Tony Cunnane's RAF Years

This item was written on 19 March 2010 for my now discontinued Blog

As I was idly browsing the Internet yesterday, as you do, I came across several sites dealing with ‘hammerhead’ stall turns in small competition aircraft and I was reminded of the time my instructor and I had a hammerhead in a Hunter T7 (XL609) during the early weeks of my advanced training at RAF Valley in May 1967. (Click on the image to pop up a larger version with caption)

We were operating at around 40,000 feet over Snowdonia practising what is known as ‘recovery from the vertical’. This is an essential demonstration and practice of what happens if the aircraft runs out of flying speed when at or close to the vertical – the sort of thing that could happen in combat when chasing another aircraft, or solo students can do when their aerobatics go wrong! After my instructor had demonstrated the practice without incident, it was my turn.

I pulled the aircraft up into the vertical and waited for the inevitable stall. I was told to look out to the left and keep the aircraft perfectly vertical by reference to the horizon - easier said than done since you can't see the tips of the highly swept-back wings. By good luck, rather than skill, I must have put the aircraft into a perfectly vertical attitude. I saw the airspeed indicator fluctuating wildly at less than 100 knots as the altimeter reached 43,000 feet and then stopped increasing.

Suddenly the aircraft was enveloped in a dense white mist. “Hold all the controls absolutely central”, said my instructor. Because the Hunter has powered flying controls with virtually no feedback, it was possible to hold the flying control column (aka joy stick, if you must) perfectly central using just the thumb and first finger of the right hand but that is not really advisable and I'm sure I actually held on tightly. “That’s un-burnt fuel we can see coming out of the engine intakes," continued my instructor. It appeared to me that the white fuel vapour was hurtling skywards when in fact it was the aircraft sliding backwards at increasing speed and leaving the fuel behind rather like a vertical contrail. After a few seconds, as the reverse airflow over the tail plane increased, the aircraft pitched rapidly forwards, producing a large amount of negative ‘g’. That was the hammerhead.

Now we were looking straight down, swinging gently as though suspended by the fin and rudder, onto the mountains and valleys of North Wales. “That’s the first time I’ve done a true hammerhead stall,” said my instructor encouragingly. “The Hunter usually falls out of the vertical, either forwards or backwards depending on the airflow over the wings and elevator, without sliding straight down. Interesting wasn’t it?”

I pulled out of the ensuing high speed dive and was told to climb back up to 40,000 feet and do it again, but the second time the aircraft fell over backwards with a small amount of positive ‘g’ without performing a hammerhead.

As a new trainee pilot with many hundreds of hours flying as a crew member in Shackletons and V Bombers, it seemed unnatural for such a large aircraft as the Hunter T7 to fly backwards but the experience certainly gave me added confidence in the aircraft.

I flew XL609 on 14 sorties between May and August 1967.

I am grateful to George Trussell for permission to use his image of XL609 at Wattisham in 1960. You can see many hundreds more of George’s images here