The flight manual for the Mirage IIIO was quite specific in prohibiting spinning the aircraft. A spin in an aircraft is when one wing has lost all its lift (stalled) and the other is still producing some lift, this usually occurs at slow speeds and high angles of attack when the aircraft enters an unbalanced state. Some aircraft spin quite easily and recover quickly once the correct spin recovery is applied. Many swept wing aircraft, high speed jets in particular, exhibit a violent spin characteristic that is difficult to recover from and use up a great deal of altitude as well. The Mirage is one such aircraft.
On this day I was programmed to fly a 2 versus 1 air combat mission with myself being the single aircraft acting as the adversary to the other two. The mission lead was Dave Pietsch and the number two was Mike Tardent who was taking over as the new executive officer of 77 Squadron. The intent of the mission was part of the refresher training for Mike. The aircraft that I had been allocated was configured with RPK-10 external fuel tanks which were designed to have 500lb bombs attached to them and as such there were large attachment points jutting out from the side of the tanks increasing the drag on the aircraft quite considerably, even with no bombs attached. See the photos below supplied by good mate Darren “Motty” Mottram and taken by Greg Andrews.
Despite the drag points, the aircraft was still capable of easily going supersonic. The Mirage also had a trait when returning from supersonic flight to subsonic flight of ‘tucking’ or pitching up with about 1.5 to 2 ‘G’ this meant that if you were pulling any ‘G’ during this transition you could overstress the aircraft with too much ‘G’. To avoid doing so you had to ease the stick forward a little and then once through the transonic region you could reapply the ‘G’.
On the first engagement of this mission I came to merge with the other guys at around 37,000ft and doing Mach 1.2 (1.2 times the speed of sound), they were well below me and I caught sight of them and commenced a turn towards them with about 4 ‘G’. Being aware of the probable onset of the ‘tuck’ and not wanting to lose sight of the pair coming at me I elected to fly ‘by the seat of my pants’ and just feel the jet through the ‘tuck’. I was looking over the side of the canopy rail with my helmet visor about 10cm from it when I felt the jet ‘tuck’ quite harshly which was unexpected however, I needed to stay visual with the attacking pair who were now climbing almost vertically to engage me.
I was confident now that the jet was subsonic and would no longer ‘tuck’ on me (I couldn’t afford to look inside at my airspeed or I’d lose sight of the attackers) and so I rolled the aircraft towards the threat and attempted a high ‘G’ turn towards them with the intent of thwarting their first attack. The first thing to happen was the canopy rail hitting my helmet visor as the jet reeled upward and over itself into an indescribably violent manoeuvre. My attackers witnessed this amazing gyration as well as a large sheet of flame shooting out of the exhaust of the engine. The jet then went into what is called a “Pitch Oscillatory Spin” which basically means it flicks violently through 360 degrees then stops momentarily in the upright attitude before again flicking. When it first stopped momentarily I thought “great we’re good” only to have it continue it’s violent downward spiraling spin. Once I composed myself and realised what had happened I started the spin recovery technique laid out in the flight manual.
Now if you look in the cockpit of a Mirage you will notice the top of the stick has a series of black and yellow stripes and the cockpit walls just below the canopy rails have corresponding stripes. The flight manual calls for the stick to be accurately aligned with the canopy rail stripes to effect a spin recovery. At this point I was bent over the stick with my head very close to the stick desperately trying to align the stripes as accurately as possible while the jet continued downward snapping the stick from my grasp each time it flicked. It seemed to me that the spin recovery was not working and the next step in the flight manual was to push the stick fully to the “in spin” direction, in this case to the right. The spin rate was so violent that I couldn’t bring myself to try it and I just continued to try to hold the stick central.
It is worth mentioning that the RAAF rules require an ejection if you are out of control with no indication of regaining control as soon as you reach 10,000ft. I thought I was fast approaching this point when the aircraft started to slow down it’s roll rate and showed signs of recovering. Now have you ever been spun around in a chair for a while and then stopped and found your eyes whipping from side to side, well that’s what I was experiencing at this point and I mis-read the altimeter thinking I was approaching 12,000ft when I was actually at 22,000ft. So my decision not to eject was a lucky one. The aircraft finally stopped spinning and I returned to what I though was normal flight except it was very quiet, a look at the engine instruments revealed the reason, the engine had stopped during the initial violent pitch and roll. So now I had to go through the engine relight procedure to get it going again which, thankfully, was successful. I then turned for Williamtown and made a straight in approach to land without any further adventures.
So what had happened to make the jet enter into the spin? Well as I came to the merge with my attackers I reduced the power by pulling the throttle out of the afterburner range to slow to subsonic speed so I could turn more tightly. Because of the extra drag of those RPK-10 external tanks the aircraft went subsonic very quickly which I didn’t perceive. Normally it would take a little while before it would slow to subsonic speed. So when I started to apply some ‘G’ and felt that “harsher than normal tuck” the aircraft was actually stalling (wings no longer producing enough lift to support the jet). There is no stall warning or stall buffet in the Mirage it just enters a mushy high rate of descent however, if you are in unbalanced flight and pulling ‘G’ at the time guess what happens? Yeah, it will spin just as it did on me.
Dave and Mike continued to conduct a 1V1 combat mission after I left them so they got some training done. Dave later remarked that he had never seen a Mirage do that initial manoeuvre before and was very impressed with the sheet of flame that came from the back of the engine he also really thought that I was going to eject. Naturally I was deservedly ridiculed for being such a “hamburger” by spinning the Mirage by everyone in the Squadron. As far as I know, although I’m not the only one to spin a Mirage, I am the only one to spin one with RPK-10 tanks on, I should’ve been a test pilot. I was asked later if it scared me but I honestly don’t remember being scared just confused and I do remember concentrating on the spin recovery technique with no feeling of being scared. I don’t think that would be the case now that I have the experience of knowing the potential for disaster with this incident and therefore I wouldn’t recommend “going for a spin” in a Mirage.