Just curious.
Anyone know who started making the curved windway/curved fipple style whistle (like a Sindt, Schultz or Burke)? Seems like a large percentage of the modern makers are using this technique now. The first I remember seeing was a Susanto.
Thanks
His name was Ug and he was a lot of fun around the campfire in the evenings.
Form follows function. A professor at a local university might say it is the product of Intelligent Design. Take a look at many of the cane/bamboo instruments available round the globe that have curved windways. If you take a round tube cut a groove and then insert a plug and wrap it with another tube you naturally get a curved windway. Drilling a bore whcih results in a round hole is mechanically easier than cutting/broaching a squared hole. It’s the easiest design to produce, in my opinion. I don’t think there is an inventor, per se. That’s my thinking anyway.
First instrument I ever made was back in the late '70s and was a bamboo whistle with a cork plug filed flat to create a semicircular windway. It was something I made as part of an “intercession” (between winter and spring quarters) in college, and I have fond memories, though it was a lousy instrument.
I’m more interested in the curved style of windway used in the whistles I mentioned earlier. Most of these appear to be made with a cylindrical inner plug, cut out slot in the whistle body to make the windway and blade, and a cylindrical outer mouthpiece that completes the windway section. This forms a windway that is curved on both the “top” and “bottom”, as opposed to the semicircular shape. From what I recall of your whistles, from a previous avatar, they also appear to be made this way. I think the final tube wrapping is the trickiest part of the construction, if using primitive methods, as the tolerances are more difficult to achieve than a filed rectangular slot and a flattened plug. Still, who knows, I’m just intrigued by the current proliferation of the design style as compared to the more rectangular crossection of windway used in Clarke, and Generation style whistles.
I recall from my reading of primative skills and artifacts that tight tolerances weren’t uncommon in anything that was a valuable product.
I was serious. 
The curved windway is the most natural way to make a windway in a tube. I believe it is of pre-historic origins. Regardless of whether the first curved windway was made in a section of bone, cane, bamboo or a hollowed-out twig, I believe it is the simplest and most obvious way to make a whistle head. Lathes, drill presses and milling machines have just made it easier to get the design specs we want.
Yes. I make whistles just as you describe. I’ve made whistles to many other designs too. And I’m always looking for new ones too. What I found was that allowing the shape of the materials to form the limits on the windway made a more consistent whistle. I think Ug could have come to a similar conclusion working in his man-cave. I think the KISS principle helps proliferate this design. Every piece is concentric. I don’t think it is as difficult to produce as a flat or a good semi-circular windway either(unless the exit of the windway is left round). But that probably depends on what tooling and methods you want to bring into play. I’ve made whistles and recorders using the traditional flat windway using either files or a broaching tool to form the duct and it is, in my experience at least, more time consuming to do than simply cutting a slot in a tube.
Part of what I see in the designs used by Susato, MK, Burke and Impempe, just as examples, is that their designs help control the variables leading to consistent voicing. That’s the big trick in making a good whistle over and over again. And each of those makers has a slightly different approach but all are simple and at the same time elegant. The Sindt and Weasel designs are more straightforward but do require great precision to get everything right, as you have said.
The original Clarke whistle is, in contrast to those above, a bit of an anachronism. It is 19th century tin bench-craft at its best. The Gen and others like them should gain consistency from the design of the mold but we’ve all seen unusual outcomes from that. Still, it’s generally a good product at a good price. Why they chose to use a flat windway is a mystery to me. Maybe they just think the world is flat. Maybe it’s that Flageolet ancestry at play. They made tin plate whistles with flat windways like the Clarke before they made the molded heads.
It’s an interesting question.
Feadoggie
Well, many Recorder makers (not all) used flat windway because they would use a flat broaching tool to make the windway. Typically their headjoints are very thick and a very different design than whistle headjoints.
For those making windways using broaching tools and flat files are limited by the shape of the tool.
Lots do use a curved windway. However, the windway is often not concentric with the bore, as it usually is in curved windway whistles. The windway of a recorder usually has a larger radius than the bore. I’m sure glad I don’t have to make them that way 
I can’t think offhand of any good quality machine or craftsman made recorders with flat windways. I could be wrong, but.
I think some companies (Hohner and Kung, or maybe Huber) did make flat windway recorders some time ago, but anything made as a replica of 17th and 18th century instruments (which means the vast majority of high quality recorders) will have a curved windway. As I understand it, the main payoff is that the instrument can be made more powerful because the curved labium has a longer edge than a flat one. Also, since the labium is set into a curve, it is less likely to distort over time due to repeated wetting/drying cycles, whereas a flat labium would be more prone to warping up or down.
I often hear on this forum that a curved windway is less likely to block with condensation, but I’m sceptical about that, I have to say. I have a Coolsma alto which is very tightly voiced, and if it isn’t warmed up well before playing, it tends to clog very easily. I think there’s much more involved than simply curved/not curved.
Interesting topic. Having matriculated from recorder to whistle, I can offer my experience. I’m not convinced at all the curved windways clog less than do flat. The design/height/material of the windway and the players ability seem to have more of an effect than the curvature. And curved recorders do generally have a larger radius than the bore. I own a Kung keyless tenor *(flat windway) which has such tremendous volume it will make the walls shake. I also have a Moeck keyless bubinga tenor (curved windway) which is at least 10db quieter than the Kung. Both are less than 5 years old and have about the same playable range two octaves and a sixth and both are well in tune. My Andrea Breuknik alto has a curved windway and my Fehr Model III has a flat windway. Neither clog, both have great volume and are in tune. I own both whistles and recorders that do clog if I’m not paying attention (I learned to “suck back” long ago to the point where it is as natural as taking a breath) but it is a mixed bag of flat and curved windways.
IMO, most high quality recorder makers offer curved windways as they are indeed more precise and durable. But my Goldie whistles are as flat as a pancake and I have no problem with them clogging (suck back!).
I do believe that Ug was the inventor though. I’ve seen “whistles” in museum’s going back hundreds of years with curved windway’s. Seems logical to me. He wasn’t much of a musician though. Like rock music too much. Get it, “rock” music.
ecohawk
He did have a very good drummer though! I think Atouk was his name.
Breaking News! Rare video footage of the invention of music shows the first whistle was made from a chicken bone!
Yes, that is Atouk’s band. He gets by with a little help from his friends!