The Speedtwin E2E Comet 1, originally named the Phillips ST1 Speedtwin, is a two-seat, twin engined aircraft designed in the UK to be capable of

aerobatic Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aeroplane" and "acrobatics". Aerobatics are performed in aeroplanes and gl ...

s and the only civil twin certified for intentional spinning. After a long development time, just two have been built.

Design and development

Peter Phillips began work on the design of the Speedtwin aerobatic twin in 1981 and the first prototype flew for the first time on 30 September 1991. This, known as the ST1 was unlike the intended production machines, having modified

Victa Airtourer The Victa Airtourer is an all-metal light low-wing monoplane touring aircraft that was developed in Australia, and was manufactured in both Australia and New Zealand. Design and development The Airtourer was the winning design, submitted by Hen ...

wings, a welded steel tube

fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...

, a wooden vertical tail and fixed, spatted landing gear from a DHC-1 Chipmunk. It was powered by a pair of Continental O-200-A flat four engines. Seriously damaged in a taxying accident in the early 2000s, it probably did not fly again. Just before Phillips's death on 18 March 1996 a second prototype was begun, eventually making its first flight on 27 March 2007 powered by Avia M 332 inverted four cylinder in-line engines as the ST2 pre-production aircraft. It was later fitted with Titan/ Lycoming IO-390 flat four engines. Speedtwin Developments had taken over the aircraft in 2000 and in 2012 announced the new name of Comet 1. E2E stands for "Engineered to excel". At this time future developments including a retracting undercarriage, armament and turbo-prop engines were planned; the original idea of offering kits for home building had been withdrawn. The Speedtwin ST2 is a

low Low or LOW or lows, may refer to: People * Low (surname), listing people surnamed Low Places * Low, Quebec, Canada * Low, Utah, United States * Lo Wu station (MTR code LOW), Hong Kong; a rail station * Salzburg Airport (ICAO airport code: LO ...

cantilever A cantilever is a rigid structural element that extends horizontally and is unsupported at one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a cantilev ...

wing monoplane with wing mounted engines. Mounted with some dihedral, the wing is trapezoidal in plan, though there is little sweep on its

leading edge The leading edge is the part of the wing that first contacts the air;Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. alternatively it is the foremost edge of an airfoil sectio ...

. The

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...

s carry servo assisted

ailerons An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

and electrically driven plain flaps with a range of deflections between 0° and −40°. The vertical tail is straight tapered with a brief fuselage

fillet Fillet may refer to: *Annulet (architecture), part of a column capital, also called a fillet *Fillet (aircraft), a fairing smoothing the airflow at a joint between two components *Fillet (clothing), a headband *Fillet (heraldry), diminutive of the ...

; the

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw ...

extends down to the keel via a small

elevator An elevator (American English) or lift (Commonwealth English) is a machine that vertically transports people or freight between levels. They are typically powered by electric motors that drive traction cables and counterweight systems suc ...

cut-out. The horizontal tail, mounted on the upper fuselage, is also straight edged with slight sweep on its leading edge. Both rudder and elevators are aerodynamically balanced. Apart from a tubular cockpit frame and

composite Composite or compositing may refer to: Materials * Composite material, a material that is made from several different substances ** Metal matrix composite, composed of metal and other parts ** Cermet, a composite of ceramic and metallic material ...

wing tip A wing tip (or wingtip) is the part of the wing that is most distant from the fuselage of a fixed-wing aircraft. Because the wing tip shape influences the size and drag of the wingtip vortices, tip design has produced a diversity of sha ...

s, the Speedtwin ST2 is an aluminium

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

structure throughout. The fuselage is flat sided, with rounded decking into which the single piece, starboard hinged

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...

merges. The

cockpit A cockpit or flight deck is the area, on the front part of an aircraft, spacecraft, or submersible, from which a pilot controls the vehicle. The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls th ...

seats two in

tandem Tandem, or in tandem, is an arrangement in which two or more animals, machines, or people are lined up one behind another, all facing in the same direction. ''Tandem'' can also be used more generally to refer to any group of persons or objects w ...

with the pilot in front when flying solo; dual controls are fitted. There is a baggage area behind the rear seat. The Speedtwin has a fixed

conventional undercarriage Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail.Crane, Dale: ''Dictionary of Aeronautical Ter ...

, its mainwheels, fitted with

hydraulic brake A hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing glycol ethers or diethylene glycol, to transfer pressure from the controlling mechanism to the braking mechanism. History During 1904, Frederic ...

s, on oleo legs from below each engine, giving it a track. It has flown both with and without wheel and leg fairings. The tailwheel is steerable. The Speedtwin has flown at three

Farnborough Airshow The Farnborough International Airshow is a trade exhibition for the aerospace and defence industries, where civilian and military aircraft are demonstrated to potential customers and investors in Farnborough, Hampshire. Since its first show in ...

s, in 1994, 1996 and 2012.

Variants

;ST1: First prototype. Non-standard construction, Continental O-200-A engines ;ST2: Second prototype/first preproduction aircraft. Avia M 332, then Lycoming IO-390 engines.

Specifications (ST2, Lycoming engines)

References

External links

{{commons category, Phillips Speedtwin
NACA 23012 airfoilNACA 2412 airfoil
1990s British sport aircraft Low-wing aircraft Aircraft first flown in 1991 Twin piston-engined tractor aircraft