I don't know why I do it. I just do. It must be like the old tale of hitting one self on the head with a hammer. (It feels so good when you stop.) But I went to an ammonia balloon flight last weekend. Braack, Cough, Yetch. It is an experience that sticks with you.
I just wanted to test a couple of left over Bitterfeld "Pleiades Seven" balloon cells with ammonia to see how they would handle. The Beazlys were flying Ammonia from Adair, Illinois and invited me down. It is just a good days drive south and south is the right direction from Minnesota in February.
When we flew these same cells in Germany with hydrogen, and in Central Park with helium, you couldn't tell how much of those colorless odorless gases you were ingesting. But with ammonia you know! I wanted to see how my built in inflation/diffuser sleeve would work, whether or not the ammonia would go right to the top or spill out around the bottom. That was just fine, but when we had packed these bags up in New York, it was raining and now it was well below freezing in Adair.
Because the bags had developed a myriad of pin holes from the ice we couldn't get any lift measurements and so had to let the bottom tie offs go. That let the balloons lurch up to the end of the tether lines at the tops and turn turtle, letting out their ammonia high in the air. Again, no problem with ingesting the gas. But as the ammonia doesn't have the lift of hydrogen or helium it just didn't all get out. There was still considerable gas left to bite when it came time to pack the (almost completely) deflated bags away. And bite it did.
Stuffing a leaky balloon into a bag is great, if the stuff leaking out is old hot air or even helium. But just try it with ammonia and there is no place to hide. Like the smoke from a campfire it is perverse and always follows you as you try to dodge away. Talk about St. Vitus Dance! The conclusion is that while for ammonia ballooning the Pleiades system will work very well, it will have to be with disposable cells. And, believe me, I am disposing of those two. At least those two specific units will never come back to haunt as subjects of a product liability suit.
Since, with ammonia, they don't have to be metalized to protect against static electricity, just plain poly will do. That means much less cost of film and tape and much less labor to fabricate. Since ammonia has less lift, they can be bigger and have lower unit stress. That means they can be very light and inexpensive. Because there is such a multiple redundancy, extra thin poly can be used safely. If you are not going to try to save them for repeated use you don't care if they are destroyed on landing and deflation.
One great thing about this is that I have learned that the tightness in my chest and shortness of breath is not an imminent heart attack but simply the trauma of an ammonia attack on the eyes, nose and throat. I feel great. Put away the hammer, I'm going flying.