Cold War Era

No Internal Gun and Smoking Engines: former Topgun pilots explain why US Navy F-4s initially struggled to compete with North Vietnamese MiG-17 and MiG-21 fighters

Despite flying the world’s most modern fighter interceptor armed with state-of-the-art AIM-7 and AIM-9 guided missiles, US Navy F-4 crews initially struggled to compete with their North Vietnamese counterparts.


Despite flying the world’s most modern fighter interceptor armed with state-of-the-art AIM-7 and AIM-9 guided missiles, US Navy F-4 crews initially struggled to compete with their North Vietnamese counterparts, who were far less experienced, and equipped with inferior types such as the MiG-17 and MiG-21.

In fact, as explained by Brad Elward and Peter E Davies in their book US Navy F-4 Phantom II MiG Killers 1965–70, even with its armada of advanced and continually updated missiles, the Phantom II was lacking in one critical respect — it carried no internal gun. Although crews tried to remedy this serious oversight by adding a centreline gun pod (the SUU-23, housing the M61 Vulcan 20 mm six-barrelled Gatling gun fitted in the self-powered GAU-4 unit), it proved unworkable and was abandoned. With the pod fitted, the ubiquitous `fixture’ centreline drop tank had to be abandoned, resulting in two smaller tanks taking up vital space on the outer wing pylons. And the overall unreliability of the gun pod was further exacerbated by the shock of deck launches and recoveries. Despite these problems, a similar system enjoyed some success, and wider employment, with the USAF and Marines.

F-4 veteran and former Topgun instructor John Nash explained to Elward and Davies that the failure to include an internal gun was ‘a tragic mistake’;

`The F-4 needed an internal gun. The USAF had the better F-4 in the E-model (which had an internal gun). The Navy bought the Mk 4 (GAU-4) gun pod, which was “worthless”, and that is an understatement. The NAVAIR civilians forbade us to go to Nellis and get 40 USAF SUU-16 gun pods for free when I was in VF-121/Topgun.

`Having an internal gun would have given the aircrews one more kill option. But as important as that, it would have changed the enemy’s tactics. A gun would have added a significant threat that would have had to have been defended against by the MiGs. As it was, in an air-to-air engagement, a US Navy F-4 at 500 ft behind a bogie was totally ineffective without a gun.’

This print is available in multiple sizes from – CLICK HERE TO GET YOURS. F-4J Phantom II VF-96 Fighting Falcons, NG100 / 155800 / 1972 – “Showtime 100”

Although configurations were often mission-driven, F-4Bs could launch with up to four AIM-7 and four AIM-9 missiles and a 600-US gallon (2270 I) centreline tank. Odd configurations, such as six Sparrows, were sometimes carried, as were 370-US gallon (1400 l) wing-mounted tanks. F-4s flying BARrier Combat Air Patrols (BARCAP) were often configured with three AIM-9s, two AIM-7s and a centreline tank, whilst Phantom IIs flying MiGCAP (hunting for MiGs) typically boasted four AIM-9s and four AIM-7s, with between one and three external tanks.

The F-4B relied on two 17,000-lb (75.65-kN) maximum afterburner rated General Electric J79-GE-8 turbojet engines to power it off the carrier deck, with the assistance of the catapult. Although basically a good engine, the J79’s primary drawback was that it left a long, black smoke trail when not operating in afterburner. This meant that Phantom IIs could be seen from many miles away, sometimes as far as 25 miles. `Smoking engines get you shot, or shot at’, noted John Nash.

MiG pilots used this deficiency to their advantage on many occasions during the Rolling Thunder campaign, conducting sneak attacks on F-4 formations. The problem was finally rectified in later models of the F-4J (from Block 37 onwards), and retrofitted into early Js and F-4Bs. However, some squadrons soldiered on with ‘smoking’ Phantom IIs until war’s end, as John Nash explains;

`We had an “additive rank” that could inject something into the engine that was supposed to stop the smoking. However, I never saw any of the “stuff”, and no one was concerned enough to get the programme going! Min-burner stopped the smoke trails, but burned gas faster – not the ideal remedy, but when no one cares enough to fix the problem, that’s the only solution.’

Crews were wise to this problem, and devised several of their own ingenious ‘fix-alls’, including flying in minimum afterburner, then quickly changing altitude, and flying with one engine in idle and the second in minimum burner. Capt Jim Ruliffson, a former F-4 pilot and commanding officer of Topgun, also commented on these tactics;

‘We trained in the States to go min-burner, which eliminated the smoke completely, when setting up head-on engagements. Over North Vietnam, though, we rarely had the “luxury” of knowing there was a bogie nearby, let alone in a position for a classic head-on pass, so nobody went min-burner to eliminate smoke trails.’

Yet, despite these serious problems, and handicapped by strict rules of engagement that effectively nullified any tactical advantage gained by having weapons that could hit targets beyond visual range, Phantom II crews prevailed. Less than ten naval aircraft were downed by MiGs in the first five years of the war, thus proving that the fighter crews had indeed done their job; at least 15 Vietnamese aircraft were destroyed by Navy F-4 crews during that time.

US Navy F-4 Phantom II MiG Killers 1965–70 is published by Osprey Publishing and is available to order here.

Photo credit: U.S. Navy; Top image: unknown via

This model is available AirModels – CLICK HERE TO GET YOURS.
Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

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