|The Hermes 450 at the 44th International Paris Air Show |
The Hermes 450 at the 44th International Paris Air Show
Third in our series on UAVs at Le Bourget Paris Air Show 2001 is the Hermes 450 UAV. Product of Silver Arrow, an ELBIT Systems' subsidiary, this UAV was displayed at the Paris Air Show and presented "in a satellite communication configuration, enabling operation at ranges beyond the line-of-sight, including a SAR payload for target detection and recognition in all weather conditions". IAI, the leading Israeli UAV manufacturer must now count with the outsider Silver Arrow on the international market. From our Special Correspondent, F. de V., June 21, 2001 (à£ European-Security).
à£ European-Security Photos
Silver Arrow was presenting their best seller UAV system, the Hermes 450, fitted with the Northrop Grumman TESAR and a satellite antenna. The fact that the Hermes 450 is only in service with the Israeli Defense Force, makes it difficult to get objective information regarding its performance. However, at the static stand, it was possible to see the air vehicle from close enough to gather detailed data. Some could question the maturity of the system.
The Air vehicle was presented with the NG TESAR antenna, however the electronics boxes were actually not fitted in the aircraft but were presented on the ground next to it (one of the TESAR electronic box is larger than the diameter of the Hermes 450 fuselage). According to the people on the stand, "the Hermes 450 will be fitted with the future NG mini TSAR. In the mean time, the TESAR is being proposed on the Hermes 1500 (a larger aircraft) to the Turkish Forces".
Although the Hermes 450 is obviously designed for endurance, this performance is at the cost of a very low cruise speed, a poor maneuverability and a very long take off and landing distance (at least 400m without wind). Indeed, the Hermes 450 does not benefit from breaks, stopping cross or flaps. There is no deicing system proposed.
The choice of the aircraft design is of the glider type than operational UAV and seems fragile and bulky.
- The fuselage fits in large container for transport. However these containers will not fit on regular trucks.
- The EO/IR payload is fitted towards the center of the fuselage and is masked partially by the landing gears.
- The large engine air inlet at the back implies a important infrared signature. The overhaul aircraft shape (straight wing, circular fuselage) degrade the RCS.
- The Hermes 450S is powered by a rotary engine (UEL A-80-1010). The cooling of such engines is known to be difficult and very often implies reliability issues. The engine does not benefit from a silencer which will degrade the acoustic signature. The electric power announced of 2.2 kW is very unlikely given the size of the alternator. Besides the announce power appears low to supply all the proposed payloads. The engine can provide only 52 HP which seems small to associate the payload capacity, the aircraft size and the endurance announced.
- The Hermes 450S is fitted with 2 UHF link and 1 C band link.
- It appears that the aircraft and payload Control is in UHF. This solution is not optimum because it implies high altitude flights to keep the communication quality (clearance of the Fresnel ellipsoid). More over, this type of data link is very easy to jam.
- The satellite antenna seems to be a model and does not appear operational as such for obvious aerodynamic and balance reasons. The antenna size will have an effect on the aerodynamic drag far out of the engine power reserve. Last, but not meast, from representative on stand, the Hermes 450 does not provide today a relay function.
Although, Silver Arrow propose "a parachute landing" for the Hermes 450, it has never been actually tested and is unlikely to be achieved. There is no airbag nor parachute trap. The size and the weight of the aircraft would imply to use a 250 m2 parachute. The structure of the aircraft with the large wingspan and its unique attachment point would certainly not resist the landing chock. The wing, landing gear and payload would most certainly be damaged in case of a parachute landing.
According to an American expert on UAV programs, "Silver Arrow propose with the Hermes 450 an unbalanced product obviously to meet very specific requirements from the Israeli Air Force. But for the international UAV market it seems too big for tactical operations and too small for MALE operations. Its artificial introduction into international competition appears only aimed at strengthening the Israeli position. "