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Britten-Norman BN2 Islander / Defender

 

bnislander
BN-2


In 1962 the two partners, John Britten and Desmond Norman, decided to build a plane of their own. The essential factors were low cost, all-weather construction, twin engine reliability and a good payload. The design was of classic simplicity: a one-piece wing with no dihedral, Hoerner-type tips, slab-sided fuselage with seating for up to 10 passengers. The prototype was powered by two 210-hp Continental engines with a fixed tricycle undercarriage. Bench-type seats for two people eliminated the need for a central aisle and these were accessed by three doors, two port and one starboard, with the rear door being of extra width to allow ease of cargo loading. The Islander can also be operated as a freighter carrying more than a ton of cargo. Passenger baggage is stored in a large 30 cu.ft. bin behind the cabin with an access door on the port side.The first metal was cut in September 1964 and the aircraft was hand crafted on a “Dexion” jig. The prototype took to the air for its first flight of 70 minutes on 13 June 1965 with both John Britten and Desmond Norman at the controls. There were some shortcomings which an increase in wing span by 1.22 metres and more powerful Avco Lycoming 260-hp engines cured.


A choice of wings was offered, so the plane could be fitted with the standard 49-foot-span wings or extended 53-foot wings, using raked tips and auxiliary fuel tanks.
Delivery of the Islander began in August 1967, but the great number of orders from over 50 countries forced Britten-Norman to subcontract manufacture of a number of the mini-airliners to the British Hovercraft Corporation. Others were produced in Romania by IRMA - which was then trucked to Bembridge for completion. Buyers were able to choose Lycoming engines: 260 or 300 hp. A Rajay turbocharging unit increased the Islander’s twin-engine ceiling to 26,000.


Britten-Norman developed two other variants for demonstration at the 1976 Farnborough Show, the "Firefighter" and "Agricultural Islander". While both designs proved themselves technically, no orders were forthcoming and the variants were shelved.


Arrangements were made with Rornaero in Bucharest, Romania, to produce the airframes. The engines, propellers, and undercarriage are trucked across Europe to where the aircraft are assembled under UK CAA supervision then, with basic instrumentation and a pilot’s seat fitted, the aircraft is flown in dull grey primer to Bembridge to be completed to customer’s requirements.


The BN-2 Super was developed by inserting a 33-inch plug in the fuselage of the production prototype, G-ATWU, allowing for an additional row of seats, however, the version was never put into production. To increase the Islander’s hot and high performance Lycoming IO-540K 300-hp fuel-injected engines were fitted. Another modification involved fitting wingtip tanks which increased the span to 53 feet while droop flaps and droop leading edges increased performance.


The first turbine-powered Islander flew in April 1977. Designated the BN2A--41, it was powered by Lycoming LTP 101 turboprops and, although its performance was described as "sparkling", it was overpowered and the fitting of the engines required major wing modifications. The project was discontinued.


In 1980 the production BN2T Turbine Islander took off with Allison 250 B17C engines. Wing fences were fitted to improve stall recovery and the prototype headed off for hot and high in Kenya and to Finland for cold weather trials.


Pilatus introduced a beefed-up Islander, the BN2B, featuring a 300 -pound increase in landing weight, including the BN-2B-20 and BN-2B-26.


In 1979 it was decided to diversify, looking at different roles as against taking people. Those sort of roles are fisheries protection, border patrol and parachuting etc. In 1978 they looked at putting a more sophisticated airborne radar into the aircraft, entering into a joint venture with Thorn EMI, using their Skymaster radar to increase the ground warning time from three or four minutes to 20-30 minutes. The name “Defender” came at that point, referring to an Islander with four wing-mounted hardpoints. Stressed to take 750lbs on the inboard pair and 350lb outboard, the hardpoints designed to carry long range fuel tanks or military stores.


Available with 260 hp, turbo-charged 260 hp, or 300 hp engines, and optional 28 cu.ft. capacity nose extension.


Defender - For general military duties PBN developed the Defender from the basic piston-engined Islander utility aircraft and, with the introduction of the Allison 250-B17C powered Turbine Islander, a parallel turbine Defender was offered. The Defender is capable of a wide range of military roles including troop transport, SAR, forward air control, electronic warfare, logistic support, and medevac.


Operationally launched by PBN on March 6, 1987, The AEW Defender is a low-cost AEW system offered in conjunction with Thorn-EMI’s Skymaster lightweight multi-mode pulse-Doppler track-while-scan radar. Acquisition and tracking of targets is automatic, and air-to-air/air-to-ground datalinks, IFF and navigation systems may be fully inte-grated with the radar’s display and control system. The Skymaster system can also be used to detect surface vessels during maritime reconnaissance missions. A large undernose radome houses the 360’-scan antenna. With appropriate computer software modifications, the AEW Defender/Skymaster combination is being offered as a solution to the British Army’s Astor requirement for an airborne battlefield surveillance radar. The British Army has bought Defender AL Mk 1s to replace Beavers.Another Defender has been flown with a Ferranti surveillance radar installed in connection with the Army’s earlier Corps Airborne Stand-Off Radar (Castor) requirement. The AEW Defender is based on the BN-2T Turbine Defender airframe.


The Maritime Defender is designed for coastal patrol, fishery and oil rig protection, and SAR durties. The Maritime Defender has Bendix RDR-1400 search radar in the nose, and four under-wing pylons to carry weapons, survival packs or other items. Either 6600 lb maximum all up weight piston-engined or 7000 lb MAUW turbine powered, the aircraft comes with both Omega and short range sector scan radar.


The Defender was officially added to the ranks of the British Army on March 10th, 1989. Design is wholly utilitarian and is most characteristically defined by the high-mounted monoplane wings. Each wing maintains an Allison 250-B17F turboprop engine powering a three-bladed propeller. The cockpit compartment is held well forward in the squared off fuselage with slab sides and features a useful sloped nose for improved downward visibility. The undercarriage is a conventional tricycle arrangement and made up of two double-tired main landing gear legs and a single-tired nose landing gear leg - as a whole, the undercarriage is non-retractable. The empennage is dominated by a single large-area vertical tail fin clipped at the top and sporting some sweep along the leading edge. Horizontal tailplanes are affixed to the vertical fin tail. Typical accommodations are for two pilots and up to six passengers. Entry/exit is via side doors, two forward and two aft. Her gross weight is listed at 7,000lbs. Each wing can field four hardpoints for various munition options to include gun pods, rocket pods and bombs if need be or external fuel tanks for extended loitering times and operational range. Specialized reconnaissance and surveillance mounts are fitted with applicable tailored equipment, cameras and jamming pods as well as communications options. Airborne Early Warning (AEW) Defenders sport a hideous-looking nose radome that quickly identifies the type and its role.


In 2003, the UK military purchased three (some sources state four) Defenders to help with the deteriorating conditions in Iraq following the 2003 coalition invasion. These aircraft carried the designation of Defender 4S AL Mk 1 and sported underwing dispensers to protect against surface-to-air guided munitions. This model was furthered defined by the implementation of an electro-optical turret under the extreme end of the nose.


The Defender 4000 is a military version of the Defender series and first flight of this system was achieved in August of 1994. The Defender 4000 features a larger wing component similar to that of the Trislander and operates with increased weight tolerances. Her engines are more powerful than previous versions and has an enlarged nose section for the fitting of search radar. Top speed is a reported 225 miles per hour.


By 1990, over 1,100 Islanders have been built with Lycoming piston engines or, in the BN-2T Turbine Islander, two 400 shp (298 kW) Allison 250-B17C turboprops.


In 1970, Britten-Norman introduced an enlarged version of the twin-engine Islander with a third engine mounted high on the tail in a tractor position. The three engines were 260-hp 0-540-E4C flat-sixes turning Hartzell two-blade constant-speed fully feathering propellers. Three versions of the Trislander are the BN-2A Mk 111-2 (a standard version with extended nose baggage compartment), the BN-2A Mk 111-3 (with an automatic feathering system for the props), and the BN-2A Mk 111-4 (with a rocket engine for additional thrust if an engine fails on takeoff).

 

Gallery

 

Britten Norman BN-2 Islander (1968)
Powerplant: two Lycoming O-540-E4B5, 260 bhp
Propellers: Hartzell constant-speed feathering two-blade 80 in diameter.
Wingspan, 49 ft
Length, 35 ft 71 in
Height, 13 ft 8 in
Gross wing area, 325 sq.ft
Max. usable floor area, 43.4 sq.ft
Max. usable cabin volume, 140 cu.ft
Max. cabin length, 160 in including flightdeck
Max. width, 43in
Max, height, 51 in.
Accommodation: max. high density seating 9 passengers and pilot at 30 in pitch
Basic operational weight, 3280 lb
Total fuel, 800 lb
Max. take-off, 5500 lb
Max. landing, 5500 lb
Max. payload (volume limited), 1920 lb
Max. zero fuel, 5200 lb
Power loading (max. take-off weight), 10.6 lb/hp
Wing loading (max. take-off weight), 16.95 lb/sq.ft
Wing loading (max. landing weight), 16.95 lb/ft
High-speed cruise, 138 kt. at 6500 ft
Long-range cruise, 132 kt. at 13,000 ft
Approach speed, 62 kt
Take-off field length, ISA at sea level, 1000 ft
Landing field length, ISA at sea level, 990 ft
Range with allowances, max. fuel, 1450 lb payload, 738 nm


BN2A-8
Engine: 2 x Lycoming O-540-E4C5, 260 hp.
Seats: 10.
Wing loading: 19.6 lb/sq.ft.
Pwr loading: 12.7 lb/hp.
Gross wt: 6200 lb.
Empty wt: 3400 lb.
Equipped useful load: 2449 lb.
Payload max fuel: 1633 lb.
Range max fuel 75% pwr: 564nm/4hr.
Range max fuel 55% pwr: 625nm/5.3hr.
Service ceiling: 13,000 ft.
75% cruise: 139 kt.
55% cruise: 119 kt.
Vmc: 39 kt.
Stall: 44-50 kt.
1.3 Vso: 57 kt.
ROC: 950 fpm.
SE ROC: 170 fpm @ 65 kt.
SE service ceiling; 4450 ft.
Min field length: 1160 ft.
Fuel cap: 816 lb.

BN2A-9
Engine: 2 x Lycoming O-540-E4C5, 260 hp.
Seats: 10.
Wing loading: 20.3 lb/sq.ft.
Pwr loading: 12.12 lb/hp.
Gross wt: 6,300 lb.
Empty wt: 3250 lb.
Equipped useful load: 2699 lb.
Payload max fuel: 1523 lb.
Range max fuel/75% pwr: 856nm/6.1hr.
Range max fuel / 55% pwr: 934nm/7.9hr.
Ceiling: 13,000 ft.
75% cruise: 139 kt.
55% cruise: 119 kt.
Vmc: 39 kt.
Stall: 44-50 kt. 1.3
Vso: 57 kt.
ROC: 950 fpm.
SE ROC: 170 fpm @ 65 kt.
SE ceiling: 4450 ft.
Min field length: 1160 ft.
Fuel cap: 1176 lb.

BN-2A-20
Engine: 2 x Lycoming IO-540-K1B5, 300 hp.
Seats: 10.
Wing loading: 19.6 lb/sq.ft.
Pwr loading: 11 lb/hp.
Gross wt: 6560 lb.
Empty wt: 3640 lb.
Equipped useful load: 2569 lb.
Payload max fuel: 1753 lb.
Range max fuel
75% pwr: 534nm/3.6hr.
Range max fuel 55% pwr: 609nm/4.7hr.
Service ceiling: 18,000 ft.
75% cruise: 147 kt.
55% cruise: 131 kt.
Vmc: 39 kt.
Stall: 44-50 kt.
1.3 Vso: 57 kt.
ROC: 1130 fpm @ 57 kt.
SE ROC: 225 fpm @ 75 kt.
SE service ceiling; 3,100 ft.
Min field length: 1100 ft.
Fuel cap: 816 lb.

BN-2A-21
Engine: 2 x Lycoming IO-540-K1B5, 300 hp.
Seats: 10.
Wing loading: 20.3 lb/sq.ft.
Pwr loading: 11 lb/hp.
Gross wt: 6600 lb.
Empty wt: 3695 lb.
Equipped useful load: 2554 lb.
Payload max fuel: 1378 lb.
Range max fuel
75% pwr: 799nm/5.4hr.
Range max fuel 55% pwr: 924nm/7.1hr.
Service ceiling: 18,000 ft.
75% cruise: 147 kt.
55% cruise: 131 kt.
Vmc: 39 kt.
Stall: 44-50 kt.
1.3 Vso: 57 kt.
ROC: 1130 fpm.
SE ROC: 225 fpm @ 75 kt.
SE service ceiling; 3,100 ft.
Min field length: 1100 ft.
Fuel cap: 1176 lb.

Britten-Norman BN-2A-21 Maritime Defender
Engines: 2 x Avco Lycoming IO-540-K1B5, 300 hp
Length: 36.319 ft / 11.07 m
Height: 12.402 ft / 3.78 m
Wingspan: 53 ft ft / 16.15 m
Wing area: 342.295 sq.ft / 31.8 sq.m
Max take off weight: 6593.0 lb / 2990.0 kg
Weight empty: 4013.1 lb / 1820.0 kg
Max. speed: 157 kts / 290 km/h
Cruising speed: 148 kts / 274 km/h
Service ceiling: 18045 ft / 5500 m
Endurance (2 x 56 Imp.Gal. drop tanks): 15 hr.

BN2B
First built: 1967.
Engine: 2 x Lycoming O-540-E4C5, 260 hp.
TBO: 2000 hrs.
Prop: Hartzell 2 blade, constant speed 80 in.
Seats: 10.
Length: 35.7 ft.
Height: 12.4 ft.
Wingspan: 49 ft.
Wing area: 325 sq.ft.
Wing aspect ratio: 7.4.
Max ramp wt: 6600 lbs.
Max take off wt: 6600 lbs.
Standard empty wt: 3612 lbs.
Max useful load: 2988 lbs.
Max landing wt: 6300 lbs.
Wing loading: 20.3 lbs/sq.ft.
Power loading: 11 lbs/hp.
Max useable fuel: 1176 lbs.
Climb rate: 1130 fpm @ 65 kts.
Climb gradient: 1043 ft/nm.
Rate of climb @ 8000 ft: 550 fpm.
Service ceiling; 18,000 ft.
SE rate of climb: 225 fpm @ 62 kts.
SE climb gradient: 218 f/nm.
SE ceiling: 7000 ft.
Max speed: 139 kts.
Cruise @ 65% power @ 8,000ft: 135 kts.
Fuel flow @ 65% power @ 8,000ft: 160 pph.
Endurance @ 65% power @ 8,000ft: 7.1 hr.
Stalling speed clean: 49 kts.
Stall speed gear/flaps down: 42 kts.
Turbulent air penetration speed: 107 kts.
Fixed undercarriage.
Wing load: 19.27 lb/sq.ft / 94.0 kg/sq.m
Maximum range: 1134 nm / 2100 km
Crew: 2+2
Payload: 8Pax / 1015kg

BN-2T
Engines: 2 x Allison 250-B17C

Turbine Defender
Engine: 2 x Allison 250 600 kW, 480 kW.
Span: 14.9 m.
Length: 10.9 m.
Wing area: 30.2 sq.m.
Empty wt: 1914 kg.
MTOW: 3175 kg.
Payload: 1270 kg.
Cruise speed: 285 kph.
Initial ROC: 320 m / min.
Ceiling: 7620 m.
T/O run: 225 m.
Ldg run: 228 m.
Fuel internal: 814 (+454) lt.
Range: 1350 km.
Capacity: 10 pax.

Britten-Norman BN2T-4S Defender 4000
Engines: 2 x Allison 250-B17F/1 turboprop, 400 shp
Props: 3 blade, 80 in.
Length: 35.86ft (10.93m)
Width: 48.98ft (14.93m)
Height: 13.78ft (4.20m)
Maximum Speed: 225mph (362kmh; 195kts)
Max cruise: 178 kts
ROC: 1210 fpm.
SE ROC: 223 fpm
Maximum Range: 437miles (703km)
External Fuel Tanks capacity: 2,500lbs
Accommodation: 2 + 6
Hardpoints: 4
Empty Weight: 4,998lbs (2,267kg)
Maximum Take-Off Weight: 8,499lbs (3,855kg)

AEW Defender

Engines: Allison turboprop, 375 shp.
Endurance: 6 hr.
Operating speed: 90-150 kts.

 

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