaces. When the engines are mounted singly as in nacelles, the nozzles are normally oriented to exhaust the plumes vertically.

Having thus described the invention, what is claimed as new and useful and is desired to be secured by US. Letters Pat. is:

1. Thrust controlling mechanism for a jet aircraft engine having a tail pipe with fixed exit area, said system comprising: a shroud of. generally annular cross sectional shape connected to and surrounding the engine; a nozzle having an inner and outer wall, said walls having a spaced relationship therebetween and substantially coaxial with the tail pipe, said nozzle having an aft portion with a forward and aft section and a forward portion partially surrounding said tail pipe, the forward portion of the inner wall having a fixed inlet area and shaped to conform to the aft end of the tail pipe, the inner wall of said forward section of said aft portion being expansively adjustable between a rearwardly convergent normal flight condition and a rearwardly expanded afterburning flight condition, said nozzle being mounted for axial fore-and-aft movement between a first, forward, flight position with the forward end of the outer wall co-extensive with the aft end of the shroud, and the forward end of the inner wall coextensive with the aft end of the tail pipe, and a second, rearward, reversing position with the forward end of the outer wall spaced aft from the shroud and the forward end of the inner wall spaced aft from the tail pipe to provide a gas outflow passage therebetween, and a pair of blocker doors mounted in opposite sides of said passage for movement between an outswung position clear of the path of gas flow through the nozzle, and an inswung position toward each other in the reversing position of the. nozzle to block rearward gas flow through the nozzle and redirect such gas flow outwardly through the passage with a forward flow component to produce a reverse thrust reaction.

2. Thrust controlling mechanism as claimed in claim 1; the aft portion of the tail pipe having a predetermined degree of convergence; and the forward section of the nozzle inner wall having, in its normal flight condition, a substantially greater degree of convergence.

3. Thrust controlling mechanism as claimed in claim 1 wherein the nozzle inner wall comprises a forward section and a co-extensive aft section disposed at a different angle to the nozzle axis from the forward section.

4. Thrust controlling mechanism as claimed in claim 3; the aft section of the nozzle inner wall being substantially cylindrical with said inner wall in its nonnal flight condition. Y t

5. Thrust controlling mechanism as claimed in claim 2; the aft section of the nozzle inner wall comprising a plurality of petals arranged in peripheral adjacency and pivotally mounted at their forward ends to swing in generally'radial paths toward and away from the axis of the nozzle to vary the exhaust gas flow area and the profile of the nozzle.

6. Thrust controlling mechanism as claimed in claim 5; the aft portion of the tail pipe having a predetermined degree of convergence; the forward section of the inner wall of the nozzle aft portion having, in its normal flight condition, a substantially greater degree of convergence, and having also, in its afterburner condition, substantially the same convergence; the aft section of the nozzle inner wall in the afterburning condition of 'the nozzle, being divergent relative to the forward section, the combined profile of the nozzle sections in the afterburning condition of the nozzle being convergent-divergent.

7. Thrust controlling mechanism as claimed in claim 2; a mounting ring located in a plane perpendicular to the axis of the nozzle at a locus intermediate the forward and aft ends of the nozzle; the nozzle inner wall forward section comprising a first plurality of petals arranged in peripheral adjacency and pivotally mounted at their forward ends to the mounting ring for swinging movement toward and away from the axis of the nozzle; the inner wall aft section comprising a second plurality of petals arranged in peripheral adjacency and pivotally mounted at their forward ends to the mounting ring and being shaped and located to form the outer wall of the nozzle from the mounting ring aft, and being swingable in generally radial planes toward and away from the axis of the nozzle; and link means interconnecting the first and second petals to cause them to swing in unison.

8. Thrust controlling mechanism as claimed in claim 7; and a translating ring located within the 'aft portion of the nozzle and movable axially toward and away from the mounting ring; guide tracks on the first plurality of petals; guide followers on the translating ring and engaging the guide tracks to swing the first petals in and out in response to axial movement of the translating ring; and actuating means extending between the mounting ring and the translating ring for axial adjustment of the latter.

9. Thrust controlling mechanism as claimed in claim 1; the blocker doors in stowed position forming substantially a forward continuation of the inner wall of the nozzle aft portion and overlying the tail pipe when the nozzle is-in its first, forward position.

10. Thrust controlling mechanism as claimed in claim 1; and a plurality of deflector doors located in opposite sides of said passage and pivotally mounted on separate transverse axes; each deflector door in stowed position being located outwardly of a blocker door, the blocker doors and deflector doors being swingable in unison to deployed position in which each deflector door forms an outward continuation of its respective blocker door to guide the diverted exhaust gas flow outwardly and with a forward component.

11. Thrust controlling mechanism as claimed in claim 10; including first linkage operatively interconnecting the shroud and the blocker doors to swing the latter in response to axial movement of the nozzle; and second linkage operatively connected between the blocker doors and the deflector doors to swing the latter in unison with the blocker doors.

Claims

1. Thrust controlling mechanism for a jet aircraft engine having a tail pipe with fixed exit area, said system comprising: a shroud of generally annular cross sectional shape connected to and surrounding the engine; a nozzle having an inner and outer wall, said walls having a spaced relationship therebetween and substantially coaxial with the tail pipe, said nozzle having an aft portion with a forward and aft section and a forward portion partially surrounding said tail pipe, the forward portion of the inner wall having a fixed inlet area and shaped to conform to the aft end of the tail pipe, the inner wall of said forward section of said aft portion being expansively adjustable between a rearwardly convergent normal flight condition and a rearwardly expanded afterburning flight condition, said nozzle being mounted for axial fore-and-aft movement between a first, forward, flight position with the forward end of the outer wall co-extensive with the aft end of the shroud, and the forward end of the inner wall co-extensive with the aft end of the tail pipe, and a second, rearward, reversing position with the forward end of the outer wall spaced aft from the shroud and the forward end of the inner wall spaced aft from the tail pipe to provide a gas outflow passage therebetween, and a pair of blocker doors mounted in opposite sides of said passage for movement between an outswung position clear of the path of gas flow through the nozzle, and an inswung position toward each other in the reversing position of the nozzle to block rearward gas flow through the nozzle and redirect such gas flow outwardly through the passage with a forward flow component to produce a reverse thrust reaction.

4. Thrust controlling mechanism as claimed in claim 3; the aft section of the nozzle inner wall being substantially cylindrical with said inner wall in its normal flight condition.

5. Thrust controlling mechanism as claimed in claim 2; the aft section of the nozzle inner wall comprising a plurality of petals arranged in peripheral adjacency and pivotally mounted at their forward ends to swing in generally radial paths toward and away from the axis of the nozzle to vary the exhaust gas flow area and the profile of the nozzle.

6. Thrust controlling mechanism as claimed in claim 5; the aft portion of the tail pipe having a predetermined degree of convergence; the forward section of the inner wall of the nozzle aft portion having, in its normal flight condition, a substantially greater degree of convergence, and having also, in its afterburner condition, substantially the same convergence; the aft section of the nozzle inner wall in the afterburning condition of the nozzle, being divergent relative to the forward section, the combined profile of the nozzle sections in the afterburning condition of the nozzle being convergent-divergent.

8. Thrust controlling mechanism as claimed in claim 7; and a translating ring located within the aft portion of the nozzle and movable axially toward and away from the mounting ring; guide tracks on the first plurality of petals; guide followers on the translating ring and engaging the guide tracks to swing the first petals in and out in response to axial movement of the translating ring; and actuating means extending between the mounting ring and the translating ring for axial adjustment of the latter.

9. Thrust controlling mechanism as claimed in claim 1; the blocker doors in stowed position forming substantially a forward continuation of the inner wall of the nozzle aft portion and overlying the tail pipe when the nozzle is in its first, forward position.