Thrust Vectoring - Technical Seminar

VISVESVARAYA TECHNOLOGICALUNIVERSITY, BELGAUM

VIII Sem B.E (ME) Seminar onTHRUST VECTORING

ByPRATAP NEERMNAVI S

USN: 1MV07ME072

Faculty SupervisorMr. A.J.K PrasadAssociate Professor

DEPARTMENT OFMECHANICAL ENGINEERINGSIRMVISVESVARAYA INSTITUTE OF TECHNOLOGY, BANGALORE

Academic year: 2013 14

THRUST VECTORING 2014

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SIRMVISVESVARAYA INSTITUTE OF TECHNOLOGY, BANGALOREDEPARTMENT OFMECHANICAL ENGINEERING

CERTIFICATEThis is to certify that Mr. Pratap Neermanvi .S , USN: 1MV07ME072 a studentof VIII Semester B.E. (Mechanical) in Department of Mechanical Engineering ofSir M Visvesvaraya Institute of Technology has successfully presented the seminaron Thrust Vectoring to fulfill the academic requirement of Seminar(10MES86).

Mr. A.J.K. Prasad Dr. D.N. DrakshayaniFaculty Supervisor H.O.D. Mechanical

Evaluators:Name Signature with Date

1. ----------------------------- -----------------------------2. ----------------------------- -----------------------------


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CONTENTSCHAPTERS1) INTRODUCTION. 41.1) TERMINOLOGIES.. 5

2) HISTORY.................. 62.1) ROCKETS................................................................ 62.2) THRUST VECTORING CONTROL IN ROCKETS.. 62.3) THE ORIGIN OF THRUST VECTORING................... 7

3) FEATURES.................. 103.1) STRUCTURAL APPROACHES 103.2) TYPE 1. 103.3) TYPE 2. 133.4) TYPE 3. 133.5) MAIN ENGINE JET EXHAUST METHOD.. 143.6) MECHANICAL THRUST VECTORING METHODS.. 143.7) VECTORING NOZZLE TYPES. 14

4) ADVANTAGES... 165) SUMMARY.................. 186) REFERENCES.... 20


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CHAPTER 1INTRODUCTION

Thrust vectoring is the ability of an aircraft or other vehicle to deflect the angle of thrustaway from the vehicles longitudinal axis. The concept of thrust vectoring is not a new one. TheGermans used graphic control vanes in the exhaust stream of their V-2 ballistic missile in ww2for directional control. Thrust vectoring in aircraft is a new practice and a concept came underwidespread consideration during the cold war.

There are several methods employed to produce thrust vectoring. Most current productionaircraft with thrust vectoring use turbofan engines with rotating nozzles or turning vanes todeflect the exhaust stream. This method can deflect thrust to as much as 90 degrees providing avertical takeoff and landing capability. However for vertical thrust the engine has to be morepowerful to overcome the weight of the aircraft, this means the aircraft requires a bigger heavierengine. As a result of the increased overall weight of the aircraft the maneuverability and agilityare reduced in normal horizontal flight.Another method to produce thrust vectoring is through fluidic thrust vector control. This isachieved using a static nozzle and a secondary flow between the primary jet and the nozzle. Thismethod is desirable for its lower weight, mechanical simplicity and lower radar cross section.

Turbofan engines Fluidic thrust vector control


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1.1 TERMINOLOGIESVTOL - Vertical Takeoff and Landing capability. The advantages of vertical takeoff and landingVTOL are quite obvious. Conventional aircraft have to operate from a small number of airportswith long runways. VTOL aircraft can take off and land vertically from much smaller areas.STOL - Short takeoff and landing. These aircraft using thrust vectoring to decrease the distanceneeded for takeoff and landing but dont have enough thrust vectoring capability to perform avertical takeoff or landing.VSTOL - An aircraft that can perform either vertical or short take off and landingsSTOVL - Short takeoff and vertical land. An aircraft that has insufficient lift for vertical flight attakeoff weight but can land vertically at landing weight.TVC - Thrust Vector Control


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CHAPTER 2HISTORY

2.1 ROCKETSThe thrust vector control history first came from rockets. The evolution of the rocket has made itan indispensable tool in the exploration of space. The ancient Chinese were the first to createrockets, but there use was confined to small fire works. Not until the 20th century did a clearunderstanding of the principles of rockets emerge, and only then did the technology of largerockets begin to evolve. Most math and physics used in spaceflight and rocket was developedin1650-1910.

The first space engineer, Konstantian Tsiolkovsky (Russian, 1857-1935). he is the first toanalyze rocket motion using. Newtons Laws of Motion and wrote numerous technical papersdescribing artificial satellites, space stations, exploration of space, etc. Tsiolkovsky stated thatthe speed and range of a rocket were limited only by the exhaust velocity of escaping gases. Forhis ideas, careful research, and great vision, Tsiolkovsky has been called the father of modernastronautics. His engineering suggestions were foresighted and technically accurate that hesuggested the use of thrust vectoring in rockets (aiming the rocket to steer the rocket) and the useof liquid fuels in the propulsions of rockets (prior to that time, only solid, dry chemical rocketshad been built).

2.2 THRUST VECTORING CONTROL IN ROCKETSAll chemical propulsion systems can be provided with one of several types of thrust vector

control (TVC) mechanisms. Some of these apply either to solid, hybrid, or to liquid propellantrocket propulsion systems, but most are specific to only one of these propulsion categories.Thrust vector control is effective only while the propulsion system is operating and creating anexhaust jet. For the flight period, when a rocket propulsion system is not firing and therefore itsTVC is inoperative, a separate mechanism needs to be provided to the flying vehicle forachieving control over its attitude or flight path. Hence, there are two types ofthrust vector control concept:(1) for an engine or a motor with a single nozzle(2) for those that have two or more nozzles


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Thrust Vectoring Control in Rockets

2.3 THE ORIGIN OF THRUST VECTORING

The vectored thrust story started in the mid 1950s when a Frenchman, Michel Wibault,proposed a single seat fighter that he called the Gyroptere. Wibault proposed to vector the thrustof four separate centrifugal blowers driven by a single 8000 HP Bristol Orion engine. He chosethe Bristol engine because it was then the most powerful turbo-shaft engine in prospect. He wasunable to interest the French authorities with this idea, but in 1956 he left a brochure with the USofficer running the Paris office of the Mutual Weapons Development Programmed ColonelChapman USAF. As Chapman was working on a engine called the Orpheus engine with BristolAero-Engines. Hence with there collaboration it led to a new Bristol engine, the Pegasus, having4 rotating nozzle. By 1959 the Pegasus 1 was running on a Bristol test-bed and Hawkerswere making the P1127 airframe.


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In October 1960 Hawkers were ready to fly the first P1127. It was decided to look at theunknowns of hovering before flying the aircraft conventionally. The engine, by now the Pegasus2 of 11,000lb thrust, was installed as shown in fig.2. The main characteristics were a largebifurcated intake and four swiveling exhaust nozzles interconnected together which enabled thethrust vector to be moved, as required, from 0 to about 18 degrees forward of the vertical. Thefigure shows the engine position in the jet.

The Pegasus 2

Although the Harrier was the first who invented thrust vectored aircraft, for three decadesYakovlev design Bureau contacted the research-development-test evaluation works connectedwith creation of thrust vectored VTOL aircraft. The experimental aircraft Yak-36 permitted toaccumulate the valuable experience in that field, and create the unique research facilities for thatnew technology in aviation in 1963. Many companies tried to solve the problems connected withthis technology, but only two of the projects were carried to completion, serial production andoperation: English "Harrier" and Russian Yak-38. In 1987, Russia has developed and tested theWorld first supersonic thrust vectored STOVL aircraft Yak-141. Whereas the first supersonicfighters in production that support thrust vectoring were Mikoyan Mig-29OVT, Sukhoi Su-35and Sukhoi Su-30MKI. The best known example of thrust vectoring in an engine is the Rolls-Royce Pegasus engine of the Hawker-Siddeley Harrier brother to the BS100. (with variants builtby McDonnell Douglas). The technique has been used in various experimental and developmentplanes, some with vectored thrust in directions other than upwards. Widespread use of thrust


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vectoring for maneuverability in a Western fighter aircraft would have to wait for the 21stcentury, and the deployment of the Lockheed Martin F-22 Raptor fifth-generation jet fighter( introduced in 2011), with its afterburning, thrust-vectoring Pratt & Whitney F119 turbofan.Shown below is a list of aircrafts with thrust vectoring capabilities of different era.

Aircraft types First flightHawker P1127 KestrelYakovlevYak-36 Dornier DO31Harrier IIF-16 Fighting FalconSukhoi Su-35F-15S/MTDYakovlev Yak-141Sukhoi Su-30Boeing V-22 OspreyRockwell-MBB X-31F-22 RaptorSukhoi Su-37McDonnell Doughlas X-36Sukhoi Su-47Chengdu J-10Mikoyan Project 1.44Boeing X-32B

196019631967197419741985198819871989198919901990199619971997199820002001


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CHAPTER 3FEATURES

3.1 Structural Approaches to Provide Thrust VectoringHistorically Thrust Vectoring has mainly been used to provide a VTOL or STOL capacity

in an aircraft. The high thrust to weight ratio of jet engines means vertical flight using thrustvectoring seems to be feasible. To date there are only two operational jet VTOL aircraft, theBritish Harrier and the Russian YAK-38. However providing a VTOL capacity oftendisadvantages maneuverability in horizontal flight, consumes large amounts of fuel and is adetriment to stealth. So recently there have been moves to use thrust vectoring in jet fighters justfor a VSTOL capability or extra maneuverability in horizontal flight. Thrust vectoring for allthese applications can be accomplished by using some of the following methods.

3.2 Type 1: Same Propulsion system for Hover and forward flightTilt Prop- This type of aircraft tilts the engine and propeller assembly away from the

horizontal to provide vectored thrust.3.2.1 Tilt Rotor

This design is similar to tilt prop, except rotors are used instead of propellers. An exampleof this type of aircraft is the V-22 Osprey used in military service for its VSTOL and mediumweight lift capability. This aircraft also uses the deflected slipstream method to create lift whenin horizontal flight.

V-22 Osprey during vertical takeoff or landing


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3.2.2 Tilt wing

Tilting the entire wing, instead of just the rotor or propeller, provides the benefit ofincreasing aerodynamic flow over the lifting and control surfaces during transition, andminimizes the lift loss due to downwash in hover. Disadvantages, however, are that an additionalmethod of control such as a tail jet or rotor is required for control in hover, and ailerons changefrom roll control in horizontal flight to yaw control in hover. Control is especially difficult inhover during gusts due to the "barn door effect" of the wings in a vertical position.

Tilt wing aircraft

3.2.3 Deflected Slipstream

The Propeller or Jet slipstream is deflected downward with the trailing flaps or a speciallydesigned bucket, this vectors the thrust downward. This configuration is only useful forproviding a medium STOL capability and in some experimental aircraft a VTOL capability.Some Military cargo planes use this design to enable shorter takeoffs on short makeshiftrunways and faster approaches for landing. The C-17 Globemaster III uses this technology toprovide a medium STOL capability.


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C-17 Globemaster on approach for landing

In the picture note the trailing edge flaps are partially obstructing the engine exhaust whichdeflects the slipstream downwards resulting in extra lift.

3.2.4 Split Flow EngineA number of VTOL propulsion concepts use a split flow engine to provide thrust

vectoring. This involves a modification to a turbofan engine which splits airflow away from thecore airflow and is used to provide a balanced thrust vectoring solution. The Harrier uses thisconcept in the Pegasus engine in which the fan air and core air are exhausted separately throughelbow nozzles. This concept is also good for thrust vectoring in horizontal flight. The problemwith this design is that the engine must placed at the cg of the aircraft, this means the middlesection of the aircraft needs to be wider to accommodate the engine. Having a wider mid sectionincreases supersonic wave drag. This means designing a supersonic aircraft with thrust vectoringusing this design is very difficult. The picture shows separate ducting of fan and core air.

Rolls Royce Pegasus engine


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3.3 Type 2: Separate power plant for HoverOne of the easiest ways to provide thrust vectoring to a conventional aircraft is to utilize a

separate engine for providing vertical lift capability. This obviously increases the weight andcomplexity of the aircraft but it is one of the easiest approaches to provide VTOL ability. Thisdesign encounters problems when the pilot wants to achieve thrust vectoring in horizontal flight,the pilot has to start the lift engines before thrust vectoring can occur.

Engine arrangement in an aircraft with separate lift engines

3.4 Type 3: Lift plus Lift/Cruise enginesA more subtle approach than the use of separate lift engines is to size the forward flight

engine for efficient cruise, and also provide separate lift engines to provide vertical thrust. Theforward flight engine is also vectored using some type of nozzle. The vertical thrust deficiency inthe forward flight engine is compensated for with the extra lift engines. This design can providethrust vectoring for maneuverability in horizontal flight instantly on demand, but the lift enginehas to be pre-started to provide VTOL capability. This design is also still very heavy andcomplex because it has two different engines. This design was used in the YAK-38 and YAK-41.

Engine arrangement in a lift plus lift/Cruise engine aircraft


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3.5 Main Engine Jet Exhaust Turning MethodsFor thrust vectoring to occur the jet exhaust has to be turned somehow. This can be

achieved using mechanical or fluidic means.

3.6 Mechanical Thrust Vectoring MethodsMechanical thrust vectoring is achieved by mechanically deflecting the exhaust flow of an

aircraft using some sort of physical object. This is usually achieved using various nozzles orvanes.

3.7 Vectoring Nozzle Types3.7.1 Flaps

Flaps deflect the engines flow in much the same way as wing flaps deflect the external airflow see figure 15a This type of system introduces a thrust loss of approximately 3-6% whenvectored to 90 degrees. The vectoring flaps can also be external to the nozzle as a part of thewing flap.

3.7.2 BucketThe bucket thrust vectoring mechanism is similar to the commonly used clamshell thrust

reverser see figure 15b. The great advantage to this concept is that all the force is transmittedthrough the hinge line of the bucket meaning actuators can be reasonably small. Anotheradvantage of this system is that the turning surface can be made very efficient. This method canbe used to create 90 degree vectoring with about 2-3% thrust loss.

3.7.3 RotatingIn this type of nozzle (figure 15c) the tailpipe is broken along slanted lines into three pieces

as shown. The three pieces are connected with circular rotating-ring bearings so that the middle(shaded) piece can be rotated about its longitudinal axis while the other parts remain un-rotated.This causes the middle and end parts of the nozzle to vector thrust downward. This vectoringnozzle has a 3-5% thrust loss when vectoring at 90 degrees.


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3.7.4 VentralThe ventral nozzle (figure 15d) is simply a hole in the bottom of the tailpipe leading to a

downward facing nozzle. The normal exhaust opening is blocked by some sort of valve. Thesevalves can be used easily on aircraft with afterburners because they can be placed upstream ofthe afterburner. These ventral nozzles can help solve the balance problem of VTOL aircraft. Theventral nozzle has a thrust loss of 3-6% when vectored to 90 degrees.

3.7.5 Elbow NozzleThis type of nozzle is used on the AV-8 Harrier. The elbow nozzle is simple and lightweight

and doesnt require much actuating force. A disadvantage of this design is the fact that the flowis always being turned through a total of 180 degrees, even in forward flight. Because the flow isalways being turned this nozzle type suffers 6-8% thrust loss at all times. All the other types ofvectoring nozzle only impose a thrust loss during vertical flight. Usually a combination of any ofthese nozzles has the best effect for a particular aircraft design.

Mechanical Vectoring Nozzles

The inherent disadvantages of mechanical systems have hampered the development of thrust-vectoring technology until recent advances in fluidics provided solutions to overcoming thedownfalls of mechanical systems.


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CHAPTER 4Advantages of Thrust Vector Control

Thrust-vectoring research to date has successfully identified and demonstrated manypotential benefits to high-performance aircraft. These include enhanced aircraft maneuverability,performance, survivability, and stealth. The full extent of these benefits, however, has yet to berealized even with new generation aircraft because current mechanical thrust-vectoringconfigurations are heavy, complex, and expensive.4.1 Agility

A requirement of modern warfare is the improvement of maneuverability and controlcapabilities which TVC provides. The agility of aircraft can be determined by such things aspitch, roll and yaw rates, acceleration and deceleration and turning ability.4.2 Short take off and Landing (STOL)

Aircraft that have small take off and landing zones are largely advantageous as it reduces thespace required for operation of the aircraft. This allows the aircraft to operate in more compactenvironments such as aircraft carriers and airports, which as a result may decrease the size ofsuch things, or allow more aircraft to occupy the same space as a non STOL capable aircraft.4.3 Fuel Consumption, Flight Range

As evident in figures five and six, an aircraft with TVC requires less thrust to achievedesired results such flight regimes as cruise, climb and decent. This has the effect it reduces thefuel consumption of the aircraft due to the lower thrust requirement, which in turn increases theaircrafts flight range.4.4 Stealth

Using the theory that thrust vectoring can supplement control surfaces, it has been shownthat thrust vectoring has the ability to provide a tailless aircraft. On these tailless aircraftvectored thrust provides engine-based flight control. The benefits of reduced dependence on a


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rear tail are reduced drag, reduced aircraft weight, and less radar cross section. These taillessdesigns are therefore stealthier than other conventional designs as evident in figure .

Trust Vector control does have its disadvantages and limitation. Implementation of TVCincreases the weight of the aircraft, due to its complexities can also inhibit the performance ofthe aircraft, increases the cost significantly and can also not meet other requirements of theaircraft such as the cost, stealth performance criteria required of the particular aircraft.


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CHAPTER 5SUMMARY

Thrust vectoring is becoming more and more prevalent in aircraft as its benefits becomemore useful and efficient and as new and improved ways of vectoring thrust become available.Thrust vectoring is most commonly known in the harrier jet for its obvious implication of theaircrafts ability for vertical takeoff and landing, however there are many other examples of thrustvector control not only in aircraft but rockets as well. However the harrier was the first and onlysuccessful aircraft with thrust vectoring used for V/STOL capabilities until modern aircraft suchas the future released F-35. The problems and difficulties of incorporating thrust vectoring inaircraft is a contributing factor as to why more aircraft in the 20th century didnt employ thrustvectoring. The harrier as an example has the Rolls Royce Pegasus engine which is a split flowstyle engine with four elbows nozzles. The engine was used as it provides the required thrust forV/STOL capabilities, however it is quite large and heavy, and the engine must be placed at thecenter of gravity of the aircraft which intern widens the aircraft and reduces achievable airspeedand agility. These inferiorities compared to other non thrust vectored aircraft would havecontributed to the slow appearance of similar features in future aircraft due to its inability toinclude maneuverability, higher speeds partnered with thrust vectoring, as well as perhaps theharrier meeting all requirements asked of it and it being sufficient for the times. Anotherexample is the C-17 Globemaster III airlifter that deflects the jet slipstream with the trailing flapswhich vectors the thrust downwards useful for shorter take off than otherwise it being absent.

Thrust vectoring is becoming more and more prevalent in new aircraft such as the in-development F-35 and F-22. Due to the advances in thrust vector control since the era of theHarrier aircraft, new aircraft can incorporate thrust vector control and still maintain and improveon such things as maneuverability and stealth attributes. The shorter takeoff range, longer flightrange, higher maneuverability that these new aircraft with thrust vectoring posses are muchvalued when compared to other and older aircraft. The ability to out maneuver an opponent,travel further, takeoff and land faster in smaller areas are all major features that new thrustvectored control aircraft posses. As thrust vector control systems become less expensive, lessheavy and complex, such as is the case with Fluidic Thrust Vectoring methods, thrust vectoring


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will become a required feature of a fighter jet at least, to still be able to compete with other thrustvectored aircraft. Of course, these improvements are not exclusive to fighter jets, but also otheraircraft as outlined earlier such as cargo aircraft such as the C-17 Globemaster. Although thrustvectoring is not a new concept, modern advancements in thrust vectoring have made it quiteconceivable that in the future a much higher percentage of aircraft will posses thrust vector, notonly military aircraft but also other aircraft such as perhaps passenger aircraft, cargo aircraft, asits benefits are not exclusive to military applications, but many more forms of aircraft. With theseveral different ways to implement thrust vectoring such as Fluidic, mechanical, split flow orseparate engines, there are suitable options for its implementation in a range of different types ofaircraft.


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REFERENCES Thrust Vectoring, Wikipedia

http://en.win.kipedia.org/wiki/ Pitching Moment, Wikipedia

http://en.win.kipedia.org/wiki/ Vectored Thrust, NASA

http://www.lerc.nasa.gov/WWW/K-12/airplane/vecthrst.html AV-8B Harrier History

http://www.globalsecurity.org/military/systems/aircraft/av-8-history.htm History of Spaceflight, 2006

http://www.courses.psu.edu/aersp/aersp055_r81/history.html Konstantin Tsiolkovsky, 2006

http://en.wikipedia.org/wiki/Konstantin_Tsiolkovsky "Rocket" Microsoft Encarta Online Encyclopedia 2006

http://encarta.msn.com/encnet/refpages/RefArtTextonly.aspx?refid=761577900&print=0

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