Lt-40 no i was refering to the classic 40 size high wing trainer.

I recently bought the alpha trainer 40 and waiting to fly it. How long should a tank last at half throttle?
Also, I thought my wings might snap just doing a gentle roll, not necessarily true?

Tank should last at least 15 minutes and maybe as much as 20 depending on just how low you reduce the power.

If assembled properly the Alpha is quite strong. I've put them through aggressive loops, rolls and spins without any problems. Hardest manuever an any trainer wing is usually a high G pullout from a dive, usually done when saving the plane from student error.