What drills, and techniques work to crank those things up to 11? What tone should be aimed for max projection, etc.
Personally, I found that I couldn’t play a loud note well unless I could also rein it in down to a wispier.
Robert Dick describes two approaches to learning how one sounds from a distance: the techie approach uses headphones and a microphone placed far away from the player; the more ‘natural’ approach involves playing in the great outdoors. http://www.larrykrantz.com/rdick2.htm#hearself
Just to preface that I count projection, volume, and audibility as three different things, yet parts of a whole. Projection is an inherent quality of flutes in general; volume is simply volume; audibility is how other hear you. Volume may assist projection and audibility, but it isn’t always a requirement.
One thing I’ve found over time is that, paradoxically, the harder I try the less sure my volume/audibility is. Control gets lost, things go awry, and others find it hard to hear exactly what notes you’re playing especially in a noisy situation. In trying hard, there’s a tendency to tighten up the whole embouchure and think in terms of “blowing”, as from the mouth. Instead, keeping just the corners of the mouth firm, try for a relaxed feeling where the air stream itself comes out. Let the upper lip slightly form a hood over the embouchure hole. And rather than blowing, think of breathing out, from down in the belly and up through an open throat.
Made a big difference for me, anyway.
If I’m getting your drift, wouldn’t how the note gets played change projection? Seems to me there are the “blow into/blow across” camps looking for that “dirty/pure” sound.
Could be, but how or why, I wouldn’t know. I’m actually not wholly convinced of it. I’ve heard even poorly played flutes project, so I’m still of the opinion that projection is a fundamentally inherent quality of the instrument. That’s why I said, “Volume may assist projection and audibility, but it isn’t always a requirement.” Skilled embouchure - however you do it - no doubt increases the presence - which I count as an aspect of audibility - of what is projected. I would hazard a guess that what you do with your mouth has less influence on projection distance than does the construction of the flute body itself. That said, I do believe that projection IS in part influenced by the player. Whether that influence actually means a better player will project further, is something I’d have to pay more attention to; it’s not a factor that’s ever stood out to me, to be honest; if it had stood out, I’m pretty sure I would have noticed it. To me any differences are more an issue of presence than anything else.
In fine weather when the pub’s doors are open, when I approach to the point where I can hear the flutes, I pretty much hear them all. It’s the presence of each that isn’t necessarily equal.
Personally, I wouldn’t focus on projection so much, as testing it would be cumbersomely awkward and anyway you would be dealing with subjective hearing to tell you how you’re doing. Your flute is going to project without your even making a point of it. Easier (and better, IMO) to focus on good tone, consistency, volume, and how you combine them. Anyway, that’s my two cents worth.
Here’s a reinforcement of my assertion that projection is already built into the instrument:
At an outdoor gig yesterday, the distance from my car in the parking lot to where we were playing was around 200 yards I think, and partly occluded by buildings. At the spot appointed one of my bandmates was idling about on his flute, unamplified and not particularly loudly; yet from my car’s location I was able to hear it clear as day, and almost (not really quite, but almost) seemingly as present to my ear as if I had been right there, separated from him by only one other chair and the spaces in between. It’s not his primary instrument; while serviceable enough, the flute was no top-end job; and he’ll be the first to say he’s not a strong player. I was a bit astonished at the experience.
I suppose I could have gone the other direction to find at what point I could no longer hear the flute - the thought had occurred to me - but that was looking like it would be a distance greater than I was willing to trudge, and anyway time was not on my side for such rambles. I figured good audibility at 200 yards - unamplified and at no great force otherwise, mind you - was pretty respectable.
I play a lot outdoors while hiking and notice tremendous variability in different locations, in terms of how far/strongly the flute projects, as well as how loud it sounds to me while playing. It really seems unpredictable to me - sometimes I can barely hear myself, and to my surprise people will tell me it’s very loud hundreds of yards away… and vice-versa. And these are wide open areas, not canyons, etc. - Tod
There was an earlier discussion about hearing flutes and whistle well at a distance. IIRC one line of argument was that because a flute puts a lot of energy into the fundamental frequency that frequency might, at a distance, get above a wide spectrum of background noise whereas another instrument (fiddle maybe) that spreads energy into higher harmonics may not be far enough above background at any particular frequency for the ear to pick it out. Something like that anyway.
So IOW it might have been the luck of the draw for me. Fair enough. 
Still, my usual experience has been one of projection.
When I’m playing solo for dancers I prefer to go Eb over D. I have this idea that it “cuts through” the battering better. How much better I couldn’t say, but it does seem to be the case.
Of course it could be all about the construction proportions, too; an Eb body additional to a D body flute is going to have a proportionally “wider” bore, ratio-wise.