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Avon engines

kaiserbill

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Hi all

I've done quite a bit of searching on the net, but cannot seem to find details on all the Avon series engines with physical characteristics and timelines. Any pointers would be much appreciated.

On this topic, I've seen the Mirage III originally touted for Australia was fitted with an "Avon 67" of 7200kg thrust. Does anyone know what this engine is, as info is scarce. Is it an Avon 300 series engine? What were the performance figures of the Mirage when fitted with this engine over the Atar?

Lastly, am I right in assuming the Avon was a more modern engine in concept than the Atar? I've read that the Atar has it's roots firmly in WW2. This being the case, why wasn't the Avon more successful on the world market? Apart from Sweden, it doesn't appear to have been used by non-British manufacturers....
Surely something like the Mirage F1 could have benefitted from some of the later, more powerful Avon types, like the RM6C that pushed out 5800kg/8000kg.

Was there anything inherently wrong with the Avon? Weight/throttle-ability/thirst?
 

overscan (PaulMM)

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They are pretty much contemporaries. Avon development started in 1945.

Avon was more ambitious than the Atar, initially aiming for a pressure ratio about 8:1 (eventually 10:1) as opposed to 5:1 (eventually 6.5:1). All things being equal, this meant more thrust and/or better fuel economy, at a cost in complexity, cost and potentially additional weight. Thrust to weight appears to have similar in practise though. Avon SFC (specific fuel consumption) was noticably lower than the Atar.
 

kaiserbill

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Thanks Overscan. Any idea what the weight of the Avon 300 series were? Or the RM6? I know the Atar 9K50 was about 1580kg and almost 6 meters long, which is big for an engine pushing out 5000kg thrust dry. Mind you, the later model J-79's were also big beasts at around 1700kg and over 5 meters for 10% more thrust than the 9K50.
 

alertken

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pr: on the AF RR point, I doubt this was an evil plot. Until 6/2/1987 (BA)/5/87 (RR) the fond British taxpayer owned, thus picked up the losses of, both BA and RR. So, BA "chose": 757-200(RR), 767-300ER(RR), 747-200B(RR), -400(RR), L-1011s, not DC-10s. Free to use its best judgement, BA chose GE/SNECMA in 1991 for 777 (for the second buy RR learned and sharpened their pencil). SNECMA+AF were/are synonymous with French National Interest, so were expected to employ voters. (I think) SNECMA has made chunks of all AF power since JT8D Mercure (Air Inter)/737-200.

ATAR was German-inspired/influenced (so was AJ65, to be Avon). RR became miffed over RAAF rejection of Avon, for ATAR, in Mirage IIIO, though no doubt pr's point rules - that Installation Development messed up the $. In Oct.1966 RR bought BSEL, in part to kill Pratt/BSEL/SNECMA JT9D competition to RB207/211. No RR offer to SNECMA to join RB211 (though such an offer was made to Allison). So GE leapt in with CF6, which led to CFM56...on...and on. Unintended consequences.
 

Pioneer

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Found this in Flight Jan 1961 article

RB.146 Avon 300. The improved
economy of this engine confers an appreciable increase in range,
and its great thrust (13,2201b dry, 17,4201b with reheat) improvest
the Mirage's already outstanding rate of climb and altitude performance.

As a side note, which I had not heard of before, in relation to the RAAF Mirage IIIO - the article also states -
The
French Mirage is equipped with the Cyrano, produced by CSF,
who on December 20 announced in Paris that the RAAF aircraft
"will be equipped with CSF airborne fire-control radar . . . the
Australian industry . . . will participate in the project." As we
go to press this decision could not be confirmed; the main
competitor is the Ferranti Airpass 2

What is the Ferranti Airpass 2? and what other fighters was it employed in?

if guns are to be fitted they are likely
to be Adens, and not the French DEFA.


Can anyone elaborate whether the RAAF seriously looked at fitting Aden 30mm cannons??

On a final note, does anyone know were I can get a profile drawing of the prototype Avon-powered Mirage IIIO, that Dassault built and tested?

Regards
Pioneer
 
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GTX

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Pioneer said:
What is the Ferranti Airpass 2? and what other fighters was it employed in?

This isn't the AI-23B as used in the EE Lightning F3 is it?

Sounds as though with the Avon, AIRPASS radar and Adens, they looked to make essentially an Anglicised Mirage III. I wonder if plans were also afoot to equip it with British A-A missiles?

Regards,

Greg
 

alertken

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Not so much Anglicised as follow-on to CAC production (Avon), and RAAF operational familiarity (ADEN) on CA-27 Sabre. Marcel Dassault did a good job in selling near-standard product (the only Oz-ments were in the cockpit, for inventory standardisation). Ferranti A.I.23 Airborne Intercept Radar and Pilot's Attack Sight System (apologies for dredging that out of memory).
 

overscan (PaulMM)

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http://www.flightglobal.com/pdfarchive/view/1961/1961%20-%200687.html

Developed as a private venture, Airpass II provides largely for automatic navigation and weapon-aiming by day or night on interception, ground support or long-range strike missions, yet the size and weight are little more than those of Airpass I, which is purely an interception system. The pilot's attack sight is identical in both instances and the Airpass II radar has many features similar to those of Airpass I.

An interchangeable nose-pack is retained, thus saving weight and simplifying front-line servicing.

Ferranti tried selling Airpass II to the Swiss (Mirage) and more generally to French and German industry.
 

Abraham Gubler

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alertken said:
Not so much Anglicised as follow-on to CAC production (Avon), and RAAF operational familiarity (ADEN) on CA-27 Sabre. Marcel Dassault did a good job in selling near-standard product (the only Oz-ments were in the cockpit, for inventory standardisation). Ferranti A.I.23 Airborne Intercept Radar and Pilot's Attack Sight System (apologies for dredging that out of memory).

Just came across this thread searching for other stuff. Marcel Dassault (actually it was Benno Claude Vallières who was president of GAMD at the time who ran the Mirage III sales campaign) did not try to sell the RAAF on the Atar powered Mirage IIIO. Quite the opposite. Dassault wanted the Mirage with R-R Avon because not only would it apparently fly better but they saw such an equipment fit as much better for export. They and the French Government saw the British and RAAF common (sort of) equipment, especially the engine, as important for the customer. They were also planning on this new IIIO (Avon powered, nose and front guns being to customer preference) standard to be the export standard for Mirage IIIs. Remember at this time (1960-61) the Mirage III had only been ordered by France, South Africa and Israel. And the latter two were at this time more of an albatross than an endorsement for wider export orders. Also beside the Australians the next two interested customers were the Swiss and Indians who were both Avon users and interested in the same performance and commonality gains that were motivating the RAAF to look at the Avon.

The issue for the engine for the Mirage IIIO was not down to the cost of integration because when approving the acquisition of the Mirage III in late 1960 the Cabinet of the Australian Government had done so on the proviso that they wanted a comparison of the Atar and Avon powered options to be considered at the contract stage (along with various local production and other equipment issues) by the Government’s Air Board (that managed the RAAF). The cost of the actual integration ended out being very small as GAMD did the engineering in 28 days though there would be later additional costs as the Avon powered Mirage IIIO would became effectively a separate aircraft to the Atar powered Mirages and GAMD’s ongoing costs as OEM of the Mirage III would no longer be carried by the French Air Force.

SNECMA did near to nothing to sell the engine and had been warned off by the French Government as they saw the Avon as an important part of not just selling the Mirage III to Australia but the rest of the world. The only people pushing the Atar where Pratt & Whitney who owned 20% of SNECMA and did their best to sell the engine to the RAAF. But as the time frame was compressed (northern Spring 1961) and the RAAF too professional these sales efforts meant little.

The main reason the RAAF didn’t select the Avon (Mk 67, aka RB.146) to power the Mirage IIIO was that the new Atar 9C (not the 9K but it was known about) in the Mirage IIIE (with extra avionics weight close to the RAAF’s eventual avionics requirement) performed very well. It was judged by the RAAF team that the Atar 9C was better for the Mirage IIIE than the Avon Mk 67. The performance advantage of the Avon Mk 67 at take off, climb and range was not seen as being much better than the Atar 9C. Whilst at over 40,000 feet the Atar 9C performed better. Plus the growth options of the Avon Mk 67 were limited and to go to the next Avon would require a wider exhaust pipe countering improvements in performance. The RAAF assessed that if growth was needed the Atar 9K would be much better in a Mirage IIIE than a more powerful Avon RB.146. The Atar was also lighter, cheaper and more rugged than the Avon and with all the benefits of commonality with the French Mirage III through the life of the aircraft.

So the Air Board decided in May 1961 to select the Atar 9C and hold an option up until September to go with the Atar 9K. This option lapsed as there had been no 9K testing by then and it was seen as too risky. Though this would be a very interesting What If… The RAAF Mirage III team had also looked at changing the armament from the French standard to either Ferranti Airpass or Hughes TARAN systems. But recommended against it. These armament options were considered in whole with associated missiles. I don’t have data on the weapons but I would assume since the Cyrano was linked to the Matra R.530 medium range missile (AIM-9Bs were also to be carried under the outer wings) that such missiles would be the Red Top and AIM-4 Falcon. In which case the high weight of these missiles would have been significantly disadvantageous.

My primary source for the above is The RAAF Mirage Story’s “French Connection” chapter written by AVM Ron Susans, CBE, DSO, DFC who at that time was Senior Air Staff Officer at WRE (RAAF Edinburgh, Woomera Weapons Range) who ran the Mirage III evaluation program.

A persistent story is that SNECMA won the Mirage IIIO engine because they had confused the exchange rate difference between the Australian Pound and the Pound Sterling. I have found no evidence of this and since SNECMA sent an executive team to Australia to provide briefs to support the Air Board consideration of the engine options it is hard to believe they didn’t notice the difference in currency and values. The Atar was a cheaper engine because it was lighter, simpler and easier to manufacture.

I think the persistent stories that the RAAF and the world missed a great option with the Avon Mirage III and that SNECMA only won thanks to fortunate foolishness can be attributed to the ever vocal British aviation press. Who always have a good yarn, many of them are even true, as to why Britain no longer rules the air.
 

Pioneer

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Just found this interesting snippet piece of information, which I think IMO would support the notion that the Avon-powered Mirage III for the RAAF would have been superior -


“However, when Australian operations required the addition of two supersonic external fuel tanks and two Sidewinder missiles, plus the Matra, a lack of available power was apparent. As a result, the RAAF Mirage 111O was underpowered in the configuration required for our conditions. This would have been a definite handicap if offensive air interceptions had been required.”
(Source: http://www.raafa.org.au/mirage)



Regards
Pioneer
 

BlackBat242

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I too have a copy of The RAAF Mirage Story, and the “French Connection” chapter states that the Hughes TARAN radar (paired with the Sparrow, not the Falcon) was actually the main competitor to the Cyrano - for the same reason that the Avon was being pushed.

The Swiss were getting ready to buy the Mirage III, and they had expressed a strong preference for the Avon/TARAN combination (and had done extensive studies on the TARAN/Sparrow combo), but were unwilling to be the sole operator of such a variant. The RAAF's evaluation team even sent 4 of its members to Berne to consult with the Swiss Air Force, and they reported favorably on both options.

This would have meant 2 reliable and substantial operators with Avon/TARAN Mirage IIIs, which would have created a good support base for those variants.

In the end, the promise of the Atar 9K* was the deciding factor in the choice against the Avon (which was seen as being at the end of its development potential), and an option to substitute the -9K for the -9C was included in the contract... only to see that engine not enter production until 1968/69, keeping it from ever being fitted in any of the RAAF's Mirages.

Likewise, the lower cost of keeping the French radar carried the day over the US radar-missile combo.
The Swiss, however, did fit the TARAN - but with Falcon missiles, so I wonder if the mention of Sparrow on page 8 was an error.

I have seen the cost differential for the initial 30-aircraft contract as being A$44.9 million for Atar vs A$46.9 million for Avon.


* Atar 9C [9,430 lbs thrust (13,670 lbs w/reheat)]
Atar-9K [11,023 lbs thrust (15,870 lbs w/reheat)]
RB146 Avon 67 12,100 lbs thrust (15,715 lbs w/reheat)
 
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