A BMW with wings!

The sporty, Ger­man­made Aquila A211GX

Pilot - - FRONT PAGE - Words Dave Unwin Pho­tos Keith Wil­son

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, 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

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 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 snug­fit­ting cowl­ing, which fea­tures var­i­ous air in­takes and a large chin scoop, and also a small, slightly con­de­scend­ing ar­row to

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 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

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 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 over­speed­ing (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

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,

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

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. 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

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 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

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

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

Qual­ity, com­fort and per­for­mance

Over­all, 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.

4

5

7

6

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.