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The Oakoms Aerospace O.141 is a narrow-bodied jet airliner, capable of taking off and landing vertically or from very short runways, developed and manufactured by Oakoms Aerospace. Formally announced in the early 1990s, it is widely regarded the region's first major attempt at a VTOL airliner, despite a mixed reception from the international aviation industry.

In 1988 the Alteran Aviation Board (AAB) issued a design study "Outline Requirement" (OR) for a 100-seat VTOL airliner capable of a minimum range of 450 miles (725 km), to take of from the planned inter-city airports. Emphasis was to be on noise reduction by using steep approach and departure profiles, much like those used today at contemporary city airports. It was thought at the time that money would be better invested on designing new aircraft types than building additional airports outside of urban areas.

Oakoms Aerospace investigated various configurations of aircraft, powerplant and control systems including an early proposal using ogival delta wings and twin fins, before submitting their draft design proposal to the AAB in January 1990. The first models and designs of the planned aircraft were unveiled at the 1990 Ludlum Air Show, where it was announced the aircraft would be known as the O.141.

Following the success of the initial O.141, the design was stretched into a number of variants; including the O.141A and the O.141B. The aircraft has been mainly adopted by a few airlines to run routes that involved flying to or from runways operating inside cities.

Design

The O.141 design was a jet airliner of all-metal construction with a T-tail and a low-mounted swept wing with a quarter-chord sweepback of 28 degrees. The design featured two wing-mounted "cruise" engines and either 16 or 20 lift fan engines mounted in sponsons either side of the fuselage (eight per side).

The engines under main consideration were the Oakoms Aerospace Engines OAE.220 turbofan for forward propulsion and the Oakoms Aerospace Engines OAE.202, a high bypass ratio lift fan engine using technology developed for the Oakoms Aerospace Engines OAE.162 lift jet. Both engines were themselves design studies by Oakoms Aerospace and it was feared that there would be delays in their development due to the company's problems at the time.

Although the aircraft is usually shipped with Alteran engines, Oakoms usually allow for the installing of other forward-propulsion engines on an order-to-order basis. Variations using fewer lift fan engines for STOL operations only were also studied as it was realised that the engines could account for 15% of the total weight of the aircraft and 35% of the final cost.

During the design stage many solutions involving high-lift devices were explored including flaps blown by the "cruise" engines. The flight control system proved the greatest challenge to the design team, systems had to be devised to control the aircraft in slow or hovering flight. This was to be achieved by swivelling the lift engines in their mounts combined with varying the thrust of each engine to provide control in pitch, roll and yaw.

The lift engines were said to be a useful safety feature in the event of failure of the main 'cruise' engines, although such an event has yet to take place outside of testing scenarios. Significant design information was gained from flight trials with the Osprey fighter aircraft being developed at the same time by Alteran Aerospace.

The passenger cabin was conventional with five or six seats abreast, luggage and freight was to be loaded in pre-packed pallets and raised up into the lower fuselage using a system similar to other conventional narrow-bodied airliners.

The most unconventional and most complex aspect of the O.141 design lays within its control system. The aircraft has conventional ailerons, elevator controls and rudder that lose their efficiency with a drop in speed below the minimum value of the evolutionary speed (minimum permissible speed while maintaining controllability) in an ordinary flight, in which the lifting force is generated by the wing. For vertical and very slow forward movement, lifting fan motors are used to provide control and perform the same functions as the "exhaust pipes" used for control on the Condor Jump Jet. This requires a differentiated operation of the engines both from the point of view of thrust and the thrust vector.

For pitch control, the differentiation of thrust between the bow and stern thrusters is used, while roll control is the differentiation of thrust between the left and right engines. The yaw control requires differentiating the tilt of the engines: so the traction of some engines is deflected forward, while while the others are tilted to direct the traction backwards. As already noted, for acceleration or deceleration, all engines are deflected together backward or forward. Another consequence of the use of engines for control purposes is a very rapid response to the required thrust changes.

Variants

O.141A

Basic and most common variant of the aircraft. Has a capacity of 102–120 passengers, dependent on seat pitch. Has 16 OAE.202 lift fans installed for VTOL/STOL flight operations.

O.141A Wedgetail

Near identical to the A variant, fitted with a 'tophat' non-rotary active electronically scanned array radar antenna, capable of tracking targets up to 850 km. Has 16 OAE.202 lift fans for VTOL/STOL flight capability. Capable of extended mission times using air-to-air refuelling.

O.141B

Near identical to the A variant, though fuselage increased in length to 135 ft 2 in (41.2 m) to accommodate up to 160 passengers. Has 20 OAE.202 lift fans for VTOL/STOL flight capability.

Specifications

Operators

• Alteran Overseas Airways Corporation - Alteran Republics (Passenger)

• Confederate Airways - Alteran Republics (Passenger)

• dragonFly - Alteran Republics (Passenger)

• Magarati Airlines - Athara magarat (Passenger)

• Northeast Airlines - Dormill and Stiura (Passenger)

• ZIP! - Alteran Republics (Passenger)
  

Liveries

Dormill and Stiura's O.141A of Northeast Airlines	Alteran Republics' O.141A of ZIP! Airways
Alteran Republics' O.141B of Confederate Airways	Athara magarat's O.141A of Magarati Airlines
Athara magarat's O.141B of Magarati Airlines
Unpainted O.141A	Unpainted O.141B
Unpainted O.141A Wedgetail

Related Articles

Alteran Aerospace / Fortitude Prospect 3-11 Series
Alteran Aerospace 4-11 Series
Alteran Aerospace 8-11 Series
Caelius Dynamics C-100 Series
Caelius Dynamics C-110 Series
Oakoms Aerospace O.141
Oakoms Aerospace O.364

Welcome to GOV.ALT, the portal to all government agencies, information and services provided by the Government of Altera.

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The websites of all government departments and many other agencies and public bodies have been merged into GOV.ALT.

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The Alteran Aerospace 8-11 Series is an Alteran long-haul, mid-size widebody, twin-engine jet airliner made by Alteran Aerospace. Its variants seat 190 to 360 passengers in typical three-class seating configurations. It is the first airliner with an airframe constructed primarily of composite materials.

The 8-11 was designed to be 20% more fuel-efficient than the AAe 4-11, which it was intended to replace. The 8-11's distinguishing features include mostly electrical flight systems, raked wingtips, and noise-reducing chevrons on its engine nacelles.

The aircraft's initial designation was the L-11, prior to its renaming in Feburary 2010. The first 8-11 was unveiled in a roll-out ceremony on July 8, 2017 at AAe's Ludlum factory in Northern Altera. Development and production of the 8-11 has involved a large-scale collaboration with numerous suppliers worldwide.

Final assembly takes place at the Alteran Aerospace Ludlum Factory in Ludlum, Altera, and at the Alteran Aerospace factory in Dylekirk, Noronica. Originally planned to enter service in May 2016, the project experienced multiple delays. The airliner's maiden flight took place on May 6th 2014, and completed flight testing in mid-2016. AAe has reportedly spent in excess of $40 billion on the 8-11 program.

Inspired by the success of the 4-11, several companies lined up to take delivery of the aircraft - signing up as launch customers. These included A.O.A.C., Sterling Airways and dragonFly.

Following the success of the initial 4-11 series and its successors, the 8-11 launched with a variety of aircraft types; the 8-11 100, 200, 300 and 400. As with the 4-11, the 8-11 also accepts customized orders for additional equipment for the military and other civil aviation duties.

Design

The Alteran Aerospace 8-11 is a long-haul, widebody, twin-engine jetliner, which features light-weight construction. The aircraft is 80% composite by volume; AAe lists its materials by weight as 50% composite, 20% aluminum, 15% titanium, 10% steel, and 5% other. Aluminium has been used throughout the wing and tail leading edges, titanium is predominantly present within the elements of the engines and fasteners, while various individual components are composed of steel.

External features include a smooth nose contour, raked wingtips and engine nacelles with noise-reducing serrated edges (chevrons). The longest-range 8-11 variant can fly 8,000 to 8,500 nautical miles (9,200 to 9,800 mi; 14,800 to 15,700 km), enough to cover even the longest routes over the Western Isles. Its cruising airspeed is Mach 0.85, equivalent to 561 mph (903 km/h; 487 kn) at typical cruise altitudes. The aircraft has a design life of 44,000 flight cycles.

Among 8-11 flight systems, a key change from traditional airliners is the electrical architecture. The architecture is bleedless and replaces bleed air and hydraulic power sources with electrically powered compressors and pumps, while completely eliminating pneumatics and hydraulics from some subsystems, e.g., engine starters or brakes. AAe says that this system extracts 35% less power from the engines, allowing increased thrust and improved fuel efficiency.

The total available on-board electrical power is 1.45 megawatts, which is five times the power available on conventional pneumatic airliners; the most notable electrically powered systems include engine start, cabin pressurization, horizontal-stabilizer trim, and wheel brakes. Wing ice protection is another new system; it uses electro-thermal heater mats on the wing slats instead of traditional hot bleed air. An active gust alleviation system, similar to the system used on the B-2 bomber, improves ride quality during turbulence.

The 8-11 has a "fly-by-wire" control system similar in architecture to that of the later 4-11 designs (post-2010 built). The flight deck features multi-function LCDs, which use an industry-standard graphical user interface widget toolkit. The 8-11 flight deck includes two head-up displays (HUDs) as a standard feature. The 8-11 shares a common type rating with the larger 4-11, allowing qualified pilots to operate both models. Like other AAe airliners, the 8-11 uses a yoke instead of a side-stick.

Under consideration is future integration of forward-looking infrared into the HUD for thermal sensing, allowing pilots to "see" through clouds.

The 8-11 is the first major commercial airplane to have a composite fuselage, composite wings, and use composites in most other airframe components. Each 8-11 contains approximately 77,000 pounds (35 metric tons) of carbon fiber reinforced polymer (CFRP), made with 51,000 lb (23 t) of carbon fiber. Carbon fiber composites have a higher strength-to-weight ratio than conventional aircraft materials, and help make the 8-11 a lighter aircraft. Composites are used on fuselage, wings, tail, doors, and interior.

The first carbon/epoxy primary structure was put into service on the AAe 4-11 classic horizontal tail in 1984.

Carbon fiber, unlike metal, does not visibly show cracks and fatigue, prompting concerns about the safety risks of widespread use of the material. Although fired in 2006, several AAe engineers complained to management, and later to the public: the composite fuselage was unsafe compared to conventional aluminum designs, and in a crash, was more likely to "shatter too easily and burn with toxic fumes".

In addition, a potential issue is the porous nature of composite materials: collected moisture expanding with altitude can cause delamination. AAe responded that composites have been used on wings and other passenger aircraft parts for many years without incident, and special defect detection procedures will be instituted for the 8-11 to detect any potential hidden damage.

Variants

8-11 100

The first production version of the 8-11 series. Original model first flew in 2018. The 8-11 was award its flight certificate in 2015 and production began 2018. Was considered by many airliners as their initial purchase aircraft.

Sub-Variants

• 8-11 100 F - Civilian/military spec. cargo hauler

• 8-11 100 RF - R variant outfitted for civilian/military spec. cargo hauler

• 8-11 100 'Guardian' - Military airborne early warning radar (AWACS)

• 8-11 100 'Sea Maiden' - Military airborne anti-submarine and maritime patrol

8-11 200

The 8-11 200 was a development of the original 8-11 100 aircraft.

Sub-Variants

• 8-11 200 F - Civilian/Military Spec. Cargo Hauler

• 8-11 200 T - Military aerial refuelling tanker

• 8-11 200 'Guardian' - Military Airborne Early Warning Radar (AWACS)

• 8-11 200 'Sea Maiden' - Military Airborne Anti-Submarine and Maritime Patrol

8-11 300

A direct development of the 8-11 200, the 8-11 300 saw a lengthened fuselage to accommodate a higher volume of either passengers or cargo.

Sub-Variants

• 8-11 300 F - Civilian/Military Spec. Cargo Hauler

• 8-11 300 T - Military aerial refuelling tanker

8-11 400

Being the second largest of the 8-11 series, the 8-11 400 has the second largest fuselage and most powerful engines of the 8-11 series.

Sub-Variants

• 8-11 400 F - Civilian/Military Spec. Cargo Hauler

• 8-11 400 T - Military aerial refuelling tanker

• 8-11 400 'Guardian' - Military Airborne Early Warning Radar (AWACS)

• 8-11 400 ULR - 'Ultra Long Range' variant, increasing range to 15,000 km

8-11 500

Being the largest of the 8-11 series, the 8-11 500 has the largest fuselage and most powerful engines of the 8-11 series.

Sub-Variants

• 8-11 500 F - Civilian/Military Spec. Cargo Hauler

• 8-11 500 ULR - 'Ultra Long Range' variant, increasing range to 15,000 km

Specifications

Operators

• Alteran Overseas Airways Corporation - Alteran Republics (Passenger)

• Baersk Air Services - Alteran Republics (Freight)

• Confederate - Alteran Republics (Passenger)

• dragonFly - Alteran Republics (Passenger)

• Sterling Airways - Alteran Republics (Passenger)

• Alteran Air Defence Force - Alteran Republics (Tanker / Transport)

• Blakenham Defence Force - Blakenham (Transport)

• Magarati Airlines - Athara magarat (Passenger)

• Razzgriz Air Force - Razzgriz (Transport / Tanker)
  

Liveries

Alteran Aerospace 8-11 100 launch livery	Alteran Aerospace 8-11 200 launch livery
Alteran Aerospace 8-11 300 launch livery	Alteran Aerospace 8-11 400 launch livery
Alteran Aerospace 8-11 500 launch livery	Alteran Republics's 8-11 200 T of the Alteran Air Defence Force
Alteran Republics's 8-11 200 'Guardian' of the Alteran Air Defence Force	Athara magarat's 8-11 100 of Magarati Airlines
Athara magarat's 8-11 200 of Magarati Airlines	Athara magarat's 8-11 400 of Magarati Airlines
Alteran Republics's 8-11 200 of Baersk Air Services	Alteran Republics's 8-11 200 of Confederate
Alteran Republics's 8-11 300 of Confederate	Alteran Republics's 8-11 400 of Confederate
Dormill and Stiura's 8-11 500 in Presidential Livery	Segentova's 8-11 300 in Presidential Livery
Alteran Republics's 8-11 300 of Alteran Overseas Airways Corporation (2021)

Related Articles

Alteran Aerospace / Fortitude Prospect 3-11 Series
Alteran Aerospace 4-11 Series
Alteran Aerospace 8-11 Series
Caelius Dynamics C-100 Series
Caelius Dynamics C-110 Series
Oakoms Aerospace O.141
Oakoms Aerospace O.364

Welcome to GOV.ALT, the portal to all government agencies, information and services provided by the Government of Altera.

---

The websites of all government departments and many other agencies and public bodies have been merged into GOV.ALT.

Here you can see all policies, announcements, publications, statistics and consultations.

The GOV.ALT website offers quick and easy assess to a range of services, information and departments.

Find out how government services are performing and how satisfied users are.