By Tommy H. Thomason

Tuesday, April 23, 2013

Things Under Wings: FJ-4B

23 April 2013 Revision: Well, that didn't take long. Gerry Whiteside has correctly identified the weapon on the FJ-4B in this post as a 750-lb Mk 77 Fire Bomb modified with a Mk 19 Bomb Conversion Kit. I've revised the post accordingly...

I'm just knowledgeable enough to know that these are not standard bombs under the wing of  a VA-63 FJ-4B:
Emil Buehler Library, National Museum of Naval Aviation

My go-to guy for stuff like this, Jim Rotramel, confirmed that it was definitely not a 2,000-lb bomb as a caption in at least one publication would have it but did not know what it was.

And there is a second picture of one being jettisoned from a different VA-63 FJ-4B:

Emil Buehler Library, National Museum of Naval Aviation

What was somewhat mystifying at first is that this is a squadron airplane, not a North American dog ship or a VX-5 FJ-4B that would usually be used stores-jettison envelope tests, one of the more dangerous flight test events (the store might depart cleanly or it might go rogue, with dire consequences).

But wait, there's more: the photo caption for the first picture indicates that it was taken on 9 September 1958, shortly after the squadron had begun a deployment aboard Midway (CVA-41). A stores-carry and jettison evaluation by a squadron at sea? That seems unusual even though those were somewhat more permissive times in Naval Aviation.

Close examination of the store suggested that it might be an AJ Savage tip tank with the addition of a tail fin kludge (for one thing, the fins are externally braced).

Note the clear nose and that they might be painted sea blue. The FJ-4B store seemed a bit longer than the AJ tank but that could have been a modification, like the addition of the shackles and fins. (The FJ-1 Fury carried a similar tip tank and an longer version was used to provide the range, just barely, for the Bendix Trophy "Race"  in 1948.)
As a result, I had thought that it might have been a kludge to provide a source of external fuel tanks because not enough of the unique FJ-4 drop tanks were available for this deployment, one of the first for the FJ-4B.

Another guess was that it was a revisit to a home-grown napalm bomb concept to have on hand for crowd control if necessary. That turned out to be close. As Gerry pointed out in his comment below, it is actually a standard 750-lb Mk 77 fire bomb with the Mk 19 bomb conversion kit. It does in fact have a clear nose cone over the igniter. The addition of tail fins in the bomb kit allowed it to be dropped from a dive as opposed to a low-level pass.


Anonymous said...


Those bombs are 750 lb Mk 77 Mod 0 with a Mk 19 Mod 0 Bomb Conversion Kit.

They are 750 lb fire bombs

This can be found on page 10-34 in the OP 2216 (Vol I) dated 1 Aug 1960.

G. Whiteside

Tailspin said...

Thanks very much - I don't think I've ever seen it before...

Jim Doran said...

I've loaded a few of these on A-1H/J Skyraiders aboard USS Ticonderoga during Vietnam War "Start Up" (Aug 64). They were easy to load - we'd load them empty, put in the proper amount of Aluminum Stearate (4% by weight) and then fill the bomb with Avgas
(115/145 Octane) stir it up with a swab handle and install the igniter. Never did use the fins though.
Jim Doran
Chief Aviation Ordnance Technician (W-4), USN (Ret)