Flight Test: Aeroprakt A-22 Foxbat
12:53 13 October 2016
KEITH WILSON SINGLE USE PILOT MAG ONLY
The factory-built version of the Yakovlev-designed ultralight, available in improved form in the UK as a microlight- or ‘Group A’ kitplane, really is the Fantastic Mr Foxbat
Words: Dave Unwin; Photos: Keith Wilson
“How’d you like to fly a Foxbat” asked photographer Keith. But just as visions of the fabulous Mach 2-plus Soviet fighter flashed into my mind, he added: “That’ll be an A-22, not a MiG -25”.
Known as the Valor in the US, the Foxbat in Australia and Britain, and the Sharik in the Ukraine – where it was designed – the A-22 is a very capable if unconventional looking machine. Designed by Yuri Yakovlev in the mid-1990s, it is built by Aeroprakt (which translates as ‘practical aero’) of Kiev, with the prototype making its maiden flight in 1996.
The test aircraft, the L2 variant, is s/n 449 and was factory built in 2014 – for the UK market, only kits are available. It is owned by young Lithuanian entrepreneur Vytautas Kiminius and his father, who have put around 200 hours on it, although it still looks like new.
I’d flown an A-22-LS (the Light Sport version) on amphibious floats, called the Cape Town, way back in the noughties, and had briefly sampled a Valor while on assignment in the US. However, even from a distance I could see that LY-UCB looked different from either of those two aircraft, with the most obvious being it isn’t quite so extensively glazed. The nosewheel strut also looked slightly different.
My initial impression was it appeared to offer excellent visibility, as liberal use of Polycarbonate has replaced many of the fuselage and door panels, and the doors actually bulge outwards. Closer inspection revealed the A-22 to be intelligently designed and well made to a high standard. The wing mounting points have self-aligning spherical bushes fitted, and where a bolt is used as a pivot there is always a spherical bush or bronze insert fitted to minimise friction and wear.
You can guess what the engine is – the practically omnipresent Rotax 912. UCB is powered by a 100hp 912ULS (with the fuel-injected iS as an option), which spins a three-blade carbon-fibre ground-adjustable Kiev prop. The cowling features a front opening so big that, at first glance, I wondered if the engine was an air-cooled Jabiru. The oil cooler and radiator are both quite large, and I wasn’t surprised to see part of the oil cooler is covered by duct tape. Vytautas confirmed it is slightly over-cooled, and he has fitted a thermostat as well as covering the oil cooler.
Access to the engine bay is good. The composite cowling splits horizontally, with the top half secured by four Camlock fasteners, while the bottom is attached to the airframe with screws.
I would like a small hatch to just dip the oil through, but removing the entire top half does at least mean you get to perform a more comprehensive pre-flight inspection.
The top-half of the cowling features an optional small scoop (more of a half-dome really), which functions as a ram-air intake for the induction system, while there’s an LED landing light in the bottom.
The undercarriage is an extremely rugged looking affair, conventional in both design and construction. The nosewheel is suspended from a hinged strut with shock absorption provided by a coiled steel spring and gas strut, while the mainwheels are carried by aluminium legs and fitted with large hydraulic disc brakes. All three wheels use the same size wheels and are fitted with massive, optional 600 x 6 Tundra tyres (500 x 6 is standard). I particularly liked the elegantly simple mudguards.
Along with the cowling, composites are used for the chamfered wingtips, with the fuselage being of mostly metal construction (riveted anodised aluminium), while the wings feature a metal leading edge, stamped aluminium ribs and fabric covering aft of the D-box. Unlike many ULA/LSA-type aircraft, the rivets are mostly solid and not of the blind or ‘pop’ type.
The strut-braced wings look quite unsophisticated (they are constant-chord, as is the tailplane) but on closer inspection, there are some innovative elements. Firstly, they are slightly swept forward (only 2°), while the trailing edges are covered by full-span fabric covered ‘flaperons’. These have three settings ‘up’, 10° and 20°, and are actuated by pushrods and torque tubes. During the pre-flight briefing Vytautas emphasised it has an impressively low stall speed, and looking at the large flaperons I can clearly see why.
There’s also a sizeable slot between the trailing edge of the wing and the leading edge of flaperon, and I wondered if this allows the flaperons to function as a sort of ‘Fowler’ flap when they are drooped. The aerofoil is a high-lift section, and is unusual in that it is quite deep with a slightly cambered under-surface. (I subsequently read it was developed by the famous Russian designer Oleg Antonov in the mid-1940s, for a Red Army observation aircraft).
All the fuel is carried in a pair of tanks located in the centre of each wing, near the wing roots. These have a combined capacity of 90 litres, of which 89 are useable. The top of the tanks actually form part of the upper surface of the wing and can be easily removed for maintenance.
Despite having wing tanks, as the A-22 was originally designed with folding wings (now discontinued, due to the weight penalty), it can be de-rigged quite easily as the flaperons and fuel lines are connected with quick-release fittings.
Moving towards the tail I noticed that, unlike the two A-22s I flew in the States, this one is not so extensively glazed aft of the doors, and I have to say I prefer it. It somehow gives it a more substantial appearance, making it look more like a small aeroplane and less like a microlight (which, with a MAUW of 472.5kg it is, of course).
There’s a small frangible panel just aft of the wings for the BRS to fire through. At the base of the ventral fin is a glider tow-hook. If a tow-hook isn’t fitted then a small, fourth wheel is. Apparently the combination of an authoritative elevator, good power-to-weight ratio and a CG close to the mainwheels makes a tail-strike a bit too easy during the take off ground roll.
The tail unit consists of a big, slightly sweptback fin and small ventral fin, large rudder and single-piece elevator. It is designed and constructed along the same lines as the wings, with the fin and rudder made from stamped aluminium ribs covered with anodised aluminium sheets and Ceconite covering the pushrod-driven elevator and cable operated rudder. Pitch trim is provided by a cable-driven tab on the port side of the single-piece elevator. There are also ground-adjustable trim tabs on the rudder and starboard flaperon.
Cockpit access is excellent, as the sills are nice and low while the large gull wing doors open wide and are firmly supported by well-damped gas struts. However, the large pitot is extraordinarily badly sited on the port wing strut, and is just asking to be walked into. The only way it could be any worse would be if it was on the passenger side, and I urged Vytautas to paint some red & white stripes on it.
An excellent feature is that A-22 is approved for flight with the doors off so they can be easily removed. The seats can be adjusted fore-and-aft and for rake before getting in. Once strapped down with the four-point harness, I swung the big door closed and began to appreciate just hwo remarkably spacious the cabin is.
As mentioned earlier, the door panels are bulged outwards, and this means that at its widest point the A-22 is an astonishing 132cm wide!
This is actually greater than many ‘legacy’ four-seat GA aircraft (the maximum width of Cessna 172’s cockpit is only 100cm). The spacious sensation is enhanced by the transparent door panels. Continuing my examination of the cockpit, I found many features I approved of, and a few I didn’t. I liked the well-placed headset holders (above and behind your head) and the fact the sockets for the jack plugs are located nearby. Not only does this keep the cockpit tidy, but keeps the headset’s leads away from the controls.
However, I didn’t like the dual fuel valves, which are also above and behind the pilot’s heads, one on each side. Important controls like that should be in front of you, easy to both see and reach. To be fair, you can just leave both on, but I’d like to see a single fuel shut-off selector (maybe a guarded knob similar to the Robin 200) mounted either in the panel or centre console.
The panel features a large centrally mounted MGL MFD (multi-function display) plus analogue metric ASI, VSI and altimeter, compass and slip ball and a neat little MGL radio. A small sub-panel extends down from the base of the instrument panel and carries dual fuel gauges, a row of toggle switches for the electrical services and a separate pair of guarded ones for the mags, combined rotary master/starter switches and a fuse box.
Extending aft between the seats is a centre console containing levers for the parking brake, trim and choke, with the throttle and brake further back and a T-handle for the BRS behind the throttle. There’s a wheel-type friction-lock for the trim on the console’s side.
Behind the seats is a large baggage bay, which can hold up to 20kg. As the seats, fuel tanks and baggage bay are all concentrated around the CG I would imagine balance issues are unlikely to be a problem - an excellent safety feature.
The robust-looking rudder pedals are hinged to the floor. They operate the rudder by cables and the nosewheel via pushrods. Up in the roof is the flaperon lever – to lower the flaperons, you move it sideways to unlock it, and then pull it to the desired setting. Overall, I judge the cockpit to have an intriguing mix of good and bad features.
I don’t like the location of the fuel valves, but like how a light flashes in the relevant fuel gauge when the fuel in that tank is getting low. The location of the trim lever is good, but the lack of any sort of position indicator isn’t. And somewhat confusingly, the throttle and choke levers are black, but the brake, parking brake and trim levers are brown (the trim really should be green, particularly as the tow hook installation means gliding club pilots may fly it, while the brake levers might be better blue).
The co-located plungers for the carb heat and cabin heat are far too samey – almost identical, in fact – but the control lock, often omitted in light aircraft, is great.
But the two features I really take a dim view of are the master switch and tow hook release. The master is one of those ghastly key-operated rotary units, which really is an extraordinarily bad idea. The first setting turns the electrics on – turn it further to the right and it cranks the engine. This is an accident waiting to happen, particularly if a nervous student pilot was a bit ham-fisted. Finally, the tow-hook release is in the roof, adjacent to the flap lever. This is terrible as it really needs to be adjacent to the throttle.
Let’s go flying
With the Rotax idling away with its characteristic muted whine and Vytautas in the other seat I released the parking brake. It’s only a brief taxi from the apron to Conington’s runway 28, so I didn’t get much of a chance to evaluate the ride quality. It did feel quite firm, though, and the nosewheel steering seemed precise and nicely weighted. I couldn’t help but think taxiing in a strong crosswind could be a bit trickier as the A-22 does not enjoy the benefit of differential braking, although the brakes themselves are really quite powerful.
With an OAT of +3°C and an elevation of only 36ft, density altitude is clearly not an issue (it is actually about 1500ft below sea level) although frostbite or hyperthermia for Keith might be. With forty litres of fuel, Vytautas and I are quite close to the MAUW (the LSA/ ‘Group A’ version has a 600kg MAUW, with the only real difference in construction being that some parts of the wing are covered with aluminium, not fabric). Vytautas is quite a big bloke and I’m not getting any thinner, yet we’re not touching shoulders.
Acceleration is excellent and I experience no difficulty in keeping straight. The take off is impressively brief and I soon see why there’s a tailwheel fitted if the tow hook isn’t. The elevator is powerful, and a clumsy student could easily cause a tailstrike.
Climbing out at 55kt and just under 900ft/min, my initial impression is that the field of view really is very good. The steeply raked windscreen and bulged Perpex doors give it an airy feel, but they might almost make it a little too exposed for some passengers. I’d be minded to paint a horizontal black line at about waist level.
As I moved into position on the Flying Club Conington C152 carrying Keith, I become aware that although the A-22 has crisp, powerful controls, the throttle is rather stiff for close formation work, and it takes me a couple of minutes to get comfortable with it. Apart from this, it’s an easy aircraft to fly formation in, which is just as well as Keith is working in temperatures that (with the wind chill generated by our 70kt cruise speed) are probably somewhere around -21°C!
Photography session complete, we waved goodbye to the 152 and I begin to evaluate the control and stability. An examination of its general handling reveals forceful flaperons, an effective elevator and a powerful rudder. Breakout forces are low and control harmony mostly good, although the rudder is perhaps a little light and the flaperons a touch heavy. The rate of roll is perfectly adequate, while the field of view in every phase of flight is excellent.
An examination of the stick-free stability produces some curious anomalies. I’d expected it to be strongly positive longitudinally, but pitching up for a ten-knot displacement from a trimmed speed of 75kt and then releasing the yoke sees it slowly pitch down through the trimmed attitude and then just keep accelerating, which I find most peculiar.
Lateral stability is essentially neutral but directional stability is also - somewhat surprisingly - negative. As the fin is quite big and works through a reasonably long arm, the moment should be adequate, and I wonder if perhaps it’s a combination of the rudder not self-centring (as it is not fitted with springs) and the not-inconsiderable side area of the nosewheel’s Tundra tyre being in front of the centre of pressure.
A look at slow speed flight is noteworthy, and as I’ve found with many LSA-type machines, the speed at which an unaccelerated 1g stall occurs is difficult to determine accurately as the ASI is imprecise, due to position error. The POH claims with the flaperons drooped to 20° and the throttle at idle, the A-22 stalls at about 28kt. I have no reason to dispute this claim.
The pre-stall buffet is mild but the ridiculously steep pitch angle is a strong cue that perhaps not everything is as it should be!
Another anomaly is that when stalled with the flaperons fully retracted, the yoke ‘snatches’ quite vigorously to port at the actual stall, and with them extended to either 10° or 20°, it snatches just as abruptly, but to starboard. Note that the aircraft doesn’t really roll, but the yoke definitely moves. Probably the best way to describe it is that it almost feels like a ‘stick-pusher’, but for the ailerons. In fairness, I do like to hold the yoke lightly, but nevertheless at the point of stall the yoke is undeniably wrenched quite forcefully out of my hand.
Standard stall recovery is quick and easy, with little loss of altitude. If held in the stall with the yoke on the backstop and ailerons neutral, it simply sinks straight ahead in a stable condition and a vertical speed of less than 500ft/min. You could ride it right down to the ground like this, and although you might burst the tyres you would definitely walk away.
This is a very safe aeroplane. When stalled in the turn (and with a firm grip on the yoke) it rolls wings level - an excellent trait. Gentle 90° turns just above the stall reveal the flaperons work well even at such slow speeds, while pulling the throttle right back and trimming for 55kt demonstrates the glide angle is agreeable flat.
Safe on soft surfaces
Gazing down at the semi-flooded fields of the Cambridgeshire Fens, I was glad our Foxbat had Tundra tyres. In the unlikely event of an engine failure we would still be able to safely land on the sodden surface, but most nosedraggers definitely wouldn’t.
Cruising back to Conington discloses the somewhat boxy A-22 is actually faster than it looks. A high cruise speed of 97kt is perfectly achievable, and sustainable, albeit rather noisy and thirsty. Around 85 is a more practical speed.
The seats are extremely comfortable. Vytautas made some new squabs out of memory foam and when he and his father flew the Foxbat 1,000nm from Lithuania to Conington, they definitely proved their worth.
Circuits are great fun; the field of view is excellent and the combination of lots of drag and plenty of power make accurate touch-and-goes easy. Keith has positioned himself just in from the threshold and I do my best to roll the wheels ‘on the numbers’. As I’d suspected while taxying out, the Tundra tyres give a fairly rigid ride and although I did my best every touchdown seemed somewhat firm.
About 55kt on final works well, bleeding the speed back to about 45 ‘over the fence’. The POH claims a take off or landing ground roll of only 100m at MAUW, and I can well believe it.
Even landing over a 50ft obstacle requires less than 250m, and along with the big Tundra tyres make the Foxbat a fine farm strip flyer, while the 90kt cruise speed, comfortable cockpit, long range and reasonable baggage allowance make it an excellent tourer. Care does need to be taken not to exceed the MAUW when flown as a microlight (the LSA version has an extra 128kg of useful load) but apart from that the Foxbat really is an admirable little aircraft.
Wing area: 12.62m2
WEIGHTS AND LOADINGS
Max AUW: 472.5kg
Useful load: 201.5kg
Power loading: 6.3kg/kw
Wing loading: 37kg/m2
Fuel capacity: 90lit
Baggage capacity: 20kg
Climb rate: 690ft/min
Service ceiling: 16,000ft
ENGINE AND PROPELLER
Rotax 912s liquid-cooled flat-four, producing 100hp (74.57kw) at 5,800rpm driving a Kiev three-blade ground-adjustable propeller
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