I fully understand that a parachute will move with the wind. My speculation is that in a wind the angle of attack of the chute is not 0, and the chute might generate some lift and move into the apparent wind. <snip>
There is no "apparent wind" as far as the parachute canopy is concerned. There is only motion relative to the ground - of which the parachute has zero 'knowledge' of. That motion is simply a function of descent rate and the velocity of the air mass the parachute is descending in. If the air mass was moving at 50mph *relative to the ground* or was dead calm, the parachute sees the same thing: zero velocity.
[edit & expansion]
I want to elaborate a little on this aspect of this discussion and put my own reasoning out here - in hopes of helping those (not necessarily yourself, Bob) who find some aspects of this bizarre (as it surely can be): To be sure, it is counter-intuitive to say, "Parachutes don't drift - the air mass just moves" (as we're almost saying). Look at it this way: if the parachute/payload 'drifts' (i.e. has a velocity relative to the ground) LESS (by even the slightest amount) than the velocity of the air mass, then there must be some 'force input' to retard that motion relative to the air mass. OK, so what is it? (is it dragging some kind of 'anchor' or something?) There isn't any. If it 'drifts' at a rate GREATER than the velocity of the air mass, there is some other 'force input' to provide that additional velocity. OK, so what is *that*? Again, there isn't any. (gliding behavior discussed in a moment). The only 'equilibrium state' for this canopy descending in a moving air mass is exactly in accord with that air mass's velocity - otherwise, one has to explain where that 'delta V' is coming from.
Gliding? OK, sure, canopies can 'glide' (most particularly the cellular canopies), but even circular canopies can show that tendency (the Para-Commander particularly comes to mind). Will this increase (or decrease) drift? Unlikely, as (again) the canopy has *zero* knowledge that the air mass is moving in any particular direction at any particular velocity (how could it possibly know which direction is 'downwind'?) Thus, 'gliding' is entirely in a random direction and whatever portion is 'downwind' will cancel with whatever portion is 'upwind' -- net result: no change in distance covered *relative to the ground*. IF there was any gliding, I just can't see that the final touchdown point would change one iota from the exact same descent with a non-gliding canopy.
One way to help visualize the canopy in relation to the air mass it is in would be to tie on a 20 (or 50) foot piece of surveyor's flagging tape to the rocket -- to be ejected with the main canopy. Disregarding the smallish fluttering (from the actual descent velocity), I would venture to posit that the tape would hang straight down (and, no, I haven't tried it). Maybe this would graphically illustrate the situation this discussion is dealing with.
Back on topic ---- as far as the canopies I've made (see other threads), I've generally always used from 0.5% to 1% of the canopy AREA for my spill holes --- heavily leaning to the 1% figure (i.e. 10% of the canopy diameter (and, yes, I would call it "nominal diameter" Do)).
[end edit]
-- john.