Graham Warwick/WASHINGTON DC
Flight testing of the ALE-50 towed decoy on the Boeing F/A-18E/F has revealed that heat from the engine exhausts burns through the cable when afterburners are engaged, and can melt cable insulation and short out power to the decoy when engines are on full unreheated power.
The problem is revealed in the annual report to Congress by the US Department of Defense's Director, Operational Test & Evaluation (DOT&E). The report identifies deficiencies with several other weapon systems now in various stages of development.
The towed decoy issue has been tackled by adding a "goalpost" under the aft fuselage to hold the cable away from the exhaust. This is expected to allow full unreheated power to be used in manoeuvres up to 6-6.5g with a decoy deployed, and afterburners to be used "for a limited time" up to 2.5g.
The F/A-18E/F will actually be fitted with a different, fibre-optic, towed decoy, but the exhaust effects are expected to be similar. There are concerns, the DOT&E report says, about possible chafing of the fibre-optic cable on the goalpost.
Other concerns noted with the F/A-18E/F include a potential 42km (22nm) reduction in fighter escort combat radius resulting from a solution to the manoeuvre wing drop problem, and acceleration in 1g flight and at supersonic speeds which is slower than that of the current F/A-18C/D.
Deficiencies identified with other aircraft include:
B-2 - incapable of achieving the required sortie generation rate, and cannot be deployed, because of unreliability and difficulty maintaining the low observable surface; C-17 - formation airdrops require increased aircraft spacing, and jumper exit rate, time over drop zone, station keeping and wake vortex issues remain; T-6 - limited envelope for spin entry and significant concerns with variability of stall characteristics; V-22 - the severe proprotor downwash issue is still unresolved.Deficiencies are also identified with various weapons, including:
Advanced Medium Range Air-to-Air Missile - deficiencies noted in beam aspect attacks and against targets using self-screening chaff. Joint DirectAttack Munition - testing delayed by tail actuator problems and instability with penetrator and 450kg warheads; Joint Stand-Off Weapon - concern whether target location methods can provide the accuracy needed to be effective; Wind-Corrected Munitions Dispenser - autopilot deficiencies and problems with the active sensor and radar altimeter for the sensor-fuzed weapon submunition.Source: Flight International
