The Harrier VTOL jet is able to rotate its engine nozzles at any speed & power setting. Not only for vertical takeoff/landing, but also for VIFFing…making radically tight, controlled turns. Theoretically, in a dogfight, this can be used to out-turn an opponent despite the Harrier’s relatively high wing loading.
The interesting video in this post shows a US Marine Corps (USMC) Harrier Jump jet showing the aircraft unique “VIFFing” capability (with VIFF standing for Vectoring in Forward Flight).
The Harrier VTOL (vertical takeoff and landing) jet in fact is able to rotate its engine nozzles at any speed & power setting. Not only for vertical takeoff/landing, but also for VIFFing…making radically tight, controlled turns. Theoretically, in a dogfight, this can be used to out-turn an opponent despite the Harrier’s relatively high wing loading (weight to wing-area ratio).
But how effective is VIFFing in a Harrier?
According to Paul Adam, Chief Analyst at Cassandra Defence Consulting Ltd, VIFFing is an ‘interesting technical capability, [with] virtually no real-world utility.’
Adam explains on Quora:
‘VIFFing was supposedly discovered in the early days of the AV-8A Harrier’s use by the US Marine Corps, when a pilot looked at the thrust-angle lever and wondered “what would happen if I slammed that all the way forward?” The story goes that the Harrier went from 500 knots on the flat, to 200 knots in a sharp ascent, in the time it took the pilot to break his nose on the glareshield…
‘This entered popular consciousness and was quite widespread in the late 1970s / early 1980s. There was, in particular, much media speculation in the run-up to the Falklands conflict that the Royal Navy’s Sea Harriers would be “viffing” in dogfights to effortlessly get behind enemy aircraft and destroy them.
‘The reality was that no Harrier in 1982 did anything of the sort, the air-combat successes being achieved by traditional manoeuvres and the Harrier’s vectored thrust only being used for takeoffs and landings.
‘The problem with VIFFing in combat, is that it’s the sister to Pugachev’s Cobra and the fictional “I’m gonna hit the brakes and he’ll fly right by” of Top Gun: in theory, in a one-on-one turning fight with the enemy behind you, scrubbing off most of your energy “forces the opponent out in front” where you can kill him.
‘Unfortunately, he’s still doing 500 knots and you’ve slowed down to 200 or so – so he’s not only in front, but extending away rapidly, while you’re wallowing and slow: he’s out of guns range in a couple of seconds, and a bad (low-energy, opening fast target) shot for a heatseeker. In Hollywood of course your fighter accelerates back up to full “combat velocity” the moment you “release the brakes” (I half-expected Tom Cruise to say he was ‘locking S-foils in attack position’…) but in reality it takes time to recover all the energy you just threw away – during which the enemy is repositioning with a huge energy advantage and trying to kill you.
‘Worse, this assumes a movie-style one-on-one duel: while your opponent extends away in front of you, his wingman is unable to believe his luck that you’re now a slow, sluggish target that’s dumped three-quarters of its kinetic energy to be a slow, easy target right in front of him (remember, “speed is life”) and his biggest problem with killing you is likely to be a high closing speed. (Where’s your wingman in all this, and is he slowing down in unison as an ACM suicide pact?)’
‘So, while aerodynamically it works, it’s of very limited value in reality and simply isn’t used. I’ve heard of one (count it, one) case where it was tried in an exercise (back in the 1980s with RAF Hawks exercising their emergency air-defence role back in Cold War days): when ‘bounced’, the Harrier slowed sharply, the lead Hawk overshot… and his wingman called a Sidewinder shot on the slow, helpless Harrier, which was scored as a kill.’
Photo credit: DCS