Single use composite engines have been difficult to find the last couple of years and when you do find them they are much more costly than they were in the past. This led me to rely more on CTI reloads for mid power flights. In addition, I started building and launching more rockets that use 24mm black powder engines. Most notably the Estes C11-5 which I could purchase from AC Supply for less than $5.00 for a two pack. All of a sudden these engines are not available. What's the deal with that? Why would Estes discontinue making such a popular all purpose engine? Even the C11-3 has seemed to disappear. The C11-7 seems to be available.
Years ago I built a 18 to 24mm adapter. It wasn't all that great but I used it a few times. Early this year I put in a rocket order for engines and other stuff and ordered the Estes 18 to 24mm adapter set. I think it came with three. It works well. A C6 does not have as much thrust as a C11 but in some cases it gets the job done.
Maybe we will have to start buying those new Quest engines.
I have to say it's a bit irritating when something I like gets the axe from a manufacturer of any kind. That said, I have a lot more warmth about Estes than I did a decade ago when they were run buy jerks. I'm not thrilled with the C11 discontinuation especially, but I'm really jazzed up about the new Saturn V, which in turn is tempered by the dwindling list of builders kits in the PS II line. I went and purchased another Sahara before they are all gone too.... shouldve gotten the Panavia when I had the chance...