I had figured it was perhaps a weird characteristic of the simulation's breakdown of airframe components, but if that's how things worked in the real F-4's, that just gives me that much more respect for the physics simulation in X-Plane. No wonder it's FAA certified :)
BRYSON, A.E. and DENHAM, W.F., "A steepest-ascent method for solving optimum programming problems," Trans. ASME. J. Appl. Mechanics, June 1962, pp. 247-257.
I can't find a PDF copy anywhere. It sucks. If you want to read a non-technical paper on it, try this one: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=00506395
You can use the pop-up maneuver then. You fly low and fast to avoid radar detection and AAA fire. When you get close to the target you climb at 45 degrees, roll 180 degrees (you are now flying inverted), prepare the JDAM's to be deployed. You then pitch up and when you are at the top of a parabolic flight path, you release the JDAM's. The inertia build-up during the ascent will make the bombs go faster and farther. Once the bombs are deployed, you fly low again.
There are some technical papers on this. It's heavy math: optimizing flight paths is not exactly a trivial problem ;-)
BTW - There is a book written about the history of the Mirage in the SAAF called 'vlamgat' (lit. fire/fiery - behind/ass). Try http://www.saairforce.co.za/reviews/33/vlamgat-cd.
Anyway. In this book, which is written by an ex-pilot, a maneuver is described which sounds very similar to the pop-up. The aircraft also approaches the target at low altitude, then pitches up. As the pilots pull up on the stick they release their bombs, but continue climbing up and away. The bombs (old fashioned, dumb bombs) would then fly in a parabolic trajectory like you'd expect and land somewhere near the target ;)
If I remember correctly this tactic was actually used in combat with surprisingly effective results. I say surprising because nobody believed you could actually hit a target with a bomb that flies in a trajectory with a horizontal length of a few 100 to 1000 meters and was released on the pilot's 'gut' feeling...
It reminds me of that classical optimal control problem in the 1960s: the U.S. Air Force wanted to find the fastest climb for its F-4 Phantoms (so they could reach their operational ceiling ASAP to intercept Soviet bombers). The optimal path was counter-intuitive: first climb, then dive, reach supersonic, climb again. Sounds crazy, but they could reduce the climbing time dramatically that way!