Airship Industries Win Landmark US Navy Contract

The Sentinel 5000 will be some 41Oft in length (193ft- Skyship 600 data in brackets as a reference) for a diameter of 102ft (49ft) and an internal helium gas volume of 2. 2 million cu ft (235,000cu ft). Gondola length is 81ft (38ft) while width is 16ft (8ft). The gondola will comprise three decks which will house crew accommodation area, AEW system operations room and the airship cockpit. All avionics are presently proven and in service with the USN while control will be via a GEC fly-by-light system. Ferranti will provide the actual avionics system while Westland will build the gearboxes and drive trains required for the large ducted propulsors. The gondola will be pressurised for operations above 5,000ft while design service ceiling is 14,000ft at max payload.

Two highly economical turbocharged CRM Diesels each producing 1,790hp and one GE CT7 1700shp class turboprop will provide a maximum dash speed of 90kts while the Sentinel will have a routine patrol airspeed of 40kts at 5,000ft for an endurance of 55hrs. In a hostile environment, the Sentinel can maintain 70kts (still air) at 5,000ft for an endurance of 20hrs. In this mode the Sentinel can typically transit 1300nm in under 19 hours, something that I am sure any surface combatant commander would relish. The maximum ferry range (unrefuelled) is 3,500nm and naturally the Sentinel can hover-refuel from any surface ship in the fleet. This is in fact something that it would do every second day or so as a routine manoeuvre during the course of a deployment.

The ODM will be configured with a standard AN/APS-125 radar from a USN Grumman E-2C Hawkeye. Development by Airship Industries and Westinghouse of the initial ODM will take place over the next three years while from 1990 through to 1992 the ODM will deploy with the fleet in a series of evaluation tests to ensure not only that the concept is viable but to also expand upon the mission capability of the initial example. This should not be a difficult task as the potential uses of such a large airship are many indeed.

Navy strategists are already looking to give the Sentinel an ASW capability in addition to an over-the-horizon ASCM role. In the ASW role it is noteworthy mentioning that, unlike a regular aircraft, the airship can hover and deploy a highly sensitive dunking sonar in addition to regular sonobuoys. This ability could be vitally important during the coming decade as a new generation of very quiet deep diving Soviet strategic missile submarines seek refuge beneath the Arctic ice floes, an environment in which normal sonobuoys and fixed wing aircraft do not shine. It has also not gone unnoticed that the Sentinel might also be able to perform a more than adequate minesweeping role.

But what about vulnerability? How can anything so big and slow evade hostile combat aircraft, says the man in the air force uniform.

Unfortunately for airships, the historic sight of the demise of the Hindenberg at Lakehurst in 1936 has tended to colour many observers’ opinions of the craft. Hindenberg was a technical dinosaur compared with today’s modern airship design. Inert and totally safe helium has replaced volatile and highly inflammable hydrogen as the lifting agent. Modern materials now allow a non-rigid airship, without the mass of steel trusses and framework associated with the leviathans of the early decades of this century. Additionally, Airship Industries’ unique thrust vectoring system also allows a close-in manoeuvring capability in even the worst weather conditions that would have easily defeated the older machines.

Therefore what we have in the Sentinel is a virtually radar-transparent flying machine. Even the gondola is built of composite materials and the already low infra-red signature from the engines is easily shielded within the aft portion of the gondola. What will naturally give away the presence of the Sentinel is, of course, the large transmitting AEW radar. However, your average inbound interceptor or long-range maritime patrol aircraft will know that you have him nicely locked up at least 100nm away. If he does make it to a firing position against the Sentinel, assuming that the patrolling Tomcats and Hornets, or the neighbouring surface vessels with their long-range SAM systems, haven’t already made a collect, then the Sentinel may well be in a position to claim the kill itself. How?

The reasons are simple. Naturally the Sentinel will be armed with an appropriate self-defence capability. This would typically comprise Amraam medium-range guided AAMs in addition to Asraam short-range IR guided AAMs. Added to this would be an on-board defensive avionics suite in the form of a tactical jammer and as a last resort that old naval standby – chaff and flares.

Inbound, Ivan in his Forger may well consider just how he will prosecute his attack. Firing his cannons into the balloon will be akin to swatting an elephant with a flyswatter. After all, the intel report did say that the airship has an internal pressure of a mere 0. 00703kg/cm2 – roughly equivalent to the pressure remaining in a flat car tyre. Therefore, even with several hundred well aimed 20 or 30mm cannon rounds through the giant balloon, it will take hours to gently sink towards the ocean, if at all as the Sentinal will feature active damage control measures in addition to multiple gas compartments to cater for just such an event. Ivan cannot take it out with an IR missile either as there is virtually no heat source and if he gets that close then the Sentinel will surely score him on his exit with its own Asraams. On the other hand that is assuming that the Sentinel hasn’t already prosecuted a successful Amraam attack prior to the hostile achieving either a close-in missile or gun attack. Nyet!

As you can see, a properly armed airship can stand and fight alone as much as a corvette, frigate or destroyer can. And that is the whole crux of the US Navy’s interest. They rightly think of it as a ship while most air force’s think of it as a plane. As a ship, albeit a flying ship at that, it does not have to concern itself with falling prey to every surface combatant’s primary foe – the attack submarine. Additionally it carries its own AEW and can transit at speeds undreamt of in surface ships.

Weather is not a critical problem either. During WW2, off the wintry coast of north east USA, in airships that were not as capable as the Sentinel, the USN was able to fly more than 87% of the time. In fact, at sea, if you couldn’t fly, the airship you would not be able to launch carrier aircraft anyway and in gale force conditions the large airship can ride out the storm probably more comfortably than can the smaller surface vessels.

So Bond’s big gamble looks to have paid off and though Airship Industries is now an Australian owned company, we won’t unfortunately be seeing any of the resulting workload. Though eventual series production of between 40 and 50 USN Sentinels is anticipated, the 1000 or so jobs created will be situated in North Carolina.

The USAF was also beginning to evince firm interest in the Sentinel as we closed for press. USAF perceive a real threat in the next decade from submarine and long-range blindfire-launched supersonic cruise missiles attacking America’s coastal industrial enclaves. The USAF is beginning to suggest that the only effective long-term remedy would be to adopt the Navy solution of the advanced technology AEW airship.

Airship Industries are now working hard on winning this contract which is something that also is being noted carefully at Canberra’s Russell Hill. With continuing delays in the RAAF actually issuing an RFP on AEW, it may well come to pass that our eventual solution is the same as the USN. It is all certainly worth watching!