What is “bulbous Neptune” and why does it have mid-body bulges?

During a demonstration of the capabilities of Ukraine’s defense-industrial complex for NATO member representatives, a version of the Neptune cruise missile that had never before been mentioned was publicly shown, Defense Express reports.

In one of the photos posted by Ukraine’s Minister of Defense, Denys Shmyhal, the R-360 missile appears with unusual mid-body bulges. Because there is no known index for this variant and given the reaction on social media, it can for now be called the “bulbous Neptune.”

It differs from the two known versions — the anti-ship R-360 and the extended-range RK360L, known as the Long Neptune (the more likely index is R-360L).

"Unfortunately, the photo angle makes it impossible to precisely compare all three variants. However, it is worth noting that the diameter of the “bulbous Neptune” matches the anti-ship version (38 cm), as likely do the wing span and overall length (about 4.5 m without the booster)," Defense Express experts said.

"The bulges are, with high probability, conformal fuel tanks that increase the missile’s flight range. Recall that the R-360’s declared range is 280 km, while the Long Neptune is said to reach 1,000 km.

Given conventional classes of target ranges, a logical assumption is that the “bulbous Neptune” would have an approximate range of 500 km," military analysts added. 

At the same time, there is always the possibility that designers traded fuel (and range) for a larger warhead. 

"Thus, we should not dismiss a variant with a conditional range of about 300 km but a warhead heavier than the R-360’s ~150 kg. For context, the Long Neptune has a declared warhead of 260 kg," Defense Express summed up.

Overall, showing the Neptune missile to European partners is highly significant for attracting investment in missile production. The Long Neptune, in particular, has reportedly outperformed the MdCN — the only long-range cruise missile developed in Europe.