Yes, Denny Rowland lost his on the maiden flight. I arrived at the site about ten minutes after the crash, so I don't really know the facts. He said he was turning upwind to land & it dropped a wing & went in. Others I spoke to thought he was going too slow & it stalled. They are not easy to stall, so he must have been flying really slow.

Duncan. I found I preferred the large Viper over the small version, especially the landings (although the small one is fine). I lost the small one when one of the main gears refused to come down. I climbed high & tried a couple of loops to free the jammed gear. Unfortunately on the second loop, it snapped & went into a flatish spiral dive. No matter what I tried, I had no effect on the spin.
Both Vipers were lost on the same day. Should have stayed at home that day.