How about a trike trainer on a string? This one is a wind powered trike, the string might not be included :-). Anyways, I want one too. I bet is a lot of fun and cheap to fly, as long as you don't have to pay the "string guy". Fly Safe!
I really like this video. Highlights the electric motor version (HPD 10 rated at 10 Kw => 13.5 hp). Very aerodynamically clean trike. Great battery life when shu...s of all rigid wings that could be flown on a light trike...