X-Air

Keep it in a shed on a farm field or paddock (and it certainly does not have to be a big one, nor possess uncluttered approaches) and you can get all the flying enjoyment you want, and with far more freedom, for a mere fraction of the cost of hiring a club aeroplane.

Getting into the X-Air is the only difficult part; after that, everything’s instinctive. The (optional) upward opening doors are flexible Lexan, framed with lightweight aluminium tubing, and opened by twisting them gently off their location pegs. Short stays, held in place by Velcro, prop them open; rubber handles keep them closed. The trickiness of entry is because a pair of struts and a spatted wheel obscure bottom dead centre of each doorway. I achieved access from both ahead of the struts and behind them, but neither was very gainly.

Once ensconced, there is plenty of length and width (the makers say 55 inches or 140 cm) for two, with comfortable floor level seats and comprehensive harnesses, good all round vision and quite enough instruments for this sort of flying. Start up requires full choke (on an overhead structural tube) and plenty of battery charge, but given those, the Rotax bursts into instant life. Since it was designed with less experienced pilots in mind, the X-Air’s panel is well endowed with appropriate placards. One says: Best idle 2800 rpm and it’s correct. Below that the Rotax gearbox chunters uncomfortably.

Taxying is similarly simple, with effective differential toe brakes and good, direct nosewheel steering. The aeroplane can be turned in its own length, making light of even the trickiest obstacle courses. Again, there is a checklist right in front of you on the panel, but in truth with no flaps or other complexities, there’s little to do pre take off once the engine’s running.

The take off itself is pretty darned quick, too. I had barely got the throttle fully open before we were in the air, this little springbok leaping off the turf in well under a hundred metres. I just had time to spot our lift off speed at 35 knots. The panel placard says: take off 70m and I believe it, although Jane’s quotes 220 metres to clear fifty feet (fifteen metres) height. Climbing at a very conservative 55 knots to be super-safe in this super light and slightly draggy airframe, I was unable to get the stopwatch in my new phone to cooperate, so I counted the seconds, timing the climb at 750 or more feet per minute. And this low airspeed makes for a spectacularly steep climb angle.

Continuing on up to 3,000 feet, I monitored the engine temperatures, which all stayed well within their limits (also all placarded, with the stickers sensibly sited right beside the appropriate dials). At first this slightly flexible airframe seemed a mite flimsy (and I had excited a sinusoidal wave along the wings by waggling up and down on one tip during my pre flight inspection), but then I realised it was my perception rather than a true lack of structural strength, for this airframe exceeds the rigorous requirements of the British CAA’s BCAR Section S. Anyway, had I not also marvelled at a Boeing 747 wing’s flexibility when waggling its tip up and down at Everett?

The X-Air’s primary structure is aluminium tubing held together with steel bolts, and critical joints are bushed or sleeved. The Dacron fabric covering is held in place by Velcro, making it much easier to remove and replace or repair than on a more conventional airframe. Wing surfaces are virtually double skinned, with wide span ailerons outboard, but no flaps. All the tail surfaces are similar, and all controls are cable operated. With an empty weight of around 250 kilogrammes, the 450 kilo maximum weight limit allows a realistic payload of full fuel plus two 80 kg adults.

The engine is a 48 horsepower, water cooled Rotax 582, twin cylinder two stroke, and generally regarded as more reliable than the two stroke engines from some other manufacturers. Nevertheless, these Rotaxes do have their idiosyncrasies. A particular problem for these (and Jabiru) engines is battery capacity. Without sufficient charge, while the propeller will turn over, the starter just will not spin the engine quickly enough to generate a spark. You can spend months trying to fix an apparent carburettor or ignition problem, when all you need do is spend a few bucks on a new battery.

Reaching 3,000 feet in a little over four minutes, I left the throttle wide open to see what speed could be achieved, and the ASI slowly crept up to 68 knots (70 knots TAS) at a rather buzzy 6,300 rpm. Vne is 80 knots, so this gave us a comfortable margin. Reducing power to the recommended maximum cruise setting of 6,000 rpm brought the ASI back to 63 knots, or 65 knots TAS. That is 75 mph, and precisely as advertised. Throttling back further to 5,000 rpm brought our speed down to a mere 43 knots, ideal for loitering, sightseeing and circling, and yet still with a comfortable 50 per cent margin over the power on stall speed.

All these speeds could easily be trimmed out using the trim lever by my right elbow. This operates a small tab on the left elevator. There is no trim in the other axes, nor is it needed. Fuel consumption should be around 13 to 15 litres per hour, giving at least three hours safe endurance, and Raj Hamsa quote a 165 nm still air range. Fuel capacity is marked by felt pen lines on the semi transparent linked twin 27 litre tanks behind the seats, as well as being indicated on the panel gauges.

“Reaching 3000ft in a little over four minutes, I left the throttle wide open to see what speed could be achieved, and the ASI slowly crept up to 68kt.”

The X-Air’s controls surprised me, for they exhibited none of the dainty skittishness one might expect from such a lightweight aeroplane. They operated more like a bigger, heavier aircraft’s; quite an effort being required to manoeuvre at its higher speeds. Nevertheless, the roll rate was comfortably similar to a production American airplane’s, it taking two seconds to roll from 45 degrees of bank one way to the other at 55 knots, and despite the ailerons’ differential, a squeeze of rudder was always required to coordinate turns, which is as it should be. All three axes required similar effort, so the harmony was fine, and stability was strongly positive in all axes. Indeed, I was able to let the X-Air fly along happily for ages while writing my notes.

Downward visibility is peerless, as it also is all around the horizon, particularly ahead over that tiny nose. Twirling round and round at fifty knots enabled close and continuous inspection of everything below us. My only criticism is that this airframe configuration inevitably blanks off the view overhead, and thus, into turns too. Indeed, when you close the throttle and lower the nose to dive at 70 knots, you almost (but not quite) lose sight of the horizon up ahead behind the leading edge. I needed a little right rudder to counteract the yaw caused by that power reduction, although at no time did I notice much need for any left rudder with high power settings, so presumably there is some in built fin offset.

Slowing for a stall, and as you would expect from its NACA 4412 aerofoil, I could barely perceive a little, very light buffet one to two knots before the G break, but this might not be noticed at all if a stall was induced inadvertently. There is no artificial stall warning, but the controls become so light, the nose is raised so high, and the stalling airspeed is so incredibly low at 27 knots, that I doubt it would happen by mistake. Also, recovery was immediate upon relaxation of the back pressure. Very few aircraft fly so slowly, making this a particularly safe aeroplane, and its predecessor the Weedhopper claimed a mere ten foot height loss during stall recovery.

Gliding back to the circuit at 45 knots, I was surprised by the distance we covered relative to our height lost. This rather draggy airframe is certainly no sailplane, but it went further than I had anticipated. Should a steeper descent be needed, sideslipping worked well, even right up to full rudder deflection, which appeared to double our descent angle.

Like most aircraft, it wasn’t brilliantly responsive power off, but still more than adequately controllable in all axes. During this descent, I did discover one tiny annoyance. Every time I reached out my right hand, to tap a gauge perhaps, or maybe to change radio frequency, I knocked the right throttle lever with my elbow. There are two levers, one to the left of each pilot’s seat, and they are remarkably long, maybe eighteen inches (forty centimetres) high. They move through as much as a foot (thirty centimetres) of travel, and operate the throttle by pushing on a Bowden cable’s outer sheath rather than conventionally pulling on its inner cable. Although this example had an inch (2.54 millimetres) of slack in its cable, and therefore three inches (about eight centimetres) of lost motion in the lever’s travel, they surely do not need to be anything like so long.

Initially being wary of the X-Air’s low inertia, I made my first approach at 55 knots, but soon realised that was far too fast, and caused an unnecessarily long float, so I progressively reduced the speed to fifty, and then back to 45 knots. Even then, we still floated, but not so far until, finally crossing the threshold at forty knots I eventually achieved a sensibly short landing. And even at our crawling pace thirty knot touchdown speed, there was still plenty of elevator to get a proper nose high touchdown, although you do have to bring the control column back quite quickly because of the rapid, drag induced speed reduction. Pushing off the drift caused by a ten-knot crosswind was not an issue either, there seemed to be plenty of rudder, probably enough for an even higher crosswind.

The main undercarriage suspension comes from a Royal Enfield motorbike, assuring a gentle touchdown every time, with no bounces, and it is tough and strong enough to absorb the punishment of novices. Once properly on the ground, and with the nosewheel lowered, I was able to apply quite heavy braking and stop in well under 100 metres. Alternatively, opening the throttle caused a wallaby like bounce back into the air at forty knots and straight into an enthusiastic fifty knot climb.

Flying my new found Flexible Friend round and round the circuit of a deserted country airfield on a summer’s evening, banking and turning, gliding and sideslipping, while the sun waned towards the far horizon, bathing the lush green foliage below in golden light, I was reminded of nothing so much as sailing a dinghy on a tree lined river. You don’t use a dinghy to go places – not seriously; but you can have the most tremendous fun sailing back and forth, tacking and gybing, reaching and running, going nowhere in particular with one hand resting lightly on its tiller, a sheet in the other, and your eyes on the wind in its sails. Neither is particularly practical, but both are wonderfully relaxing.

To wickedly paraphrase Kenneth Grahame’s Toad, “Believe me, my young friend, there is nothing – absolutely nothing – half so much worth doing as simply messing about in ultralights”.

ENDS
© R J Grimstead 2008

Sidebar 1: The X-Air’s background

The X-Air (also known as the X’Air) is an Indian design, originally developed in 1993 from American John Chotia’s 1970s immensely popular Weedhopper, and subsequently certified under the CAA’s stringent BCAR Section S. The production company, Raj Hamsa Ultralights, also sells five models of hang-gliders and powered hang-gliders.

The baseline X-Air 502T has a fifty-horsepower Rotax 503 engine. The featured model X-Air 602T uses a 58hp, 580cc, two-stroke Rotax 582. Next comes the X-Air 604T, with a sixty-horse HKS 700E motor, while the top-of-the-line X-Air 702T uses a 70hp AMW 540L70 engine. Other than engine size, these airframes are identical.

A later development is the rather more conventional-looking Hanuman or X-Air Hawk, which uses either the same Rotax 582 as in the featured aircraft, or a four-cylinder, four-stroke Jabiru 2200 engine.

Designed in France and built in India, the homebuilt X-Air has a claimed mere 100-hour assembly time, simply by following the instructions on a DVD supplied with the kit. Builders are exhorted to: ‘just add engine, instruments and propeller’.

The design boasts a roomy, 55-inch wide cockpit with comfortable seats, dual controls, differential toe (drum) brakes, elevator trim, proper suspension (the main gear uses the rear springs and bounce-damping shock-absorbers from Indian-built Royal Enfield motorcycles), 57-litre (three hour plus) fuel tank, and the resulting airframe is said to be stressed to +6/-3g. Cruise speed is a sightseeing rather than blistering 65 knots, with an ultra-safe 23-knot stall. More than 1,300 X-Airs have now been sold.

Cost of a new airframe kit, as quoted on the X-Air Australia web site is a mere $14,999. Manufacturer: Raj Hamsa Ultralights Pvt Ltd, 40 Goshala Road, Mahadevapura, Bangalore 560 048, Indiah. https://x-air.in/ Aussie dealer: Michael Coates of X-Air Australia: 07 5568 7770 or www.mcp.com.au or [email protected]

Sidebar 2: An owner’s impressions

Ed Smith, former school principal, but more recently a flying instructor and aircraft dealer, owned this example for three years, during which time he claims colourfully, ‘Apart from fuel, it didn’t cost me a brass razoo!’

How much did you pay? ‘With all its options, including radio, intercom, extra instruments, doors and wheel fairings I paid a little over £10,000.’

What did he use it for?

‘Well, I learned to fly in it and then had a lot of fun in it afterwards. Most of the time I drifted around at about 45-50 knots, simply enjoying myself, although I did do a couple of 200 nm runs in it. At lower speeds, it only used about 9 litres per hour. For the sheer fun of flying, it was hard to beat. Even after I bought a Jabiru I still used to get out the X-Air on those lovely calm evenings when it is just pure fun to fly. Its most practical cruise speed is sixty knots, and 300 metres of level paddock is quite adequate for taking off or landing. Much less if you work hard at it.’
‘A couple of interesting things I did with the X-Air I still remember well. One day I was overflying a farmer friend’s house when he heard the unmistakable sound of the two-stroke and came out to wave at me with what was obviously an invitation to come in for afternoon tea. I landed on his back lawn and taxied up to the kitchen door. “Pretty good but how do you plan to get off again?” Tea and scones finished, I revved her up, best short field technique, and showed him just how versatile that little plane was.’
‘I also flew her backwards across a large part of Princess Royal Harbour on a day when there was forty knots of wind up at 3,000 feet. Settled her down to around thirty indicated and drifted backwards. Great fun and totally mystifying for the fisherman in the dinghy below who was keeping pace with me, only he was going forward of course.’

Were there any problems?
‘I was always very fussy with maintenance. I made a point of pulling the plugs every 25 hours, they were generally quite ok but I did that anyway. I used only the best two-stroke oil, at the time TS40C, which is no longer available. At 50-hour intervals I removed the exhausts and inspected the piston crowns. They stayed remarkably clean and the rings were always free in the piston grooves, no signs of fouling ever. I flew around 200 hours in the X-Air with no problems of any kind apart from once, when I picked up some fuel contaminated with Claudisporum Resinae bugs. That gunk blocked up the fuel filter and I had to make an uneventful forced landing in a paddock. But I cleaned out the fuel system, refuelled and flew out again later that day.’