Flight test: Britten-Norman BN-2 Islander
PUBLISHED: 11:06 15 December 2017
The infinitely versatile 'flying Land Rover' handles more like a light single than a feeder-liner and freight-hauler. Words by Dave Unwin and photos from Jamie Hunter via Britten-Norman
Turning on to final, it’s hard to reconcile the briefed Vref (landing reference speed) of 56 knots with the four rows of seats behind me. I can only be flying an Islander!
There are very few types that remain in production more than fifty years after they first flew, and Britten-Norman’s Islander is not only an iconic machine, it’s also one of the most successful British aircraft ever made.
Designed by John Britten and Desmond Norman, it 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 proven itself 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, capable of producing either 320 or 400hp each.
Presented with an opportunity to put the Islander through its paces, I find myself at B-N’s Lee-on-the-Solent assembly facility in the company of 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. In a busy hangar, Simon points out the aircraft’s salient features.
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 version, which is quite luxurious), it’s a functional, utilitarian machine.
An all-metal high wing monoplane of entirely conventional design and construction, the one-piece cantilever wing is riveted to the spar torsion box structure and has no dihedral and just two degrees of incidence, while the wingtips have a slight upsweep. 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°) and Down (56°).
An excellent example of the design logic applied to the Islander−where form clearly followed function−is in the location of the engines. As they’re mounted up on the high wing, prop clearance is excellent, while 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 the pilot, although the proximity of the engines to the fuselage means the cabin can be rather noisy. On this example power comes from a pair of Lycoming IO-540 air-cooled flat sixes, which produce 300hp each and 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 aircraft is fitted with piston engines, the answer is simple. Turbines are wonderfully reliable powerplants, but they do have one significant drawback−it’s not the hours that wear them out, but the cycles (being started up and shut down). Like many Islanders, this particular aircraft will be used mostly on short, high-frequency services, hence 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 imagine. 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. Parker Hannifin disc brakes are fitted to the main wheels 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° it disengages automatically and becomes free-castoring, giving the aircraft an incredibly tight turning radius of under ten metres.
The wheel track is also commendably wide, giving good stability on the ground, but the main undercarriage struts are quite long and, although they would clearly soak up vertical and longitudinal loads with aplomb, they’re possibly not quite so tolerant of lateral loads. I make a note that it’s probably best not to land with any drift on.
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 reconfigured for different roles. It can even be used as a crop-sprayer or for oil 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 loading freight easy.
The cabin doors are complemented by a pilot’s door on the port side, an arrangement I 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 is 5.2 cubic metres and can accommodate up to a tonne 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). Secondly, in situations without ground crew, pilots prefer to check personally that the doors have been shut and locked correctly.
With Simon in the other seat I take stock of the cockpit. The seat and pedals both adjust (which I like), although I notice that the rudder pedals seem ever-so-slightly offset in relation to the control yoke. The harness is of the three-point type (which I don’t like). A four-point harness is an option I’d go for: I feel quite strongly that the pilot’s seat should always be fitted with adequate restraints−in severe turbulence, a three-point inertial-reel system simply isn’t enough.
I like the overall cockpit layout. The instrument panel is clean and uncluttered−the dual screens of the Garmin G600 multi-function display (MFD) are directly in front of the pilot, with the excellent JP Instruments’ (JPI) EDM 960 engine monitoring system in the centre of the panel and the GTN 650 and 750 navigation/communications unit on the right.
As the Islander is very much a single-pilot aircraft I think the latter should be mounted in such a way that it’s angled slightly towards the pilot. This would reduce parallax while also making the touchscreen easier to operate in turbulence.
The standby analogue airspeed indicator (ASI), attitude indicator and altimeter are arranged in a row beneath the G600 and, while this layout is acceptable, in my view they’d be better in a column to the left of the MFD. An even better solution would be an Aspen Avionics EFD-1000 ‘Evolution’ standby instrument or similar−an entirely self-contained unit (it even has an integral battery) that provides airspeed, altitude, attitude and navigation information.
As well as being an easier system to use, it would also allow BN to delete the vacuum pump, suction gauge and associated plumbing. 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 seemed a little excessive to me 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 carries the throttle, prop and mixture levers for each engine, with the flap switch directly underneath, and then the park brake and (redundant) carb heat controls. 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. I like the layout of the electrical switches.
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. The switches, which are mostly large toggles, are robust−another plus point−but I did wonder if perhaps they would be better colour-coded (they’re all a somewhat anonymous silver). All the circuit breakers are on the other side of the panel, easy to see and−more importantly−reach.
Both engines start readily and we’re soon taxying out. The throttle levers are surprisingly stiff, and I automatically check the friction lock, even though Simon has already explained that they aren’t set up quite right. In fairness, this particular aircraft is still in pre-delivery flight test, and I’m sure that it will be sorted before being released to service.
It’s a little surprising that such items still need tweaking as B-N has produced more than 1,250 Islanders over the last five decades. However, unlike cars each example is hand-built.
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. Having ensured that the nosewheel steering has automatically re-engaged I carry on to Solent Airport’s Runway 23. With only Simon and me aboard and full fuel we are around 700kg below the maximum all-up weight (MAUW) of 2,994kg. The airfield is essentially 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 very straightforward, so I carefully position the Islander on the centreline and push the too-stiff throttles open. The acceleration is excellent, and as the speed sweeps imperiously past 55kt I initiate a gentle rotation.
The Islander practically leaps off the runway and climbs away at just over 1,200ft/min 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 just a very subtle change in pitch which is easily trimmed out, and we soar up into the summer sky above the sparkling Solent. 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 actually a little heavy, although I soon get used to them. Levelling out at 4,000ft I begin to examine the Islander’s forte−slow flight and stalls. The wing retains a tenacious grip on the air and, with flaps selected up, the aircraft stalls at a creditable 44kt. This drops to a remarkable 36 with the flaps down. The stall warner (there’s 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 in this fashion, 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 and control 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 it would not be a hard aircraft to fly on instruments.
Having spiralled down to 3,500ft, 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 (remember we are 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.
Having slowly brought the power back up on the port engine, I set 24/24 (24in of manifold pressure and 2,400rpm), trim forward carefully and concentrate on holding the aircraft exactly level at 2,500ft while Simon helpfully 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 lph.
With everything else on the flight test card ticked off, it’s time to head back to Solent Airport for some circuits. As the runway here is 1,309m of smooth tarmac, it’s not really representative of an Islander’s natural environment. I really wish we could try a few farm strips, but there just isn’t time.
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 65kt (Vmca−minimum control speed with the critical engine out) until very short final.
I select the first stage of flap on base and full flap on final, but delay pushing the props up to ‘Max RPM’ to keep the noise down.
Speed control is easy all the way round the circuit but I flare slightly too high and the touchdown is ‘firm but fair’. “The undercarriage struts are long, but not that long,” laughs Simon, before allowing that the Islander is a little “stiff-legged”.
As briefed this is a touch-and-go, and almost as soon as the throttles hit the stops we’re airborne again. As the second landing is a significant improvement on the first, I elect to retract the flaps fully for the next departure. Such is the Islander’s excellent performance that I really can’t discern any noteworthy difference in the takeoff run.
As we turn crosswind I’m very pleased when Simon compliments my handling. “I like how you fly,” he observes, “very low gain.” “That’s one way of putting it,” I laugh, “I guess ‘lazy’ is another.”
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 56kt 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 very 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 56, but the touchdown point is further up the runway than I intended. It almost feels as if it could use a little more flap, but there is practically no wind.
Landing in a strong headwind must be great sport: I imagine you can practically hover the Islander onto the runway (which is quite apposite, bearing in mind Simon’s impressive CV of twenty years in the Royal Navy flying the V/STOL Sea Harrier and, as a test pilot, he was involved in the fifth-generation Lockheed Martin X-35 programme).
Round we go again and this time on very short final I sense the sink rate building so try to add a squeeze of throttle just as Simon says, “a little power”. The throttles don’t move and as Simon says “power” with a bit more urgency, I push the levers harder, the engines roar and in a heartbeat we’re flying again−damn those stiff throttles!
My next attempt is much better, so as soon as the wheels 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 after a surprisingly short run. 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 easy to see why it’s still in production, more than fifty years after it first flew. It may look like a very simple aircraft, but this belies a very clever design. Anyone can design something complicated, but as Leonardo da Vinci observed ‘simplicity is the ultimate sophistication’.
For a short-haul feeder-liner or freighter, hopping from island to island, it’s difficult to imagine a more capable machine. In many respects, you could say that this aeroplane does exactly what its name implies.