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Vertical stabilizer

A vertical stabilizer or tail fin is the static part of the vertical tail of an aircraft. The term is commonly applied to the assembly of both this fixed surface and one or more movable rudders hinged to it. Their role is to provide control, stability and trim in yaw (also known as directional or weathercock stability). It is part of the aircraft empennage, specifically of its stabilizers.

The vertical stabilizer is the fixed vertical surface of the empennage

The vertical tail is typically mounted on top of the rear fuselage, with the horizontal stabilizers mounted on the side of the fuselage (a configuration termed "conventional tail"). Other configurations, such as T-tail or twin tail, are sometimes used instead.

Vertical stabilizers have occasionally been used in motor sports, with for example in Le Mans Prototype racing.

Contents

Principle

Control surfaces at the tail of a conventional aircraft

The vertical tail of an aircraft typically consists of a fixed vertical stabilizer or fin on which a movable rudder is mounted. A trim tab may similarly be mounted on the rudder. Together, their role is to enable trim in the yaw direction (compensate moments in yaw generated by any asymmetry in thrust or drag), enable the aircraft to be controlled in yaw (for example, to initiate side slip during a crosswind landing), as well as provide stability in yaw (weathercock or directional stability).

The greater its position away from the center of gravity, the more effective the vertical tail can be. Thus, shorter aircraft typically feature larger vertical tails; for example, the vertical tail of the short Airbus A318 is larger than that of its longer counterparts in the A320 family.

The effectiveness of the vertical tail depends on its efficiency and the vertical tail volume coefficient (also called volume ratio), which non-dimensionalizes its area and arm with the dimensions of the main wing:

V v = S v L tail-CG S w L w {\displaystyle V_{\text{v}}={\frac {S_{\text{v}}L_{\text{tail-CG}}}{S_{\text{w}}L_{\text{w}}}}}

(where the indices v and w stand for vertical tail and wing respectively, S stands for area, and L_w is typically the mean aerodynamic chord). Values for the vertical tail coefficient vary only mildly from aircraft one type of aircraft to another, with extreme values ranging from 0.02 (sailplane) to 0.09 (jet aircraft transport).

The tail efficiency is the ratio of the dynamic pressure at the tail to that in the freestream. The tail has its maximum capability when immersed in the free stream with an efficiency of one. When partially immersed in a wake its effectiveness is reduced because the wake has a lower dynamic pressure than the free stream. The fin height may need to be increased to restore its required effectiveness in certain flight conditions. The Panavia Tornado had a tall fin for directional stability at high angles of incidence.

Trim and control in yaw

The rudder is the directional control surface and is usually hinged to the fin or vertical stabilizer. Moving it allows the pilot to control yaw about the vertical axis, i.e., change the horizontal direction in which the nose is pointing.

Maximum rudder deflection is usually controlled by a rudder travel limiter. The largest achievable angle of a rudder at a particular flight condition is called its blowdown limit. It represents a balance between the aerodynamic forces on the rudder and the mechanical forces from the actuating mechanism.

Multi-engined aircraft, especially those with wing-mounted engines, have large powerful rudders. They are required to provide sufficient control after an engine failure on take-off at maximum weight and cross wind limit and cross-wind capability on normal take-off and landing.

For taxiing and during the beginning of the take-off, aircraft are steered by a combination of rudder input as well as turning the nosewheel or tailwheel. At slow speeds the nosewheel or tailwheel has the most control authority, but as the speed increases the aerodynamic effects of the rudder increases, thereby making the rudder more and more important for yaw control. In some aircraft (mainly small aircraft) both of these mechanisms are controlled by the rudder pedals so there is no difference to the pilot. In other aircraft there is a special tiller controlling the wheel steering and the pedals control the rudder, and a limited amount of wheel steering (usually 5 degrees of nosewheel steering). For these aircraft the pilots stop using the tiller after lining up with the runway prior to take-off, and begin using it after landing before turning off the runway, to prevent over correcting with the sensitive tiller at high speeds. The pedals may also be used for small corrections while taxiing in a straight line, or leading in or out of a turn, before applying the tiller, to keep the turn smooth.[citation needed]

With the controls in the neutral position, a plane may still gently yaw to one side. This is corrected through the setting of a trim surface, often a separate trim tab mounted on the rudder but sometimes the rudder itself, to counteract the yaw and ensure the plane flies in a straight line.[citation needed]

Changing the setting of a trim tab adjusts the neutral or resting position of a control surface (such as an elevator or rudder). As the desired position of a control surface changes (corresponding mainly to different speeds), an adjustable trim tab will allow the operator to reduce the manual force required to maintain that position—to zero, if used correctly. Thus the trim tab acts as a servo tab. Because the center of pressure of the trim tab is further away from the axis of rotation of the control surface than the center of pressure of the control surface, the movement generated by the tab can match the movement generated by the control surface. The position of the control surface on its axis will change until the torque from the control surface and the trim surface balance each other.[citation needed]

  • Movement caused by the use of rudder

  • The rudder is controlled through rudder pedals on the bottom rear of the yoke in this photo of a Boeing 727 cockpit.

  • Rudder and trim tab on a light aircraft

  • The water rudders on this Cessna 208 Caravan floatplane are the small vertical surfaces on the rear end of each float. Their setting is controlled from the cockpit.

Yaw stability

The vertical tail plays a determining role in yaw stability, providing most of the required restoring moment about the center of gravity when the aircraft slips. Yaw stability is typically quantified using the derivative of moment coefficient with respect to yaw angle.

The airflow over the vertical tail is often influenced by the fuselage, wings and engines of the aircraft, both in magnitude and direction. The main wing and the horizontal stabilizer, if they are highly swept, can contribute significantly to the yaw stability; wings swept backwards tend to increase yaw stability. Sweep in the wing and horizontal tail of a conventional airplane, however, does not affect airplane trim in yaw.

Dihedral in the main wing and horizontal tail can also have a small effect on the static yaw stability. This effect is complex and coupled with the effect of wing sweep and flow about the fuselage.

Propellers, especially when they are advancing so that their axis makes an angle to the freestream velocity, can affect the static stability of an airplane in yaw.

Coupling with roll

The vertical tail affects the behavior of the aircraft in roll, since its aerodynamic center typically lies far above the center of gravity of the aircraft. When the aircraft slips to the right, the relative wind and side force on the vertical tail translate into an anti-clockwise moment in roll.

Supersonic flight

In supersonic flight, the vertical tail becomes progressively less effective with increasing Mach number until the loss of stability may no longer be acceptable. The stability is reduced because the lift, or side force, generated by the tail reduces with speed for each degree of sideslip angle (lift-curve slope). This results from the very different pressure distribution, with shock waves and expansion waves, compared to subsonic. To achieve the required stability at the maximum operating speed of the aircraft the vertical tail may be enlarged, such as on the North American F-100 Super Sabre (the initial fin area requirement was underestimated). Extra area may be added by installing ventral fins (such as on higher-speed, later versions of the Vought F-8 Crusader), or folding-down wingtips (such as on the North American XB-70 Valkyrie). If a bigger tail is not acceptable automatic rudder deflections may be used to increase the tail side force and restore directional stability. This method was used on the Avro Arrow.

Stall of the vertical tail

The vertical tail sometimes features a fillet or dorsal fin at its forward base, which helps to increase the stall angle of the vertical surface (resulting in vortex lift), and in this way prevent a phenomenon called rudder lock or rudder reversal. Rudder lock occurs when the force on a deflected rudder (e.g. in a steady sideslip) suddenly reverses as the vertical tail stalls. This may leave the rudder stuck at full deflection with the pilot unable to recenter it. The dorsal fin was introduced in the 1940s, for example on the 1942 Douglas DC-4, predating the wing strakes of the fighter aircraft developed in the 1970s, such as the F-16.

  • A dorsal fin is visible at the base of the vertical tail of this Embraer 195

Structural considerations

The rudder and fin on a large, or fast, aircraft are each subject to a considerable force which increases with rudder deflection. An extreme case occurs with a departure from controlled flight, known as an upset, which in the context of fin and rudder is excessive sideslip. For large transport aircraft the stabilizing moment necessary for recovery comes from the fin with little requirement for rudder deflection. These aircraft do not have a requirement to withstand near-full rudder deflections in these circumstances because the structural weight required to prevent structural failure would make them commercially unviable. Loss of the complete fin and rudder assembly occurred on American Airlines Flight 587 when the pilots used full rudder deflections while following in the wake of a very large jet.

Clear air turbulence caused the failure of the complete fin and rudder assembly on a Boeing B-52 Stratofortress after which the pilots made a successful landing. B-52 bombers instrumented for gust and manoeuvre loads recorded gusts from clear air turbulence considerably more than the design limit with highest loads at 34,000 feet.

The English Electric Lightning T4 prototype fin failure was caused by inertial roll coupling while doing high-rate rolls. The fin was enlarged, strengthened and roll-rate limitations were imposed. However, the first T5 also had a fin failure while doing rapid rolling trials with rocket pack extended.

A Lightning lost its fin due to interaction between aircraft in close proximity at low level when flying in formation at M 0.97 , an aerobatic display routine. Limitations were imposed including separation between aircraft when in formation.

Fin buffeting is a critical issue for fighter aircraft with twin or single fins because the fatigue life of the fin structure is reduced by the fluctuating loads caused by burst vortices impinging on the fin. The single fin on the Eurofighter Typhoon experiences buffet loads caused by burst vortices which originate from the canard and wing leading edges at high angles of attack. The sides of the top-mounted airbrake, when deflected, also shed vortices which impinge, after bursting, on the fin. Buffeting from the extended airbrake is highest when the airbrake effective angle of attack is greatest, which for a fully-extended airbrake is greatest at low aircraft angle of attack and least when manoeuvring. The McDonnell Douglas F/A-18 Hornet twin fins are subject to buffeting from the breakdown or bursting of the LEX vortex in front of the tail. The addition of a LEX fence significantly reduces the buffeting and increases fin fatigue life.

  • B-52H (AF Ser. No. 61-0023), instrumented to measure gust loads to investigate structural failures, still flying after its vertical stabilizer was lost in severe turbulence on 10 January 1964. The aircraft landed safely.

  • F/A-18C showing LEX fence which reduces fin buffeting

  • Typhoon showing extended airbrake which causes significant fin buffet

All-moving tail fin

Aircraft with all-moving fins, but which did not enter service, were the North American F-107 and the BAC TSR-2

The Lockheed SR-71 Blackbird and North American X-15 used fixed stubs for the fins and rudders for the remaining height. Conventional rudders would have been inadequate for the SR-71 because excessive deflections would have been required for the engine-out case causing unacceptable trim drag. Early configurations put forward for the X-15 show a conventional fixed fin and trailing rudder, and a ventral fin. This was changed to dorsal and ventral fins each with the outer half acting as a rudder.

Multiple tail fins

Main articles: twin tail and V-tail

Twin tail aircraft have two vertical stabilizers. Many modern combat aircraft use this configuration. The twin rudders may be used in the gear-down configuration for additional longitudinal control with toe-in or flare-out (McDonnell Douglas F/A-18 Hornet). Twin rudders are also used as an airbrake as in the case of the Lockheed Martin F-22 Raptor which uses differential rudder, together with other control surface deflections, for speed control as it has no dedicated airbrake.

A twin tail may be either H-tail, twin fin/rudder construction attached to a single fuselage, such as North American B-25 Mitchell medium bomber or Avro Lancaster, or twin-boom where the rear airframe consists of two separate boom structures each with one single fin and rudder joined by a horizontal stabiliser, such as North American Rockwell OV-10 Bronco or Armstrong Whitworth AW.660 Argosy transport

A variation on the twin tail, the triple tail has three vertical stabilizers. The WW II era Avro Manchester was given a third fin when the original twin fin proved insufficient. The Lockheed Constellation used three fins to give the airplane the required vertical stabilizer area while at the same time keeping the overall height low enough so that it could fit into hangars for maintenance.

A V-tail has no distinct vertical or horizontal stabilizers. Rather, they are merged into control surfaces known as ruddervators which control both pitch and yaw. The arrangement looks like the letter V, and is also known as a "butterfly tail". The Beechcraft Bonanza Model 35 uses this configuration, as does the Lockheed F-117 Nighthawk, Northrop YF-23.

Winglets on the canard pusher configuration Rutan VariEze and Rutan Long-EZ, acting as both a wingtip device and a vertical stabilizer. Several other derivatives of these and other similar aircraft use this design element.

Pivoting tail

An unusual cruciform design is used on the Lockheed Jetstar. For longitudinal trim the entire tail assembly pivots up and down through 10 degrees about an attachment point at the bottom of the fin rear spar.

  • Lockheed Jetstar. Evidence of its pivoting fin can be seen in the diagonal line below the horizontal stabilizer

Folding for storage

The top part of the vertical fin on the North American A-5 Vigilante folds to the side due to the hangar deck height restriction.

Devices similar to vertical tails have been used on cars such as the 1955 Jaguar D-type or the 2013 Lamborghini Veneno. On race cars, its primary purpose is to reduce sudden high-speed yaw-induced blow-overs that would cause cars to flip due to lift when subject to extreme yaw angles during cornering or in a spin.[citation needed] Since 2011, the vertical stabilizer has become mandatory for all newly-homologated Le Mans Prototypes.

Some Formula 1 teams utilized a vertical stabilizer as a way to disrupt the airflow to the rear wing reducing drag, the most radical system being the "F-duct" found in the 2010 McLaren MP4-25 and Ferrari F10. On demand by the driver, this system diverted air from a duct in the front of the car through a tunnel in the vertical fin onto the rear wing to stall it and reduce drag on the straights on which downforce was not needed.[citation needed] The system was banned for the 2011 Formula 1 season.[citation needed]

  • Ferrari F10 with vertical fin between air inlet and wing

  1. Barnard, R.H.; Philpott, D.R. (2010). Aircraft Flight (4th ed.). Harlow, England: Prentice Hall. ISBN 9780273730989.
  2. Kumar, Bharat (2005). An Illustrated Dictionary of Aviation. New York: McGraw Hill. p. 272. ISBN 0-07-139606-3.
  3. H.H.Hurt Jr (1959) Aerodynamics for Naval Aviators, p.285, Chapter 4 - STABILITY AND CONTROL, Directional Stability
  4. Jenkinson, Llyod R.; Simpkin, Paul; Rhodes, Darren (1999). Civil Jet Aircraft Design. Reston, Virginia: AIAA education series. ISBN 156347350X.
  5. Raymer, Daniel P. (1999). Aircraft Design: A Conceptual Approach (3rd ed.). Reston, Virginia: American Institute of Aeronautics and Astronautics. ISBN 1563472813.
  6. Phillips, Warren F. (2010). Mechanics of Flight (2nd ed.). Hoboken, New Jersey: Wiley & Sons. ISBN 9780470539750.
  7. Fin Design For Combat Aircraft Fundamentals Of Design - V,Air International magazine,January 1980,p.22
  8. NTSB Aircraft Accident Report PB2001-910401,NTSB/AAR-01/01,DCA91MA023,p.16 note11
  9. NTSB Aircraft Accident Report PB2001-910401,NTSB/AAR-01/01,DCA91MA023,p.14
  10. Use Of Rudder On Transport Category Airplanes,Flight Operations Technical Bulletin,Boeing Commercial Airplane Group, May 13, 2002,p.1
  11. Design For Air Combat, Ray Whitford 1987,ISBN 0 7106 0426 2, Fig.204
  12. Aerodynamics For Naval Aviators,H.H.Hurt Jr.,Revised January 1965,NAVWEPS 00-80T-80,Issued By The Office Of The Chief Of Naval Operations Aviation Training Division,p.287
  13. Fundamentals Of Design-V Fin Design For Combat Aircraft,B R A Burns,Air International magazine,January 1980,p.23
  14. "NASA Flight Education website"(PDF). Archived from the original(PDF) on February 27, 2009.
  15. Bjorn Fehrm (March 1, 2019). "Bjorn's Corner: Yaw stability, Part 2". Leeham News.
  16. Use Of Rudder On Transport Category Airplanes,A310/A300-600 FCOM Bulletin,March2002,p.2
  17. National Transportation Safety Board (26 October 2004). "In-Flight Separation of Vertical Stabilizer American Airlines Flight 587 Airbus Industrie A300-605R, N14053, Belle Harbor, New York, November 12, 2001"(PDF). Archived(PDF) from the original on 30 April 2017. Retrieved5 October 2021.
  18. Flight International magazine,13 May 1965,p.734
  19. Lightning From The Cockpit,Peter Caygill 2004,ISBN 1 84415 082 8,p.98
  20. "Journal of Aircraft September-October 2008: Vol 45 Iss 5". American Institute of Aeronautics and Astronautics. September 1, 2008 – via Internet Archive.
  21. https://www.researchgate.net/publication/268365818_Realistic_Simulations_of_Delta_Wing_Aerodynamics_Using_Novel_CFD_Methods, Figure 3 shows Hornet vortex breakdown
  22. AGARD CP 494,Vortex Flow Aerodynamics,ISBN 92 835 0623 5,p.12-2
  23. Tinker, Frank A. "Who Will Bell the Invisible CAT?" Popular Mechanics (Hearst Magazines); August 1969. pp. 94–97.
  24. Aircraft Design A Conceptual Approach,Daniel P.Raymer 1992,ISBN 0 930403 51 7,p.437
  25. Fin Design For Combat Aircraft, Fundamentals Of Design V, B R A Burns,Air International magazine, January 1980,p.22
  26. F-12 Series Aircraft Aerodynamic and Thermodynamic Design in Retrospect,Ben R. Rich,J,Aircraft,Vol. II,No.7,July 1974,p.404
  27. Hypersonic The Story of the North American X-15, Jenkins and Landis, ISBN 978 1 58007 131 4,p.35 and 188
  28. "DTIC ADA284206: Flight Testing High Lateral Asymmetries on Highly Augmented Fighter/ Attack Aircraft". 23 June 1994.
  29. Kohn, Lt. Col. Allen E. and Lt. Col. Steven M. Rainey. "F-22 Flight Test Program Update." 9 April 1999. Archived from original.
  30. JetStar II,Flight International magazine,2 July 1977,p.25,27
  31. "Aviation Week 1958-05-05". 5 May 1958.
  32. Erripis, Loannis K. (2010-12-13). "The New Audi R18 LMP1". Robotpig.net. Retrieved2011-03-30.

Vertical stabilizer
Vertical stabilizer Language Watch Edit A vertical stabilizer or tail fin 1 2 is the static part of the vertical tail of an aircraft 1 The term is commonly applied to the assembly of both this fixed surface and one or more movable rudders hinged to it Their role is to provide control stability and trim in yaw also known as directional or weathercock stability It is part of the aircraft empennage specifically of its stabilizers The vertical stabilizer is the fixed vertical surface of the empennage The vertical tail 3 is typically mounted on top of the rear fuselage with the horizontal stabilizers mounted on the side of the fuselage a configuration termed conventional tail Other configurations such as T tail or twin tail are sometimes used instead Vertical stabilizers have occasionally been used in motor sports with for example in Le Mans Prototype racing Contents 1 Function 1 1 Principle 1 2 Trim and control in yaw 1 3 Yaw stability 1 4 Coupling with roll 1 5 Supersonic flight 1 6 Stall of the vertical tail 1 7 Structural considerations 2 Configurations 2 1 All moving tail fin 2 2 Multiple tail fins 2 3 Pivoting tail 2 4 Folding for storage 3 Automotive use 4 ReferencesFunction EditPrinciple Edit Control surfaces at the tail of a conventional aircraft The vertical tail of an aircraft typically consists of a fixed vertical stabilizer or fin on which a movable rudder is mounted A trim tab may similarly be mounted on the rudder Together their role is to enable trim in the yaw direction compensate moments in yaw generated by any asymmetry in thrust or drag enable the aircraft to be controlled in yaw for example to initiate side slip during a crosswind landing as well as provide stability in yaw weathercock or directional stability 4 The greater its position away from the center of gravity the more effective the vertical tail can be Thus shorter aircraft typically feature larger vertical tails for example the vertical tail of the short Airbus A318 is larger than that of its longer counterparts in the A320 family The effectiveness of the vertical tail depends on its efficiency and the vertical tail volume coefficient 5 also called volume ratio 6 which non dimensionalizes its area and arm with the dimensions of the main wing V v S v L tail CG S w L w displaystyle V text v frac S text v L text tail CG S text w L text w where the indices v and w stand for vertical tail and wing respectively S stands for area and L w is typically the mean aerodynamic chord Values for the vertical tail coefficient vary only mildly from aircraft one type of aircraft to another with extreme values ranging from 0 02 sailplane to 0 09 jet aircraft transport 5 The tail efficiency is the ratio of the dynamic pressure at the tail to that in the freestream The tail has its maximum capability when immersed in the free stream with an efficiency of one When partially immersed in a wake its effectiveness is reduced because the wake has a lower dynamic pressure than the free stream The fin height may need to be increased to restore its required effectiveness in certain flight conditions The Panavia Tornado had a tall fin for directional stability at high angles of incidence 7 Trim and control in yaw Edit The rudder is the directional control surface and is usually hinged to the fin or vertical stabilizer Moving it allows the pilot to control yaw about the vertical axis i e change the horizontal direction in which the nose is pointing Maximum rudder deflection is usually controlled by a rudder travel limiter The largest achievable angle of a rudder at a particular flight condition is called its blowdown limit It represents a balance between the aerodynamic forces on the rudder and the mechanical forces from the actuating mechanism 8 Multi engined aircraft especially those with wing mounted engines have large powerful rudders They are required to provide sufficient control after an engine failure on take off at maximum weight and cross wind limit 9 and cross wind capability on normal take off and landing 10 For taxiing and during the beginning of the take off aircraft are steered by a combination of rudder input as well as turning the nosewheel or tailwheel At slow speeds the nosewheel or tailwheel has the most control authority but as the speed increases the aerodynamic effects of the rudder increases thereby making the rudder more and more important for yaw control In some aircraft mainly small aircraft both of these mechanisms are controlled by the rudder pedals so there is no difference to the pilot In other aircraft there is a special tiller controlling the wheel steering and the pedals control the rudder and a limited amount of wheel steering usually 5 degrees of nosewheel steering For these aircraft the pilots stop using the tiller after lining up with the runway prior to take off and begin using it after landing before turning off the runway to prevent over correcting with the sensitive tiller at high speeds The pedals may also be used for small corrections while taxiing in a straight line or leading in or out of a turn before applying the tiller to keep the turn smooth citation needed With the controls in the neutral position a plane may still gently yaw to one side This is corrected through the setting of a trim surface often a separate trim tab mounted on the rudder but sometimes the rudder itself to counteract the yaw and ensure the plane flies in a straight line citation needed Changing the setting of a trim tab adjusts the neutral or resting position of a control surface such as an elevator or rudder As the desired position of a control surface changes corresponding mainly to different speeds an adjustable trim tab will allow the operator to reduce the manual force required to maintain that position to zero if used correctly Thus the trim tab acts as a servo tab Because the center of pressure of the trim tab is further away from the axis of rotation of the control surface than the center of pressure of the control surface the movement generated by the tab can match the movement generated by the control surface The position of the control surface on its axis will change until the torque from the control surface and the trim surface balance each other citation needed Movement caused by the use of rudder The rudder is controlled through rudder pedals on the bottom rear of the yoke in this photo of a Boeing 727 cockpit Rudder and trim tab on a light aircraft The water rudders on this Cessna 208 Caravan floatplane are the small vertical surfaces on the rear end of each float Their setting is controlled from the cockpit Yaw stability Edit The vertical tail plays a determining role in yaw stability providing most of the required restoring moment about the center of gravity when the aircraft slips Yaw stability is typically quantified using the derivative of moment coefficient with respect to yaw angle 6 The airflow over the vertical tail is often influenced by the fuselage wings and engines of the aircraft both in magnitude and direction 6 The main wing and the horizontal stabilizer if they are highly swept can contribute significantly to the yaw stability wings swept backwards tend to increase yaw stability Sweep in the wing and horizontal tail of a conventional airplane however does not affect airplane trim in yaw 6 Dihedral in the main wing and horizontal tail can also have a small effect on the static yaw stability This effect is complex and coupled with the effect of wing sweep and flow about the fuselage 6 Propellers especially when they are advancing so that their axis makes an angle to the freestream velocity can affect the static stability of an airplane in yaw 6 Coupling with roll Edit The vertical tail affects the behavior of the aircraft in roll since its aerodynamic center typically lies far above the center of gravity of the aircraft 1 When the aircraft slips to the right the relative wind and side force on the vertical tail translate into an anti clockwise moment in roll 6 Supersonic flight Edit In supersonic flight the vertical tail becomes progressively less effective with increasing Mach number until the loss of stability may no longer be acceptable 11 The stability is reduced because the lift or side force generated by the tail reduces with speed for each degree of sideslip angle lift curve slope This results from the very different pressure distribution with shock waves and expansion waves compared to subsonic 12 To achieve the required stability at the maximum operating speed of the aircraft the vertical tail may be enlarged such as on the North American F 100 Super Sabre the initial fin area requirement was underestimated Extra area may be added by installing ventral fins such as on higher speed later versions of the Vought F 8 Crusader or folding down wingtips such as on the North American XB 70 Valkyrie If a bigger tail is not acceptable automatic rudder deflections may be used to increase the tail side force and restore directional stability This method was used on the Avro Arrow 13 Stall of the vertical tail Edit The vertical tail sometimes features a fillet or dorsal fin at its forward base which helps to increase the stall angle of the vertical surface resulting in vortex lift and in this way prevent a phenomenon called rudder lock or rudder reversal Rudder lock occurs when the force on a deflected rudder e g in a steady sideslip suddenly reverses as the vertical tail stalls This may leave the rudder stuck at full deflection with the pilot unable to recenter it 14 The dorsal fin was introduced in the 1940s for example on the 1942 Douglas DC 4 predating the wing strakes of the fighter aircraft developed in the 1970s such as the F 16 15 A dorsal fin is visible at the base of the vertical tail of this Embraer 195Structural considerations Edit The rudder and fin on a large or fast aircraft are each subject to a considerable force which increases with rudder deflection An extreme case occurs with a departure from controlled flight known as an upset which in the context of fin and rudder is excessive sideslip For large transport aircraft the stabilizing moment necessary for recovery comes from the fin with little requirement for rudder deflection These aircraft do not have a requirement to withstand near full rudder deflections in these circumstances 16 because the structural weight required to prevent structural failure would make them commercially unviable Loss of the complete fin and rudder assembly occurred on American Airlines Flight 587 when the pilots used full rudder deflections while following in the wake of a very large jet 17 Clear air turbulence caused the failure of the complete fin and rudder assembly on a Boeing B 52 Stratofortress after which the pilots made a successful landing B 52 bombers instrumented for gust and manoeuvre loads recorded gusts from clear air turbulence considerably more than the design limit with highest loads at 34 000 feet 18 The English Electric Lightning T4 prototype fin failure was caused by inertial roll coupling while doing high rate rolls The fin was enlarged strengthened and roll rate limitations were imposed However the first T5 also had a fin failure while doing rapid rolling trials with rocket pack extended 19 A Lightning lost its fin due to interaction between aircraft in close proximity at low level when flying in formation at M 0 97 an aerobatic display routine Limitations were imposed including separation between aircraft when in formation 19 Fin buffeting is a critical issue for fighter aircraft with twin or single fins because the fatigue life of the fin structure is reduced by the fluctuating loads caused by burst vortices impinging on the fin The single fin on the Eurofighter Typhoon experiences buffet loads caused by burst vortices which originate from the canard and wing leading edges at high angles of attack The sides of the top mounted airbrake when deflected also shed vortices which impinge after bursting on the fin Buffeting from the extended airbrake is highest when the airbrake effective angle of attack is greatest which for a fully extended airbrake is greatest at low aircraft angle of attack and least when manoeuvring 20 The McDonnell Douglas F A 18 Hornet twin fins are subject to buffeting from the breakdown or bursting of the LEX vortex in front of the tail 21 The addition of a LEX fence significantly reduces the buffeting and increases fin fatigue life 22 B 52H AF Ser No 61 0023 instrumented to measure gust loads to investigate structural failures still flying after its vertical stabilizer was lost in severe turbulence on 10 January 1964 The aircraft landed safely 23 F A 18C showing LEX fence which reduces fin buffeting Typhoon showing extended airbrake which causes significant fin buffetConfigurations EditAll moving tail fin Edit Aircraft with all moving fins but which did not enter service were the North American F 107 24 and the BAC TSR 2 25 The Lockheed SR 71 Blackbird and North American X 15 used fixed stubs for the fins and rudders for the remaining height Conventional rudders would have been inadequate for the SR 71 because excessive deflections would have been required for the engine out case causing unacceptable trim drag 26 Early configurations put forward for the X 15 show a conventional fixed fin and trailing rudder and a ventral fin This was changed to dorsal and ventral fins each with the outer half acting as a rudder 27 North American X 15 showing full chord rudders on fixed dorsal and ventral stabilizersMultiple tail fins Edit Main articles twin tail and V tail Twin tail aircraft have two vertical stabilizers Many modern combat aircraft use this configuration The twin rudders may be used in the gear down configuration for additional longitudinal control with toe in or flare out McDonnell Douglas F A 18 Hornet 28 Twin rudders are also used as an airbrake as in the case of the Lockheed Martin F 22 Raptor which uses differential rudder together with other control surface deflections for speed control as it has no dedicated airbrake 29 A twin tail may be either H tail twin fin rudder construction attached to a single fuselage such as North American B 25 Mitchell medium bomber or Avro Lancaster or twin boom where the rear airframe consists of two separate boom structures each with one single fin and rudder joined by a horizontal stabiliser such as North American Rockwell OV 10 Bronco or Armstrong Whitworth AW 660 Argosy transport A variation on the twin tail the triple tail has three vertical stabilizers The WW II era Avro Manchester was given a third fin when the original twin fin proved insufficient The Lockheed Constellation used three fins to give the airplane the required vertical stabilizer area while at the same time keeping the overall height low enough so that it could fit into hangars for maintenance A V tail has no distinct vertical or horizontal stabilizers Rather they are merged into control surfaces known as ruddervators which control both pitch and yaw The arrangement looks like the letter V and is also known as a butterfly tail The Beechcraft Bonanza Model 35 uses this configuration as does the Lockheed F 117 Nighthawk Northrop YF 23 Winglets on the canard pusher configuration Rutan VariEze and Rutan Long EZ acting as both a wingtip device and a vertical stabilizer Several other derivatives of these and other similar aircraft use this design element A Lockheed Constellation with a triple tail The V tail of a Belgian Air Force Fouga CM 170 Magister The Caproni Ca 3 was both twin boom and triple tail Rutan Long EZPivoting tail Edit An unusual cruciform design is used on the Lockheed Jetstar For longitudinal trim the entire tail assembly pivots up and down through 10 degrees about an attachment point at the bottom of the fin rear spar 30 31 Lockheed Jetstar Evidence of its pivoting fin can be seen in the diagonal line below the horizontal stabilizerFolding for storage Edit The top part of the vertical fin on the North American A 5 Vigilante folds to the side due to the hangar deck height restriction North American A 5 Vigilantes one with folded finAutomotive use EditDevices similar to vertical tails have been used on cars such as the 1955 Jaguar D type or the 2013 Lamborghini Veneno On race cars its primary purpose is to reduce sudden high speed yaw induced blow overs that would cause cars to flip due to lift when subject to extreme yaw angles during cornering or in a spin citation needed Since 2011 the vertical stabilizer has become mandatory for all newly homologated Le Mans Prototypes 32 Some Formula 1 teams utilized a vertical stabilizer as a way to disrupt the airflow to the rear wing reducing drag the most radical system being the F duct found in the 2010 McLaren MP4 25 and Ferrari F10 On demand by the driver this system diverted air from a duct in the front of the car through a tunnel in the vertical fin onto the rear wing to stall it and reduce drag on the straights on which downforce was not needed citation needed The system was banned for the 2011 Formula 1 season citation needed Ferrari F10 with vertical fin between air inlet and wingReferences Edit a b c Barnard R H Philpott D R 2010 Aircraft Flight 4th ed Harlow England Prentice Hall ISBN 9780273730989 Kumar Bharat 2005 An Illustrated Dictionary of Aviation New York McGraw Hill p 272 ISBN 0 07 139606 3 H H Hurt Jr 1959 Aerodynamics for Naval Aviators p 285 Chapter 4 STABILITY AND CONTROL Directional Stability Jenkinson Llyod R Simpkin Paul Rhodes Darren 1999 Civil Jet Aircraft Design Reston Virginia AIAA education series ISBN 156347350X a b Raymer Daniel P 1999 Aircraft Design A Conceptual Approach 3rd ed Reston Virginia American Institute of Aeronautics and Astronautics ISBN 1563472813 a b c d e f g Phillips Warren F 2010 Mechanics of Flight 2nd ed Hoboken New Jersey Wiley amp Sons ISBN 9780470539750 Fin Design For Combat Aircraft Fundamentals Of Design V Air International magazine January 1980 p 22 NTSB Aircraft Accident Report PB2001 910401 NTSB AAR 01 01 DCA91MA023 p 16 note11 NTSB Aircraft Accident Report PB2001 910401 NTSB AAR 01 01 DCA91MA023 p 14 Use Of Rudder On Transport Category Airplanes Flight Operations Technical Bulletin Boeing Commercial Airplane Group May 13 2002 p 1 Design For Air Combat Ray Whitford 1987 ISBN 0 7106 0426 2 Fig 204 Aerodynamics For Naval Aviators H H Hurt Jr Revised January 1965 NAVWEPS 00 80T 80 Issued By The Office Of The Chief Of Naval Operations Aviation Training Division p 287 Fundamentals Of Design V Fin Design For Combat Aircraft B R A Burns Air International magazine January 1980 p 23 NASA Flight Education website PDF Archived from the original PDF on February 27 2009 Bjorn Fehrm March 1 2019 Bjorn s Corner Yaw stability Part 2 Leeham News Use Of Rudder On Transport Category Airplanes A310 A300 600 FCOM Bulletin March2002 p 2 National Transportation Safety Board 26 October 2004 In Flight Separation of Vertical Stabilizer American Airlines Flight 587 Airbus Industrie A300 605R N14053 Belle Harbor New York November 12 2001 PDF Archived PDF from the original on 30 April 2017 Retrieved 5 October 2021 Flight International magazine 13 May 1965 p 734 a b Lightning From The Cockpit Peter Caygill 2004 ISBN 1 84415 082 8 p 98 Journal of Aircraft September October 2008 Vol 45 Iss 5 American Institute of Aeronautics and Astronautics September 1 2008 via Internet Archive https www researchgate net publication 268365818 Realistic Simulations of Delta Wing Aerodynamics Using Novel CFD Methods Figure 3 shows Hornet vortex breakdown AGARD CP 494 Vortex Flow Aerodynamics ISBN 92 835 0623 5 p 12 2 Tinker Frank A Who Will Bell the Invisible CAT Popular Mechanics Hearst Magazines August 1969 pp 94 97 Aircraft Design A Conceptual Approach Daniel P Raymer 1992 ISBN 0 930403 51 7 p 437 Fin Design For Combat Aircraft Fundamentals Of Design V B R A Burns Air International magazine January 1980 p 22 F 12 Series Aircraft Aerodynamic and Thermodynamic Design in Retrospect Ben R Rich J Aircraft Vol II No 7 July 1974 p 404 Hypersonic The Story of the North American X 15 Jenkins and Landis ISBN 978 1 58007 131 4 p 35 and 188 DTIC ADA284206 Flight Testing High Lateral Asymmetries on Highly Augmented Fighter Attack Aircraft 23 June 1994 Kohn Lt Col Allen E and Lt Col Steven M Rainey F 22 Flight Test Program Update 9 April 1999 Archived from original JetStar II Flight International magazine 2 July 1977 p 25 27 Aviation Week 1958 05 05 5 May 1958 Erripis Loannis K 2010 12 13 The New Audi R18 LMP1 Robotpig net Retrieved 2011 03 30 Retrieved from https en wikipedia org w index php title Vertical stabilizer amp oldid 1052955560, wikipedia, wiki, book,

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