The SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft is a large amphibian aircraft designed by SDY's Subsidiary Sciathan Limited as a Multi-Purpose, all-weather, all-environment aircraft, capable of acting as a firefighting aircraft, passenger or cargo hauler, maritime Search and Rescue, maritime patrol, Anti-Submarine Warfare and other roles.

The term guairdeall means petrel, as in the birds of the order Procellariiformes.


The SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft is a high-wing T-tail monoplane with two turbofan engines mounted above the fuselage on the wings' roots.

The fuselage features a high length-to-beam-ratio, which makes the aircraft easier to control in water, and a small rudder. One floats at either end of the wing allow for swimming.

Equipped with triple-redundant Fly-by-Wire Systems and digital displays, the SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft allows for easy maintenance and simple controls, as well as allowing for modern navigational systems, including GPS, an autopilot and a weather radar. The glass cockpit allows for one pilot to be able to fly the aircraft safely, but we recommend a cockpit crew of two people.

The supercritical wings have a sweep angle of 25 degrees, which allows for easier take-offs and landings.

The aircraft is powered by two Luas L-36 Mark IV Turbofan Engines, highly modern engines capable of providing a maximum thrust of 75 kilo-newtons, which were built using corrosion-resistant materials. It is a three-spool high bypass turbofan engine, optimized for fuel economy. The engines are equipped with Full Authority Digital Engine Control Units, FADEC Units for short, which provide a better fuel efficiency, protect the engines against out-of-tolerance operations and provide a number of other advantages. Combined with the titanium blisks, which integrate both the blades and the compressor disks into a single part, the efficiency of the engine is higher then that of normal compressor disks and blades attached to them by elimination of the bolts and screws holding everything together, thus eliminating drag and the number of components.

The Luas L-36 Mark IV is not exactly easy to maintain, both due to the weight of the engine of one and a half tons and due to a few components' availability, but it can be done by skilled mechanics with relatively little effort.

As an amphibian, the SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft can operate from both prepared airstrips, unprepared airstrips and from the surface of the water, making it an ideal large bush plane. To that end, the SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft usually comes equipped with larger tyres, which allow for operations from rough terrain.

The SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft can safely take off from a runway 1,800 metres in length or a stretch of water 2,300 metres long with waves up to 1.3 metres high, including safety clearances and when loaded to capacity.

Both the wings and the T-Tail, as well as the engines, can be detached for ease of maintenance and storage. All SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft feature aerial refuelling capabilities.

Guairdeall Model C - The Civilian

Model C is the most basic variant, a classical amphibian floatplane capable of either hauling cargo or passengers around the countryside. The pressurized cabin allows for up to 72 passengers and their luggage, with the seats easily removable to convert the Model C into a cargo hauler capable of carrying eight tons of freight. A combination of both is possible as well.

Crewed by two pilots and with little else, Model C is a classical amphibian, which can also act as a bush plane.

Guairdeall Model FFT - The Flying Firefighting Team

Model FFT is the firefighting-model of the SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft. Incapable of carrying passengers, but eight aluminium tanks to store water for the purpose of dropping it onto a fire. The four scoops can fill the tanks, which can hold up to 12,000 litres or 12 tons of water, in 14 seconds from any longer stretch of lake, river or the sea itself. In addition to those eight tanks, four smaller tanks with a capacity of 1.3 cubic metres can be used to transport fire-retarding chemical agents and similar substances.

The tanks can be emptied in up to 1.5 seconds over the site of a fire.

The tanks can be removed to make space for cargo, but converting the Model FFT into a passenger plane is harder. Three to four men crew the Flying Firefighter Team.

Guairdeall Model S - The Rescuer

Model S is the SAR-Variation, coming equipped with a small boat, searchlights, a surface-search radar, thermal and optical surveillance systems, the latter including night vision modes, as well as medical equipment. Aim is to assist vessels in distress, salvage crew and passengers of vessels or aircraft having gone down at sea.

Two pilots and up to six rescue personnel crew the aircraft, with seats for forty rescued people and six stretchers. Alternatively, up to 36 stretchers can be taken along, making the Model S an airmobile hospital.

The S stands for sábhálaí, which means rescuer, fitting for a Search and Rescue Aircraft.

Guairdeall Model F - The Hunter

The Model F is the only variation with a military role in mind, namely maritime patrol, surveillance, including pollution control, and Anti-Submarine Warfare. Equipped with a variety of new sensors and systems, amongst them an Air/Surface Search Radar, a Magnetic Anomaly Detector, an ESM- and an ELINT-Suite, an Artio Battlescape Network Mark IV-L and the capability to carry and to deploy sonobuoys in an internal bomb bay, as well as other weapons to fit in there, this aircraft has to be crewed by two pilots, a bomb bay master, as well as six sensor technicians and a computer technician.

The radar, a Nuach N-48 Mark III, is a pulse doppler radar employing frequency hopping and control of the side lobes in order to be harder to detect, which can be used as an AWACS-Radar to detect low-flying and surface targets at a range of 400 kilometres, while a second radar, a Nuach N-26 Mark II X-Band Pulse Doppler Radar, the same one as used on the SDY-Sciathan 18 Stuama Mark II Light Multirole Fighter, is employed as an air-search radar. Both radars employ modern onboard computers to even pierce through the shroud of stealth. The radars are housed in a radome at the underside of the aircraft near the bow, which can be accessed from above.

A Magnetic Anomaly Detector, MAD for short, mounted on a rear boom, can be used to detect minute variations in the Earth's magnetic field, for example due to a mass of ferromagnetic materials, like submarines, being below the surface. Despite assurances of the contrary, ferromagnetic materials are needed in submarine construction and while the MAD has a very limited range, it is still a very viable method of searching for a submarine.

The Model F is also equipped with an ECM- and an ESM-suite, providing capabilities in Electronic Warfare. Electronic Countermeasures allow to trick and deceive enemy sensors, allowing to actively jam enemy radars and radios. ESM, Electronic Support Measures, on the other hand, allow to detect and identify, as well as analyse and record radiated electromagnetic energy, for example by radar, for threat recognition and identification and operational planning.

All that data collected by the sensors can be shared with other aircraft, vessels, command posts and ground stations via an Artio Battlescape Network Model Mark IV-L, which also allows the Model F to act as a network node – we, however, do not recommend that.

The Model F is also equipped with chaff and flare dispensers in the floats.

The internal bomb bay can not only be used to carry sonobuoys, but also for housing depth charges, naval mines, torpedoes and missiles, mostly anti-ship missiles and other large missiles. The Model F is capable of carrying both Type 40 and Type 43 Anti-Ship Missiles. Additional pylons under the wings can also carry additional fuel tanks and weaponry.

The F stands for fiagaí, which can mean hunter, fitting for an ASW-Aircraft.


Passenger Aviation in the Free Lands, as a quicker alternative to railway travel, has a history and especially with floatplanes and amphibians. It quickly took off, quite literally, and bush aircraft, which could operate everywhere (or nearly everywhere), had the major role in that traffic. The railway system still had and has its place, but air traffic by amphibian is important as well.

It was from that standpoint, that SDY-Sciathan began with the development of a large amphibian in 2010, to replace the ageing fleets of larger bush aircraft in the Free Lands and to fill a number of other, sorely needed, civilian roles like airborne firefighting and Maritime Search and Rescue.

In the meantime, the SDF also came to the realization, that they needed to replace their old fleet of their Sneachta Naval Reconnaissance Plane and Submarine Hunters and Ulóg Transport Planes – and found the SDY-Sciathan 20 Guairdeall Multi-Purpose Amphibian Aircraft to be a fitting replacement for either aircraft.

After the first flight of Model FFT in the summer of 2016, it was quickly put to good use, as the Great Woods were ravaged by a forest fire. With other prototypes of the Guairdeall, as well as older aircraft, the fire was brought under control, but was finally put out by engineers of the SDF-Army and the Younger Militias.

In 2018, the Guairdeall was unveiled at the Olgean Arms Expo and international marketing started. In the same year, the Self-Defense Forces of Nouvelle-Dunkerque ordered several aircraft of this type, assembling them in their country.

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