If I understand, you want to drill a 3/16" diameter hole through 16" of wood?  What is the wood?  Is the wood straight grain, crotch, burl, . . .?  If straight grain, are you wanting to drill with the grain, diagonal to it, or perpendicular to it?  Has the wood already been on the lathe and if so what has been done with it?  What kinds of lathe and turning experience do you have?  What is the maximum distance between the headstock and tailstock?  Is your tailstock hollow?  What type of live center do you have in your tailstock?  Sorry for all the questions but more information would be helpful.

Google boring a hole in wood with a gun drill. Especially "Native American flute boring with a gun drill".

Drilling a 3/16" through hole in a 16" long billet of African Blackwood is almost impossible. The difficulty is in keeping the hole straight and/or the drill bit running true.
This is another situation where you may need to drill from each end and try to meet in the center,
OR
Split the billet, route a semicircular groove in each half and glue the halves back together.
Also a 3/16" bit is very thin, prone to wandering and are going to be difficult/expensive to find longer than 12".
Here is some information on African Blackwood.
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I don't know what a D bit is, but if you are to do this, a gun bit is the way to go.

Your biggest issue, no matter what you use is that your lathe bed is not long enough to do the job. You have a lathe with an 18" bed. You want to drill a 16" billet. So, your bit needs to be at least 16" long. When you add the length of the billet to the length of the bit, you need a lathe bed longer than 32". In fact, when you add the length of the drill chuck holding the bit, you need even more length.  (You've said that your tailstock is not hollow, so the option of gradually feeding the bit through the tailstock is not available to you.)

In reference to your comment about people doing this for some time, I wonder if what they are doing is drilling a square profile blank, then holding the blank in the lathe with centers in both the headstock and the tailstock. Doing this, then rounding the blank allows the turner to "center" the hole in the blank, where it has wandered during drilling. I've done this on shorter pieces for pepper grinder.

If the wood turns and the drill is held still it usually goes straight.  I would turn between centers first to get a cylinder if that is acceptable and then chuck on that.  16 inches is a long way to protrude from a chuck.  A drive spur and or some type of drive dog and letting the tail end rid on the bit might work best.  you might make a tail guide for the drill or use a tailstock with a through hole and bushing to feed the bit through and hold and feed the bit by hand.  The bid issue is clearance for the chips.  The smaller the drill the worse the problem.  You need to withdraw the bit completely and clear the chips every half inch or so of drilling.  Hence the bit through a bushing from the tailstock and push it in and out by hand,   I have brazed drills onto rods to get a longer bit to work with.  It needs to be fairly straight, but not perfect since the drill is not turning.  I have never tried it without the tailstock or guide but I can see how that might work with a mid sized drill.  Just let it ride on the drill.  The problem with using a chuck with a long outing is that if there is any misalignment (wobble) the tail stock will hand against that and work the material loose in the chuck.  Something to keep a close eye on.  Most of my drilling disasters have been from not keeping the chips clear or from drilling too small a diameter piece and exploding it from either the chips or the cutting force.

There are many ways to go about making a Uilleann pipe chanter
Some have tapered bores
Some have a brass tube inserted
This is a specialized craft.

While I have a lathe long enough for such a task, I would bore this hole on a drill press, where gravity is not working against me. Starting with a standard or even short bit to avoid flexing. 3/16" (4.7mm) is not very big at all and can easily bend with just a small amount of excess pressure. Then proceed to the next longer bit and so on. Keeping less of the bit free and more of the shank supported buy the bore will help support the bit should it want to flex. (I wouldn't start with a 16" long bit) After drilling, mount on lathes between cone centers and true the blank to the bore.

Long hole boring really isn't a big deal but when working with such a small diameter bit/bore there are more things to consider.

ok, I guess it's my turn..
Funny, we've actually not spent any time talking about the thread topic!
lol... that's ok I bought a chuck.

A couple things:
I misspoke about the tailstock: it IS hollow
I do appreciate Ed, and all you fine folk.
I was honestly awaiting some feedback from a couple of people regarding the issue at hand, so I could lend a little support to the idea. (still waiting)

What I'm envisioning is:(more or less)
Mounting the blank, turning a tenon, remounting & then turning the whoe blank round.
Then removing tailstock, and substituting a steady rest.
Then....slowly feeding a D bit in(having created my shallow & centered guide hole) and removing OFTEN & cooling the bit(not with water).
Unsure right now, if I'd be able to utilise the tailstock, as I'm guessing the piece might be too long:I really need to look more closely at my plans.

This could be an epic flop, I could wind up with the thing flying off into oblivion.. but by golly, I'm gonna learn a few things from it all.

Rich

ps. maybe the old timers used one of these:
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