The Australian Mirage/Draken hybrid - the 'City of Hobart'

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‘City of Hobart’ - RAAF Mirage IIIC with a Rolls Royce Avon engine.

Introduction and History

The Rolls Royce Avon was among the greatest of the early cold war jet engines, powering subsonic fighters and strike aircraft like the Swift and Scimitar, long range bombers such as the Canberra, and high-performance fighter-interceptors like the Swedish Draken.

The Australians were highly familiar with the Avon, converting their license produced F-86 Sabres into the CAC Sabre by incorporating the Avon engine. Because of their familiarity with the tooling, operation, and maintenance with this engine, when RAAF was purchasing the Dassualt Mirage III, they were offered the choice between the French Atar 9C engine and the Rolls Royce Avon. Aside from Australia’s familiarity with the Avon engine, French representatives doubted Australia’s willingness to buy an aircraft without a major British component.

As such, this modification was seen as critical to the sale of the aircraft. Australian representatives were told that the modified airframe would be ready in 28 days, a deadline that was reached, a considerably impressive feat for such a major modification. The airframe in question was converted from a Mirage IIIC and christened ‘City of Hobart’.

Static engine tests began on February 7th 1961, and test flights started on February 13th. By early May, it was concluded that the low altitude advantages of the Avon engine were not a significant improvement, and it was actually a hindrance at higher altitudes (above 40 000ft), although the Avon engine was able to achieve higher speeds below 45 000ft. However, the Atar engine was lighter, cheaper, and subjectively easier to manufacture and service. As well as this, no other prospective purchasers were interested in Avon powered Mirage IIIs.

On the basis of cost and simplicity, no further airframes were converted, and RAAF Mirage IIIs were purchased with the French Atar engines. ‘City of Hobart’ was converted into a prototype Mirage IIIE, the version on which Australia’s aircrafts would be based.

Specifications

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Dimensions: Length 15.03 m (49ft 4in); wingspan 8.22 m (27 ft); height 4.5 m (14ft 9in).

Weight: Approximately 7049kg (empty), 13699kg (max)

Engine: Rolls Royce Avon Mk67 (RB146)

Thrust: 12,500lbs static thrust, 16000lbs with reheat

Maximum Speed: Approximately Mach 2.2 at 35,000ft, exceeding Mach 1.14 at sea level.

Max altitude: 55,000ft

Cannons: 2x30mm DEFA, 125 RPG

Missiles: One Matra R530 and either two Sidewinder AIM-9B or two Matra R550 Magic air-to-air missiles

Ordnance: Six Mk 82 227 kg (500 lb) bombs or three GBU-12 laser-guided bombs.

Images

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City of Hobart Mirage III 2

City of Hobart Mirage III 4

Sources

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The RAAF Mirage Story - Wing Commander M.R. Susans, pp. 1-17 (available here) - M.R. Susans oversaw the procurement of the Mirage III for the RAAF

A3 - Dassualt Mirage III - Royal Australian Air Force, pp. 419 (available here)

RAAF Museum: RAAF Aircraft Series 3 A3 Mirage III

The Aeroplane and Astronautics, May 25, 1961 - compiled in The Aeroplane and Commercial Aviation News, 1966, pp. 586-587

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Absolutely yes, it’d make a good premium addition to an Australian tech tree where the III.O would be in the regular research tree.
Although classifying it as “Australian” is probably controversial, since it was developed by the French at their own behest with no specific input or request for it from the Australians to my knowledge. However, it was nonetheless developed specifically to market to Australia, and donned the RAAF roundels for its entire existence, so yes, I’m going with “it goes in/with an Australian tree and carries the Australian flag in game”.
I have also heard it suggested that while Australia opted for the cheaper French Atar engines, given the issues they had with them it would have been better if they selected this Avon powered Mirage in hindsight.

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This suggestion prompted me to search the National Archives for what might be sitting about on there with regards to our Mirages and lo and behold, the first search result was this excellent, official document on comparing the Atar 9C engine and the Avon.
https://recordsearch.naa.gov.au/SearchNRetrieve/Interface/ViewImage.aspx?B=3185251
There is great info, but I noticed something important as well relevant to your post. The Australians tested the City of Hobart with two different afterburners, one 28" and one 36". It would seem your comments with regards to the Avon being worse at higher altitudes was specifically for the 28" Avon as the 36" was deemed better in almost every regard. And the report concludes that if the Avon was adopted, we should have used only the 36".

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This is fantastic information, thank you for taking the time to find this and for sharing it. When I’m back at my PC I’ll make the changes to the suggestion and add this as a source.

As an aside, I’m always incredibly envious of the Australian National Archives. Having basically every imaginable document organised, digitised, and available for free to the entire world is amazing, and really puts other archives and their extortionate fees to shame.

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How does a prototype from 1961 carry GBU’s from 1976?

Uhh, sekrit documents?

Personally, I would prefer to see it go to the French tree, since Britain already has the SA Mirages they can get.

I did a quick Google search and found this: https://www.airforce.gov.au/sites/default/files/2023-07/A3-Dassault%20Mirrage%20III-%20%20pp418-423.pdf

image

It was probably a later addition and would have no actual way of guiding the bombs. F-4F is the same, could use GBUs but with no means of guiding them they haven’t been added.

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I guess that’s for the Mirage IIIO in general, not that specific trial airframe with the Avon…

Well, I of yourse would prefer a completely different variant, the Swiss Mirage IIIS C.70:

  • Different radar (derived from the radar of F-106) and avionics
  • Canards
  • Ability to carry SARH AIM-26 Falcon
  • RWR / Countermeasures

This would be a quite unique aircraft, setting itself apart from other Mirage III derivatives…

But then of course I’m biased here somewhat, haha!

2 Likes

There aren’t enough Mirage 3s in the game given how widely they were used and how many modifications there are.

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Yeah I was thinking about this as well. Clearly the Australian Mirage III.O ended up with a GBU-12 capability, but the City of Hobart couldn’t have had them and shouldn’t have them in War Thunder, given it was an early '60s prototype. The 1x Matra 530 and 2x AIM-9B would be one option and the 6x 500lb bombs another option. Or some combination.

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I think this’d actually be cool. The Mirage III would feel so much better without the Magics at a lower BR.

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