thedeathofall wrote:I didn't even have the correct drag coefficient typed in.
So how could you even expect it was going to give you the right figure?
I don't want to kill anyone on the field if this thing misfires.
On the note of definitions again, no-one should be harmed as the result of a misfire. Misfiring is failure to fire, not unintentional* firing.
*I prefer not to say accidental, because that implies there's nobody to blame.
Firing unintentionally is known as "Being a total plank."
Of course, why it misfires might be a different matter. If it's some part failing explosively, that might well cause injury.
POLAND_SPUD wrote:check the data you've entered into GGDT... AFAIK 0.5oz is rougly 28g.. I doubt that the piston is so heavy as the one on my 'european' 1/2" QEV is less than 5g
A whole ounce is 28 grams. Half an ounce will be ... I'm sure you can work that one out.
most guys model QEVs as generic valves with 5ms opening time and dwell time of 1000...
Not actually true, as far as I know. I certainly don't model them as Generic valves, I model them as barrel sealers, because... well, that's what they are, in all but name.
Also, they open in closer to 1 or 2 ms, not 5 ms.
also 60% for flow coef seems too optimistic as 65% is the max flow you can get (enter something like 45%)
Partly true. 60% is optimistic, and 45% is more typical for a QEV.
65% is however not the maximum you can get. By definition, the flow coefficient is the orifice's flow divided by the maximum possible flow possible for the orifice size.
65% is therefore 65% of the maximum possible. 65% is what happens when hard edges exist in the flow. In other circumstances, efficiencies of approaching, or even theoretically a full 100% are achievable.
also I suspect that a nerf dart has a better cd value than 0.5... (ask btrettel IIRC he has done some research)
It will do. Unfortunately, I don't have it listed anywhere, nor have I the data I would need to calculate it, so I can't tell you what it is.
There are lots of things I could tell you, but Nerf vortexes are not among them.
However, I do need to find out myself, because I have no doubt that when I'm done with the LRC (and yes, I am still working on it, and getting close), people will start asking me.
So, at some point, I'll need to enlist the help of patient people with chronographs to start determining some of the Cd values I don't know.
Also, I should point out before you bother him, Btrettel's research is on nerf darts (homemade ones, I believe), not this form of thing.