Introduction
It was in early 1972 that a company by the name, Mercantile Airship Transportation Limited ( MAST ) formed for the development of large rigid airships. Major M.W. Wren was the Managing Director. In 1978, Thermoskyships Limited ( TSL ) was formed in the Isle of Man and acquired MAST in early 1979. Major M.W. Wren was the Chairman and Chief Executive. As a Public Limited Company, it raised £2.4 million on the London Stock Exchange towards the development of an unconventional rigid airship.
The company had been looking at a series of design concepts, one being the design concept of lenticular airship design (dubbed flying saucers), which included the proposal of using heating of the lifting gas to control buoyancy. The idea was that there was a place for airships to fill a transportation gap between fast jet air transport and slower sea transportation. It was then that Malcolm Wren and Roger Munk realised the value in joining forces, as Munk’s Airship Developments had already proved the concept of smaller airships with the AD 500. The resulting merger took place a year later on 29th May 1980, with Thermo Skyships purchasing the company for £1 million. The merger saw the prospect of putting both a large, rigid and a smaller non-rigid design airship into production.
The resulting merger, in July 1980, Thermo Skyships’ name was changed to Airship Industries Ltd.(AI). During the approximately two-and-a-half years the Thermo-Skyships team spent at AI, it proposed several abortive designs for non-lenticular rigid airships. Much money had already been put into the Thermo Skyship company, and it had grown to a 30-strong design team. The idea being that the non-rigid AI-designed ships would provide an income to build the larger and now ellipse-shaped 100-seat passenger ferry airship for intercity use. However, it soon became clear that the two airship projects could not share the same design lines and concepts.
Wren Skyships Limited
A de-merger from Airship Industries in 1982 saw the split away from the group of a smaller company headed up by Major Malcolm Wren, and the creation of Wren Skyships Ltd. The reason for this was due to the different design approaches for airships undertaken by both organisations and the structural design question of airships. Wren Skyships Limited was formed from key members of the rigid division of AIL and began operating with Major M.W. Wren as Chairman and Chief Executive, P.W.C. Monk as Technical Director and J.A. Dean as Chief Accountant. It took over the Isle of Man premises of AIL and had two subsidiary companies:-
- American Skyship Industries Inc., formed in July 1982 and based at Lansdowne Airport, Ohio.
- New Zealand Airships Limited
Original project ideas from the company, such are the R.30, which was a 1.1 million cubic feet airship, as a design response to the US Coast Guard requirements during the U.S. President Jimmy Carter administration. The hull would be of aluminium alloy, Alelad 2024-T,3, with a thickness range of .010 to .025 in. Supported by 24 longitudinal and 14 ring frames, two of which would be heavy-duty to support engines and loads. It would not have an individual gas cell, the metal hull covering being itself the gas container for simplicity and weight saving.
On operating and flight costs, the R.30 as a cargo carrier was claimed to be superior to a Boeing 737 aeroplane for ranges up to 600-700 miles, while an early 1980’s study of a passenger version between Paris and London city centres at 45 minute intervals using (using 6 airships), showed taking 30% of the existing traffic and making 40% profit after allowing £10m each for the two city centre terminals.
Studies were also made of the R.30 in a naval role, usually regarded as a non-rigid reserve. The view that non-rigid products are cheaper to produce than rigid and were starting to prove themselves at the time. Another advantage of a non-rigid airship was that they could be manufactured and assembled in different places, removing a possible constraint of the need for hangar space. The idea of a “metalclad” airship was to improve on the concepts gained by the US Navy with their non-rigid experience.
The Chief Designer, Mr Pat Monk (not to be confused with Roger Munk of Airship Industries) joined the company in 1980 from New Zealand Aerospace and the Wren Skyships Design team, engaged in designing a sophisticated, metal-clad airship, the RS.1.
In 1982, the R.30 concept was later redesigned as the RS.1 and was to be 420ft long with a maximum diameter of 83.25 feet. Two balloonets would give it a pressure height of 5,000 ft, and hold 1,592,000 cubic ft of gas. The RS.1 would be powered by 4 Airesearch TPE 331-15 turboprops. The design speed at flying at 5,00ft would be 149.3 mph, or at sea level cruising with 3 of the 4 engines at 121 mph.
At the time, the RS.1 was designed as much larger than the Airship Industries Skyship 600, it’s a contemporary non-rigid ship, and similar in concept to the successful US Navy type ZMC2. In 1987, the concept RS.1 was proposed as a 25-tonne payload ship for surveillance, search and rescue, resource development and relief work. This was later dropped, and the company moved to a smaller, non-rigid design of ship, the ANR 1.
Wren Skyships becomes Advanced Airship Corporation (AAC)
At a board meeting on 16th September 1987, Major Malcolm Wren stepped down as executive chairman from the board due to health issues, and Brigadier John Hooper was appointed to as Chief Executive of the company. In 1987, Wren Skyships Limited was then reorganised and became the Advanced Airship Corporation (AAC), which was formally incorporated in February 1988.
The new company, AAC, based itself on the Isle of Man, with the understanding that a cost-effective link between the UK at Liverpool and the Isle of Man could be used. Traditionally, the island was serviced by small regional airlines, and the Isle of Man Steam Packet Ferry Company, operating a ferry service, to connect Dublin and Liverpool. Wren Skyships undertook a feasibility study and knew there was a market to ferry workers to and from the Island, from both the United Kingdom and Ireland. From the company documentation, it was quoted that
“The Isle of Man makes an idea operating base for the initial routes under consideration. Since these will be new routes e.g. Jurby to Preston, route allocation will not present a significant problem”.
The concept of the ANR was to fill the role to be a competitive passenger transport on routes up to 80 nautical miles. The concept design was to fill the role and take on airship operations beyond the tourist flight sector, which had been established by Airship Industries operations using the Skyship 500 and 600 models, and into a regular point-to-point passenger service. To this end, the ANR was designed with a maximum speed of 95 mph compared to a Skyship 500’s maximum speed of 67 mph. The ANR was designed to be a comparative passenger transport aircraft over short ranges.
ANR 1 Design
Construction of the prototype ANR 1 was commenced. The ANR 1 was a smaller ship design, and AAC obtained enough funding to commence the project. Attention to streamlining was a focus of the design team of Murray McGregor as Chief Designer, followed by Bruce Blake, with the intention to make it faster than existing airship concepts. Three new design features which stood out were:
- balloonets at the extremes of the ship
- Retractable handling lines
- Balloonets in the extreme bow and tail of the ship were to save around 30% of fabric weight, in comparison to contemporary non-rigid designs. Another idea of having he balloonets at the extreme ends of the envelope would also improve control of the airship’s trim, along with giving a higher pressure to the envelope at the nose and tail.
For streamlining, the mooring cables were to be designed to be drawn back against the hull in flight, and the mooring battens common in other non-rigid airships were dispensed with, in favour of a composite carapace.
For ground clearance at takeoff, the tailfins were placed in an X configuration. Twin Allison 250 – B17C turboprops, each of 420hp, totalled some 840 hp. As turbines are heavier on fuel than piston engines, priority was for high speeds by airship standards over short ranges, rather than long endurance. The weight of the gear to retract handling lines in flight would be offset by the turbines’ lower weight per horsepower than piston engines.
The ANR 1 Allison engines were attached via a 25.42ft (7.75m) stub wing, which also contained the 1,272 litre fuel tank, attached at the rear of the gondola, which has an 8 ft 3-bladed propeller and engine at each wing tip, and can be rotated from 75 degrees to 30 degrees down. The deflection of the slipstream may be increased to 90 degrees by the deflection of a single trailing edge flap.
To help with control, the ANR was planned with both bow and stern thrusters. These were low-velocity cold air jets which could be vectored to provide pitch and/or yawing moments and vertical and/or sideways forces. The low velocity jet produced a minimum thrust of 27gh. Ballonet air was designed to be used as the supply reservoir, boosted by two fans. The air passed to the plenum chamber and thence to one pitch and two yaw ducts. With the fans running stalled, thrust is immediately available when a duct valve is opened. This system was designed to assist control at low airspeed, less than 10 knots, and during a hover. Such a system avoids the complication of placing a fan at the thruster, which could be difficult mechanically.
The construction of the new shed was commenced at the old RAF Jurby airfield on the northern tip of the Isle of Man, began on 14th March 1988, and erected in a period of almost of 4 months to the day, when the first ceremonial “sod cutting” day, the shed was completed and officially opened on 14th June 1988.
ANR 1 Construction
Construction of the ANR 1 was undertaken in the newly completed shed. In August of 1988, Airborne Industries, the airship and balloon manufacturer, delivered the envelope from their Leigh-on-Sea fabric manufacturing site. By December 1988, the prototype envelope was ready for air inflation tests. The construction of the gondola, engines and tailfins commenced in 1989 and continued into 1990.
Hangar Storm Damage
It was during a gale force storm on Friday 13th January 1989, that the main fabric door on the hangar torn and eventually destroyed. The envelope was quickly deflated in order to safeguard the airship. Temporary scaffolding and covering were erected to protect the interior of the hangar. Two months after the storm, on 13th March, the envelope was reinflated inside the hangar.
Envelope Changes
Further research and design continued on the prototype ship. In August 1989, a rupture occurred in the original nylon envelope, which had been air-inflated for some 22 months. The tear was repaired and the envelope reinflated in September 1989. By November 1989, it was decided that a new a stronger Kevlar PU type material, known as Aramid, could be used for the envelope. The envelope would be lighter, stronger and less permeable to helium gas. Due to its design, it would not allow the envelope to stretch or change shape and therefore was designed to be similar to that of a metal-clad airship, such as the US Navy ZMC2, and the original R30 metal-clad design ship. The design team was presented with a difficult choice: to continue with and fit the existing development envelope to the prototype ship, and then replace it with the newer envelope when it was available, or to wait and fit the new envelope when it was ready.
There were concerns over the serviceability of the existing development fabric for high-speed flying, even though the existing envelope more than adequately fulfilled the FAA requirements for tear strength. It was the company’s intention to use the first envelope for early low-speed test flying and then replace it with the newer envelope during the test flight programme. However, the new Kevlar fabric would be made available sooner than originally planned. After a pressure tear test on 5th April 1990 on the existing nylon envelope, a rupture occurred outside of the test area. It was decided that a new aramid envelope was required. Investigation into the envelope self-deflation, no cause could be attributed to it. With the new envelope, it was seen that an envelope change would take 2-3 months and ultimately impose a delay on the production of the ANR No.2 prototype ship.
The new envelope was delivered, and the prototype ship gondola and tailfins were carefully rigged and attached to it. This added time to the construction of the ship, and delayed the ANR 1 further final completion. Due to the weight of the envelope, it was hung from the shed roof and air inflated to keep its shape.
Moving into the new decade, by August 1990 saw the avionics, fuel systems and main pilot controls were being manufactured and assembled. The work had commenced with the ribs for the gondola already being fitted to the gondola jig. The design team expanded, and the company took on additional office space at the airfield next to the hangar.
Company Collapse
With an oil price shock, the ending of the Cold War, and the considerable drop in defence spending, added to spiralling inflation rates for many countries, the world was plunged into a deep financial recession. The impact it had on the UK economy was not felt until the winter of 1990 and so plunging the country into recession in the beginning of 1991. AAC was hampered by liquidity funding problems and a withdrawal of funding from the Middle East sources. Work on the ship finally stalled, and in June 1991, the work on the ship ceased, and 90 of the 120 staff at the company were made redundant. The remaining staff were kept on to keep a care and maintenance position for the ship and the assets, along with key members of the design team. The helium stocks, in excess of 250,000cft, were returned to their suppliers to avoid hire charges on the helium bottles.
Alternative funding was vigorously sought by the board of Directors over the next 18 months. By early 1993, funding options were no longer available, and unfortunately, Advanced Airship Corporation went into liquidation on 1st March 1993. By 27th April 1993, the ANR 1 airship gondola and envelope were sold to Lindstrand Balloons at Oswestry and delivered to their premises. The gondola was later again transported to Aviodrome, Lelystad airport in the Netherlands. Receivers sold the property owned by the company on 27th September 1993, and the shed was later dismantled
.The same financial recession and liquidation problems also saw the closure of Airship Industries in September 1990, the same company from which AAC had merged.
The Jurby hangar remained in place late into 2009, when it was eventually demolished.
ANR 1 Today
If you want to see part of this unique piece of aviation history built on the Isle of Man, today, the segment of the composite nose carapace, one fin structure and one ruddervator can be seen on show at the Isle of Man Motor Museum. The Museum is located on the same Jurby Airfield where the AAC were based.
Sadly, today, all that remains of the hangar at Jurby is the low outer wall, within which is the service area and parking for the nearby go-kart track.
Advanced Hybrid Aircraft – Patroller 3
The chief designer, Bruce Blake, went on to form Advanced Hybrid Aircraft (AHA). The Advanced Hybrid Aircraft team has prepared the design of a new and affordable hybrid aircraft named Patroller 3, or simply P3. This aircraft can fly low and slow, or can dash at higher airspeed and higher altitude in pursuit of a land or sea target. The purchase and maintenance costs are affordable, whilst the operating costs will be much less than those of current manned aircraft and rotorcraft. The energy-saving P3 can loiter at low power for as many as three days, approximately 70 hours, over a site of interest (bay, border crossing, sea-lane). At cruise power setting, on three engines, the endurance of 30 hours is suitable for quickly scanning a border or coastline.
The P3 is helium-filled (similar to an airship), and it derives 75% of its lift from the buoyancy of the helium (aerostatic lift). The remaining 25% of lift (100% total) is derived from the wing and the airframe-lift (aerodynamic lift of hull and stabilisers). Thus, the Take-off weight may exceed the aerostatic lift by 33% or more
The AHA team have already had a scale prototype for testing purposes. The design configuration has been flight tested using a 40% scale R/C prototype. The main aim was to prove that both Take-off and Landing (and taxiing) may be accomplished on the airfield with NO ground crew, simply under the control of the Pilot. Historically, small non-rigid airships or “blimps” require a groundcrew of 10-15 strong men.
More details on the new airship project and the Patroller airship can be found here
Special thanks to Terry Turner, Bruce Blake and Alastair Reid for source reference material referenced for this page.