Another angle to the plug for flat-bottom wing trainers.

Tower Hobbies has a policy (think its still in effect) that if you buy one of their trainers they will replace it if you crash within 60 days of the purchase. I can attest to this because they replaced my 60-size trainer when I tip-stalled it one day taking off before it was ready to fly. Since I was pretty much done with trainers at the time I ended up selling that extra kit -- almost got all of my original investment back.