The Grumman A-6 Intruder and the Original Plans to Incorporate Vectored Thrust

The first seven Intruders had vectored thrust, but in practice during flight testing, the performance benefit was marginal at best.

The US Marine Corps had initially required the Grumman A-6 Intruder to meet an STOL requirement to take off in 1500 feet over a 50 foot obstacle. To accomplish this, the first seven A-6 Intruders (prior to 1962 the Intruder was designated A2F) had tilting tailpipes in which the exhaust of the twin J52 engines was vectored downward 23 degrees on takeoff and landing. There was a knurled knob on the outboard throttle that the pilot used to activate the feature.

This vectored thrust feature was one of the reasons that the Intruder had such a distinctive tadpole-shaped fuselage.

During flight testing, it was shown that it only made a difference at light weights and was of negligible benefit at more typical combat weights.

The feature was deleted at a cost savings of $25,000 per aircraft. After some back and forth arguing between the Marines and the Navy, the tailpipes and the associated actuation mechanisms were deleted beginning with aircraft number 8. Only the seven pre-production Intruders had the feature.

The idea resurfaced briefly in 1979 as concerns about being able to bring back aboard the carrier unexpended precision guided weapons from combat missions. Square section tailpipes with deflector flaps were considered but again, cost and complexity put an end to the concept.