Up'n stable: after a somewhat hesitant debut, the unmanned vertical take-off and landing aircraft now appears to have come of age. This is for a major part due to innovative techniques, miniaturized autopilots and navigation suites as well as restored credibility amongst potential users.

All of a sudden, the engine crackled to life k and after a short warm-up the typical chatter of helicopter blades biting into the air cut in and the white bird cleanly broke contact with the grass field of the Austrian countryside. It resolutely soared, soared and soared and then steadily remained in a hover flight as if held by an invisible, but firm, hand in the sky--hardly any 'wobbling', or involuntary rolling and pitching throughout the sequence. The S-100 then transitioned to forward flight, turned right to cross the author's field of view, cleanly turned right again and flew away into the distance only to return minutes later to perform a long hover before smoothly landing in full automatic mode simulating datalink failure (the pictures of the event taken by the author involve the experimental aircraft which carries various back-up aerials and sensors that will not appear on a production model).

The first feature that characterizes the sleek S-100 is its stability, in spite of small wind gusts during this demonstration staged by Schiebel not far from Vienna. This is not Schiebel's first inroad on the helicopter drone scene as the Austrian firm--originally, and still, a landmine-detection specialist of high international repute--had earlier developed and produced a short series of smaller Campcopters, the 5.1. The Camcopter S-100, which was first featured in Armada 2/2005, is an entirely different breed though, as it uses a monocoque carbon-composite airframe with integral fuel tanks. In other words, all ribbings and double skins are one single piece. Mechanically, the engine is basically a Sachs rotary piston block that has been highly modified to incorporate a home-built fuel injection system and a double power generator. Likewise, the redundant autopilot, trebled flight control computers and ground-based computer are also proprietary developments. Normal maintenance is scheduled at 250-flight-hour intervals although a routine change of spark plugs is recommended at every 50 flight hours, while the gearbox is a 10,000-hour no-maintenance affair.

In designing the S-100 Schiebel's aim was to offer the same performance as a fixed-wing drone of the same payload category. It can thus fly at 120 knots, stay aloft for six hours and has a 150 km omni-directional datalink range at an above-ground height of 9000 ft. The chopper is designed to fly back home and land automatically (which it did during the demonstration, as said above). Both the main and tail rotor hubs are machined from forged titanium blanks and the blades are, of course, all composite. Schiebel's S-100 can be operated in winds of up to 20 knots, but given its stability, the firm hopes to be able to extend the limitation up to 30 knots.

The S-100 launch customer is the United Arab Emirates (for which production started in June with deliveries slated to commence in December 2005). Asked if there were other export orders, Hans Schiebel answered quite laconically, <<quite a few>>.

In the lower-weight category but still within the whirly birds, we also now have the Bertin Hovereye, which was unveiled at the Paris Air Show in June. This is more extensively described in our Complete Guide to Urban Warfare despatched as a supplement to this issue.

At the opposite weight end is another novelty that could soon come to fruition under the joint auspices of Eurocopter and Guimbal, who have formed a new company called Vertivision with a view to responding to a French Navy request for proposals. Like the Northrop Grumman Fire Scout, its underpinnings belong to a 'real' helicopter, the Cabri in this instance. Other members of the team include Eads for the payload and ground station. The yet-to-be-named machine (as an earlier project it was known as the Orca) is to have a take-off weight of about 700 kilos with a payload of 150, a speed of 100 knots and an endurance of eight hours. Presently the Cabri is powered by a Lycoming engine, but the current plot is to give the unmanned version a 1.7-litre diesel set of pistons borrowed from the Mercedes A Class automobile. If selected by the French procurement agency, a first prototype could be flying by the end of 2006.

Incidentally, Bell, teamed with Sagem, is eyeing the same French Navy programme, for which it is proposing the tilt-rotor Eagle Eye.

Fixed Wing Affairs

Back to the fixed-wing category, the breaking news in the past few weeks has been the maiden flight of Europe's first over-the-tonne category drone, the Alenia Sky-X. The demonstrator took to the air at Vidsel in Sweden--an airspace that had also been investigated by another, although lighter, turbojet-powered aircraft, the Saab Sharc. Both aircraft are demonstrators by the way and, interestingly, both manufacturers are part of the broader European Neuron Ucav unmanned combat aircraft research project. The Sky-X took off at a speed of 125 knots and landed at 120. With a full payload complement of 200 kg its maximum take-off weight is 1200 kg (100 kg more than announced earlier by the Italian company).

On the subject of Ucavs, Boeing announced that its X-45A demonstrator had achieved quite a milestone in its autonomous flight capability. Indeed, in mid-June the aircraft conducted a mission from Nasa's Dryden centre at Edwards Air Force Base and replotted its own flight plan to avoid several emitters simulating air defence radars, thereby proving that it was able to react to a dynamic threat. The X-45A then "attacked its simulated priority ground target" and performed a simulated battle damage assessment mission before returning to Edwards. The software used in the 'A for this mission will undoubtedly be a key element in the development of the 16.55-tonne X-45C J-Ucas, the first example of which is due to be completed in 2006 and readied for flight the following year. The 12-metre long and 15-metre wingspan aircraft will have a cruise speed of 0.80 Mach at an altitude of 40,000 feet courtesy of its 48.9-kN-thrust General Electric F404-GE-102D, and will be able to carry a two-tonne weapon payload with a combat radius of over 1200 nautical miles.

The construction of Boeing's contender on the J-Ucas scene, the Northrop Grumman X-45B, on the other hand, is moving apace. The forward fuselage is the responsibility of GKN and final assembly of the aircraft should be well advanced by the time these lines are read. At 19 tonnes and with 64.9 kN thrust on tap from its Pratt & Whitney F100-PW-220U the 'B is much heavier than its 'C rival. This is interesting as it might suit the needs of a certain level of dichotomy between the Navy and Air Force requirements on what could speculatively lead to an "unjoint" programme. Basically, it now appears that the Air Force needs a 45-tonne aircraft with a weapon load of 4.5 tonnes (instead of two specified in the programme), which of course is in contradiction with carrier operations. Future will tell.

Warrior Aero Marine for its part is putting the seaplane drone back into fashion, having developed the Centaur Suav24 based on the hull technology the British firm is applying to its 'full-size' six seat aircraft. The Centaur prototype was built under contract to Global Observatory and had its maiden flight on 15 May 2005. The Suav24 is, for the time being, powered by a 3.6 hp Titan 45 [cm.sup.3] two-stroke petrol engine, but the type could be followed by larger derivatives, the Suav44, 68 and 136. Optical surveillance could be located at the top of the tail fin for smooth water operations or on a fixed or telescopic mast for rough water operations. It is anticipated that the Suav24 will be used only for surveillance and listening/ observation/detection roles, with a fixed payload. More ambitious missions implying the emplacement of devices in maritime and water locations (sic) would be entrusted to the larger 44. This will be effected from the central cargo/payload area with floor above the loaded static-waterline and a single full-length gull-wing door. The even larger aircraft could be used to release survival equipment and emergency supplies. At time of writing no autopilot had be selected, although the company says that it is being developed to be pre-programmed for an entire operation with multiple landing points and potentially active tracking. Fully automated landing, take-off and dwell (including weathering in adverse conditions) are being achieved using simple standard wind and wave sensing instruments (accelerometers), to deduce automated actuation of controls. A video is available on www.centaurseaplane.com.

Power

Turbine Technologies is a new member of the drone engine club. Hitherto a firm specialising in educational laboratory equipment, including turbines for tuition and test purposes, Turbine Technologies is now making its first step into airworthy powerplants, but in no mean manner since its new multiple-fuel PT50 is being investigated as a potential turboshaft candidate for the AAI Shadow 200 re-engining programme, with the company under a US Army Missile Command contract (Turbine Technologies is also in negotiations with one of the Darpa's contractors regarding the Organic Air Vehicle-II programme, which resembles the Bertin concept seen here, but in a heavier, 60 kg form). The PT50 weighs 13.3 kilos (dry) and is given time between overhauls of 2000 hours. At time of writing, a non-conforming turboshaft engine prototype had logged over 20 hours, but a near-production standard PT 50 should be running by the time these lines are printed.

As announced earlier in Armada International, Zanzottera in Italy is developing a new liquid-cooled engine. The author has recently met Guido Zanzottera who explained that his new diesel 998 had a high level of redundancy and back-up modes. First of all, the word double applies to almost any accessory like ignition, injection, operating mode and processing unit. The latter has an auto-correction function in that it enables to double feed any injector should the other fail. Not only is each bank of cylinders individually cooled, but should a serious failure occur the engine is still able, through this auto-correction function, to operate on any pair of cylinders and this includes two on the same bank or two on separate banks. All engine parameters, including vibrations, are relayed to the ground station via datalink. While the bare engine weights 24 kilos, the weight of the complete unit jumps up to 47 kilos. But then, this single-litre capacity engine produces 80 horsepower, which is no mean specific output.

New Drone Playground

In a major development, the hitherto named West Wales Airport has seen a major overhaul of its facilities and usage under the impetus of the Welsh Development Authority to allow the operation of unmanned aircraft in civilian airspace. Now known as Parc Aberporth, the airfield will stage a major event on 6 and 7 September with already eleven (at time of writing) drone companies registered to demonstrate their wares.The site is close to the coast, an area that is already used as a Ministry of Defence missile testing range operated by Qinetiq. For the time being drone flights are still authorised "per application only". Unmanned aircraft are authorised to take off from the runway and fly towards the coast for testing purposes, but the Stakeholder Group, which took over the private airport, is still currently negotiating with the civil aviation authorities to lift, or partially lift, drone flight restrictions.