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F1CZ EW Modifications


Griffon345

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A long one. Taken from memoirs of Kobus De Villiers, I believe he is working on or has already published a book on his experiences:
 
Chaff and Flare & EW development.
Since the SAAF was not too happy with the Mirage F1 performance with the Station 0 Chaff/Flare pylon, I was put in a very awkward position. A senior SAAF officer had previously asked me, unofficially, to work on an alternative design since I had doubts about the pylon design.
During a later heated meeting, where the flight test results of the station 0 design were being discussed, he asked me to present my alternate design proposal. There was a stunned silence in the room, and I knew my career might be on the line.
I first need to give some background that led to this alternate design:
The Mirage F1 has two ventral fins under the aft fuselage. These were a design fix for a fin flutter failure experienced on the F1 prototype. The vertical fin was reduced in size & the two ventral fins were added for directional stability during high aoa turns. These fins were mounted via 2 high tolerance pins that were bolted into the machined fuselage frames that carried the vertical fin’s loads into the fuselage. The ventral fins were constructed of machined frames and riveted skins. They were placed under the fuselage as dictated my aero requirements, but this also put them in an area which is subject the very high sonic loads leading to metal fatigue.
The screeching sound of a fighter passing overhead consists mainly of the hot supersonic air from the exhaust, forcibly mixing with cold atmospheric air. This causes high frequency sonic vibration and any harmonics to the natural frequency of metallic structure nearby is amplified in attachments between structures. The result of this was that the ventral fins started cracking.
We developed repair schemes, but the SAAF tasked Atlas to come up with a long-term solution. In my team were two very bright young engineers, one a graduate from Cranfield in the UK and the other an ex- Witsie with a MSc in carbon fibre structures. The latter technology was very new in aviation at the time. I asked them to design a new ventral fin. This was an official project with funding etc. It turned out to be more complex than anticipated since the sonic loads were difficult to measure during flight tests and we did not have enough knowledge about fatigue resistance in carbon fibre structures.
I had a meeting with them one afternoon and the problem kept recurring in my head. At about this time I was unofficially asked to do an alternate design on the chaff/flare issue. While listening to Bob Dylan while tinkering with a Formula Vee in my garage, the sound of his harmonica suddenly gave me an idea. If we could combine the design of the new ventral fins with long narrow rows of chaff/flare cartridges, we might just have a solution. The following week the guys started layouts and we could nearly fit the required number of cartridges in a ventral fin that has the same area as the original fin.
The new ventral fin and the cartridges would be quite a bit heavier than the original one, so we had to add an additional mounting point to each fin. This changed the natural frequency of the fin and it appeared from first calculations, that we would then avoid the harmonics that caused the metal fatigue in the first place.
So now we had a metal fin, slightly wider but with the same area as the original and it could carry nearly the number of cartridges the SAAF wanted. The only problem was that the electronics guys would have to redesign their cartridge holder and its printed circuit board.
So, when I presented this at the meeting, the big brass quickly asked how long it would take to build a prototype. The electronics guys were not happy, but we were already building 2 experimental ventral fins.
Not to long after the meeting, we had an aircraft fitted with the new ventral fins and instrumented for flight testing.
The increase in drag was so low, we could not measure it! The electronic guys came up with a very good plastic injection moulded casing and the cartridges fired perfectly from it.
The sonic fatigue problems also seemed to be resolved with the new ventral fins.
A contract was issued, and the fleet was fitted with the new ventral fins.
Of course, my boss was not impressed with my ‘gekonkel’ behind his back, and I knew I had to leave Atlas.
At this time, I was also finalising the Cheetah R2Z prototype and the SAAF asked if we could add a new chaff/flare installation on it that would carry more cartridges than the planned system.
Soon after the Cheetah R2Z completed it successful flight tests, I was advised by someone in the SAAF to consider moving to a small company in Pretoria that did special projects for the SAAF.
I went for an interview, got hired and we received the contract to design the chaff/flare system that would fit all the different Cheetah models.
271602569_10161473823630558_370833176202
 
 
271657852_10161473824210558_406590321910
 
 
271603060_10161473825730558_174309938020
 
 
271604603_10161473826295558_750039818129
 
Below is image by Herman Potgieter (RIP)
271659957_10161473826685558_151127616564
 

I believe the display fitted in the space left:

F1CZ RWR.jpg

Installed in the F1AZ as well and looked as below. Controller left and display right:

F1AZ RWR.jpg


Edited by Griffon345
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5 hours ago, Griffon345 said:

Agreed, good manual for reference available (at cost - reasonable):

https://www.flight-manuals-online.com/product/dassault-mirage-f1/

That manual can be found online downloadable for free either.

"I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war."

-- Major-General Frederick B. Maurice

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True, you can find the F1 CZ -1 manual, not the -2 with operation/ navigation hud and weapons usage.

The site quoted by Griffon45 proposes this -2 , for  example for the libyan F1 ED.

Details:

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