Joseph S. Wisniewski wrote:
The big problem is that the AD-26 is a pretty limited AC adapter. A speedlight needs about 100-120 w-s to charge. It's only a 60-80 w-s device, but it's charging circuitry seems to only be 50-70% efficient. NiMH batteries can deliver up 30W with no trouble and charge a flash in 4-5 seconds. The AC-26 is more like 10W.
But the 555 has a 320V high voltage input. Theoretically, all you need between the VML and the 555 is a bridge rectifier, and you should be able to get 1-2 second recycle times. As far as putting that theory into practice, well, not on my watch. I would suggest not trying to perform that experiment.
Joseph . . . you're a smart guy and I alway enjoy your posts. Want a job:)
You're dead on with this one . . . a 230V VML plus bridge rectifier would give you 324V via a speedlight hi voltage input . . . perfect. My first thought was (thinking in terms of the connecting a rectifier to a 230V powerline) was it would charge the flashcap instantly . . . which ain't good . . . big bang! But the 230VVML is current limited to about 250Watts. 
Gee . . . . 250W into a 60WS flash cap would charge it in 1/4 second. . . about the same rate as a 160WS B400 at 1/2 power plugged into the wall. That's a match made in heaven . . . safe, won't stress anything and around 5000 60WS pops per battery charge. Sounds like the ultimate speed cycler. May have to think about that VML use. As you say, it just takes a $1 rectifier and appropriate cable.
One possible caveat that would require a bit of testing: With conventional studio flash design there is a situation known as afterglow. When a flashtube discharges and an immediate high current recharges the caps the tube can remain in conduction. I don't believe this can happen in an IGBT speedlight because the IGBT interrupts the current with each shot. In our lights we have afterglow prevention circuitry. But if this were to occur, the speedlight would sit there glowing and become a continuous 250W light. This would fry the tube in a couple of seconds. So if you try this, make sure you put a switch inline with the charging current so you can quickly shut it off if anything like this happens.