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How Possible is to Attach UMPK Kit to a FAB-1500 and Other Inconsistencies

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Illustrative photo: Su-34 dropping a KAB-1500 bomb / Open source photo
Illustrative photo: Su-34 dropping a KAB-1500 bomb / Open source photo

Turning a FAB-1500 into a glide bomb is a very difficult task because the source material, the bomb namely, has quite a unique design, definitely not supposed to glide

Claims that the russians managed to turn a 1.5-ton FAB-1500 dumb bomb into a guided extended-range weapon is a threat to the Ukrainian armed forces. A weapon that could not even be used at all because russian bombers were afraid to approach air defenses suddenly becomes usable from a standoff distance.

Read more: 1.5-Ton FAB-1500 Became a Guided Glide Bomb with UMPK Kit, russian Sources Claim

In the previous article, we detailed the context and significance of such development, now let's analyze the following aspects:

  • is it possible to apply the UMPK glide bomb kit to a FAB-1500 in general;
  • how come FAB-1500 can have a greater range than UMPK-enhanced FAB-250 and FAB-500;
  • how can a Su-34 take two such bombs at once.

FAB-1500 with UMPK – is it Possible?

First things first, the russian blogger spreading the information claims that UMPK kits, earlier confirmed to be applied to smaller FAB-500, and later to FAB-250 as well, now are also available in a version for FAB-1500-M54. For that, the engineers had to redesign the kit from scratch.

The FAB-1500-M54 is a classic Soviet unguided bomb in a "short" casing with a 675-kg warhead. The concept doesn't facilitate gliding, and its shape instead tries to stabilize the fall so it can touch the ground vertically. Therefore, the first assignment on the way toward a glide bomb was to do something about the aerodynamic properties.

FAB-1500
FAB-1500 / Open source illustrative photo

Next, they would have to create a glider with wings able to withstand a "dumbbell" of 1.5 tons of weight. At the same time, the glider must be compact enough to be carried by an aircraft and have a wing unfolding mechanism.

There is a serious problem known about the UMPK's attached to FAB-250/500: they are unfolded by a spring, and the russians already complained they had to fold the wings by hand, it took a lot of physical power and even led to hospitalization of those who were beside the munition when the retainer failed to hold the fins together. Given the dimensions of FAB-1500, the wings of the glider and, accordingly, the spring mechanism must be significantly larger as well.

UMPK FAB-1500 can be Dropped from a Great Distance

The claim is that the gliding FAB-1500 can fly further than UMPK FAB-250/500, that is at least 60-70 km (35-45 mi).

For comparison, here are the specifications of a similar russian weapon called UPAB-1500V. It was created as a glide bomb from the get-go, it has peculiar X-shaped wings unfolding in a telescopic manner. Even such a specially designed bomb with proper aerodynamics can fly only 40 km when dropped from an altitude of 14 km.

With that in mind, reaching even an 80 km range would be difficult for FAB-1500. Especially with gliding alone without any sort of booster.

UPAB-1500V
UPAB-1500V with wings folded (above) and deployed (below) / Open source photos

Another russian project named Grom-E1, essentially a hybrid of a cruise missile and a glide bomb, can attack in a declared range of 120 km. This development is based on the Kh-38 missile and has a weight of 594 kg. Such range is achieved under the conditions of a high-speed drop from an aircraft moving at 1,600 km/h from an altitude 12 km, plus Grom-E1's own rocket engine working.

On the other hand, we can never rule out that the russians went all-out and made monstrously huge wings to help the FAB-1500 bomb fly.

Grom-E1
Grom-E1 was even used against Ukraine at least once / Open source archive photo from a military exhibition in russia

Su-34 Can Take Two UMPK FAB-1500s at Once

The carrier for the enhanced FAB-1500 is said to be the Su-34 tactical bomber aircraft. Indeed, 1,500 kg bombs are officially part of its arsenal. They are attached to pylons inside the weapons bay or to the central one under the fuselage. At least that's where KAB-1500 are usually placed.

On the other hand, an FAB-1500 improved with UMPK might have a weight of 2 tons or beyond, although the biggest problem here would be the size of the winged bomb and its reforged nose cone.

russian Su-34 dropping a KAB-1500 free-fall bomb
russian Su-34 dropping a KAB-1500 free-fall bomb in Syria / Open source archive photo

In summary, answering the question of whether russians technically could create a kit turning an FAB-1500 into a glide bomb – yes, in theory. Would such a product be a reliable weapon? – Likely not.

Either way, the fact russians search for new ways to apply air-launched weapons is a dangerous trend and even unreliable or poorly executed FAB-1500 would be a threat if they start falling on Ukrainian positions. That is why Ukraine, on the other hand, needs proper air defense assets to restrict the area that russian aircraft can enter without coming in range of Ukraine's medium-range anti-aircraft weapons.

Read more: How Many Aircraft Does russia Have to Launch Glide Bombs, Spoiler: Not Too Many