Flight test: Sherwood Scout
PUBLISHED: 13:37 06 August 2019 | UPDATED: 13:48 06 August 2019
The versatile, British-manufactured sport aircraft delivered ready to fly or build yourself, with handy folding wings, various engine options, and nose- or tailwheel as the fancy takes you | Words: Dave Unwin - Photos: Keith Wilson
As Keith and I cruise comfortably along the north Norfolk coast, it occurs to me that we've flown together a lot over the last eight years−in everything from SSDRs to Strikemasters−but this is the first time we've been in the same aircraft!
We'd travelled to The Light Aircraft Company's delightful airfield of Little Snoring in Norfolk on a 24-carat gold-plated forecast of good weather. Except that, when we arrived, it wasn't−and certainly no good for air-to-air photography.
However, gentleman that he is, TLAC boss Paul Hendry-Smith insists that Keith and I take the Sherwood Scout for an hour, so that I can at least fly off most of the items on the flight test card. He also says I can sample the SSDR KUB if there's time, and I feel it'd be discourteous to decline such a generous offer…
After a look around TLAC's very impressive and busy facility, which has myriad KUBs, Rangers and Scouts in various assembly stages TLAC's Chief Pilot James Milne introduces us to the test aircraft, Golf Charlie Lima Alpha Kilo.
A handsome high-wing, side-by-side two-seater, the Scout can trace its lineage as far back as 1983, when the Avid Flyer was first introduced. The basic design was also to be used for the Denney Kitfox, Rocky Mountain Ridge Runner and the Flying K Sky Raider.
The latter morphed into the Just Aircraft Escapade which−after a long and complicated gestation−was marketed in the UK by the late Terry Francis as the Reality Escapade. When TLAC bought the design in 2013 the first thing Paul and his team did was implement a significant number of improvements to both its design and construction.
To be honest, the Escapade had a somewhat unsatisfactory reputation for poor handling due to a combination of relaxed stability, inadequate pitch control and considerable adverse yaw produced by excessive aileron drag.
After a year of flight testing various revisions they enlarged both the elevator and rudder, cleaned up the junction between the wing root and flaps, added gap seals and implemented several other aerodynamic tweaks. Renamed the Sherwood Scout, TLAC currently market it as either a ready-to-fly factory-built microlight or as a kit, or 'Fast-Build' kit for both ULA or VLA versions.
The overall construction is TIG-welded 4130 steel tube, while the wings use aluminium spars and plywood ribs. The fuselage, wings and tail are all covered with Oratex and power can be supplied by either the 80hp or 100hp Rotax 912 or 912S, 85hp Jabiru 2200, 95hp UL260i or 95hp D-Motor.
It can be configured with either a tricycle or tailwheel undercarriage (converting takes only two hours). It's fitted with wings that can be quickly and easily folded aft (well-practiced Paul can fold both wings in two minutes) with−crucially−no control disconnection needed, reducing the span from almost nine metres to only 2.4m (the legal road towing width).
I've always been a keen advocate of folding wings for sport aircraft. With the exception of airliners, most aircraft spend a lot more of their time on the ground than in the air. Of the 8,760 hours in a year, I'd bet most GA aircraft spend 95% on the ground.
Remember that hangarage represents a significant part of the cost of running an aircraft, and hangarage is charged by the amount of space used. An aircraft that can reduce its span to less than three metres must be a good thing−and this is not a new idea.
In fact, when the Daily Mail sponsored a series of light aeroplane trials at Lympne in the early 1920s, part of the specification required the aircraft to be able to pass through a narrow triangular wooden frame.
Consequently, in the 1930s popular sportplanes like the Avro Avian, BA Swallow and de Havilland Gipsy Moth all had folding wings.
Of course this technology is quite mature because, as well as many types of sportplane, literally thousands of naval aircraft feature folding wings, from the Wildcat to the Tomcat.
The folding mechanism does add both weight and complexity (two things that Light Sport Aircraft designers generally try to avoid), but is the trade-off in this instance worth it, and does the wing-fold mechanism add that much weight and complexity? I was looking forward to finding out.
Therefore, instead of starting my inspection at the spinner (as I usually do) I began the pre-flight with a briefing on the wing-fold mechanism. This seemed very well designed and the procedure for folding the wings perfectly straightforward.
The constant chord wings are braced by vee-struts, with about half of the trailing edge taken up by the large, single-slotted mechanically-actuated flaps. These have four positions, 0°, 10°, 25° and 40°. The ailerons extend out to the cambered tips, which feature large LED position lights.
The tail consists of a very slightly swept-back fin and large rudder, a tailplane braced by a combination of struts and wires, and separate elevators. The ailerons and elevator are operated by mixture of pushrods, bellcranks and cables, while the rudder uses cables alone. Longitudinal trim is provided by a large tab set into the trailing edge of the port elevator.
The main undercarriage has bungees for shock absorption and is fitted with fat tundra tyres and slotted hydraulic disc brakes. The pneumatic tailwheel steers through the rudder pedals up to about 30° each way; beyond that it 'breaks out' and castors. The alternative nosewheel free-castors, steering being provided in this configuration by differential braking.
The test aircraft was powered by the 100hp Rotax 912ULS, turning a composite three-blade fixed-pitch propeller. There is a hatch on the top of the cowling through which it is possible to check the oil but not the coolant.
This is a shame as the ability to check both the oil and coolant levels without removing the cowling is, in my opinion, an excellent design feature. The Scout's fuel is carried in two 35-litre metal tanks located in the wings that feed a fuselage-mounted four-litre header tank, giving a total capacity of 74 litres. A pair of fifty-litre long-range tanks is an option.
Access to the cockpit is good. The front-hinged doors are enormous (opening through a full 180°) and the sills nice and low. The doors are skinned with Perspex, and the top half hinges upward. If it's warm you can fly with the top half open, or simply remove the entire door! With Keith in the other seat and securely strapped down by a sturdy Willians four-point harness, I hop in and begin to familiarise myself with the controls and instruments.
With a maximum width of 113cm the cockpit is quite wide, and the extensive glazing gives it a very airy feel. The baggage bay behind the seats has an impressive volume of 500 litres, and its open floor area can take up to 35kg.
Unusually for an aircraft in this class the seats adjust. They are secured in position with a positive locking pin and I like the neat safety strap. In another indicator of the high build spec there are toe brakes for both pilots.
The tall, slightly curved sticks feel very natural, while levers for the flaps and trim are between the seats. A plunger-type throttle is mounted centrally just below the instrument panel and in easy reach of the P1 or P2.
The flight and engine instruments are a mixture of analogue and digital: an MGL Discovery-Lite IEFIS which shows both flight and engine information (and even synthetic vision) with the analogue ASI and altimeter to its right.
Avionics (Trig transceiver and transponder) are mounted in the centre of the panel along with the circuit breakers and electrical switches, and analogue oil pressure and temperature, coolant temperature and voltmeter on the right. On the left is the Master and a key-operated rotary unit for the mags and starter.
It's all neatly and logically laid out, with very little to criticise. However, with the flaps deployed the trim lever isn't quite so accessible, and as fuel quantity remaining is only shown by sight-tubes in the wing roots (which are difficult to read 'at a glance'), there should be clear scales behind the sight-tubes, with preferably some sort of float within them.
I'd also like to see a 'Fuel Low' light that illuminates when the header tank starts to empty. The light that shows when the electric carb heat is on is also the wrong colour. It's red, and red lights in cockpits generally mean something isn't right. The general finish is also a little bit basic (there are a lot of exposed wires and cables, which James described as "Series One Landrover") but TLAC is already on the cosmetics case.
The 912 starts easily (it is fitted with the 'soft start system') and runs smoothly, but I am soon reminded of what must be the worst feature of any nine-series Rotax: the ridiculously powerful throttle springs. These are arranged to give full power should the throttle cable break so, unless you have the throttle friction wound on hard, the second you let go of the throttle that's what happens.
Of course, like most of us I generally keep my hand on the throttle when I'm on the ground, but even briefly setting the flaps, adjusting the trim, or any other task, can have the engine accelerating alarmingly quickly. While if the friction is screwed right in, you have no finesse.
With the minimal pre-takeoff checks complete and 25° of flap set I line up on Runway 25 and bring the power in. I wouldn't describe Keith and me as 'overweight', more 'under-height', but even with full tanks we're still about 20kg below the 499 MAUW.
Ambient conditions are slightly above ISA, with an airfield elevation of 196ft and an OAT of 19°C. There's about ten knots on the nose, the grass is short and the acceleration excellent. I doubt we used even the first 100m of the 850 available. The climb rate was equally impressive, the Vy of 55kt producing around 900fpm.
After a brief transit to the coast, I start my assessment with general handling.
A couple of steep turns and reversals reveal crisp, authoritative controls with delightfully pleasant stick forces. The control circuits all seemed agreeably light and reasonably frictionless, with low breakout forces, and control around all three axes is very good, the roll rate being particularly noteworthy. It's fun to fly.
Visibility in the turn−and indeed every phase of flight−is very good for a high-wing aircraft. Exploring the overall stability indicates it to be strongly positive longitudinally, weakly positive directionally and positive laterally. Slowing down to examine the stall confirms what I already suspected−this is a very well-mannered flying machine.
As the flaps extend they produce a very slight nose-down pitching moment that is easily trimmed out. There is no artificial, or even natural, stall warning but the speeds are so slow and the deck angle so high that it's obvious that something isn't going well.
With any flap deployed, and irrespective of the power setting, it always breaks straight ahead, although with the flaps fully up it does have a slight tendency to drop the port wing. With full flap and a hint of power we get the IAS down to 31kt!
At the other end of the speed scale I get the distinct impression that the Scout would probably exceed Vne in straight and level flight, but as there are a few bumps about we don't try. With Keith diligently taking notes, examining the cruise performance shows that 5,100rpm at 3,000ft produces a TAS of 96kt for a fuel flow of around sixteen lph.
This means that the range at 'fast cruise' is around 360nm with at least thirty minutes' fuel left. Reducing the power to 4,000rpm sees the fuel flow drop to only nine litres per hour. Fit the optional long range tanks and the endurance would be a buttock-bruising eleven hours!
Back at Little Snoring I discover that−as with almost every other aspect of flying the Scout−it's a very honest aircraft in the circuit, perhaps the single caveat being that pilots converting on to it from older, heavier, machines need to bear in mind that it has considerably less inertia than a Cessna 152 or Piper Tomahawk.
Indeed, for the first few hours it's probably prudent to stay away from full flap, because as soon as you close the throttle and flare the speed bleeds away at (both metaphorically and figuratively) a rate of knots! Fifty over the fence and it'll sit down where you want it, every time.
Having got comfortable landing on the long Runway 25 I finish off with a smooth three-pointer on the short bit of mown grass that parallels the taxiway. Great fun!
A second bite...
In late April Keith and I return to Little Snoring to shoot the air-to-airs, and it's a truly glorious morning.
Alpha Kilo is sitting on its very neat TLAC-designed trailer ready to go to the BMAA show at Popham, and I witness the wings being unfolded. As James had claimed, this is both a quick and simple process, and I'm pleased to note that all the controls remain connected, as advertised.
On my first flight I'd spent some time on the pre-takeoff checks, and the engine was warm as James had already flown the aircraft that morning. Today the engine's not been run, I'm quicker off the mark, the ambient temperature is lower and the engine seems slightly over-cooled, as it takes a while to get the oil above the mandatory 50°C.
I wonder if perhaps some sort of oil cooler flap might be worth fitting. TLAC are a famously proactive company, and I note with pleasure that the carb heat 'On' light is now a reassuring blue and not an alarming red, although I still think it's too bright.
Anyway, the oil eventually warms and it's worth the wait, for as soon as I've got 51°C I line up, open up and−wow! With only half fuel and no Keith I'm light, and the Scout is airborne almost before the throttle hits the stop and after a ridiculously short ground roll.
Off we go to the coast, where a combination of James flying a very smooth lead, a fine field of view, crisp controls, plenty of power, and the air over the water being as smooth as glass, lets me tuck in very tight. In fact, eventually Keith has to push me back a bit as at times the Cessna's shadow is right across the Scout.
Back at Little Snoring the wind has−as forecast−picked up, and Rwy 25 now has a fair crosswind, which combines with the trees directly upwind of the runway to produce some irritating curl-over on short final. However, it's nothing the Scout can't handle.
Conclusions? I feel that TLAC has got a winner here, and it's really pleasing to be able to write that sentence about a British-built machine!
Obviously care needs to be taken with the weight and balance of the ULA version, but with a typical useful load in excess of 235kg the VLA is a very practical machine, with good numbers for speed, range and endurance, and the ability to carry a good load into (and more importantly out of) even a pretty short strip.
The folding wings are a big plus, while the ability to reconfigure from a nosewheel to a tailwheel quickly and easily could also be very useful. I liked it. A lot.