November 14, 2019

July 25, 2019

Please reload

Recent Posts

ZS-OFH gets her Prop Overhauled

July 21, 2017

1/10
Please reload

Featured Posts

The Britten-Norman BN-2 Islander

 

Off-road Champion The B-N Islander

 

 

 

 

There are very few types that remain in production more than fifty years after they first flew. Britten-Norman’s Islander is one of them and it’s not only an iconic machine, it’s also one of the most successful British aircraft ever made.

 

designed by John Britten and Desmond Norman, the Islander was initially intended for short-haul, high-frequency commuter operations but has subsequently been adapted for a wide variety of roles, both civilian and military. The BN-2 has proved to be an excellent feeder-liner and has long been a favourite with freight companies, parachute schools, air ambulance operators, and the military.

Isle of Wight-based B-N has built and delivered more than 1,250 Islanders since the type first flew in June 1965, with examples now operating in over 120 countries. It is currently available in several different variants, powered by either 260 or 300 horsepower Lycoming piston engines, or Rolls-Royce turboprops, of either 320 or 400hp.

Presented with an opportunity to put the Islander through its paces, we pitched up at B-N’s Lee-on-the-Solent assembly facility to meet test pilot Simon Hargreaves. The test aircraft is the latest example to come off the production line. It is configured as a feeder-liner capable of carrying up to nine passengers, and will shortly be delivered to a regional carrier in mainland Europe.

 

The Walk Around

In many respects the Islander can be compared to a flying Land Rover, even down to the boxy cabin. Bereft of frills or superfluities (except for the Executive option, which is luxuriously appointed), it’s a functional, utilitarian aircraft.

The one-piece cantilever wing has no dihedral and just two degrees of incidence. The trailing edge consists of cable-operated slotted Frise ailerons fitted with mass balances, and large electrically-actuated slotted flaps which have three settings: Up, T/O (25 deg) and Down (56 deg).

The engines are high so prop clearance is excellent, and being close to the aircraft’s centreline means the minimum controllable airspeed on one engine (Vmca) is very low. This is a good thing for safety, although the proximity of the engines to the fuselage means the cabin can be rather noisy. On our test aircraft, the power is from a pair of 300 hp Lycoming IO-540s, which turn Hartzell constant-speed fully feathering ‘Scimitar’ props. They are fed from wing tanks (one in each wing) with a combined capacity of 492 litres. Tip tanks can be fitted as an optional extra, increasing capacity to 814 litres.

For those of you wondering why a brand new commuter aircraft is fitted with piston engines, the answer is simple. Turbines are wonderfully reliable powerplants, but they have one significant drawback − it’s not the hours that wear them out, but the cycles (being started up and shut down). Like most Islanders, this particular aircraft will be used primarily on short, high-frequency services, so its operator has opted for the Lycomings.

The Islander is certified to fly from unimproved landing strips (including beaches) and consequently the fixed undercarriage is every bit as rugged as you’d expect. It consists of a large single nosewheel, while the twin main wheels are attached to a streamlined strut that connects to the wing behind each engine nacelle. The main wheels have disc brakes and all three undercarriage units have oleo shock absorbers. Notably, all five wheels use the same size tyre − ideal for operation from rudimentary airstrips where access to spares may be limited.

Interestingly, although the nosewheel steers through the rudder pedals, beyond 45 deg it disengages automatically and becomes free-castoring, giving the aircraft an incredibly tight turning radius of under ten metres.

The tail consists of a big, slightly swept fin and large rudder, fixed tailplane and mass-balanced elevator. The rudder and elevator are actuated by a combination of pushrods and cables and both are fitted with trim tabs. The elevator feels very heavy on the ground, but soon lightens up when the air starts flowing over it.

The square-section cabin and flat floor allow the aircraft to be quickly re-configured for different roles. It can even be used as a crop-sprayer or for oil slick dispersal, as underwing hardpoints allow spray booms or external pods to be carried. Access to the cabin is via doors on both sides of the fuselage, with an additional cargo door to port. Sliding doors for special missions, paradropping or simply for improved access are an option, and the low door sills make cargo loading easy.

 

The Interior

The cabin doors are complemented by a pilot’s door on the port side, an arrangement we like for several reasons. If you’re using the aircraft as a freighter you can fill the cabin to capacity without having to leave space for an aisle. The cabin can accommodate up to 1,000 Kg of freight but, like most small freighters, it will often ‘bulk out’ (run out of space) before it ‘grosses out’ (runs out of weight-carrying capacity). Also, in situations without ground crew, pilots prefer to check personally that the doors have been properly shut and locked.

The seat and pedals both adjust and we both like the overall cockpit layout. The instrument panel is clean and uncluttered − the dual screens of the Garmin G600 are directly in front of the pilot, with the excellent EDM 960 engine monitoring system in the centre of the panel and the GTN 650 and 750 nav/comms unit on the right. The standby ‘steam gauges’ are arranged in a row beneath the G600. To the right of the altimeter is an annunciator panel, while above the G600 are digital displays for each engine’s manifold pressure and rpm. This may seem a little excessive as this information is clearly presented on the EDM 930 display, but it’s part of the standard JPI set-up.

A large central pedestal houses the throttle, prop and mixture levers for each engine, the flap switch directly underneath, with the park brake below. Three lights between the G600 and JPI screens show flap position.

Interestingly, the Islander is not equipped with cowl flaps. While the rudder trimmer is in the roof, curiously the large elevator trim wheel is mounted on the starboard side of the pedestal (i.e. away from the pilot). Both are purely manual.

The layout of the electrical switches is excellent. The magnetos, boost pumps and starter switch are contained in a neat panel above the windscreen, with all the others below the pilot’s panel-mounted yoke. All the circuit breakers are on the other side of the panel, easy to see, and more importantly, to reach.

 

Flying the Islander

The field of view is excellent, and the combination of powerful progressive brakes, differential thrust and a steerable nosewheel make the Islander very easy to manoeuvre on the ground. Simon encourages me to force the nosewheel into ‘castor’ and then, with a dab of brake and some differential thrust, the aircraft simply pivots around the main wheels. I’m quite timid with this (as I don’t want to scrub the tyres) but can clearly see just how easy a 180° turn on a narrow airstrip could be.

With three aboard and full fuel we are around 700kg below the maximum all-up weight (MAUW) of 2,994kg. The airfield is near as dammit at sea level and the temperature is 17°C so the ambient conditions are very close to ISA with a gentle breeze down the runway.

The pre-takeoff checks are straightforward, so I carefully position the Islander on the centreline and push the throttles open. The acceleration is excellent, and as the speed sweeps imperiously past 55knots, I initiate a gentle rotation.

The Islander practically leaps off the runway and climbs away at just over 1,200fpm and 70kt. During the pre-flight briefing, Simon explained we’d probably get a ‘propeller overspeed’ caution just after takeoff, and we did. This wasn’t a malfunction. In order to keep the noise down, the system is designed to warn the pilot when the rpm goes above 2,600 and, in this instance, the governors which maintain a given rpm were yet to be set up correctly for the Scimitar propellers.

Retracting the flaps causes a small change in pitch which is easily trimmed out. As we climb I try a few gentle turns and this confirms what I’d expected − this is a very stable aeroplane. The ailerons are a little heavy, although I soon get used to them. Levelling out at 4,000ft I examine the Islander’s forte − slow flight and stalls. The wing retains a tenacious grip on the air and, with flaps up, the aircraft stalls at a creditable 44kt. This drops to a remarkable 36kt with the flaps down. The stall warning (a horn and a light) activates about five knots above critical alpha, and when the wing finally does quit flying it always breaks straight ahead. For the final stall I set takeoff flap, open the throttles and just keep hauling the nose up… and up… and up!

A full power departure stall can often bring out the worst in an aeroplane, but the Islander is so well mannered that even when it is being roundly abused, nothing unpleasant happens. The ASI’s speed tape sinks to an incredible 33kt (and remember, our weight is still around 2,200kg) before the Islander reluctantly pitches down and the wing instantly starts flying again.

This is an incredibly docile aircraft.

Moving onto stability tests confirms that, although there is plenty of control, the designers have placed even more emphasis on stability. The Islander’s stick-free stability is strongly positive longitudinally and directionally, and weakly neutral laterally. Overall it is very docile, and easy to fly on instruments.

Simon sets zero thrust on the port engine to simulate a feathered prop and I assess the single-engine performance and controllability. At 65kt, half a ball out on the turn and slip indicator and a few degrees of bank into the ‘live’ engine, the climb rate is a perfectly acceptable 300fpm at 3,500ft and the aircraft is eminently controllable. I’ll confess that I don’t find the operation of the roof-mounted rudder trimmer intuitive initially, but soon get the hang of it.

With the power back up on the port engine, I set 24/24 and concentrate on holding the aircraft level at 2,500ft while Simon notes down the speed and fuel flow: The IAS of 128kt means a TAS of 133kt, while the fuel flow is about 45 litres per hour on each side. Pulling the power back to 21/21 the speed dips to 114 IAS (119 TAS) while the total fuel flow reduces to around 80 litres per hour.

We head back for some circuits. As the runway is 1,309m of smooth tarmac, it’s not really representative of an Islander’s natural environment. As the circuit direction for Runway 23 is right-hand and I’m in the left seat, positioning could be a little tricky in some aircraft, but the field of view is excellent and I have no problem judging when to turn base. For my first landing I fly a conventional approach, ensuring that I keep the speed above the 65kt Vmca until very short final.

Speed control is easy all the way round the circuit but I flare slightly too high and the touchdown is ‘firm but fair’. As briefed this is a touch-and-go, and almost as soon as the throttles hit the stops we’re airborne again.

Turning downwind Simon briefs me to make this a STOL (short takeoff and landing) approach, which entails getting full flap down a little earlier and trimming for 56kts on final. We are now using a ‘back side’ technique, where speed is controlled completely with pitch, while power controls the descent rate. Simon emphasises that accurate speed control is important, and that I might just need a suggestion of power in the flare to cushion the touchdown.

The aircraft is so speed-stable that I have no trouble at all nailing the speed tape to 56kts, but the touchdown point is further up the runway than I intended. As soon as the mainwheels touch, I lower the nose and brake firmly to a stop. We don’t use much runway. It’s worth mentioning that I only had an hour on type; a bit more practice and a decent wind on the nose and I’m sure I could get the Islander down and stopped in a very short distance. The pilot’s operating handbook claims a stopping distance of only 299m when landing over a 50ft obstacle.

Now for a STOL takeoff. With flaps set to 25°, I run the engines up to full power against the brakes and then release them. The acceleration is excellent, and as the speed tape hits 50 I pull the nose up and the Islander leaps off the ground. On the following landing I hold the nose up for aerodynamic braking and roll almost to the end of the runway with the nosewheel still in the air, such is the power of the elevator.

It’s hard not to be impressed by the Islander, and it’s easy to see why it’s still in production after more than fifty years. It may look like an elementary aircraft, but this belies a very clever design. Anyone can design something complicated, but as Leonardo da Vinci observed ‘simplicity is the ultimate sophistication’.

 

Perfect for Africa

The Islander is an honest aeroplane that is ideally suited to African conditions. It’s no great shakes in the glamour and glitz arena, but when it comes to flying into and out of goat tracks with heavy loads and nine pax, I reckon there are very few aircraft that could beat it. Its STOL capabilities are legendary and it will get into, and out of, tight, unlikely spots with a good load aboard.

I first met the Islander back in the 70s at Wings Airways in the USA, when we were running a high-density shuttle service from peri-urban areas into Philadelphia’s KPHL. The legs varied from as little as around 10nm up to 60nm and the runways were, at best, grass strips.

My days consisted of a hub and spoke run, where I would begin at a field, fly a load of pax to KPHL, then fly to another airfield to collect another load for KPHL and so on – on some legs, I wouldn’t even bother to get the flaps up. This was pure high-cycle feeder flying with often more than ten cycles a day, and the Islander thrived in this environment, never once did it let me down.

The runways, which rarely deserved that title, could become interesting mud slides in autumn, hair-raising ‘skating rinks’ in winter, cracked, potholed minefields in spring and hot and dusty in summer. But the ‘boom-box’ – as we sometimes jokingly called the Islander – took it all in its stride without any incidents.

 

Conclusion

Earlier, we referred to the Islander as a “flying Land Rover” and in the same way that the no-frills Land Rover first opened up Africa to tourism decades ago, so the Islander is perfectly positioned to provide the next step of becoming the vehicle that opens up Africa’s population to air travel. In addition, its multi-role capability allows it to be configured for many missions throughout Africa where low acquisition cost, ruggedness, STOL capability and reliability are key objectives.

Although in recent years turbine aircraft such as the Kodiak and Caravan have eclipsed the Islander, the threat to Avgas availability has receded and the Islander is still a great contender for Okavango and Mozambique Island destinations and for relief operations such as Mission Aviation Fellowship flies.

The Islander’s piston engines make acquisition and operating costs significantly less and give passengers the comfort of two engines. It is interesting to note that its most significant competition will be the still in development Tecnam P2012. With the same high wing and fixed gear configuration, and with two 375 hp Lycomings, the new Italian may be faster, but it is almost certainly not going to be as rugged – and it costs nearly twice as much.

While the Islander may be slower than its more powerful turbine competitors, over short sectors the speed difference is negligible, and operating costs per seat are about a third less. There’s still a lot to recommend this functional classic.

 

Share on Facebook
Share on Twitter
Please reload