I was wondering what the differences are in aircraft that are navalised or setup for maritime strike roles. Are there any particular differences in construction or maintenance required due to operating in areas where the aircraft is/can be exposed to salt air? Or is this not a significant concern?
Take for example, a Hawk 100-series or Hawk 200-series aircraft. In order to be roled for regular maritime strike or patrol work, is there anything required to do so? Beyond the fitting of appropriate weaponry, sensors and possible external fuel tanks I mean. Does the wing/airframe need to be made out of specific materials, or does it require a special paint job, or need to be hosed down regularly?
Basically wondering what the effects/differences are for regular operations over the ocean as opposed to operating over land.
Thanks
Obviously many changes would be required if the aircraft was required to operate from a carrier, but I assume that this is not part of your question.
As you mention the key to maritime operation is corrosion caused primarily by salt spray, but also by high concentrations of the salt in damp air.
There are several factors: the length of time the aircraft is exposed, the concentration level of the salt, humidity & temperature.
In turn these are dependent on the type of operations the aircraft will be engaged in and at what altitude.
If the aircraft spends most of the time flying at 1,000m over the sea it will be exposed to a low concentration of salt, where as an aircraft, such as a helicopter spending much of the time hovering less than 30m will be exposed to high concentrations of salt.
If the aircraft are based close to the sea, less than 3km then aircraft parked outside will be exposed to medium levels of salt concentration. In this situation aircraft should be stored in hangars.
Aircraft designed for continued exposure to high concentrations of salt are constructed with materials that resist corrosion. They are also designed to avoid difficult to reach areas where corrosion can build up and is difficult to detect.
From the maintenance point of view the best way to minimise corrosion due to salt is to wash the aircraft after each flight. It is important that the water does not flush the salt into areas of the aircraft where in can do more damage; so appropriate sealing has to be considered in designing the aircraft. Special greases are often used to prevent the high-pressure spray washing the lubricant out of bearings etc.
Helicopters in particular are washed in what the US call a “bird-bath”.
The same applies to the sensors and weapons that are exposed the salt rich environment, particularly those that rotate such as turret heads.
In the case of the Hawk aircraft even in the maritime strike or patrol role, it is likely to be flying for relatively short periods 1-4hrs at relatively high altitudes 1,000m.
On strike runs it may operate down on the deck, but not for very long.
Neither the 100 or 200 series aircraft were specifically designed for maritime work, so they were not constructed using corrosion resistance material. However the T-45 Goshawk was designed for the maritime environment. If a country wanted to operate the Hawk in the manner described, a quick check with BAE Systems and they would be able to advise, which areas were modified on the T-45 to mitigate against corrosion.
As a precaution the surface coatings should be upgraded to resist additional abrasion cause by salt crystals while flying at speed close to the surface of the sea and the necessary repeated washing of the aircraft.
Modern washing systems can include additives in the water that can neutralise the affect of residual salt left on the surface of the aircraft, some materials change colour to provide an indicator of where extra washing is required. If a proper washing pan is used, most of the washing water is recovered and recycled.
When an aircraft is operated outside the environment for which it was originally designed additional maintenance is required. In this case further inspections of the aircraft looking for corrosion would be required. If the aircraft is used for additional low flying then it is likely to pull more g in the turns (the air is denser), so inspections looking for metal fatigue would also increase. (Often metal fatigue is increased by a corrosive atmosphere).
In summary
I do that think that it would be either necessary or practical to modify Hawk 100 or 200 aircraft for use in a maritime role.
It would be prudent to check what changes were made to the T45 when it was navalised.
An improved paint finish is desirable.
Regular washing and a revised inspection schedule are all that would be required on the maintenance front.
The Hawk variant used would require, a radar with lookdown capability with air-surface modes, external fuel tanks and with air to air refuelling capability. The drawback is that it has a low wing so it would be difficult to integrate large Air to Ship missiles.
As far as the basic aircraft is concerned operating the Hawk is a maritime role would be relatively straightforward.
The drawback with this aircraft in this role is the lack of range.
Chris
