The Shark Jet is actually a high-performance sailplane derived from the Glasflugel 304 family, but fitted with a compact retractable jet engine and classed as a ‘self-sustaining’ glider, rather than a Self-Launching Motor Glider (SLMG in NPPL-speak) or a Touring Motor Glider (TMG on an EASA PPL).
This means that, although it could actually take off under its own power from a jet-length runway, the Shark is only certified as being capable of keeping itself in the air. Thus it can be flown by any glider pilot?and British glider pilots do not need licences, only a declaration of medical fitness.
The Czech-built Shark is a very modern sailplane, both in terms of aerodynamics and construction. Its turbine installation is probably the best thought-out available today, making this a thoroughly safe aeroplane with a very low cockpit workload, particularly suitable for the dyed-in-the-wool power pilot who doesn’t fancy the idea of every glider’s landing being dead-stick, and often into a field.
Sailplane aficionados will be familiar with the concept of the ‘turbo’, a small, low-capacity, usually two-stroke, piston engine and propeller unit, typically retracting into in the rear fuselage, and capable of helping a glider stay aloft when environmental lift is unavailable.
However piston turbos suffer from several disadvantages, among which can be slow extension, a profusion of uncooperative controls including microswitches, choke and decompressor, starting difficulties, the unit’s excessive drag if the engine won’t start, high in-flight noise and vibration, and the need to extend the thing and commence the starting process at least 1,000 feet above ground to be sure of eventual success?not to mention the fiddle of its cooling down procedure and propeller brake, plus the need to get its propeller precisely positioned before retraction.
The Shark’s jet engine extends quickly at the flick of a switch. Selecting a second switch (which can be done simultaneously) initiates start-up the moment it is locked in place. A mere thirteen seconds from deciding to use it, and after a height loss of little more than 100 feet, the Shark’s pilot has a turning, burning jet to arrest his descent – it flies level at idle rpm. Within a few more seconds full thrust is available with a twist of its panel-mounted rotary ‘volume knob’, giving it a climb rate of from 300 to 500 feet per minute at 65kt, depending on weight.
This TBS 400N-J40P turbine was developed from a target drone engine, of which more than 600 are already in service, with a proper electric starter, unlike most competitors, which rely on propane gas starting, with all its inherent problems. With FADEC (Full Authority Digital Engine Control) a data-logger and an independent Air Data Computer, this jet develops 420 Newtons of thrust – enough to push the super-clean Shark through the air at up to 120 knots. A 33-litre fuselage fuel tank (plus two optional forty-litre wing tanks if required) gives a cruise consumption of 20 to 24 litres per hour at 5,000 feet, although, as with all jets, this increases to 37lph at full throttle and sea level.
In practice this means that, off a short aerotow, or even just a 1,000-foot winch launch (costing a mere £8) the Shark’s pilot can fire up and cruise-climb for more than 100 miles to find lift. Then, when it’s time to return, the jet only needs to power its Shark within forty miles of home, from where it can glide back to base. Even in its current, un-podded form, this little motor generates less drag than the extended mainwheel, so there is virtually no penalty in popping it out at low level ‘just in case’. With no tax on jet fuel, a current price around 88p per litre and the possibility of using ‘red’ diesel, this gives really cheap flying. And an integral pump sucks fuel straight from your Jerry can without mess or fuss.
The Shark’s airframe is a carbon/kevlar composite, resulting in the low empty weight of 280 kilograms with superior, deceleration-absorbing cockpit protection. A broad spectrum of pilot heights and weights from 70kg to 125kg can be accommodated, and up to 240 litres of water ballast can be carried. MTOW is 600kg, while the whole jet installation weighs just 12kg.
With a choice of three wing-spans: fifteen, eighteen or twenty metres, this demonstrator has the most popular intermediate eighteen-metre span. Its aerofoil is a modern HPH xn2 (a modification of the HQ10-16-42, optimised for minimal lift degradation with external contamination from bugs or water droplets), with a 16.4% root thickness tapering to 13.2% at the tips, under which there are small, faired supporting wheels. A 27.43 aspect ratio, drag-reducing blended winglets on both wings and tailplane (the result of many hours of meticulous wind-tunnel testing) and a careful wing-root treatment result in a 51.2 to 1 glide ratio at 68 knots with minimum sink of a mere 83 feet per minute at 36 knots.
The inboard flaps are easily manually selected into three downward or three reflex detents plus any intermediate position. When deflected downwards they act as flapperons, while out at the wings’ very tips, short curved trailing-edge spoilers are lifted by a rising aileron. This results in notably low adverse yaw in such a long-winged glider. Three-section airbrakes extend from the wing’s upper surface. Combined with landing flap, they endow a startling (but obviously variable) rate of descent.
To date, more than forty Sharks have been delivered including several in Britain, and the factory has increased production to two airframes per month – already there is a thirteen-month waiting list. EASA has been formulating new rules for jet gliders, but full type certification is expected before the end of the year, with currently only a small temporary Vne reduction from 151kt to 145kt. Furthermore, a two-seat version is about to go into production.
If you want to join the 21st Century Jet Set, all this can be yours for around £110,000 ready-to-fly, including VAT and a purpose-built trailer for storage and transportation. For more information see the British dealer at: www.hphuk.co.uk