Typhoon FCS and Flying Characteristics
Thanks for the montage Nick, I was writing this as you posted.
All right you lot, anyone here done a display in Typhoon??
No? Well pin your ears back because I have.
I have no intention of commenting on what may have led up to the subject incident, I will give you some facts about Typhoon flight controls and flight characteristics as there has been some speculation and questions raised in these regards.
Typhoon has Carefree Handling (CFH), which means that the pilot need not worry about exceeding any structural or aerodynamic limit no matter what he does with the controls (stick, throttles or rudder), no matter what the prevailing flight conditions are or what fuel state or weapons load the aircraft has. However, it does not mean that the pilot can ignore the basic laws of physics and aerodynamics.
The basic airframe configuration is also aerodynamically unstable in pitch, which helps to explain BOAC’s observation that there was “not much alpha on the foreplane”. The control surfaces move to artificially stabilize the aircraft. In a stable aircraft the control surfaces deflect to make the aircraft pitch. In an unstable aircraft the control surfaces are ‘stopping’ the aircraft from pitching. If you look at pictures of the jet in a hard turn, the foreplane is actually leading edge down (ie going against the turn). The flight controls are constantly on the move to keep the apple cart balanced.
The stick does feature an override or detent, but this only produces an effect when the aircraft is in a g-limiting condition (higher speeds) where a percentage of extra g is then allowed. This was the subject of a lot of discussion and heart ache throughout the design life. Some folk insisted on it being there (despite the high fatigue penalty of its inadvertent use) to cater for the high speed dive into the ground (or mid-air collision avoidance) where 9g wasn’t going to hack it, the extra % might just make all the difference. However, this was in the days before GPWS was part of the baseline design. In actual fact the window where 9g would kill you and 9+x%g would save you is very small indeed, but that’s irrelevant to this story because it is highly likely that the aircraft was a speeds where it would be alpha limited not g limited.
The biggest factor that nobody has picked up on is the ability of the aircraft to increase its energy state in a heartbeat. Unload for 3 secs and you add 100kts or so, the faster you are the faster you get faster, with the burners in at low level you can find yourself accelerating despite being at 9g. Not something the current fast jet force are used to!
That should be enough to keep you going and set a few facts straight.
Regards
Tarnished