Sentinel Empressesby GTX and Apophenia Formation On 31 March 1921 the Australian Air Force was officially formed. Soon after, in June 1921, King George V approved the prefix "Royal" with it becoming effective on 31 August 1921. The RAAF then became the second Royal air arm to be formed in the British Commonwealth, following the British Royal Air Force (RAF).
Upon formation, the RAAF had more aircraft than personnel, with 170 aircraft for just 21 officers and 128 other ranks. Initially, it had been planned to expand the force to 1,500 personnel – three-quarters permanent staff and one quarter reserves – who would serve in six squadrons: two of fighter aircraft, two of reconnaissance aircraft, and two squadrons of seaplanes. These plans were scuttled a year after formation due to budget constraints and, until 1924, the service's strength remained steady at just 50 officers and 300 other ranks. Of the six planned squadrons, only five had been raised, albeit cadre strength, and these were subsequently merged into a single mixed squadron until 1925.
An improved economic situation in 1925 coincided with the publication by (then) Group Captain Richard Williams, the Chief of the Air Staff (CAS), of a major air warfare study, "Memorandum Regarding the Air Defence of Australia". Considered prescient in many ways, it treated World War I ally Japan as Australia's main military threat, and advocated inter-service co-operation while maintaining that none of the armed forces was purely auxiliary to another.
Moreover, GPCAPT Williams argued that while geography and aircraft performance combined to make the European air strategy of bombing an enemy's homeland impracticable for Australia, air power could still provide the key to national security through control of the sea lines of communication. GPCAPT Williams suggested that the main justification for maintaining an army and navy was to prevent an enemy from occupying 'part or parts' of the Commonwealth. Command of the sea would be a prerequisite for any invasion. In view of Australia's immense challenges of distance, small population and limited infrastructure, the other two Services could never be expected to provide the necessary level of security against invasion. Aircraft with their speed, range, and reconnaissance and striking power, provided the obvious response.
A Series of Fortunate Coincidences Williams saw five main roles for the RAAF: the defeat of enemy aircraft (to establish air superiority in a particular theatre, such as an attempted invasion area); army cooperation; navy cooperation; long-distance reconnaissance over land and sea; and attacks against enemy targets on land and sea. Looking at three of those roles:
- Navy cooperation,
- Long-distance reconnaissance over land and sea, and
- Attacks against enemy targets on land and sea.
A common requirement of machines with 'good speed, ceiling and air endurance' started to form. While conventional aircraft of the day were rapidly developing they still had a way to go to fully satisfying the needs these roles demanded, particularly that of endurance over sea. As fate would have it though, Williams had spent much of 1923 in England, attending the British Army Staff College in Camberley and RAF Staff College followed by further study in Canada and the United States the following year. During this time he became acquainted with the various airship developments going on. The Airship seemed to offer a perfect fit for the endurance requirements and thus compliment fixed wing aircraft.
As a result included in the study put forward was the following proposed Force Structure for the RAAF:
- Air Superiority, 10 squadrons with 120 landplanes;
- Navy Cooperation, six flights with 36 seaplanes or amphibians plus two airships;
- Army Cooperation, six squadrons with 72 landplanes; and
- Attack, seven and two third squadrons with 92 landplanes.
Source: RHS, Memorandum Regarding the Air Defence of Australia, RAAF HQ, 21-4-25. If implemented over four years, Williams' plan would have involved an average annual expenditure of about 2.5 million pounds, while the nine year program would have averaged 2 million pounds. While that represented a huge increase over the average annual RAAF estimate from 1924/25 to 1928/29 of about 450 000 pounds, it is worth noting that the annual RAN estimate for that period averaged about 2.8 million pounds.
Air Marshall Richard Williams - Widely recognised as "Father of the RAAF".
As luck would have it, Williams' plan was supported by the government of Prime Minister Stanley Bruce over the objections of the Army and RAN who saw it as challenging their traditional domains. Having served in WWI himself and having witnessed firsthand the carnage modern warfare could generate, anything that promised to avoid this was supported by Bruce. Moreover, aircraft offered a potential further addition to his Government’s nation-building plans.
Australia was prosperous by comparison with other developed nations of the period, having quickly rebounded economically after World War I. Unemployment and inflation were relatively low by international standards, and Commonwealth revenues had grown significantly since Australia became a federation. Australia was a vast and richly resourced country with fewer than six million inhabitants, and Bruce made it his government's priority to develop Australia's economy. He also took the view that other nations could also see Australia's situation and thus the Government had to be prepared to defend it using the latest weapons at hand. The RAAF and the application of airpower would be a key part of this.
Prime Minister Stanley Bruce
Imperial Airship Programme 1924-30 Concurrent with the developments in the military realm, parallel developments were also taking place in the civilian realm. In 1924, the British Government agreed to establish aerial communication links with the far corners of the Empire. The decision was made to construct entirely new airships to serve air routes to Montreal, Canada, and Karachi, India, with the final view to have a ship to reach Australia. A plan was also made that the ships could be of a military value to have the ability to carry some 200 troops or 5 aeroplanes.
Under the aegis of this, Britain embarked on an ambitious plan in 1924 to build two massive airships capable of traversing the monumental distances between the mother country and her colonies — most importantly Canada, India, South Africa and Australia. The resulting airships would become known as the R.100 and R.101
As part of this airship plan, the British government wanted the colonies to pay some of the expense. In 1926, Bruce and other delegates to the Imperial Conference were shown a scale model of a proposed 200-metre-long airship that could make the journey to Australia in just 12 days. Bruce reacted enthusiastically and upon returning to Australia, slowly set things in motion. In mid-1927, a delegation called the Airship Mission was sent from Britain to investigate potential sites for airship mooring masts and to generally drum up interest in the scheme. This was something local politicians and newspapers were only too happy to help them achieve.
In October 1930, the R.101 set out on its maiden voyage to Australia via Cairo, Karachi, Rangoon and Singapore. Upon its arrival in Australia the R.101 was met by large crowds. Follow-on voyages would continue throughout the 1930s with the R.100 and R.101 being followed by a series of airships up to the R.106. They were soon named the Empress class with names such as Empress of Australia, Empress of India, Empress of Canada and Empress of Great Britain.
The R.101 departing the United Kingdom in 1930.
Passengers would travel in style.
Military Service When the R.101 arrived in Australia it was escorted initially by the first RAAF airship, the HMAA (His Majesties’ Australian Airship) Albatross. This airship had been acquired in 1926 and was actually the former British R.33 having been reconditioned in 1925. Although not of the latest technology it was never-the-less felt to provide an excellent training platform for new crews as the Australian airship capability was developed. HMAA Albatross arrived in Australia in 1927 by ship and was captained by Wing Commander Noel Grabowsky Atherstone. Atherstone had previously served as a Lieutenant Commander in the Royal Navy and had the rare distinction of being the only British airman to sink a German submarine from an airship in World War I — effectively leaning over the side of a gondola to drop a mine on it in a typically low-tech Great War endeavour. After the war, Atherstone sought a quieter life and moved overseas to Victoria intending to become a pig farmer. But an extraordinary offer to be part of the new RAAF Airship scheme was enough to lure Atherstone out of retirement and back into uniform albeit for a new country and new service.
HMAA Albatross (as the then R.33 prior to being sent to Australia).
HMAA Albatross.
Wing Commander Noel Grabowsky Atherstone
Second is Sometimes Better than First Over the coming years, the development of the RAAF Airship capability would develop in parallel to the developments in the civilian world, especially the burgeoning Imperial Airship Service. In 1932, the first of the RAAF’s new airships began construction – the first was constructed in the UK but the second was constructed in Australia at the newly established Commonwealth Airship Corporation (CAsC). This was to become the HMAA Cormorant and was derived from the new Empress class which itself was derived from the original R.101. A common design was also planned for the Royal Navy (the RAF deciding to focus on fixed wing aircraft) with 4 ships planned – eventually only 3 of these entering service.
HMAA Cormorant would be followed 2 yrs later by its sister ship HMAA Pelican. Both ships were 965ft (294.1m) long with a diameter of 134ft (40.8m) and with a 9,500,000cft (269ML) gas capacity. They were true behemoths dwarfing even the RAN’s largest ships, the County-class heavy cruiser HMAS Australia which was some 590 ft (180 m) long, much to the chagrin of the RAN. They also had their lifting gas changed from hydrogen to helium, which reduced payload but improved safety. This was possible thanks to the increased demand of the Imperial Airship Service coupled with the fact that reserves of Helium were discovered in Australia as part of natural gas reserves (originally Helium was seen as a by-product). Although the alternate gas provided reduced buoyancy, the safety increase was seen as worth it. Both airships were fitted with equipment to recover water from the exhaust gases for use as ballast to compensate for the loss of weight as fuel was consumed, so avoiding the necessity to vent scarce helium to maintain neutral buoyancy.
Propulsion consisted of 8 reversible Beardmore Tornado 8-cylinder inline diesel engines with 16 ft (4.9 m) two-bladed propellers each of 850 hp (630 kW) maximum or 700 hp (520 kW) cruising/continuous and allowed the airships to achieve speeds of up to 75kn (139km/h, 86mph), though a more common cruising speed was 43 kn (80 km/h, 50 mph). Range/endurance was 10,000NMI (18,250km, 11,508 miles) with typical patrols lasting 4 - 6wks although longer was achievable if need be.
In terms of crew and equipment, both ships flew with a normal complement of 60 which operated in two separate identical crews (called "green" and "gold") to allow for 24hr coverage though often there was some overlap and night operations were often at a reduced pace. Weapons complement consisted of 3 × COW 37mm guns (one on upper surface and two in the ventral gondola plus up to 14 × .303 Lewis guns. Up to 1.5 ton (1524kg, 3360lb) of bombs (typically of the 250 lb (110 kg) form) or mines were also able to be carried.
Following on from Royal Air Force (RAF) trials in 1918 with the airship HMA 23r being modified to carry two Sopwith F.1 Camels and somewhat paralleling developments in the USA, both airships were also equipped to carry a complement of 4 – 6 fixed-wing aircraft which could be launched and recovered while in flight. Upon service entry these were the new Gloster Gauntlet single-engine fighter though up to two Hawker Audax IIs (powered by the same Bristol Mercury as the Gauntlets) were also able to be carried. The aircraft served in the roles of self-defence of the airship, extended reconnaissance and in a limited strike role. Typically they had their wheeled undercarriage removed and replaced by a large hook attached to the middle of the top wing of the biplane. This allowed them to catch a trapeze from the airship and thus be launched/recovered while underway.
Throughout the remainder of the 1930s, the Cormorant and Pelican served with No. 2 Squadron and were used to develop tactics and conduct patrols. The aircraft and related were also updated based upon the lessons learnt as well as technological developments through out the decade.
Airship Construction at CAsC.
Establishing the Bedrock of the Australian Aerospace Industry Equally important, and often overlooked, is the fact that the construction of the Australian Airships, helped directly laid the foundations of Australia’s aerospace industry. Not only were the capabilities to construct and operate the massive ships critical but all the secondary industries such as raw material production, high precision fabrication industries, tool makers and skilled tradesmen, engineers and related. CAsC and later its sister Commonwealth Aircraft Corporation (CAC), supported by the Munitions Supply Board (MSB) drove the creation of a vast network of capabilities that would serve Australia well in the decades to come.
Beyond the helium production already mentioned, Australia being blessed with significant resource riches was able to develop mines for and associated production of high-grade magnesium, titanium and aluminium metals and alloys (used both as metal parts and items such as a titanium dope for the airships) as well as other related items. Such a surge in industries helped Australia overcome the effects of the Great Depression much better than most countries.
War Comes With the commencement of WW2 in September 1939, both Cormorant and Pelican found themselves being used initially to provide surveillance of Northern approaches and escort duties of transport ships in Australian waters alongside RAN ships. Anti-submarine patrols were an especial focus with fears of German, Italian and Japanese attacks on merchant shipping and troop transports heading to Europe and the Middle East.
In early 1940 both airships had their complement of Gauntlets and Audax IIs replaced by Brewster F2A Buffalos and CAC Wirraways (in a 4:2 ratio). Of equal, if not greater importance, was the fitment of both airships with RADAR. Initially this was in the form of an Air-to-Surface Vessel, Mark II, (ASV Mk. II) for anti-shipping and anti-submarine work but shortly thereafter in 1941 they were also fitted with a version of the new Airborne Interception, Mark VIII (AI Mk. VIII). With this radar and the benefit of altitude, operators found that they could routinely detect aircraft at 65NMI (120 km; 75 miles). These developments quickly led to the focal role of the airships being used the ‘eyes’ of the RAAF/RAN (the Navy having overcome previous inter-service reservations and quickly becoming a fan of the airships). In this role, they were equipped with command centres and multiple radio operators and soon acquired the nomenclature Airborne Early Warning and Control (AEW&C). Concurrent with this change of focus, the airships also had their provisions for bombs removed.
The airships would operate mainly from their bases on the Australian mainland at Amberley, Point Cook and Pearce. They would also sometimes base out of forward airfields at Cocos Island and/or Norfolk Island so as to provide forward detachments for convoy escort patrols.
Typical Airship Hangars - these being at RAAF Point Cook.
On the morning of 19th February 1942 Japanese aircraft carriers launched 188 aircraft. The main objective of their crews was attacking ships and port facilities in Darwin Harbour. This first raid was a success and was followed later in the day by a second consisting of made up of 54 land-based medium bombers. The air raids caused chaos in Darwin, with most essential services including water and electricity being badly damaged or destroyed. The raids also inflicted extensive damage on the RAAF base at Darwin and resulted in the sinking of four warships and six merchant vessels, and damage to another ten ships. One of the immediate consequences of these raids was the deployment of the Pelican to the Northern Territory to provide airborne warning of further raids. Operating inland of Darwin (and being careful to not present themselves as a target to the Japanese) but still able to make use of its radar capabilities, the Pelican and later other airships were able to provide an invaluable capability to identify and provide intercept guidance for future raids thus blunting this avenue of attack.
Following on from the Darwin raids, two more airships were added to the fleet. A year earlier, the decision had been made to convert the Empress of Australia and Empress of India to military service. The attacks on Darwin added urgency and the Epresses entered RAAF service as the HMAA Osprey and HMAA Magpie respectively. The war had effectively ceased Imperial Airship services to/from Europe in any case. Similar impressments of airships were undertaken in the Atlantic with the RN/Royal Canadian Air Force (RCAF) operating patrols with the previous Empress of Canada and Empress of Great Britain in support of UK/US bound convoys.
Upgrades A major improvement to the airships' fixed-wing aircraft complement had come when the Commonwealth Aircraft Company (CAC) devised a fully-retractable trapese hook. Once retracted, this new hook represented a huge reduction in drag compared with the previously-used 'A frame' arrangement. Another improvement came as a response to the propensity of aircraft to dance about on the trapese after the hook was engaged. Waiting for this movement to dissipate for each landing-on fighter showed the recovery of the flight. To combat this tendency, CAC devised a 'recovery ring' for the top of the Wirraway's tail. Now, after the trapese was hooked by the aircraft, the airship crew would hook this ring in turn. This served to stabilize the aircraft which could then be more quickly recovered.
At government request, CAC had shared their designs for retractable trapese hooks and 'recovery rings' with Brewster Aeronautical. Brewster then incorporated these concepts into their airship Buffalo. This lightweight hooked Buffalo was ideally-suited to airship use. However, the RAAF soon became well aware that its hooked Buffalo airship fighter was completely outclassed by the Japanese Mitsubishi Zero. A more powerful airship fighter was needed but not a single existing Allied type was light enough to suit.
Commonwealth Aircraft put forward several concepts for a hooked Buffalo replacement fighter. One was simply a specially lightened version of the CAC Boomerang. But this lightweight Boomerang it would still be some 600 lbs heavier than the in-service Buffalo and no faster. CAC had also been examining a Boomerang derivative powered by a 1,600 hp Wright R-2600 Twin Cyclone engine. A hook variant for airship use was studied but there was no getting around that proposal weighing half a ton more than the hooked Buffalo. Another solution was required.
With no viable alternative hooked fighter available, the job of refurbishing the worn-out hooked Buffalo fleet was turned over to the Department of Aircraft Production (DAP). Design work was performed at the DAP Beaufort Division offices at Fisherman's Bend. Actual refurbishment and modification work was undertaken at DAP's workshop facility at Newport, just west of Melbourne. DAP engineers concluded that the extra weight of the more powerful R-2600 could be accommodated if sufficient attention was directed towards drag reduction and providing lightweight components (such as magnesium, the production of which had been started years earlier to contribute to airship construction needs). First, a sample airframe was stripped for rebuilding.
The conversion 'prototype' was broken down into its major components. Then the major surgery began. As noted, the Wright R-2600 weighed 860 lbs more than the Buffalo's single-row R-1820. So, the first design task was dealing with the forward shift in the airframe's centre of gravity. This was addressed by extending the fuselage rearward in relation to the wings. The first two fuselage frames (including the firewall) were pared off. An additional fuselage bay (complete with a reinforced firewall) was then spliced in above the wings. By pushing most of the fuselage aft, the c/g was restored.
Drag was reduced by tackling known Buffalo problem areas - the abrupt end of the sliding cockpit hood and the blunt tail cone. The latter was addressed through lengthening the fairing. The canopy was completely reshaped. The sliding hood was better-tapered to meet the rear glazing more smoothly. In addition, the windscreen was bulged for improved visibility over the lengthened nose. The greater side area of that longer nose also dictated enlarged tail surfaces to maintain stability. Entirely new tail surfaces were developed. Using the same attachment points, a taller fin and rudder were attached along with wider-chord, straight-edged horizontal surfaces.
In 1943 all four RAAF airships again had their aircraft complements upgraded when these rebuilt fighters re-entered service. The rebuilt fighter was dubbed the DAP/Brewster Brumby (with so many changes, a new name was deemed appropriate). The new Brumby was significantly faster than the hooked Buffalo. Some experimental rearranging of internal equipment was needed to properly rebalance the converted aircraft but, once achieved, manoeuvrability was found to be excellent. It was with Brumbys that the airships would see out the remainder of the war. By mid 1945, plans were underway to re-equip the airships with the new Grumman F8F Bearcat. The heavier weight of this type was expected to necessitate the reduction in overall aircraft compliment to 4 aircraft, though this never eventuated due to the war ending.
Throughout the war, the secondary aircraft role was taken up by various versions of the CAC Wirraway. While the fighters got all the attention, it was often the two seat aircraft that were more important as they allowed for a second crewman to operate as navigator/observer/camera operator during patrol missions. Some consideration was given to replacing the Wirraways with something more powerful with developments of both the Douglas SBD Dauntless and Brewster SB2A considered. In the end though, the faithful Wirraways would remain and undergo their own series of upgrades including more powerful engines and related.
The last notable action for the RAAF airships was the Aitape–Wewak campaign from November 1944 through to the end of the war in August 1945. During this time both Osprey and Cormorant rotated in providing a constant ‘overwatch’ of Allied forces to prevent or at least warn of any Japanese air or sea incursions.
Beyond this, there was also a brief prospect of greater involvement when the USN made inquiries about the possibility of one or more of the RAAF airships being deployed North to accompany the USN fleet following the first Kamikaze attacks during the Battle of Leyte Gulf. It was felt that having a persistent airborne early warning capability would be of great benefit. That said, the decision was eventually made that the risk to the airship, even with its own fighters was too great. On the American side, it was also concluded that the use of Australian airships could potentially reflect badly on the USN who had in the late 1930s decided to abandon its own rigid airship capability.
What might have been - speculative images of RAAF Bearcats.
Don’t Forget the Blimps While the 4 rigid airships often take most of the limelight of RAAF WW2 airship operations, one mustn’t forget the contribution made by their non-rigid cousins. With the commencement of war and the relatively quick realisation that airships had a very beneficial role to play especially once fitted with radar, moves were soon underway to see how this capability could be grown. This was aided by the fact that there was a relatively strong cadre of trained airmen to call upon thanks to over a decade’s worth of airship operations. The conscription of the pair of Empress class airships was one part of this but it soon became evident that this was a limited resource and the cost of building more rigid airships was too high given concurrent demands on resources.
Into this climate, CAsC stepped up and thanks to a license negotiated with the Goodyear Aircraft Company in the USA, started production of K-class blimps in Australia. Production commenced in 1941 and eventually 11 of the blimps would be constructed. These non-rigid airships were essentially similar to the early K-class being made for the US Navy as Goodyear ZNP-K. However, there were detail differences.
The envelope of the Australian K-class (AUK) was identical to that of the American K-3 through K-8 ZNP-Ks - other than the cotton for the 3-ply rubberized envelope originating in NSW and Queensland. The engines and propellers were swapped for Australian-made units from the CAC CA-1/CA-3 Wirraway - a derated Pratt and Whitney R-1340 S1H1-G Wasp radial engine and a 3-bladed de Havilland ADH2 constant-speed propeller.
The CAsC-built blimps AUK 1 through AUK 8 were made to standards very similar to those of the USN ZNP-K. The opportunity was taken to adapt the control car for the revised gun positions planned for later USN K-class blimps. There would also be differences in actual gun armament. The RAAF-issue fore and aft machine guns were Vickers K guns - which were both lighter and faster-firing that the USN's .30-inch Brownings.
The Goodyear blimp's internal bomb bay was redesigned to accommodate ordnance of British origin - namely four 100 lb A.S. (anti-submarine) bombs. This choice proved unfortunate. Stocks of the 100 A.S. bombs were limited in Australia. Eventually, the Americans were willing to supply their 325 lb AN-Mk 17 depth bombs as a substitute. As these much larger US became available, bomb bay shackles were adjusted to resemble those of USN K-class blimps (and twin external bomb-carriers were added).
While the envelopes remained virtually unchanged through the lifespan of the 'AUK' blimps, the control cars of the K-class went through several modifications and upgrades. By the beginning of 1943, the bomb bays mods noted above were carried out along with the installation of external bomb racks. Machine gun armament changes were also implemented - the aft Vickers K-gun and its mount being deleted. The forward mount was reinforced to take the larger and heavier US AN-M2 'fifty-calibre' machine gun.
Improvements were also made to the 'AUK' sensor suite. Installed from 1944 onward, the US-made Philco AN/APS-2 antenna protruded from the bottom of the control car. To improve radar coverage and limit interference, the blimps' monopod undercarriage legs were modified to be semi-retractable. Towards the end of 1944, RAAF blimps were also retrofitted with a US magnetic anomaly detectors (MAD) - the Columbia University Laboratory MAD Mark IV B-2. This consisted of a remote sensor pod and a MAD operator's station. The MAD Mark IV B-2 sensor was housed in a streamlined pod which, in turn, fit into a fairing on the underside of the K-class - well aft and away from any interfering ferro-magnetic parts. The new operator's station - the MAD 'rack installation' - was situated near the forward end of the control car.
The K-class blimps would see service in the anti-submarine and escort roles as well as search and rescue (SAR) roles throughout the remainder of the war.
RAAF AUK Blimp seen over Indian Ocean 1944.
End of an Era With the end of the war and the rapid development of fixed wing, heavier than air platforms the time of the airships was coming to an end. The 4 rigid airships were also tired after nearly a decade and a half’s service (when one considers their pre-war service). As such, commencing in 1946 first the Osprey and Magpie, followed by the Cormorant and lastly the Pelican were retired and decommissioned. By 1948 all were gone. Their roles were taken over by a combination of long range fixed wing aircraft in the form of the Lockheed EC-121 Warning Star AEW&C aircraft (operated alongside the Constellation/Super Constellations of QANTAS) and RAN carrier-based aircraft (some former RAAF airship crews even transferred to the RAN to form a cadre of highly experienced AEW&C crews).
The K-class blimps served longer with the last retired in 1950. It wouldn’t be the end though with the type being replaced by the new N-class blimps in 1953. 6 of these N-class would see out the decade with the last blimp being retired in 1963.
For a while in the late 1950s there was a short resurgence of interest in rigid airships with possible collaboration with the USN to develop a new class of nuclear powered super airships but these never went further than paper studies.