Russia's 'Father Of All Bombs' is a much more sophisticated weapon than it might appear. The eight-ton bomb is equivalent to more than five times its own weight in TNT, more than has been claimed for any equivalent Western device. This is an area in which Russia has been leading for many years, and as I have previously mentioned,US efforts have been mainly a matter of playing catch up.
With a fuel-air explosive, it is critical that the cloud of fuel mixes as efficiently as possible with the air. Uneven mixing will not produce an effective blast. And the fuel has to burn completely, which requires very small, evenly-sized particles. The technical challenge is greater the bigger the device involved, and the Russians seem to have found ways of tackling this at the very largest scale.
By contrast, a 2004 National Academy report on US thermobaric developments is highly critical. The BLU-118 'cave buster' used in Afghanistan, which was hailed at the time as a feat of rapid development, comes in for particular citicism. The report states that these efforts were largely driven by intelligence and 'efforts to exploit foreign technology'.
Note that the explosive mentioned critically, IH-135 or PBXIH-135, is still used in the latest US thermobaric weapons like the shoulder-launched SMAW-NE. (One might also note the irony that this weapon only acquired the dreaded 'thermobaric' tag and media infamy because the military redefined it as such).
To many people it may be heresy to suggest that another nation might be more advanced than the US in any area of technology, military or otherwise. But sometimes national pride needs to take a back seat when there is learning to be done.
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