Ok - so here’s another hoopy idea…
Well, I’m still reflecting on the fact that playing a whistle is more like blowing across a demijohn than playing a trumpet, in that most of the air stays put rather than travels down the bore. I was thinking about how this affects making a whistle - I’ve had a go at making Guido’s plastic whistles and also at making a metal whistle with only limited success, largely due to my lack of practical skill. With the metal one, I could never get the airway just right, despite hours of hammering and lifting it back up.
So, here’s the hoopy idea…
To make sure that the air goes out through the window and not down the tube, why not block the tube off at the end, or maybe partially block it? Admittedly this changes the pitch of the bass note, but if your making one from a length of pipe, it’s just a case of gradually sawing it down to size anyhow.
I have just tried this with one of my failed attempts at a PVC whistle which has a wooden fipple and hey presto - it now whistles!
Has anyone else tried this?
Cheers,
Mike
In order to cause the vibration that results in a musical note, you need a flux
between air going out the window and air going down the tube. I wouldn’t
think a fully closed tube would do much for you…
“I wouldn’t think a fully closed tube would do much for you…”
Centuries of organ builders would argue that a closed tube works just fine!
-dan
Not if you by “fully closed” mean a solid body 
but then is more of a prop than a whistle 
Mike, Nelson McAvaoy (who contributes here on C&F from time to time) has the written down the fundamentals for you here:
http://www.flutephysics.com
It is well written and covers many aspects of flute acoustics that will aid the development of your whistle design.
For further resources I recommend the following two books:
The Physics of Musical Instruments (Fletcher, NH)
Acoustical Aspects of Woodwind Instruments (Nederveen, CJ)
Now, go study!
/MarcusR
The air shooting across has to be modulated by the vibrating air in the bore. Typically, wide windways do a better job at modulating as long as they’re made properly.
An closed ended pipe plays in a different octave and is strong in odd harmonics. Would sound like a train whistle or a calliope.
In an open ended pipe, the length from the window down to the open hole sets up a pressure charge/discharge cycle, the longer the distance the more amount of area that the air has to to fill up, which results in a lower note.
I made a three fipple whistle mouthpiece once, loud as heck but takes an incredible amount of air.
From the Kings Mills Institute of Tin Whistle Science 
If I understand your idea correctly, a closed end whistle would be basically an ocarina. You can only get one octave out of them.
No, the difference is that the lowest note of the closed pipe will be found at half the frequency compared to to open pipe, for a given length of the tube. The closed pipe will also lack the even harmonic serie and overblow at the twelfth instead of the octave.
Here is a nice illustration:
http://www.phys.unsw.edu.au/jw/flutes.v.clarinets.html
/MarcusR
Close, but not exactly. Ocarinas typically are classed by their wide bore or globular form. A closed ended cylinder behaves a little different. They will overblow but it gets weird on the upper octave, tuning shifts.
The closest thing to a bottom closed whistle would be a slide whistle.
I use close ended drones on the bagwhistle. They help conserve the air and are only half the size of open ended pipes at the same pitch.
Or a pan flute. Now, an instrument which played like a whistle but sounded like a pan flute would be worth having. But, if I’m not mistaken, uncovering a finger hole would basically change it into an open pipe again and ruin the effect…right?
An intriguing idea, anyway.
T
Have a look at these links…
http://www.mimf.com/link.htm#flutes
I recommend Kim Fulton Bennet’s tin whistle site and Pete Kosel’s Flutomat calculator. If you really want to know about flute acoustics, I suggest the craft manuals here…
http://www.shakuhachi.com/TOC-CM.html