Flight Test The Eagle Has Landed - irp … · Flight Test | Aquila A211GX electrically-operated...

Flight Test | Aquila A211GX

electrically-operated single-slotted flaps which have three positions: up, 17° for takeoff and 35° for landing. A neat idea is the coloured bars on the upper surface of the port flap, which provide visual confirmation that the selected position has been achieved.

The engine is hidden beneath a snug-fitting cowling, which features various air intakes and a large chin scoop, and also a small, slightly condescending arrow to

fibreglass and carbon fibre, with the fuselage and fin being made in two halves and bonded together.

The wing features a triple trapezoid planform, which is strongly reminiscent of Schemp-Hirth’s famous Discus sailplane and uses a modified Horstmann-Quast aerofoil that was especially designed for the Aquila by the German Aerospace Centre. The spar and all other load bearing structures are constructed from carbon

fibre reinforced composite, while the shell structure of the wing is of foam sandwich construction covered with GRP skins. The wingtips curve up into large, graceful winglets which carry LED position and strobe lights, and the fuel tank vents. Whether these winglets reduce the induced drag sufficiently to warrant their existence I don’t know, but they certainly look cool. Inboard of the long-span narrow-chord ailerons are large

and has real ‘ramp presence’. However, having flown a lot of aeroplanes built to the US Light Sport Aircraft specification over the last few years, I couldn’t help but think that it looked a little on the heavy side. Of course, I soon realised that this aircraft is built to JAR VLA specs, which limit the maximum all-up weight to 750kg, not 600.

Unsurprisingly, most of the aircraft is made out of composites−primarily

Orbiting above the small grass strip and noting that the windsock was indicating a healthy crosswind, I briefly questioned the wisdom of

trying to land on such a short runway in a relatively ‘hot’ aircraft, fitted with a laminar flow wing. This really was a time for good judgement, which only comes with experience−and a lot of that comes from bad judgement. Only one thing to do:

try it, but be prepared to go around if it doesn’t work out...

With the notable exception of the current Volkswagen scandal, the Germans have always enjoyed a reputation for fine engineering, and the gleaming Aquila A211GX in front of me seemed certain to cement that reputation still further. Standing over 2.4 metres tall, it’s quite a big machine for a modern two-seater, and has graceful, flowing lines. It looks good,

24 | Pilot December 2015 www.pilotweb.aero www.pilotweb.aero Pilot December 2015 | 25

...once again on these shores, in the form of a new model of the German VLA brought in by a new UK agent

Words Dave Unwin Photos Keith Wilson

The Eagle Has Landed...

brakes. All three wheels feature close fitting spats (the nosewheel’s seems almost disproportionately large) and I approve of the cut-outs in the mainwheel spats which allow the brake pads and tyre pressures to be checked. (A trend amongst some light aircraft manufacturers is to make these−in my opinion, important−checks almost impossible without removing the spat.) Another thing I approve of is that the wheels are all the same size−an important consideration for a flying school operator, as only one tube and tyre size needs to be held in the spares store.

The A211 was proving to possess some small but interesting facets, and down at the tail I spotted two more. Firstly−and somewhat unusually−the tailplane is integral with the fuselage and cannot be removed. The rudder also features a small tab on the trailing edge which looks as if it should be ground-adjustable, but isn’t. Pitch trim is adjusted electrically, but rather than using trim tabs, the control forces in pitch are changed by altering the preload of a pair of springs attached to the elevator pushrod. Both the rudder and elevator are horn-balanced.

A good-sized lockable door on the port side of the aircraft provides access to the baggage bay behind the seats, which is also accessible in flight. I was impressed with both its dimensions and load-carrying

show propeller rotation. The landing light is between the scoop and spinner. Removing the top half of the cowling is relatively straightforward, although the oil and coolant levels can be quickly checked via a small hatch in the top cowling, while the External Power Receptacle (EPU) is located on the starboard side of the lower cowling, below the battery. The firewall is interesting in that as well as using a traditional sheet of stainless steel, it also incorporates a fire-resistant ceramic fleece. In front of this hangs a 100hp Rotax 912S, whose choke and carb heat controls are so last century−but the test aircraft was built before the fuel-injected 912iS (standard fit now) was certified.

The fuel (120 litres, of which almost 115 is useable) is carried in two wing tanks. The engine is fitted with a specially designed exhaust which, along with its hydraulically controlled constant-speed propeller, is claimed to make the Aquila extremely quiet. The prop is a two-blade wood/composite hybrid made by MT.

The undercarriage looks pretty robust: the nosewheel is carried by a pivoting tubular steel strut mounted on the engine frame support, shock absorption being provided by a stack of four rubber ‘doughnuts’ in compression. The mainwheels are mounted on a pair of cantilever steel struts and are fitted with hydraulically actuated Berringer disc



1: neat panel arrangement makes good use of the large amount of space available, with room for additional instruments

2: features we appreciate: lever controls for throttle and propeller (‘START’ = takeoff!) with ergonomically shaped knobs that will not be confused.

3: disposition of ‘stand-by’ mechanical instruments and the dual Garmin display favours the former, the ASI being ideally located, just under the glareshield and close to PIC’s line of sight

4: nice seats — and with this design the straps won’t fall off your shoulders

5: baggage door mounted fuel level dipstick with content indication graphic

6: closely grouped mixture, heater and choke controls (UK market aircraft will have English labelling!)

7: one further very good design feature —a flap-shaped flap operating switch with position indicator lights that is easily reached from either seat

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For a look at the cruise I set the throttle to 25.7 inches of manifold pressure and the prop to 2,200rpm. This is 75% of MCP, and the IAS soon settles on 120kt for a TAS of 124 and a fuel flow of 21.3 lph. Pushing the power levers up to the MCP of 27 inches and 2,260rpm

increases the speed to 130 and the fuel burn to 26 lph, but this isn’t really a practical power setting. On the other hand, 55%MCP (24

inches and 1,900rpm) almost halves the fuel flow to only 15 lph, while the TAS is still over 100kt and the endurance far greater than I need. Range at 75%MCP is a comfortable 500nm, although if you’re not in a hurry and use 55%MCP this stretches to over 700. An excellent safety feature is that even at MCP the IAS is only at the ‘top of the green’ or Vno, and still 35kt below the 165kt Vne. I remove my headset briefly to assess the ambient cockpit noise and am astounded at just how quiet it is. The heater is also ferociously efficient, while the air vents are equally effective−it’s a very comfortable cockpit.

Slowing down to assess the low speed end of the flight envelope reveals that, as I’d expected, the Aquila really is

quite slippery, as it takes a while to reduce speed. Stalls−either flap up or down−

are very benign, with adequate

aerodynamic buffet as the stall is approached. With full flap, the wing finally quits flying at about 42kt, accompanied by a

very mild wing drop. I would like to try a departure stall, but as the cloud base has continued to drop during the flight I decide against it. The Aquila is not approved for intentional spinning (it is not allowed under JAR-VLA certification) so we also stay away from that particular corner of the flight envelope. However, I doubt that it would display any particularly nasty traits in that department−the rudder is of a

good size and has a generous arm through which to apply itself.

Moving on to the stick-free stability I note that laterally it is positive from

that it’ll be fun to put this to the test and try the A211 on the short strip where my Jodel D9 is based. So I put photographer Keith in the other seat and we hop over to Castle Bytham. The main NW-SE runway here is about 450 metres, so it’ll be a pretty interesting experiment to discover how well it performs.

Unsurprisingly the surface wind seems to be similar to Saltby’s, with the windsock showing a moderate breeze, blowing across the runway at almost 90°. With the airspeed nailed to sixty as we skim the downwind hedge, the Aquila sits down nicely, and only moderate braking gets it stopped easily. Keith then disembarks and I fly a series of touch-and-goes for his camera. These go so well that for the final, full-stop landing I don’t use the brakes at all, but just let the aircraft decelerate naturally and it coasts gently to a halt. So far so

splendid, but in the interests of fair and honest reporting I must admit that our departure is a little more fraught. The grass is both slightly long and a bit damp, and the addition of Keith’s not inconsiderable bulk and his camera

equipment definitely make the final takeoff a considerably more protracted affair. We get out OK, but it’s a good job we don’t also have to clear ICAO’s legendary fifty-foot obstacle. That might have provided a real thrill, but to put this in perspective we are pretty heavy,

the wind is unfavourable, the grass wet, and the runway is less than 450 metres.

After a swift climb up to 2,000ft, I continue my examination of the A211’s control and stability, commencing with several 360 degree turns and steep reversals. These reveal absolutely impeccable handling. With the sole exception of the rudder the controls are all actuated by push rods, consequently the Aquila certainly has a very crisp feel about it. Both control response and harmony are entirely satisfactory, while the superb field of view provided by the big bubble canopy really does make you feel as if you are flying a little fighter.

the Aquila settles momentarily and then rapidly accelerates. An interesting anomaly is that the prop is pitched very fine, so almost as soon as you’re airborne you get audio and visual warnings that the engine is over-speeding (although the Rotax produces

its 100 horses at the relatively high crankshaft speed of

5,800rpm, power is conveyed to the

prop via a 2.43:1

reduction gearbox. Consequently the tachometer display on the EMU shows prop, not engine speed).

I soon learn that the trick is to leave the throttle wide open and just gently tweak the prop lever back to keep the rpm at 5,400 until 1,000ft

AGL, and then ease the throttle back to ‘MCP’ (max continuous, and marked on the throttle quadrant). Straight away I feel very comfortable with the A211. The controls feel crisp and responsive, while the constant-speed prop certainly turns the horsepower into thrust efficiently.

How would it handle a short strip?After a quick check-out I certainly feel very confident in the Aquila, and as I always like to do as thorough an assessment as possible for Pilot, I find myself ruminating “what could I do with it to push the envelope slightly?”

Anyway, a frequent criticism aimed at aircraft like the Aquila is that such ‘plastic fantastics’ aren’t suitable for farm strips. Consequently it occurs to me

ability (40kg) and also the fact that tie-down rings are built into the floor, allowing you to strap stuff down. A handy fuel dipstick and tow-bar are also stowed here. Overall I thought the Aquila to be well designed and equally well made, with typically Teutonic build quality−possibly making it the Audi or BMW of the VLA world.

Access to the cockpit is over the trailing edge of the wing, and a useful step is provided just aft of the wing, on both sides. The very large, front-hinged canopy is supported by powerful, well-damped gas struts. It opens wide, allowing easy access to the cockpit, which is surprisingly spacious for a two-seat aircraft. The seats are extremely comfortable and not only adjust over a good range but also rise slightly when slid forward (as the seat tracks are inclined upwards towards the front). I also liked the four-point harness, which has the best possible combination (for a light sport trainer/tourer) of fixed lap straps and inertia reel shoulder straps. Other nice touches are the dedicated headset holders between the seats and the small map pockets built into both cockpit sidewalls.

Thus far I’d been very impressed by the A211, and this generally favourable assessment continued in the cockpit. The canopy has a big DV panel, the majority of the switches for the electrics are rockers (which are less prone to damage than toggle switches) the throttle and prop levers and the controls for the park brake, carb heat and cabin heat are different shapes and sizes, the flap selector is flap-shaped and the circuit breakers are easy to see and reach. Even the standby analogue instruments are arranged correctly!

However, regular readers will be aware of my enthusiasm for all things ergonomic and yes; there’s still room for improvement. A bit of colour to more clearly delineate the circuit breakers and also the carb heat, cabin heat and park brake knobs wouldn’t go amiss, and while I understand the logic behind having a single, three-position rocker switch for the pitch trim located just aft of the power levers (its lighter, cheaper and easier than putting a switch on each

stick), I’d still rather it was incorporated in the stick top. Two things I didn’t like were the locations of the pitch trim indicator and the Primary Flight Display (PFD). Pitch trim position is shown on a bar of LEDs, which is located next to the pitch trim rocker switch (and thus barely forward of the elbow line, and at waist height). It really should be on the instrument panel, next to the PFD. Finally, I’d like the primary flight display to be directly in front of the primary pilot! Just like the Bristell tested last month, for some reason the Garmin G500 is just slightly offset to the right. I don’t know why this is (there’s clearly enough room to shuffle it over to the left a bit) but I did find it slightly irritating.

Engine information is displayed on a neat MVP-50 EMU (engine monitoring unit) on the opposite side of the panel,

with a small annunciator panel, a Garmin GMA-350 audio panel, GTN-650 GPS and GTX-328 transponder in the centre. I’d not seen the ‘touchscreen’

GTN-650 before, but it is certainly a very powerful tool.

Taxying is delightfully simple, with a fine view over and either side of the nose. The nosewheel steering is precise and positive, and if a very tight turn is required differential braking reduces the turn radius considerably. The hydraulic toe brakes are powerful and progressive.

Lining up on Saltby’s tarmac runway 07 with two PoB and half fuel we are about 60kg below the 750 MAUW, while ambient conditions are +14°C (for a density altitude of about 450ftAMSL) and around 12kt of wind, more-or-less on the nose. Acceleration is excellent and I rotate at 50kt after a ground roll of about 200 metres and climb away at the Vy of 65kt with the VSI showing a solid 800fpm. Selecting the flaps up at 500ft



Steep turn reversals reveal absolutely impeccable handling... the Aquila certainly has a very crisp feel about it


1 From the spinner back, the attention to drag reduction is evident

2 Mainwheel spats are cut away to allow the brake pads to be checked readily

3 Unusually for a VLA, an auxilliary power socket is provided

4 Cowl hatch allows speedy oil and coolant level checks

5 Baggage compartment is big, takes up to 40kg of stuff, has an external door and is accessible in flight

6 Potentially a life saver should the canopy ever become obscured, direct-vision windows on both sides

inset: suitable fuel types and (very usefully) capacity are indicated on the lockable filler caps

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SPECIFICATION

AQUILA A211GX ¤148,000*

Empty weight 500kgMax AUW 750kgUseful load 250kgPower loading 10.05kg/kwWing loading 71.42kg/sq mFuel capacity 120 lit (114.8 useable)Baggage capacity 40kg

n WEIGHTS AND LOADINGS

Vne 165ktCruise 130ktStall 43ktClimb rate 750fpmTake off to 50ft 450mLand over 50ft 400m

n PERFORMANCE

Wingspan 10.30mLength 7.35mHeight 2.40mWing area 10.50sq m

n DIMENSIONS

Rotax 912S liquid-cooled flat four producing 100hp (74kW) at 5,800rpm and driving an MT two blade constant speed propeller

n ENGINE AND PROPELLER

AQUILA Aviation GmbH OT Schönhagen FlugplatzD-14959 Trebbin, GermanyTel: +49 33731 7070Fax: +49 33731 70711Email: [email protected]: www.aquila-aviation.de

n MANuFACTuRER

Aviator Service www.aviatorservice.com working with Kairos Aviation,Poole, Dorset, tel: 01202 805179,email: [email protected]

n SCANDINAvIA & uK AGENT

Base price of an Aquila A211GX is €148,000. Aircraft as tested: €170,000 (both prices ex VAT)

n *PRICE

The measured noise level is said to be eleven decibels below the already very stringent German limit

both confirm that it really was very quiet. Intrigued, I wander down to the departure end of the runway to find out for myself if the noise level really is as low as they claimed. The measured noise output is said to be eleven decibels below the already very stringent German limit, and as the Aquila soared past I simply had to agree−it really is remarkably quiet. In fact, it is so quiet that farmer John had barely noticed my circuit session, and

that’s a very powerful endorsement for it being farm-strip friendly.

Quality, comfort and performanceOverall, I was very impressed by the Aquila. Students will love the easy, predictable handling, instructors will like the fine field of view and private owners will relish the generous baggage area, large comfortable cockpit and excellent performance, plus the ability to fly over 500nm at 120kt while only burning 21 lph of mogas. However, all that comfort and performance does come at a price−and that price (see spec box opposite) is considerable! Earlier on I described the A211 as being a bit like an Audi or BMW with wings, and it’s priced accordingly−but then quality has never come cheap.

starboard and neutral from port, positive longitudinally and strongly positive directionally.

Back at Saltby things are pretty quiet, so I try a few more touch and goes on the tarmac runways of 02 and 07, and the grass R07, including one approach with plenty of sideslip. As the tarmac R07 is quite long and also into wind, I decide that for my last circuit I’ll try it flapless. To be honest, I’ve always been a little cynical

about using flap when taking off from a long tarmac runway in a small aircraft, but the A211’s laminar flow aerofoil genuinely needs flap for take off; the wing just doesn’t seem to want to fly without flap at 50kt and it’s only at sixty that it finally flies after a considerably longer ground roll. Less surprisingly the flapless landing is an even more protracted affair, and the A211 simply floats along the runway in ground effect while showing no inclination to land. Just when I’m starting to think that perhaps I ought to go around it slowly and reluctantly subsides onto the ground, but we do end up using most of the runway.

As the A211 is claimed to be an extremely quiet aircraft I ask a couple of the club members about their perceptions while I was bashing the circuit, and they

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