RE: Ground effect on a Bipe
Run into a couple that had bad attitude on takeoffs. All of them required their own throttle on takeoff technique. Some could take 50% throttle applied quickly, some wouldn't take any quickness on the throttle no matter what percentage was given.
I've always thought that if they'll taxi with an degree of success, they'll take off if you just get the acceleration right.
We're all spoiled with the short takeoffs most models will do. Some of these suckers however just take some runway for them to behave.
I've got a Decathlon that's a beast if you push the throttle forward too fast. And it does great with gradual throttle advance. Watching a gradual throttle advance takeoff you'd never suspect that sucker was such a witch.