| Merlin | |
|---|---|
.jpg) The Merlin is a low-wing, twin turboprop lightutility aircraft withretractable gear | |
| General information | |
| Type | business aircraft |
| Manufacturer | Swearingen Fairchild Aircraft |
| Designer | Ed Swearingen John T. Jennings |
| Status | Out of production, in service |
| History | |
| Manufactured | 1965-1998 |
| First flight | 13 April 1965 |
| Developed into | Fairchild Swearingen Metroliner C-26 Metroliner |
TheSwearingen Merlin or theFairchild Aerospace Merlin is a pressurized, twinturboprop business aircraft first produced bySwearingen Aircraft, and later byFairchild at a plant inSan Antonio,Texas.
The Merlin was an evolution of earlier modification programs performed by Swearingen Aircraft.Ed Swearingen started the developments that led to the Merlin through gradual modifications to theBeechcraft Twin Bonanza andQueen Air business aircraft which he dubbedExcalibur. Then a hybrid aircraft was developed, with a new fuselage and vertical fin, mated to salvaged and modified(wet) Queen Air wings and horizontal tails, and Twin Bonanza landing gear: the Merlin.
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The prototype IIA took to the air for the first time on 13 April 1965, about fifteen months after the competingBeech Model 65-90 King Air (which was also derived from the Model 65 Queen Air). 36 Merlin IIA models were built before a follow-on model withGarrett AiResearch TPE-331-1 engines called theSA26-AT Merlin IIB entered production after AiResearch was appointed as distributor for the type.[1] The TPE-331 became the definitive engine of all subsequent production Merlins and the longer-fuselageMetros that were to follow.
These visual similarities ended with the next model, theSA226-T Merlin III, which was placed in production in February 1972 after 87 Merlin IIBs were built. This had new wings and engine nacelles with inverted inlet Garrett engines (this again becoming a defining feature of all subsequent production models), new landing gear with two wheels on each leg, a redesigned horizontal tail mounted on the vertical fin instead of on the fuselage as in earlier models (This and subsequent Merlin and Metro models have a trimmable horizontal stabilizer (THS) usually used on jet aircraft, one of only two turboprop aircraft types to have this design feature). and a redesigned longer nose with room for a baggage compartment as well as theavionics found in the noses of Merlin II series aircraft. All of these design changes came from the Metro design, which was undergoing development in the late 1960s.
TheSA226-TC Metro was more-or-less a new design, conceptually a stretch of the Merlin II (which it superficially resembled) sized to seat 22 passengers. Prototype construction of the Metro began in 1968 and first flight was on 26 August 1969. The standard engines offered were two TPE331-3UW turboprops driving three-bladed propellers. A corporate version called theSA226-AT Merlin IV was also marketed and initially sales of this version were roughly double that of the Metro.[2] These sales were not immediately forthcoming however, as the company was financially stretched by the development of the Metro prototype and lacked the funds to gear up for production.[3] This situation was rectified in late 1971 when Ed Swearingen agreed to sell 90% of the company to Fairchild; the company was then renamed Swearingen Aviation Corporation.
By the end of 1972 six Merlin IVs had been built[4] and production gradually built up alongside the concurrently produced short-fuselage Merlin III. In 1974, the original Merlin IV and Metro models were replaced by theSA226-AT Merlin IVA and theSA226-TC Metro II after about 30 Merlin IVs and about 20 Metros had been built.[5] Among the changes made were larger, ovalised rectangular windows replacing the circularporthole-style windows of the early aircraft, and optional provision for a smallRocket-Assisted Take Off (RATO) rocket in the tail cone, this being offered to improve takeoff performance out of "hot & high" airfields. The same year the Merlin III was replaced by theSA226-T Merlin IIIA, with an extra window on the right side of the cabin and a small window aft of the airstair on each side of the fuselage. Customers for the Merlin IIIA included theArgentinian Air Force, theArgentine Army and theBelgian Air Force.
In January 1979 production of the Merlin IIIA ended in favour of theSA226-T(B) Merlin IIIB. The IIIB differed mainly by TPE331-10U engines of increased power driving four-bladed propellers turning in the opposite direction to those of earlier models. TheSA227-TT Merlin IIIC was next, introduced concurrently with theSA227-AC Metro III (the first Metro III was Fairchild c/n AC-420 and the first Merlin IIIC was c/n TT-421, Metro and Merlin aircraft at this stage being numbered consecutively with different prefixes to denote the different types), and theSA227-AT Merlin IVC version of the Metro III followed shortly after (the first Merlin IVC was c/n AT-423). The Merlin IIIC was a redesign to incorporate structural and other changes but was visually the same as the Merlin IIIB, the redesign taking place to make the aircraft compliant with Special Federal Aviation Regulation 41 (SFAR-41).
The Merlin IVC version was initially certified in 1980 at up to 14,000 pounds (6,400 kg) this increasing to 14,500 pounds (6,600 kg) as engines and structures were upgraded. An option to go as high as 16,000 pounds (7,300 kg) was offered. Other improvements incorporated into the Merlin IVC were a 10 ft (3.0 m) increase in wing span (achieved by the simple expedient of removing the wingtips from the Metro II wing, bolting an extension to the end of each wing, and fitting a new wingtip, redesigned to reduce drag), TPE331-11U engines with redesigned "quick-access" engine cowlings and driving four-bladed propellers as on the Merlin IIIB, and other drag-reducing airframe modifications including landing gear doors that close after the gear is extended. The US Army bought a second-hand Merlin IVC and operated it as the solitary UC-26C.[6]
Towards the end of production of the short-fuselage variants of the Merlin, optionalwinglets were offered. Ten of the last 25 SA227-TTs were built with the winglets asMerlin 300s. Production of short-fuselage Merlins ended in 1983 with the building of Merlin IIIC c/n TT-541. The last Merlin IVC (c/n AT-695B) was built in 1987 and Metro production ended in 1998.[3]
TheSA26 Merlin is apressurized Excalibur fitted with a differentLycoming TIGO-540 6-cylinder geared piston engine. The TIGO 540 was used despite the fact that one of the reasons the IO-720 was used in the Excalibur was that the Queen Air series' IGSO-480 and IGSO-540 engines from the same manufacturer were so troublesome. The decision was soon made to offer increased engine power, which was achieved through installing twoPratt & Whitney Canada PT6A-20 turboprop engines, resulting in theSA26-T Merlin IIA.
The Merlin IIAs and IIBs were visually still obviously derivatives of the Queen Air, featuring as they did Queen Air tailplanes and wings with the same flat-top engine nacelles as the Excalibur Queen Airs; theairstair in the same place and of the same general design as the Queen Air; and the nose being especially similar, of the same general shape with access panels the same size, shape and location as those of the Queen Air.
The Australian Department of Civil Aviation (now theCivil Aviation Safety Authority) took delivery of four Merlin IIBs in 1969 and operated them for almost fifteen years.[7]
As of May 2021 there have been 63 documented incidents and 96 deaths involving the Merlin.[14] Listed below are a select few of the most notable ones.
Data fromJane's All The World's Aircraft 1982–83.[18]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
Related lists
Media related toSwearingen Merlin at Wikimedia Commons
