Pelikan tail

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Pelikan tail design Tail pelikan.svg
Pelikan tail design

The Pelikan tail is an experimental tail design for fighter jets. It was originally conceived by Ralph Pelikan, [1] who was hired by McDonnell Aircraft, later worked for McDonnell Douglas after the merger of McDonnell with Douglas and, after another merger, retired from Boeing. The concept was used in the Northrop YF-23 fighter. However, it has been considered or included in design specifications in the McDonnell Douglas BAE Joint Strike fighter (JSF) design which was eliminated before prototype stage [2] [3]

Contents

Advantages and disadvantages

The Pelikan design differs from the typical layout of flight control surfaces and empennage (incorporating ailerons on the wing, a horizontal stabilizer with elevators and a vertical stabilizer with a rudder), in that it uses only two moveable surfaces in order to achieve control of pitch, yaw and roll. When evaluated by Boeing engineers in October 1998 while designing what became the X-32, they found advantages of greater pitch control at high angles of attack and that two tail surfaces would have a lower radar signature than the four surfaces eventually adopted. [1] [2] However, they also found that using two larger control surfaces instead of four might actually make the aircraft heavier. The bigger hydraulic pumps and cylinders needed to operate the larger surfaces would add 800 to 900 pounds (360 to 410 kg) of weight to the design. [1] This and other factors made them use a four-surface tail instead. [1]

Tests by Virginia Tech students

Virginia Tech students built a model aircraft with a Pelikan tail and got positive results for its viability using a wind tunnel. [4] The analysis by the students found several advantages such as a lower vertical surface area, which aids in stealth; less drag due to skin friction; and a lower weight due to the need for two as opposed to the usual four hydraulic actuators.[ failed verification ] [5]

See also

Related Research Articles

Tailplane

A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplanes. Not all fixed-wing aircraft have tailplanes. Canards, tailless and flying wing aircraft have no separate tailplane, while in V-tail aircraft the vertical stabiliser, rudder, and the tail-plane and elevator are combined to form two diagonal surfaces in a V layout.

T-tail

A T-tail is an empennage configuration in which the tailplane is mounted to the top of the fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs from the standard configuration in which the tailplane is mounted to the fuselage at the base of the fin.

V-tail Type of aircraft tail

The V-tail or Vee-tail of an aircraft is an unconventional arrangement of the tail control surfaces that replaces the traditional fin and horizontal surfaces with two surfaces set in a V-shaped configuration. It is not widely used in aircraft design. The aft edge of each twin surface is a hinged control surface called a ruddervator, which combines the functions of both a rudder and elevator.

Stealth aircraft Aircraft which use stealth technology to avoid detection

Stealth aircraft are designed to avoid detection using a variety of technologies that reduce reflection/emission of radar, infrared, visible light, radio frequency (RF) spectrum, and audio, collectively known as stealth technology. The F-117 Nighthawk was the first operational aircraft specifically designed around stealth technology. Other examples of stealth aircraft include the B-2 Spirit, the F-22 Raptor, the F-35 Lightning II, the Chengdu J-20, and the Sukhoi Su-57.

Northrop YF-17 Prototype fighter aircraft for the US military

The Northrop YF-17 is a prototype lightweight fighter aircraft designed by Northrop aviation for the United States Air Force's Lightweight Fighter (LWF) technology evaluation program. The LWF was initiated because many in the fighter community believed that aircraft like the F-15 Eagle were too large and expensive for many combat roles. The YF-17 was the culmination of a long line of Northrop designs, beginning with the N-102 Fang in 1956, continuing through the F-5 family.

Northrop YF-23 Prototype fighter aircraft for the US Air Force Advanced Tactical Fighter program

The Northrop/McDonnell Douglas YF-23 is an American single-seat, twin-engine stealth fighter aircraft technology demonstrator designed for the United States Air Force (USAF). The design was a finalist in the USAF's Advanced Tactical Fighter (ATF) competition, battling the Lockheed YF-22 for a production contract. Two YF-23 prototypes were built, nicknamed "Black Widow II" and "Gray Ghost".

Boeing X-32 Multirole combat aircraft prototype by Boeing

The Boeing X-32 is a concept demonstrator aircraft that was designed for the Joint Strike Fighter competition. It lost to the Lockheed Martin X-35 demonstrator, which was further developed into the Lockheed Martin F-35 Lightning II.

Lockheed YF-22 Prototype fighter aircraft for the US Air Force Advanced Tactical Fighter program

The Lockheed/Boeing/General Dynamics YF-22 is an American single-seat, twin-engine fighter aircraft technology demonstrator designed for the United States Air Force (USAF). The design was a finalist in the USAF's Advanced Tactical Fighter competition, and two prototypes were built for the demonstration/validation phase of the competition. The YF-22 won the contest against the Northrop YF-23, and entered production as the Lockheed Martin F-22 Raptor. The YF-22 has a similar aerodynamic layout and configuration as the F-22, but with differences in the position and design of the cockpit, tail fins and wings, and in internal structural layout.

Elevator (aeronautics) Aircraft flight control surface

Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, and are sometimes located at the front of the aircraft or integrated into a rear "all-moving tailplane", also called a slab elevator or stabilator.

Stabilator

A stabilator, more frequently all-moving tail or all-flying tail, is a fully movable aircraft stabilizer. It serves the usual functions of longitudinal stability, control and stick force requirements otherwise performed by the separate parts of a conventional horizontal stabilizer and elevator. Apart from a higher efficiency at high Mach number, it is a useful device for changing the aircraft balance within wide limits, and for mastering the stick forces.

Boeing Bird of Prey

The Boeing Bird of Prey was a black project aircraft, intended to demonstrate stealth technology. It was developed by McDonnell Douglas and Boeing in the 1990s. The company provided $67 million of funding for the project; it was a low-cost program compared to many other programs of similar scale. It developed technology and materials which would later be used on Boeing's X-45 unmanned combat air vehicle. As an internal project, this aircraft was not given an X-plane designation. There are no public plans to make this a production aircraft. It is characterized as a technology demonstrator.

Empennage Tail section of an aircraft containing stabilizers

The empennage, also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow. The term derives from the French language verb empenner which means "to feather an arrow". Most aircraft feature an empennage incorporating vertical and horizontal stabilising surfaces which stabilise the flight dynamics of yaw and pitch, as well as housing control surfaces.

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. It is part of the aircraft empennage, specifically of its stabilizers.

Twin tail

A twin tail is a specific type of vertical stabilizer arrangement found on the empennage of some aircraft. Two vertical stabilizers—often smaller on their own than a single conventional tail would be—are mounted at the outside of the aircraft's horizontal stabilizer. This arrangement is also known as an H-tail, as it resembles a capital "H" when viewed from rear - these were used on a wide variety of World War II multi-engine designs that saw mass production, especially on the American B-24 Liberator and B-25 Mitchell bombers, the British Avro Lancaster and Handley-Page Halifax heavy bombers, and on the Soviet Union's Petlyakov Pe-2 attack bomber.

Stabilizer (aeronautics) Aircraft component

An aircraft stabilizer is an aerodynamic surface, typically including one or more movable control surfaces, that provides longitudinal (pitch) and/or directional (yaw) stability and control. A stabilizer can feature a fixed or adjustable structure on which any movable control surfaces are hinged, or it can itself be a fully movable surface such as a stabilator. Depending on the context, "stabilizer" may sometimes describe only the front part of the overall surface.

Joint Strike Fighter program Aircraft development and acquisition program that led to the F-35

Joint Strike Fighter (JSF) is a development and acquisition program intended to replace a wide range of existing fighter, strike, and ground attack aircraft for the United States, the United Kingdom, Italy, Canada, Australia, the Netherlands, Denmark, Norway, and formerly Turkey. After a competition between the Boeing X-32 and the Lockheed Martin X-35, a final design was chosen based on the X-35. This is the F-35 Lightning II, which will replace various tactical aircraft, including the US F-16, A-10, F/A-18A-D, AV-8B and British Harrier GR7, GR9s, EA-6B and Tornado GR4. The projected average annual cost of this program is $12.5 billion with an estimated program life-cycle cost of $1.1 trillion.

Tailless aircraft

A tailless aircraft has no tail assembly and no other horizontal surface besides its main wing. The aerodynamic control and stabilisation functions in both pitch and roll are incorporated into the main wing. A tailless type may still have a conventional vertical fin and rudder.

Northrop XFT

The Northrop XFT was an American prototype fighter aircraft of the 1930s. A single engined low-winged monoplane, it was designed and built to meet a United States Navy order for an advanced carrier based fighter. It exhibited poor handling, and was rejected by the Navy, the single prototype being lost in a crash. A variant, the Northrop 3A, also was unsuccessful.

Several aviation incidents and accidents have occurred in which the control surfaces of the aircraft became disabled, often due to failure of hydraulic systems or the flight control system. Other incidents have occurred where controls were not functioning correctly prior to take-off, either due to maintenance or pilot error, and controls can become inoperative from extreme weather conditions. Aircraft are not designed to be flown in such circumstances; however, a small number of pilots have had some success in flying and landing aircraft with disabled controls.

The Tupolev Tu-404 was a wide-body superjumbo blended wing jet airliner proposed by Russian aerospace company Tupolev.

References

  1. 1 2 3 4 Evan Hadingham (2003-01-01). "Winner Take All (All the nail biting, second guessing, and sheer engineering brilliance in the battle to build the better Joint Strike Fighter.)". Air & Space Magazine: 2&3. Retrieved 2008-05-05.
  2. 1 2 "Nova Transcript: Battle of the X-Planes". PBS. 2003-02-02. Retrieved 2008-05-21.
  3. "McDD/Northrop/BAe ASTOVL/MRF/JAST/JSF studies". Secret Projects Forum. Retrieved 2021-07-19.
  4. Paper on the 42nd AIAA Aerospace Sciences Meeting and Exhibit explaining the construction of a Pelikan tail model Archived 2006-10-14 at the Wayback Machine
  5. Virginia Tech on building An Unmanned Combat Air Vehicle for the Navy Archived 2013-03-17 at the Wayback Machine (explains technical details of the Pelikan tail)