You can build a floating floodgate under a hatch and link both up to the same trigger. The vamp will drop his stuff when the hatch opens, but neither he nor the item will fall until the floodgate opens, which I think has the 100 delay.
That's a cool idea, that I'm going to try to use for something, but I'd rather avoid it for this-- the idea is that an extra 100 ticks gives the vampire extra time to reach his drop destination, and if the hatch opens before then, then he won't make it onto the drop square in time. (If you were to build a hydromechanical delay for the hatch, why not just use a fully hydromechanical system?)
Considering that vampires are pretty damn robust constitutionally, is there even a need to cushion them? I would think that a super-tough vampire would survive a brief fall.
Definitely a need. The big delay for further testing has been that I've had an injured vamp at the bottom of a drop chute for several seasons. I've been waiting for him to get better, not wanting to bring him to my hospital and risk his thirst. I'm just now building a second drop chute for testing purposes, tired of waiting on his broken limbs.
How are you measuring ticks?
I pause the game and advance with the . key. I use additional doors to make sure that I know exactly when signals are received. When I say it takes 7 ticks for a dwarf to fall his first z-level, what I mean is that at 0, the hatch opens (as well as a nearby door); from 0-6, the dwarf hasn't fallen; and at 7, the dwarf is at the next z-level.
By the way, for anyone interested, I have a good hypothesis about why the first z-level takes an extra tick. The game evaluates dwarves (maybe all creatures), then objects, in series. What happens in tick 0 is that the dwarf is evaluated for falling BEFORE the hatch is opened, although both happen on that tick. Because the dwarf is evaluated first, he doesn't fall, because the hatch doesn't open until later in that same tick. Does that make sense?
Is the vampire taking injuries from his falls? if so, is he healing?
The goal here is a consistent delay that can be used for a clock.
Any damage is unacceptable for my purposes.
Bridges. Due to bridges seeming to fling objects in random directions, random distances, this is probably bad compared to retracting hatches/grates/bars.
They're fine, because the dwarf is constrained to a single square at time of drop-- there's no place to get flung to.
Put the pressure plate at the bottom of a column of water, like so. In theory, any creature can fall from this and hit the ground stunned. A good swimmer or a vampire will walk out unharmed. Lesser creatures may drown, but should still trigger the plate.
I doubt that it's even necessary to depressurize it; in fact, submersion is a good method to get the vampire to return near reset position before it's even accessible, as they seem to walk in water to dry land, rather than spazzing out like regular, oxygen-dependent dwarves do. Is that a surefire protection against damage? I'll certainly add that to the testing queue (which, sorry, is going slow, kind of burning out on 34.x). If it's surefire protection, and speed of falling through water remains constant, then it's probably better than the creature cushion for most purposes.