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
Limited ( TSL ) 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 that there was a place
for airships to fulfill 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 Munks Airship Developments had already
proved the concept of smaller airships with the AD 500.
The resulting merger of 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
in to 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 in to the Thermo Skyship
company and it had grown to a 30 strong design team. The
idea being that the non-rigids 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.
A de-merger from Airship
Industries in the 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
a) American Skyship Industries Inc., formed in July 1982
and based at Lansdowne Airport, Ohio.
b) 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 Coastguard
requirements during the U.S. President Jimmy Carter administration.
The hull would be of aluminum alloy,Alelad 2024-T3 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 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-rigids are cheaper to produce
than rigids 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 by the US Navy with their non
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,
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 a 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 contemporary non rigid ship, and similar
in concept to the successful US Navy type ZMC2. In 1987,
the concept RS.1 proposed as a 25 tonne payload ship for
surveillance, search and rescue,resource development and
relief work. This was later as dropped and the company moved
to a smaller non rigid design of ship, the ANR 1.
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 themselves 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 company documentation it was quoted that
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 in to a 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 favor of a composite carapace.
For ground clearance at take off, the tailfins were placed
in an X configuration.Twin Allison 250 - B17C turboprops,
each of 420hp totaled some 840h.p. 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 horse power 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 a 8 ft 3 bladed propeller and
engine at each wing tip, and can be rotated for 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 an/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 pllenum 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
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
over 1989 and into 1990.
Hangar Storm Damage
It was during a gale
force storm on Friday 13th January, 1989, 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 was erected to protect
the interior of the hangar. Two months after the storm,
on 13th March, the envelope was re-inflated inside the hangar.
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 some 22 months. The
tear was repaired and the envelope re-inflated in September
1989. By November 1989, it was decided that a new a stronger
Kavlar 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 it's design, would
not allow the envelope to stretch change shape, and therefore
designed to be similar to that of a metal clad airship such
as the US Navy ZMC2, and the original R30 metalclad 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 enveloped 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 the test area, it was
decided that the new aramid envelope was required. Investigation
in to the envelope self deflation, no cause could be attributed
to it. With the new envelope, it was seen than 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 carefully
rigged and attached to it.This added addition 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 shape.
Moving in to the new
decade, by August 1990 saw the avionics, fuel systems and
main pilot controls 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.
With an oil price
shock, the ending of the Cold War, and the considerable
drop in defense spending, added to that spiraling inflation
rates for many countries, the world was plunged in to 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 in to 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 the 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,
of 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
was 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 later dismantled.
The same financial recession and liquidation problems also
saw the closure of Airship Industries, in September 1990,
the same company which AAC had merged from.
The Jurby hangar remained
in place late in to 2009, when it eventually demolished.
If you want to see part
of this unique peice of aviation history built on the Isle
of Man, today the a 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-cart track.
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 alternatively
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 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
groundcrew, 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 Patroller airship can be found here
Special thanks to Terry Turner,
Bruce Blake and Alastair Reid for source reference material
referenced for this page.