“Why can’t the Chinooks operate from naval ships?”
“Can air force’s new AH-64E Apache attack helicopters operate from ships”
As a former naval aviator and helicopter pilot, I often receive such queries. One came my way recently about the Indian-made Light Combat Helicopter (LCH). A reader wanted to know “is there any potential for LCH (sic) for Indian Navy?”
Firstly, that’s for the Indian Navy (IN) and Indian Air Force (IAF) to answer. I am not aware of any such operational requirement. Perhaps with the appointment of India’s first Chief of Defence Staff (CDS), who knows, this paper missile may soon land up on some desk in the Integrated Headquarters of Ministry of Defence (IHQ MoD). The helicopter’s inherent ability to operate from small, confined spaces and stage-through platforms makes it an ideal candidate for such iterations.
My quick reply to that query, framed keeping Twitter’s 140-character limit, hides many possibilities:
Now, combat helicopters can look pretty impressive and lethal. Bristling with turreted guns, missiles, rocket pods, even air-to-air missiles, they are an aviation aficionado’s delight. So, it is only natural for enthusiasts to juxtapose them with majestic warships.
Understanding Why & Why Not
The LCH, like other attack or combat helicopters, is designed for terrestrial application. They come into their own in the deserts, plains, forests, hills and – in the Indian context – even in the mountains. But we have host of things to resolve before they can turn Top Gun or tomcat at sea.
To understand why, we must ‘update’ our ‘landlubber’ status and sail hundreds of miles into the sea. That’s naval turf – salt, spindrift and a largely featureless terrain. You must know what happens when the lights go out before taking any leap of faith. (*landlubber = an unseasoned sailor or someone unfamiliar with the sea)
Allow me to play out a scenario I often speak about (cue the martial music please):
It’s a couple of hours after the sun has set into the ink blue waters of the Indian Ocean. The last vestige of daylight has disappeared into the sea, taking with it any semblance of a horizon as a naval helicopter returns for landing after a successful mission. Destination is reporting a 30-knot crosswind and partly cloudy skies on a clear moonless night. There is no VOR/ILS to help you, no aerodrome beacon, no autonomous approach or landing aids. Fuel is down to minimum, there is no diversion, nowhere else to land. And if that’s not enough, the landing pad is no bigger than a badminton court and moving about six degrees of freedom.
It’s a task that has challenged the best helicopter pilots since middle of the last century and continues to do so. The demands such missions impose on man & machine is part of the journey that makes a naval aviator. The easy part is saying “let’s go!”; everything else requires design from the sea level up, deep insights about the marine environment, key adaptations to deliver out at sea, and, finally, the patience to test and perfect.
Naval helicopters must be marinized and resilient for long term exposure to the salt laden environment. Ships have low freeboard and it is not unusual to see the helicopter engulfed in salt spray while taking off or landing. The merciless attack of elements on thousands of rotating parts continues unabated day after day, night after night. Is your helicopter up to this challenge? If not, be prepared to add extra maintenance or reduce time between overhauls (TBO). And remember, ships have other tasks and are always in a hurry, whether it’s launch, recovery or turnaround servicing. You will invite the CO and Fleet Commander’s wrath if you ask for a 2-hr cool-down for engine wash and ‘strike-down’ in hangar.
Helicopters are typically smaller, aerodynamically more inefficient and cumbersome than aeroplanes. Space is a premium on every helicopter; so is it on a ship. Is the helicopter borrowed from an air force or army design optimised for naval requirements? Chances are, it might not be. It may turn out a power ‘overkill’ at sea level that can’t be used without overwhelming the transmission, require special treatment or metallurgy for prolonged sea exposure, and definitely need to cater for realism of afloat maintenance practices.
Unlike an airplane where thrust from the powerplant acts directly along the axis of motion, helicopters are propelled through a combination of engine power, gear boxes (sometimes very intricate, e.g: unconventional, contra-rotating helicopters), rotor system (main rotor and tail rotor) and their dynamic drive chains. Every landing, every takeoff (especially Category A) sends ripples of power through this entire chain. Does the entire dynamic system cater for shipboard launch, recovery and blade-fold? Does the landing gear type/design cater for landing loads and deck protuberances? What kind of response times, cyclical stresses, maintenance requirements and limitations do they throw up independently or in combination? Ponder over these aspects before taking the air warrior out to sea.
Power Corrupts & Sea Corrodes!
In an airplane, there are thrust levers or throttles that are directly operated by the pilot. In a helicopter, the pilot acts on the rotor system, which, through governing systems, acts on the powerplant. Through complex, manual or automatic (FADEC) engine controls, the engine power levels are kept in the operational range. While landing or taking off afloat, one has to cater for two systems (the helicopter and afloat platform) that could be moving independent of each other till contact is made. This can impose sudden spikes in power requirement that performance and handling qualities must provide for. Whether the full land-based envelope will be available out on deck is a question that must be addressed through exploration and dynamic interface trials.
Get Down and Wet!
Helicopters typically have a lot more rotating parts per unit area than aeroplanes. Single or twin-spool turboshaft engines, gear trains, main rotor, tail rotor, lubrication pumps, cooling fans – all these rotating components are required to keep systems in the air safely. Failure of any critical unit may require the helicopter to land, force land or divert for landing. Remember, the only landing pad out at sea could be the deck from which you took off, a ship in company or the hostile sea below. You will not be able to whip out your phone and call ATC or the COO (Chief Operating Officer) either. If operating ‘non-diversionary’ and one engine fails, you may have to burn or jettison fuel before you land on deck or ditch. Day could turn to dusk or night. Are you ready?
Are you Secured for Sea?
Shipboard operations are among the most challenging of any piloting task. As opposed to aircraft carriers, a frigate, destroyer or corvette is not all about aviation. Small decks, poor visual cues, low visibility, dynamics of airwake turbulence, ship motion – all these form the naval / marine helicopter pilot’s ‘staple diet’. If design has not catered for such qualitative requirements ab-initio, chances are some of these may severely restrict or even preclude deck-borne operations. For example, without a basic recovery-assist and traversing system (RAST, ASSIST, SAMAHE, Harpoon deck lock, etc.), operation of the helicopter from a moving deck will be severely impaired. If adequate tie-down or mooring points have not been provided, your priceless eggbeater may even roll off the deck under certain combinations of sea and deck motion. Have your mooring points been tested to take additional loads due ship motion? Does your rotor brake work as designed? If not, your blades will ‘sail’ when they are meant to stop! (‘blade sailing’, where the rotor blades flap up/down excessively, can be exacerbated at low rotor RPM due to turbulent airflow on deck)
Get the drift? There’s need for an afloat integration process.
Afloat Integration Process
The nature of naval helicopter operations requires the helicopter to quickly adapt to a host of sea going platforms that vary in design, available facilities and capability. Such integration with a host ship ideally starts from design stage where minute details of both the ship and prospective helicopters are analyzed to obtain maximum operational capability. Quite obviously, this is incompatible with a culture where each service guards its own turf and operates in silos. Perhaps India’s first CDS can break this logjam.
Regular interactions between experts on both sides culminates in ground and flight trials for development of ship helicopter operating limitations, or SHOL as is commonly known. No sudden flight of fancy is possible at sea without the prospects of breaking a few parts. If we want elaborate cross-deck capability between assets from all arms, we have to walk the talk of afloat integration.
Land or Ditch?
Modern advances in aero engines have (thankfully) rendered the possibility of an inflight engine failure a rare phenomenon; something of the order of one in 10 million flight hours. The odd ‘abnormal’ situation one encounters in modern times usually pertain to HFACS, minor engine malfunctions or mishandled situations. There are few instances where design of engine controls lent themselves to improper handling or confusion. Then there are hazardous conditions on deck or in flight where the engine can become an unsuspecting victim. In any case, if you want to put out your whirlybird to sea, be prepared for that (rare) eventuality when you may have to make a spectacular ‘arrival’ over water. Helicopters that routinely operate over water are required to demonstrate safe ditching with floats, such that occupants have a definite chance of safe egress.
If the subject helicopter is not designed suitably with doors, emergency exits, emergency floatation gear, life rafts, guaranteed floatation time, personal survival gear, etc, it may either preclude over-water operations (by national regulations), or a conscious hazard risk assessment will have to be undertaken vis-à-vis mitigating strategies and payoffs.
An Oyster of Wisdom from the Sea
So what do we figure out from all of this? There are stringent design imperatives, key adaptations, role equipment, human factors and certification requirements behind every launch, every recovery, every mission out at sea. An air force attack helicopter may ‘look’ impressive on a naval deck; indeed it may even serve some ‘joint’ purpose. But if you do not have the patience to walk through afloat integration (even for stage-through), it is better to embark the helicopter with a pier side crane!
Here’s a quick round-up of this short discussion:
The medium is ‘hostile’ to both man and machine. Over land, one can still find some place to put her down if something goes wrong. The sea offers no mercy. That helicopters do operate with impunity from ship decks owes to a keen ‘seaman’s eye’ from design engineers, certification agencies, flight test crew, operators and maintainers who must maintain eternal vigilance.
Ships are domicile to many disciplines. There should be minimum op-logistic footprint for the aero-system and associated elements. Shippies are a tired lot, always short on time, comfort and redundancies. Product safety should be such that it supports the man, mission and machine through extended periods of deployment. We don’t want an albatross that gets sea sick each time the ship crosses outer breakwater! The good doctor may prescribe motion sickness pills for men; what about the machine?😃
Maintenance effort should be rationalized against the realities of operating extended periods in a hostile medium, far away from sources of technical support. Any activity that requires time, complex tools, procedures or ‘terra firma’ infrastructure can potentially become a weak link out at sea. Bulky maintenance ladders, hydraulic trolleys and such other equipment are best left ashore or on an aircraft carrier.
Design of helicopter, associated controls, operational and maintenance tasks, etc., must consider human factors (reduced efficiency due seasickness is a real thing). It is vitally important to have people with hands-on experience of operational missions at sea when key design decisions are made. A landlubber mentality steering key decisions will invariably turn out a sub-optimal naval product.
There are many more questions bright minds like you must ponder over before you shoot that question: “Why can’t their Chinooks embark our naval ships?”
Ah, ever seen these two beauties? One is the US Army CH-47 Chinook, other a US Navy / USMC CH-46 Sea Knight. Look similar, don’t they? Now, go ahead and ‘spot the ten differences’!
Good luck and happy landings! To my air force and army friends, here’s an invitation from the navy: “WDS on a small deck by pitch dark night”!
©KP Sanjeev Kumar, 2020. All rights reserved. I can be reached at firstname.lastname@example.org. Views are personal. Cover image from Twitter, original source unknown.