You can reduce the amount of air needed for the Clarke original by carefully squishing the area above the fipple block. However, this can loosen the block as the sides of the mouthpiece move outward. Also, if you go too far, it may be tough to pry it back up without damaging it, so I’d advise waiting till you have another whistle available before trying it.
It helped mine quite a bit, but I still don’t like it well enough to play it now that I have a bunch of better whistles available.
I started with a Clark original. Was the first whistle I ever owned. But, I actually threw it in the trash. It did take more air than almost any I’ve tried since.
The whistle that requires the least amount that I know of is a Dixon with brass tuning slide.
I too have had problems with asthma and need all the help I can get. One tip that I can offer is not to eat before playing. Leaves more room for your lungs to expand. Works for me anyways.
I also had problems with a low D. It takes some concentration, but I’ve learned to really fill the lungs instead of just breathing in. Makes a big difference.
Hope this helped.
Mike
If you’re looking at lung use for musicians, Arnold Jacobs ( www.windsongpress.com ) was the guru. He was a tuba player, but he taught players of most woodwind instruments, as well as singers. In addition to having done a great deal of excellent research, he was a fantastic teacher. His research, writings, and even video of his masterclasses are available.