‘VIFF stood for “vectoring thrust in launch forward flight” and entailed rotating the variable angle jet nozzles mounted to the sides of the fuselage downward,’ Doug Dildy, former F-15 pilot.
Since during the Cold War the mission of the F-15 and the men (and now women) who flew it was (and actually still is) air superiority — the efficient, remorseless killing of any aircraft that dared stand in their way — Eagle Drivers took great pains to know their potential foes very well, to learn their weaknesses, know how to combat them, and how to survive and live to fight another one.
In doing so, the variety of Western fighters provided some basis for emphasizing certain maneuvers and engagement techniques that could be used against Soviet (or other foreign) equipment that had similar capabilities.
‘The RAF (Royal Air Force) Harrier pilots prided themselves on their VIFFing defensive maneuver,’ former F-15 pilot Doug Dildy explains in his and Steve Davies’ book F-15 Eagle Engaged. ‘VIFF stood for “vectoring thrust in launch forward flight” and entailed rotating the variable angle jet nozzles mounted to the sides of the fuselage downward. This would substantially increase the nose (turning) rate of the little “jump jet” for an instant, but we’re getting ahead of ourselves.
‘The RAF Harrier GR.Mk 3s were tremendous ground attack jets and the FAA (Fleet Air Arm) Sea Harriers did an admirable and highly respected job against the Argentines in the Falklands conflict. The GR.Mk 3 lacked radar so it was a visual-only fighter employing the AIM-9L with a fixed (called an “iron” sight). Nevertheless, for DACT we would begin BVR so they could practice defeating radar missiles (we wouldn’t call them “dead” on AIM-7 shots), and when we arrived at the merge we were more or less equal since both of us were “slinging Limas” (I’m being kind now, actually they were never equal to us).
‘The Harriers invariably took the “low block” of altitudes since their engine performance was better where the air was thicker (they had no afterburners). This preference resulted in the Harrier’s high-mounted wing masking its hot exhausts and while the Harrier pilot rarely spotted us arriving at the merge in time to shoot an AIM-9L, we were usually denied a pre-merge AIM-9L kill because of the wing/exhaust arrangement. Immediately a turning fight would ensue with the Eagle using its power and turn capabilities to twist in the vertical, pirouette and descend into the guns envelope.’
Dildy continues:
‘As the Harrier Driver saw the Eagle swooping down, he would carefully time his VIFFing maneuver to rotate the GR.Mk 3 broadside in front of the F-15. The sudden loss of thrust from rotating the nozzles downward also acted as a powerful speedbrake and the Harrier seemed to stop in space. If – and this is a big if – the Eagle Driver was not paying attention, hadn’t done his homework, or “had his fangs out” going for the kill, an embarrassing overshoot could result. As the Eagle zoomed by, the Harrier would tuck the nozzles in, put the “iron sight” on the glowing F100 afterburners and shoot a Lima up his tailpipes.
‘Far more often the sudden rotation of the Harrier in front of us and the appearing to come to a complete stop in the air was warning enough that there was some VIFFing going on. In this case, the Eagle Driver simply went to idle and pulled on the pole to exchange knots for altitude and zoom up and out of the Harrier’s WEZ. Rolling over on our backs, we’d chuckle to ourselves as we began to compute the trajectory needed to return to guns parameters. He was now out of knots and “dead in the water.”
‘This is because airflow over the wings is what generates lift at 10,000 feet, and after VIFFing the Harrier had none. The vectored thrust at that altitude (since thrust coming out the exhaust is proportional to the air being gulped in the front; no knots: no air) was only a fraction of the weight of the aircraft and consequently the Harrier would have to roll off to one side, put its nose down and begin accelerating again as it descended to the floor of the DACT airspace. Tipping its tail up to dive, it frequently offered an attractive heat source to the AIM-9L’s seeker head since now the wings no longer provided a cover over the exhausts – “Fox Two kill the Harrier diving through 7,000 feet.”’
Dildy concludes:
‘Because of supposed similarities with the Soviet Navy’s Yak-36 “Forger” carrier-borne fighter, fighting the Harrier was more than just “fun over the Mediterranean.”’
F-15 Eagle engaged is published by Osprey Publishing and is available to order here.
Photo credit: U.S. Air Force and Crown Copyright
